Deletion of Tip30 leads to rapid immortalization of murine mammary epithelial cells and ductal hyperplasia in the mammary gland

HTATIP2 Overexpression was Associated With a Good Prognosis in Gastric Cancer

Introduction: The purpose of this study was to compare the transcriptomes of poorly cohesive carcinoma (PCC; diffuse-type) and well-differentiated tubular adenocarcinoma (WD; intestinal-type) using gastric cancer (GC) tissues and cell lines and to evaluate the prognostic role of HIV-1 Tat Interactive Protein 2 (HTATIP2). Materials and Methods: We performed next-generation sequencing with 8 GC surgical samples (5 WD and 3 PCC) and 3 GC cell lines (1 WD: MKN74, and 2 PCC: KATOIII and SNU601). Immunohistochemistry was used to validate HTATIP2 expression. We performed functional analysis by HTATIP2 overexpression (OE). Kaplan-Meier survival plots and the PrognoScan database were used for survival analysis. Results: The genes with significantly reduced expression in PCC versus WD (in both tissues and cell lines) were HTATIP2, ESRP1, GRHL2, ARHGEF16, CKAP2L, and ZNF724. According to immunohistochemical staining, the HTATIP2-OE group had significantly higher number of patients with early GC (EGC) (T1) (P = .024), less lymph node (LN) metastasis (P = .008), and low TNMA stage (P = .017) than HTATIP2 underexpression (UE) group. Better survival rates were confirmed in the HTATIP2 OE group by Kaplan-Meir survival and PrognoScan analysis. In vitro, HTATIP2-OE in KATO III cells caused a significant decrease in cancer cell migration and invasion. Decreased Snail and Slug expression in HTATIP2 OE cells suggested that epithelial-mesenchymal transition is involved in this process. Conclusion: HTATIP2 might be a good prognostic marker and a candidate target for GC treatment.

Single-cell transcriptomes of mouse bladder urothelium uncover novel cell type markers and urothelial differentiation characteristics

Objectives

Much of the information to date in terms of subtypes and function of bladder urothelial cells were derived from anatomical location or by the expression of a small number of marker genes. To have a comprehensive map of the cellular anatomy of bladder urothelial cells, we performed single‐cell RNA sequencing to thoroughly characterize mouse bladder urothelium.

Materials and methods

A total of 18,917 single cells from mouse bladder urothelium were analysed by unbiased single‐cell RNA sequencing. The expression of the novel cell marker was confirmed by immunofluorescence using urinary tract infection models.

Results

Unsupervised clustering analysis identified 8 transcriptionally distinct cell subpopulations from mouse bladder urothelial cells. We discovered a novel type of bladder urothelial cells marked by Plxna4 that may be involved with host response and wound healing. We also found a group of basal‐like cells labelled by ASPM that could be the progenitor cells of adult bladder urothelium. ASPM⁺ urothelial cells are significantly increased after injury by UPEC. In addition, specific transcription factors were found to be associated with urothelial cell differentiation. At the last, a number of interstitial cystitis/bladder pain syndrome–regulating genes were found differentially expressed among different urothelial cell subpopulations.

Conclusions

Our study provides a comprehensive characterization of bladder urothelial cells, which is fundamental to understanding the biology of bladder urothelium and associated bladder disease.

Reduction of Tat-interacting Protein 30 Expression Could be a Prognostic Marker in Bladder Urothelial Cancer

Background:

Tat-interacting protein 30 (TIP30) has been reported to be a tumor suppressor, with reduced or absent expression in various tumors. However, its role in bladder urothelial cancer (BUC) has not been investigated. Therefore, herein, we investigated the expression of TIP30 protein in BUC and normal bladder mucosa and the clinical significance of TIP30 expression in the prognosis of BUC.

Methods:

We reviewed data from 79 cases of BUC and 15 adjacent tissue samples from 79 patients treated at our institution between 2004 and 2007. TIP30 expression was examined by immunohistochemistry. The relationship between TIP30 expression and tumor stage, histological grade, and survival was analyzed. Differences between groups were evaluated using the t-test or matched-pairs test, and differences in the survival rates were analyzed with the log-rank test.

