Gene Summary

Gene:DLX4; distal-less homeobox 4
Aliases: BP1, DLX7, DLX8, DLX9, OFC15
Summary:Many vertebrate homeo box-containing genes have been identified on the basis of their sequence similarity with Drosophila developmental genes. Members of the Dlx gene family contain a homeobox that is related to that of Distal-less (Dll), a gene expressed in the head and limbs of the developing fruit fly. The Distal-less (Dlx) family of genes comprises at least 6 different members, DLX1-DLX6. The DLX proteins are postulated to play a role in forebrain and craniofacial development. Three transcript variants have been described for this gene, however, the full length nature of one variant has not been described. Studies of the two splice variants revealed that one encoded isoform functions as a repressor of the beta-globin gene while the other isoform lacks that function. [provided by RefSeq, Jul 2008]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:homeobox protein DLX-4
Source:NCBIAccessed: 11 March, 2017


What does this gene/protein do?
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Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 11 March 2017 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.

Tag cloud generated 11 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (6)

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: DLX4 (cancer-related)

Ohshima Y, Kaira K, Yamaguchi A, et al.
Efficacy of system l amino acid transporter 1 inhibition as a therapeutic target in esophageal squamous cell carcinoma.
Cancer Sci. 2016; 107(10):1499-1505 [PubMed] Free Access to Full Article Related Publications
System l amino acid transporter 1 (LAT1) is highly expressed in various types of human cancer, and contributes to cancer growth and survival. Recently, we have shown that LAT1 expression is closely related to the growth and aggressiveness of esophageal cancer, and is an independent marker of poor prognosis. However, it remains unclear whether LAT1 inhibition could suppress esophageal cancer growth. In this study, we investigated the tumor-suppressive effects of the inhibition of LAT1. Both LAT1 and CD98, which covalently associates to LAT1 on the membrane, were expressed in human esophageal cancer cell lines KYSE30 and KYSE150. Quantitative PCR analysis showed that the expression of LAT1 was much higher than other subtypes of LAT. A selective inhibitor of LAT, 2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid (BCH), suppressed cellular uptake of l-(14) C-leucine and cell proliferation in a dose-dependent manner. It also suppressed phosphorylation of mammalian target of rapamycin, 4E-BP1, and p70S6K protein, and induced cell cycle arrest at G1 phase. These results suggest that suppression of both mammalian target of rapamycin signaling and cell cycle progression is involved in BCH-induced growth inhibition. In tumor-bearing mice, daily treatment with BCH significantly delayed tumor growth and decreased glucose metabolism, indicating that LAT1 inhibition potentially suppresses esophageal cancer growth in vivo. Thus, our results suggest that LAT1 inhibition could be a promising molecular target for the esophageal cancer therapy.

Mei H, Wang Y, Fan J, Lin Z
Alternative splicing of S6K1 promotes non-small cell lung cancer survival.
Tumour Biol. 2016; 37(10):13369-13376 [PubMed] Related Publications
Ribosomal S6 kinase 1 (S6K1) that acts downstream of the mammalian target of rapamycin (mTOR) plays an important role in cell proliferation, protein translation, and cell survival. The gene RPS6KB1 encoding for S6K1 had been found to be alternatively spliced to form different isoforms. In this study, we identified that short isoforms of S6K1 splice variant were overproduced in non-small cell lung cancer (NSCLC). Moreover, suppression of S6K1 short isoforms inhibited NSCLC cell growth and induced apoptosis via upregulation of the BH3-only protein Bim in vitro and in vivo. Additionally, short isoforms of S6K1 activated mTORC1, leading to increased 4E-BP1 phosphorylation. Taken together, our findings suggested that S6K1 short isoforms were deregulated in NSCLC and promoted cell survival. Altogether, our study opens possibilities of new therapeutic approaches for NSCLC that selectively downregulate S6K1 shorter isoforms.

Riquelme I, Tapia O, Espinoza JA, et al.
The Gene Expression Status of the PI3K/AKT/mTOR Pathway in Gastric Cancer Tissues and Cell Lines.
Pathol Oncol Res. 2016; 22(4):797-805 [PubMed] Related Publications
The PI3K/AKT/mTOR pathway plays a crucial role in the regulation of multiple cellular functions including cell growth, proliferation, metabolism and angiogenesis. Emerging evidence has shown that deregulation of this pathway has a role promoting gastric cancer (GC). The aim was to assess the expression of genes involved in this pathway by qPCR in 23 tumor and 23 non-tumor gastric mucosa samples from advanced GC patients, and in AGS, MKN28 and MKN45 gastric cancer cell lines. Results showed a slight overexpression of PIK3CA, PIK3CB, AKT1, MTOR, RPS6KB1, EIF4EBP1 and EIF4E genes, and a slightly decreased PTEN and TSC1 expression. In AGS, MKN28 and MKN45 cells a significant gene overexpression of PIK3CA, PIK3CB, AKT1, MTOR, RPS6KB1 and EIF4E, and a significant repression of PTEN gene expression were observed. Immunoblotting showed that PI3K-β, AKT, p-AKT, PTEN, mTOR, p-mTOR, P70S6K1, p-P70S6K1, 4E-BP1, p-4E-BP1, eIF4E and p-eIF4E proteins were present in cell lines at different levels, confirming activation of this pathway in vitro. This is the first time this extensive panel of 9 genes within PI3K/AKT/mTOR pathway has been studied in GC to clarify the biological role of this pathway in GC and develop new strategies for this malignancy.

