Abstract 1605: A possible target key molecule for treatment of pancreatic cancer, screened as cancer-specific immortalization associated gene
Authors: Eguchi Hidetaka , Wada Satoru , Tanimoto Keiji , Hiyama Keiko , Nishiyama Masahiko 
Published: February 2011

Abstract
[Background]
Pancreatic caner shows a poor prognosis, and thus development of an efficient therapy is needed. Last year, we have reported that 13 genes were screened in relation to an event “cancer cell immortalization” by means of comprehensive gene expression analyses of normal, mortal and immortal cells and tissue specimen, and that these might be potent candidates for novel targets of anticancer chemotherapy.
[Purpose]
GTSE1 gene has been selected as one of the 13 genes that expressed at higher levels in immortal cancer cells, though its biological function relative to growth regulation of cancer cells are yet to be determined. To clarify its roles, we performed in vitro experiments to validate its possibility as a target key molecule for treatment of cancer, specifically pancreatic one.
[Materials and Methods]
Quantitative analyses of gene expression levels were conducted by real-time RT-PCR method using gene specific-primers and Universal Probe Library probes (Roche). Whole genome gene expression analysis was conducted with 4×44K Whole Human Genome Microarray (Agilent). Knockdown experiments were performed in various cancer cells using Stealth RNAi and RNAiMax reagent (Invitrogen). Cell proliferation was measured with MTT assay. Caspase activities were analyzed using ApoAlert Caspase Profiling Plate (Clontech). Cell cycle profile was obtained by measuring PI-stained cells with FACS “Calibur” (BD Biosciences).
[Results]
GTSE1 expressed at much higher levels in primary pancreatic and endometrial cancer tissue specimens as compared with matched normal ones: it expressed at higher levels in pancreatic, esophageal, and lung cancer cell lines than normal cells: higher expression levels of GTSE1 were observed in transformants of lung fibroblast TIG-1 cells with SV40 and TERT as compared with TIG-1 cells harboring TERT alone. Treatment with GTSE1 siRNA revealed a significant inhibition of growth of various cancer cells including paclitaxel-resistant ovarian cancer KFr13Tx, cisplatin-resistant lung cancer PC-9/CDDP, and gemcitabine-resistant pancreatic cancer MIAPaCa-2 cells. GTSE1 knockdown induced alteration of cell cycle profile and apoptosis of pancreatic cancer cells: it enhanced caspase 2 and 3 activities. Moreover, to seek for downstream genes, we performed microarray analysis of KLM-1, MIAPaCa-2 and DLD-1 cells treated with GTSE1 siRNA for 72 hrs: We found a gene A that showed less than 1/8 gene expression levels as compared with negative control ones in all of the tested cells by using microarray: This was confirmed by real-time RT-PCR. Furthermore, knockdown of the selected gene also altered cell cycle profile and apoptosis of pancreatic cancer cells.
[Conclusion]
These results indicate that GTSE1 may be involved in cancer-specific immortalization and may be useful as a molecular target for cancer therapy including pancreatic one.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1605.