Tumor Suppressor In Lung Cancer 1 Gene Research Articles

Tumor suppressor in lung cancer 1 gene expression in epithelial ovarian cancer.

Loss of Tumor Suppressor in Lung Cancer 1(TSLC1) was observed in many different cancers, but there were only limited research on TSLC1 gene and its roles in cancer suppression in ovarian cancer. This study explores the relationship between TSLC1 gene expression and the ovarian epithelial cancer. Expression levels of TSLC1 were detected by immunohistochemical staining on formal-fixed paraffin embedded pathological specimen. A total of 259 samples were collected, including 24 benign ovarian tumor and 235 malignant ovarian cancers among them. Suppressed expression of TSLC1 protein was observed in 87.8% of poorly differentiated, 85.1% of moderately differentiated, and 46% of well differentiated ovarian epithelial cancers, respectively. There were none suppressed TSLC1 expression in benign ovarian tumor. Kruskal-Wallis test showed a significant association between the expression levels of TSLC1 gene and the degree of ovarian cancer differentiation (P < 0.001). Decreased expression of TSLC1 is associated with the differentiation in ovarian epithelial cancer. TSLC1 might be used as a molecular marker of severity in early stage ovarian cancer, and to help differentiating benign and malignant ovarian tumors.

Significance of TSLC1 gene methylation and TSLC1 protein expression in the progression of cervical lesions

To study the expression and significance of tumor suppressor in lung cancer 1 (TSLC1) gene methylation, the expression of TSLC1 protein in cervix cancer and precancerous lesions as well as their relationship with HR-HPV DNA infection. The clinicopathological data of 92 cases of different cervical lesions during March 2011 to August 2012 treated in our hospital were collected. There were pathologically confirmed 10 cases of normal cervix, 26 cases of cervical intraepithelial neoplasia (CIN) I, 20 cases of CIN II, 15 cases of CIN III, and 21 cases of cervical cancer. Methylation-specific polymerase chain reaction (MSP) was used to detect the TSLC1 gene methylation status in cervical lesions, immunohistochemistry (SP) was used to detect the expressions of TSLC1 protein in cervical lesions, and the second generation hybrid capture (HC2) method was used to detect the high-risk HPV in cervical lesions. The expression rate of TSLC1 gene methylation in normal cervical tissue, CIN I, CIN II, CIN III and SCC were 10.0%, 30.8%, 55.0%, 60.0%, 66.7%, respectively, showing a statistically significant difference (P = 0.004). The positive expression rate of TSLC1 protein in normal cervical tissue, CIN I, CIN II, CIN III and SCC were 100.0%, 80.8%, 65.0%, 33.3%, and 23.8%, respectively, with a significant difference (P = 0.004). In the progression from CIN to invasive cervical cancer, there was no significant correlation between TSLC1 gene methylation and HR-HPV DNA infection (P = 0.919), TSLC1 protein expression and HR-HPV DNA infection (P = 0.664). The correlation analysis showed a negative correlation between TSLC1 gene methylation and TSLC1 protein expression (r = -0.674, P < 0.001). TSLC1 gene promoter methylation may be an early event in the cervical carcinogenesis, become an early sensitive marker, and serve the early prevention and prognostic prediction for cervical cancer.

Reduced tumor suppressor in lung cancer-1 expression is associated with a poor prognosis and its gene promoter methylation in colorectal adenocarcinoma