Hayashi T, Kumasaka T, Mitani K, et al.
Bronchial involvement in advanced stage lymphangioleiomyomatosis: histopathologic and molecular analyses.
Hum Pathol. 2016; 50:34-42 [PubMed] Related Publications
Lymphangioleiomyomatosis (LAM), a rare progressive disease that almost exclusively affects women, is characterized by pulmonary cysts and neoplastic proliferation of smooth muscle-like cells (LAM cells). Airflow obstruction is a physiologic consequence that is commonly observed in LAM and has been attributed to narrowing of peripheral airways. However, histopathologic examinations of the entire airway have been precluded by the limited availability of such specimens. Here, we used explanted lung tissues from 30 LAM patients for a thorough histologic analysis with a special emphasis on the bronchi. We found bronchial involvement by LAM cells and lymphatics in all patients examined. Furthermore, a moderate to severe degree of chronic inflammation (73%), goblet cell hyperplasia (97%), squamous cell metaplasia (83%) of the epithelium, and thickening of basal lamina (93%) were identified in the bronchi. Because LAM cells are transformed by the functional loss of the TSC genes leading to a hyperactivated mammalian target of rapamycin complex 1 (mTORC1) signaling pathway, we confirmed the expression of phospho-p70S6K, phospho-S6, phospho-4E-BP1, and vascular endothelial growth factor (VEGF)-D in LAM cells from all of the patients examined. In contrast, no protein expression of hypoxia-inducible factor 1α, a downstream molecule indicative of mTORC1 activation and leading to VEGF production, was detected in any patient. Our study indicates that late-stage LAM patients commonly have bronchi involved by the proliferation of both LAM cells and lymphatics and that chronic inflammation complicated their disease. Furthermore, the up-regulation of hypoxia-inducible factor 1α, a common event in mTORC1-driven tumor cells, does not occur in LAM cells and plays no role in VEGF-D expression in LAM cells.

Ochnik AM, Peterson MS, Avdulov SV, et al.
Amplified in Breast Cancer Regulates Transcription and Translation in Breast Cancer Cells.
Neoplasia. 2016; 18(2):100-10 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Control of mRNA translation is fundamentally altered in cancer. Insulin-like growth factor-I (IGF-I) signaling regulates key translation mediators to modulate protein synthesis (e.g. eIF4E, 4E-BP1, mTOR, and S6K1). Importantly the Amplified in Breast Cancer (AIB1) oncogene regulates transcription and is also a downstream mediator of IGF-I signaling.
MATERIALS AND METHODS: To determine if AIB1 also affects mRNA translation, we conducted gain and loss of AIB1 function experiments in estrogen receptor alpha (ERα)(+) (MCF-7L) and ERα(-) (MDA-MB-231, MDA-MB-435 and LCC6) breast cancer cells.
RESULTS: AIB1 positively regulated IGF-I-induced mRNA translation in both ERα(+) and ERα(-) cells. Formation of the eIF4E-4E-BP1 translational complex was altered in the AIB1 ERα(+) and ERα(-) knockdown cells, leading to a reduction in the eIF4E/4E-BP1 and eIF4G/4E-BP1 ratios. In basal and IGF-I stimulated MCF-7 and LCC6 cells, knockdown of AIB1 decreased the integrity of the cap-binding complex, reduced global IGF-I stimulated polyribosomal mRNA recruitment with a concomitant decrease in ten of the thirteen genes tested in polysome-bound mRNAs mapping to proliferation, cell cycle, survival, transcription, translation and ribosome biogenesis ontologies. Specifically, knockdown of AIB1 decreased ribosome-bound mRNA and steady-state protein levels of the transcription factors ERα and E2F1 in addition to reduced ribosome-bound mRNA of the ribosome biogenesis factor BYSL in a cell-line specific manner to regulate mRNA translation.
CONCLUSION: The oncogenic transcription factor AIB1 has a novel role in the regulation of polyribosome recruitment and formation of the translational complex. Combinatorial therapies targeting IGF signaling and mRNA translation in AIB1 expressing breast cancers may have clinical benefit and warrants further investigation.

Qin X, Jiang B, Zhang Y
4E-BP1, a multifactor regulated multifunctional protein.
Cell Cycle. 2016; 15(6):781-6 [PubMed] Free Access to Full Article Related Publications
Eukaryotic translation initiation factor 4E (eIF4E)-binding protein 1 (4E-BP1) is a member of a family of translation repressor proteins, and a well-known substrate of mechanistic target of rapamycin (mTOR) signaling pathway. Phosphorylation of 4E-BP1 causes its release from eIF4E to allow cap-dependent translation to proceed. Recently, 4E-BP1 was shown to be phosphorylated by other kinases besides mTOR, and overexpression of 4E-BP1 was found in different human carcinomas. In this review, we summarize the novel findings on mTOR independent 4E-BP1 phosphorylation in carcinomas. The implications of overexpression and possible multi-function of 4E-BP1 are also discussed.

Liu F, Zhang W, Yang F, et al.
Interleukin-6-stimulated progranulin expression contributes to the malignancy of hepatocellular carcinoma cells by activating mTOR signaling.
Sci Rep. 2016; 6:21260 [PubMed] Free Access to Full Article Related Publications
This study aimed to determine the expression of progranulin (PGRN) in hepatocellular carcinoma (HCC) cells in response to interleukin 6 (IL-6), a non-cellular component of the tumor microenvironment, and the molecular mechanism of PGRN oncogenic activity in hepatocarcinogenesis. Levels of IL-6 and PGRN were increased and positively correlated in HCC tissues. IL-6 dose- and time-dependently increased PGRN level in HCC cells. IL-6-driven PGRN expression was at least in part mediated by Erk/C/EBPβ signaling, and reduced expression of PGRN impaired IL-6-stimulated proliferation, migration and invasion of HepG2 cells. PGRN activated mammalian target of rapamycin (mTOR) signaling, as evidenced by increased phosphorylation of p70S6K, 4E-BP1, and Akt-Ser473/FoxO1. Inhibition of mTOR signaling with rapamycin, an mTOR signaling inhibitor, disturbed PGRN- or IL-6-mediated proliferation, migration and invasion of HCC cells in vitro. Persistent activation of mTOR signaling by knockdown of TSC2 restored PGRN-knockdown-attenuated pro-proliferation effects of IL-6 in HepG2 cells. In addition, rapamycin treatment in vivo in mice slowed tumor growth stimulated by recombinant human PGRN. Our findings provide a better understanding of the biological activities of the IL-6/PGRN/mTOR cascade in the carcinogenesis of HCC, which may suggest a novel target in the treatment of HCC.

