HMGCS2 functions as a tumor suppressor and has a prognostic impact in prostate cancer

BackgroundAccumulating studies reported that 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2) may function as either an oncogene or a tumor suppressor in various human cancers. However, its involvement in prostate cancer (PCa) remains unknown. Therefore, the aim of this study was to investigate the clinical significance of HMGCS2 expression and its functions in PCa.MethodsExpression levels of HMGCS2 mRNA and protein were detected by quantitative Polymerase Chain Reaction (qPCR), Western blot and immunohistochemistry, respectively. Associations of HMGCS2 expression with various clinicopathological features and patients' prognosis of PCa were statistically evaluated. Roles of HMGCS2 dysregulation in cell proliferation, invasion and migration of PCa cell lines were also determined.ResultsHMGCS2 protein expression was significantly reduced in PCa tissues compared to adjacent benign prostate tissues at protein levels (P < 0.05). Clinically, low HMGCS2 mRNA expression was dramatically associated with high Gleason score (GS) and pathological grade, as well as the presence of distant metastasis of PCa patients. In addition, PCa patients with low HMGCS2 mRNA expression more frequently had shorter disease-free survival and biochemical recurrence-free survival (all P < 0.05). HMGCS2 expression was identified as an independent factor to predict both disease-free and biochemical recurrence-free survivals of PCa patients. Moreover, loss-of-function experiments demonstrated that HMGCS2 knockdown-expression promotes cell proliferation, colony formation, invasion and migration of PCa cells in vitro and lower the apoptotic rate of PCa cells in vitro.ConclusionsOur data indicate that HMGCS2 may be capable of predicting the risk of biochemical recurrence in PCa patients after radical prostatectomy and functions as a tumor suppressor in PCa cancer, implying its related pathway potential as a drug candidate in anti-PCa therapy.     

胃癌相关抑癌基因甲基化研究进展

DNA甲基化是一种表观遗传修饰,它与肿瘤的发生关系密切。DNA甲基化是基因表达调控的一种方式。抑癌基因启动子高甲基化可以使其表达失活,导致肿瘤发生。胃癌的发生与多基因异常表达密切相关,其中抑癌基因甲基化是胃癌发生发展的重要机制之一。     

Tid1 functions as a tumour suppressor in head and neck squamous cell carcinoma

Human tumourous imaginal disc (Tid1), a human homologue of the Drosophila tumour suppressor protein Tid56, is involved in multiple intracellular signalling pathways such as apoptosis, cell proliferation, and cell survival. Here, we investigated the anti‐tumourigenic activity of Tid1 in head and neck squamous cell carcinoma (HNSCC) in vitro and in vivo. Firstly, the clinical association between Tid1 expression and progression of HNSCC was explored. It was found that expression of Tid1 was negatively associated with tumour status, recurrence, and survival prognosis using immunohistochemical analysis of primary HNSCC patient tumour tissue. Secondly, ectopic expression of Tid1 in HNSCC cells was shown to significantly inhibit cell proliferation, migration, invasion, anchorage‐independent growth, and xenotransplantation tumourigenicity. Thirdly, we showed that overexpression of Tid1 attenuated EGFR activity and blocked the activation of AKT in HNSCC cells, which are known to be involved in the regulation of survival in HNSCC cells. On the other hand, ectopic expression of constitutively active AKT greatly reduced apoptosis induced by Tid1 overexpression. Together, these findings suggest that Tid1 functions as a tumour suppressor in HNSCC tumourigenesis. Copyright © 2009 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Epithelial membrane protein 3 is frequently shown as promoter methylation and functions as a tumor suppressor gene in non-small cell lung cancer

Epithelial membrane protein 3 (EMP3) is a typical member of the epithelial membrane protein (EMP) family which has been reported to be a tumor suppressor gene in neuroblastomas and gliomas and recently reported to be commonly repressed in esophageal squamous cell carcinoma (ESCC) cell lines. However, the expression and clinical significance of EMP3 protein in lung cancer have not yet been elucidated. In this article, we detected that the expression of EMP3 in non-small cell lung cancer was significantly lower than the expression of normal lung tissues (P < 0.01) by western blot. EMP3 expression in Lung cancer was significantly related to p-TNM stage (P < 0.05) and EMP3 was negatively correlated with proliferation marker Ki67(r = − 0.775; P < 0.01), However, no significant correlations were found between EMP3 and other clinical parameters. The post-recurrent survival after radical surgery was poorer in lung cancer patients with lower EMP3 expression (P < 0.01). While in vitro, following release from serum starvation of A549 NSCLC cell, the expression of EMP3 was deregulated. Thus, our finding suggests that EMP3 may be a tumor suppressor gene at the late step of lung cancer, and EMP3 may be a potential prognostic marker and therapeutic target of NSCLC.     

