Gene Summary

Gene:HTATIP2; HIV-1 Tat interactive protein 2
Aliases: CC3, TIP30, SDR44U1
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:oxidoreductase HTATIP2
Source:NCBIAccessed: 09 March, 2017


What does this gene/protein do?
Show (17)

Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 10 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.

  • Neoplasm Invasiveness
  • Acetyltransferases
  • Hepatocellular Carcinoma
  • Gene Expression Profiling
  • Lung Cancer
  • Molecular Sequence Data
  • Cell Movement
  • Cell Proliferation
  • beta Catenin
  • Prostate Cancer
  • Immunohistochemistry
  • alpha Karyopherins
  • Tumor Suppressor Gene
  • Tumor Suppressor Proteins
  • Lymphatic Metastasis
  • Liver Cancer
  • Base Sequence
  • Down-Regulation
  • Oligonucleotide Array Sequence Analysis
  • Chromosome 11
  • Apoptosis
  • Transcription Factors
  • DNA Methylation
  • siRNA
  • Neoplasm Metastasis
  • Breast Cancer
  • Mice, Inbred BALB C
  • Promoter Regions
  • Squamous Cell Carcinoma
  • Messenger RNA
  • Neoplastic Cell Transformation
  • Ubiquitin-Protein Ligases
  • Disease Progression
  • Missense Mutation
  • Cancer Gene Expression Regulation
  • Signal Transduction
  • Transcription Factors, TFII
  • Transfection
  • tat Gene Products, Human Immunodeficiency Virus
Tag cloud generated 09 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (4)

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: HTATIP2 (cancer-related)

Stelma T, Chi A, van der Watt PJ, et al.
Targeting nuclear transporters in cancer: Diagnostic, prognostic and therapeutic potential.
IUBMB Life. 2016; 68(4):268-80 [PubMed] Related Publications
The Karyopherin superfamily is a major class of soluble transport receptors consisting of both import and export proteins. The trafficking of proteins involved in transcription, cell signalling and cell cycle regulation among other functions across the nuclear membrane is essential for normal cellular functioning. However, in cancer cells, the altered expression or localization of nuclear transporters as well as the disruption of endogenous nuclear transport inhibitors are some ways in which the Karyopherin proteins are dysregulated. The value of nuclear transporters in the diagnosis, prognosis and treatment of cancer is currently being elucidated with recent studies highlighting their potential as biomarkers and therapeutic targets.

You A, Cao M, Guo Z, et al.
Metformin sensitizes sorafenib to inhibit postoperative recurrence and metastasis of hepatocellular carcinoma in orthotopic mouse models.
J Hematol Oncol. 2016; 9:20 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Sorafenib is recognized as a standard treatment for advanced hepatocellular carcinoma (HCC). However, many patients have to adopt dose reduction or terminate the use of sorafenib because of side effects. In addition, a large number of patients are resistant to sorafenib. Thus, it is essential to investigate the underlying mechanisms of the resistance to sorafenib and seek potential strategy to enhance its efficacy.
METHODS: The protein expression of hypoxia-inducible factors (HIF)-2α, 30-kDa HIV Tat-interacting protein (TIP30), E-cadherin, N-cadherin, and pAMPK was detected by Western blot. Cell viability assays were performed to study the influence of metformin and sorafenib on cell proliferation. Annexin V-FITC apoptosis assays were used to detect the influence of metformin and sorafenib on cell apoptosis. The relationship between HIF-2α and TIP30 was studied using gene silencing approach and chromatin immunoprecipitation assay. To investigate the effect of metformin and sorafenib on postoperative recurrence and lung metastasis of HCC in tumor-bearing mice, the mice were orally treated either with metformin or sorafenib once a day for continuous 37 days after the operation to remove the lobe where the tumor was implanted. CD31, Ki67, and TUNEL were examined by immunohistochemistry.
RESULTS: Our study demonstrated that metformin synergized with sorafenib reduced HIF-2α expression as examined by Western blot. Gene silencing approach indicated TIP30 was upregulated after knocking-down of HIF-2α and chromatin immunoprecipitation assay revealed that HIF-2α could bind to TIP30 promoter under hypoxic condition. Cell Counting Kit-8 (CCK8) cell viability assay and Annexin V-FITC apoptosis assay showed that metformin in combination with sorafenib suppressed cell proliferation and promoted cell apoptosis. Besides, combined therapy suppressed epithelial-mesenchymal transition (EMT) process both in vitro and in vivo. Moreover, metformin in combination with sorafenib significantly minimized postoperative recurrence and lung metastasis of HCC in orthotopic mouse model. Combined therapy inhibited CD31 and Ki67 expression but promoted TUNEL expression.
CONCLUSIONS: Metformin may potentially enhance the effect of sorafenib to inhibit HCC recurrence and metastasis after liver resection by regulating the expression of HIF-2α and TIP30.

Guo Z, Cao M, You A, et al.
Metformin inhibits the prometastatic effect of sorafenib in hepatocellular carcinoma by upregulating the expression of TIP30.
Cancer Sci. 2016; 107(4):507-13 [PubMed] Free Access to Full Article Related Publications
We previously found that a low dose of sorafenib had a prometastatic effect on hepatocellular carcinoma (HCC), which was caused by downregulation of TIP30 expression. More recently, metformin has been shown to have potential as a preventive and therapeutic agent for different cancers, including HCC. This study evaluated whether the combination of sorafenib and metformin is sufficient to revert the expression of TIP30, thereby simultaneously reducing lung metastasis and improving survival. Our data show that the combination of sorafenib and metformin inhibits proliferation and invasion in vitro, prolongs median survival, and reduces lung metastasis of HCC in vivo. This effect is closely associated with the upregulation of TIP30, partly through activating AMP-activated protein kinase. Thioredoxin, a prometastasis factor, is negatively regulated by TIP30 and plays an essential role during the process of HCC metastasis. Overall, our results suggest that metformin might be a potent enhancer for the treatment of HCC by using sorafenib.

Yu X, Li Z, Wu WK
TIP30: A Novel Tumor-Suppressor Gene.
Oncol Res. 2014; 22(5-6):339-48 [PubMed] Related Publications
TIP30/CC3 was first identified and characterized as a "candidate" tumor-suppressor gene in 1997. Recently, the TIP30 tumor-suppressor status has been fully established since several studies have described that TIP30 protein expression is frequently downregulated in diverse types of human tumors, and the downregulation is often associated with tumor progression. TIP30 is involved in the control of cell apoptosis, growth, metastasis, angiogenesis, DNA repair, and tumor cell metabolism. Moreover, TIP30(-/-) mice spontaneously develop hepatocellular carcinoma and other tumors at a higher incidence than that of wild-type mice. In this review, we provide an overview of current knowledge concerning the role of TIP30 in tumor development and progression. To our knowledge, this is the first review about the role of novel tumor-suppressor gene TIP30 in tumor development and progression.

