The aqueous extracts of the leaves and fruit of Camptotheca acuminata have long been used in
traditional Chinese medicine (TCM) for treating
cancer patients. The chemotherapeutic drug,
camptothecin (
CPT), and related analogs were first isolated from C. acuminata in the 1970s. Although the antitumor effects of
CPT have been characterized in recent years, the antitumor effects of aqueous extracts of C. acuminata have not been clarified. The aims of our current study were to determine the
tumor-suppression efficiency of an aqueous extract of the fruit of C. acuminata (AE-CA) in the human
endometrial carcinoma cell lines, HEC-1A, HEC-1B, and KLE, and compare its antitumor effects with those of
CPT. Cell viability assays indicated that a dosage of AE-CA containing 0.28 mg/mL of
CPT demonstrated enhanced cytotoxicity, compared with
CPT treatment. The effects of AE-CA on the induction of cell cycle arrest, the accumulation of cyclin-A2 and -B1, and the activation of
caspase-3 and
caspase-7 were similar to those of
CPT. Furthermore, AE-CA exhibited a synergistic effect on the cytotoxicity of
cisplatin in HEC-1A and HEC-1B cells. These results indicated that AE-CA is a potent
antitumor agent and can be combined with
cisplatin for the treatment of human
endometrial cancer.