IRS1

Gene Summary

Gene:IRS1; insulin receptor substrate 1
Aliases: HIRS-1
Location:2q36
Summary:This gene encodes a protein which is phosphorylated by insulin receptor tyrosine kinase. Mutations in this gene are associated with type II diabetes and susceptibility to insulin resistance. [provided by RefSeq, Nov 2009]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:insulin receptor substrate 1
HPRD
Source:NCBIAccessed: 06 August, 2015

Ontology:

What does this gene/protein do?
Show (49)
Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 06 August 2015 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Breast Cancer
  • Phosphatidylinositol 3-Kinases
  • Transcriptome
  • Somatomedins
  • Insulin
  • Thiazolidinediones
  • Cell Proliferation
  • Case-Control Studies
  • Polymorphism
  • Mutation
  • MicroRNAs
  • Tumor Markers
  • Prostate Cancer
  • Neoplastic Cell Transformation
  • Colorectal Cancer
  • ras Proteins
  • Polycystic Ovary Syndrome
  • Messenger RNA
  • Insulin-Like Growth Factor I
  • RB1
  • AKT1
  • IRS1
  • Xenograft Models
  • Transfection
  • Genetic Predisposition
  • Structure-Activity Relationship
  • Insulin Receptor Substrate Proteins
  • Protein Transport
  • Sucrose
  • Proto-Oncogene Proteins
  • Receptor, Insulin
  • Insulin Resistance
  • Chromosome 2
  • Phosphorylation
  • IGF1R
  • Genetic Variation
  • Phosphoproteins
  • Up-Regulation
  • Genotype
  • Intracellular Signaling Peptides and Proteins
  • Cancer Gene Expression Regulation
Tag cloud generated 06 August, 2015 using data from PubMed, MeSH and CancerIndex

Specific Cancers (3)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: IRS1 (cancer-related)

Choi MR, Yoo NJ, An CH, Lee SH
Frameshift mutations in mammalian target of rapamycin pathway genes and their regional heterogeneity in sporadic colorectal cancers.
Hum Pathol. 2015; 46(5):753-60 [PubMed] Related Publications
Mammalian target of rapamycin (mTOR) pathway is known to be involved in cancer pathogenesis. The aim of our study was to find whether mTOR-related genes were mutated and expressionally altered in colorectal cancers (CRCs). Through public database searching, we found that PIK3CB, insulin receptor substrate 1/2 (IRS1), RPS6, EIF4B, RPS6KA5, and PRKAA2 that were known as mTOR-related genes possessed mononucleotide repeats in DNA coding sequences that could be mutated in cancers with microsatellite instability (MSI). We analyzed 124 CRCs by single-strand conformation polymorphism analysis and DNA sequencing and found 7 (8.9%), 8 (10.1%), and 3 (3.8%) of 79 CRCs with high MSI that harbored IRS1, EIF4B, and RPS6KA5 frameshift mutations, respectively. These mutations were not identified in stable MSI/low MSI (0/45). In addition, we analyzed intratumoral heterogeneity (ITH) of PIK3CB, IRS1, RPS6, EIF4B, RPS6KA5, and PRKAA2 frameshift mutations in 16 CRCs and found that IRS1, EIF4B, and RPS6KA5 mutations had regional ITH in 2, 2, and 1 CRCs, respectively. We also analyzed IRS1 expression in the CRCs by immunohistochemistry. Loss of IRS1 expression was identified in 31% of the CRCs. The loss of expression was more common in those with IRS1 mutation than those with wild-type IRS1. Our data indicate mTOR-related genes harbored not only somatic mutations but also mutational ITH and loss of expression, which together might play a role in tumorigenesis of CRC, especially with high MSI. Our data also suggest that mutation analysis in multiregional areas is needed for a precise evaluation of mutation status in CRC with MSI-H.

Su W, Xu M, Chen X, et al.
MiR200c targets IRS1 and suppresses prostate cancer cell growth.
Prostate. 2015; 75(8):855-62 [PubMed] Related Publications
BACKGROUND: The downregulation of the tumor suppressor miR200c plays important roles in many malignant tumors. This study aims to show that miR200c is a posttranscriptional regulator of insulin receptor substrate 1 (IRS1) and over-expression of miR200c suppresses prostate cancer cell growth.
METHODS: Bioinformatics analysis was used to show potential post-translational regulation of IRS1 by miR200c. Dual reporter gene assays were chosen to test the binding of miR200c to the potential seed sequences in IRS1 3'UTR. RT-PCR, Q-PCR and western blot were applied to determine the regulation effect of miR200c on IRS1. CCK8 assay, soft agar assay, trypan blue exclusion assay and flow cytometric analysis were used to measure the biological effects of miR200c on prostate cancer cell proliferation and apoptosis.
RESULTS: The 449-455 nt, 3061-3067 nt, and 3096-3102 nt of the IRS1 3'-UTR were identified as three potential seed sequences for miR200c. MiR200c directly binds to IRS1 through the seed sequences in IRS1 3'-UTR. Artificial overexpression of miR200c significantly downregulated the mRNA and protein levels of IRS1, together with decreased cell proliferation and increased cell death of PC3 and DU145 cells.
CONCLUSIONS: Our results suggest that miR200c plays crucial roles in prostate cancer by post-transcriptional regulation of IRS1. The mir200c/IRS1 pathway may be a potential therapeutic target to prevent prostate cancer cell growth.

Pekow J, Meckel K, Dougherty U, et al.
Tumor suppressors miR-143 and miR-145 and predicted target proteins API5, ERK5, K-RAS, and IRS-1 are differentially expressed in proximal and distal colon.
Am J Physiol Gastrointest Liver Physiol. 2015; 308(3):G179-87 [PubMed] Article available free on PMC after 01/02/2016 Related Publications
The colon differs regionally in local luminal environment, excretory function, and gene expression. Polycistronic microRNA (miR)-143 and miR-145 are downregulated early in colon cancer. We asked if these microRNAs (miRNAs) might be differentially expressed in the proximal vs. the distal colon, contributing to regional differences in protein expression. Primary transcripts and mature miR-143 and miR-145 were quantified by real-time PCR, putative targets were measured by Western blotting, and DNA methylation was assessed by sequencing bisulfite-treated DNA in proximal and distal normal colonic mucosa as well as colon cancers. Putative targets of these miRNAs were assessed following transfection with miR-143 or miR-145. Mean expression of mature miR-143 and miR-145 was 2.0-fold (P < 0.001) and 1.8-fold (P = 0.03) higher, respectively, in proximal than distal colon. DNA methylation or primary transcript expression of these miRNAs did not differ by location. In agreement with increased expression of miR-143 and miR-145 in proximal colon, predicted targets of these miRNAs, apoptosis inhibitor 5 (API5), ERK5, K-RAS, and insulin receptor substrate 1 (IRS-1), which are cell cycle and survival regulators, were expressed at a lower level in proximal than distal colon. Transfection of HCA-7 colon cancer cells with miR-145 downregulated IRS-1, and transfection of HT-29 colon cancer cells with miR-143 decreased K-RAS and ERK5 expression. In conclusion, miR-143 and miR-145 and the predicted target proteins API5, ERK5, K-RAS, and IRS-1 display regional differences in expression in the colon. We speculate that differences in these tumor suppressors might contribute to regional differences in normal colonic gene expression and modulate site-specific differences in malignant predisposition.

