Abstract 1902: Characterization of choline phospholipid metabolism in pancreatic cancer cells.

Abstract

Abstract Pancreatic cancer has a current 5-year survival rate of less than 3%, accounting for the fourth largest number of cancer deaths in the US. Poor prognosis is, in part, due to its diagnosis at late stages and to limited response to chemotherapy and radiotherapy. Currently, there are no noninvasive markers available for early diagnosis. The development of novel therapeutic strategies is also critically important. 1H magnetic resonance spectroscopy (MRS) is being evaluated in the diagnosis of other solid malignancies such as brain, prostate and breast cancer, and for monitoring therapy in brain cancer. 1H MR spectra of these tumors show elevated total choline (tCho) due to increased phosphocholine (PC). This increase in PC has been attributed to high expression of the choline kinase (Chk)-α gene. Here, for the first time, we have used 1H MRS to characterize choline phospholipid metabolism in a panel of pancreatic adenocarcinomas cell lines. Eight pancreatic adenocarcinoma cell lines and one immortalized pancreatic cell line were used to obtain water soluble cell extracts for high resolution 1H MRS and cell lysates were used for immunoblotting. Human Pancreatic Nestin Expressing (HPNE) cells, stably expressing human telomerase reverse transcriptase (hTERT), hTERT-HPNE cells were used as pancreatic immortalized cells. hTERT-HPNE, Panc-1 and BxPC-3 cells were obtained from ATCC. All other cell lines were obtained from the Johns Hopkins pancreatic xenobank and were derived from pancreatic cancer patients. Panc-1, BxPC-3, Pa09C, Pa28C, Pa20C cell lines were derived from primary adenocarcinomas. While Pa02C and Pa03C were derived from liver metastasis of adenocarcinoma, Pa04C was obtained from lung metastasis of adenocarcinoma. For immunoblots studies, 60 μg whole-cell extracts protein was resolved on SDS-PAGE to detect Chk-α using a custom-made Chk antibody. Water-soluble cell extracts from approximately 1.5x107 cells made using dual-phase extraction were used to acquire proton spectra at a 500 MHz Bruker spectrometer for metabolite quantitation. Immunoblots from various pancreatic cell lines showed different level of Chk-α overexpression with very low expression in Pa04C, Pa28C and undetectable level in hTERT-HPNE cells. Quantitative data for choline containing metabolites obtained from water soluble cell extracts showed elevated PC and tCho in all adenocarcinomas relative to the immortalized pancreatic cells (p<0.05). Differences were also observed within the adenocarcinoma cell lines. While Panc-1, Pa09c and Pa20c showed the highest amounts of PC, Pa20c and Pa03c pancreatic cancer cells showed significantly high free choline compared to all other cell lines (p<0.05). These data support the development of 1H MRS to detect pancreatic cancer and monitor response to treatment. The aberrant choline metabolism observed here in pancreatic cancer cells may also provide novel targets in the treatment of pancreatic cancer. Citation Format: Tariq Shah, Flonne Wildes, Yelena Mironchik, Marie-France Penet, Anirban Maitra, Zaver M. Bhujwalla. Characterization of choline phospholipid metabolism in pancreatic cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1902. doi:10.1158/1538-7445.AM2013-1902