[Shengmai San improves osimertinib resistance of non-small cell lung cancer cells by regulating the lactate/Wnt/β-catenin/LDHA pathway].

OBJECTIVES: To explore the effect of Shengmai San (SMS) for improving osimertinib resistance in non-small cell lung cancer cells and the underlying mechanism.

METHODS: Cultured A549 cells were treated with osimertinib alone or in combination with SMS-medicated rat serum, and the changes in cell viability and glucose and lactate levels were determined. The effect of SMS combined with osimertinib for improving osimertinib resistance of A549 cells was assessed in a mouse model bearing subcutaneous A549 cell xenograft. Western blotting, RT-qPCR, and immunofluorescence staining were used to analyze the effects of SMS and lactate on the Wnt/β‑catenin/LDHA signaling pathway.

RESULTS: SMS significantly increased osimertinib sensitivity of A549 cells in a concentration-dependent manner. Compared with osimertinib alone, the combined treatment with SMS and osimertinib significantly inhibited cell viability, colony formation ability, and tumor growth in nude mice. SMS concentration-dependently decreased glucose and lactate levels in A549 cells. The results of Western blotting showed that SM inhibited the protein expression of LDHA, total β‑catenin, and cytoplasmic and nuclear β‑catenin, while lactate obviously activated the expressions of total β‑catenin protein, nuclear β‑catenin, and LDHA in A549 cells. Immunofluorescence concentration-dependent staining showed that lactic acid activated nuclear accumulation of β‑catenin protein, while SMS significantly inhibited the expression of nuclear β‑catenin protein; RT-qPCR demonstrated that lactate significantly increased mRNA expressions of the Wnt/β‑catenin downstream target genes (c-myc, CD44, Axin2, Oct3/4, survivin, and CCND1), while SMS inhibited their expressions.

CONCLUSIONS: SMS improves osimertinib resistance in non-small cell lung cancer cells by inhibiting lactate/Wnt/β-catenin/LDHA pathway-mediated glycolysis.