Therapeutic Target For Esophageal Squamous Cell Carcinoma Research Articles

Phosphorylated mTOR Expression is Associated with Poor Prognosis for Patients with Esophageal Squamous Cell Carcinoma

The mammalian target of rapamycin (mTOR) plays central roles in the regulation of cell growth and proliferation by monitoring nutrient availability, cellular energy level, oxygen level, and mitogenic signals. The aberrant activation of mTOR in relation to clinical outcome has been reported in several types of cancers. mTOR is increasingly important as a potential target for anticancer therapy. Nonetheless, a prognostic feature of mTOR activation in esophageal squamous cell carcinoma (ESCC) remains uncertain. First, in order to validate phospho-specific mTOR antibody (Ser2448), phosphorylated mTOR (p-mTOR) expression levels in five ESCC cell lines under cultural conditions with or without everolimus (mTOR inhibitor, also known as RAD001) were evaluated by in vitro immunohistochemistry and immunoblotting. Second, we examined p-mTOR expression by immunohistochemistry using 143 resected ESCC specimens. Prognostic significance of p-mTOR expression was examined by Cox regression and Kaplan-Meier analyses. Among 143 patients, 71 (49.7%) were classified into p-mTOR-positive and 72 (50.3%) were classified into p-mTOR-negative. Compared with p-mTOR-negative patients, p-mTOR-positive patients experienced high overall mortality [hazard ratio (HR) 2.44; 95% confidence interval (CI), 1.24-4.83; P = 0.008], which persisted in multivariate analysis (multivariate HR 2.92; 95% CI, 1.48-5.78; P = 0.002). A similar finding was observed for esophageal cancer-specific mortality. p-mTOR expression was not related with any clinical or pathologic variables including age, sex, tumor location, histological grading, operative procedure, T classification (tumor invasion), or lymph-node metastasis. p-mTOR overexpression was independently associated with poor prognosis in ESCC, supporting the potential for mTOR as a therapeutic target for ESCC.

Serial analysis of gene expression of esophageal squamous cell carcinoma: ADAMTS16 is upregulated in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most common malignancies worldwide. To identify potential diagnostic markers for ESCC and therapeutic targets for ESCC, we used Serial Analysis of Gene Expression (SAGE) on one ESCC sample. We obtained a total of 14,430 tags, including 5765 that were unique. By comparing SAGE tags from the ESCC sample with those from normal human squamous esophagus, we found several genes that were differentially expressed between ESCC and normal squamous esophagus. Among these, we focused on the ADAM metallopeptidase with thrombospondin type 1 motif, 16 (ADAMTS16) gene because quantitative RT-PCR analysis showed a high level of ADAMTS16 expression in eight out of 20 ESCC samples (40%), but not in 15 kinds of normal tissues. Western blot analysis also showed upregulation of ADAMTS16 protein in ESCC tissues. Furthermore, ADAMTS16 protein was detected in culture media from the TE5 esophageal cancer cell line. Knockdown of ADAMTS16 in TE5 cells inhibited both cell growth and invasion ability. Our present SAGE data provide a list of genes potentially associated with ESCC. ADAMTS16 could be a novel diagnostic and therapeutic target for ESCC.

Overexpression of SMYD2 relates to tumor cell proliferation and malignant outcome of esophageal squamous cell carcinoma

Although we have identified two putative targets, ATF3 and CENPF, for a frequently gained/amplified region around 1q32-q41 in esophageal squamous cell carcinoma (ESCC), it is possible that other amplification targets remain to be identified. In this study, we tested whether SET and MYND domain-containing protein 2 (SMYD2), located between those two genes and encoding a lysine methyltransferase for histone H3K36 and p53K370 that regulates transcription and inhibits transactivation activity, respectively, acts as a cancer-promoting gene through activation/overexpression in ESCC. Frequent overexpression of SMYD2 messenger RNA and protein was observed in KYSE150 cells with remarkable amplification at 1q32-41.1 and other ESCC cell lines (11/43 lines, 25.6%). Overexpression of SMYD2 protein was frequently detected in primary tumor samples of ESCC (117/153 cases, 76.5%) as well and significantly correlated with gender, venous invasion, the pT category in the tumor-lymph node-metastases classification and status of recurrence. Patients with SMYD2-overexpressing tumors had a worse overall rate of survival than those with non-expressing tumors, and SMYD2 positivity was independently associated with a worse outcome in the multivariate analysis. Knockdown of SMYD2 expression inhibited and ectopic overexpression of SMYD2 promoted the proliferation of ESCC cells in a TP53 mutation-independent but SMYD2 expression-dependent manner. These findings suggest that SMYD2 plays an important role in tumor cell proliferation through its activation/overexpression and highlight its usefulness as a prognosticator and potential therapeutic target in ESCC.

Pituitary Tumor-Transforming 1 Increases Cell Motility and Promotes Lymph Node Metastasis in Esophageal Squamous Cell Carcinoma

Human pituitary tumor-transforming 1 (PTTG1)/securin is a putative oncoprotein that is overexpressed in various tumor types. However, the involvement of PTTG1 in gastrointestinal cancer development and progression remains unclear. In this study, we investigated the clinical significance and biological effects of PTTG1 in esophageal squamous cell carcinoma (ESCC). Immunohistochemical studies performed on 113 primary ESCC specimens revealed a high prevalence of PTTG1 overexpression (60.2%), which was significantly associated with lymph node metastasis (regional, P = 0.042; distant, P = 0.005), advanced tumor stage (P = 0.028), and poorer overall survival (P = 0.017, log-rank test; P = 0.044, Cox proportional hazard model). Eleven ESCC cell lines expressed PTTG1 protein at levels 2.4 to 6.6 times higher than those in normal esophageal epithelial cells (HEEpiC). PTTG1 protein expression was confined to the nucleus in HEEpiC cells but present in both the cytoplasm and nucleus in ESCC cells. Two small interfering RNAs (siRNA) inhibited PTTG1 mRNA and protein expression in three ESCC cell lines by 77% to 97%. In addition, PTTG1 down-regulation by these siRNAs significantly reduced cell motility in all three ESCC cell lines (P < 0.01) in vitro, as well as popliteal lymph node metastases of ESCC cells in nude mice (P = 0.020). Global gene expression profiling suggested that several members of the Ras and Rho gene families, including RRAS, RHOG, ARHGAP1, and ARHGADIA, represented potential downstream genes in the PTTG1 pathway. Taken together, these findings suggest that PTTG1 overexpression promotes cell motility and lymph node metastasis in ESCC patients, leading to poorer survival. Thus, PTTG1 constitutes a potential biomarker and therapeutic target in ESCCs with lymph node metastases.