Chelerythrine (CHE) is a type of benzophenanthridine alkaloid found in many herbs and is also the main alkaloid constituent of Toddalia asiatica (L.) LAM. It has been proven to have various activities including antitumor, antifungal, anti-inflammatory and anti-parasitic effects. We have previously demonstrated that CHE can inhibit proliferation and promote apoptosis in human hepatocellular carcinoma (HCC) cells. However, the effect of CHE on the metastasis of HCC and its related molecular mechanisms have yet to be validated. In this study, we investigated the effects of CHE on the migration and invasion of the HCC cell line Hep3B. Key words Chelerythrine; hepatocellular carcinoma; metastasis Despite the groundbreaking progress in the diagnosis and treatment of malignant tumors, cancer remains the greatest health concern in the world due to high morbidity and mortality.1) Hepatocellular carcinoma (HCC) is one of the most common types of cancer and the second leading cause of cancer-related death with the 5th highest morbidity rate according to recent studies.2,3) Currently, there are a few treatment options of HCC, including surgical resection and liver transplantation. However, most of the patients who undergo the treatments mentioned above experience new tumors in the residual liver, and their five-year survival rate is no more than 10%.4-6) Metastasis and recurrence are the two main reasons for poor prognosis in patients with HCC. 7) Therefore, key efforts should be focused on blocking invasion and migration of cancer cells.Natural products have been used to treat cancer for over 40 years. Approximately 60% of the clinically used anti-cancer drugs are natural products or derivatives.8) The traditional Chinese medicinal herb Toddalia asiatica LAM. is a kind of traditional folk medicine commonly used in southwest China. It can disperse pathogenic wind and relieve pain, remove blood stasis to stop bleeding, clear away toxic materials and alleviate edema, as stated in the Chinese theory of medicine. We extracted total alkaloids from Toddalia asiatica LAM. and observed obvious anti-inflammatory, analgesic and anti-tumor effects. 10,11) CHE has a wide range of biological activities including antimicrobial, antifungal, anti-inflammatory, anti-parasitic and anti-tumor effects. [11][12][13][14] Regarding cancer therapy, we have reported that CHE can inhibit proliferation and promote apoptosis in HepG2 cells.15) However, the effect of CHE on the metastasis of HCC and its related molecular mechanisms are still undefined.Studies have shown that tumor metastasis involves a serious of complex processes. The primary tumor cells proliferate, invade the basement membrane (BM) and enter the blood and lymphatic circulation. Finally, metastases are formed at distal sites, resulting in secondary tumors. 16,17) In the process described above, the degradation of the extracellular matrix (ECM) is key to tumor migration and invasion. Many protein kinases play important roles in the degradation of the ECM, including matrix metalloprote...