Anticancer drugs and the regulation of Hedgehog genes GLI1 and PTCH1, a comparative study in nonmelanoma skin cancer cell lines.

Nonmelanoma skin cancer is the most common cancer in humans, comprising mainly basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). BCC proliferation is highly dependent on the Hedgehog signaling pathway. We aimed to investigate a panel of anticancer drugs with known activity against skin cancer for their therapeutic potential in localized, enhanced topical treatment of SCC and BCC. Cytotoxicity profiles for vismodegib, 5-fluorouracil (5-FU), methotrexate (MTX), cisplatin, bleomycin, and vorinostat were established in terms of half maximal inhibitory concentration values in a panel of immortalized keratinocytes (HaCaT), BCC (UWBCC1 and BCC77015), and SCC (A431 and SCC25) cell lines. The impact of treatment on the regulation of Hedgehog pathway target genes (GLI1 and PTCH1), measured by real-time PCR, was compared between UWBCC1 and HaCaT. Varying cell line sensitivity profiles to the examined anticancer drugs were observed. Generally, 24-h drug exposure was sufficient to reduce cell viability. We found that 5-FU, MTX, and cisplatin significantly downregulated the expression of two genes controlled by the Hedgehog pathway (≤25-, 2.9-, and 12.5-fold, respectively, for GLI1 in UWBCC1 cells at 48 h, P<0.0001). The gene regulation showed clear concentration dependence and correlated with cytotoxicity for both 5-FU and MTX. We find a potential for the use of anticancer drugs in localized and enhanced topical treatment of nonmelanoma skin cancer. Of importance in the clinical setting, 24-h drug exposure may be sufficient for significant cytotoxicity for vismodegib, 5-FU, cisplatin, and bleomycin. MTX, 5-FU, and cisplatin may offer particular promise through combined cytotoxicity and downregulation of Hedgehog pathway genes GLI1 and PTCH1.