Correlation between multidrug resistance and the degree of differentiation of non-small-cell bronchopulmonary carcinoma (NSCLC) in vitro and in vivo.

The correlation between the degree of expression of the multidrug resistance-1 (MDR-1) gene and the process of differentiation into non-small-cell, bronchopulmonary carcinoma was studied in vitro and in vivo. For this purpose, a technique for the quantitative analysis of MDR-1 gene expression was developed by competitive reverse-transcriptase polymerase chain reaction. The study of 9 epidermoid carcinomas with various degrees of differentiation did not enable us to establish a correlation in vivo in the patient. However, an in vitro study performed on a non-small-cell lung carcinoma cell line and two of its clones showed that MDR-1 gene expression increased with the degree of differentiation, which was confirmed in vivo when this line was xenografted into nude mice.