Anti-Proliferative Activity and Cytotoxicity of Solanum Jamesii Tuber Extracts in Human Colon and Prostate Cancer Cells In Vitro

Authors: NZARAMBA, M - Texas A&M University; REDDIVARI, L - Texas A&M University; Bamberg, John; MILLER, J - Texas A&M University

Submitted to: Journal of Agriculture and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/2/2009
Publication Date: 8/27/2009
Citation: Nzaramba, M.N., Reddivari, L., Bamberg, J.B., Miller, J.C. 2009. Anti-Proliferative Activity and Cytotoxicity of Solanum Jamesii Tuber Extracts in Human Colon and Prostate Cancer Cells In Vitro. Journal of Agriculture and Food Chemistry. 57:8308-8315.

Interpretive Summary: Wild potato has been shown to have nutritive compounds, including those that inhibit cancer cell cultures. When the juice of one such species, Solanum jamesii, known to be very high in antioxidants, was tested for its effect on these cancer cell cultures, a great variation was observed. Tuber juice of some populations of this species quickly and markedly suppressed prostate cancer growth even at low doses, while others did not. This preliminary study shows us how to set up more focused future experiments that will identify the best materials for breeding, and will also provide potato scientists with clues for better understanding (and manipulating) the underlying genetic and physiological mechanisms. Prostate cancer is the most common cancer of men in the U.S. and the second leading cause of cancer death, with healthcare cost of just the new U.S. victims equaling $2.4B each year. The high per capita consumption of potato makes it a powerful delivery mechanism for anti-cancer nutrients. Thus, studies that lead to this type of potato nutritional improvement could provide huge returns in reduced suffering and healthcare costs.

Technical Abstract: Some tuber-bearing wild potato species are reportedly higher in health-promoting traits such as antioxidant activity (AOA) and total phenolic content (TP) than commercial cultivars; therefore, they could be used as parental material in breeding for high AOA and TP. However, using wild species might result in progenies that are toxic for human consumption due to presence of high total glycoalkaloids (TGA) and other unknown compounds. Therefore, wild potato accessions should be screened for cytotoxicity before their introduction in breeding programs. The objective of this study was to investigate anti-proliferative activity and cytotoxicity of tuber extracts from 15 Solanum jamesii accessions on human HT-29 colon and LNCaP prostate cancer cell lines in vitro. Also, correlations among AOA, TP, TGA, and anti-cancer cell proliferation were determined. The tuber extracts significantly inhibited proliferation of HT-29 and LNCaP cell lines and were not cytotoxic to the cells compared to the control (DMSO). The anti-proliferative activity exhibited by tuber extracts was not due to necrosis, because the amount of LDH released from cells incubated with the extracts was not significantly different from that released from cells incubated without extracts (control). Colon cancer cells were more responsive to tuber extract treatment than prostate cancer cells. In both HT-29 and LNCaP cells, there were no observable significant correlations between antioxidant activity (DPPH and ABTS) and inhibition of cell proliferation, or between TP and cell proliferation inhibition. Also, glycoalkaloids did not exhibit significant correlations with inhibition of cancer cell proliferation. Findings of this study show that S. jamesii accessions probably pose no health problems when used as parental material in improving the nutritional value of potato cultivars. Correlation results, together with cell proliferation data, suggest that compounds other than those evaluated may be contributing to the anti-proliferative effects of potato tuber extracts.