Antitumor Activity of Ligustilide Against Ehrlich Solid Carcinoma in Rats via Inhibition of Proliferation and Activation of Autophagy.

Abstract

Background Cancer is the second-leading cause of death worldwide. According to a 2018 WHO report, 9.6 million deaths occurred globally due to cancer. Ehrlich carcinoma is characterized by rapid proliferation and a short survival time. Ligustilide is a phthalide derivative and is one of the main compounds in Danggui essential oil and Rhizoma Chuanxiong. It has many protective effects, such as anticancer, anti-inflammatory, antioxidant, and neuroprotective effects. Aims We conducted this study to investigate the antitumor activity of ligustilide against Ehrlich solid carcinoma (ESC) in rats by affecting beclin 1, mammalian target of rapamycin (mTOR), B-cell lymphoma 2 (BCL2), and 5' AMP-activated protein kinase (AMPK). Materials and methods Twenty rats were intramuscularly implanted in the thigh of the left hind limb with a 200-µL tumor cell suspension in PBS containing 2 × 106 cells. After eight days of inoculation, 10 rats out of the 20 were treated with oral 20 mg/kg ligustilide daily. At the end of the experiment, samples of muscles with ESC were separated. Sections prepared from the muscle samples with ESC were immunohistochemically stained with anti-Ki67 antibodies. Another part of the muscle samples with ESC was used to assess gene expression and protein levels of beclin 1, mTOR, BCL2, and AMPK. Results Treatment of carcinoma rats with ligustilide elevated the mean survival time and reduced tumor volume and weight. Moreover, examination of tumor tissue stained with hematoxylin/eosin showed an infiltrative, highly cell-dense mass supported by a small to moderate amount of fibrovascular stroma and intersected with multifocal myofibril necrosis. Treatment with ligustilide ameliorated all these effects in the carcinoma group without affecting the control group. Finally, treatment with ligustilide significantly decreased the expression of beclin 1, mTOR, and AMPK associated with elevated expression of BCL2. Conclusions Our study aimed to explore the potential chemotherapeutic activity of ligustilide against ESC. We found that ligustilide effectively reduced tumor size and weight, indicating its antineoplastic activity against ESC. We further investigated that ligustilide inhibits cell proliferation by suppressing Ki67 and mTOR and activates autophagy through beclin 1 activation. Moreover, ligustilide inhibits apoptosis by upregulating BCL2. Finally, ligustilide reduced the expression of AMPK, preventing its ability to promote tumor cell growth.