Karginova O, Siegel MB, Van Swearingen AE, et al.
Efficacy of Carboplatin Alone and in Combination with ABT888 in Intracranial Murine Models of BRCA-Mutated and BRCA-Wild-Type Triple-Negative Breast Cancer.
Mol Cancer Ther. 2015; 14(4):920-30 [PubMed] Free Access to Full Article Related Publications
Patients with breast cancer brain metastases have extremely limited survival and no approved systemic therapeutics. Triple-negative breast cancer (TNBC) commonly metastasizes to the brain and predicts poor prognosis. TNBC frequently harbors BRCA mutations translating to platinum sensitivity potentially augmented by additional suppression of DNA repair mechanisms through PARP inhibition. We evaluated brain penetrance and efficacy of carboplatin ± the PARP inhibitor ABT888, and investigated gene-expression changes in murine intracranial TNBC models stratified by BRCA and molecular subtype status. Athymic mice were inoculated intracerebrally with BRCA-mutant: SUM149 (basal), MDA-MB-436 (claudin-low); or BRCA-wild-type (wt): MDA-MB-468 (basal), MDA-MB-231BR (claudin-low). TNBC cells were treated with PBS control [intraperitoneal (IP), weekly], carboplatin (50 mg/kg/wk, IP), ABT888 (25 mg/kg/d, oral gavage), or their combination. DNA damage (γ-H2AX), apoptosis (cleaved caspase-3, cC3), and gene expression were measured in intracranial tumors. Carboplatin ± ABT888 significantly improved survival in BRCA-mutant intracranial models compared with control, but did not improve survival in BRCA-wt intracranial models. Carboplatin + ABT888 revealed a modest survival advantage versus carboplatin in BRCA-mutant models. ABT888 yielded a marginal survival benefit in the MDA-MB-436, but not in the SUM149 model. BRCA-mutant SUM149 expression of γ-H2AX and cC3 proteins was elevated in all treatment groups compared with control, whereas BRCA-wt MDA-MB-468 cC3 expression did not increase with treatment. Carboplatin treatment induced common gene-expression changes in BRCA-mutant models. Carboplatin ± ABT888 penetrates the brain and improves survival in BRCA-mutant intracranial TNBC models with corresponding DNA damage and gene-expression changes. Combination therapy represents a potential promising treatment strategy for patients with TNBC brain metastases warranting further clinical investigation.

Dong X, Deng Q, Nie X, et al.
Downregulation of HTATIP2 expression is associated with promoter methylation and poor prognosis in glioma.
Exp Mol Pathol. 2015; 98(2):192-9 [PubMed] Related Publications
Glioma is an aggressive tumor with poor prognosis. Identification of precise prognostic marker and effective therapeutic target is important in the treatment of glioma. HTATIP2 is a novel tumor suppressor gene, which is frequently silenced by epigenetic mechanisms in many caners. However, the expression of HTATIP2 and how it is regulated in glioma are unknown. Hence, we assessed whether loss of HTATIP2 expression occurs in glioma, and, if so, what is the mechanism of such loss. We found that HTATIP2 expression was absent or diminished in primary gliomas compared with normal brain tissue. In vitro experiments showed that HTATIP2 expression could be restored via 5-aza-2'deoxycytidine treatment in U87 and U251 cell lines. Methyl-specific PCR indicated that the two cell lines and 60% primary gliomas carried aberrant methylated HTATIP2 alleles while normal brain tissue did not. Pyrosequencing confirmed these results and showed a higher density of methylation in the minimal promoter element, which contains four Sp1 binding sites in primary gliomas, than in normal brain tissue. Finally, we found that the overall survival was significantly higher in patients with positive HTATIP2 expression than those with loss of HTATIP2 expression. Overexpression of HTATIP2 inhibited glioma proliferation and growth in vitro. Taken together, the present study showed that loss of HTATIP2 expression was a frequent event in glioma and is associated with poor prognosis. Promoter methylation may be an underlying mechanism.

Bu F, Liu X, Li J, et al.
TGF-β1 induces epigenetic silence of TIP30 to promote tumor metastasis in esophageal carcinoma.
Oncotarget. 2015; 6(4):2120-33 [PubMed] Free Access to Full Article Related Publications
TGF-β1, a potent EMT (epithelial-mesenchymal transition) inducer present in the tumor microenvironment, is involved in the metastasis and progression of various carcinomas, including esophageal squamous cell carcinoma (ESCC). TIP30 (30kDa HIV-1 Tat interacting protein) is a putative tumor metastasis suppressor. Here, we found TIP30 was decreased in cells undergoing EMT induced by TGF-β1, an occurrence that was related to promoter hypermethylation. TGF-β1 induced TIP30 hypermethylation via increasing DNMT1 and DNMT3A expression, which could be restored by TGF-β antibodies. In our in vitro and in vivo studies, we showed that silence of TIP30 led to EMT, enhanced migrative and invasive abilities of ESCC cells, promoted tumor metastasis in xenografted mice; alternatively, overexpression of TIP30 inhibited TGF-β1-induced EMT, and metastatic abilities of ESCC cells. Mechanically, TIP30 silencing induced the nuclear translocation and transcriptional activation of β-catenin in an AKT-dependent manner, which further resulted in the initiation of EMT. Consistently, TIP30 was frequently methylated and downregulated in ESCC patients. Loss of TIP30 correlated with nuclear β-catenin and aberrant E-cadherin expression. TIP30 was a powerful marker in predicting the prognosis of ESCC. Taken together, our results suggest a novel and critical role of TIP30 involved in TGF-β1-induced activation of AKT/β-catenin signaling and ESCC metastasis.

