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Expression of mdr1 gene in human breast primary tumors and metastases
E Hennequin1, C Delvincourt, C Pourny
1GIBSA, Laboratoire de Biochemie, Institut Jean Godinot, Reims, France.
Abstract:
Expression of mdr1 gene has been evaluated in 34 tumor samples obtained from breast cancer patients who were classified according to their treatment, and clinical follow-up. No gene amplification was found. mdr1-RNA was never detected in 29 primary breast tumors including 5 samples from patients previously treated by 6 courses of 5-fluorouracil, epirubicin, cyclophosphamide (FEC). On the other hand, mdr1-RNA expression was detected in 1 local recurrence and 2 out of 3 metastases, all of them being treated and exhibiting a poor evolution. A second, untreated local recurrence remained negative. Clinical follow-up for 7 to 48 months in patients receiving chemotherapy showed that absence of mdr1-RNA could not be an accurate factor of satisfactory response to chemotherapy. But, all the patients with detectable mdr1-RNA exhibited a poor evolution and response to treatment. In conclusion, evaluation of mdr1-RNA seemed to be of little interest in primary breast tumors. However, the concomitant presence of an mdr1-RNA and a metastatic phenotype could give a new insight into the relationship between invasive and resistance properties of cancer cells. Such situations would need to be analyzed very carefully for a better utilization of chemotherapy.
Insights
Multidrug resistance gene 1 (mdr1) RNA was rarely found in primary breast tumors but was detected in some recurrent and metastatic cases. mdr1-RNA presence correlated with poor treatment response and disease progression.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Multidrug resistance (MDR) is a significant challenge in cancer chemotherapy.
- The mdr1 gene, encoding P-glycoprotein, is a key mediator of MDR.
- Understanding mdr1 gene expression in breast cancer is crucial for optimizing treatment strategies.
Purpose of the Study:
- To investigate the expression of the mdr1 gene in breast cancer tissues.
- To correlate mdr1 gene expression with treatment status and clinical outcomes.
- To assess the diagnostic and prognostic value of mdr1-RNA in breast cancer.
Main Methods:
- Analysis of mdr1 gene expression (RNA detection) in 34 breast tumor samples.
- Classification of patients based on treatment history and clinical follow-up.
- Evaluation of gene amplification and RNA levels.
Main Results:
- No mdr1 gene amplification was detected in any samples.
- mdr1-RNA was not detected in 29 primary breast tumors, including those treated with FEC chemotherapy.
- mdr1-RNA was detected in 1 local recurrence and 2 of 3 metastases, all with poor outcomes.
- Absence of mdr1-RNA did not predict a satisfactory response to chemotherapy.
- Detectable mdr1-RNA was associated with poor clinical evolution and treatment response.
Conclusions:
- mdr1-RNA evaluation has limited utility in primary breast tumors.
- The presence of mdr1-RNA in metastatic or recurrent breast cancer may indicate invasive and resistant properties.
- Further analysis is needed to understand the role of mdr1-RNA in advanced disease for improved chemotherapy utilization.