MART-10, a less calcemic vitamin D analog, is more potent than 1α,25-dihydroxyvitamin D3 in inhibiting the metastatic potential of MCF-7 breast cancer cells in vitro

With the recent advance in breast cancer therapy, the survival rate of breast cancer patients has improved greatly. In spite of the progress, 25-50% of breast cancer patients eventually will develop metastasis. Due to limited early detection methods, metastasis is usually diagnosed at the late stages beyond recovery likely due to resistance to currently available breast cancer therapies. Thus, a new strategy to prevent cancer cell growth and repress tumor metastasis is desirable. The active form of vitamin D3, 1α,25-dihydroxyvitamin D3 [1α,25(OH)2D3], has anti-invasion and anti-migration properties in pre-clinical studies, yet its clinical application has been hampered by its hypercalcemic side effect. Previously, we have demonstrated that a new class of less-calcemic vitamin D analog, 19-nor-2α-(3-hydroxypropyl)-1α,25-dihydroxyvitamin D3 (MART-10), is 1000-fold more active than 1α,25(OH)2D3 in suppressing MCF-7 cells growth through cell cycle arrest and apoptosis induction. In the current study, we show for the first time that MART-10 is more active than 1α,25(OH)2D3 in preventing MCF-7 cell invasion and migration likely mediated through the upregulation of E-cadherin, and the downregulation of Snail, Slug, and Twist, the transcription factors implicated in epithelial-mesenchymal transition (EMT), as well as MMP-13. Based on the current in vitro and the highly anti-tumor characteristics of MART-10 in a pancreatic xenograft model, MART-10 is deemed as a promising candidate for breast cancer treatment. Further in vivo animal study comparing MART-10 with 1α,25(OH)2D3 and other potent and less calcemic analogs of vitamin D is warranted.

MART-10, a novel vitamin D analog, inhibits head and neck squamous carcinoma cells growth through cell cycle arrest at G0/G1 with upregulation of p21 and p27 and downregulation of telomerase

For the head and neck squamous cell carcinoma (HNSCC), surgery in combination with radiation therapy is the current standard treatment. However, the complex anatomy and important functions over the head and neck region often make HNSCC patients with severe comorbidities. Even after aggressive treatment, the 5year survival for HNSCC patients is only around 61%. Thus, new therapeutic regimens against HNSCC are urgently needed. 1α,25-Dihydroxyvitamin D3 [1α,25(OH)2D3] is a potent anti-tumor agent in a variety of pre-clinical studies, but its clinical application is impeded by hypercalcemic side effect. A new class of less-calcemic 1α,25(OH)2D3 analog, MART-10 (19-nor-2α-(3-hydroxypropyl)- 1α,25-Dihydroxyvitamin D3), has been shown to be much more potent than 1α,25(OH)2D3 in inhibiting cancer cell growth in vitro and in vivo without inducing hypercalcemia. In this study, we compared the antiproliferative activity of MART-10 with 1α,25(OH)2D3 and the mechanism responsible for the inhibition in FaDu and SCC-25 squamous carcinoma cells. Our results demonstrate that MART-10 is more potent than 1α,25(OH)2D3 in suppressing FaDu and SCC-25 cell growth through greater cell cycle arrest at G0/G1, accompanied by a greater downregulation of ki-67 expression and upregulation of p21 and p27. We also showed that telomerase expression in SCC-25 was suppressed to a greater extent by MART-10 than by 1α,25(OH)2D3. Thus, given the previously-proven in vivo antitumor effect and safety of MART-10 and bleak background of HNSCC, based on our current result, we concluded that MART-10 has a potential as a chemo-preventive and - therapeutic agent to treat HNSCC.