The expression profile of the tumor suppressor gene Lzts1 suggests a role in neuronal development

Background : Neuronal circuit assembly comprises a number of developmental processes that ultimately underlie function. Identifying the molecular events that dictate these processes can give key insights into how neuronal circuit formation is coordinated. To begin to identify such molecular mechanisms, we have analysed the expression of a candidate gene of entirely unknown function within the nervous system. Here we reveal the spatial and temporal distribution of Lzts1 in mouse and chick embryonic spinal cord and propose potential biological functions. Results: Lzts1 mRNA is transiently expressed at the border of the ventricular and mantle zones in subsets of sensory and motor spinal neurons. The protein is localized to the cell body, axon, and trailing process of motor, commissural, and dorsal root neurons during development. Conclusions: Taken together, the spatial and temporal distribution of Lzts1 is consistent with a potential function(s) in cell cycle regulation, axon growth or guidance, and/or migration of neurons. Developmental Dynamics 241:984–994, 2012. © 2012 Wiley Periodicals, Inc.     

miR-23a与转移抑制因子1在结肠癌中的表达及其临床意义

目的 探讨miR-23a( Homo sapiens miR-23a)与转移抑制因子1(metastasis suppressor 1,MTSS1)在结肠癌中的表达情况及其临床意义.方法 运用荧光素报告载体系统检测miR-23a直接调控的靶基因并采用Transwell侵袭实验检测miR-23a对人结肠癌SW620细胞的侵袭能力.收集结肠癌患者手术标本92例,癌旁组织作为正常对照,分别运用原位杂交、免疫组织化学EliVision法检测结肠癌组织及癌旁组织中miR-23a、MTSS1的表达水平,并对二者进行相关性分析.结果 MTSS1是miR-23a直接调控的靶基因,miR-23a下调MTSS1蛋白的表达,增强结肠癌细胞侵袭能力.在92例结肠癌组织中miR-23a阳性表达率为87.0％( 80/92),MTSS1蛋白阳性表达率为17.4％(16/92),分别与癌旁对照组比,差异有统计学意义(P ＜0.01);miR-23a的表达随着结肠癌临床分期演进(P =0.029)和浸润深度增加而增加(P=0.000),且有淋巴结转移的miR-23a的表达显著高于无淋巴结转移组(P=0.041);MTSS1的表达随着结肠癌临床分期演进(P=0.027)和浸润深度增加而下调(P=0.017),且有淋巴结转移的MTSS1的表达显著低于无淋巴结转移组(P=0.009);相关性分析表明,miR-23a表达与MTSS1的表达呈显著负相关(r=-0.594,P=0.013).结论 miR-23a通过靶向抑制MTSS1促进结肠癌SW620细胞生长、侵袭转移;miR-23a的高表达和MTSS1蛋白低表达可能是肠黏膜恶性转变以及结肠癌发生浸润转移的重要生物学标志,检测二者对预测结肠癌浸润转移有重要意义.     

Sex‐specific SNP‐SNP interaction analyses within topologically associated domains reveals ANGPT1 as a novel tumor suppressor gene for lung cancer