Objective To investigate the expression of tumor suppressor in lung cancer-1 (TSLC-1) and its gene promoter methylation in colorectal adenocarcinoma,and evaluate its clinical signifi-cance.Methods Immunohistochemical Envision two-step technique was used to detect the expression of TSLC1 in primary colorectal adenocarcinoma; and the relationships between the expression of TSLC1 and clinical parameter including prognosis were analysed statistically.The promoter methylation of TSLC1 gene was detected by methylation-specific polymerase chain reaction.Results TSLC-1 protein expressing positive rate in primary colorectal adenocarcinoma was 41.51％ (22/53),which was obviously lower than that in paraneoplastic colorectal mucous (100％,20/20).Compared with TSLC-1 positive expressing group,group of TSCL-1 negative expressing showed higher lymph node metastasis rate and more advanced clinical stage (P ＜ 0.05).The median survival time in TSLC-1 negative expressing group was 32.22 months,significantly shorter as compared with TSLC-1 positive expressing group (47.55 months) (P ＜ 0.05).TSLC-1 gene promoter region was methylated in 13 of 31 (41.94％) colorectal adenocarcinomas without TSLC-1 protein expressing,that was higher significantly than that in the group of TSLC-1 protein positive expressing (2/22) and normal tissue adjacent to cancer (1/20) (P ＜ 0.05).Conclusion TSLC-1 protein expression was down-regulated in primary colorectal adenocarcinoma,and it was an important factor for predicting prognosis; the methylation-mediated inactivation of TSLC-1 maybe is main mechanism of TSLC-1 expressing down-regulation. Key words: Colorectal adenocarcinama; Tumor suppressor in lung cancer-1; Gene methylation

Tumor suppressor in lung cancer 1 (TSLC1), a novel tumor suppressor gene, is implicated in the regulation of proliferation, invasion, cell cycle, apoptosis, and tumorigenicity in cutaneous squamous cell carcinoma

Tumor suppressor in lung cancer 1 (TSLC1) is tightly implicated in a variety of biological processes and plays critical roles in tumor development and progression. However, the roles of TSLC1 in cutaneous squamous cell carcinoma (CSCC) remain to be unraveled. Here, we reported the TSLC1 gene that was significantly downregulated in CSCC tissues and cells, and survival times of patients with TSLC1 at a low level were markedly lower than that at a high level (P = 0.0070). A stepwise investigation demonstrated that an elevated TSLC1 level evoked obvious proliferation and invasion inhibitions and arrested cell cycle at G0/G1 phase in A431 cells. Moreover, increase of caspase-3 activity mediated by elevated TSLC1 level induced cell apoptosis in A431 cells. Most notably, upregulation of TSLC1 expression reduced the numbers of colony formation and tumorigenicity. Collectively, our results presented herein suggest that TSLC1 as tumor suppressor may play prominent roles in development and progression of CSCC via regulation of different biological processes.

Tumor suppressor in lung cancer-1 (TSLC1) mediated by dual-regulated oncolytic adenovirus exerts specific antitumor actions in a mouse model

The tumor suppressor in lung cancer-1 (TSLC1) is a candidate tumor suppressor of lung cancer, and frequently inactivated in primary non-small cell lung cancer (NSCLC). In this study, we investigated the effects of TSLC1 mediated by a dual-regulated oncolytic adenovirus on lung cancer, and the mechanisms underlying the antitumor actions. The recombinant virus Ad·sp-E1A(Δ24)-TSLC1 was constructed by inserting the TSLC1 gene into the dual-regulated Ad·sp-E1A(Δ24) vector, which contained the survivin promoter and a 24 bp deletion within E1A. The antitumor effects of Ad·sp-E1A(Δ24)-TSLC1 were evaluated in NCI-H460, A549, and H1299 lung cancer cell lines and the normal fibroblast cell line MRC-5, as well as in A549 xenograft model in nude mice. Cell viability was assessed using MTT assay. The expression of TSLC1 and activation of the caspase signaling pathway were detected by Western blot analyses. The tumor tissues from the xenograft models were examined using H&E staining, IHC, TUNEL, and TEM analyses. Infection of A549 lung cancer cells with Ad·sp-E1A(Δ24)-TSLC1 induced high level expression of TSLC1. Furthermore, the Ad·sp-E1A(Δ24)-TSLC1 virus dose-dependently suppressed the viability of NCI-H460, A549, and H1299 lung cancer cells, and did not affect MRC-5 normal fibroblast cells. Infection of NCI-H460, A549, and H1299 lung cancer cells with Ad·sp-E1A(Δ24)-TSLC1 induced apoptosis, and increased activation of caspase-8, caspase-3 and PARP. In A549 xenograft model in nude mice, intratumoral injection of Ad·sp-E1A(Δ24)-TSLC1 significantly suppressed the tumor volume, and increased the survival rate (from less than 15% to 87.5% at d 60). Histological studies showed that injection of Ad·sp-E1A(Δ24)-TSLC1 caused tumor cell apoptosis and virus particle propagation in tumor tissues. The oncolytic adenovirus Ad·sp-E1A(Δ24)-TSLC1 exhibits specific antitumor effects, and is a promising agent for the treatment of lung cancer.

