Crosstalk between autophagy and apoptosis in the regulation of paclitaxel-induced cell death in v-Ha-ras-transformed fibroblasts.
The previous studies by this author group has shown that paclitaxel, a mitotic inhibitor used in breast cancer chemotherapy, inhibits cell growth via induction of Raf-1-dependent apoptosis. In this article, the role of autophagy in paclitaxel anticancer action was investigated using v-Ha-ras-transformed NIH 3T3 cells. Paclitaxel induced a notable increase in the number of fluorescent particles labeled with monodansylcadaverine (MDC), a specific marker for autophagic vacuoles. MDC-labeled vacuoles clearly exhibited the fluorescent-tagged LC3 in cells transiently overexpressing GFP-LC3 (a protein that associates with autophagosome membranes). However, autophagy inhibition with 3-methyladenine (3-MA) failed to rescue v-Ha-ras-transformed NIH 3T3 cells from paclitaxel-induced cell death. More interestingly, the apoptosis inhibition by overexpression of the X-linked inhibitor of apoptosis (XIAP) did not fully block the cell death by paclitaxel, implying that apoptosis inhibition might accelerate the autophagic components of the paclitaxel response. Conversely, Raf-1 shRNA expression protected against paclitaxel-induced cell death through the simultaneous inhibition of both autophagy and apoptosis. These results suggest that both autophagy and apoptosis act as cooperative partners to induce cell death in v-Ha-ras-transformed NIH 3T3 cells treated with paclitaxel.
Division of Life Sciences, College of Natural Sciences, University of Incheon, Yeonsu-gu, Incheon, Republic of Korea.
Ki-Hwan
KH
Eum
Michael
M
Lee
D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D050256:Antimitotic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001343:Autophagy / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D002461:Cell Line, Transformed; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D011905:Genes, ras; D051379:Mice; D008856:Microscopy, Fluorescence; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D041681:NIH 3T3 Cells; D017239:Paclitaxel / Q000494:pharmacology*; D019908:Proto-Oncogene Proteins c-raf / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection; D051636:X-Linked Inhibitor of Apoptosis Protein / Q000235:genetics / Q000378:metabolism
D050256:Antimitotic Agents; D008869:Microtubule-Associated Proteins; D011993:Recombinant Fusion Proteins; D051636:X-Linked Inhibitor of Apoptosis Protein; C025946:3-methyladenine; D019908:Proto-Oncogene Proteins c-raf; C505409:Casp3 protein, mouse; D053148:Caspase 3; D000225:Adenine; D017239:Paclitaxel