Objective: To investigate the role of the improved MTT assay in prediction of intrinsic drug resistance of liver cancer.
Methods: The convenient MTT colorimetry was innovated to test the effects of 4'-epi-adriamycin (E-ADM), carboplatin (CBP), and 5-Fluorouracil(5-Fu), used alone or in combination, on 30 specimens of primary liver cancer without chemotherapy. All of the 30 paraffin-embedded tissues were assembled in a microarray. The used terminal concentrations of drugs were one twentieth those of the plasma peak concentrations calculated by using the liver cancer cells of the line SMMC-7721. The expression of P-glycoprotein (P-gp), multidrug resistant protein (MRP)-3, lung resistance-related protein (LRP), glutathione S-transferase (GST)-pi, and 2 kinds of cyclin-related protein: p16(INK4a) and p21WAF1, were detected by immunohistochemistry.
Results: Sixteen of the 30 specimens (53.3%) were drug-resistant and 14 of the 30 specimens (46.7%) were drug-sensitive. The sequence of drug -sensitivity was in the order of combination chemotherapy, E-ADM, 5-Fu, and CBP. The positive rate of P-gp in the drug-resistant group was 56.3%, significantly higher than that of the drug-sensitive group (14.3%, P < 0.05).
Conclusion: An improved MTT assay has been developed that is more scientific and worth spreading clinically. Intrinsic drug resistance of liver cancer is popular. P-gp is a good predictive marker in intrinsic drug resistance of liver cancer.