Fig. 6

Reduction of TXNIP expression in MCF-7 cells by 1,25(OH)₂D₃ is possibly ER-dependent. a–c 1,25(OH)₂D₃ (100 nM) treatment significantly reduces ER⍺ mRNA (72 h) and protein expression in MCF-7 cells. Relative expression was calculated using the ∆∆Ct method, with vinculin as the housekeeping gene. Statistical significance between DMSO- and 1,25(OH)₂D₃-treated cells is calculated using a two-tailed Student’s t test, where p values less than or equal to 0.05, 0.01, and 0.001 are depicted in the figures by *, **, and ***, respectively. Error bars ± SD; n = 3. Tamoxifen (10 μM) treatment (d), but not estradiol (100 nM) (e), reduces TXNIP protein expression in a time-dependent manner. f Non-significant regulation of TXNIP mRNA levels is observed in MCF-7 cells treated for 24 h with either tamoxifen or estradiol, alone and in combination with 1,25(OH)₂D₃. g Glucose uptake in MCF-7 cells is significantly reduced by various concentrations of tamoxifen (24 h), an effect that is significantly ablated in the presence of 1,25(OH)₂D₃. Estradiol reduces glucose uptake in a concentration-dependent manner, with 1,25(OH)₂D₃ only influencing regulation of glucose uptake in response to 10 nM treatment with estradiol