Results:

TIP30 protein expression was significantly reduced in BUC tissue (t = −6.91, P < 0.05) compared with normal tissue samples, and in invasive bladder cancer (t = 10.89, P < 0.05) compared with superficial bladder cancer. TIP30 protein expression differed significantly among different differentiated groups classified either according to the World Health Organization (2004, F = 17.48, P < 0.01) or World Health Organization (1973, F = 10.68, P < 0.01). TIP30 protein expression was significantly reduced in high-grade papillary urothelial carcinoma compared with papillary urothelial neoplasm of low malignant potential (P < 0.05) and low-grade papillary urothelial carcinoma (P < 0.05). Meanwhile, TIP30 protein expression was significantly reduced in Grade III BUC, compared with Grade I (P < 0.05) and Grade II (P < 0.05). Patients with low TIP30 expression showed a higher incidence of disease progression than those with high TIP30 expression (t = 2.63, P < 0.05). Kaplan-Meier survival analysis showed a strong positive relationship between TIP30 expression and overall survival (OS) (χ² = 17.29, P < 0.05).

Conclusions:

TIP30 expression was associated with clinical tumor stage in BUC, suggesting that it might play an important role in disease progression. Furthermore, TIP30 might predict postoperative OS. Thus, its evaluation might be useful for predicting prognosis.

Role of CCN5 (WNT1 inducible signaling pathway protein 2) in pancreatic islets

In search of direct targets of insulin-like growth factor (IGF)-1 action, we discovered CCN5 (WNT1 inducible signaling pathway protein 2 [WISP2]) as a novel protein expressed in pancreatic β-cells. As a member of the "CCN" ( C ysteine-rich angiogenic inducer 61 [Cyr61], C onnective tissue growth factor [CTGF in humans], and N ephroblastoma overexpressed [Nov; in chickens]) family, the expression of CCN5/WISP2 is stimulated by IGF-1 together with Wnt signaling. When overexpressed in insulinoma cells, CCN5 promotes cell proliferation and cell survival against streptozotocin-induced cell death. The cell proliferation effect seems to be caused by AKT phosphorylation and increased cyclin D1 levels. These properties resemble those of CCN2/CTGF, another isoform of the CCN family, although CCN5 is the only one within the family of six proteins that lacks the C-terminal repeat. Treatment of primary mouse islets with recombinant CCN5 protein produced similar effects to those of gene transfection, indicating that either as a matricellular protein or a secreted growth factor, CCN5 stimulates β-cell proliferation and regeneration in a paracrine fashion. This review also discusses the regulation of CCN5/WISP2 by estrogen and its involvement in angiogenesis and tumorigenesis.

TIP30: A Novel Tumor-Suppressor Gene

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.

Contribution of TIP30 to chemoresistance in laryngeal carcinoma

Laryngeal squamous cell carcinoma (LSCC) is one of the most common carcinomas of the head and neck. Despite advances in diagnosis and treatment, the survival of patients with LSCC has not improved in the past two decades. TIP30, a newly identified tumour suppressor, appears to be involved in multiple processes during tumour development. Here, we investigated the involvement of TIP30 in chemoresistance of LSCC in vitro and in vivo. We showed that TIP30 expression decreased significantly in drug-selected cells (DSCs) of laryngeal carcinoma. Suppressing TIP30 enhanced resistance capability to multiple chemotherapy drugs, cell proliferation and self-renewal in Hep2 cells. Additionally, decreased self-renewal capacity and chemotherapeutic resistance were observed in DSCs overexpressing TIP30. Furthermore, TIP30 negatively regulated tumourigenesis and chemoresistance in LSCC cells subcutaneously transplanted into nude mice. Moreover, decreased TIP30 expression contributed to chemoresistance, self-renewal and proliferation of LSCC cells via nuclearlisation of β-catenin, a cell–cell adhesion and stem cell renewal regulator. Consistently, Kaplan–Meier and Cox proportional hazards regression modelling analyses showed that decreased TIP30 expression independently predicted poor survival in patients with LSCC. Taken together, our results reveal that TIP30 has a crucial role in chemoresistance of LSCC through the AKT/glycogen synthase kinase-3β/β-catenin signalling pathway and may be a promising candidate for improving LSCC chemotherapy.