Luo J, Wen Q, Li J, et al.
Increased expression of IRS-1 is associated with lymph node metastasis in nasopharyngeal carcinoma.
Int J Clin Exp Pathol. 2014; 7(9):6117-24 [PubMed] Article available free on PMC after 01/02/2016 Related Publications
Nasopharyngeal carcinoma (NPC) is a head and neck malignant tumor rare throughout most of the world but common in Southeast Asia, especially in Southern China, which is with characteristics of early cervical lymph node metastasis and high incidence rate of distant metastasis. Insulin receptor substrate 1 (IRS-1) is a signaling adapter protein that is encoded by the IRS-1 gene in humans, plays an important role in the development, progression, invasion and metastasis of tumors. The aim of the present study was to investigate the association between the expression of IRS-1 protein and clinicopathological characteristics in NPC by immunohistochemistry. The results showed that the expression level of IRS-1 was significant higher in NPC than that in the control nasopharyngeal epithelia (P = 0.042). The positive percentage of IRS-1 expression in NPC with lymph node metastasis was also significantly higher than those without lymph node metastasis (P = 0.008). Positive expression of IRS-1 was proved to be the independent predicted factor for lymph node metastasis of NPC (P = 0.025) regardless of age, gender, histological type and clinical stages by multivariate logistic regression analysis. In addition, results showed higher sensitivity and agreement rate of IRS-1 for predicting lymph node metastasis of NPC patients. Taken together, high expression of IRS-1 might be closely correlated with lymph node metastasis in NPC and positive expression of IRS-1 could be used as an independent biomarker for predicting lymph node metastasis of NPC.

Lovly CM, McDonald NT, Chen H, et al.
Rationale for co-targeting IGF-1R and ALK in ALK fusion-positive lung cancer.
Nat Med. 2014; 20(9):1027-34 [PubMed] Article available free on PMC after 01/02/2016 Related Publications
Crizotinib, a selective tyrosine kinase inhibitor (TKI), shows marked activity in patients whose lung cancers harbor fusions in the gene encoding anaplastic lymphoma receptor tyrosine kinase (ALK), but its efficacy is limited by variable primary responses and acquired resistance. In work arising from the clinical observation of a patient with ALK fusion-positive lung cancer who had an exceptional response to an insulin-like growth factor 1 receptor (IGF-1R)-specific antibody, we define a therapeutic synergism between ALK and IGF-1R inhibitors. Similar to IGF-1R, ALK fusion proteins bind to the adaptor insulin receptor substrate 1 (IRS-1), and IRS-1 knockdown enhances the antitumor effects of ALK inhibitors. In models of ALK TKI resistance, the IGF-1R pathway is activated, and combined ALK and IGF-1R inhibition improves therapeutic efficacy. Consistent with this finding, the levels of IGF-1R and IRS-1 are increased in biopsy samples from patients progressing on crizotinib monotherapy. Collectively these data support a role for the IGF-1R-IRS-1 pathway in both ALK TKI-sensitive and ALK TKI-resistant states and provide a biological rationale for further clinical development of dual ALK and IGF-1R inhibitors.

Højlund K
Metabolism and insulin signaling in common metabolic disorders and inherited insulin resistance.
Dan Med J. 2014; 61(7):B4890 [PubMed] Related Publications
Type 2 diabetes, obesity and polycystic ovary syndrome (PCOS) are common metabolic disorders which are observed with increasing prevalences, and which are caused by a complex interplay between genetic and environmental factors, including increased calorie intake and physical inactivity. These metabolic disorders are all characterized by reduced plasma adiponectin and insulin resistance in peripheral tissues. Quantitatively skeletal muscle is the major site of insulin resistance. Both low plasma adiponectin and insulin resistance contribute to an increased risk of type 2 diabetes and cardiovascular disease. In several studies, we have investigated insulin action on glucose and lipid metabolism, and at the molecular level, insulin signaling to glucose transport and glycogen synthesis in skeletal muscle from healthy individuals and in obesity, PCOS and type 2 diabetes. Moreover, we have described a novel syndrome characterized by postprandial hyperinsulinemic hypoglycemia and insulin resistance. This syndrome is caused by a mutation in the tyrosine kinase domain of the insulin receptor gene (INSR). We have studied individuals with this mutation as a model of inherited insulin resistance. Type 2 diabetes, obesity and PCOS are characterized by pronounced defects in the insulin-stimulated glucose uptake, in particular glycogen synthesis and to a lesser extent glucose oxidation, and the ability of insulin to suppress lipid oxidation. In inherited insulin resistance, however, only insulin action on glucose uptake and glycogen synthesis is impaired. This suggests that the defects in glucose and lipid oxidation in the common metabolic disorders are secondary to other factors. In young women with PCOS, the degree of insulin resistance was similar to that seen in middle-aged patients with type 2 diabetes. This supports the hypothesis of an unique pathogenesis of insulin resistance in PCOS. Insulin in physiological concentrations stimulates glucose uptake in human skeletal muscle in vivo by activation of the insulin signaling cascade to glucose transport through the enzymes IRS1, PI3K, Akt2, AS160/TBC1D4 and RAC1, and to glycogen synthesis through Akt2, inhibition of GSK3 and activation of glycogen synthase (GS) via dephosphorylation of serine residues in both the NH2-terminal (site 2+2a) and the COOH-terminal end (site 3a+3b). In type 2 diabetes, obesity and PCOS, there is, although with some variation from study to study, defects in insulin signaling through IRS1, PI3K, Akt2 and AS160/TBC1D4, which can explain reduced insulin action on glucose transport. In type 2 diabetes an altered intracellular distribution of SNAP23 and impaired activation of RAC1 also seem to play a role for reduced insulin action on glucose transport. In all common metabolic disorders, we observed an impaired insulin activation of GS, which seems to be caused by attenuated dephosphorylation of GS at site 2+2a, whereas as the inhibition of GSK3 and the dephosphorylation of GS at its target sites, site 3a+3a, appeared to be completely normal. In individuals with inherited insulin resistance, we observed largely the same defects in insulin action on IRS1, PI3K, Akt2 and GS, as well as a normal inhibition of GSK3 and dephosphorylation of GS at site 3a+3b. In these individuals, however, a markedly reduced insulin clearance seems to partially rescue insulin signaling to glucose transport and GS. Adiponectin is thought to improve insulin sensitivity primarily by increasing lipid oxidation through activation of the enzyme AMPK, and possibly via cross-talking of adiponectin with insulin signaling, and hence glucose transport and glycogen synthesis. We demonstrated a strong correlation between plasma adiponectin and insulin action on glucose disposal and glycogen synthesis in obesity, type 2 diabetes and PCOS. In individuals with inherited insulin resistance, plasma adiponectin was normal, but the correlation of adiponectin with insulin-stimulated glucose uptake and glycogen synthesis was at least equally strong. Moreover, we found a correlation between plasma adiponectin and insulin activation of GS. This result is supported by a number of recent studies of animal models and muscle cell lines, which have shown that adiponectin augments insulin action on enzymes in the insulin signaling cascade. In contrast, we observed no differences in the abundance or activity of AMPK in obesity, type 2 diabetes, PCOS or inherited insulin resistance. This indicates that reduced insulin sensitivity in these conditions is not mediated via abnormal AMPK activity. The results from these studies demonstrate that the well-established abnormalities in insulin action on glucose uptake and glycogen synthesis are reflected by defects in insulin signaling to these cellular processes in type 2 diabetes, obesity, and PCOS, and as expected also in inherited insulin resistance caused by a mutation in INSR. In common metabolic disorders, low plasma adiponectin may contribute to insulin resistance and defects in insulin signaling, whereas in inherited insulin resistance a normal plasma adiponectin and reduced insulin clearance could contribute to maintain a sufficient activation of the insulin signaling cascade. The insight gained from these studies have improved our understanding of the molecular mechanisms underlying insulin resistance in skeletal muscle of humans, and can form the basis for further studies, which can lead to the development of treatment that more directly targets insulin resistance, and hence reduce the risk of type 2 diabetes and cardiovascular disease.