Dong W, Shen R, Cheng S
Reduction of TIP30 in esophageal squamous cell carcinoma cells involves promoter methylation and microRNA-10b.
Biochem Biophys Res Commun. 2014; 453(4):772-7 [PubMed] Related Publications
TIP30 is a putative tumor suppressor that can promote apoptosis and inhibit angiogenesis. However, the role of TIP30 in esophageal squamous cell carcinoma (ESCC) biology has not been investigated. Immunohistochemistry was used to investigate the expression of TIP30 in 70 ESCC. Hypermethylation of TIP30 was evaluated by the methylation specific PCR (MSP) method in ESCC (tumor and paired adjacent non-tumor tissues). Lost expression of TIP30 was observed in 50 of 70 (71.4%) ESCC. 61.4% (43 of 70) of primary tumors analyzed displayed TIP30 hypermethylation, indicating that this aberrant characteristic is common in ESCC. Moreover, a statistically significant inverse association was found between TIP30 methylation status and expression of the TIP30 protein in tumor tissues (p=0.001). We also found that microRNA-10b (miR-10b) targets a homologous DNA region in the 3'untranslated region of the TIP30 gene and represses its expression at the transcriptional level. Reporter assay with 3'UTR of TIP30 cloned downstream of the luciferase gene showed reduced luciferase activity in the presence of miR-10b, providing strong evidence that miR-10b is a direct regulator of TIP30. These results suggest that TIP30 expression is regulated by promoter methylation and miR-10b in ESCC.

Shuai S, Yan X, Zhang J, et al.
TIP30 nuclear translocation negatively regulates EGF-dependent cyclin D1 transcription in human lung adenocarcinoma.
Cancer Lett. 2014; 354(1):200-9 [PubMed] Related Publications
Aberrant epidermal growth factor (EGF)-dependent signaling plays a key role in the progression of human carcinomas. We found that TIP30, a tumor suppressor protein, translocated into the nucleus of human lung adenocarcinoma cells following EGF treatment, and the selective inhibitors of EGFR signaling pathways blocked this effect. Chromatin immunoprecipitation assays revealed that TIP30 negatively regulated EGF-dependent transcriptional activation of CCND1 through a HDAC1-dependent mechanism. In lung adenocarcinoma patients, the level of nuclear TIP30 was inversely correlated with that of EGFR and cyclin D1. These findings suggest that nuclear TIP30-induced downregulation of cyclin D1 transcription antagonizes EGFR signaling and suppresses tumorigenesis.

Chen F, Li A, Gao S, et al.
Tip30 controls differentiation of murine mammary luminal progenitor to estrogen receptor-positive luminal cell through regulating FoxA1 expression.
Cell Death Dis. 2014; 5:e1242 [PubMed] Free Access to Full Article Related Publications
Estrogen receptor-alpha positive (ER(+)) breast cancers comprise the majority of human breast cancers, but molecular mechanisms underlying this subtype of breast cancers remain poorly understood. Here, we show that ER(+) mammary luminal tumors arising in Tip30(-/-)MMTV-Neu mice exhibited increased enrichment of luminal progenitor gene signature. Deletion of the Tip30 gene increased proportion of mammary stem and progenitor cell populations, and raised susceptibility to ER(+) mammary luminal tumors in female Balb/c mice. Moreover, Tip30(-/-) luminal progenitors displayed increases in propensity to differentiate to mature ER(+) luminal cells and FoxA1 expression. Knockdown of FoxA1 expression in Tip30(-/-) progenitors by shRNA specific for FoxA1 reduced their differentiation toward ER(+) mature luminal cells. Taken together, our results suggest that TIP30 is a key regulator for maintaining ER(+) and ER(-)luminal pools in the mammary luminal lineage, and loss of it promotes expansion of ER(+) luminal progenitors and mature cells and ER(+) mammary tumorigenesis.

Zhu M, Yin F, Fan X, et al.
Decreased TIP30 promotes Snail-mediated epithelial-mesenchymal transition and tumor-initiating properties in hepatocellular carcinoma.
Oncogene. 2015; 34(11):1420-31 [PubMed] Related Publications
The poor prognosis of hepatocellular carcinoma (HCC) is mainly due to tumor recurrence and metastases. Recently, epithelial-mesenchymal transition (EMT) has been implicated in tumor invasion and metastasis. However, the underlying molecular mechanisms are yet to be elucidated. Here, we show that 30-kDa Tat-interacting protein (TIP30), also called CC3, is significantly downregulated during transforming growth factor-β-induced EMT. In our in vitro and in vivo studies, we show that decreased TIP30 expression leads to EMT, as well as enhanced motility and invasion of HCC cells. Also, increased self-renewal ability and chemotherapeutic resistance are observed with TIP30 depletion. Moreover, Snail is one of the key transcription factors promoting EMT, and overexpression of TIP30 greatly decreased nucleic accumulation in Snail through the regulation of intracellular localization. Small interfering RNAs targeting Snail attenuated EMT and tumor-initiating properties induced by TIP30 deficiency. We further confirmed that TIP30 competitively interrupted the interaction of Snail with importin-β2 to block the nuclear import of Snail. Consistently, TIP30 expression significantly correlates with E-cadherin expression in HCC patients. TIP30 or combination of E-cadherin is a powerful marker in predicting the prognosis of HCC. Taken together, our results suggest a novel and critical role of TIP30 involved in HCC progression and aggressiveness.

Ouyang H, Gore J, Deitz S, Korc M
microRNA-10b enhances pancreatic cancer cell invasion by suppressing TIP30 expression and promoting EGF and TGF-β actions.
Oncogene. 2014; 33(38):4664-74 [PubMed] Free Access to Full Article Related Publications
Increased microRNA-10b (miR-10b) expression in the cancer cells in pancreatic ductal adenocarcinoma (PDAC) is a marker of disease aggressiveness. In the present study, we determined that plasma miR-10b levels are significantly increased in PDAC patients by comparison with normal controls. By gene profiling, we identified potential targets downregulated by miR-10b, including Tat-interacting protein 30 (TIP30). Immunoblotting and luciferase reporter assays confirmed that TIP30 was a direct miR-10b target. Downregulation of TIP30 by miR-10b or siRNA-mediated silencing of TIP30 enhanced epidermal growth factor (EGF)-dependent invasion. The actions of miR-10b were abrogated by expressing a modified TIP30 cDNA resistant to miR-10b. EGF-induced EGF receptor (EGFR) tyrosine phosphorylation and extracellular signal-regulated kinase phosphorylation were enhanced by miR-10b, and these effects were mimicked by TIP30 silencing. The actions of EGF in the presence of miR-10b were blocked by EGFR kinase inhibition with erlotinib and by dual inhibition of PI3K (phosphatidylinositol 3'-kinase) and MEK. Moreover, miR-10b, EGF and transforming growth factor-beta (TGF-β) combined to markedly increase cell invasion, and this effect was blocked by the combination of erlotinib and SB505124, a type I TGF-β receptor inhibitor. miR-10b also enhanced the stimulatory effects of EGF and TGF-β on cell migration and epithelial-mesenchymal transition (EMT) and decreased the expression of RAP2A, EPHB2, KLF4 and NF1. Moreover, miR-10b overexpression accelerated pancreatic cancer cell (PCC) proliferation and tumor growth in an orthotopic model. Thus, plasma miR-10b levels may serve as a diagnostic marker in PDAC, whereas intra-tumoral miR-10b promotes PCC proliferation and invasion by suppressing TIP30, which enhances EGFR signaling, facilitates EGF-TGF-β cross-talk and enhances the expression of EMT-promoting genes, whereas decreasing the expression of several metastasis-suppressing genes. Therefore, therapeutic targeting of miR-10b in PDAC may interrupt growth-promoting deleterious EGF-TGF-β interactions and antagonize the metastatic process at various levels.

