EFFECT OF INTERLEUKIN-6 ON THE GROWTH OF HUMAN LUNG-CANCER CELL-LINE

Objective To investigate the effect of interleukin-6 (IL-6) on the gro wth of human lung cancer in vivo as well as in vitro. Methods To exami ne the mRNA level of IL-6 receptor (IL-6R) in high-metastatic human lu ng giant cell carcinoma cell line PG by means of reverse transcription polymerase chain reaction (RT-PCR). To assess the existence of IL-6 r eceptor complex (including IL-6R and gp130) with the treatment of PG c ells by use of recombinant human IL-6 (rhIL-6), recombinant human onco statin M (rhOSM), and recombinant human leukemia inhibitory factor (rh LIF), respectively. To detect the expression of IL-6 by Northern blott ing hybridization and bioactive assay. To identify the effect of IL-6 secreted by PG cells by use of IL-6 and IL-6R antisense oligodeoxynucl eotides (ODNs), and specific neutralizing antibody to IL-6. To documen t the influence of IL-6 on PG cells growth in vivo through the strateg y of the transfection of expression vector inserted antisense IL-6 cDN A.Results RT-PCR analysis revealed that PG cells expressed IL-6R mRNA. Any one of the recombinant cytokine IL-6, OSM and LIF stimulated the growth of PG cells in vitro in a concentration-dependent manner. These results demonstrated IL-6 receptor complex exist in PG cells. At the same time, PG cells expressed IL-6 mRNA and secreted bioactive IL-6. B oth IL-6 antisense ODNs and IL-6R ODNs inhibited PG cells proliferatio n. Treatment of PG cells with IL-6 antibodies reduced the growth of PG cells in vitro. PG cells transfected with IL-6 antisense expression v ector showed a decreased growth in nude mice. Conclusion IL-6 function s as an autocrine growth stimulator for PG cells in vivo as well as in vitro.