Manabu Okano

Detection of Low-level Expression of P-Glycoprotein in ACHN Renal Adenocarcinoma Cells

A highly sensitive reverse transcriptase‐polymerase chain reaction (RT‐PCR) assay and a flow cytometric assay were used to examine ACHN cells for the expression of P‐glycoprotein. The expression of P‐glycoprotein was detected at the RNA and protein levels in ACHN cells by RT‐PCR and flow cytometry, respectively. However, it was below the limit of detection by immunoblotting. The intracellular accumulation of adriamycin in ACHN cells was enhanced by verapamil, cyclosporin A and medroxyprogesterone acetate. Therefore, this study has demonstrated that low‐level expression of P‐glycoprotein detectable only by RT‐PCR and flow cytometry plays a significant role in reducing the intracellular concentration of antitumor agents and thus contributes to the multidrug‐resistant phenotype of ACHN cells.

Immunological comparison between prostate-specific antigen and γ-seminoprotein

SummaryProstate-specific antigen (PA) and γ-seminoprotein (γ-Sm) were compared by immunocytochemical, immunodiffusion and immunoblotting methods using rabbit anti-PA antibody and rabbit anti-γ-Sm antibody. Enzyme immunoassys (EIAs) were developed for measurements of PA and γ-Sm to determine a correlation between serum PA and γ-Sm levels in patients with prostate cancer. The patterns of localization and distribution of PA and γ-Sm were identical in prostate tissue sections, including benign and cancerous human prostacs. The immunodiffusion study showed that the antigens with which anti-PA antibody and anti-γ-Sm antibody reacted in seminal plasma and prostate tissue homogenates were identical to each other. In the immunoblotting study, anti-PA antibody and anti-γ-Sm antibody recognized a single antigen corresponding to a molecular weight of approximately 33,000 both in seminal plasma and prostate tissue homogenates. The EIAs developed in this study were sensitive, specific, and reproducible, and the correlation between serum PA and γ-Sm values determined by these EIAs was highly significant (r=0.99, P(0.001). These results indicated that PA and γ-Sm were immunologically identical and that serum PA and γ-Sm determined by immunoassays using anti-PA antibody and anti-γ-Sm antibody should be evaluated as identical tumor markers for serodiagnosis of prostate cancer.

CORRELATION OF EXPRESSION LEVELS OF P-GLYCOPROTEIN WITH RESISTANCE TO ADRIAMYCIN IN A RENAL ADENOCARCINOMA CELL LINE

We have demonstrated that low-level expression of P-glycoprotein (PGP), detectable by reverse transcriptase-polymerase chain reaction (RT-PCR) assay and flow cytometric assay, is an important factor in multidrug resistance (MDR) in ACHN cancer cells. In this study, we established a subline highly resistant to adriamycin (ACHN/ADM) from ACHN cells, and determined the correlation between PGP levels and MDR levels using ACHN/ADM cells and their parent ACHN cells. The ACHN/ADM cells showed overexpression of PGP, and sensitivity to antitumor agents was lower than that found in ACHN cells. Intracellular accumulation of ADM in ACHN/ADM cells was approximately half the amount of its accumulation in ACHN cells. Sensitivity to ADM in ACHN/ADM cells was enhanced by chemosensitizers with an increase in intracellular ADM accumulation. These results indicate that PGP levels correlate with MDR levels and suggest that chemotherapy using chemosensitizers might be effective in the treatment of renal cancers with overexpression of PGP.