TSLC1 expression discriminates cutaneous melanomas from dysplastic nevi

Cutaneous melanoma is a malignant tumor of melanocytes that causes the majority of skin cancer-related deaths. However, sometimes, discrimination between dysplastic nevi and early melanomas is difficult, even for experienced pathologists. Besides histology, the silencing of tumor suppressor genes aids in the diagnosis of melanoma. We have shown previously that tumor suppressor in lung cancer 1 (TSLC1) is a tumor suppressor gene, and its silencing through aberrant promoter methylation is associated with the generation of cutaneous melanoma. To examine TSLC1 expression in melanocytic skin lesions to determine whether it can serve as a diagnostic marker in histologically questionable lesions. Cytoplasmic localization of the expression of the TSLC1 gene was detected by immunohistochemistry; the levels of TSLC1 mRNA and protein were detected by quantitative real-time reverse transcription-PCR and western blot, respectively. Using immunohistochemistry, the average TSLC1 expression levels in cutaneous melanomas decreased approximately 3.6-fold (n=20) as compared with dysplastic nevi (n=30) and 3.7-fold as compared with normal skin (n=25). The average expression levels of TSLC1 mRNA and protein in dysplastic nevi lesions and normal skin were significantly higher than the levels in cutaneous melanomas. No significant changes in TSLC1 mRNA and protein expressions were found between normal skin and dysplastic nevi. Our results show that a loss of TSLC1 frequently occurs in cutaneous melanoma, and indicate that it could serve as a diagnostic marker for cutaneous melanoma in histologically questionable lesions.

Trichosanthin inhibits DNA methyltransferase and restores methylation-silenced gene expression in human cervical cancer cells

Epigenetic silencing of tumor suppressor genes is a well-established oncogenic process and the reactivation of tumor suppressor genes that have been silenced by promoter methylation is an attractive molecular target for cancer therapy. In this study, we investigated the demethylation activity of trichosanthin (TCS, the main bioactive component isolated from a Chinese medicinal herb) and its possible mechanism of action in cervical cancer cell lines. HeLa human cervical adenocarcinoma and CaSki human cervical squamous carcinoma cells were treated with various concentrations (0, 20, 40 and 80 µg/ml) of TCS for 48 h and the mRNA and protein expression levels of the tumor suppressor genes adenomatous polyposis coli (APC) and tumor suppressor in lung cancer 1 (TSLC1) were detected using reverse transcription (RT)-PCR and western blotting, respectively. We analyzed the methylation status of APC and TSLC1 using methylation-specific PCR (MSP). The expression levels and enzyme activity of DNA methyltransferase 1 (DNMT1) were also examined. The mRNA and protein expression levels of APC and TSLC1 were increased following treatment with various concentrations (0, 20, 40 and 80 µg/ml) of TCS for 48 h. The expression of the APC gene increased 2.55±0.29-, 3.44±0.31- and 4.36±0.14-fold, respectively. The expression of the TSLC1 gene increased 2.28±0.15-, 4.23±0.88- and 6.09±0.23-fold, respectively. MSP detection showed that TCS induced demethylation in HeLa and CaSki cells and that this demethylation activity was accompanied by the decreased expression of DNMT1 and reduced DNMT1 enzyme activity. Our experimental results demonstrate for the first time that TCS is capable of restoring the expression of methylation-silenced tumor suppressor genes and is potentially useful as a demethylation agent for the clinical treatment of human cervical cancer.

