Role of CRD-BP in the growth of human basal cell carcinoma cells.

Although the number of new cases of basal cell carcinoma (BCC) has increased rapidly in the last few decades, the molecular basis of its pathogenesis is not completely understood. Activation of the Hedgehog (Hh) signaling pathway has been shown to be a key factor driving the development of BCC. The Wnt/ß-catenin signaling pathway was also shown to be activated in BCCs and to perhaps modulate the activity of the Hh pathway. We have previously identified a mechanism by which Wnt signaling regulates the transcriptional outcome of the Hh signaling pathway. We demonstrated that coding region determinant-binding protein (CRD-BP), a direct target of the Wnt/ß-catenin signaling, binds to GLI1 mRNA, stabilizes it, and consequently upregulates its levels (mRNA and protein) and activities. We hypothesized that Wnt-induced and CRD-BP-dependent regulation of GLI1 expression and activities is important for the development of BCC. In this study, we show that CRD-BP is overexpressed in BCC and that its expression positively correlates with the activation of both Wnt and Hh signaling pathways. We also describe the generation and characterization of a human BCC cell line. This cell line was utilized to demonstrate the importance of CRD-BP-dependent regulation of GLI1 expression and activities in the development of BCC.

Short-term vitamin A supplementation does not affect bone turnover in men.

Limited data in humans and animals indicate that excess vitamin A stimulates bone resorption and inhibits bone formation, effects that over time might lead to bone loss and fracture. Thus, it is possible that vitamin A supplementation is a currently unrecognized risk factor for the development of osteoporosis. To further evaluate this possibility, a prospective, randomized, single-blind study of vitamin A supplementation was conducted in 80 healthy men age 18-58 y. One half received 7576 microg (25,000 IU) of retinol palmitate daily with their evening meal; the others took a placebo. Blood was collected from fasting subjects and serum prepared at baseline and after 2, 4 and 6 wk of supplementation. Serum bone specific alkaline phosphatase (BSAP) and N-Telopeptide of type 1 collagen (NTx) were measured at all time points. Serum osteocalcin (Oc) was measured at baseline and after 6 wk of supplementation. BSAP, NTx and Oc did not differ between the supplemented and placebo-treated groups over the course of the study. In conclusion, short-term vitamin A supplementation at this dosage in healthy men does not alter serum markers of skeletal turnover. Thus, it is unlikely that short-term administration of vitamin A would contribute to the development of osteoporosis. Whether long-term vitamin A supplementation might have adverse skeletal effects remains to be determined.