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The involvement of Grainyhead-like (GRHL) transcription factors in various cancers is well documented. However, little is known about their role in clear cell renal cell carcinoma (ccRCC). We discovered that the expression of two of these factors-GRHL1 and GRHL2-are downregulated in ccRCC samples, and their expression is correlated with the expression of VHL gene. This suggests a functional link between the GRHL transcription factors and one of the best known tumor suppressors. Although the GRHL genes are not mutated in ccRCC, some of the single nucleotide polymorphisms in these genes may indicate an increased risk of ccRCC development and/or may allow to assess patients' prognoses and predict their responses to various forms of therapy. Silencing of GRHL2 expression in non-tumorigenic kidney cell line results in increased cell proliferation, increased resistance to apoptosis, as well as changes in the levels of selected proteins involved in the pathogenesis of ccRCC. These changes support the potential role for GRHL2 as a suppressor of ccRCC.

The LSF/Grainyhead family of transcription factors consists of proteins whose structure and functions have been preserved in the course of eukaryotic evolution--from primitive unicellular life forms to complex multicellular organisms. In the latter, these factors display tissue specificity and are active mainly in the covering epithelium. The roles of GRH factors are associated with regulation of expression of genes essential for correct differentiation and functioning of the epithelia of ectodermal origin. The Grh gene expression profiles are diverse and variable, especially during embryonic development. Research on the role of GRHL transcription factors is carried out on cellular and organismal level. In experimental animals, aberrant Grh gene expression leads to many diseases, including failure of epidermal wound healing and neural tube defects. Changes of these genes' expression levels are also linked to carcinogenesis. GRHL transcription factors participate in signaling pathways involved in cellular proliferation and apoptosis.

To examine how the higher expression level of CYP3A4 isoenzyme influenced the cytotoxicity of the antitumor triazoloacridinone derivative C-1305 in Chinese hamster ovary (CHO) cells.Three CHO cell lines were examined: wild-type CHO cells; CHO-HR cells with overexpression of human cytochrome P450 reductase (CPR); and CHO-HR-3A4 cells with coexpression of human CYP3A4 and CPR. Cellular responses caused by C-1305 were monitored using DAPI staining, cell cycle analysis, phosphatydilserine externalization analysis and SA-β-galactosidase expression analysis. Cell viability was assessed with simultaneous FDA and PI staining.Treatment with C-1305 for 72 h exhibited different levels of cytotoxicity in the 3 cell lines, and the values of IC80 in CHO, CHO-HR and CHO-HR-3A4 cells were 0.087±0.005, 0.032±0.0001, and 0.064±0.0095 μmol/L, respectively. The cell cycle analysis revealed that both CHO and CHO-HR cells underwent transient G(2)/M arrest, whereas CHO-HR-3A4 cells did not accumulate in this phase. Prolonged exposure up to 120 h caused time-dependent increase in the sub-G(1) fraction in all the 3 cell lines. Treatment with C-1305 caused cell death through apoptosis and necrosis. However, these processes were more pronounced in the transfected CHO cells than in the wild-type cells. The cells surviving after C-1305 exposure underwent senescence.CYP3A4 overexpression potently enhances the cellular responses (apoptosis, necrosis and senescence) caused by C-1305 in CHO cells.