Microcell-mediated transfer of chromosome 6 into metastatic human C8161 melanoma cells suppresses metastasis but does not inhibit tumorigenicity.
Structural alterations of chromosome 6, including del(6q), are often associated with metastatic melanoma; therefore, we hypothesized that a metastasis-suppressor gene could be coded on human chromosome 6. Highly metastatic C8161 human malignant melanoma cells exhibit chromosomal changes typical of late-stage melanomas. Using microcell-mediated chromosome transfer, a copy of a normal human chromosome 6 was introduced into C8161. Three randomly selected hybrid clones (neo6/C8161.1, neo6/C8161.2 and neo6/C8161.3) were assayed for metastasis in athymic nude mice. All controls - parental C8161 cells, randomly-selected single cell clones, neo-transfected cell clones, neo11/C8161.2 and neo11/C8161.3 - were tumorigenic (270/272 mice) and metastatic (208/272 mice). neo6/C8161 hybrid cells were still tumorigenic (91/93 mice) but were not metastatic (0/195 mice). The presence of the added chromosomes was verified in cultured and tumor cells by amplification of polymorphic (CA)n markers using PCR-RFLP. The neo6/C8161 hybrids display growth and morphological patterns of more differentiated cells than C8161. In Northern blot analysis an inverse relationship between metastatic ability and metastasis-suppressor gene, nm23-H1, expression is observed - with clone neo6/C8161.1 expressing the highest level of nm23 transcripts, neo6/C8161.2 and neo6/C8161.3 expressing intermediate levels, and barely detectable levels are seen in C8161. Collectively, these results suggest that a malignant melanoma metastasis-regulatory gene may be located on human chromosome 6. These results further demonstrate that tumorigenicity and metastatic ability are distinct phenotypes.
Welch
D R
DR
Department of Pathology, Milton S. Hershey Medical Center, Pennsylvania State University College of Medicine, Hershey 17033.
Chen
P
P
Miele
M E
ME
McGary
C T
CT
Bower
J M
JM
Stanbridge
E J
EJ
Weissman
B E
BE
D000818:Animals; D002880:Chromosomes, Human, Pair 11; D002896:Chromosomes, Human, Pair 6; D005260:Female; D016147:Genes, Tumor Suppressor; D006801:Humans; D008545:Melanoma / Q000235:genetics*; D051379:Mice; D009362:Neoplasm Metastasis / Q000235:genetics / Q000517:prevention & control*; D014407:Tumor Cells, Cultured