Interleukin-6 acts as an antiapoptotic factor in human esophageal carcinoma cells through the activation of both STAT3 and mitogen-activated protein kinase pathways.
The production of interleukin-6 (IL-6) has been discovered in a variety of human tumors. Here we report the expression of IL-6, IL-6 receptor alpha (IL-6Ralpha), and gp130 in human esophageal carcinoma tissues. We further demonstrate that IL-6 protects an esophageal carcinoma cell line CE48T/VGH from apoptosis induced by staurosporine. IL-6 stimulation induced a rapid phosphorylation of gp130 and STAT3, and a dominant-negative STAT3 completely abolished the antiapoptotic effect. IL-6 also activated ERK 1/2 in CE48T/VGH cells. Inhibition of the ERK activation by PD98059 and transfection of a dominant-negative ERK2 completely blocked the protection of IL-6 against apoptosis. Thus, both STAT and MAP kinase pathways are responsible for the IL-6-delivered survival signal in human esophageal carcinoma cells. In contrast, PI3-K inhibitors only partially attenuated the effect of IL-6, suggesting that PI3-K does not play a major role in the antiapoptotic signal of IL-6 in our system. To investigate whether IL-6 could induce the production of antiapoptotic molecules, proteins of the Bcl-2 family were measured. While Bcl-2, Bcl-x(L,), and Bax were not affected, Mcl-1 was induced by IL-6 in human esophageal carcinoma cells. Our results suggest that IL-6 may contribute to the progression of esophageal cancers in an autocrine or paracrine manner.
Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei, Taiwan, Republic of China.
Chuen-Miin
CM
Leu
Fen-Hwa
FH
Wong
Chungming
C
Chang
Shiu-Feng
SF
Huang
Cheng-po
CP
Hu
D017209:Apoptosis; D002455:Cell Division; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000502:physiology*; D004938:Esophageal Neoplasms / Q000473:pathology*; D006801:Humans; D015850:Interleukin-6 / Q000032:analysis / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology*; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins / Q000096:biosynthesis; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D019253:Proto-Oncogene Proteins c-bcl-2; D019947:Receptors, Interleukin-6 / Q000032:analysis; D050796:STAT3 Transcription Factor; D015398:Signal Transduction; D015534:Trans-Activators / Q000502:physiology*
D004268:DNA-Binding Proteins; D015850:Interleukin-6; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D019947:Receptors, Interleukin-6; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D015534:Trans-Activators; D019869:Phosphatidylinositol 3-Kinases; D020928:Mitogen-Activated Protein Kinases