Phorbol ester‐responsive H‐ras1 gene promoter contains multiple TPA‐inducible/AP‐1‐binding consensus sequence elements

Abstract

We have constructed recombinant DNA plasmids which carry both the aminoglycoside phosphotransferase (aph) gene and the chloramphenicol acetyl-transferase (CAT) gene linked to the human normal or mutant T24 H-rasl promoter. We have transfected these plasmids into rat 208F fibroblasts using the calcium phosphate technique and selected for stable transformants by geneticin resistance. These transformants expressed CAT activity at low levels. However, when treated with the phorbol ester TPA, CAT levels increased substantially. Cells transfected with recombinant plasmids carrying a promoterless CAT gene did not respond to TPA. We have noted four motifs in the H-rasl promoter region which resemble TPA-inducible and AP-l-binding consensus sequences. We suggest that AP-l-like proteins may play a role in control of H-rasl transcription.H-rasl Promoter; Phorbol ester

Regulation of the Rb Gene by Normal and Mutated Ras, Tpa and Egf

“…Also, it has been reported that TPA can induce expression of a CAT gene linked to the human H-ra.s 1 promoter region (21). We found that TPA activates the transcription of Rb gene.…”

“…Plasmid P+53ACAT is the 5' deletion constract of pRbCAT2 (20). Plasmid p201 carry the aph gene and the CAT gene linked to the human mutant T24 Η-ras promoter region (21). Plasmids pHOöTl and pH06Nl contains the 6.6 Kb of the mutant and normal Η-ras gene, respectively (22).…”

Molecular Mechanisms of Ultraviolet Radiation Carcinogenesis

“…Interestingly, Ledwith et al (1990) have shown that anti-sense fos RNA can cause partial reversion of the transformed phenotypes including, density-dependent growth arrest, reversion to a flat cell morphology, inhibition of anchorage-independent growth, and inhibition of tumorigenicity, induced by a mutant H a m s oncogene in NIH 3T3 cells. Thus, fos appears to mediate downstream effects of ras-stimulated signal transduction, although fos may amplify the proliferative signal by looping back and binding to tumor promoter responsiveIAP-1 binding consensus sequence elements, thus up-regulating ras transcriptional levels (Spandidos et al, 1988).…”

“…In contrast, Gerhard et al (1987) have reported that the presence of rare Ha-ras-1 alleles is no more frequent among sporadic melanoma patients than in normal populations, suggesting that other genes must be associated with hereditary predisposition to melanoma. Spandidos and Wilkie (1988) have shown that the normal c-H a m s gene can suppress transformation induced by the mutated ras gene. Kitayama et al (1989) have reported that overexpression of a ras-related gene induced reversion to a normal phenotype in cells transformed with a mutant K-ras allele.…”

“…Spandidos and Wilkie (1988) have shown that the normal c-Ha-ras gene can suppress transformation induced by the mutated ras gene. Kitayama et al (1989) have reported that overexpression of a ras-related gene induced reversion to a normal phenotype in cells transformed with a mutant K-ras allele.…”