Elevated Expression of Osteopontin Splice Variants in Nonmelanoma Skin Cancer Compared to Normal Skin and Adult Keratinocytes

The study from May 2018 found that nonmelanoma skin cancers (CSCC and BCC) exhibit significantly higher levels of osteopontin (OPN) splice variants (OPN-a, OPN-b, and OPN-c) compared to normal skin and adult keratinocytes. Normal skin showed minimal expression of these OPN isoforms, while CSCC had similar levels of all OPN isoforms, and BCC had a notably higher expression of OPN-a over OPN-c. HaCaT keratinocytes, used as a model for human adult keratinocytes, displayed low levels of OPN-a and OPN-b and no detectable OPN-c. UVB treatment did not increase OPN expression in these cells, but calcitriol did stimulate expression of OPN-a and OPN-b. The findings indicate that OPN isoforms are upregulated in nonmelanoma skin cancers and that adult keratinocytes may not be the source of OPN-c expression.