Demark-Wahnefried W, Nix JW, Hunter GR, et al.
Feasibility outcomes of a presurgical randomized controlled trial exploring the impact of caloric restriction and increased physical activity versus a wait-list control on tumor characteristics and circulating biomarkers in men electing prostatectomy for prostate cancer.
BMC Cancer. 2016; 16:61 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Obesity is associated with tumor aggressiveness and disease-specific mortality for more than 15 defined malignancies, including prostate cancer. Preclinical studies suggest that weight loss from caloric restriction and increased physical activity may suppress hormonal, energy-sensing, and inflammatory factors that drive neoplastic progression; however, exact mechanisms are yet to be determined, and experiments in humans are limited.
METHODS: We conducted a randomized controlled trial among 40 overweight or obese, newly-diagnosed prostate cancer patients who elected prostatectomy to explore feasibility of a presurgical weight loss intervention that promoted a weight loss of roughly one kg. week(-1) via caloric restriction and physical activity, as well as to assess effects on tumor biology and circulating biomarkers. Measures of feasibility (accrual, retention, adherence, and safety) were primary endpoints. Exploratory aims were directed at the intervention's effect on tumor proliferation (Ki-67) and other tumor markers (activated caspase-3, insulin and androgen receptors, VEGF, TNFβ, NFκB, and 4E-BP1), circulating biomarkers (PSA, insulin, glucose, VEGF, TNFβ, leptin, SHBG, and testosterone), lymphocytic gene expression of corresponding factors and cellular bioenergetics in neutrophils, and effects on the gut microbiome. Consenting patients were randomized in a 1:1 ratio to either: 1) weight loss via a healthful, guidelines-based diet and exercise regimen; or 2) a wait-list control. While biological testing is currently ongoing, this paper details our methods and feasibility outcomes.
RESULTS: The accrual target was met after screening 101 cases (enrollment rate: 39.6%). Other outcomes included a retention rate of 85%, excellent adherence (95%), and no serious reported adverse events. No significant differences by age, race, or weight status were noted between enrollees vs. non-enrollees. The most common reasons for non-participation were "too busy" (30%), medical exclusions (21%), and "distance" (16%).
CONCLUSIONS: Presurgical trials offer a means to study the impact of diet and exercise interventions directly on tumor tissue, and other host factors that are feasible and safe, though modifications are needed to conduct trials within an abbreviated period of time and via distance medicine-based approaches. Pre-surgical trials are critical to elucidate the impact of lifestyle interventions on specific mechanisms that mediate carcinogenesis and which can be used subsequently as therapeutic targets.

Llanos S, García-Pedrero JM, Morgado-Palacin L, et al.
Stabilization of p21 by mTORC1/4E-BP1 predicts clinical outcome of head and neck cancers.
Nat Commun. 2016; 7:10438 [PubMed] Free Access to Full Article Related Publications
The levels, regulation and prognostic value of p21 in head and neck squamous cell carcinomas (HNSCC) has been puzzling for years. Here, we report a new mechanism of regulation of p21 by the mTORC1/4E-BP1 pathway. We find that non-phosphorylated 4E-BP1 interacts with p21 and induces its degradation. Accordingly, hyper-activation of mTORC1 results in phosphorylation of 4E-BP1 and stabilization of p21. In HNSCC, p21 levels strongly correlate with mTORC1 activity but not with p53 status. Finally, clinical data indicate that HNSCC patients with p21 and phospho-S6-double-positive tumours present a better disease-specific survival. We conclude that over-activation of the mTORC1/4E-BP1/p21 pathway is a frequent and clinically relevant alteration in HNSCC.

Wang T, Seah S, Loh X, et al.
Simvastatin-induced breast cancer cell death and deactivation of PI3K/Akt and MAPK/ERK signalling are reversed by metabolic products of the mevalonate pathway.
Oncotarget. 2016; 7(3):2532-44 [PubMed] Free Access to Full Article Related Publications
Statins purportedly exert anti-tumoral effects on breast cancer. However, the biologic mechanisms for these actions are not fully elucidated. The aims of this study were 1) to explore the effects of simvastatin on apoptosis, proliferation as well as PI3K/Akt/mTOR and MAPK/ERK pathway in a window-of-opportunity breast cancer trial; 2) to further confirm findings from the clinical trial by functional studies; 3) to explore the regulatory role of mevalonate pathway on the anti-tumoral effects of simvastatin. In clinical samples, simvastatin led to increase in cleaved caspase-3 (p = 0.002) and decreased trend for Ki67 (p = 0.245). Simvastatin markedly suppressed PI3K/Akt/mTOR signalling by activating PTEN (p = 0.005) and by dephosphorylating Akt (p = 0.002) and S6RP (p = 0.033); it also inhibited MAPK/ERK pathway by dephosphorylating c-Raf (p = 0.018) and ERK1/2 (p = 0.002). In ER-positive (MCF-7, T47D) and ER-negative (MDA-MB-231, BT-549) breast cancer cells, simvastatin treatment consistently induced apoptosis and inhibited proliferation by deregulating caspase cascades and cell cycle proteins in a dose dependent manner. Concordantly, simvastatin strongly suppressed PI3K/Akt/mTOR pathway by enhancing PTEN expression and by further sequentially dephosphorylating downstream cascades including Akt, mTOR, p70S6K, S6RP and 4E-BP1. Furthermore, simvastatin significantly inhibited MAPK/ERK pathway by dephosphorylating sequential cascades such as c-Raf, MEK1/2 and ERK1/2. These simvastatin anti-tumoral effects were reversed by metabolic products of the mevalonate pathway, including mevalonate, farnesyl pyrophosphate and geranylgeranyl pyrophosphate. These findings shed light on the biological and potential anti-tumoral effects of simvastatin in breast cancer.

Langa BC, Oliveira MM, Pereira SR, et al.
Copy Number Analysis of the DLX4 and ERBB2 Genes in South African Breast Cancer Patients.
Cytogenet Genome Res. 2015; 146(3):195-203 [PubMed] Related Publications
Breast cancer is one of the main causes of cancer death among South African women. Although several risk factors can be attributed to the observed high mortality rate, the biology of the tumors is not extensively investigated. Copy number gain of the DLX4 homeobox gene has been observed in breast cancer in association with poor prognosis and specific racial groups. Therefore, we aimed to assess the copy number and prognostic role of DLX4 in breast cancer from South African patients. Due to the co-location of ERBB2 and DLX4 in the 17q21 region, its copy number was also evaluated. Our results in the analysis of 66 cases demonstrated copy number gains of DLX4 and ERBB2 in 24.1 and 29.7% of the cases, respectively. Linear regression analysis showed no dependency between the copy number alterations in these genes. Although not significant, patients with DLX4 and ERBB2 gains presented a higher frequency of advanced-grade tumors. In addition, copy number alterations of these genes were not significantly differently observed in the 3 main racial groups of the Western Cape population: Colored, White, and Black. These findings indicate that gains of DLX4 and ERBB2 occur in South African breast cancer patients irrespectively of their race and factors known to influence prognosis.

