Expression of multidrug resistance genes MVP, MDR1, and MRP1 determined sequentially before, during, and after hyperthermic isolated limb perfusion of soft tissue sarcoma and melanoma patients.

PURPOSE: Isolated, hyperthermic limb perfusion (ILP) with recombinant human tumor necrosis factor alpha and melphalan is a highly effective treatment for advanced soft tissue sarcoma (STS) and locoregional metastatic malignant melanoma. Multidrug resistance (MDR)-associated genes are known to be inducible by heat and drugs; expression levels of the major vault protein (MVP), MDR1, and MDR-associated protein 1 (MRP1) were determined sequentially before, during, and after ILP of patients.

PATIENTS AND

METHODS

Twenty-one STS or malignant melanoma patients were treated by ILP. Tumor tissue temperatures were recorded continuously and ranged from 33.4 degrees C initially to peak values of 40.4 degrees C during ILP. Serial true-cut biopsy specimens from tumor tissues were routinely microdissected. Expression analyses for MDR genes were performed by real-time reverse transcriptase polymerase chain reaction and immunohistochemistry.

RESULTS

In 83% of the patients, MVP expression was induced during hyperthermic ILP. MVP-mRNA inductions often paralleled the increase in temperature during ILP. Increased MVP protein expressions either were observed simultaneously with the MVP-mRNA induction or were delayed until after the induction at the transcriptional level. Inductions of MDR1 and MRP1 were observed in only 13% and 27% of the specimens analyzed. Temperatures and drugs applied preferentially led to an induction of MVP and were not sufficient to induce MDR1 and MRP1 in the majority of tumors.

CONCLUSION

This study is the first to analyze the expression of MDR-associated genes sequentially during ILP of patients and demonstrates that treatment might lead to increased levels of MVP, whereas enhanced levels of MDR1 and MRP1 remain rare events.