In addition, exogenous Δ40p53 expression significantly suppressed cell growth in HCC cells with wild-type TP53, and in those that were mutant or null for TP53 Notably, Δ40p53α-induced tumor suppressor activity was markedly attenuated in cells expressing the hot-spot mutant Δ40p53α-R175H, which lacks the transcription factor activity of p53.
Ectopic expression of this truncated domain significantly suppressed G1/S-phase transition, cellular proliferation, and tumour formation of RK3E-p53(R175H) /Rsf-1/cyclin E1 cells.
Since tumor cells face glucose and growth factor shortage when growing distant from sites of vascularization, we used genetically-matched human C8161 melanoma harbouring wt p53 or a tumor-associated (DN) mutant p53 (R175H), to investigate whether this mutation influences survival under metabolic stress.
In vitro, the R175L mutant displayed an attenuated tumor suppressor activity in the regulation of transcription, colony formation, and apoptosis when compared with wild-type p53 and the R175H mutant.
To understand the relevance of p53 missense mutations in vivo, we generated a mouse containing an arg-to-his substitution at p53 amino acid 172, which corresponds to the R175H hot-spot mutation in human tumors by homologous recombination.