Antitumor effect of traditional Chinese herbal medicines against lung cancer

Traditional Chinese herbal medicine (TCHM) is used widely alone or in combination with chemotherapy to treat lung cancer in China. Meta-analysis of clinical trials of TCHM against lung cancer suggested the potential, but not confirmed therapeutic effect. To gain detailed insight into the antilung cancer effects of TCHM, we searched for preclinical studies of TCHM against lung cancer published from 1995 to 2012 and systematically analyzed published articles focusing on the antitumor effect of individual TCHM in lung cancer cell lines or animal models. Among 93 herbal components isolated from 73 Chinese herbs, we found 10 herbal compounds that showed the strongest cytotoxicity in lung cancer cell lines through apoptosis or cell cycle arrest, and agents isolated from seven Chinese herbs that inhibited the primary tumor growth more than 35% in A549 xenografted mice models. In addition, three herbal components suppressed lung cancer cell migration in vitro at the concentration without cytotoxicity. Polyphyllin I, tanshinone IIA, isochaihulactone, 25-OCH3-PPD, and andrographolide were the five TCHM compounds that showed strong antilung cancer effects both in cells and in animal models, and studies of their analogs showed their structure-activity relationships. This review summarizes and analyzes contemporary studies on the antitumor effect of individual TCHM against lung cancer and animal models, providing perspectives to better understand the TCHM effect in lung cancer treatment and develop new antilung cancer drugs from TCHM.