| Objectives:This research was to investigate the expressions of multidrug resistance gene 1(MDR1) and coactivator-associated arginine methyltransferase 1(CARM1) in breast cancer, and to explore their relationships with clinicopathological characteristics including tumour size, tumour grade, lymphatic metastases and distant metastases. Meanwhile, this research was to analyze the relationships between CARM1 expression and common breast cancer biomarkers such as estrogen receptor(ER), progesterone receptor(PR), Ki-67 index and human epidermal growth factor receptor type 2(HER2), and to discuss the correlations between CARM1 expression and MDR1 expression, CARM1 expression and different breast cancer subtype. The whole research was in order to support guide new therapeutic and prognostic modalities.Methods:Eighty untreated primary breast tumor samples were collected and prepared for tissue array. CARM1 and MDR1 expression were investigated using immunohistochemistry. CARM1 expression’s relationships with MDR1 expression, ER, PR, HER2 and Ki-67 index were analyzed. The CARM1 and MDR1 expression’s correlations with the prognosis of breast cancer patients were determined by Kaplan-Meier analysis.Results:1. The expression of MDR1 in breast cancer tissues was 57.5%, which was significantly stronger than 31.3% in precancerous tissues. Positive associations were identified between MDR1 expression in breast cancer and tumour size, tumour grade, lymphatic metastases and distant metastases(p<0.05). No association was found between MDR1 and age at diagnosis of breast cancer(p>0.05).2. The expression of CARM1 in breast cancer tissues was 61.3%, which was significantly stronger than 27.5% precancerous tissues. Positive associations were identified between CARM1 expression in breast cancer and tumour size, tumour grade, lymphatic metastases and distant metastases(p<0.05). No association was found between CARM1 and age at diagnosis of breast cancer(p>0.05).3. The expression of CARM1 was significantly different among different molecular subtypes(p<0.05). In the HER2 subtype, the expression of CARM1 was the highest(83.3%), followed by the luminal B subtype(65.0%) and basal subtype(70.5%). The luminal A subtype showed the lowest expression of CARM1(40.0%).4. In MDR1 positive breast cancer tissues, the expression of CARM1 was 71.7%, while the expression of CARM1 was down to 47.1% in MDR1 negative breast cancer tissues. Significantly difference was among them(p<0.05).5. The overall 10-year survival rate of MDR1 positive breast cancer patients was 41.2%, which was significantly lower than 88.6% of MDR1 negative breast cancer patients. The overall 10-year survival rate of CARM1 positive breast cancer patients was 43.3%, which was significantly lower than 83.3% of CARM1 negative breast cancer patients. Significantly differences were among these groups(p<0.05).Conclusions:1. Both of MDR1 expression and CARM1 expression in breast cancer tissues are stronger than that in matched benign precancerous tissues.2. The expressions of MDR1 and CARM1 in breast cance are positive associated with tumour size, tumour grade, lymphatic metastases and distant metastases, which indicated that the expressions of them are significantly associated with the malignant degree and prognostic of breast cancer.3. The expression of CARM1 is significantly different among different molecular subtypes(p<0.05). These indicate that breast cancer is heterogeneous, and presented new subjects for classification of breast cancer.4. In MDR1 positive breast cancer tissues, the expression of CARM1 rate is significantly higher than that of in MDR1 negative breast cancer tissues. These indicate that CARM1 expression has some effects on the regulation of MDR1 expression.5. Both of the overall survival rates of MDR1 positive breast cancer patients and CARM1 positive breast cancer patients are significantly lower than MDR1 and CARM1 negative groups. These indicate that the positive expressions of MDR1 and CARM1 are associated with poor prognosis. |
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