Differential expression of ABCB1, ABCG2, and KLF4 as putative indicators for paclitaxel resistance in human epithelial type 2 cells.

Laryngeal squamous cell carcinoma (LSCC) is the second most common malignancy of the head and neck region in the USA with a declining 5-year survival rate. Paclitaxel resistance of tumors including LSCC still stands as a vital cause for poor clinical outcome in patients. In the current study, our aim was to explore the expressions of ATP-binding cassette transporters and stemness associated genes in human epithelial type 2 (Hep-2) cells with paclitaxel resistance. Resistant cells were developed via treatment with increasing doses of paclitaxel to acquire four sub-lines resistant to one-, two-, four-, and eightfold concentrations of paclitaxel (1×, 2×, 4×, 8×). Then, we profiled the expressions of ten selected ABC transporters (ABCA5, ABCB1, ABCB6, ABCC1, ABCC2, ABCC3, ABCC5, ABCC10, ABCF2, and ABCG2) and four stem cell markers (SOX2, OCT4, KLF, and CXCR4) using quantitative real time polymerase chain reaction in paclitaxel resistant cells to look for a link between these markers and chemoresistance. We demonstrated that ABCB1 and ABCG2 expressions gradually elevated and reached a maximum level in Taxol 8× cells. Considering stem cell markers, KLF4 expression elevated significantly, as soon as parental cells acquired resistance to the lowest dose of paclitaxel and its expression elevated stepwise. Expression levels of other tested ATP-binding cassette transporters and stem cell markers also elevated, although at different steps of paclitaxel resistance acquisition. Our findings suggest that higher expressions of ABCB1, ABCG2, and KLF4 might be considered as putative indicators for paclitaxel resistance in LSCC patients.