Effect of TSLC1 gene on growth and apoptosis in human esophageal carcinoma Eca109 cells

IntroductionTo explore the effect of tumor suppressor in lung cancer 1 (TSLC1) on proliferation and apoptosis in esophageal cancer Eca109 cells.Material and methodsEca109 cells were divided into three groups: TSLC1 transfected group (TTG), mock group (MG) and untransfected group (UTG). The TTG and MG were transfected transiently with the pIRES2-EGFP-TSLC1 eukaryotic expression vector and pIRES2-EGFP vector respectively. The UTG was a blank control. The TSLC1 expression in TTG was analyzed with the fluorogram and RT-PCR method. Cell proliferation was measured with 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium (MTT) assay. Cell cycle was measured by flow cytometry (FCM). Cell apoptosis was detected by Annexin-V/PI double staining FCM.ResultsGreen color was found in TTG and MG. The band of TSLC1 mRNA of TTG was located at about 1400 bp by RT-PCR and agarose gel electrophoresis assay. The TSLC1 inhibited cell proliferation significantly in MTT assay, and the cell proliferation was slower in TTG than MG and UTG. After TSLC1 transfection, cell numbers increased in G0/G1 phase and decreased in S phase. Forty-eight hours after transfection, the apoptosis rate and death rate of TTG were higher than MG and UTG. Thus TSLC1 induced Eca109 cells to apoptosis.ConclusionsThe TSLC1 gene had a potent effect on cell proliferation inhibition, G1/S cell cycle arrest and induction of cell apoptosis in Eca109 cells.

Loss/Down-Regulation of Tumor Suppressor in Lung Cancer 1 Expression Is Associated With Tumor Progression and Is a Biomarker of Poor Prognosis in Ovarian Carcinoma

The tumor suppressor in lung cancer 1 (TSLC1) has been identified as a putative tumor suppressor gene in non-small cell lung cancer. Although loss of TSLC1 has been observed in a number of human malignancies, the expression levels of TSLC1 gene in ovarian cancer and its clinical or prognostic significance have not been investigated. Protein expression levels of TSLC1 was explored by semiquantitative immunohistochemical staining on archival formalin-fixed, paraffin-embedded pathological specimen consisting of 30 normal ovaries, 30 ovarian cystadenomas, 40 borderline ovarian tumors, and 160 invasive ovarian carcinomas. The TSLC1 immunohistochemical staining results were then correlated with various clinicopathologic parameters and patient prognosis using various statistical models. Significantly decreased, or complete loss of, protein expression of the TSLC1 gene was observed in 59% ovarian carcinomas, 45% borderline tumors, and 7% cystadenomas, but in none of the normal ovaries (0%). In ovarian carcinomas, decreased TSLC1 expression was significantly correlated with lymph node metastasis (pN, P = 0.001), distant metastasis (pM, P = 0.028), and more advanced International Federation of Gynecology and Obstetrics stages (P = 0.008). By univariate survival analysis on the ovarian carcinoma cohorts, decreased TSLC1 protein expression was significantly associated with shortened patient survival (mean: 26.9 months in tumors with complete loss of TSLC1 vs 63.1 months in tumors with significantly decreased TSLC1 vs 94.3 months in tumors with normal levels of TSLC1; P < 0.001). By multivariate analysis, TSLC1 protein expression remained as a significant and independent prognostic factor for the prediction of patient survival (P = 0.003). Decreased protein expression of the TSLC1 gene might be important in conferring a more aggressive behavior in ovarian carcinoma. Thus, TSLC1 may be used as an independent prognostic molecular marker for patients with ovarian carcinoma.

