Tacalcitol is a calcitriol analogue, regulates calcium metabolism by stimulating intestinal calcium absorption and influencing bone turnover. But tacalcitol has no significant change in bone formation [1]. Tacalcitol can be used in the research of inflammation, breast cancer, and skin diseases, and prevent the osteoporosis that results from the development of cancer or from chemotherapy or hormone therapy [2-3].
In vitro, treatment of normal human keratinoeytes with tacalcitol (0.01-1μM; 48h) increased the numbers of involucrin positive cells and induced cell differentiation [4].
In vivo, tacalcitol (1.0µg/kg; s.c.; thrice weekly) decreased bone column density, transiently decreased the metastatic spread of 4T1 breast carcinoma without influencing primary tumour growth or angiogenesis in old ovariectomized (OVX) mice [2]. While tacalcitol (1.0µg/kg; s.c.; thrice weekly) increased metastatic spread in young mice bearing 4T1 breast cancer [5].
References:
[1] Yamada, S., J-P. Bonjour, and H. Fleisch. "Effect of 1α, 24 (R)-dihydroxyvitamin D3 on calcium metabolism in the rat." European Journal of Endocrinology 111.4 (1986): 572-576.
[2] Anisiewicz, Artur, et al. "Calcitriol analogues decrease lung metastasis but impair bone metabolism in aged ovariectomized mice bearing 4T1 mammary gland tumours." Aging and disease 10.5 (2019): 977.
[3] Matsumoto, Kunio, et al. "Effect of 1, 24R‐dihydroxyvitamin D3 on the growth of human keratinocytes." The Journal of Dermatology 17.2 (1990): 97-103.
[4] Kobayashi, Teruaki, et al. "1α, 24R‐dihydroxyvitamin D3 has an ability comparable to that of 1α,25‐dihydroxyvitamin D3 to induce keratinocyte differentiation." The Journal of Dermatology 17.11 (1990): 707-709.
[5] Anisiewicz, Artur, et al. "Unfavorable effect of calcitriol and its low-calcemic analogs on metastasis of 4T1 mouse mammary gland cancer." International journal of oncology 52.1 (2018): 103-126.