TY - JOUR
T1 - Interleukin-6 dependent induction of the cyclin dependent kinase inhibitor p21(WAF1/CIP1) is lost during progression of human malignant melanoma
AU - Flørenes, Vivi Ann
AU - Lu, Chao
AU - Bhattacharya, Nandita
AU - Rak, Janusz
AU - Sheehan, Capucine
AU - Slingerland, Joyce M.
AU - Kerbel, Robert S.
N1 - Funding Information:
We thank those who kindly provided antibodies for these studies and Meenhard Herlyn for the WM panel of human melanoma cell lines. YE Chin is gratefully acknowledged for helpful discussion regarding the DNA band shift assay. We are grateful to Cassandra Cheng, Mina Viscardi and Lynda Woodcock for their excellent secretarial assistance. VAF is supported by a postdoctoral fellowship from the Medical Research Council of Canada and by stipends from the Norwegian Research Council and Lillemor Grobstocks legacy. This work was supported by a grant from the National Institutes of Health USA, CA 41223 to RSK and the National Cancer Institute of Canada to JMS. RSK is a Terry Fox Research Scientist of the National Cancer Institute of Canada. JMS is supported by Cancer Care Ontario.
PY - 1999/1/28
Y1 - 1999/1/28
N2 - Human melanoma cell lines derived from early stage primary tumors are particularly sensitive to growth arrest induced by interleukin-6 (IL-6). This response is lost in cell lines derived from advanced lesions, a phenomenon which may contribute to tumor aggressiveness. We sought to determine whether resistance to growth inhibition by IL-6 can be explained by oncogenic alterations in cell cycle regulators or relevant components of intracellular signaling. Our results show that IL-6 treatment of early stage melanoma cell lines caused G1 arrest, which could not be explained by changes in levels of G1 cyclins (D1, E), cdks (cdk4, cdk2) or by loss of cyclin/cdk complex formation. Instead, IL-6 caused a marked induction of the cdk inhibitor p21(WAF1/CIP1) in three different IL-6 sensitive cell lines, two of which also shelved a marked accumulation of the cdk inhibitor p27(Kip1). In contrast, IL-6 failed to induce p21(WAF1/CIP1) transcript and did not increase p21WAF1/CIP1 or p27(Kip1) proteins in any of the resistant lines. In fact, of five IL-6 resistant cell lines, only two expressed detectable levels of p21(WAF1/CIP1) mRNA and protein, while in three other lines, p21(WAF1/CIP1) was undetectable. IL-6 dependent upregulation of p21(WAF1/CIP1) was associated with binding of both STAT3 and STAT1 to the p21(WAF1/CIP1) promoter. Surprisingly, however, IL-6 stimulated STAT binding to this promoter in both sensitive and resistant cell lines (with one exception), suggesting that gross deregulation of this event is not the unifying cause of the defect in p21(WAF1/CIP1) induction in IL-6 resistant cells. In somatic cell hybrids of IL-6 sensitive and resistant cell lines, the resistant phenotype was dominant and IL-6 failed to induce p21(WAF1/CIP1). Thus, our results suggest that in early stage human melanoma cells, IL-6 induced growth inhibition involves induction of p21(WAF1/CIP1) which is lost in the course of tumor progression presumably as a result of a dominant oncogenic event.
AB - Human melanoma cell lines derived from early stage primary tumors are particularly sensitive to growth arrest induced by interleukin-6 (IL-6). This response is lost in cell lines derived from advanced lesions, a phenomenon which may contribute to tumor aggressiveness. We sought to determine whether resistance to growth inhibition by IL-6 can be explained by oncogenic alterations in cell cycle regulators or relevant components of intracellular signaling. Our results show that IL-6 treatment of early stage melanoma cell lines caused G1 arrest, which could not be explained by changes in levels of G1 cyclins (D1, E), cdks (cdk4, cdk2) or by loss of cyclin/cdk complex formation. Instead, IL-6 caused a marked induction of the cdk inhibitor p21(WAF1/CIP1) in three different IL-6 sensitive cell lines, two of which also shelved a marked accumulation of the cdk inhibitor p27(Kip1). In contrast, IL-6 failed to induce p21(WAF1/CIP1) transcript and did not increase p21WAF1/CIP1 or p27(Kip1) proteins in any of the resistant lines. In fact, of five IL-6 resistant cell lines, only two expressed detectable levels of p21(WAF1/CIP1) mRNA and protein, while in three other lines, p21(WAF1/CIP1) was undetectable. IL-6 dependent upregulation of p21(WAF1/CIP1) was associated with binding of both STAT3 and STAT1 to the p21(WAF1/CIP1) promoter. Surprisingly, however, IL-6 stimulated STAT binding to this promoter in both sensitive and resistant cell lines (with one exception), suggesting that gross deregulation of this event is not the unifying cause of the defect in p21(WAF1/CIP1) induction in IL-6 resistant cells. In somatic cell hybrids of IL-6 sensitive and resistant cell lines, the resistant phenotype was dominant and IL-6 failed to induce p21(WAF1/CIP1). Thus, our results suggest that in early stage human melanoma cells, IL-6 induced growth inhibition involves induction of p21(WAF1/CIP1) which is lost in the course of tumor progression presumably as a result of a dominant oncogenic event.
KW - Melanoma, IL-6
KW - p21(WAF1/CIP1)
KW - p27(Kip1)
KW - Sensitivity
KW - STAT
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UR - http://www.scopus.com/inward/citedby.url?scp=0033611585&partnerID=8YFLogxK
U2 - 10.1038/sj.onc.1202382
DO - 10.1038/sj.onc.1202382
M3 - Article
C2 - 10023678
AN - SCOPUS:0033611585
VL - 18
SP - 1023
EP - 1032
JO - Oncogene
JF - Oncogene
SN - 0950-9232
IS - 4
ER -
