Abstract
Background/Aim: Our studies have shown that an avocado extract (D003) selectively inhibits proliferation in premalignant and malignant but not normal primary human oral epithelial cell lines via an ROS-mediated mechanism. Herein, the in vivo anticancer effect of D003 extract and freeze-dried avocado (FA) was determined in the DMBAinitiated hamster cheek pouch (HCP) model. Materials and Methods: Tumors were initiated in hamster oral mucosa with DMBA followed by topical application of D003, FA, or vehicle. Tumor lesions were counted and evaluated histologically, epithelial proliferation was investigated using MTT assays, and ROS levels in HCP were examined using two photon microscopy. Results: D003 significantly inhibited tumorigenesis (tumor number and volume) compared to FA and vehicle, but neither D003 nor FA reversed premalignant changes induced by DMBA. ROS levels that were increased in the mucosa by DMBA treatment were enhanced by D003. D003 significantly reduced proliferation of cells in DMBAinitiated mucosa. Conclusion: Human cell culture and HCP data show that the phytochemicals extracted from avocado exhibit anticancer activity by inhibiting cancer cell proliferation and progression.
Highlights
Epidemiological investigations have suggested that the consumption of fruits and vegetables is associated with a lower risk of many different types of human cancer including oropharyngeal [1,2,3,4,5,6]
Human cell culture and hamster cheek pouch (HCP) data show that the phytochemicals extracted from avocado exhibit anticancer activity by inhibiting cancer cell proliferation and progression
Ibiebele et al [9] has reported that high intakes of n-6 fatty acids from avocado, vegetables and nuts are inversely associated with risk of ovarian cancer, and Jackson et al [10] have found that increased blood levels of oleic acid, another fatty acid, are associated with a reduced incidence of prostate cancer in Jamaica, where avocado is a major source of oleic acid in the diet
Summary
Epidemiological investigations have suggested that the consumption of fruits and vegetables is associated with a lower risk of many different types of human cancer including oropharyngeal [1,2,3,4,5,6]. As summarized in our previous review [7], avocado contains multiple phytochemicals with potential anticancer activity, among which are some aliphatic acetogenins that are structurally related to fatty acids, are rich and relatively special in avocado [8]. Avocado extracts and isolated individual phytochemicals have shown anticancer activity in various types of human cancer cell lines such as oral, breast, and prostate [7,8,11] in which extracts and individual phytochemicals may act by inhibiting cancer cell proliferation and inducing apoptosis. Our previously published studies have shown that aliphatic acetogenins, (2S, 4S)-2, 4-dihydroxyheptadec-16-enyl acetate and (2S, 4S)-2, 4-dihydroxyheptadec-16-ynyl acetate, two components isolated from avocado, inhibit the EGRK/RAF/MEK/ERK1/2 oncogenic pathway [8]. Studies have shown that avocado extracts up-regulate tumor suppressor genes such as p21 and p27, which are well-documented to block progression through the cell cycle, inducing G2/M cell-cycle arrest [12]
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