[Ursolic acid down-regulates ANXA6 and inhibits breast cancer cell growth and metastasis].

Objective: To investigate the mechanism of ursolic acid (UA) in inhibiting the growth and metastasis of breast cancer MDA-MB-231 ("231") cells by downregulating ANXA6. Methods: This study conducted relevant in vitro cytology and molecular biology experiments in the Department of Clinical Laboratory and Central Laboratory of Putuo Hospital, Shanghai University of Traditional Chinese Medicine from February 2023 to August 2024. Human breast cancer 231 cells were cultured in vitro, and the effects of different concentrations of UA on the proliferation and invasion and metastasis of 231 cells were detected by CCK-8 and Transwell assays. Western Blot was used to detect the effect of UA on the expression of ANXA6 and invasion and metastasis-related proteins MMP9, β-catenin and N-cadherin in 231 cells. The 231 cells that interfered with and overexpressed ANXA6 were constructed by lentivirus transfection to generate stable ANXA6 interfering and overexpressing 231 cells, which were divided into 231/KD-ANXA6 group, 231/KD-NC group, 231/OE-ANXA6 group, and 231/OE-NC group. CCK-8 assay and Transwell assay were used to detect the proliferation activity, invasion and metastasis ability of 231 cells after interference and overexpression of ANXA6 and the effect of UA on the proliferation ability of 231 cells after interference and overexpression of ANXA6. Western Blot and RT-PCR assays were used to detect the expression of invasion and migration biomarkers such as MMP9, β-catenin, and N-cadherin in 231 cells after interference and overexpression of ANXA6. Immunohistochemistry was used to detect the expression level of ANXA6 in breast cancer tissues, and the relationship between ANXA6 expression and clinicopathological features and prognosis of breast cancer was analyzed. Results: The CCK-8 assay results showed that compared with the control group (0 μmol/L UA, 100.00%±7.37%), the proliferative activity of 231 cells at UA concentrations of 2.5, 5, 10, 20 and 40 μmol/L (90.23%±1.76%, t=2.24, P<0.05; 85.19%±4.23%, t=3.02, P<0.05; 65.45%±0.35%, t=8.11, P<0.01; 37.79%±0.98%, t=14.50, P<0.001; 18.18%±0.15%, t=19.23, P<0.001) were significantly decreased. Furthermore, UA (10, 15, 20 μmol/L) inhibited the invasion and metastasis ability of 231 cells; Western Blot assay showed that compared with the control group (0 μmol/L UA), the protein expressions of MMP9 (1.07±0.03 vs 0.99±0.11, t=1.27, P>0.05), β-catenin (1.21±0.01 vs 0.99±0.07, t=5.47, P<0.05), N-cadherin (1.05±0.09 vs 0.90±0.03, t=2.65, P>0.05) at UA of 10 μmol/L; MMP9 (1.07±0.03 vs 0.79±0.09, t=5.26, P<0.001), β-catenin (1.21±0.01 vs 0.89±0.05, t=10.55, P<0.001), and N-cadherin (1.04±0.09 vs 0.68±0.10, t=4.59, P<0.05) at UA of 15 μmol/L; MMP9 (1.07±0.03 vs 0.52±0.07, t=12.50, P<0.001), β-catenin (1.21±0.01 vs 0.83±0.02, t=24.01, P<0.000 1) and N-cadherin (1.04±0.09 vs 0.49±0.11, t=6.70, P<0.01) at UA of 20 μmol/L. Interfering with ANXA6 inhibits the proliferation, invasion and migration of 231 cells, and overexpression of ANXA6 promotes the proliferation, invasion and migration of 231 cells. Western Blot assay showed that compared with the control group (KD-NC group), the protein expressions of MMP9 (1.07±0.01 vs 0.62±0.16, t=4.86, P<0.01), β-catenin (1.02±0.14 vs 0.64±0.15, t=3.20, P<0.05), N-cadherin (0.98±0.14 vs 0.67±0.12, t=2.85, P<0.05) were decreased expression; Compared with the control group (OE-NC group), the protein expressions of MMP9 (0.54±0.22 vs 1.06±0.08, t=3.90, P<0.05), β-catenin (0.92±0.07 vs 1.06±0.04, t=3.06, P<0.05) and N-cadherin (0.90±0.07 vs 1.06±0.01, t=3.75, P<0.05) were significantly increased. Interference with ANXA6 promoted the inhibitory effect of UA on the proliferation ability of 231 cells (P<0.05). Overexpression of ANXA6 weakened the inhibitory effect of UA on the proliferation of 231 cells (P<0.05).The results of immunohistochemistry assay showed that the expression level of ANXA6 in breast cancer tissue was significantly increased, and the expression of ANXA6 was related to tumor size (P<0.05), but not to age, T stage, N stage, pathological grade, AJCC stage, ER, PR and E-cad. Conclusion: The expression level of ANXA6 in breast cancer tissues is increased, and UA can inhibit the growth, invasion and metastasis of 231 cells by down-regulating the expression of ANXA6.