The effects of aranose, cisplatin or paclitaxel in monotherapy and in combination on the expression of Pd–l1 and Pd–l2 in melanoma cells

Abstract

Introduction . Currently, the following approaches are used for cancer treatment: surgical tumor removal, chemotherapy, targeted therapy and immunotherapy. The combination of different drugs may have additional advantages due to cumulative effect. Moreover, some additional effects like changes in PD–L1 and PD–L2 expression levels may be observed. Aim . The aim of this study was to determinate the influence of aranose, cisplatin or paclitaxel and their combination on the expression of mRNA level and proteins PD–L1 and PD–L2 in melanoma cell lines and to compare the results with the differentiation status and with the appearance of mutations in melanoma cells. Materials and methods . Melanoma cell lines used in this study were derived from surgical species of patients with disseminated melanoma. The mRNA expression level of PD–L1 and PD–L2 genes was measured by RQ-PCR. The expression of PD–L1 and PD–L2 proteins was measured by flow cytometry. The Pearson’s correlation and median test were used for statistical analysis. Results . The expression level of PD–L2 gene was correlated with melanomas cell’s differentiation status (Pearson’s coefficient 0.937, p <0.15). The expression levels of PD–L1 gene and PD–L1 and PD–L2 proteins were not correlated with differentiation status of melanoma cells as well as TP53 mutations. In case of BRAF mutations the expression of PD–L2 was low detectable (p = 0.0117). It is worth noting that the TP53 mutations were associated with BRAF mutations (Pearson’s coefficient 1, p <0.15). The exposure of cells to aranose led to increased PD–L1 gene expression (p = 0,23). Incubation with cisplatin in combination with paclitaxel also resulted in an increase in PD–L1 protein expression (p = 0.037). Cisplatin or paclitaxel had no effect on the expression of PD–L1 protein. The expression level of PD–L2 gene and protein decreased under the action of any of these two drugs: these data are statistically (p = 0.6). Conclusion. The tested drugs had no effect on the expression of PD–L1 and PD–L2 both at the protein level and at the mRNA level. It follows that the combination of anti-PD therapy and anticancer drugs, such as paclitaxel and aranose, will not potentially reduce the effectiveness of checkpoint therapy, and may have great prospects for future use in the creation of combined therapy protocols.