Increased expression of protein kinase C alpha plays a key role in retinoic acid-induced melanoma differentiation

Differentiation of B16 mouse melanoma cells induced by retinoic acid (RA) is preceded by a large increase in protein kinase C alpha (PKC alpha) mRNA and protein. To determine the role of PKC alpha in the differentiation program, we stably transfected B16-F1 cells with a plasmid containing the full l...

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Bibliographic Details
Published in:The Journal of biological chemistry 1992-07, Vol.267 (19), p.13356-13360
Main Authors: GRUBER, J. R, OHNO, S, NILES, R. M
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
Blotting, Southern
Blotting, Western
Cell Differentiation - drug effects
Cell differentiation, maturation, development, hematopoiesis
Cell physiology
DNA - genetics
Fundamental and applied biological sciences. Psychology
Male
Melanins - metabolism
Melanoma, Experimental - enzymology
Melanoma, Experimental - pathology
Mice
Mice, Inbred C57BL
Molecular and cellular biology
Plasmids
Protein Kinase C - genetics
Protein Kinase C - metabolism
RNA, Messenger - metabolism
Tretinoin - pharmacology
Tumor Cells, Cultured
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Summary:Differentiation of B16 mouse melanoma cells induced by retinoic acid (RA) is preceded by a large increase in protein kinase C alpha (PKC alpha) mRNA and protein. To determine the role of PKC alpha in the differentiation program, we stably transfected B16-F1 cells with a plasmid containing the full length PKC alpha cDNA driven by an SV40 promoter. Two out of thirty-two colonies screened were determined to overexpress PKC by 2-4-fold according to Western blot analysis and PKC enzyme activity. When compared to control cells (wild-type cells and cells transfected only with the neomycin resistance gene), PKC alpha overexpressing clones displayed longer doubling times, diminished anchorage-independent growth, and increased melanin production. RA treatment of control cells mimicked these phenotypic characteristics. When injected subcutaneously into syngeneic mice, PKC alpha overexpressing clones produced smaller tumors and had longer latencies than control cells. These findings, combined with the fact that phorbol esters down-regulate PKC and antagonize RA action suggest that PKC alpha plays a key role in the RA-induced melanoma differentiation.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(18)42218-1