BACKGROUND & OBJECTIVE: It is still unclear whether overexpression of mdr-1 gene play a role in the chemotherapy resistance of lymphoma. This study was designed to investigate P-glycoprotein(P-gp) and mdr-1 mRNA levels of lymphoma and to observed the impact of P-gp level upon chemotherapy response. METHODS: Ten samples of relapsed lymphoma and 21 samples of untreated lymphoma were assessed by flow cytometry(FCM). The mdr-1 mRNA levels were determined by real-time reverse-transcription PCR assay simultaneously in eighteen samples. The impact of P-gp levels upon chemotherapy response was observed in seventeen patients. RESULTS: Nineteen Percent (4/21) patients overexpressed P-gp at diagnosis as compared to 60%(6/10) in relapse(P = 0.012). The copy numbers of mdr-1 mRNA were 4 x 10(2)-1.32 x 10(4) copies/microgram RNA in untreated group and 4 x 10(2)-4 x 10(4) copies/microgram RNA in recurrent group. There existed significant difference in the distribution of mdr-1 mRNA expression between these two groups, P < 0.05. The complete response rates were 46% (6/13) in P-gp non-overexpression group and 25% (1/4) in P-gp overexpression group(P = 0.60). CONCLUSION: Relapsed lymphomas highly express P-gp and mdr-1 mRNA. The overexpression of mdr-1 gene may play a role in the multidrug resistance of relapsed lymphoma.
BACKGROUND & OBJECTIVE: It is still unclear whether overexpression of mdr-1 gene play a role in the chemotherapy resistance of lymphoma. This study was designed to investigate P-glycoprotein(P-gp) and mdr-1 mRNA levels of lymphoma and to observed the impact of P-gp level upon chemotherapy response. METHODS: Ten samples of relapsed lymphoma and 21 samples of untreated lymphoma were assessed by flow cytometry(FCM). The mdr-1 mRNA levels were determined by real-time reverse-transcription PCR assay simultaneously in eighteen samples. The impact of P-gp levels upon chemotherapy response was observed in seventeen patients. RESULTS: Nineteen Percent (4/21) patients overexpressed P-gp at diagnosis as compared to 60%(6/10) in relapse(P = 0.012). The copy numbers of mdr-1 mRNA were 4 x 10(2)-1.32 x 10(4) copies/microgram RNA in untreated group and 4 x 10(2)-4 x 10(4) copies/microgram RNA in recurrent group. There existed significant difference in the distribution of mdr-1 mRNA expression between these two groups, P < 0.05. The complete response rates were 46% (6/13) in P-gp non-overexpression group and 25% (1/4) in P-gp overexpression group(P = 0.60). CONCLUSION: Relapsed lymphomas highly express P-gp and mdr-1 mRNA. The overexpression of mdr-1 gene may play a role in the multidrug resistance of relapsed lymphoma.