Pande M, Bondy ML, Do KA, et al.
Association between germline single nucleotide polymorphisms in the PI3K-AKT-mTOR pathway, obesity, and breast cancer disease-free survival.
Breast Cancer Res Treat. 2014; 147(2):381-7 [PubMed] Article available free on PMC after 01/09/2015 Related Publications
Obesity-related hormones and cytokines alter PI3 K-AKT-mTOR pathway activation in breast tumors contributing to poorer disease-free survival (DFS) and decreased responsiveness to tamoxifen and trastuzumab. We hypothesized that single nucleotide polymorphisms (SNPs) in candidate genes in the PI3 K-AKT-mTOR signaling pathway may act as genetic modifiers of breast cancer DFS. We analyzed the association of 106 tagging SNPs in 13 genes (ADIPOQ, IGF1, INS, IRS1, LEP, LEPR, LEPROT, PIK3CA, PIK3R5, PTEN, TSC1, TSC2, and AKT1) in the P13K-AKT-mTOR pathway with DFS in a sample of 1,019 women with stage I-II breast cancer. SNPs significantly associated with DFS in any genetic model (additive, dominant, or recessive) after correcting for false discovery rate (FDR = 0.10) were included in Cox proportional hazards multivariable analyses. After adjusting for race/ethnicity, age at diagnosis, tumor stage, and treatment, rs1063539 in ADIPOQ, rs11585329 in LEPR, and rs2519757 in TSC1 were associated with improved DFS, and rs1520220 in IGF1 and rs2677760 in PIK3CA were associated with worse DFS. The associations were not significantly modified by the type of systemic treatment received or body mass index. The SNPs were not associated with tumor characteristics such as tumor size, lymph node status, nuclear grade, or hormone receptor status. In this study, germline SNPs in the PI3 K-AKT-mTOR pathway were associated with breast cancer DFS and may be potential prognostic markers. Future studies are needed to replicate our results and to evaluate the relationship between these polymorphisms and activation of the PI3 K-AKT-mTOR pathway in breast tumors.

Chen L, Xu WM, Zhang D
Association of abdominal obesity, insulin resistance, and oxidative stress in adipose tissue in women with polycystic ovary syndrome.
Fertil Steril. 2014; 102(4):1167-1174.e4 [PubMed] Related Publications
OBJECTIVE: To study the expression of insulin signaling-related genes and oxidative stress markers in the visceral adipose tissue obtained from polycystic ovary syndrome (PCOS) patients and healthy control subjects and to investigate the relationships among abdominal obesity, insulin resistance, and oxidative stress at the tissue level.
DESIGN: Case-control study.
SETTING: University teaching hospital.
PATIENT(S): In total, 30 PCOS patients and 30 healthy control subjects, who underwent laparoscopic surgery, were included in the study.
INTERVENTION(S): Abdominal obesity was defined based on waist circumference (WC). The homeostasis model index was used to assess insulin resistance (HOMA-IR).
MAIN OUTCOME MEASURE(S): Gene expression of glucose transporter 4 (GLUT4) and insulin receptor substrate 1 (IRS1) in visceral adipose tissue (VAT) and the parameters of oxidative stress, such as superoxide dismutase, enzyme glutathione reductase, and dimethylarginine, were measured, and the expression of protein oxidative damage product 3-nitro-tyrosine residues (nitrotyrosine) in VAT was identified with the use of immunohistochemistry.
RESULT(S): PCOS was associated with lower expression of GLUT4 and IRS1 and a higher level of oxidative stress in VAT, which was strongly correlated with WC and HOMA-IR. Presence of abdominal obesity further intensified the correlations observed in our measurements. The nitrotyrosine expression in VAT was stronger in PCOS patients.
CONCLUSION(S): The strong correlation of insulin resistance with oxidative stress at the VAT level suggests that local oxidative stress and abnormalities of insulin signaling in adipose tissue play critical roles in the pathogenesis of PCOS.

Cao M, Li Y, Lu H, et al.
MiR-23a-mediated migration/invasion is rescued by its target, IRS-1, in non-small cell lung cancer cells.
J Cancer Res Clin Oncol. 2014; 140(10):1661-70 [PubMed] Related Publications
PURPOSE: To determine the interaction between insulin receptor substrate-1 (IRS-1) and miR-23a on the migration and invasion of non-small cell lung cancer (NSCLC) cells, and to examine IRS-1 expression in NSCLC tissues and its correlation with clinicopathologic characteristics.
METHODS: The migration and invasion of A549 cells were measured using transwell assay. miR-23a levels were examined by quantitative reverse transcription-PCR and IRS-1 expression by Western blotting. The interaction between miR-23a and IRS-1 was examined by luciferase reporter assay. IRS-1 expression in 105 NSCLC specimens was determined by immunohistochemistry and its correlation with patient clinicopathologic characteristics was evaluated.
RESULTS: Transwell assay revealed that miR-23a significantly promoted the migration and invasion of A549 cells with a 44.0 and 44.6 % increase in the number of migrated and invading cells, respectively. Luciferase assay showed that miR-23a markedly reduced luciferase activities of A549 cells co-transfected with plasmids overexpressing the 3' UTR of IRS-1 mRNA (P < 0.05). Co-transfection of A549 cells with miR-23a and plasmids overexpressing IRS-1 significantly reduced the increase in the number of migrated and invading cells mediated by miR-23a. Immunohistochemistry showed low IRS-1 expression in 26.7 % and high IRS-1 expression in 73.3 % of the NSCLC specimens. Kaplan-Meier analysis revealed that the overall survival and disease-free survival of NSCLC were markedly longer in patients with high IRS-1 expression than those with low IRS-1 expression (P = 0.002). Multivariate Cox regression analysis showed that IRS-1 was an independent prognostic factor for the overall survival of NSCLC patients (RR 0.413 CI 0.238-0.718, P = 0.002).
CONCLUSIONS: There is an interaction between miR-23a and IRS-1 in the modulation of the migration and invasion of NSCLC cells. IRS-1 is variably expressed in NSCLC patients and correlates with NSCLC patient survival.

