Association Of Survivin Splicing Variants' Expression With And Clinical Parameter, Prognosis, Proliferation, Apoptosis, And Chemoresistance In Gastric Cancer

Objective: We have aimed to study the expression of three survivin splicing variants in gastric cancer and to evaluate the significant correlation between survivin variants' expression and clinical parameter, prognosis, proliferation, apoptosis, and chemoresistance in gastric cancer.Methods: This study was divided into three parts. Part one: Real time quantitative RT-PCR was applied to analyze expression of survivin variants in 7 cell lines and 77 paired tumors as well as normal gastric mucosa samples at the mRNA level. The correlation between survivin variants' expression and clinical parameter or prognosis was also tested by statistic analysis. Part Two: Preliferative and apoptotic activity was measured by Ki-67 immunohistochemical analysis ( LSAB ) and terminal deoxynucleotidyl-transferase- mediated dUTP-biotin nick end labeling (TUNED method, respectively. The correlation between survivin variants' expression and proliferation or apoptosis was tested by statistic analysis. Part Three: Theclinical resistance of anticancer agents (CDDP, MMC, 5-FU, TXT, and GEM) was analyzed by histocultrure drug-response assay (HDRA). The correlation between survivin variants' expression and chemoresistance was tested by statistic analysis.Results: All of the survivin variants were detected in 7 cancer cell lines. Among the 77 tumor samples, survivin expression was detected in all tumor samples (77/77), which was not only the dominant transcript but also a poor prognostic biomarker(P=0.003); 79.2% (61/77) of the samples demonstrated survivin-2B expression, which was associated with tumor stage(P=0.001), histological type(P=0.007), and depth of tumor invision(P=0.031); 64.9% (50/77) of samples had survivin-AEx3 expression, which showed a significant reverse association with apoptosis index(P=0.019). Among the 45 (58.4%) of the normal mucosa samples, in contrast, survivin expression was detectable and 22 (28%) mucosa samples had survivin2B expression and 11 (14.3%) demonstrated survivin-AEx3 expression. Among the 39 tumor samples, in vitro efficacy rates of CDDP, MMC, 5FU, TXT, and GEM in HDRA were 36.8%, 31.2%, 23.1%, 20.5%, and 12.5%, respectively, which were equivalent to previous HDRA studies and historical clinical studies in gastric cancer patients. Importantly, the mRNA levels of wild-type survivin were revealed in significant statistical differences (p=0.021) between the chemoresistanct and no-resistant {Taxotere l[docetaxel (TXT) ]} groups.Conclusion: 1. Three survivin splicing variants were remarkably upregulated in gastric cancers compared with those in normal tissues. The results suggested that the significant participation of three survivin splicing variants may be involved in gastric cancer development. In addition, wild-type survivin were detected in all gastric cancer samples in a significant high level, whichcontribute to early diagnosis of gastric cancer.2. Elevated expression level of wild-type survivin promoted not only docetaxel-resistance but also bad prognosis in patients with gastric cancer.3. Survivin-2B expression level, hypothesized to be natural occurring antagonist of survivin or survivin-AEx3, was correlated with the tumor stage, tumor differentiation, and tumor invasion.4. We also demonstrated a significant negative correlation between the expression level of survivin-AEx3 and the apoptotic index for the first time, which may play a more crucial role in the regulation of apoptosis.