title: The anti-apoptotic role of interleukin-6 in human cervical cancer is mediated by up-regulation of Mcl-1 through a PI 3-K/Akt pathway.
abstract: Interleukin-6 (IL-6), a multifunctional cytokine, has recently been implicated in human cervical cancer, though the mechanism remains elusive. This study demonstrates that the anti-apoptotic protein Mcl-1 and IL-6 was concomitantly expressed in human cervical cancer tissues and cell lines, but not in normal cervix tissues. Upon IL-6 treatment, Mcl-1, but not other Bcl-2 family members, was rapidly up-regulated peaking at 4-8 h in human cervical cancer C33A cells. Supporting this observation, using anti-IL-6 or anti-IL-6 receptor antibody to interrupt the IL-6 autocrine loop in SiHa cells significantly reduced cellular level of Mcl-1. This study hypothesizes that the expression of Mcl-1 in cervical cancer cells is regulated by IL-6. The matter of which signaling pathways transduced by IL-6 is responsible for the Mcl-1 up-regulation is further investigated herein. Blocking the STAT3 or MAPK pathway with dominant-negative mutant STAT3F or the MEK inhibitor PD98059 failed to inhibit IL-6-mediated Mcl-1 expression. Meanwhile, the IL-6-induced Mcl-1 up-regulation was effectively abolished by treatment with PI 3-K inhibitors, LY294002. Additionally, overexpression of dominant-negative (dn) Akt in C33A cells could inhibit the IL-6-induced increase of Mcl-1. Finally, overexpression of IL-6 in C33A cells caused a markable resistance to apoptosis induced by doxorubicin or cisplatin. Transient transfection of IL-6-overexpressed cells with a mcl-1 antisense vector, leading to the attenuation of their apoptosis-resistant activity. In conclusion, the data herein suggest that IL-6 regulated the mcl-1 expression via a PI 3-K/Akt-dependent pathway that may facilitate the oncogenesis of human cervical cancer by modulating the apoptosis threshold.
authors.affiliation: Department of Obstetrics and Gynecology, National Taiwan University Hospital, No. 7 Chung-Shan South Road, Taipei, Taiwan.
authors.forename: L H
authors.initials: LH
authors.lastname: Wei
authors.forename: M L
authors.initials: ML
authors.lastname: Kuo
authors.forename: C A
authors.initials: CA
authors.lastname: Chen
authors.forename: C H
authors.initials: CH
authors.lastname: Chou
authors.forename: W F
authors.initials: WF
authors.lastname: Cheng
authors.forename: M C
authors.initials: MC
authors.lastname: Chang
authors.forename: J L
authors.initials: JL
authors.lastname: Su
authors.forename: C Y
authors.initials: CY
authors.lastname: Hsieh
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002294:Carcinoma, Squamous Cell / Q000378:metabolism / Q000503:physiopathology*; D004317:Doxorubicin / Q000494:pharmacology; D005260:Female; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism / Q000502:physiology*; D008164:Luminescent Proteins / Q000378:metabolism; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins / Q000378:metabolism* / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D015398:Signal Transduction; D014162:Transfection; D014407:Tumor Cells, Cultured / Q000187:drug effects; D015854:Up-Regulation; D002583:Uterine Cervical Neoplasms / Q000378:metabolism / Q000503:physiopathology*
chemical_list: D000970:Antineoplastic Agents; D015850:Interleukin-6; D008164:Luminescent Proteins; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D049452:Green Fluorescent Proteins; D004317:Doxorubicin; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt