Calcitriol Reverses Induced Expression of Efflux Proteins and Potentiates Cytotoxic Activity of Gemcitabine in Capan-2 Pancreatic Cancer Cells

Abstract

ABSTRACT-Purpose. Efflux and influx proteins play a major role in chemo-resistance by affecting the net cellular uptake of anti-cancer drugs. Hence, alteration of the efflux and influx protein expression may result in variations of chemotherapeutics uptake and consequently cell death rate. The present study investigated the effects of pre-treatment of capan-2 pancreatic cancer cells with calcitriol, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA) or silibinin on the induction of three major efflux proteins and the main gemcitabine influx protein. The influence of the pre-treatments on the net cellular uptake of gemcitabine, total ATPase activity, and cell death rate were also evaluated. Methods. Capan-2 pancreatic cancer cells were pre-treated for 24 h with calcitriol, BHT, BHA, or silibinin, followed by gemcitabine treatment. The concentration of gemcitabine was quantified using ultra-performance liquid chromatography (UPLC). Real-time polymerase chain reaction (RT-PCR) was utilized in order to investigate the expression of the mRNAs. The expression of the proteins was assessed using western blotting. Measurement of the ATPase activity was conducted utilizing a colorimetric method and viability of the cells was determined using a luminescent cell viability assay. Results. Protein expression studies showed that BHT, silibinin, and BHA increased expression of the efflux proteins and decreased the overall uptake of gemcitabine, whereas calcitriol significantly inhibited expression of the efflux proteins and increased gemcitabine uptake. Expression of specific mRNAs correlated reasonably well with the levels of corresponding proteins. Additionally, the expression of efflux proteins and ATPase activity were well correlated, signifying that the induced efflux proteins are functionally active. Moreover, pre-treatment with calcitriol resulted in a significant increase in cell death with gemcitabine treatment, whereas, BHA significantly reduced the cell death rate. On the other hand, pre-treatment with BHT and silibinin had no significant effect on the cell death rate. Conclusions. Pre-treatment of the pancreatic cancer cells with calcitriol significantly increased gemcitabine cellular uptake and consequently decreased cell viability after treatment with gemcitabine, whereas BHA significantly reduced gemcitabine uptake and decreased cell death rate, which were at least partially attributed to the alteration of expression of efflux and influx proteins.

Vitamin D promotes the cisplatin sensitivity of oral squamous cell carcinoma by inhibiting LCN2-modulated NF-κB pathway activation through RPS3

“…Vitamin D has been found to have antitumour effects, suggesting that it might inhibit the progression of rectal cancer 10 , breast cancer 11 , pancreatic cancer 12,13 , head and neck cancers 14 and other cancers. Urashima 15 suggested that the higher the serum level of vitamin D is, the better is the prognosis of rectal cancer patients.…”

Silymarin (milk thistle extract) as a therapeutic agent in gastrointestinal cancer

“…In one study, Capan-2 pancreatic cancer cells were pretreated with BHT, BHA, calcitriol, or silibinin for 24 h, and then treated with gemcitabine [ 89 ]. BHT, BHA and silibinin all up-regulated the expression levels of efflux proteins and decreased gemcitabine uptake, while calcitriol strongly suppressed the expression of efflux proteins, and increased gemcitabine uptake.…”

“…Pre-treatment with calcitriol protected the cells against gemcitabine toxicity, while BHA increased the cell death rate. Neither BHT nor silibinin had any significant effect on the cell death rate [ 89 ].…”

Pancreatic Cancer (PDAC): Introduction of Evidence-Based Complementary Measures into Integrative Clinical Management

“…Combining chemotherapy with vitamin D has been under consideration for several years. Overall, the results of such combination treatments have been consistently beneficial [ 214 , 215 , 216 , 217 ]. This conclusion was verified and extended in an experiment on a mouse model, showing that supplementing gemcitabine with calcipotriol (a synthetic derivative of vitamin D) significantly increased median survival by some 50% ( Figure 9 B) [ 218 ].…”