Tip30 controls differentiation of murine mammary luminal progenitor to estrogen receptor-positive luminal cell through regulating FoxA1 expression

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.

Decreased TIP30 promotes Snail-mediated epithelial-mesenchymal transition and tumor-initiating properties in hepatocellular carcinoma

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.

Decreased TIP30 expression predicts poor prognosis in pancreatic cancer patients

Pancreatic ductal adenocarcinoma (PDAC) is known for its aggressive growth, and is characterized by early tissue invasion and metastasis with poor prognosis. Identifying prognostic markers and delineating the underlying mechanisms that promote progression of PDAC are important for the treatment of pancreatic cancer. TIP30, a newly identified tumor suppressor, appears to be involved in multiple processes during tumor development and metastasis. Here, we investigated the expression of TIP30 in PDAC and its prognostic value in PDAC patients. We examined the expression of TIP30 by immunohistochemistry in tissue microarrays containing 106 surgically resected PDAC. Kaplan-Meier analysis and Cox proportional hazards regression modeling analysis showed that TIP30 expression independently predicted better survival in pancreatectomy patients (p < 0.01). Moreover, decreased TIP30 expression was associated with lymph node metastasis (p < 0.05) and loss of E-cadherin expression (r = 0.329, p < 0.01). Suppression of TIP30 resulted in upregulation of Snail and subsequent downregulation of E-cadherin in SW1990 cells containing high-level of endogenous TIP30. However, in the PANC-1 cells containing low level of endogenous TIP30, suppressing TIP30 caused upregulation of Slug instead of Snail, followed by upregulation of MMP9 rather than E-cadherin. Taken together, our work reveals that decreased TIP30 expression is able to enhance invasion and metastasis of pancreatic cancer cells through upregulation of the Snail family members and may serve as an independent predictor for poor outcomes in PDAC patients.

TIP30 loss enhances cytoplasmic and nuclear EGFR signaling and promotes lung adenocarcinogenesis in mice

Lung adenocarcinoma, the most common type of human non-small cell lung cancer (NSCLC), frequently overexpresses EGFR. However, the mechanisms underlying EGFR overexpression are not completely understood. Recent studies have identified that decreased expression of TIP30 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 cells, as well as 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 up-regulated 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.

Targeting insulin-like growth factor I with 10-23 DNAzymes: 2'-O-methyl modifications in the catalytic core enhance mRNA cleavage

Insulin-like growth factor I (IGF-I) and its cognate receptor (IGF-1R) contribute to normal cell function and to tumorigenesis. The role of IGF-I signaling in tumor growth has been demonstrated in vivo using nucleic acid-based strategies. Here, we designed the first 10-23 DNAzymes directed against IGF-I mRNA. Unlike antisense approaches and RNA interference that require protein catalysis, DNAzymes catalyze protein-free RNA cleavage. We identified target sequences and measured catalytic properties of differently designed DNAzymes on short synthetic RNA targets and on in vitro transcribed IGF-I mRNA. The most efficient cleavers were then transfected into cells, and their inhibitory effect was analyzed using reporter gene assays. We found that increasing the size of DNAzyme flanking sequences and modifications of the termini with 2'-O-methyl residues improved cleavage rates of target RNAs. Modification of the catalytic loop with six 2'-O-methyl ribonucleotides at nonessential positions increased or decreased catalytic efficiency depending on the mRNA target site. In cells, DNAzymes with 2'-O-methyl-modified catalytic cores and flanking sequences were able to inhibit reporter gene activity because of specific recognition and cleavage of IGF-I mRNA sequences. Mutant DNAzymes with inactive catalytic cores were unable to block reporter gene expression, demonstrating that the RNA cleaving ability of 10-23 DNAzymes contributed to inhibitory mechanisms. Our results show that nuclease-resistant 2'-O-methyl-modified DNAzymes with high catalytic efficiencies are useful for inhibiting IGF-I gene function in cells.

