The effect of miRNAs and MALAT1 related with the prognosis of Her-2 positive breast cancer patients with lymph node metastasis

Background: To analyze and screen the miRNAs associated with lymph node metastasis of breast cancer (BC), and to explore the roles of these miRNAs in the proliferation, invasion and prognosis of BC. Methods: MicroRNAs associated with lymph node metastasis in Her-2 positive BC was screened by TCGA database. The qRT-PCR was used to verify theses 5 miRNAs in 30 cases of Her-2 positive BC with lymph node metastasis of different degree. The tumor tissue samples were divided into non-lymph node metastasis group, ≤ 3 lymph node metastasis group and > 3 lymph node metastasis group. In addition, 10 cases of paracancerous tissues were considered as paracancerous control group. Pearson correlation analysis was used to analysis the relationship of 5 miRNAs and MALAT1 with Her-2 positive BC patients' clinicopathological characteristics and prognosis. CCK8 and Transwell experiments were used to detect the effects of miR-143 and miR-455 on the proliferation and invasion of Her-2 positive BC cells (MDA-MB-453). Results: Five kinds of miRNA (miR-143, miR-196a, miR-455, miR-9 and miR-92a) related with Her-2 positive BC with lymph node metastasis were screened by TCGA database. The detecting results of qRT-PCR showed that the levels of miR-143, miR-196a, miR-9 and MALAT1 increased with the increased number of lymph nodes. The expression level of miR-143 in the group of ≤ 3 lymph nodes metastasis and > 3 lymph nodes metastasis was significantly higher than that in the group of non-lymph nodes metastasis (P<0.001), and that in the group of > 3 lymph nodes metastasis was significantly higher than that in the group of ≤ 3 lymph nodes metastasis (P<0.001). The expression level of miR-196a in the group of ≤ 3 lymph nodes metastasis and > 3 lymph nodes metastasis was significantly higher than that in the group of non-lymph nodes metastasis (P<0.001), and that in the group of > 3 lymph nodes metastasis was significantly higher than that in the group of ≤ 3 lymph nodes metastasis (P<0.001). The expression level of miR-455 in the group of ≤ 3 lymph nodes metastasis and > 3 lymph nodes metastasis was significantly lower than that in the group of non-lymph nodes metastasis (P<0.001), and that in the group of > 3 lymph nodes metastasis was significantly lower than that in the group of ≤ 3 lymph nodes metastasis (P<0.001). The expression level of MALAT1 in the group of ≤ 3 lymph nodes metastasis and > 3 lymph nodes metastasis was significantly higher than that in the group of non-lymph nodes metastasis (P<0.001), and that in the group of > 3 lymph nodes metastasis was significantly higher than that in the group of ≤ 3 lymph nodes metastasis (P<0.01). Pearson correlation analysis showed that the expression levels of miR-455-5p, miR-196a-5p and MALAT1 were negatively correlated, positively correlated and positively correlated with the pathological stages of Her-2 positive BC, respectively. The results of survival analysis showed that RFS of patients with high expression of miR-196a, miR-92a and MALAT1 was significantly lower than that of patients with low expression (P<0.05), and OS and RFS of patients with high expression of miR-9 were significantly lower than those of patients with low expression, while OS and RFS of patients with high expression of miR-455 were significantly higher than those of patients with low expression (P<0.05). Cytological experiments showed that up regulation of miR-455 significantly inhibited the proliferation and invasion of BC cells, while down regulation of miR-143 significantly inhibited the proliferation and invasion of BC cells and the expression of MALAT1 (P<0.05). Conclusion: High expression of miR-143, miR-9, miR-196a, MALAT1 and low expression of miR-455 are related to the degree of lymph node metastasis of Her-2-positive BC patients, indicating poor prognosis. Down-regulation of miR-455 and up-regulation of miR-143 and MALAT1 can promote the cell proliferation and invasion of Her-2-positive BC.