Kumtepe Y, Halici Z, Sengul O, et al.
High serum HTATIP2/TIP30 level in serous ovarian cancer as prognostic or diagnostic marker.
Eur J Med Res. 2013; 18:18 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Human HIV-1 TAT interactive protein 2 (HTATIP2/TIP30) is an evolutionarily conserved gene that is expressed ubiquitously in human tissues and some tumor tissues. This protein has been found to be associated with some gynecological cancers; as such, this study aimed to investigate blood HTATIP2/TIP30 levels in patients with ovarian cancer.
METHODS: Twenty-three women with ovarian cancer and 18 patients with various non-cancerous gynecological complaints (for example, dysfunctional uterine bleeding, fibroids, and urinary incontinence) were included in the study. The pathological diagnosis of ovarian cancer was adenocarcinoma. HTATIP2/TIP30 concentration in the patients' blood samples was determined using ELISA kits.
RESULTS: The HTATIP2/TIP30 level was significantly higher in the cancer group than in the control group (1.84 ± 0.82 versus 0.57 ± 0.13 ng/ml, mean ± SD).
CONCLUSIONS: We demonstrated the potential role of HTATIP2/TIP30 in ovarian cancer for the first time, thereby enlightening future studies targeting HTATIP2/TIP30 in ovarian cancer treatment, diagnosis, and prevention.

Lu L, Sun HC, Zhang W, et al.
Aspirin minimized the pro-metastasis effect of sorafenib and improved survival by up-regulating HTATIP2 in hepatocellular carcinoma.
PLoS One. 2013; 8(5):e65023 [PubMed] Free Access to Full Article Related Publications
BACKGROUND AIMS: We previously demonstrated the pro-metastasis effect of sorafenib in hepatocellular carcinoma (HCC), which is mediated by down-regulation of tumor suppressor HTATIP2. The aim of the present study was to determine whether aspirin minimizes this effect and improves survival.
METHODS: The effects of sorafenib, aspirin, and combined sorafenib and aspirin were observed in HCCLM3 and HepG2 xenograft nude mice. Tumor growth, intrahepatic metastasis (IHM), lung metastasis, and survival were assessed. Polymerase chain reaction (PCR) array, real-time (RT)-PCR, and Western blotting were used to examine gene expression. The anti-invasion and anti-metastasis effects of aspirin were studied in HTATIP2-knockdown and HTATIP2-overexpressing HCC cell lines. The molecular mechanism of HTATIP2 regulation by aspirin was explored.
RESULTS: Aspirin suppressed the pro-invasion and pro-metastasis effects of sorafenib in HCC and up-regulated HTATIP2 expression. Aspirin did not inhibit the proliferation of HCC cells, but it decreased the invasiveness of HCC with lower expression of HTATIP2 and increased expression of a set of markers, indicating a mesenchymal-to-epithelial transition in tumor cells. The up-regulation of HTATPI2 expression by aspirin is most likely mediated through inhibition of cyclooxygenase (COX) 2 expression.
CONCLUSIONS: Aspirin minimized the pro-metastasis effect of sorafenib by up-regulating the tumor suppressor HTATIP2; this mechanism is mediated through inhibition of COX2.

Omaruddin RA, Roland TA, Wallace HJ, Chaudhry MA
Gene expression as a biomarker for human radiation exposure.
Hum Cell. 2013; 26(1):2-7 [PubMed] Related Publications
Accidental exposure to ionizing radiation can be unforeseen, rapid, and devastating. The detonation of a radiological device leading to such an exposure can be detrimental to the exposed population. The radiation-induced damage may manifest as acute effects that can be detected clinically or may be more subtle effects that can lead to long-term radiation-induced abnormalities. Accurate identification of the individuals exposed to radiation is challenging. The availability of a rapid and effective screening test that could be used as a biomarker of radiation exposure detection is mandatory. We tested the suitability of alterations in gene expression to serve as a biomarker of human radiation exposure. To develop a useful gene expression biomonitor, however, gene expression changes occurring in response to irradiation in vivo must be measured directly. Patients undergoing radiation therapy provide a suitable test population for this purpose. We examined the expression of CC3, MADH7, and SEC PRO in blood samples of these patients before and after radiotherapy to measure the in vivo response. The gene expression after ionizing radiation treatment varied among different patients, suggesting the complexity of the response. The expression of the SEC PRO gene was repressed in most of the patients. The MADH7 gene was found to be upregulated in most of the subjects and could serve as a molecular marker of radiation exposure.