Tip30 deletion in MMTV-Neu mice leads to enhanced EGFR signaling and development of estrogen receptor-positive and progesterone receptor-negative mammary tumors

Estrogen receptor-positive and progesterone receptor-negative (ER+/PR-) breast cancers account for 15% to 25% of all human breast cancers and display more aggressive malignant characteristics than ER+/PR+ cancers. However, the molecular mechanism underlying development of ER+/PR- breast cancers still remains elusive. We show here that Tip30 deletion dramatically accelerated the onset of mammary tumors in the MMTV-Neu mouse model of breast cancer. The mammary tumors arising in Tip30(-/-)/MMTV-Neu mice were exclusively ER+/PR-. The growth of these ER+/PR- tumors depends not only on estrogen but also on progesterone despite the absence of detectable PR. Tip30 is predominantly expressed in ER+ mammary epithelial cells, and its deletion leads to an increase in the number of phospho-ERα-positive cells in mammary glands and accelerated activation of Akt in MMTV-Neu mice. Moreover, we found that Tip30 regulates the EGFR pathway through controlling endocytic downregulation of EGFR protein level and signaling. Together, these findings suggest a novel mechanism in which loss of Tip30 cooperates with Neu activation to enhance the activation of Akt signaling, leading to the development of ER+/PR- mammary tumors.

CC3/TIP30 regulates metabolic adaptation of tumor cells to glucose limitation

CC3/TIP30 is a metastasis and tumor suppressor, with reduced or absent expression in a variety of aggressive tumors. Overexpression of CC3 in tumor cells predisposes them to apoptosis in response to different death signals. We found that silencing of CC3 expression does not increase apoptotic resistance of cells. However, it strongly improves survival of tumor cells in response to glucose limitation. HeLa cells with silenced CC3 survive long-term in low glucose, and, in comparison to control HeLa cells, show superior metabolic adaptation to glucose limitation. First, unlike the parental HeLa cells, HeLa with silenced CC3 activate and maintain high levels of mitochondrial respiration that is critical for their ability to thrive in low glucose. Second, silencing of CC3 leads to higher expression levels of mitochondrial proteins in respiration complexes when cells are continuously cultured in limiting glucose. Third, HeLa cells with silenced CC3 maintain higher levels of c-MYC and the M2 isoform of pyruvate kinase in low glucose, contributing to more efficient glycolysis. Fourth, HeLa cells with silenced CC3 fail to fully activate AMPK in response to glucose limitation. Inhibition of AMPK, either pharmacologic or via siRNA, protects control HeLa cells from death in low glucose. The metabolic flexibility acquired by cells after silencing of CC3 could be directly relevant to the development of metastatic and aggressive human tumors that frequently have low or absent expression of CC3.

CCN5: biology and pathophysiology

CCN5 is one of six proteins in the CCN family. This family of proteins has been shown to play important roles in many processes, including proliferation, migration, adhesion, extracellular matrix regulation, angiogenesis, tumorigenesis, fibrosis, and implantation. In this review, we focus on the biological and putative pathophysiological roles of CCN5. This intriguing protein is structurally unique among the CCN family members, and has a unique biological activity profile as well.

CCN5: biology and pathophysiology

CCN5 is one of six proteins in the CCN family. This family of proteins has been shown to play important roles in many processes, including proliferation, migration, adhesion, extracellular matrix regulation, angiogenesis, tumorigenesis, fibrosis, and implantation. In this review, we focus on the biological and putative pathophysiological roles of CCN5. This intriguing protein is structurally unique among the CCN family members, and has a unique biological activity profile as well.