TSLC1 gene silencing in cutaneous melanoma

Tumor suppressor in lung cancer 1 (TSLC1) is a tumor suppressor gene that encodes a member of the immunoglobulin superfamily, which is involved in the progression of some types of cancer. Several studies have shown that loss of TSLC1 expression is strongly correlated to methylation of the gene promoter, thus leading to poor prognosis in these cancers. However, the role of TSLC1 in cutaneous melanoma (CM) has not been examined. The purpose of this study was to understand the molecular mechanisms and clinical significance of TSLC1 inactivation in CM. The expression and promoter methylation of TSLC1 were analyzed in 120 CMs. TSLC1 expression was examined by immunohistochemistry, whereas its methylation status was determined by methylation-specific PCR. TSLC1 expression was lost in 84 of 120 (70%) CMs; 36 (30%) CMs were scored as positive for TSLC1 protein expression. The TSLC1 promoter was methylated in 58 (48.33%) of 120 CMs. The incidence of the loss of expression and methylation of TSLC1 significantly increased as the tumor stage advanced (P=0.032 and 0.0021, respectively). Furthermore, in CM, disease-related survival was significantly shorter in patients with tumors losing TSLC1 or harboring methylated TSLC1 (P=0.0003 and 0.0329, respectively). The epigenetic silencing of TSLC1 through methylation is an important event in the pathogenesis of CM, and TSLC1 provides an indicator for poor prognosis.

Involvement of tumor suppressor in lung cancer 1 gene expression in cervical carcinogenesis

Tumor suppressor in lung cancer 1 (TSLC1) is a tumor suppressor gene in non-small cell lung cancer, and loss of TSLC1 gene expression has been observed in a number of epithelial carcinomas and cancer-derived cell lines. We analyzed TSLC1 gene expression by real-time reverse transcription-polymerase chain reaction in 39 invasive cervical carcinomas, 34 cervical intraepithelial neoplasia (CIN) IIIs, 35 CIN IIs, 32 CIN I, 36 inflammation cervical tissues, and 30 normal cervix samples. Loss of TSLC1 gene expression was observed in 30 of 39 (77%) cervical carcinomas, 25 of 34 (73%) CIN IIIs, 9 of 35 (26%) CIN IIs, and 7 of 32 (22%) CIN Is but was not found in inflammation and normal cervix samples. Compared to normal cervical tissue, loss of TSLC1 gene was significantly high in CIN IIIs and cervical cancer (P = 0.00). Moreover, loss of TSLC1 gene expression is observed at a significantly higher frequency in CIN IIIs and cervical cancers than in CIN IIs (P < 0.05). The results show that loss of TSLC1 gene expression is an early event in cervical carcinogenesis and often accompanies invasive cervical cancers.

Loss of TSLC1 expression in lung adenocarcinoma: Relationships with histological subtypes, sex and prognostic significance

The TSLC1 (tumor suppressor in lung cancer 1) gene is a tumor suppressor recently identified through functional complementation in a lung adenocarcinoma cell line A549. In this study we immunohistochemically examined the loss of TSLC1 expression in 93 cases of surgically resected lung adenocarcinoma, and investigated its correlation with clinicopathological parameters, including histological subtypes of tumors. The prognostic significance of loss of TSLC1 expression was analyzed by univariate and multivariate analyses, in parallel with other prognostic markers such as p53, p27, and Ki-67. In non-cancerous lung tissue, TSLC1 was weakly positive in bronchial and bronchiolar epithelial cells, type II pneumocytes and bronchial glands. Overall, TSLC1 was negative in 60 of 93 lung adenocarcinomas. TSLC1 was mainly localized in the cytoplasm of the cells, but cell membrane staining was also observed, especially at sites of cell-cell adhesion. TSLC1-negative tumors were more frequently observed in male cases (41/54 cases, 70.0%) than in female cases (19/39 cases, 48.7%) (P < 0.01). Notably, TSLC1 expression was preserved in a non-invasive, bronchiolo-alveolar histological pattern of tumor cells (P < 0.0001). Survival analyses showed that loss of TSLC1 expression was associated with lower patient survival in univariate and multivariate analyses (P < 0.05 and P = 0.059, respectively). Subset analyses further showed that the prognostic impact of loss of TSLC1 was significant for male patients (P = 0.0089), but not for female patients. We conclude that TSLC1 is expressed in a subset of lung adenocarcinomas, especially in those with bronchiolo-alveolar spread pattern. Loss of TSLC1 is associated with lower patient survival, supporting its role as a tumor suppressor.

