GP-02 SYNERGISTIC EFFECTS OF CALCIPOTRIENE, A VITAMIN D ANALOG, AND TRETINOIN, A VITAMIN A ANALOG, ON CELL VIABILITY OF A DYSPLASTIC ORAL KERATINOCYTE CELL LINE
Abstract
Context: Dysplastic oral leukoplakia (OL) lesions, or white patches within the oral mucosa, are premalignant lesions that may progress to oral squamous cell carcinoma (OSCC). Data suggest anywhere from 11-36% of OL will transform to OSCC if left untreated. Several clinical studies have utilized either vitamin A or vitamin D synthetic derivatives in topical formulations for the treatment of dysplastic OL but using a combination of the two drugs together has not been examined. In addition, to the best of our knowledge, cell culture studies using oral dysplastic cell lines treated with either vitamin A derivatives, vitamin D derivatives, or a combination of both are lacking. Vitamin A and vitamin D derivatives have distinct unique mechanisms, which when used together could exhibit synergistic effects.
Objective: To determine the effect of a drug combination of a vitamin A and a vitamin D derivative on the viability of human dysplastic oral keratinocytes, compared to monotherapy with each agent. It is hypothesized that the combination of these synthetic derivatives would result in a synergistic cytotoxic effect, compared to the use of each drug individually.
Methods: A dysplastic oral keratinocyte (DOK) cell line was cultured according to provider instructions. Cells were treated with various concentrations of single drug A tretinoin (a vitamin A derivative), various concentrations of single drug B calcipotriene (a vitamin D derivative), or various combinations of the two vitamin derivatives together (A+B). Cells were plated in 96 well plates and treated with the drugs or vehicle control (DMSO) for 24, 48, and 72 hours. Cell viability was measured utilizing a MTT assay. The effect of the combination between calcipotriene and retinoic acid on cell viability was calculated for the 72-hour time point utilizing CompuSyn software.
Results: The half-maximal inhibitory concentration (IC50) was able to be determined for tretinoin, but not for calcipotriene. Still, results show that the addition of the two drugs together had a more profound inhibitory effect on cell viability than either drug by itself: the IC50 for tretinoin monotherapy was 90 µM, while IC50 for tretinoin + 0.25x calcipotriene was 50 µM. Furthermore, analysis of the experimental data in combination with simulation values from the CompuSyn software indicated a slight synergism for 2 of the 5 combinations tested here and a favorable dose reduction of 1.4-fold for tretinoin.
Conclusion: The study results provide evidence that there may be a synergistic effect when using calcipotriene and tretinoin in combination. Additional experiments are being performed, including finding a drug concentration that will give a more accurate dose-response curve for calcipotriene.
GP-02 SYNERGISTIC EFFECTS OF CALCIPOTRIENE, A VITAMIN D ANALOG, AND TRETINOIN, A VITAMIN A ANALOG, ON CELL VIABILITY OF A DYSPLASTIC ORAL KERATINOCYTE CELL LINE
Context: Dysplastic oral leukoplakia (OL) lesions, or white patches within the oral mucosa, are premalignant lesions that may progress to oral squamous cell carcinoma (OSCC). Data suggest anywhere from 11-36% of OL will transform to OSCC if left untreated. Several clinical studies have utilized either vitamin A or vitamin D synthetic derivatives in topical formulations for the treatment of dysplastic OL but using a combination of the two drugs together has not been examined. In addition, to the best of our knowledge, cell culture studies using oral dysplastic cell lines treated with either vitamin A derivatives, vitamin D derivatives, or a combination of both are lacking. Vitamin A and vitamin D derivatives have distinct unique mechanisms, which when used together could exhibit synergistic effects.
Objective: To determine the effect of a drug combination of a vitamin A and a vitamin D derivative on the viability of human dysplastic oral keratinocytes, compared to monotherapy with each agent. It is hypothesized that the combination of these synthetic derivatives would result in a synergistic cytotoxic effect, compared to the use of each drug individually.
Methods: A dysplastic oral keratinocyte (DOK) cell line was cultured according to provider instructions. Cells were treated with various concentrations of single drug A tretinoin (a vitamin A derivative), various concentrations of single drug B calcipotriene (a vitamin D derivative), or various combinations of the two vitamin derivatives together (A+B). Cells were plated in 96 well plates and treated with the drugs or vehicle control (DMSO) for 24, 48, and 72 hours. Cell viability was measured utilizing a MTT assay. The effect of the combination between calcipotriene and retinoic acid on cell viability was calculated for the 72-hour time point utilizing CompuSyn software.
Results: The half-maximal inhibitory concentration (IC50) was able to be determined for tretinoin, but not for calcipotriene. Still, results show that the addition of the two drugs together had a more profound inhibitory effect on cell viability than either drug by itself: the IC50 for tretinoin monotherapy was 90 µM, while IC50 for tretinoin + 0.25x calcipotriene was 50 µM. Furthermore, analysis of the experimental data in combination with simulation values from the CompuSyn software indicated a slight synergism for 2 of the 5 combinations tested here and a favorable dose reduction of 1.4-fold for tretinoin.
Conclusion: The study results provide evidence that there may be a synergistic effect when using calcipotriene and tretinoin in combination. Additional experiments are being performed, including finding a drug concentration that will give a more accurate dose-response curve for calcipotriene.