title: The C-terminal region of Bfl-1 sensitizes non-small cell lung cancer to gemcitabine-induced apoptosis by suppressing NF-κB activity and down-regulating Bfl-1.
abstract: Gemcitabine is used to treat several cancers including lung cancer. However, tumor cells often escape gemcitabine-induced cell death via various mechanisms, which include modulating bcl-2 family members and NF-κB activation. We previously reported that the C-terminal region of Bfl-1 fused with GFP (BC) is sufficient to induce apoptosis in 293T cells. In the present study, we investigated the anti-tumor effect of combined BC gene therapy and gemcitabine chemotherapy in vitro and in vivo using non-small cell lung cancer cell lines and a xenograft model. Cell lines were resistant to low dose gemcitabine (4-40 ng/ml), which induced NF-κB activation and concomitant up-regulation of Bfl-1 (an NF-κB-regulated anti-apoptotic protein). BC induced the apoptosis of A549 and H157 cells with caspase-3 activation. Furthermore, co-treatment with BC and low dose gemcitabine synergistically and efficiently induced mitochondria-mediated apoptosis in these cells. When administered alone or with low dose gemcitabine, BC suppressed NF-κB activity, inhibited the nuclear translocation of p65/relA, and down-regulated Bfl-1 expression. Furthermore, direct suppression of Bfl-1 by RNA interference sensitized cells to gemcitabine-induced cell death, suggesting that Bfl-1 importantly regulates lung cancer cell sensitivity to gemcitabine. BC and gemcitabine co-treatment also showed a strong anti-tumor effect in a nude mouse/A549 xenograft model. These results suggest that lung cancer cells become resistant to gemcitabine via NF-κB activation and the subsequent overexpression of Bfl-1, and that BC, which has both pro-apoptotic and NF-κB inhibitory effects, could be harnessed as a gene therapy to complement gemcitabine chemotherapy in non-small cell lung cancer.
authors.affiliation: Department of Pathology, Cancer Research Institute, Seoul National University College of Medicine, 28 Yeongeon-dong, Jongno-gu, Seoul 110-799, South Korea.
authors.forename: Min-Kyoung
authors.initials: MK
authors.lastname: Kim
authors.forename: Yoon-Kyung
authors.initials: YK
authors.lastname: Jeon
authors.forename: Jong-Kyu
authors.initials: JK
authors.lastname: Woo
authors.forename: Yun
authors.initials: Y
authors.lastname: Choi
authors.forename: Dae-Han
authors.initials: DH
authors.lastname: Choi
authors.forename: Yeul-Hong
authors.initials: YH
authors.lastname: Kim
authors.forename: Chul-Woo
authors.initials: CW
authors.lastname: Kim
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology / Q000627:therapeutic use; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D003841:Deoxycytidine / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D004357:Drug Synergism; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D057809:HEK293 Cells; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D008819:Mice, Nude; D015778:Minor Histocompatibility Antigens; D016328:NF-kappa B / Q000378:metabolism*; D017434:Protein Structure, Tertiary / Q000235:genetics / Q000502:physiology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000008:administration & dosage / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D023041:Xenograft Model Antitumor Assays; D000093542:Gemcitabine
chemical_list: C096816:BCL2-related protein A1; D015778:Minor Histocompatibility Antigens; D016328:NF-kappa B; D019253:Proto-Oncogene Proteins c-bcl-2; D003841:Deoxycytidine; D000093542:Gemcitabine