To determine the relationship between 25(OH) vitamin D levels and non-melanoma skin cancer (NMSC), we performed a nested case–control study in ambulatory, elderly men enrolled in the Osteoporotic Fractures in Men (MrOS) Study. Health habit and medical history, including self-reported history of NMSC were recorded and 25(OH)D levels were measured on serum collected at baseline from a random sample of Caucasian MrOS subjects. Mean age (73 ± 5), BMI, daily vitamin D and calcium intake were similar in the men with (n = 178) and without NMSC (n = 930), but higher levels of 25(OH)D were associated with a decreased risk of having a history of NMSC (P trend  = 0.04). Men in the highest quintile of 25(OH)D (>30 ng/mL) had 47% lower odds of NMSC (95% CI: 0.30–0.93, p = 0.026) compared to those in the lowest quintile. Our results suggest that a diagnosis of NMSC is not a surrogate for adequate 25(OH)D levels or increased UV exposure, and high 25(OH)D levels may be associated with a reduced risk of NMSC.

Hedgehog pathway-dependent cancers can escape Smoothened (SMO) inhibition through mutations in genes encoding canonical hedgehog pathway components; however, around 50% of drug-resistant basal cell carcinomas (BCCs) lack additional variants of these genes. Here we use multidimensional genomics analysis of human and mouse drug-resistant BCCs to identify a noncanonical hedgehog activation pathway driven by the transcription factor serum response factor (SRF). Active SRF along with its coactivator megakaryoblastic leukemia 1 (MKL1) binds DNA near hedgehog target genes and forms a previously unknown protein complex with the hedgehog transcription factor glioma-associated oncogene family zinc finger-1 (GLI1), causing amplification of GLI1 transcriptional activity. We show that cytoskeletal activation through Rho and the formin family member Diaphanous (mDia) is required for SRF-MKL-driven GLI1 activation and for tumor cell viability. Remarkably, nuclear MKL1 staining served as a biomarker in tumors from mice and human subjects to predict tumor responsiveness to MKL inhibitors, highlighting the therapeutic potential of targeting this pathway. Thus, our study illuminates, for the first time, cytoskeletal-activation-driven transcription as a personalized therapeutic target for combatting drug-resistant malignancies.