Ilmer M, Garnier A, Vykoukal J, et al.
Targeting the Neurokinin-1 Receptor Compromises Canonical Wnt Signaling in Hepatoblastoma.
Mol Cancer Ther. 2015; 14(12):2712-21 [PubMed] Related Publications
The substance P (SP)/NK-1 receptor (NK1R) complex represents an intriguing anticancer target for a variety of tumors, including hepatoblastoma (HB). Therefore, NK1R antagonists, such as the clinical drug aprepitant, recently have been proposed as potent anticancer agents. However, very little is known regarding the molecular basis of NK1R inhibition in cancer. Using reverse phase protein array, Western blot, Super TOP/FOP, confocal microscopy, and sphere formation ability (SFA) assays, we identified the AKT and Wnt signaling pathways as the key targets of aprepitant in three human HB cell lines (HepT1, HepG2, and HuH6). Following NK1R blockage, we observed decreased phosphorylation of p70S6K and 4E-BP1/2 and inhibition of the canonical Wnt pathway with subsequent decrease of HB cell growth. This effect was dependent of high baseline Wnt activity either by mutational status of β-catenin or extrinsic Wnt activation. Wnt inhibition seemed to be strengthened by disruption of the FOXM1-β-catenin complex. Furthermore, treatment of HB cells with aprepitant led to reduced expression of (liver) stemness markers (AFP, CD13, SOX2, NANOG, and OCT4) and SFA when grown under cancer stem cell conditions. Taken together, we show for the first time that targeting the SP/NK1R signaling cascade inhibits canonical Wnt signaling in HB cells. These findings reveal important insight into the molecular mechanisms of the SP/NK1R complex as a critical component in a model of pediatric liver cancer and may support the development of novel therapeutic interventions for HB and other Wnt-activated cancers.

Li H, Kong X, Cui G, et al.
Rapamycin restores p14, p15 and p57 expression and inhibits the mTOR/p70S6K pathway in acute lymphoblastic leukemia cells.
Int J Hematol. 2015; 102(5):558-68 [PubMed] Related Publications
The aim of the present study was to investigate the effects of rapamycin and its underlying mechanisms on acute lymphoblastic leukemia (ALL) cells. We found that the p14, p15, and p57 genes were not expressed in ALL cell lines (Molt-4 and Nalm-6) and adult ALL patients, whereas mTOR, 4E-BP1, and p70S6K were highly expressed. In Molt-4 and Nalm-6 cells exposed to rapamycin, cell viability decreased and the cell cycle was arrested at the G1/S phase. Rapamycin restored p14, p15, and p57 gene expression through demethylation of the promoters of these genes. As expected, rapamycin also increased p14 and p15 protein expression in both Molt-4 and Nalm-6 cells, as well as p57 protein expression in Nalm-6 cells. Rapamycin additionally decreased mTOR and p70S6K mRNA levels, as well as p70S6K and p-p70S6K protein levels. However, depletion of mTOR by siRNA did not alter the expression and promoter methylation states of p14, p15, and p57. These results indicate that the inhibitory effect of rapamycin may be due mainly to increased p14, p15, and p57 expression via promoter demethylation and decreased mTOR and p70S6K expression in ALL cell lines. These results suggest a potential role for rapamycin in the treatment of adult ALL.

Lv T, Wang Q, Cromie M, et al.
Twist1-mediated 4E-BP1 regulation through mTOR in non-small cell lung cancer.
Oncotarget. 2015; 6(32):33006-18 [PubMed] Free Access to Full Article Related Publications
Twist1 overexpression corresponds with poor survival in non-small cell lung cancer (NSCLC), but the underlining mechanism is not clear. The objective of the present study was to investigate the tumorigenic role of Twist1 and its related molecular mechanisms in NSCLC. Twist1 was overexpressed in 34.7% of NSCLC patients. The survival rate was significantly lower in patients with high Twist1 expression than low expression (P < 0.05). Twist1 expression levels were higher in H1650 cells, but relatively lower in H1975 cells. H1650 with stable Twist1 knockdown, H1650shTw, demonstrated a significantly slower rate of wound closure; however, H1975 with stable Twist1 overexpression, H1975Over, had an increased motility velocity. A significant decrease in colony number and size was observed in H1650shTw, but a significant increase in colony number was found in H1975Over (P < 0.05). Tumor growth significantly decreased in mice implanted with H1650shTw compared to H1650 (P < 0.05). 4E-BP1 and p53 gene expressions were increased, but p-4E-BP1 and p-mTOR protein expressions were decreased in H1650shTw. However, 4E-BP1 gene expression was decreased, while p-4E-BP1 and p-mTOR protein expressions were increased in H1975Over. p-4E-BP1 was overexpressed in 24.0% of NSCLC patients. Survival rate was significantly lower in patients with high p-4E-BP1 expression than low p-4E-BP1 (P < 0.01). A significant correlation was found between Twist1 and p-4E-BP1 (P < 0.01). A total of 13 genes in RT-PCR array showed significant changes in H1650shTw. Altogether, Twist1 is correlated with p-4E-BP1 in predicting the prognostic outcome of NSCLC. Inhibition of Twist1 decreases p-4E-BP1 expression possibly through downregulating p-mTOR and increasing p53 expression in NSCLC.

Zhou JD, Yang J, Guo H, et al.
BP1 overexpression is associated with adverse prognosis in de novo acute myeloid leukemia.
Leuk Lymphoma. 2016; 57(4):828-34 [PubMed] Related Publications
To investigate DLX4 isoforms expression and their clinical significance in acute myeloid leukemia (AML). DLX4 transcript variant 1 (BP1) expression was significantly up-regulated in AML patients compared with normal controls. However, DLX4 transcript variant 2 (DLX7) was significantly down-regulated in AML patients. Both in the overall AML and the non-M3 AML cohorts, those patients with high BP1 expression (BP1(high)) showed significantly lower rates of complete remission than those with low BP1 expression (BP1(low)). BP1(high) cases had significantly shorter overall survival than BP1(low) cases in the overall AML cohort, non-M3 AML, and cytogenetically normal AML (CN-AML). Multivariate analysis confirmed the independent prognostic value of BP1 expression among both the overall AML cohort and non-M3 AML as well as CN-AML patients. However, we did not observe the impact of DLX7 expression on prognosis in AML patients. Our study reveals that BP1 overexpression serves as an independent risk factor in de novo AML patients.

