Glutathione depletion causes cell growth inhibition and enhanced apoptosisin pancreatic cancer cells

BACKGROUND. Recent studies have demonstrated that Various tumors express en hanced levels of the radical scavenger glutathione (GSH). Moreover, there a re grounds for claiming that GSH plays a crucial role in cell proliferation and tumor resistance. In the current study, we investigated the relation b etween cell growth and GSH Levels in the pancreatic adenocarcinoma cell lin e, AsPC-1, and the significance of GSH in tumor resistance to chemotherapy. METHODS. Cell growth in AsPC-1 was initiated through transforming growth fa ctor-alpha (TGF-alpha) or fetal calf serum (FCS). Then, cell cycle, cell pr oliferation, and cellular GSH content were analyzed at different times in, the presence or absence of buthionine sulfoximine (BSO). The impact of GSH on chemotherapy-induced apoptosis was studied using 5-fluorouracil or melph alan in the presence or absence of BSO. Finally, eve compared the GSH conte nt of 15 pancreatic tumor specimens with 10 normal pancreatic tissue specim ens. RESULTS, Analysis of GSH in pancreatic tissues demonstrated increased GSH l evels in cancerous compared with normal tissue (17.5 +/- 2.3 vs. 8.8 +/- 1. 4 nmol/mg protein; P < 0.004). Incubation of AsPC-1 with TGF-alpha or FCS r esulted in cell proliferation and cell cycle activity, whereas GSH content was not altered. Incubation of GSH-depleted cells with TGF-alpha did not st imulate cell growth. in addition, GSH-depletion resulted in an increased ra te of apoptosis after melphalan (6.3 +/- 0.3% vs. 11.2 +/- 0.3 %; P < 0.001 ), but not after 5-fluorouracil treatment. CONCLUSIONS. Taken together, our results show enhanced GSH levels in pancre atic carcinoma and an essential role of GSH in cell proliferation and in re sistance of AsPC-1 cells. Therefore, GSH-depletion may improve the effectiv ity of adjuvant therapy in pancreatic carcinoma. Cancer 2000;89:1440-7. (C) 2000 American Cancer Society.