Yang M, Shan X, Zhou X, et al.
miR-1271 regulates cisplatin resistance of human gastric cancer cell lines by targeting IGF1R, IRS1, mTOR, and BCL2.
Anticancer Agents Med Chem. 2014; 14(6):884-91 [PubMed] Related Publications
Numerous studies showed that drug resistance of gastric cancer cells could be modulated by the abnormal expression of microRNAs (miRNAs) which target multiple cell signaling pathways. The possible function of miR-1271 in the formation of cisplatin resistance in gastric cancer cells has been investigated in this study. miR-1271 was significantly down-regulated in gastric cancer tissues and various gastric cancer cell lines. Moreover, it was down-regulated in the cisplatin-resistant gastric cancer cell line SGC7901/cisplatin (DDP) and the down-regulation of miR-1271 in SGC7901/DPP cells was accompanied by the up-regulation of insulin-like growth factor 1 receptor (IGF1R)/insulin receptor substrate 1 (IRS1) pathway-related proteins, i.e., IGF1R, IRS1, serine/threonine-protein kinase mTOR (mTOR), and the apoptosis regulator Bcl-2 (BCL2), compared with the parental SGC7901 cells. Over-expression of miR-1271 sensitized SGC7901/DDP cells to cisplatin. Changes in the luciferase activity of reporter constructs harboring the 3'-untranslated region of the above proteins in SGC7901/DDP cells suggested that IGF1R, IRS1, mTOR, and BCL2 were target genes of miR-1271. Enforced miR-1271 expression repressed the protein levels of its targets, inhibited proliferation of SGC7901/DDP cells, and sensitized SGC7901/DDP cells to DDP-induced apoptosis. Overall, on the basis of the results of our study, we proposed that miR-1271 could regulate cisplatin resistance in human gastric cancer cells, at least partially, via targeting the IGF1R/IRS1 pathway.

Ujvari D, Hulchiy M, Calaby A, et al.
Lifestyle intervention up-regulates gene and protein levels of molecules involved in insulin signaling in the endometrium of overweight/obese women with polycystic ovary syndrome.
Hum Reprod. 2014; 29(7):1526-35 [PubMed] Related Publications
STUDY QUESTION: Does lifestyle intervention aiming at weight loss influence endometrial insulin signaling in overweight/obese women with polycystic ovary syndrome (PCOS)?
SUMMARY ANSWER: Lifestyle intervention up-regulates, both at the mRNA and protein levels, components of insulin signaling in the endometrium of overweight/obese PCOS women, in relation to an improved menstrual pattern.
WHAT IS KNOWN ALREADY: PCOS is a multifactorial endocrine disorder diagnosed by two of the following three criteria: chronic anovulation, hyperandrogenism and polycystic ovaries. Many women with PCOS also have insulin resistance and obesity. The syndrome is furthermore associated with endometrial cancer and possible alterations in endometrial function and receptivity.
STUDY DESIGN, SIZE, DURATION: This study assessed the effects of a combined diet and exercise lifestyle intervention for 3 months.
PARTICIPANTS/MATERIALS, SETTING, METHODS: A group of 20 overweight/obese PCOS women with anovulation, hyperandrogenism and polycystic ovaries were subjected to a combined diet and exercise program for 3 months. Ten body mass index (BMI)-matched regularly menstruating overweight/obese controls, nine normal-weight PCOS women and ten normal-weight controls were also included in the study. In an academic clinical setting, women were examined in mid-follicular phase for endocrine assessment and determination of endometrial levels of mRNA and immunohistochemical staining of insulin signaling molecules (the insulin receptor, insulin receptor substrate-1 (IRS1) and glucose transporter (GLUT) 1 and 4).
MAIN RESULTS AND THE ROLE OF CHANCE: Women with PCOS exhibited lower levels of IRS1 (P < 0.01) and GLUT4 (P < 0.01) mRNA in their proliferative endometrium than BMI-matched controls. After lifestyle intervention, weight loss averaged 4.7% and the menstrual pattern improved in 65% of the overweight/obese women with PCOS. Levels of IRS1 (P < 0.01) and GLUT1 (P < 0.05) mRNA were significantly up-regulated in the endometrium of those women with improved menstrual function, as were the protein expression levels of pY612IRS1 (the activated IRS1 form, P < 0.05), pS312IRS1 (the inhibitory form of IRS1, P < 0.05) and GLUT1 (P < 0.05). Improvement in the menstrual function of women in the obese/overweight group following the lifestyle intervention was positively correlated with the increase in the endometrial level of IRS1 mRNA (r = 0.63, P < 0.01) and negatively correlated with the change in BMI (r = -0.50, P < 0.05).
LIMITATIONS, REASONS FOR CAUTION: The number of women in each group was limited, although the power calculation indicated that the number of patients subjected to the lifestyle intervention was sufficient.
WIDER IMPLICATIONS OF THE FINDINGS: We propose that up-regulation of endometrial IRS1 and GLUT1 in overweight/obese women with PCOS following lifestyle intervention improves the glucose homeostasis and thereby restores the functioning of the endometrium in these women.
STUDY FUNDING/COMPETING INTEREST(S): This study was supported financially by the Swedish Research Council (A.L.H., 20324), Karolinska Institutet and the Stockholm County Council. None of the authors has any conflict of interest to declare.

Li P, Wang L, Liu L, et al.
Association between IRS-1 Gly972Arg polymorphism and colorectal cancer risk.
Tumour Biol. 2014; 35(7):6581-5 [PubMed] Related Publications
In order to make a comprehensive assessment of the potential association between one genetic variant in the insulin receptor substrate 1 (IRS-1) gene, rs1801278, and colorectal cancer (CRC) risk, we conducted a meta-analysis of four epidemiological studies, which included 3,708 CRC cases and 4,176 controls. The data showed that rs1801278 polymorphism was not associated with increased CRC risk in the overall population. When stratifying by the race, the results showed that the rs1801278 polymorphism was associated with increased CRC risk under dominant model in mixed populations. Based on this meta-analysis, we conclude that the IRS-1 rs1801278 polymorphism might be a risk factor for CRC development in mixed populations. Further studies, either with larger sample size or involving other single nucleotide polymorphisms (SNPs) and haplotypes of the IRS-1 gene, are necessary to clarify the contribution of IRS-1 rs1801278 in colorectal carcinogenesis.

Wang Y, Hu C, Cheng J, et al.
MicroRNA-145 suppresses hepatocellular carcinoma by targeting IRS1 and its downstream Akt signaling.
Biochem Biophys Res Commun. 2014; 446(4):1255-60 [PubMed] Related Publications
Accumulating evidences have proved that dysregulation of microRNAs (miRNAs) is involved in cancer initiation and progression. In this study, we showed that miRNA-145 level was significantly decreased in hepatocellular cancer (HCC) tissues and cell lines, and its low expression was inversely associated with the abundance of insulin receptor substrate 1 (IRS1), a key mediator in oncogenic insulin-like growth factor (IGF) signaling. We verified IRS1 as a direct target of miR-145 using Western blotting and luciferase reporter assay. Further, the restoration of miR-145 in HCC cell lines suppressed cancer cell growth, owing to down-regulated IRS1 expression and its downstream Akt/FOXO1 signaling. Our results demonstrated that miR-145 could inhibit HCC through targeting IRS1 and its downstream signaling, implicating the loss of miR-145 regulation may be a potential molecular mechanism causing aberrant oncogenic signaling in HCC.