Zhang W, Sun HC, Wang WQ, et al.
Sorafenib down-regulates expression of HTATIP2 to promote invasiveness and metastasis of orthotopic hepatocellular carcinoma tumors in mice.
Gastroenterology. 2012; 143(6):1641-1649.e5 [PubMed] Related Publications
BACKGROUND & AIMS: Antiangiogenic agents can sometimes promote tumor invasiveness and metastasis, but little is known about the effects of the antiangiogenic drug sorafenib on progression of hepatocellular carcinoma (HCC).
METHODS: Sorafenib was administered orally (30 mg · kg(-1) · day(-1)) to mice with orthotopic tumors grown from HCC-LM3, SMMC7721, or HepG2 cells. We analyzed survival times of mice, along with tumor growth, metastasis within liver and to lung, and induction of the epithelial-mesenchymal transition. Polymerase chain reaction arrays were used to determine the effects of sorafenib on gene expression patterns in HCC cells. We analyzed regulation of HIV-1 Tat interactive protein 2 (HTATIP2) by sorafenib and compared levels of this protein in tumor samples from 75 patients with HCC (21 who received sorafenib after resection and 54 who did not).
RESULTS: Sorafenib promoted invasiveness and the metastatic potential of orthotopic tumors grown from SMMC7721 and HCC-LM3 cells but not from HepG2 cells. In gene expression analysis, HTATIP2 was down-regulated by sorafenib. HCC-LM3 cells that expressed small hairpin RNAs against HTATIP2 (knockdown) formed less invasive tumors in mice following administration of sorafenib than HCC-LM3 without HTATIP2 knockdown. Alternatively, HepG2 cells that expressed transgenic HTATIP2 formed more invasive tumors in mice following administration of sorafenib. Sorafenib induced the epithelial-mesenchymal transition in HCC cell lines, which was associated with expression of HTATIP2. Sorafenib regulated expression of HTATIP2 via Jun-activated kinase (JAK) and signal transducer and activator of transcription (STAT)3 signaling. Sorafenib therapy prolonged recurrence-free survival in patients who expressed lower levels of HTATIP2 compared with higher levels.
CONCLUSIONS: Sorafenib promotes invasiveness and the metastatic potential of orthotopic tumors from HCC cells in mice, down-regulating expression of HTATIP2 via JAK-STAT3 signaling.

Li A, Zhang C, Gao S, et al.
TIP30 loss enhances cytoplasmic and nuclear EGFR signaling and promotes lung adenocarcinogenesis in mice.
Oncogene. 2013; 32(18):2273-81, 2281e.1-12 [PubMed] Free Access to Full Article Related Publications
Lung adenocarcinoma, the most common type of human non-small cell lung cancer (NSCLC), frequently overexpresses epidermal growth factor receptor (EGFR). However, the mechanisms underlying EGFR overexpression are not completely understood. Recent studies have identified that decreased expression of TIP30 (30kDa HIV-1 Tat interacting protein) is associated with the metastasis of human NSCLCs, but a causative relationship between TIP30 deficiency and NSCLC development remains unclear. We show here that Tip30 deletion leads to spontaneous development of lung adenomas and adenocarcinomas in mice. Lung tumor development was preceded by aberrant expansion of bronchioalveolar stem/progenitor and alveolar type II (AT2) cells, and also increased expression of EGFR and its downstream signaling factors in the lung of Tip30(-/-) mice. Moreover, TIP30 knockdown in human lung adenocarcinoma cells resulted in prolonged EGFR activity in early endosomes, delayed EGFR degradation, increased EGFR nuclear localization, leading to upregulated pAKT and pERK1/2 expression. Importantly, in human lung adenocarcinomas, low TIP30 expression correlates with prolonged patient overall and post-progression survival times. Together, these results suggest that TIP30 functions as a tumor suppressor to inhibit EGFR cytoplasmic and nuclear signaling and suppress adenocarcinogenesis in the lung, and highlight the potential of therapeutic strategies aiming at inhibiting EGFR signaling for patients with low TIP30-expression lung adenocarcinoma.

Wierinckx A, Roche M, Raverot G, et al.
Integrated genomic profiling identifies loss of chromosome 11p impacting transcriptomic activity in aggressive pituitary PRL tumors.
Brain Pathol. 2011; 21(5):533-43 [PubMed] Related Publications
Integrative genomics approaches associating DNA structure and transcriptomic analysis should allow the identification of cascades of events relating to tumor aggressiveness. While different genome alterations have been identified in pituitary tumors, none have ever been correlated with the aggressiveness. This study focused on one subtype of pituitary tumor, the prolactin (PRL) pituitary tumors, to identify molecular events associated with the aggressive and malignant phenotypes. We combined a comparative genomic hybridization and transcriptomic analysis of 13 PRL tumors classified as nonaggressive or aggressive. Allelic loss within the p arm region of chromosome 11 was detected in five of the aggressive tumors. Allelic loss in the 11q arm was observed in three of these five tumors, all three of which were considered as malignant based on the occurrence of metastases. Comparison of genomic and transcriptomic data showed that allelic loss impacted upon the expression of genes located in the imbalanced region. Data filtering allowed us to highlight five deregulated genes (DGKZ, CD44, TSG101, GTF2H1, HTATIP2), within the missing 11p region, potentially responsible for triggering the aggressive and malignant phenotypes of PRL tumors. Our combined genomic and transcriptomic analysis underlines the importance of chromosome allelic loss in determining the aggressiveness and malignancy of tumors.

Arai Y, Honda S, Haruta M, et al.
Genome-wide analysis of allelic imbalances reveals 4q deletions as a poor prognostic factor and MDM4 amplification at 1q32.1 in hepatoblastoma.
Genes Chromosomes Cancer. 2010; 49(7):596-609 [PubMed] Related Publications
In a single-nucleotide polymorphism array-based analysis of 56 hepatoblastoma (HB) tumors, allelic imbalances were detected in 37 tumors (66%). Chromosome gains were found in 1q (28 tumors), 2q (24), 6p (8), 8q (8), 17q (6), and 20pq (10), and losses in 1p (6), 4q (9), and 16q (4). Fine mapping delineated the shortest overlapping region (SOR) of gains at 1q32.1 (1.3 Mb) and 2q24.2-q24.3 (4.8 Mb), and losses at 4q34.3-q35.2 (8.7 Mb) and 4q32.3 (1.6 Mb). Uniparental disomy of 11pter-11p15.4 (IGF2) and loss of 11pter-p14.1 were found in 11 and 2 tumors, respectively. Expression of HTATIP2 (11p15.1) was absent in 9 of 20 tumors. Amplification was identified in four tumors at 1q32.1, where the candidate oncogene MDM4 is located. In the 4q32.3-SRO, ANXA10S, a variant of the candidate tumor suppressor ANXA10, showed no expression in 19 of 24 tumors. Sequence analysis of ANXA10S identified a missense mutation (E36K, c.106G>A) in a HB cell line. Multivariate analysis revealed that both 4q deletion and RASSF1A methylation (relative risks: 4.21 and 7.55, respectively) are independent prognostic factors. Our results indicate that allelic imbalances and gene expression patterns provide possible diagnostic and prognostic markers, as well as therapeutic targets in a subset of HB.

