OBJECTIVETo provide experimental evidence for the folate receptor 1 (FOLR1) mediated targeted cancer therapy and resistance reversal, the FOLR1 expression differences in nasopharyngeal carcinoma cells (CNE-1) and immortalized normal nasopharyngeal cells (NP69) and the correlation between FOLR1 expression and paclitaxel resistance index in nasopharyngeal carcinoma were investigated.

METHODSThe expressions of FOLR1 in CNE-1, CNE-1/Taxol (paclitaxel-resistance cells) and NP69 was detected by cDNA microarray, reverse transcriptase-polymerase chain reaction (RT-PCR), Western blot and immunocytochemistry. Proliferation inhibition rates of CNE-1 and CNE-1/Taxol cells were measured by colony formation assay after treated by short interfering RNA (siRNA) of FOLR1.

RESULTSThe expressions of FOLR1 gene in CNE-1/Taxol cells and CNE-1 cells were 2636.0 and 176.0, respectively. The expression of FOLR1 was not detected in the NP69 by semi-quantative RT-PCR and Western blot. The high expression of FOLR1 in CNE-1/Taxol was verified by semi-quantative RT-PCR, and its expression level was positively correlated to the degree of drug-resistance (r(2) = 0.8719). The results were also validated by Western blot and immunocytochemistry. The sensitivity of CNE-1/Taxol to paclitaxel significantly increased after inhibition of FOLR1 gene expression by siRNA, and its IC(50) value was decreased by 59.6% (t = 6.92, P < 0.01).

CONCLUSIONSThe expression of FOLR1 is closely related to the occurrence of NPC and Taxol resistance. FOLR1 gene may be one of the important target molecules in NPC treatment and reversion of the paclitaxel-resistance in NPC.