TSLC1 gene silencing in cervical cancer cell lines and cervical neoplasia.

Cervical carcinogenesis is initiated by infection with high-risk (i.e., carcinogenic) human papillomavirus (HPV) types. The subsequent progression from premalignant cervical intraepithelial neoplasia (CIN) to invasive cancer is driven by both genetic and epigenetic processes. We assessed the role of the gene encoding the adhesion molecule tumor suppressor in lung cancer 1 (TSLC1) in this progression. We analyzed TSLC1 gene expression by real-time quantitative reverse transcription-polymerase chain reaction, promoter methylation by sodium bisulfite genomic DNA sequencing, and allelic loss by microsatellite analysis in primary keratinocytes, in four non-tumorigenic HPV-immortalized human keratinocyte cell lines, and in 11 human cervical cancer cell lines that were positive for a high-risk HPV DNA type and in normal cervical epithelial cells. We transfected cervical cancer SiHa cells that did not express TSLC1 mRNA with an expression vector containing the TSLC1 complementary DNA (cDNA) or an empty vector and analyzed transfectants for anchorage-independent growth and tumorigenicity in nude mice. We also examined TSLC1 promoter methylation in premalignant cervical lesions and in cervical carcinomas and smears. All statistical tests were two-sided. TSLC1 mRNA was strongly reduced, relative to levels in primary keratinocytes, or absent in 10 (91%) of 11 cervical carcinoma cell lines but in none (0%) of the four HPV-immortalized cell lines (difference = 91%, 95% confidence interval [CI] = 74% to 100%; P =.004). The TSLC1 promoter was hypermethylated, relative to normal foreskin and cervical epithelial cells, in nine (82%) of the 11 cervical carcinoma cell lines but in none (0%) of the four HPV-immortalized cell lines (difference = 82%, 95 CI = 59% to 100%; P =.01). Seven (88%, 95% CI = 47% to 100%) of the eight SiHa/TSLC1 transfectants displayed a marked reduction in anchorage-independent growth (i.e., 0-100 colonies per 5000 cells) compared with none of the four (0%, 95% CI = 0% to 60%) SiHa transfectants bearing the empty vector (i.e., SiHa/hygro transfectants; difference = 88%, 95% CI = 65% to 100%; P =.01) or untransfected SiHa cells. All seven mice (100%, 95% CI = 59% to 100%) injected with untransfected SiHa cells or SiHa/hygro transfectants displayed tumors of at least 50 mm(3) by 2-6 weeks after injection compared with none of eight mice (0%, 95% CI = 0% to 37%) injected with the SiHa/TSLC1 transfectants (difference = 100%, 95% CI = 68% to 100%; P<.001). We detected TSLC1 promoter hypermethylation in seven (35%, 95% CI = 15% to 59%) of 20 high-grade CIN lesions (i.e., CIN II and III) and in 30 (58%, 95% CI = 43% to 71%) of 52 cervical squamous cell carcinomas compared with none (0%, 95% CI = 0% to 34%) of nine normal cervical epithelial biopsy samples and none (0%, 95% CI = 0% to 22%) of 12 CIN I lesions (P<.001 for cervical squamous cell cancer versus normal epithelial biopsy samples plus CIN I lesions). TSLC1 gene silencing via promoter hypermethylation is a frequent event in the progression from high-risk HPV-containing, high-grade CIN lesions to invasive cervical cancer.

Clinical implication and prognostic significance of the tumor suppressor TSLC1 gene detected in adenocarcinoma of the lung.