Swift S, Xu J, Trivedi V, et al.
A novel protease-activated receptor-1 interactor, Bicaudal D1, regulates G protein signaling and internalization.
J Biol Chem. 2010; 285(15):11402-10 [PubMed] Free Access to Full Article Related Publications
Protease-activated receptor-1 (PAR1) is a G protein-coupled receptor that plays critical roles in cancer, angiogenesis, inflammation, and thrombosis. Proteolytic cleavage of the extracellular domain of PAR1 generates a tethered ligand that activates PAR1 in an unusual intramolecular mode. The signal emanating from the irreversibly cleaved PAR1 is terminated by G protein uncoupling and internalization; however, the mechanisms of PAR1 signal shut off still remain unclear. Using a yeast two-hybrid screen, we identified Bicaudal D1 (BicD1) as a direct interactor with the C-terminal cytoplasmic domain of PAR1. BICD was originally identified as an essential developmental gene associated with mRNA and Golgi-endoplasmic reticulum transport. We discovered a novel function of BicD1 in the modulation of G protein signaling, cell proliferation, and endocytosis downstream of PAR1. BicD1 and its C-terminal CC3 domain inhibited PAR1 signaling to G(q)-phospholipase C-beta through coiled-coil interactions with the cytoplasmic 8th helix of PAR1. Unexpectedly, BicD1 was also found to be a potent suppressor of PAR1-driven proliferation of breast carcinoma cells. The growth-suppressing effects of BicD1 required the ability to interact with the 8th helix of PAR1. Silencing of BicD1 expression impaired endocytosis of PAR1, and BicD1 co-localized with PAR1 and tubulin, implicating BicD1 as an important adapter protein involved in the transport of PAR1 from the plasma membrane to endosomal vesicles. Together, these findings provide a link between PAR1 signal termination and internalization through the non-G protein effector, BicD1.

Chen X, Cao X, Dong W, et al.
Expression of TIP30 tumor suppressor gene is down-regulated in human colorectal carcinoma.
Dig Dis Sci. 2010; 55(8):2219-26 [PubMed] Related Publications
PURPOSE: Human TIP30 was initially identified as a candidate metastasis suppressor gene whose expression was down-regulated in human liver, lung, breast, and prostate cancers, and recently the role of this gene was examined in colorectal cancer. The aim of this study was to determine the level of TIP30 expression in colorectal carcinoma (CRC).
RESULTS: TIP30 protein levels were lower in colorectal carcinomas compared to normal tissue from the control group (P < 0.001). The frequencies of hypermethylation of TIP30 in tumor were 36%, while there was no aberrant methylation in paired adjacent non-tumor tissue. A statistically significant inverse association was found between TIP30 methylation status and expression of the TIP30 protein in tumor tissues (P = 0.006). Somatic missense mutations in the TIP30 gene were identified in human CRC tissue specimens.
CONCLUSIONS: Our results demonstrate that promoter methylation is involved in the decreased expression of TIP30 tumor suppressor gene in human colorectal carcinoma.

Garwood ER, Kumar AS, Baehner FL, et al.
Fluvastatin reduces proliferation and increases apoptosis in women with high grade breast cancer.
Breast Cancer Res Treat. 2010; 119(1):137-44 [PubMed] Free Access to Full Article Related Publications
The purpose of this study is to determine the biologic impact of short-term lipophilic statin exposure on in situ and invasive breast cancer through paired tissue, blood and imaging-based biomarkers. A perioperative window trial of fluvastatin was conducted in women with a diagnosis of DCIS or stage 1 breast cancer. Patients were randomized to high dose (80 mg/day) or low dose (20 mg/day) fluvastatin for 3-6 weeks before surgery. Tissue (diagnostic core biopsy/final surgical specimen), blood, and magnetic resonance images were obtained before/after treatment. The primary endpoint was Ki-67 (proliferation) reduction. Secondary endpoints were change in cleaved caspase-3 (CC3, apoptosis), MRI tumor volume, and serum C-reactive protein (CRP, inflammation). Planned subgroup analyses compared disease grade, statin dose, and estrogen receptor status. Forty of 45 patients who enrolled completed the protocol; 29 had paired Ki-67 primary endpoint data. Proliferation of high grade tumors decreased by a median of 7.2% (P = 0.008), which was statistically greater than the 0.3% decrease for low grade tumors. Paired data for CC3 showed tumor apoptosis increased in 38%, remained stable in 41%, and decreased in 21% of subjects. More high grade tumors had an increase in apoptosis (60 vs. 13%; P = 0.015). Serum CRP did not change, but cholesterol levels were significantly lower post statin exposure (P < 0.001). Fluvastatin showed measurable biologic changes by reducing tumor proliferation and increasing apoptotic activity in high-grade, stage 0/1 breast cancer. Effects were only evident in high grade tumors. These results support further evaluation of statins as chemoprevention for ER-negative high grade breast cancers.

Poomthavorn P, Wong SH, Higgins S, et al.
Activation of a prometastatic gene expression program in hypoxic neuroblastoma cells.
Endocr Relat Cancer. 2009; 16(3):991-1004 [PubMed] Related Publications
The hypoxia inducible factor-1alpha (HIF1alpha) is a key regulator of oxygen homeostasis, modulating cell survival, and growth in cells exposed to hypoxia. In this study, neuroblastoma (NB) cells SH-SY5Y and SK-N-MC were employed to determine the mechanisms regulating adaptation to hypoxia. NB cells were cultured in a serum-free medium in the presence or absence of CoCl(2) (100 muM, hypoxia mimic) for up to 48 h. SH-SY5Y and SK-N-MC cell numbers were not affected by CoCl(2) treatment, while mitochondrial activity was reduced by approximately 50% in SH-SY5Y cells and by approximately 70% in SK-N-MC cells. Intracellular accumulation of HIF1alpha protein was detected as early as 30 min of post-hypoxia, followed by the increase of mRNA for vascular endothelial growth factor (VEGF) and nuclear accumulation of the ID1-2 transcription factors by 4 h. In hypoxic SH-SY5Y NB cells, real-time PCR analysis showed that the genes involved in maintenance of cell-cell and cell-matrix interactions (i.e. adenomatosis polyposis coli, E-cadherin, catenin, EphB2, fibronectin-1, HTATIP2, tissue inhibitor of metalloprotease-4) were down-regulated by up to 90%, while genes involved in enhancement of metastatic behavior (integrin a7b1, hepatocyte growth factor receptor, transforming growth factor-beta1, VEGF, kisspeptin, interleukin-1beta) were dramatically up-regulated above 200%. These changes were all consistent with the induction of epithelial-mesenchymal transition. We have thus demonstrated that NB cell adaptation to hypoxia, in addition to the modulation of HIF1alpha and VEGF expression and nuclear translocation of ID1 and ID2 transcription factors, involve in the activation of a gene expression program consistent with the pro-metastatic events. These processes are probably responsible for the NB cell transition from an adherent phenotype to a highly migratory, invasive and aggressive NB cell type.

