Suppression of the tumorigenicity of mutant p53-transformed rat embryo fibroblasts through expression of a newly cloned rat nonmuscle myosin heavy chain-B.
In our previous study, a rat homolog of human nonmuscle myosin heavy chain-B (nmMHC-B) was identified by mRNA differential display comparing of transformed against nontransformed Rat 6 cells overexpressing mutant p53val135 gene. The nmMHC-B was found to be expressed in normal Rat 6 embryo fibroblast cell line, but markedly suppressed in the mutant p53val135-transformed Rat 6 cells. To examine the possible involvement of nmMHC-B in cell transformation, we first cloned and sequenced the full length cDNA of rat nmMHC-B, which was then cloned into an ecdysone-expression vector. The resulting construct was introduced into the T2 cell line, a mutant p53val135-transformed Rat 6 cells lacking the expression of the endogenous nmMHC-B. The clonal transfectants, expressing muristerone A-induced nmMHC-B, displayed a slightly flatter morphology and reached to a lower saturation density compared to the parental transformed cells. Reconstitution of actin filamental bundles was also clearly seen in cells overexpressing the nmMHC-B. In soft agar assays, nmMHC-B transfectants formed fewer and substantially smaller colonies than the parental cells in response to muristerone A induction. Moreover, it was strikingly effective in suppressing the tumorigenicity of the T2 cells when tested in nude mice. Thus, the nmMHC-B, known as a component of the cytoskeletal network, may act as a tumor suppressor gene. Our current finding may reveal a novel role of nmMHC-B in regulating cell growth and cell signaling in nonmuscle cells. Oncogene (2001) 20, 58 - 68.
Yam
J W
JW
Department of Biology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
Chan
K W
KW
Hsiao
W L
WL
D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D000970:Antineoplastic Agents / Q000378:metabolism / Q000494:pharmacology; D002448:Cell Adhesion / Q000235:genetics; D002452:Cell Count; D002461:Cell Line, Transformed; D002471:Cell Transformation, Neoplastic / Q000235:genetics* / Q000473:pathology; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000302:isolation & purification; D004622:Embryo, Mammalian; D005347:Fibroblasts / Q000378:metabolism* / Q000473:pathology; D019084:Fluorescent Antibody Technique, Indirect; D015972:Gene Expression Regulation, Neoplastic; D016158:Genes, p53; D005822:Genetic Vectors / Q000096:biosynthesis / Q000138:chemical synthesis; D006131:Growth Inhibitors / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D020409:Molecular Motor Proteins; D008969:Molecular Sequence Data; D009154:Mutation; D018995:Myosin Heavy Chains / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics* / Q000502:physiology; D024501:Nonmuscle Myosin Type IIB; D020033:Protein Isoforms / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D014162:Transfection
D000199:Actins; D000970:Antineoplastic Agents; D018076:DNA, Complementary; D006131:Growth Inhibitors; C103814:MYH9 protein, human; D020409:Molecular Motor Proteins; C491238:Myh9 protein, rat; D020033:Protein Isoforms; D024501:Nonmuscle Myosin Type IIB; C103815:nonmuscle myosin type IIB heavy chain; D018995:Myosin Heavy Chains