Study on the Antitumor Effect of Huanglian Decoction Combined with Radiation on Mice with Lewis Lung Cancer

OBJECTIVE To study the antitumor effect and mechanism of Huanglian decoction combined with X-ray radiation on mice with Lewis lung cancer.

METHODS The 60 SPF grade male C57BL/6 mice were randomly divided into blank group, model group, radiation group, radiation combined with Huanglian decoction low dose, medium dose and high dose groups, with 10 mice in each group. In addition to the blank group, Lewis cells were injected into the right armpit of mice in all other groups to construct a lung cancer tumor bearing mouse model. After model successfully established, the tumor site was irradiated locally with 4 Gy X-ray in each radiation group. After irradiation, the radiation combined with Huanglian decoction low dose, medium dose and high dose groups were given 0.2 mL·d⁻¹ of Huanglian decoction by gavage at doses of 5.78, 11.57 and 23.14 g·kg⁻¹, respectively, whereas those in the blank, model and radiation group were given equal volume of normal saline. After continuous intervention for 7 d, the mice were killed and tumor tissue samples were collected. HE staining was used to observe the histopathological changes of tumor. The expression of Ki67 in tumor tissues was detected by immunohistochemistry. The apoptosis of tumor cells was detected by immunofluorescence. qRT-PCR was used to detect the expression levels of EGFR and HIF-1α mRNA in tumor tissues. The expression levels of EGFR, HIF-1α, Bcl-2, Bax and Caspase-3 proteins in tumor tissues were detected by Western blotting.

RESULTS Compared with the model group, the tumor weight of mice in radiation group was reduced(P<0.05), the tumor cells were arranged loose, the cell gap was blurred, the phenomenon of patchy hemorrhagic necrosis appeared, the apoptotic cells were increased(P<0.01), and the mRNA expression of EGFR and HIF-1α were increased. The protein expressions of EGFR, HIF-1α, Bax, Bcl-2 and Caspase-3 were increased while Ki67 was decreased(P<0.05 or P<0.01). Compared with the radiation group, the tumor weight of mice in the radiation combined with medium dose and high dose groups of Huanglian decoction were decreased(P<0.05 or P<0.01), necrosis were observed in tumor tissues of mice, apoptotic cells were increased significantly(P<0.01), EGFR and HIF-1α mRNA expression decreased, and EGFR, HIF-1α, Bcl-2 and Ki67 protein expression were decreased, while the expression of Bax and Caspase-3 protein were increased(P<0.01).

CONCLUSION Huanglian decoction combined with radiation can effectively inhibit the tumor growth of mice with Lewis lung cancer, and the mechanism may be related to the regulation of EGFR and HIF-1α signaling pathway mediated apoptosis.