Tong X, Li K, Luo Z, et al.
Decreased TIP30 expression promotes tumor metastasis in lung cancer.
Am J Pathol. 2009; 174(5):1931-9 [PubMed] Free Access to Full Article Related Publications
The HIV Tat-interacting protein (TIP30), also called CC3 or HTIP2, is encoded by Tip30, a putative tumor-suppressor gene located on human chromosome 11p15.1. In this study, we investigated the role of TIP30 in the progression and metastasis of lung cancer. TIP30 expression was analyzed in 206 paired lung cancers and adjacent non-tumor tissues, as well as in 70 matched lymph node metastases using a high-density tissue microarray. Results were compared with the clinicopathologic features of the patients from whom the tissues were taken. Low TIP30 expression levels were found in all 9 cases of small cell lung cancer and in 36.5% (72/197) of non-small cell lung cancer, which were correlated with lymph node metastasis in non-small cell lung cancer and with poor differentiation and advanced stage of tumor cells in squamous cell carcinoma. The immunostaining scores were significantly lower in the metastatic lesions than in the primary lesions. Down-regulation of TIP30 by a short hairpin RNA enhanced cell survival, migration, and invasion through Matrigel in vitro, and promoted lung metastasis and vascularization in nude mice. Further studies revealed that the down-regulation of TIP30 enhanced the expression of osteopontin, as well as matrix metalloproteinase-2 and vascular endothelial growth factor. Our results suggest that the down-regulation of TIP30 promotes metastatic progression of lung cancer, hence it could serve as a potential target for the development of lung cancer therapies.

Yu J, Cheng YY, Tao Q, et al.
Methylation of protocadherin 10, a novel tumor suppressor, is associated with poor prognosis in patients with gastric cancer.
Gastroenterology. 2009; 136(2):640-51.e1 [PubMed] Related Publications
BACKGROUND & AIMS: By using methylation-sensitive representational difference analysis, we identified protocadherin 10 (PCDH10), a gene that encodes a protocadherin and is silenced in a tumor-specific manner. We analyzed its epigenetic inactivation, biological effects, and prognostic significance in gastric cancer.
METHODS: Methylation status was evaluated by combined bisulfite restriction analysis and bisulfite sequencing. The effects of PCDH10 re-expression were determined in growth, apoptosis, proliferation, and invasion assays. PCDH10 target genes were identified by complementary DNA microarray analysis.
RESULTS: PCDH10 was silenced or down-regulated in 94% (16 of 17) of gastric cancer cell lines; expression levels were restored by exposure to demethylating agents. Re-expression of PCDH10 in MKN45 gastric cancer cells reduced colony formation in vitro and tumor growth in mice; it also inhibited cell proliferation (P < .01), induced cell apoptosis (P < .001), and repressed cell invasion (P < .05), up-regulating the pro-apoptosis genes Fas, Caspase 8, Jun, and CDKN1A; the antiproliferation gene FGFR; and the anti-invasion gene HTATIP2. PCDH10 methylation was detected in 82% (85 of 104) of gastric tumors compared with 37% (38 of 104) of paired nontumor tissues (P < .0001). In the latter, PCDH10 methylation was higher in precancerous lesions (27 of 45; 60%) than in chronic gastritis samples (11 of 59; 19%) (P < .0001). After a median follow-up period of 16.8 months, multivariate analysis revealed that patients with PCDH10 methylation in adjacent nontumor areas had a significant decrease in overall survival. Kaplan-Meier survival curves showed that PCDH10 methylation was associated significantly with shortened survival in stage I-III gastric cancer patients.
CONCLUSIONS: PCDH10 is a gastric tumor suppressor; its methylation at early stages of gastric carcinogenesis is an independent prognostic factor.

Lu B, Ma Y, Wu G, et al.
Methylation of Tip30 promoter is associated with poor prognosis in human hepatocellular carcinoma.
Clin Cancer Res. 2008; 14(22):7405-12 [PubMed] Related Publications
PURPOSE: To investigate Tip30 promoter methylation status in human hepatocellular carcinoma (HCC) and the correlation with clinicopathologic features and prognosis.
EXPERIMENTAL DESIGN: The methylation status of CpG islands in Tip30 promoter was examined in 15 HCC cell lines as well as 59 paired HCC and adjacent nontumor tissues. The associations between Tip30 methylation status and the survival of patients were analyzed.
RESULTS: Tip30 promoter was hypermethylated in 6 of 10 HCC cell lines with reduced Tip30 mRNA. DNA methyltransferase inhibitor, 5-aza-2'-deoxycytidine, greatly enhanced TIP30 expression and sensitized HCC cells to cytotoxic drug-induced cell death. The promoter region of Tip30 was identified and the main promoter activity was located in the -135 to -45 region sited within a CpG island. The minimal promoter element contained four Sp1 binding sites, which were hypermethylated in HCC cell-derived promoters. Moreover, analyses of Tip30 promoter methylation status in 59 paired HCC tissues showed that 47% of the cases were hypermethylated. Recurrence rate (95% versus 67%; P = 0.011) and mortality (82% versus 53%; P = 0.033) were significantly higher in patients with methylated Tip30. Disease-free survival was significantly higher in patients with unmethylated Tip30 (33.3% versus 4.5%; P = 0.036).
CONCLUSIONS: Our results show that epigenetic silencing of Tip30 gene expression by CpG island DNA hypermethylation is associated with poor prognosis in patients with HCC.

