Effects of Acanthus ebracteatus Vahl on tumor angiogenesis and on tumor growth in nude mice implanted with cervical cancer

Abstract

Taksanee Mahasiripanth,1 Sanya Hokputsa,2 Somchai Niruthisard,3 Parvapan Bhattarakosol,4 Suthiluk Patumraj51Inter-Department of Physiology, Chulalongkorn University, Bangkok, Thailand; 2Research and Development Institute, Government Pharmaceutical Organization, Bangkok, Thailand; 3Obstetrics and Gynecology Department, 4Department of Microbiology, 5Center of Excellence for Microcirculation, Faculty of Medicine, Chulalongkorn University, Bangkok, ThailandPurpose: The aim of this study was to examine the effects of the crude extract of Acanthus ebracteatus Vahl (AE) on tumor growth and angiogenesis by utilizing a tumor model in which nude mice were implanted with cervical cancer cells containing human papillomavirus 16 DNA (HPV-16 DNA).Materials and methods: The growth-inhibitory effect of AE was investigated in four different cell types: CaSki (HPV-16 positive), HeLa (HPV-18 positive), hepatocellular carcinoma cells (HepG2), and human dermal fibroblast cells (HDFs). The cell viabilities and IC50 values of AE were determined in cells incubated with AE for different lengths of time. To conduct studies in vivo, female BALB/c nude mice (aged 6–7 weeks, weighing 20–25 g) were used. A cervical cancer-derived cell line (CaSki) with integrated HPV-16 DNA was injected subcutaneously (1 × 107 cells/200 µL) in the middle dorsum of each animal (HPV group). One week after injection, mice were fed orally with AE crude extract at either 300 or 3000 mg/kg body weight/day for 14 or 28 days (HPV-AE groups). Tumor microvasculature and capillary vascularity were determined using laser scanning confocal microscopy. Tumor tissue was collected from each mouse to evaluate tumor histology and vascular endothelial growth factor (VEGF) immunostaining.Results: The time-response curves of AE and the dose-dependent effect of AE on growth inhibition were determined. After a 48-hour incubation period, the IC50 of AE in CaSki was discovered to be significantly different from that of HDFs (P < 0.05). A microvascular network was observed around the tumor area in the HPV group on days 21 and 35. Tumor capillary vascularity in the HPV group was significantly increased compared with the control group (P < 0.001). High-dose treatment of AE extract (HPV-3000AE group) significantly attenuated the increase in VEGF expression and tumor angiogenesis in mice that received either the 14- or 28-day treatment period (P < 0.001).Conclusion: Our novel findings demonstrated that AE crude extract could inhibit cervical cancer growth, VEGF expression, and angiogenesis in a CaSki-cell transplant model in mice.Keywords: Acanthus ebracteatus Vahl, tumor angiogenesis, VEGF, CaSki cell-implanted nude mice, capillary vascularity, laser scanning confocal microscopy