Wang H, Zhang Y, Lu Y, et al.
The role of stearoyl-coenzyme A desaturase 1 in clear cell renal cell carcinoma.
Tumour Biol. 2016; 37(1):479-89 [PubMed] Related Publications
This study aimed to investigate the correlations of stearoyl-coenzyme A desaturase 1 (SCD-1) with clear cell renal cell carcinoma (ccRCC) severity and PI3K-AKT-mTOR signaling pathway. From 2004 to 2006, tumor tissue and normal pericarcinomatous tissue from ccRCC samples were collected from ccRCC patients at Renji Hospital of Shanghai Jiaotong University. The expression of SCD-1 in the collected ccRCC samples and four cell lines (A498, 769-P, 786-O, and CAKI) was detected by Western blot. The correlation between SCD-1 expression and ccRCC severity was also analyzed by immunohistochemistry. Stable 786-O and 769-P ccRCC cells expressing SCD-1 short hairpin RNA (shRNA) were constructed, and the expression of proteins in the PI3K-AKT-mTOR signaling pathway was also detected. Finally, the inhibitory effect of PI3K-AKT-mTOR inhibitors (PI103, MK2206, rapamycin, AZD8055, and RAD001) on ccRCC cells stably expressing SCD-1 shRNA was also measured. Higher SCD-1 expression level was observed in ccRCC tissues compared with normal tissues. SCD-1 expression level was the highest in 786-O. SCD-1 expression was positively correlated with the tumor-node-metastasis (TNM) stage, grade of tumor cells, and lymphatic metastasis. There were no changes in the expression of AKT, ERK, PI3K, and PDK1. Significant differences were observed in the expression of p-AKT (at the Ser473 and Thr308 site), p-ERK, and two mTOR downstream molecules (4E-BP1 and p-P70S6K1) in cells stably expressing SCD-1 shRNA. PI103 and AZD8055 could enhance the inhibitory effect of SCD-1 interference on proliferation and migration of 786-O and 769-P cells. AZD8055 is recommended for the combined ccRCC treatment with shRNA interference.

Zhi X, Chen W, Xue F, et al.
OSI-027 inhibits pancreatic ductal adenocarcinoma cell proliferation and enhances the therapeutic effect of gemcitabine both in vitro and in vivo.
Oncotarget. 2015; 6(28):26230-41 [PubMed] Free Access to Full Article Related Publications
Despite its relative rarity, pancreatic ductal adenocarcinoma (PDAC) accounts for a large percentage of cancer deaths. In this study, we investigated the in vitro efficacy of OSI-027, a selective inhibitor of mammalian target of rapamycin complex 1 (mTORC1) and mTORC2, to treat PDAC cell lines alone, and in combination with gemcitabine (GEM). Similarly, we tested the efficacy of these two compounds in a xenograft mouse model of PDAC. OSI-027 significantly arrested cell cycle in G0/G1 phase, inhibited the proliferation of Panc-1, BxPC-3, and CFPAC-1 cells, and downregulated mTORC1, mTORC2, phospho-Akt, phospho-p70S6K, phospho-4E-BP1, cyclin D1, and cyclin-dependent kinase 4 (CDK4) in these cells. Moreover, OSI-027 also downregulated multidrug resistance (MDR)-1, which has been implicated in chemotherapy resistance in PDAC cells and enhanced apoptosis induced by GEM in the three PDAC cell lines. When combined, OSI-027 with GEM showed synergistic cytotoxic effects both in vitro and in vivo. This is the first evidence of the efficacy of OSI-027 in PDAC and may provide the groundwork for a new clinical PDAC therapy.

Karthik GM, Ma R, Lövrot J, et al.
mTOR inhibitors counteract tamoxifen-induced activation of breast cancer stem cells.
Cancer Lett. 2015; 367(1):76-87 [PubMed] Related Publications
Breast cancer cells with stem cell characteristics (CSC) are a distinct cell population with phenotypic similarities to mammary stem cells. CSCs are important drivers of tumorigenesis and the metastatic process. Tamoxifen is the most widely used hormonal therapy for estrogen receptor (ER) positive cancers. In our study, tamoxifen was effective in reducing proliferation of ER + adherent cancer cells, but not their CSC population. We isolated, expanded and incubated CSC from seven breast cancers with or without tamoxifen. By genome-wide transcriptional analysis we identified tamoxifen-induced transcriptional pathways associated with ribosomal biogenesis and mRNA translation, both regulated by the mTOR-pathway. We observed induction of the key mTOR downstream targets S6K1, S6RP and 4E-BP1 in-patient derived CSCs by tamoxifen on protein level. Using the mTOR inhibitors rapamycin, everolimus and PF-04691502 (a dual PI3K/mTOR inhibitor) and in combination with tamoxifen, significant reduction in mammosphere formation was observed. Hence, we suggest that the CSC population play a significant role during endocrine resistance through activity of the mTOR pathway. In addition, tamoxifen further stimulates the mTOR-pathway but can be antagonized using mTOR-inhibitors.

Chao MW, Wang LT, Lai CY, et al.
eIF4E binding protein 1 expression is associated with clinical survival outcomes in colorectal cancer.
Oncotarget. 2015; 6(27):24092-104 [PubMed] Free Access to Full Article Related Publications
eIF4E binding protein 1 (4E-BP1), is critical for cap-dependent and cap-independent translation. This study is the first to demonstrate that 4E-BP1 expression correlates with colorectal cancer (CRC) progression. Compared to its expression in normal colon epithelial cells, 4E-BP1 was upregulated in CRC cell lines and was detected in patient tumor tissues. Furthermore, high 4E-BP1 expression was statistically associated with poor prognosis. Hypoxia has been considered as an obstacle for cancer therapeutics. Our previous data showed that YXM110, a cryptopleurine derivative, exhibited anticancer activity via 4E-BP1 depletion. Here, we investigated whether YXM110 could inhibit protein synthesis under hypoxia. 4E-BP1 expression was notably decreased by YXM110 under hypoxic conditions, implying that cap-independent translation could be suppressed by YXM110. Moreover, YXM110 repressed hypoxia-inducible factor 1α (HIF-1α) expression, which resulted in decreased downstream vascular endothelial growth factor (VEGF) expression. These observations highlight 4E-BP1 as a useful biomarker and therapeutic target, indicating that YXM110 could be a potent CRC therapeutic drug.

