High basal NF-κB activity in nonpigmented melanoma cells is associated with an enhanced sensitivity to vitamin D3 derivatives

Abstract

Background:Melanoma is highly resistant to current modalities of therapy, with the extent of pigmentation playing an important role in therapeutic resistance. Nuclear factor-κB (NF-κB) is constitutively activated in melanoma and can serve as a molecular target for cancer therapy and steroid/secosteroid action.Methods:Cultured melanoma cells were used for mechanistic studies on NF-κB activity, utilising immunofluorescence, western blotting, EMSA, ELISA, gene reporter, and estimated DNA synthesis assays. Formalin-fixed, paraffin-embedded specimens from melanoma patients were used for immunocytochemical analysis of NF-κB activity in situ.Results:Novel 20-hydroxyvitamin (20(OH)D3) and classical 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) secosteroids inhibited melanoma cell proliferation. Active forms of vitamin D were found to inhibit NF-κB activity in nonpigmented cells, while having no effect on pigmented cells. Treatment of nonpigmented cells with vitamin D3 derivatives inhibited NF-κB DNA binding and NF-κB-dependent reporter assays, as well as inhibited the nuclear translocation of the p65 NF-κB subunit and its accumulation in the cytoplasm. Moreover, analysis of biopsies of melanoma patients showed that nonpigmented and slightly pigmented melanomas displayed higher nuclear NF-κB p65 expression than highly pigmented melanomas.Conclusion:Classical 1,25(OH)2D3 and novel 20(OH)D3 hydroxyderivatives of vitamin D3 can target NF-κB and regulate melanoma progression in nonpigmented melanoma cells. Melanin pigmentation is associated with the resistance of melanomas to 20(OH)D3 and 1,25(OH)2D3 treatment.

Vitamin D in cancer chemoprevention

“…Likewise, a similar effect was observed by other authors on colorectal cancer cells (Schwab et al, 2007) and prostate cancer cells (Krishnan & Feldman, 2010). Nevertheless, as opposing results have been also reported on the effects of Vit D on NF-kB expression levels (Bao et al, 2010;Janjetovic et al, 2011;Krishnan et al, 2007) further studies may better define the role of NF-kB in autophagy and, consequently, the potential therapeutic impact of Vit D in modulating this phenomenon in cancer cells.…”

“…This phenomenon may results in an inhibition of IFN-g induced activation and potentiation of lysosomal activity of macrophages, recruitment of autophagic proteins, and, ultimately, may lead to a decrease of autophagy Wu and Sun (2011) NF-kB expression (?) Bao et al (2010), Krishnan and Feldman (2010), Tse et al (2010), andJanjetovic et al (2011) Induced expression of thioredoxin reductase 1 (TXNRD1) Swami et al (2003), Peehl et al (2004), Kovalenko et al (2010) Antioxidant defense and DNA repair Increased production of superoxide dismutase 1 and 2 (SOD1 and SOD2) in prostate epithelial cells (PECs) and in androgen-sensitive prostate cancer cells (LNCaP) Peehl et al (2004) and Lambert et al (2006) Increase of glucose-6-phosphate dehydrogenase (G6PDH) expression levels Zhang et al (2005), Bao et al (2008), and Kovalenko et al (2010) Induction of nuclear factor erythroid-derived 2-like 2 (NFE2L2) transcription factor that controls the gene expression of several enzymes of the antioxidants systems such as glutathione peroxidase (GPX) 3, heme oxygenase 1 (HMOX-1), and aldo-keto reductase 1C2(AKR1C2)…”

Hydroxylation of CYP11A1-Derived Products of Vitamin D3 Metabolism by Human and Mouse CYP27B1

“…Along with the primary products of CYP11A1 action on vitamin D3, 17,20(OH) 2 D3, 20,22(OH) 2 D3, and 20,23(OH) 2 D3, we have a unique set of derivatives all containing a 20-hydroxyl group plus one additional hydroxyl group at every position on the side chain, except C21 (note that C26 and C27 are equivalent). All of these 20-hydroxy derivatives have been shown to be biologically active (Zbytek et al, 2008;Janjetovic et al, 2009Janjetovic et al, , 2010Janjetovic et al, , 2011Li et al, 2010;Slominski et al, 2010Slominski et al, , 2011Slominski et al, , 2012aTang et al, 2010a;Tuckey et al, 2011;Kim et al, 2012;Lu et al, 2012;Wang et al, 2012). The low catalytic efficiency of CYP27B1 toward 20(OH)D3 is greatly enhanced when the second hydroxyl group is added toward the end of the side chain, as seen for 24,20(OH) 2 D3, 20,25(OH) 2 D3, and 20,26(OH) 2 D3.…”

“…It has been documented that the CYP11A1-derived vitamin D3 analogs, 20(OH)D3 and 20,23(OH) 2 D3, display similar properties to 1,25(OH) 2 D3, such as inhibiting cell proliferation, promoting differentiation of keratinocytes and leukemia cells, and suppressing tumorigenicity of melanoma (Zbytek et al, 2008;Janjetovic et al, 2009Janjetovic et al, , 2011Li et al, 2010;Slominski et al, 2010Slominski et al, , 2012aTuckey et al, 2011;Kim et al, 2012;Lu et al, 2012;Wang et al, 2012).…”

“…Via binding to the vitamin D receptor, these compounds can inhibit keratinocyte, melanoma, leukemia, breast, and liver cancer cell proliferation; promote differentiation; and display antiinflammatory activity by decreasing nuclear factor-ĸB activity (Zbytek et al, 2008;Janjetovic et al, 2009Janjetovic et al, , 2010Janjetovic et al, , 2011Li et al, 2010;Slominski et al, 2010Slominski et al, , 2011Slominski et al, , 2012aTang et al, 2010a;Tuckey et al, 2011;Kim et al, 2012;Lu et al, 2012;Wang et al, 2012). Importantly, all three of these derivatives lack calcemic activity in rodents, even at relatively high doses (Slominski et al, , 2013aWang et al, 2012).…”