Altered levels of endogenous retrovirus-like sequence (VL30) RNA during mouse epidermal cell carcinogenesis.
Gene expression during mouse keratinocyte carcinogenesis was examined in a clonal cell model. Tumor cells from three separate initiated cell lineages were compared with their nontumorigenic precursors and with the progenitor cell strain prior to treatment with 7,12-dimethylbenz[a]anthracene (DMBA). The steady-state levels of VL30 RNA in normal and papilloma cells were regulated by extracellular Ca2+ (which controls proliferation and differentiation in normal epidermal keratinocytes) and culture density. In contrast, steady-state levels of VL30 RNA were not regulated by these factors in the squamous cell carcinoma or the anaplastic carcinoma cells. VL30 expression was Ca2+ dependent in the initiated cell precursors within each tumor cell lineage, suggesting that the loss of response to extracellular Ca2+ was associated with the malignant conversion stage of carcinogenesis. No differences between normal and tumor cells were found in the cellular RNA levels of five additional proto-oncogenes. The mouse epidermal cell model should provide a means for direct assessment of a potential functional role of VL30 sequences in cancer development.
Grace Cancer Drug Center, Roswell Park Memorial Institute, Buffalo, New York 14263.
K A
KA
Han
P
P
Rothberg
M
M
Kulesz-Martin
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002452:Cell Count; D002454:Cell Differentiation; D002471:Cell Transformation, Neoplastic; D015870:Gene Expression; D051379:Mice; D008807:Mice, Inbred BALB C; D027383:Papillomaviridae / Q000235:genetics; D011519:Proto-Oncogenes; D012313:RNA / Q000378:metabolism*; D012367:RNA, Viral / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D012878:Skin Neoplasms / Q000235:genetics* / Q000473:pathology; D013728:Terminator Regions, Genetic; D014407:Tumor Cells, Cultured
D012367:RNA, Viral; D012313:RNA; D002118:Calcium