CC3/TIP30 affects DNA damage repair

Background

The pro-apoptotic protein CC3/TIP30 has an unusual cellular function as an inhibitor of nucleocytoplasmic transport. This function is likely to be activated under conditions of stress. A number of studies support the notion that CC3 acts as a tumor and metastasis suppressor in various types of cancer. The yeast homolog of CC3 is likely to be involved in responses to DNA damage. Here we examined the potential role of CC3 in regulation of cellular responses to genotoxic stress.

Results

We found that forced expression of CC3 in CC3-negative cells strongly delays the repair of UV-induced DNA damage. Exogenously introduced CC3 negatively affects expression levels of DDB2/XPE and p21CIP1, and inhibits induction of c-FOS after UV exposure. In addition, exogenous CC3 prevents the nuclear accumulation of P21CIP in response to UV. These changes in the levels/localization of relevant proteins resulting from the enforced expression of CC3 are likely to contribute to the observed delay in DNA damage repair. Silencing of CC3 in CC3-positive cells has a modest delaying effect on repair of the UV induced damage, but has a much more significant negative affect on the translesion DNA synthesis after UV exposure. This could be related to the higher expression levels and increased nuclear localization of p21CIP1 in cells where expression of CC3 is silenced. Expression of CC3 also inhibits repair of oxidative DNA damage and leads to a decrease in levels of nucleoredoxin, that could contribute to the reduced viability of CC3 expressing cells after oxidative insult.

Conclusions

Manipulation of the cellular levels of CC3 alters expression levels and/or subcellular localization of proteins that exhibit nucleocytoplasmic shuttling. This results in altered responses to genotoxic stress and adversely affects DNA damage repair by affecting the recruitment of adequate amounts of required proteins to proper cellular compartments. Excess of cellular CC3 has a significant negative effect on DNA repair after UV and oxidant exposure, while silencing of endogenous CC3 slightly delays repair of UV-induced damage.

Decreased TIP30 expression promotes tumor metastasis in lung cancer

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.

Growth hormone and insulin-like growth factor-I in the transition from normal mammary development to preneoplastic mammary lesions

Adult female mammary development starts at puberty and is controlled by tightly regulated cross-talk between a group of hormones and growth factors. Although estrogen is the initial driving force and is joined by luteal phase progesterone, both of these hormones require GH-induced IGF-I in the mammary gland in order to act. The same group of hormones, when experimentally perturbed, can lead to development of hyperplastic lesions and increase the chances, or be precursors, of mammary carcinoma. For example, systemic administration of GH or IGF-I causes mammary hyperplasia, and overproduction of IGF-I in transgenic animals can cause the development of usual or atypical hyperplasias and sometimes carcinoma. Although studies have clearly demonstrated the transforming potential of both GH and IGF-I receptor in cell culture and in animals, debate remains as to whether their main role is actually instructive or permissive in progression to cancer in vivo. Genetic imprinting has been shown to occur in precursor lesions as early as atypical hyperplasia in women. Thus, the concept of progression from normal development to cancer through precursor lesions sensitive to hormones and growth factors discussed above is gaining support in humans as well as in animal models. Indeed, elevation of estrogen receptor, GH, IGF-I, and IGF-I receptor during progression suggests a role for these pathways in this process. New agents targeting the GH/IGF-I axis may provide a novel means to block formation and progression of precursor lesions to overt carcinoma. A novel somatostatin analog has recently been shown to prevent mammary development in rats via targeted IGF-I action inhibition at the mammary gland. Similarly, pegvisomant, a GH antagonist, and other IGF-I antagonists such as IGF binding proteins 1 and 5 also block mammary gland development. It is, therefore, possible that inhibition of IGF-I action, or perhaps GH, in the mammary gland may eventually play a role in breast cancer chemoprevention by preventing actions of both estrogen and progesterone, especially in women at extremely high risk for developing breast cancer such as BRCA gene 1 or 2 mutations.

Methylation of Tip30 promoter is associated with poor prognosis in human hepatocellular carcinoma

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.

TIP30 is associated with progression and metastasis of prostate cancer

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.