Wheat-grain moxibustion combined with chemotherapy inhibits tumor growth by suppressing PI3K/AKT/mTOR signaling pathway in breast cancer mice

To observe the effect of wheat-grain moxibustion plus chemotherapy on the activities of phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling and expressions of Caspase-3 and Caspase-9 in mice with breast cancer, so as to explore its mechanisms underlying suppression of tumor growth.

Forty female BALB/c mice were randomly divided into blank control, model, chemotherapy, wheat-grain moxibustion (moxibustion) and moxibustion+chemotherapy groups, with 8 mice in each group. The breast cancer model was established by injection of 4T1 cell suspension (0.1 mL) into the subcutaneous fat pad of the mouse’s right fourth nipple. After successful modeling, the mice of the chemotherapy group and moxibustion+chemotherapy group received injection of Adriamycin (2.5 mg/kg) into the mouse’ leg or abdomen in the morning of Monday and Friday every week, 3 weeks altogether. For mice of the moxibustion and moxibustion+chemotherapy groups, wheat-grain moxibustion was applied to “Shenque” (CV8) and bilateral “Zusanli” (ST36) for 2 cones every time, once every other day for 21 days. The body weight, tumor weight and tumor volume were measured. The histopathological changes of the tumor were observed after H. E. staining. The terminal-deoxynucleoitidyl transferase mediated nick end labeling (TUNEL) was used to detect the apoptosis of tumor tissues in each group. The expression levels of PI3K, AKT, mTOR, phosphorylated (p)-PI3K, p-AKT, p-mTOR, Caspase-3, Cleaved Caspase-3, Caspase-9, and Cleaved Caspase-9 proteins in the tumor tissues were determined by Western blot.

Compared with the model group, the body weight in the chemotherapy group, the tumor weight, tumor volume, and the expression ratios of p-PI3K/PI3K, p-AKT/AKT and p-mTOR/mTOR in the chemotherapy, moxibustion and moxibustion+chemotherapy groups were significantly decreased (P＜0.05), while the apoptosis rate of tumor tissue, the expression levels of Caspase-3, cleaved Caspase-3, Caspase-9 and cleaved Caspase-9 proteins in the chemotherapy, moxibustion and moxibustion+chemotherapy groups were considerably increased (P＜0.05). The therapeutic effect of moxibustion + chemotherapy was significantly superior to that of simple chemotherapy and simple moxibustion in reducing the tumor volume and tumor mass, and in down-regulating the expression ratio of p-AKT/AKT (P＜0.05), and in up-regulating the apoptosis rate and the expression levels of Caspase-3 and cleaved Caspase-3 proteins (P＜0.05), and superior to that of simple moxibustion (not the simple chemotherapy) in up-regulating the expression levels of Caspase-9 and cleaved Caspase 9 protein (P＜0.05). The therapeutic effect of simple moxibustion was evidently inferior to that of simple chemotherapy in reducing tumor volume and tumor mass, in down-regulating the expression ratios of p-PI3K/PI3K and p-mTOR/mTOR (P＜0.05), and in increasing the apoptosis rate, and expression of Caspase-3, Caspase-9 and cleaved Caspase-9 proteins (P＜0.05). H. E. staining showed that the tumor cells of tumor tissue grew diffusely and arranged densely in the model group, while in the chemotherapy, moxibustion and moxibustion+chemotherapy groups, the tumor tissue showed light staining of cytoplasm and nucleus, reduced nuclear division, nuclear debris, smaller density, and different degrees of tumor cell necrosis, and the degree of necrosis was increased in the moxibustion group, chemotherapy group and moxibustion+ chemotherapy group.

Moxibustion plus chemotherapy and simple moxibustion can inhibit tumor growth in breast cancer mice, which may be related to their functions in inhibiting the expression and phosphorylation of PI3K/AKT/mTOR signaling pathway related proteins in the tumor tissue, and then upregulating the expression of apoptosis related proteins Caspase-3 and Caspase-9.