Transcription Regulation and Protein Subcellular Localization of the Truncated Basic Hair Keratin hHb1-ΔN in Human Breast Cancer Cells

The study explored the transcription regulation and subcellular localization of the truncated hair keratin hHb1-ΔN in human breast cancer cells. It found that hHb1-ΔN transcription was initiated at a cryptic promoter within the fourth intron of the hHb1 gene, with Sp1 and Sp3 transcription factors playing a crucial role. DNA demethylation increased hHb1-ΔN expression, suggesting epigenetic regulation. The protein was shown to integrate into the cytoskeleton network, potentially affecting cancer cell adhesion, but did not disrupt the cytokeratin network. The unique expression of hHb1-ΔN in cancer cells, absent in normal tissues, indicated its association with carcinogenesis and potential implications for cancer progression.