Huang HG, Luo X, Wu S, Jian B
MiR-99a Inhibits Cell Proliferation and Tumorigenesis through Targeting mTOR in Human Anaplastic Thyroid Cancer.
Asian Pac J Cancer Prev. 2015; 16(12):4937-44 [PubMed] Related Publications
MicroRNAs (miRNAs) are emerging as critical regulators in carcinogenesis and tumor progression. Recently, miR-99a has been reported as a tumor suppressor gene in various human cancers, but its functions in the context of anaplastic thyroid cancer (ATC) remain unknown. In this study, we reported that miR-99a was commonly downregulated in ATC tissue specimens and cell lines with important functional consequences. Overexpression of miR-99a not only dramatically reduced ATC cell viability by inducing cell apoptosis and accumulation of cells at G1 phase, but also inhibited tumorigenicity in vivo. We then screened and identified a novel miR-99a target, mammalian target of rapamycin (mTOR), and it was further confirmed by luciferase assay. Up-regulation of miR-99a would markedly reduce the expression of mTOR and its downstream phosphorylated proteins (p-4E- BP1 and p-S6K1). Similar to restoring miR-99a expression, mTOR down-regulation suppressed cell viability and increased cell apoptosis, whereas restoration of mTOR expression significantly reversed the miR-99a antitumor activity and the inhibition of mTOR/p-4E-BP1/p-S6K1 signal pathway profile. In clinical specimens and cell lines, mTOR was commonly overexpressed and its protein levels were statistically inversely correlated with miR-99a expression. Taken together, our results demonstrated for the first time that miR-99a functions as a tumor suppressor and plays an important role in inhibiting the tumorigenesis through targeting the mTOR/p- 4E-BP1/p-S6K1 pathway in ATC cells. Given these, miR-99a may serve as a novel prognostic/diagnostic and therapeutic target for treating ATC.

Durbas M, Horwacik I, Boratyn E, et al.
GD2 ganglioside specific antibody treatment downregulates PI3K/Akt/mTOR signaling network in human neuroblastoma cell lines.
Int J Oncol. 2015; 47(3):1143-59 [PubMed] Related Publications
Mechanisms leading to inhibitory effects of an anti-GD2 ganglioside (GD2) 14G2a mouse monoclonal antibody (mAb) and PI3K/Akt/mTOR pathway inhibitors on human neuroblastoma cell survival were studied in vitro. We have recently shown on IMR-32, CHP‑134, and LA-N-1 neuroblastoma cells that targeting GD2 with the mAb decreases cell viability of the cell lines. In this study we used cytotoxicity assays, proteomic arrays and immunoblotting to evaluate the response of the three cell lines to the anti‑GD2 14G2a mAb and specific PI3K/Akt/mTOR pathway inhibitors. We show here that the mAb modulates intracellular signal transduction through changes in several kinases and their substrates phosphorylation. More detailed analysis of the PI3K/Akt/mTOR pathway showed significant decrease in activity of Akt, mTOR, p70 S6 and 4E-BP1 proteins and transient increase in PTEN (a suppressor of the pathway), leading to inhibition of the signaling network responsible for stimulation of translation and proliferation. Additionally, combining the GD2-specific 14G2a mAb with an Akt inhibitor (perifosine), dual mTOR/PI3K inhibitors (BEZ-235 and SAR245409), and a pan-PI3K inhibitor (LY294002) was shown to enhance cytotoxic effects against IMR-32, CHP‑134 and LA-N-1 cells. Our study extends knowledge on mechanisms of action of the 14G2a mAb on the neuroblastoma cells. Also, it stresses the need for further delineation of molecular signal orchestration aimed at more reasonable selection of drugs to target key cellular pathways in quest for better cure for neuroblastoma patients.

Zhou JD, Wang YX, Zhang TJ, et al.
Epigenetic inactivation of DLX4 is associated with disease progression in chronic myeloid leukemia.
Biochem Biophys Res Commun. 2015; 463(4):1250-6 [PubMed] Related Publications
Aberrant DNA methylation of various genes has been identified to be associated with disease progression in chronic myeloid leukemia (CML). Our study was intended to investigate DLX4 methylation pattern in different clinical stages of CML and further determine its role in regulating DLX4 expression. Real-time quantitative methylation-specific PCR and bisulfite sequencing PCR were applied to detect DLX4 methylation. 5-aza-2'-deoxycytidine (5-aza-dC) was used for demethylation studies. DLX4 was significantly hypermethylated in CML patients (P = 0.002) especially in blastic phase (BC) stage (P < 0.001) as compared with controls. Moreover, DLX4 methylation level in BC stage was significantly higher than in chronic phase (CP) stage (P < 0.001). DLX4 methylation density was significantly increased during the progression of CML among the tested two patients (P < 0.001). DLX4 hypermethylation occurred with the highest incidence in BC stage (83%), lower incidence in acute phase (AP) stage (43%), and the lowest incidence in CP stage (26%) (P = 0.001). Moreover, t(9; 22) with additional alteration cases had significantly higher frequency of DLX4 hypermethylation compared with the other cytogenetics (P = 0.010). Significantly negative correlation was observed between DLX4 methylation and DLX4-TV2 (the shorter DLX4 isoform) expression (R = -0.382, P = 0.001, n = 78) but not between DLX4 methylation and BP1 (the longer DLX4 isoform) expression (R = 0.134, P = 0.244, n = 78) in CML patients. Both DLX4-TV2 and BP1 mRNA were significantly increased after 5-aza-dC treatment in K562 cell line (P < 0.001). Our study indicated that hypermethylation of DLX4 correlated with disease progression of CML. Moreover, DLX4 expression was regulated by its methylation in CML.

Chou YS, Yang MH
Epithelial-mesenchymal transition-related factors in solid tumor and hematological malignancy.
J Chin Med Assoc. 2015; 78(8):438-45 [PubMed] Related Publications
The epithelial-mesenchymal transition (EMT) process plays pivotal roles in regulatory mechanisms of embryogenesis and wound healing physiologically, and organ fibrosis, cancer progression, and metastasis pathologically. EMT is classified as primary, secondary, and tertiary during embryonic development. EMT contributes to repair of tissue injury and fibrogenesis by re-epithelialization and regeneration of fibroblasts, respectively. The hallmarks of EMT include loss of contact inhibition, remodeling of extracellular matrix, and reorganization of cytoskeleton, along with expression of mesenchymal markers and reduction of epithelial markers. Cancer cells acquire stemness, migration and invasive capability, evade apoptosis, and initiate metastasis to distant organs. Several EMT regulators including Snail, Zeb1, Zeb2, and Twist in solid tumor and Sox4, distal-less homeobox gene 4 (DLX4), Prdm14, Bmi1, and the forkhead box family in hematological malignancy are reviewed with regard to their signaling pathways, regulatory mechanisms, and clinical interactions.