Meerzaman DM, Yan C, Chen QR, et al.
Genome-wide transcriptional sequencing identifies novel mutations in metabolic genes in human hepatocellular carcinoma.
Cancer Genomics Proteomics. 2014 Jan-Feb; 11(1):1-12 [PubMed] Related Publications
We report on next-generation transcriptome sequencing results of three human hepatocellular carcinoma tumor/tumor-adjacent pairs. This analysis robustly examined ∼12,000 genes for both expression differences and molecular alterations. We observed 4,513 and 1,182 genes demonstrating 2-fold or greater increase or decrease in expression relative to their normal, respectively. Network analysis of expression data identified the Aurora B signaling, FOXM1 transcription factor network and Wnt signaling pathways pairs being altered in HCC. We validated as differential gene expression findings in a large data set containing of 434 liver normal/tumor sample pairs. In addition to known driver mutations in TP53 and CTNNB1, our mutation analysis identified non-synonymous mutations in genes implicated in metabolic diseases, i.e. diabetes and obesity: IRS1, HMGCS1, ATP8B1, PRMT6 and CLU, suggesting a common molecular etiology for HCC of alternative pathogenic origin.

Akker M, Güldiken S, Sipahi T, et al.
Investigation of insulin resistance gene polymorphisms in patients with differentiated thyroid cancer.
Mol Biol Rep. 2014; 41(5):3541-7 [PubMed] Related Publications
We aimed to investigate insulin receptor substrate-1 (IRS-1), insulin receptor substrate-2 (IRS-2), insulin-like growth factor binding protein-3 (IGFBP-3) genotypes, which are thought to be involved in the pathogenesis of many solid tumors and have thus far not been studied in patients with differentiated thyroid cancer (DTC). The study consisted of 93 patients diagnosed with DTC (79 females, 14 males) and 111 healthy control subjects (63 females, 48 males). The anthropometric measurements, lipid profiles, thyroid function tests and homeostatic model assessment (HOMA) as an indicator of insulin resistance (IR) of all patients were recorded. In addition IRS-1, IRS-2 and IGFBP-3 gene polymorphisms were determined by using polymerase chain reaction and restriction fragment length polymorphism. Hardy-Weinberg equilibrium was tested for each gene polymorphisms, and genetic effects were evaluated by the Chi Square test and multiple logistic regression. Homeostasis model assessment of insulin resistance (HOMA-IR), body mass index, waist circumference and serum total cholesterol levels were significantly higher in patients with DTC than in the control group. There was no difference between the two groups with respect to IRS-1, IRS-2 and IGFBP-3 gene polymorphisms. In addition, these gene polymorphisms were found to have no effect on lymph node metastases or tumor staging. While, obesity and increased HOMA-IR may be risk factors in DTC development, we suggest that IRS-1, IRS-2 and IGFBP-3 gene polymorphisms do not play an important role in pathogenesis of DTC.

Tomasetti M, Nocchi L, Staffolani S, et al.
MicroRNA-126 suppresses mesothelioma malignancy by targeting IRS1 and interfering with the mitochondrial function.
Antioxid Redox Signal. 2014; 21(15):2109-25 [PubMed] Article available free on PMC after 20/11/2015 Related Publications
AIMS: MiR126 was found to be frequently lost in many types of cancer, including malignant mesothelioma (MM), which represents one of the most challenging neoplastic diseases. In this study, we investigated the potential tumor suppressor function of MiR126 in MM cells. The effect of MiR126 was examined in response to oxidative stress, aberrant mitochondrial function induced by inhibition of complex I, mitochondrial DNA (mtDNA) depletion, and hypoxia.
RESULTS: MiR126 was up-regulated by oxidative stress in nonmalignant mesothelial (Met5A) and MM (H28) cell lines. In Met5A cells, rotenone inhibited MiR126 expression, but mtDNA depletion and hypoxia up-regulated MiR126. However, these various stimuli suppressed the levels of MiR126 in H28 cells. MiR126 affected mitochondrial energy metabolism, reduced mitochondrial respiration, and promoted glycolysis in H28 cells. This metabolic shift, associated with insulin receptor substrate-1 (IRS1)-modulated ATP-citrate lyase deregulation, resulted in higher ATP and citrate production. These changes were linked to the down-regulation of IRS1 by ectopic MiR126, reducing Akt signaling and inhibiting cytosolic sequestration of Forkhead box O1 (FoxO1), which promoted the expression of genes involved in gluconeogenesis and oxidative stress defense. These metabolic changes induced hypoxia-inducible factor-1α (HIF1α) stabilization. Consequently, MiR126 suppressed the malignancy of MM cells in vitro, a notion corroborated by the failure of H28(MiR126) cells to form tumors in nude mice.
INNOVATION AND CONCLUSION: MiR126 affects mitochondrial energy metabolism, resulting in MM tumor suppression. Since MM is a fatal neoplastic disease with a few therapeutic options, this finding is of potential translational importance.

Contaldo C, Myers TJ, Zucchini C, et al.
Expression levels of insulin receptor substrate-1 modulate the osteoblastic differentiation of mesenchymal stem cells and osteosarcoma cells.
Growth Factors. 2014; 32(1):41-52 [PubMed] Related Publications
The insulin-like growth factor-1 system, including its critical mediator insulin receptor substrate-1 (IRS-1), is involved in regulating osteosarcoma (OS) cell proliferation or differentiation. The aim of this study is to define the role of IRS-1 in OS cells by assessing the contribution of IRS-1 in the differentiation of human and murine OS cell lines and mouse mesenchymal stem cells (MSCs) and found that the basal level of IRS-1 is important for the initiation of differentiation. Both down-regulation and over-expression of IRS-1 inhibited osteoblastic differentiation. In vivo studies showed that OS cells over-expressing IRS-1 have increased metastatic potential and tumor growth. The proteasome inhibitor MG-132 led to an increase in IRS-1 protein level that inhibited osteoblastic differentiation, suggesting a role for proteasomal regulation in maintaining the appropriate expression level of IRS-1. Thus, precise regulation of IRS-1 expression level is critical for determining the differentiating capacity of MSCs and OS cells, and that derangement of IRS-1 levels can be a critical step in OS transformation.

Wei W, Jiang M, Luo L, et al.
Colorectal cancer susceptibility variants alter risk of breast cancer in a Chinese Han population.
Genet Mol Res. 2013; 12(4):6268-74 [PubMed] Related Publications
Recent genome wide association studies (GWAS) and candidate gene studies have revealed many novel loci associated with colorectal cancer susceptibility. We evaluated the effect of these colorectal cancer-associated variants on the risk of breast cancer in a Chinese Han population. Seven single nucleotide polymorphisms (SNPs) (rs3856806 in PPARG, rs7014346 in POU5F1P1, rs989902 in PTPN13, rs1801278 in IRS1, rs7003146 in TCF7L2, rs1503185 in PTPRJ, and rs63750447 in MLH1) were genotyped in Han Chinese subjects, including 216 patients with breast cancer and 216 matched controls, using the Sequenom MassARRAY platform. The association of genotypes with susceptibility to breast cancer was analyzed using the odds ratio (OR), with 95% confidence interval (CI) and logistic regression. Three SNPs (rs7014346, rs989902, and rs7003146) were found to be significantly associated with the susceptibility of breast cancer. The GA and AA genotypes of rs7003146 in TCF7L2, and the CA and CC genotype of rs989902 in PTPN13 were associated with reduced breast cancer risk in the Chinese Han population based on the best-fit dominant model. The GG genotype of rs7014346 in POU5F1P1 was also significantly associated with decreased breast cancer risk under the best-fit additive model. Our results confirmed the association of rs7014346 in POU5F1P1, rs989902 in PTPN13, and rs7003146 in TCF7L2 with variations in the risk of breast cancer in a Chinese Han population.

