Detection of MRP1 mRNA in human tumors and tumor cell lines by in situ RT-PCR

The detection of the multridrug resistance-associated proteins is becoming increasingly important in assessing tumor sensitivity to treatment. In this work we describe a new, rapid, sensitive, and robust method for the detect ion of MRP1 expression based on direct RT-in situ-PCR technology and fluoro chrome-modified (dCTP(Cy3)) nucleotides. MRP1 expression was found in both placenta (BeWo) and liver (Hep Ga) derived tumor cell line as well as in sm all cell lung carcinoma. In liver-derived cells, MRP1 expression was detect ed by RT-in situ-PCR but not by in situ hybridization, suggesting a higher sensitivity of in situ amplification for the low level of expression in Hep G2 cells. RT solution PCR confirmed the presence of MRP1 in BeWo and Hep G 2 cells, although the level of the gene expression was lower in liver cells . This method represents a viable alternative to conventional immunohistoch emistry, and may be useful in the evaluation of MRP1 expression in differen t tissue or cell lines. (C) 2000 Academic Press.