Haria D, Trinh BQ, Ko SY, et al.
The homeoprotein DLX4 stimulates NF-κB activation and CD44-mediated tumor-mesothelial cell interactions in ovarian cancer.
Am J Pathol. 2015; 185(8):2298-308 [PubMed] Free Access to Full Article Related Publications
Ovarian cancers often highly express inflammatory cytokines and form implants throughout the peritoneal cavity. However, the mechanisms that drive inflammatory signaling and peritoneal metastasis of ovarian cancer are poorly understood. We previously identified that high expression of DLX4, a transcription factor encoded by a homeobox gene, is associated with reduced survival of ovarian cancer patients. In this study, we identified that DLX4 stimulates attachment of ovarian tumor cells to peritoneal mesothelial cells in vitro and increases the numbers of peritoneal implants in xenograft models. DLX4 induced expression of the cell surface molecule CD44 in ovarian tumor cells, and inhibition of CD44 abrogated the ability of DLX4 to stimulate tumor-mesothelial cell interactions. The induction of CD44 by DLX4 was attributed to increased activity of NF-κB that was stimulated by the inflammatory cytokine IL-1β, a transcriptional target of DLX4. The stimulatory effects of DLX4 on CD44 levels and tumor-mesothelial cell interactions were abrogated when IL-1β or NF-κB was inhibited in tumor cells. Furthermore, DLX4 expression levels strongly correlated with NF-κB activation and disease stage in clinical specimens of ovarian cancer. Collectively, these findings indicate that DLX4 induces CD44 by stimulating IL-1β-mediated NF-κB activity, thereby promoting peritoneal metastasis of ovarian cancer.

Chen BW, Chen W, Liang H, et al.
Inhibition of mTORC2 Induces Cell-Cycle Arrest and Enhances the Cytotoxicity of Doxorubicin by Suppressing MDR1 Expression in HCC Cells.
Mol Cancer Ther. 2015; 14(8):1805-15 [PubMed] Free Access to Full Article Related Publications
mTOR is aberrantly activated in hepatocellular carcinoma (HCC) and plays pivotal roles in tumorigenesis and chemoresistance. Rapamycin has been reported to exert antitumor activity in HCC and sensitizes HCC cells to cytotoxic agents. However, due to feedback activation of AKT after mTOR complex 1 (mTORC1) inhibition, simultaneous targeting of mTORC1/2 may be more effective. In this study, we examined the interaction between the dual mTORC1/2 inhibitor OSI-027 and doxorubicin in vitro and in vivo. OSI-027 was found to reduce phosphorylation of both mTORC1 and mTORC2 substrates, including 4E-BP1, p70S6K, and AKT (Ser473), and inhibit HCC cell proliferation. Similar to OSI-027 treatment, knockdown of mTORC2 induced G0-G1 phase cell-cycle arrest. In contrast, rapamycin or knockdown of mTORC1 increased phosphorylation of AKT (Ser473), yet had little antiproliferative effect. Notably, OSI-027 synergized with doxorubicin for the antiproliferative efficacy in a manner dependent of MDR1 expression in HCC cells. The synergistic antitumor effect of OSI-027 and doxorubicin was also observed in a HCC xenograft mouse model. Moreover, AKT was required for OSI-027-induced cell-cycle arrest and downregulation of MDR1. Our findings provide a rationale for dual mTORC1/mTORC2 inhibitors, such as OSI-027, as monotherapy or in combination with cytotoxic agents to treat HCC. Mol Cancer Ther; 14(8); 1805-15. ©2015 AACR.

Yu L, Shang ZF, Wang J, et al.
PC-1/PrLZ confers resistance to rapamycin in prostate cancer cells through increased 4E-BP1 stability.
Oncotarget. 2015; 6(24):20356-69 [PubMed] Free Access to Full Article Related Publications
An important strategy for improving advanced PCa treatment is targeted therapies combined with chemotherapy. PC-1, a prostate Leucine Zipper gene (PrLZ), is specifically expressed in prostate tissue as an androgen-induced gene and is up-regulated in advanced PCa. Recent work confirmed that PC-1 expression promotes PCa growth and androgen-independent progression. However, how this occurs and whether this can be used as a biomarker is uncertain. Here, we report that PC-1 overexpression confers PCa cells resistance to rapamycin treatment by antagonizing rapamycin-induced cytostasis and autophagy (rapamycin-sensitivity was observed in PC-1-deficient (shPC-1) C4-2 cells). Analysis of the mTOR pathway in PCa cells with PC-1 overexpressed and depressed revealed that eukaryotic initiation factor 4E-binding protein 1(4E-BP1) was highly regulated by PC-1. Immunohistochemistry assays indicated that 4E-BP1 up-regulation correlates with increased PC-1 expression in human prostate tumors and in PCa cells. Furthermore, PC-1 interacts directly with 4E-BP1 and stabilizes 4E-BP1 protein via inhibition of its ubiquitination and proteasomal degradation. Thus, PC-1 is a novel regulator of 4E-BP1 and our work suggests a potential mechanism through which PC-1 enhances PCa cell survival and malignant progression and increases chemoresistance. Thus, the PC-1-4E-BP1 interaction may represent a therapeutic target for treating advanced PCa.

Wang Y, Zhi Q, Ye Q, et al.
SCYL1-BP1 affects cell cycle arrest in human hepatocellular carcinoma cells via Cyclin F and RRM2.
Anticancer Agents Med Chem. 2016; 16(4):440-6 [PubMed] Related Publications
The cell cycle is regulated via important biological mechanisms. Controlled expression of cell cycle regulatory proteins is crucial to maintain cell cycle progression. However, unbalanced protein expression leads to many diseases, such as cancer. Previous research suggests that SCYL1-BP1 function might be related to cell cycle progression and SCYL1-BP1 dysfunction to diseases through undefined mechanisms. In this research, an unbiased yeast two-hybrid screen was used to find protein(s) with potential biological relevance to SCYL1-BP1 function, and a novel interaction was recognized between SCYL1-BP1 and Cyclin F. This interaction was chosen as a paradigm to study SCYL1-BP1 function in cell cycle progression and its possible role in tumorigenesis. We found that SCYL1-BP1 binds to Cyclin F both in vivo and in vitro. SCYL1-BP1 overexpression promoted expression of the CCNF gene and simultaneously delayed Cyclin F protein degradation. SCYL1-BP1 knockdown reduced the expression of endogenous Cyclin F. It was also demonstrated in functional assays that SCYL1-BP1 overexpression induces G2/M arrest in cultured liver cells. Furthermore, SCYL1-BP1 sustained RRM2 protein expression by reducing its ubiquitination. Thus, we propose that SCYL1- BP1 affects the cell cycle through increasing steady state levels of Cyclin F and RRM2 proteins, thus constituting a dual regulatory circuit. This study provides a possible mechanism for SCYL1-BP1-mediated cell cycle regulation and related diseases.