Parvaiz F, Manzoor S, Iqbal J, et al.
Hepatitis C virus nonstructural protein 5A favors upregulation of gluconeogenic and lipogenic gene expression leading towards insulin resistance: a metabolic syndrome.
Arch Virol. 2014; 159(5):1017-25 [PubMed] Related Publications
Chronic hepatitis C is a lethal blood-borne infection often associated with a number of pathologies such as insulin resistance and other metabolic abnormalities. Insulin is a key hormone that regulates the expression of metabolic pathways and favors homeostasis. In this study, we demonstrated the molecular mechanism of hepatitis C virus (HCV) nonstructural protein 5A (NS5A)-induced metabolic dysregulation. We showed that transient expression of HCV NS5A in human hepatoma cells increased lipid droplet formation through enhanced lipogenesis. We also showed increased transcriptional expression of peroxisome proliferator-activated receptor gamma coactivator (PGC)-1α and diacylglycerol acyltransferase-1 (DGAT-1) in NS5A-expressing cells. On the other hand, there was significantly reduced transcriptional expression of microsomal triglyceride transfer protein (MTP) and peroxisome proliferator-activated receptor γ (PPARγ) in cells expressing HCV NS5A. Furthermore, increased gluconeogenic gene expression was observed in HCV-NS5A-expressing cells. In addition, it was also shown that HCV-NS5A-expressing hepatoma cells show serine phosphorylation of IRS-1, thereby hampering metabolic activity and contributing to insulin resistance. Therefore, this study reveals that HCV NS5A is involved in enhanced gluconeogenic and lipogenic gene expression, which triggers metabolic abnormality and impairs insulin signaling pathway.

Hao Y, Zhao S, Wang Z
Targeting the protein-protein interaction between IRS1 and mutant p110α for cancer therapy.
Toxicol Pathol. 2014; 42(1):140-7 [PubMed] Article available free on PMC after 20/11/2015 Related Publications
Phosphoinositide-3-kinase, catalytic, alpha polypeptide, which encodes the catalytic p110α subunit of phosphatidylinositol 3-kinase α, is the most frequently mutated oncogene in human cancers. Targeting mutant p110α holds great promise for cancer therapy. However, it is challenging to develop p110α isoform-specific inhibitors. Most p110α mutations occur at two hot spot regions: an acidic cluster (E542, E545, and Q546) in the helical domain and a histidine residue (H1047) in the kinase domain. We recently discovered that p110α helical domain mutant proteins, but not the kinase domain mutant proteins, directly associate with insulin receptor substrate 1 (IRS1). Moreover, we demonstrated that disruption of protein-protein interaction between p110α helical domain mutant and IRS1 inhibits the growth of tumors with such mutations. The direct protein interaction between IRS1 and p110α helical domain mutants may provide a more accessible target for developing novel precision cancer therapy.

Noguchi A, Kikuchi K, Ohtsu T, et al.
Pulmonary tumors associated with the JC virus T-antigen in a transgenic mouse model.
Oncol Rep. 2013; 30(6):2603-8 [PubMed] Article available free on PMC after 20/11/2015 Related Publications
Many attempts to demonstrate the oncogenic role of the JC virus (JCV) have been partially successful in producing brain tumors, either by direct inoculation of JCV into the brain or in transgenic models in rodents. We previously reported the presence of JCV DNA with a relatively high incidence in pulmonary and digestive organs. However, we could not prove the oncogenic role of JCV. We prepared a transgene composed of the K19 promoter, specific to bronchial epithelium with the JCV T-antigen and established transgenic (TG) mice. Pulmonary tumors were detected without any metastasis in 2 out of 15 (13.3%) 16-month-old K19/JCV T-antigen TG mice. Using immunohistochemistry (IHC), these tumors showed JCV T-antigen, p53 and CK 19 expression, but not expression of nuclear and cytoplasmic β-catenin and insulin receptor substrate 1 (IRS1). IHC revealed the same expression pattern as in the bronchial epithelium of the TG mice. One tumor, which was examined with laser capture microdissection and molecular biological tools, demonstrated an EGFR mutation but not a K-ras mutation. We propose that the pulmonary tumors were derived from the JCV T-antigen in a TG mouse model. These findings shed light on pulmonary carcinogenesis.

Hoxhaj G, Dissanayake K, MacKintosh C
Effect of IRS4 levels on PI 3-kinase signalling.
PLoS One. 2013; 8(9):e73327 [PubMed] Article available free on PMC after 20/11/2015 Related Publications
Insulin receptor substrate 1 (IRS1) and IRS2 are well-characterized adapter proteins that relay signals from receptor tyrosine kinases to downstream components of signalling pathways. In contrast, the function of IRS4 is not well understood. IRS4 overexpression has been associated with acute lymphoblastic leukaemia and subungual exostosis, while point mutations of IRS4 have been found in melanomas. Here, we show that while IRS4 expression is low in most cancer cell lines, IRS4 mRNA and protein levels are markedly elevated in certain cells including the NCI-H720, DMS114, HEK293T and HEK293AAV lines. Surprisingly, IRS4 expression was also strongly induced when HEK293 cells were infected with retroviral particles and selected under puromycin, making IRS4 expression a potential off-target effect of retroviral expression vectors. Cells with high expression of IRS4 displayed high phosphatidylinositol (3,4,5)-trisphosphate (PIP3) levels, as well as elevated Akt and p70 S6 kinase activities, even in the absence of growth factors. PI 3-kinase (PI3K) signalling in these cells depends on IRS4, even though these cells also express IRS1/2. Knockdown of IRS4 also inhibited cell proliferation in cells with high levels of IRS4. Together, these findings suggest IRS4 as a potential therapeutic target for cancers with high expression of this protein.