Genetic interaction has been recognized to be an important cause of the missing heritability. The topologically associating domain (TAD) is a self‐interacting genomic region, and the DNA sequences within a TAD physically interact with each other more frequently. Sex differences influence cancer susceptibility at the genetic level. Here, we performed both regular and sex‐specific genetic interaction analyses within TAD to identify susceptibility genes for lung cancer in 5204 lung cancer patients and 7389 controls. We found that one SNP pair, rs4262299‐rs1654701, was associated with lung cancer in women after multiple testing corrections (combined P = 8.52 × 10^?9). Single‐SNP analyses did not detect significant association signals for these two SNPs. Both identified SNPs are located in the intron region of ANGPT1. We further found that 5% of nonsmall cell lung cancer patients have an alteration in ANGPT1, indicated the potential role of ANGPT1 in the neoplastic progression in lung cancer. The expression of ANGPT1 was significantly down‐regulated in patients in lung squamous cell carcinoma and lung adenocarcinoma. We checked the interaction effect on the ANGPT1 expression and lung cancer and found that the minor allele “G” of rs1654701 increased ANGPT1 gene expression and decreased lung cancer risk with the increased dosage of “A” of rs4262299, which consistent with the tumor suppressor function of ANGPT1. Survival analyses found that the high expression of ANGPT1 was individually associated with a higher survival probability in lung cancer patients. In summary, our results suggest that ANGPT1 may be a novel tumor suppressor gene for lung cancer.     

MicroRNA-490-5p is a novel tumor suppressor targeting c-FOS in human bladder cancer

Introduction

Recent studies have demonstrated the critical roles of micro-RNAs in tumorigenesis and tumor progression. Here, we describe the regulation and function of miR-490-5p in bladder cancer.

Material and methods

Paired tissue samples were collected from bladder cancer patients (n = 20). Real-time PCR revealed that miR-490-5p expression was significantly down-regulated in human bladder cancer tissues and cells. Also there was an inverse relationship between the expression level of miR-490-5p and the pathological grade of bladder cancer. Western blotting was performed to detect the expression levels of c-FOS and TET1 in 6 matched tumor tissue samples and 4 bladder cell lines. Furthermore, to better understand the underlying mechanisms of miR-490-5p, we conducted gain and loss of function analysis by transfecting bladder cancer T24 cells with chemically synthesized miR-490-5p mimics and inhibitor, respectively.

Results

We found that overexpression of miR-490-5p in T24 cells could inhibit cell proliferation and invasion and induce cell apoptosis. Conversely, suppression of miR-490-5p expression induced cell proliferation and invasion, while it inhibited cell apoptosis. In addition, our bioinformatics prediction and experimental data showed that c-FOS was a potential target of miR-490-5p. The expression level of c-FOS was significantly decreased after miR-490-5p overexpression and significantly increased after miR-490-5p suppression, indicating that c-FOS was a target of miR-490-5p.

Conclusions

These findings suggest that miR-490-5p is a novel tumor suppressor, contributing to the carcinogenesis of bladder cancer by targeting c-FOS.     

肿瘤转移抑制相关基因TMSG-1核仁定位信号序列的鉴定

目的 鉴定肿瘤转移抑制相关基因TMSG-1蛋白中潜在的特异性定位信号序列并探索其亚细胞定位机制.方法 聚合酶链反应(PCR)扩增TMSG-1开放读码框全长及不同长度的截断片段,定向克隆于绿色荧光蛋白(GFP)表达质粒pEGFP-N1;各融合蛋白表达质粒转染人胚肾细胞系HEK293细胞;转染48 h后提取细胞总蛋白进行GFP的Western blot检测或用冷丙酮固定细胞后激光共聚焦显微镜观察融合蛋白的亚细胞定位.结果 GFP分别融合TMSG-1全长蛋白(aa1-380)及其截断片段T1(aa1-70)、T2(aa1-128)、T3(aa129-380)、T4(aa71-128)、T5(aa71-179)和T6(aa71-380),Western blot检测结果显示成功表达了各融合蛋白.激光共聚焦显微镜观察亚细胞定位显示融合蛋白T4(aa71-128)主要定位于细胞核内的核仁部位,融合蛋白T6(aa71-380)以细胞核内弥散分布为主,而TMSG-1全长融合蛋白及融合蛋白T1、T2、T3、T5则定位于胞质.进一步的序列缺失去除T4( aa71-128)羧基末端10个氨基酸得到截断片段T4Δ119-128,T4Δ119-128融合的GFP仍位于细胞核,但核仁内的绿色荧光信号明显减弱.结论 肿瘤转移抑制相关基因TMSG-1存在潜在的核仁定位信号,位于aa119-128(RRRRNQDRPS),这一发现为深入研究TMSG-1的亚细胞定位及相关功能奠定了基础.     