Anderton JA, Lindsey JC, Lusher ME, et al.
Global analysis of the medulloblastoma epigenome identifies disease-subgroup-specific inactivation of COL1A2.
Neuro Oncol. 2008; 10(6):981-94 [PubMed] Free Access to Full Article Related Publications
Candidate gene investigations have indicated a significant role for epigenetic events in the pathogenesis of medulloblastoma, the most common malignant brain tumor of childhood. To assess the medulloblastoma epigenome more comprehensively, we undertook a genomewide investigation to identify genes that display evidence of methylation-dependent regulation. Expression microarray analysis of medulloblastoma cell lines following treatment with a DNA methyltransferase inhibitor revealed deregulation of multiple transcripts (3%-6% of probes per cell line). Eighteen independent genes demonstrated >3-fold reactivation in all cell lines tested. Bisulfite sequence analysis revealed dense CpG island methylation associated with transcriptional silencing for 12 of these genes. Extension of this analysis to primary tumors and the normal cerebellum revealed three major classes of epigenetically regulated genes: (1) normally methylated genes (DAZL, ZNF157, ASN) whose methylation reflects somatic patterns observed in the cerebellum, (2) X-linked genes (MSN, POU3F4, HTR2C) that show disruption of their sex-specific methylation patterns in tumors, and (3) tumor-specific methylated genes (COL1A2, S100A10, S100A6, HTATIP2, CDH1, LXN) that display enhanced methylation levels in tumors compared with the cerebellum. Detailed analysis of COL1A2 supports a key role in medulloblastoma tumorigenesis; dense biallelic methylation associated with transcriptional silencing was observed in 46 of 60 cases (77%). Moreover, COL1A2 status distinguished infant medulloblastomas of the desmoplastic histopathological subtype, indicating that distinct molecular pathogenesis may underlie these tumors and their more favorable prognosis. These data reveal a more diverse and expansive medulloblastoma epi genome than previously understood and provide strong evidence that the methylation status of specific genes may contribute to the biological subclassification of medulloblastoma.

Zhao J, Lu B, Xu H, et al.
Thirty-kilodalton Tat-interacting protein suppresses tumor metastasis by inhibition of osteopontin transcription in human hepatocellular carcinoma.
Hepatology. 2008; 48(1):265-75 [PubMed] Related Publications
UNLABELLED: It has been previously demonstrated that the 30-kDa Tat-interacting protein (TIP30) plays an important role in the suppression of hepatocarcinogenesis by acting as a tumor suppressor. Here we report that TIP30 suppresses metastasis of hepatocellular carcinoma (HCC) through inhibiting the transcription of osteopontin (OPN), a key molecule in the development of tumor metastasis. The expression of TIP30 messenger RNA was reverse to that of OPN messenger RNA in HCC cell lines. Ectopic expression of TIP30 greatly suppressed OPN expression, inhibited invasion of HCC cells through extracellular matrix (ECM) and adhesion with fibronectin in vitro, whereas down-regulation of TIP30 by RNA-mediated interference enhanced OPN expression and promoted metastatic abilities of HCC cells in vitro. Moreover, overexpression of TIP30 significantly inhibited the growth and lung metastases of HCC cells in nude mice. In contrast, down-regulation of TIP30 greatly promoted tumor cell growth and metastases in vivo. TIP30 repressed OPN transcription through interaction with Ets-1 and suppressed the transcriptional activity of Ets-1 and synergistic actions of Ets-1 and alkaline phosphatase-1. Thus, TIP30 may act as an Ets-1 modulator and inhibit tumor metastasis through abrogating Ets-1-dependent transcription. Moreover, expression of TIP30 was inversely associated with OPN expression in HCC tissue samples as detected by immunohistochemistry assay.
CONCLUSION: Our results reveal a novel pathway by which OPN and possibly other Ets-1 target genes involved in tumor metastasis are regulated by TIP30 and elucidate a mechanism for metastasis promoted by TIP30 deficiency.

Zhang H, Zhang Y, Duan HO, et al.
TIP30 is associated with progression and metastasis of prostate cancer.
Int J Cancer. 2008; 123(4):810-6 [PubMed] Related Publications
Tat-interacting protein 30 (TIP30), a transcriptional repressor for ERalpha-mediated transcription, possesses several characteristics of a tumor suppressor in certain human and mouse cells. It is reported that deletion of TIP30 gene preferentially increases tumorigenesis in the female knockout mice. Here, we analyzed TIP30 gene expression in the databases of several DNA microarray studies of human prostate cancer and show that TIP30 is specifically overexpressed in metastatic prostate cancers. We demonstrate that TIP30 nuclear expression is associated with prostate cancer progression and metastasis by immunohistochemical analysis in primary and metastatic prostate cancers. Consistent with these data, we also show that knockdown of TIP30 expression, through use of a short hairpin RNA-expressing plasmid, suppresses the cellular growth of PC3 and LNCaP prostate cancer cells. Ectopic overexpression of TIP30 stimulates metastatic potential of prostate cancer cells in an in vitro invasion assay, whereas knockdown of TIP30 inhibits the prostate cancer cells invasion. Finally, we demonstrate that ectopic overexpression of TIP30 enhances androgen receptor mediated transcription, whereas knockdown of TIP30 results in a decreased transcription activity. These data provide evidence that TIP30 plays a role in prostate cancer progression and that TIP30 overexpression may promote prostate cancer cell growth and metastasis.

Singh AP, Bafna S, Chaudhary K, et al.
Genome-wide expression profiling reveals transcriptomic variation and perturbed gene networks in androgen-dependent and androgen-independent prostate cancer cells.
Cancer Lett. 2008; 259(1):28-38 [PubMed] Free Access to Full Article Related Publications
Previously, we have developed a unique in vitro LNCaP cell model, which includes androgen-dependent (LNCaP-C33), androgen-independent (LNCaP-C81) and an intermediate phenotype (LNCaP-C51) cell lines resembling the stages of prostate cancer progression to hormone independence. This model is advantageous in overcoming the heterogeneity associated with the prostate cancer up to a certain extent. We characterized and compared the gene expression profiles in LNCaP-C33 (androgen-dependent) and LNCaP-C81 (androgen-independent) cells using Affymetrix GeneChip array analyses. Multiple genes were identified exhibiting differential expression during androgen-independent progression. Among the important genes upregulated in androgen-independent cells were PCDH7, TPTE, TSPY, EPHA3, HGF, MET, EGF, TEM8, etc., whereas many candidate tumor suppressor genes (HTATIP2, CDKN2A, CDKN2B, CDKN1C, TP53, TP73, ICAM1, SOCS1/2, SPRY2, PPP2CA, PPP3CA, etc.) were decreased. Pathway prediction analysis identified important gene networks associated with growth-promoting and apoptotic signaling that were perturbed during androgen-independent progression. Further investigation of one of the genes, PPP2CA, which encodes the catalytic subunit of a serine phosphatase PP2A, a potent tumor suppressor, revealed that its expression was decreased in prostate cancer compared to adjacent normal/benign tissue. Furthermore, the downregulated expression of PPP2CA was significantly correlated with tumor stage and Gleason grade. Future studies on the identified differentially expressed genes and signaling pathways may be helpful in understanding the biology of prostate cancer progression and prove useful in developing novel prognostic biomarkers and therapy for androgen-refractory prostate cancer.

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