Roszak J, Smok-Pieniążek A, Nocuń M, Stępnik M
Characterization of arsenic trioxide resistant clones derived from Jurkat leukemia T cell line: focus on PI3K/Akt signaling pathway.
Chem Biol Interact. 2013; 205(3):198-211 [PubMed] Related Publications
In this study the role of PI3K/Akt signaling pathway in arsenic trioxide (ATO)-treated parental Jurkat cells and also in derived ATO-resistant clones grown in the presence of given ATO concentration was investigated. ATO-resistant clones (cultured for 8-12weeks in the presence of 1, 2.5 and 5μM ATO) were characterized by high viability in the presence of ATO but slower growth rate compared to the parental cells. Morphological and functional characterization of derived ATO-resistant clones revealed that they did not differ fundamentally from parental Jurkat cells in terms of cell size, level of GSH, the lysosomal fluorescence or CD95/Fas surface antigen expression. However, a slight increase in the mitochondrial potential (JC-1 staining) was detected in the clones compared to parental Jurkat cells. Side population analysis (Vybrant DyeCycle Violet™ staining) in ATO resistant clones did not indicate any enrichment withcancer stem cells. Akt1/2, AktV or wortmannin inhibitors decreased viability of ATO-resistant clones grown in the presence of ATO, with no effect on ATO-treated parental cells. Flow cytometry analysis showed that ATO decreased the level of p-Akt in ATO-treated parental cells, while the resistant clones exhibited higher levels of p-Akt immunostaining than parental Jurkat cells. Expression analysis of 84 genes involved in the PI3K/Akt pathway revealed that this pathway was predominantly active in ATO-resistant clones. c-JUN seems to play a key role in the induction of cell death in ATO-treated parental Jurkat cells, as dose-dependent strong up-regulation of JUN was specific for the ATO-treated parental Jurkat cells. On the other hand, changes in expression of cyclin D1 (CCND1), insulin receptor substrate 1 (IRS1) and protein kinase C isoforms (PRKCZ,PRKCB and PRKCA) may be responsible for the induction of resistance to ATO. The changes in expression of growth factor receptor-bound protein 10 (GRB10) observed in ATO-resistant clones suggest a possibility of induction of different mechanisms in development of resistance to ATO depending on the drug concentration and thus involvement of different signaling mediators.

Esposito DL, Verginelli F, Toracchio S, et al.
Novel insulin receptor substrate 1 and 2 variants in breast and colorectal cancer.
Oncol Rep. 2013; 30(4):1553-60 [PubMed] Article available free on PMC after 20/11/2015 Related Publications
The insulin/insulin-like growth factor pathway is involved in breast and colorectal cancer (CRC) development. In the present study, we analyzed the coding region and short intron-exon borders of the insulin receptor substrate 1 and 2 (IRS‑1 and IRS‑2) genes in 12 cell lines derived from breast cancer (BC), 14 cell lines derived from CRC and 33 primary CRCs. The nucleotide variants identified in BC were 3 in IRS‑1, 1 of which (p.Arg267Cys) was novel and with a pathogenic potential as predicted by in silico analysis and 6 in IRS‑2. Twenty‑one variants in IRS‑1 and 18 in IRS‑2 were identified in the CRC samples. These included 11 novel IRS‑1 variants detected exclusively in CRCs, which included 5 missense (p.Pro559Leu, p.Gln655His, p.Asp1014Gly, p.Asp1181His and pPro1203Ser) with a pathogenic potential as predicted by in silico analysis, 2 frameshifts predicted to generate a truncated protein, 1 splice-site mutation and 3 silent variants. In the CRC samples we also identified 7 novel IRS‑2 variants, including 4 missense variants, which included 2 (p.Asp782Asn and p.Gly1230Ser) with a pathogenic potential as predicted by in silico analysis, 2 frame insertion mutations and 1 silent variant. Most of the novel IRS‑1 and IRS‑2 variants may be involved in the modulation of IRS-1 or IRS‑2 functions and could be relevant to breast and colorectal tumorigenesis.

Maekawa R, Sato S, Yamagata Y, et al.
Genome-wide DNA methylation analysis reveals a potential mechanism for the pathogenesis and development of uterine leiomyomas.
PLoS One. 2013; 8(6):e66632 [PubMed] Article available free on PMC after 20/11/2015 Related Publications
BACKGROUND: The pathogenesis of uterine leiomyomas, the most common benign tumor in women, remains unclear. Since acquired factors such as obesity, hypertension and early menarche place women at greater risk for uterine leiomyomas, uterine leiomyomas may be associated with epigenetic abnormalities that are caused by unfavorable environmental exposures.
PRINCIPAL FINDINGS: Profiles of genome-wide DNA methylation and mRNA expression were investigated in leiomyomas and in myometrium with and without leiomyomas. Profiles of DNA methylation and mRNA expression in the myometrium with and without leiomyomas were quite similar while those in leiomyomas were distinct. We identified 120 genes whose DNA methylation and mRNA expression patterns differed between leiomyomas and the adjacent myometrium. The biological relevance of the aberrantly methylated and expressed genes was cancer process, including IRS1 that is related to transformation, and collagen-related genes such as COL4A1, COL4A2 and COL6A3. We also detected 22 target genes of estrogen receptor (ER) alpha, including apoptosis-related genes, that have aberrant DNA methylation in the promoter, suggesting that the aberrant epigenetic regulation of ER alpha-target genes contributes to the aberrant response to estrogen.
CONCLUSIONS: Aberrant DNA methylation and its related transcriptional aberration were associated with cancer processes, which may represent a critical initial mechanism that triggers transformation of a single tumor stem cell that will eventually develop into a monoclonal leiomyoma tumor. The aberrant epigenetic regulation of ER alpha-target genes also may contribute to the aberrant response to estrogen, which is involved in the development of uterine leiomyomas after menarche.

Kang NH, Hwang KA, Lee HR, et al.
Resveratrol regulates the cell viability promoted by 17β-estradiol or bisphenol A via down-regulation of the cross-talk between estrogen receptor α and insulin growth factor-1 receptor in BG-1 ovarian cancer cells.
Food Chem Toxicol. 2013; 59:373-9 [PubMed] Related Publications
Endocrine disrupting chemicals (EDCs) and estrogens appear to promote development of estrogen-dependent cancers, including breast and ovarian carcinomas. In this study, we evaluated the cell viability effect of BPA on BG-1 human ovarian cancer cells, along with the growth inhibitory effect of resveratrol (trans-3,4,5-trihydroxystilbene; RES), a naturally occurring phytoestrogen. In addition, we investigated the underlying mechanism(s) of BPA and RES in regulating the interaction between estrogen receptor alpha (ERα) and insulin-like growth factor-1 receptor (IGF-1R) signals, a non- genomic pathway induced by 17β-estradiol (E2). BPA induced a significant increase in BG-1 cell growth and up-regulated mRNA levels of ERα and IGF-1R. In parallel with its mRNA level, the protein expression of ERα was induced, and phosphorylated insulin receptor substrate-1 (p-IRS-1), phosphorylated Akt1/2/3, and cyclin D1 were increased by BPA or E2. However, RES effectively reversed the BG-1 cell proliferation induced by E2 or BPA by inversely down-regulating the expressions of ERα, IGF-1R, p-IRS-1, and p-Akt1/2/3, and cyclin D1 at both transcriptional and translational levels. Taken together, these results suggest that RES is a novel candidate for prevention of tumor progression caused by EDCs, including BPA via effective inhibition of the cross-talk of ERα and IGF-1R signaling pathways.