男性乳房发育症组织中PTEN的表达及其意义

目的检测第10号染色体缺失的磷酸酶和张力蛋白同源物基因（phosphatase and tensin homology deleted on chromosome ten, PTEN）在男性乳房发育症中（gynecomastia,GM）的表达及其意义。方法采用SP法免疫组化技术检测68例GM乳腺与24例对照组乳腺标本中PTEN的表达状况。将所选病例按年龄及组织学类型分为3组。结果PTEN在GM与正常男乳中主要表达在导管上皮细胞胞核中。GM中PTEN表达水平较降低（P〈0．01）。PTEN在不同年龄组表达差异有统计学意义（P〈0．05）,且PTEN的表达在中年组、老年组、青年组依次降低;PTEN在不同组织学类型表达差异亦有统计学意义（P〈0．05）,且表达水平在硬化型、过渡型、旺炽型依次降低。结论男性乳房发育症乳腺组织中PTEN蛋白表达的异常可能与男性乳房发育症的发生有关。     

Mutational and expressional analyses of SPOP,a candidate tumor suppressor gene,in prostate,gastric and colorectal cancers

Mounting evidence exists that alterations of ubiquitination processes are involved in cancer pathogenesis. Speckle‐type POZ protein (SPOP) is a key adaptor for Cul3‐based ubiquitination process. Recent studies reported that SPOP may be a tumor suppressor gene (TSG) and somatic mutation of SPOP was detected in prostate cancer (PCA). The aim of this study was to see whether alterations of SPOP protein expression and somatic mutation of SPOP gene are features of cancers. In this study, we analyzed SPOP somatic mutation in 45 gastric (GC), 45 colorectal cancer (CRC) and 45 PCA by single‐strand conformation polymorphism (SSCP). Also, we analyzed SPOP protein expression in 60 GC, 60 CRC and 60 PCA by immunohistochemistry. Overall, we detected three somatic missense mutations of SPOP gene in the coding sequences (p.Ser14Leu, p.Tyr87Cys and p.Phe133Leu). The mutations were observed in two PCA and one CRC. Of note, the p.Phe133Leu was a recurrent mutation reported in an earlier study. In the immunohistochemistry, SPOP protein was expressed in normal gastric, colonic and prostate epithelial cells, whereas it was lost in 30% of GC, 20% of CRC and 37% of PCA. Our data indicate that loss of SPOP expression was common in GC, CRC and PCA, but somatic mutation of SPOP in this study was rare in these tumors. Also, the data provide a possibility that loss of expression of SPOP gene might play a role in cancer pathogenesis by altering TSG functions of SPOP.     

Anticancer activity of the PR domain of tumor suppressor RIZ1

Human tumor suppressor gene RIZ encodes two protein products, tumor suppressor RIZ1 and proto-oncoprotein RIZ2, which regulate cellular functions in a Yin-Yang fashion. The only structural difference between them is that RIZ2 lacks the N-terminal PR domain. In this study, we showed that RIZ1 mRNA expression level was elevated in stage IV of eight different types of cancer (stage III for prostate cancer), indicating that RIZ1 might play an important role in tumor metastasis, and the PR domain alone possessed anticancer activity.     

Alterations in the SMARCB1 (INI1) tumor suppressor gene in familial schwannomatosis

Schwannomatosis is a third major form of neurofibromatosis that has recently been linked to mutations in the SMARCB1 (hSnf5/INI1) tumor suppressor gene. We analyzed the coding region of SMARCB1 by direct sequencing and multiplex ligation-dependent probe amplification (MLPA) in genomic DNA from 19 schwannomatosis kindreds. Microsatellite markers in the SMARCB1 region were developed to determine loss of heterozygosity (LOH) in associated tumors. We detected four alterations in conserved splice acceptor or donor sequences of exons 3, 4 and 6. Two alterations that likely affect splicing were seen in introns 4 and 5. An additional four alterations of unclear pathogenicity were found to segregate on the affected allele in eight families including two non-conservative missense alterations in three families. No constitutional deletions or duplications were detected by MLPA. Nine of 13 tumors examined showed partial LOH of the SMARCB1 region consistent with 'second hits.' Alterations were detected in tumors both with and without somatic NF2 gene changes. These findings support the hypothesis that SMARCB1 is a tumor suppressor for schwannomas in the context of familial disease. Further work is needed to determine its role in other multiple and single tumor syndromes.