Recently, the TSLC1 (tumor suppressor in lung cancer 1) gene has been identified as a novel tumor suppressor in human nonsmall cell lung carcinoma. To the authors' knowledge, the clinical relevance of TSLC1 gene expression has not been studied using patient data and surgical samples. The current study was designed to evaluate whether the TSLC1 gene can serve as a target for the prognostic determination of patients with pulmonary adenocarcinoma. A total of 38 patients who were surgically treated for proven primary lung adenocarcinoma were enrolled in the current study. Surgical specimens were examined for TSLC1 protein expression immunohistochemically and by Western blot analysis. The correlation between levels of TSLC1 expression and pathologic characteristics, as well as prognosis, was investigated. All patients underwent a potentially curative resection of their tumor. TSLC1 antigen expression as evaluated by immunohistochemistry was confirmed by immunoblotting. The expression of TSLC1 protein was found to be inversely correlated with advanced disease stage, lymph node involvement, lymphatic permeation, and vascular invasion. The 4-year overall survival rates of patients with a tumor demonstrating high (> 70% positive cells [n = 14 patients]), intermediate (20-70% positive cells [n = 10 patients]), and low (< 20% positive cells [n = 14 patients]) expression of the TSLC1 antigen were 84%, 28%, and 7%, respectively. In addition, the disease-free survival of patients with a tumor that demonstrated a high percentage of TSLC1 protein-positive cells was reported to be significantly better than that of patients with a tumor that showed a low percentage of TSLC1 protein-positive cells. The loss or reduction of TSLC1 expression in resected lung adenocarcinoma cases was associated with a poor prognosis, indicating that TSLC1 represents a central effector gene for controlling the biologic aggressiveness of the tumor and that it is an essential biomarker for predicting patient prognosis. These data may help to detect those patients at high risk for recurrence who might benefit from additional therapeutic strategies such as adjuvant therapy.

Role of the Tumor-suppressor TSLC1 (Tumor Suppressor in Lung Cancer 1) Gene as a Prognostic Factor in Lung Adenocarcinom

PURPOSE: Recently, TSLC1 (tumor suppressor in lung cancer 1) gene has been identified as a novel tumor suppressor in human non-small cell lung cancers. The clinical relevance of TSLC1 gene expression has never been studied using patients’ data and surgical samples. The present study was designed to evaluate whether the TSLC1 gene can be serve a target for a prognostic determinant of patients with pulmonary adenocarcinomas.

Hypermethylation of the TSLC1 gene promoter in primary gastric cancers and gastric cancer cell lines.

The TSLC1 (tumor suppressor in lung cancer–1) gene is a novel tumor suppressor gene on chromosomal region 11q23.2, and is frequently inactivated by concordant promoter hypermethylation and loss of heterozygosity (LOH) in non‐small cell lung cancer (NSCLC). Because LOH on 11q has also been observed frequently in other human neoplasms including gastric cancer, we investigated the promoter methylation status of TSLC1 in 10 gastric cancer cell lines and 97 primary gastric cancers, as well as the corresponding non‐cancerous gastric tissues, by bisulfite‐SSCP analysis followed by direct sequencing. Allelic status of the TSLC1 gene was also investigated in these cell lines and primary gastric cancers. The TSLC1 promoter was methylated in two gastric cancer cell lines, KATO‐III and ECC10, and in 15 out of 97 (16%) primary gastric cancers. It was not methylated in non‐cancerous gastric tissues, suggesting that this hypermethylation is a cancer‐specific alteration. KATO‐III and ECC10 cells retained two alleles of TSLC1, both of which showed hypermethylation, associated with complete loss of gene expression. Most of the primary gastric cancers with promoter methylation also retained heterozygosity at the TSLC1 locus on 11q23.2. These data indicate that bi‐allelic hypermethylation of the TSLC1 promoter and resulting gene silencing occur in a subset of primary gastric cancers.