ABSTRACT
Triple-negative breast cancer (TNBC) is a nasty disease with extremely high malignancy and poor prognosis. Annexin A3 (ANXA3) is a potential prognosis biomarker, displaying an excellent correlation of ANXA3 overexpression with patients' poor prognosis. Silencing the expression of ANXA3 effectively inhibits the proliferation and metastasis of TNBC, suggesting that ANXA3 can be a promising therapeutic target to treat TNBC. Herein, we report a first-in-class ANXA3-targeted small molecule (R)-SL18, which demonstrated excellent anti-proliferative and anti-invasive activities to TNBC cells. (R)-SL18 directly bound to ANXA3 and increased its ubiquitination, thereby inducing ANXA3 degradation with moderate family selectivity. Importantly, (R)-SL18 showed a safe and effective therapeutic potency in a high ANXA3-expressing TNBC patient-derived xenograft model. Furthermore, (R)-SL18 could reduce the β-catenin level, and accordingly inhibit the Wnt/β-catenin signaling pathway in TNBC cells. Collectively, our data suggested that targeting degradation of ANXA3 by (R)-SL18 possesses the potential to treat TNBC.
ABSTRACT
BACKGROUND:5-Fluorouracil is a common chemotherapy drug for gastric cancer, but it is more likely to develop drug resistance in clinical treatment. Studies have shown that tumor stem cels are lowly sensitive to chemotherapeutic drugs, which may be an important cause of chemotherapy resistance. OBJECTIVE:To analyze the sensitivity of gastric cancer stem cels to 5-fluorouracil in vitro, and to understand the mechanism of drug resistance associated with gastric cancer. METHODS:Based on the sorting strategy, human gastric cancer cel clones were isolated from AGS cel lines. CD44 and thymidylate synthetase expression in different clones was detected using immunocytochemistry analysis. Clone formation assay was used to evaluate self-renewal capacity of different clones. Cel counting kit-8 was used to determine the clonal growth inhibition rate of AGS under treatment with different concentrations of 5-fluorouracil. RESULTS AND CONCLUSION:The AGS cels that were inoculated with low density and cultured could differentiate into 32 forms, including the ful clone (16%, 5/32), the second clone (66%, 21/32) and the accessory clone (19%, 6/32). Among them, the ful clones highly expressed CD44 and thymidylate synthetase, and could generate a great amount of passage 2 clones after inoculation; the second clones showed a weak expression of CD44 and thymidylate synthetase, and could generate a smal number of passage 2 clones after inoculation; the accessory clones showed a weak or no expression of CD44 and thymidylate synthetase, and there was no passage 2 clone after inoculation. Under the effect of different concentrations of 5-fluorouracil, the growth inhibition rates of the secondary clones and AGS cels were both higher than that of the ful clones (bothP < 0.05). These findings indicate that gastric cancer stem cels have a relatively lower sensitivity to 5-fluorouracilin vitro, which is speculated to be an important mechanism of drug resistance.