Bommer UA, Iadevaia V, Chen J, et al.
Growth-factor dependent expression of the translationally controlled tumour protein TCTP is regulated through the PI3-K/Akt/mTORC1 signalling pathway.
Cell Signal. 2015; 27(8):1557-68 [PubMed] Related Publications
Translationally controlled tumour protein TCTP (gene symbol: TPT1) is a highly-conserved, cyto-protective protein implicated in many physiological and disease processes, in particular cancer, where it is associated with poor patient outcomes. To understand the mechanisms underlying the accumulation of high TCTP levels in cancer cells, we studied the signalling pathways that control translation of TCTP mRNA, which contains a 5'-terminal oligopyrimidine tract (5'-TOP). In HT29 colon cancer cells and in HeLa cells, serum increases the expression of TCTP two- and four-fold, respectively, and this is inhibited by rapamycin or mTOR kinase inhibitors. Polysome profiling and mRNA quantification indicate that these effects occur at the level of mRNA translation. Blocking this pathway upstream of mTOR complex 1 (mTORC1) by inhibiting Akt also prevented increases in TCTP levels in both HeLa and HT29 colon cancer cells, whereas knockout of TSC2, a negative regulator of mTORC1, led to derepression of TCTP synthesis under serum starvation. Overexpression of eIF4E enhanced the polysomal association of the TCTP mRNA, although it did not protect its translation from inhibition by rapamycin. Conversely, expression of a constitutively-active mutant of the eIF4E inhibitor 4E-BP1, which is normally inactivated by mTORC1, inhibited TCTP mRNA translation in HEK293 cells. Our results demonstrate that TCTP mRNA translation is regulated by signalling through the PI3-K/Akt/mTORC1 pathway. This explains why TCTP levels are frequently increased in cancers, since mTORC1 signalling is hyperactive in ~80% of tumours.

Trinh B, Ko SY, Haria D, et al.
The homeoprotein DLX4 controls inducible nitric oxide synthase-mediated angiogenesis in ovarian cancer.
Mol Cancer. 2015; 14:97 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Homeobox genes encode transcription factors that control patterning of virtually all organ systems including the vasculature. Tumor angiogenesis is stimulated by several homeobox genes that are overexpressed in tumor cells, but the mechanisms of these genes are poorly understood. In this study, we investigated the mechanisms by which DLX4, a homeobox gene that is associated with increased tumor microvessel density, stimulates ovarian tumor angiogenesis.
METHODS: Expression of DLX4 and nitric oxide synthases was analyzed in publicly available transcriptional profiles of ovarian cancer clinical specimens. Levels of inducible nitric oxide synthase (iNOS) were evaluated by quantitative RT-PCR, flow cytometry and nitric oxide assays using ovarian cancer cell lines in which DLX4 was overexpressed or knocked down. Signal Transducer and Activator of Transcription 1 (STAT1) expression and activity were evaluated by luciferase reporter assays, immunofluorescence staining, Western blot and immunoprecipitation. Endothelial cell growth and tumor angiogenesis were evaluated in in vitro assays and xenograft models.
RESULTS: We identified that DLX4 induces expression of iNOS, an enzyme that stimulates angiogenesis by generating nitric oxide. Analysis of datasets of two independent patient cohorts revealed that high DLX4 expression in ovarian cancer is strongly associated with elevated expression of iNOS but not of other nitric oxide synthases. Studies using STAT1-expressing and STAT1-deficient cells revealed that DLX4 interacts with STAT1 and induces iNOS expression in part by stimulating STAT1 activity. Expression of DLX4 in ovarian cancer cells stimulated endothelial cell growth in vitro and increased microvessel density in xenograft models, and these stimulatory effects of DLX4 were abrogated when its induction of iNOS was inhibited.
CONCLUSION: These findings indicate that DLX4 promotes ovarian tumor angiogenesis in part by stimulating iNOS expression.

Tasioudi KE, Sakellariou S, Levidou G, et al.
Immunohistochemical and molecular analysis of PI3K/AKT/mTOR pathway in esophageal carcinoma.
APMIS. 2015; 123(8):639-47 [PubMed] Related Publications
Among the numerous signaling pathways involved in tumorigenesis, PI3K-AKT-mTOR is a key one that regulates diverse cellular functions. However, its prognostic value in esophageal carcinoma remains unclear. In our study, we examined the immunohistochemical expression of phosphorylated (p-) AKT, mTOR, p70S6K and 4E-BP1 along with the mutational status of PIK3CA and AKT1 genes by High Resolution Melting Analysis and Pyrosequencing in 44 esophageal carcinomas. The results were correlated with the clinicopathological characteristics of the patients in an effort to define their possible prognostic significance. Total p-mTOR cytoplasmic expression, assessed in 10 random areas, was positively correlated with tumor stage (Kruskal-Wallis ANOVA, I/II vs III/IV, p = 0.0500). Μoreover, maximum p-mTOR cytoplasmic immunoexpression, estimated in hot spot areas, was positively associated with tumor grade (Mann-Whitney U test, I/II vs III, p = 0.0565). Interestingly, p-4E-BP1 immunoreactivity was negatively correlated with tumor histological grade (Mann-Whitney U test, I/II vs III, p = 0.0427). No mutation was observed in exons 9 and 20 of PIK3CA gene and in exon 4 of AKT1 gene. In conclusion, our findings depict the presence of activated PI3K/AKT/mTOR pathway in esophageal cancer bringing forward p-mTOR and p-4E-BP1 for their potential role in esophageal carcinogenesis. Additional studies are warranted to validate our findings.

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