Expression pattern of cisplatin-induced metallothionein isoforms in squamous cell carcinoma

Cisplatin (CDDP) is a useful drug for the treatment of malignant solid tumors of the head and neck. Because CDDP includes the heavy metal platinum as a component, it is thought metallothionein (MT) may be involved in CDDP-resistance. However, functional differences between the four MT isoforms (MT-I, II, III and IV) remain unclear. The aim of this study was to investigate the relationship between MT isoform expression and CDDP-resistance. Two human tongue squamous cell carcinoma cell lines not exposed to anticancer chemotherapy were studied. The cell lines were subjected to reverse transcriptase-polymerase chain reaction (RT-PCR) analysis before and after CDDP-treatment. Both cell lines expressed MT-I/II and MT-IV isoforms but not the MT-III isoform. Following CDDP treatment, MT-I/II mRNA levels were induced only in the CDDP-resistant cell line. Our results showed that expression of the MT I/II isoform was induced by CDDP treatment, and may play an important role in CDDP-resistance in squamous cell carcinoma of the human tongue.