1α, 25-Dihydroxyvitamin D3 and the vitamin D receptor regulates ΔNp63α levels and keratinocyte proliferation

Abstract

1α, 25-dihydroxyvitamin D3 (VD3), a secosteriod that has been explored as an anti-cancer agent, was also shown to promote cell survival. Its receptor, the Vitamin D Receptor (VDR), is a direct target of the proto-oncogene ΔNp63α, which is overexpressed in non-melanoma skin cancers. The interconnection between VDR/VD3 signaling and ΔNp63α, led us to examine whether VDR/VD3 signaling promotes keratinocyte proliferation by regulating ΔNp63α levels. Our data demonstrate that VDR regulates ΔNp63α expression at both the transcript and protein level. Interestingly, although low doses of VD3 led to an increase in ΔNp63α protein levels and keratinocyte proliferation, high doses of VD3 failed to increase ΔNp63α protein levels and resulted in reduced proliferation. Increased expression of ΔNp63α by low dose VD3 was shown to be dependent on VDR and critical for the proliferative effects of VD3. VD3-mediated increases in ΔNp63α protein levels occur via activation of both p38 MAPK and Akt kinases. Finally, analysis of samples from patients with squamous cell carcinoma (SCC), basal cell carcinoma and precursors to invasive SCC demonstrated a significant correlation between p63 and VDR levels when compared with healthy normal skin control samples. Delineation of the mechanisms by which VD3 exerts its effect on ΔNp63α and cell proliferation is critical for determining the future of VD3 in cancer therapies.

ERK3 is transcriptionally upregulated by ∆Np63α and mediates the role of ∆Np63α in suppressing cell migration in Non-Melanoma Skin Cancers

“…Skin tissue microarrays used in this study included normal skin (N=53), a precursor to squamous cell carcinoma/actinic keratosis (AK) (N=66), cutaneous squamous cell carcinoma (SCC) (N=59) and cutaneous basal cell carcinoma (BCC) (N=57) sections (Additional le 7: Table S1). Consistent with a previous report from our lab [6], ΔNp63α is signi cantly upregulated in AK, SCC and BCC skin tissues compared with normal skin ( Figure 1A and B and Additional le 8: Table S2). ERK3 protein was also shown to be expressed in all four types of skin sections and mainly localized to the cytoplasm of the cells ( Figure 1A and C and Additional le 8: Table S2).…”

“…Formalin-xed, para n-embedded human skin tissue microarrays described previously [6] were used for co-immunostaining studies. Human tissue samples consisted of normal skin (N=53), actinic keratosis (AK) (N=66), cutaneous squamous cell carcinoma (SCC) (N=59), and basal cell carcinoma of the skin (BCC) (N=57).…”

“…Human tissue samples consisted of normal skin (N=53), actinic keratosis (AK) (N=66), cutaneous squamous cell carcinoma (SCC) (N=59), and basal cell carcinoma of the skin (BCC) (N=57). Skin tumor and non-tumor skin tissue slides were co-stained for p63 and ERK3 as previously described with some modi cations [6,10]. Brie y, the staining of both p63 and ERK3 were performed using heat-based antigen retrieval processes with a citrate buffer (10 mM sodium citrate, 0.05% Tween-20, pH 6.0).…”

A new sensitive LC/MS/MS analysis of vitamin D metabolites using a click derivatization reagent, 2-nitrosopyridine

“…In the kidney, 25(OH)VitD is further hydroxylated to 1,25-dihydroxyvitamin D [1,25(OH) 2 VitD]. 1,25(OH) 2 VitD is the major biologically active metabolite and plays an important role in decreasing the risk of many diseases, including common cancers, cardiovascular disease, autoimmune disease, and chronic kidney disease (13)(14)(15)(16)(17). Most recently, we have demonstrated that 1,25(OH) 2 VitD also appears to be important for the health of the eye (18).…”

Vitamin D and Human Reproduction

“…Also, 1,25(OH)2D3 blocks mitogenic signaling, including that of estrogen, epidermal growth factor (EGF), and insulin-like growth factor 1, and upregulates growth inhibitors such as transforming growth factor β (TGF-β) [178]. In addition, 1,25(OH)2D3 activates VDR-mediated apoptosis [179].…”