The significance of expression of autophagy-related gene Beclin, Bcl-2, and Bax in breast cancer tissues

Abstract

The purpose of this study was to detect the expression of autophagy-related gene Beclin1 and apoptosis-related genes Bcl-2 and Bax in breast cancer tissues, to investigate their relationship and significance to the occurrence and development of breast cancer, and to provide an experimental basis for the biological treatment of breast cancer in the future. Human breast cancer tissues and relatively healthy breast tissue adjacent to the tumor were collected during surgical resection. By using RT-PCR and western blot, the mRNA and protein expressions of Beclin1, Bcl-2, and Bax were detected in the breast cancer tissues and the relatively healthy, adjacent tissues. The correlations of these expressions with the occurrence, development, and clinicopathology of breast cancer were analyzed. The mRNA and protein expressions of Beclin1 and Bcl-2 in breast cancer tissues were significantly lower than those in the relatively healthy, adjacent breast tissues (p < 0.05); the lower the degree of tumor differentiation, the lower the mRNA and protein expressions of Beclin1 and Bcl-2 (p < 0.05); the mRNA and protein expressions of Beclin1 and Bcl-2 in breast cancer tissues from patients positive for lymph node metastasis were significantly lower than those negative for lymph node metastasis (p < 0.05); the mRNA and protein expressions of Beclin1 and Bcl-2 in breast cancer tissues from patients positive for distant metastasis were significantly lower than those negative for distant metastasis (p < 0.05); the mRNA and protein expressions of Beclin1 and Bcl-2 in breast cancer tissues from patients positive for ki67 were significantly lower than those negative for ki67 (p < 0.05). The mRNA and protein expressions of Bax were different from those of Beclin1 and Bcl-2. In breast cancer tissues, the mRNA and protein expressions of Bax were up-regulated (p < 0.05); the lower the degree of tumor differentiation, the higher the mRNA and protein expressions of Bax (p < 0.05); the mRNA and protein expressions of Bax in breast cancer tissues from patients positive for lymph node metastasis were significantly higher than those negative for lymph node metastasis (p < 0.05); and the mRNA and protein expressions of Bax in breast cancer tissues from patients positive for distant metastasis were significantly higher than those in patients negative for distant metastasis (p < 0.05). However, the mRNA and protein expressions of these three genes were not correlated with patient age, tumor size, progesterone receptor positivity, or human epidermal growth factor positivity (p > 0.05). The correlation of Bcl-2 and Bax mRNA with Beclin1 mRNA expressed in breast cancer tissues were both statistically significant (p < 0.05). The activity change of autophagy and apoptosis is associated with the tumorigenesis and tumor progression of breast cancer. The joint detection of these three genes (Beclin1, Bcl-2, and Bax) contributes to the early diagnosis of and predicts prognosis for breast cancer, and this also provides an experimental basis for the biological therapy of breast cancer.