Gyurkó DM, Veres DV, Módos D, et al.
Adaptation and learning of molecular networks as a description of cancer development at the systems-level: potential use in anti-cancer therapies.
Semin Cancer Biol. 2013; 23(4):262-9 [PubMed] Related Publications
There is a widening recognition that cancer cells are products of complex developmental processes. Carcinogenesis and metastasis formation are increasingly described as systems-level, network phenomena. Here we propose that malignant transformation is a two-phase process, where an initial increase of system plasticity is followed by a decrease of plasticity at late stages of carcinogenesis as a model of cellular learning. We describe the hallmarks of increased system plasticity of early, tumor initiating cells, such as increased noise, entropy, conformational and phenotypic plasticity, physical deformability, cell heterogeneity and network rearrangements. Finally, we argue that the large structural changes of molecular networks during cancer development necessitate a rather different targeting strategy in early and late phase of carcinogenesis. Plastic networks of early phase cancer development need a central hit, while rigid networks of late stage primary tumors or established metastases should be attacked by the network influence strategy, such as by edgetic, multi-target, or allo-network drugs. Cancer stem cells need special diagnosis and targeting, since their dormant and rapidly proliferating forms may have more rigid, or more plastic networks, respectively. The extremely high ability of cancer stem cells to change the rigidity/plasticity of their networks may be their key hallmark. The application of early stage-optimized anti-cancer drugs to late-stage patients may be a reason of many failures in anti-cancer therapies. Our hypotheses presented here underlie the need for patient-specific multi-target therapies applying the correct ratio of central hits and network influences - in an optimized sequence.

Xing AY, Wang B, Shi DB, et al.
Deregulated expression of miR-145 in manifold human cancer cells.
Exp Mol Pathol. 2013; 95(1):91-7 [PubMed] Related Publications
MicroRNAs play important roles in the processes of tumor initiation and progression. The expression level of miR-145 in gastric, liver, and cervical cancers has been rarely investigated. Whether miR-145 may function as a common tumor suppressor in the generation of tumor phenotype needs to be clarified. miR-145 expression was determined by RT-qPCR in various human cancer tissues including those of gastric, liver, colon, and cervical cancers. Cancer cell lines were transfected with miR-145 precursor, anti-miR-145 inhibitor, or negative control, and cells' proliferation, migration, and invasion activities were analyzed. The gene target of miR-145 was confirmed by luciferase assay and Western blot. The miR-145 expression level was lower by 37.68-, 2.64-, 2.69- and 2.39-fold in gastric, liver, colon, and cervical cancer tissues, respectively, compared to corresponding nontumorous controls. Moreover, miR-145 levels were significantly downregulated in various cancer cell lines. We further demonstrated that miR-145 could suppress anchorage-independent growth and cell motility in both the liver cancer cell line Hep-G2 and the gastric cancer cell line MKN-45, and inhibited cell proliferation in a cell type-specific manner. Insulin receptor substrate-1 (IRS1) was identified as a target gene of miR-145, by which miR-145 was able to suppress cell proliferation. miR-145 suppresses cell proliferation, anchorage-independent growth, cell motility, and may serve as a tumor suppressor.

Zhang H, Wang A, Ma H, Xu Y
Association between insulin receptor substrate 1 Gly972Arg polymorphism and cancer risk.
Tumour Biol. 2013; 34(5):2929-36 [PubMed] Related Publications
Epidemiological studies investigating the association between the insulin receptor substrate 1 (IRS1) gene Gly972Arg (rs1801278) polymorphism and various carcinomas risk reported conflicting results. Thus, a systemic review and meta-analysis of published studies were performed to assess the possible association. A comprehensive search was conducted to identify all eligible studies of IRS1 Gly972Arg polymorphism and cancer risk. Odds ratios (ORs) and 95 % confidence intervals (CIs) were used to assess the strength of the associations. A total of 16 independent studies, including 11,776 cases and 11,654 controls, were identified. When all studies were pooled, we found a significant association between IRS1 Gly972Arg polymorphism and increased cancer risk under dominant model (OR = 1.16, 95 %CI = 1.04-1.30, P = 0.007) and allelic model (OR = 1.16, 95 %CI = 1.02-1.30, P = 0.02). In subgroup analysis based on cancer type, increased cancer risk was found in ovarian cancer (dominant: OR = 1.55, 95 %CI = 1.17-2.05, P = 0.002; allelic: OR = 1.55, 95 %CI = 1.19-2.01, P = 0.001), breast cancer (allelic: OR = 1.12, 95 %CI = 1.00-1.26, P = 0.05), and other cancers (allelic: OR = 1.31, 95 %CI = 1.00-1.71, P = 0.05). When stratified by study types, significant associations were observed in both cohort studies (dominant: OR = 1.25, 95 %CI = 1.06-1.47, P = 0.007; allelic: OR = 1.25, 95 %CI = 1.07-1.46, P = 0.005) and case-control studies (dominant: OR = 1.15, 95 %CI = 1.01-1.31, P = 0.04). In the subgroup analyses by ethnicity, significantly increased cancer risk was suggested among both Caucasians (dominant: OR = 1.13, 95 %CI = 1.02-1.26, P = 0.02; allelic: OR = 1.13, 95 %CI = 1.03-1.25, P = 0.01) and mixed population (dominant: OR = 1.22, 95 %CI = 1.01-1.46, P = 0.04). Our investigations demonstrate that IRS1 Gly972Arg polymorphism was associated with an increased risk of cancer, and additional well-designed studies are warranted to validate these findings.

Skrgatić L, Baldani DP, Gersak K, et al.
Genetic polymorphisms of INS, INSR and IRS-1 genes are not associated with polycystic ovary syndrome in Croatian women.
Coll Antropol. 2013; 37(1):141-6 [PubMed] Related Publications
Obesity and insulin resistance is a common finding in patients with polycystic ovary syndrome (PCOS). Significant number of PCOS women experience insulin resistance that is irrespective of the degree of obesity suggesting possible genetic basis. Therefore, several polymorphisms of the genes encoding for the insulin (INS), insulin receptor (INSR) or insulin receptor substrates (IRS) involved in postreceptor signaling have been explored for their association with abnormal sensitivity to insulin in PCOS. The aim of the present study was to determine whether selected polymorphisms of INS, INSR and IRS-1 are associated with the development of PCOS as well as with increased insulin resistance in Croatian women with PCOS. The study enrolled 150 women with PCOS and 175 control women. The diagnosis of PCOS was based on Rotterdam consensus criteria. Each subject underwent an evaluation of body mass index (BMI), hirsutism, acne and menstrual cycle abnormalities as well as follicular stimulating hormone (FSH), luteinizing hormone (LH), total and free testosterone, androstendione, dehydroepiandrosterone sulphate (DHEAS), sex hormone binding globulin (SHBG), fasting glucose and fasting insulin. Insulin resistance (IR) was quantified using the homeostatic model assessment of IR (HOMA-IR). Molecular analyses for the genetic polymorphisms were preformed. There was a significant difference in clinical and biochemical characteristics of the studied groups except for BMI and fasting glucose levels. No significant differences were observed in the genotype and allele distribution of the VNTR INS, C/T INSR, Gly792Arg IRS-1 polymorphisms between cases and controls. Moreover, no association was found between VNTR INS, C/T INSR and Gly792Arg IRS-1 polymorphism and parameters of insulin resistance in PCOS patients. In conclusion, our data does not support an association between VNTR INS, C/T INSR and Gly792Arg IRS-1 polymorphism and susceptibility to PCOS or insulin resistance in Croatian women with PCOS.

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