Delaying the Hormone Refractory Prostate Cancer by a Dietary Triterpene Lupeol

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DESCRIPTION (provided by applicant): Persistence of cancer cells even after surgery and androgen-ablation therapy, their proliferation, androgen- independence and invasion to distant sites is the major cause of deaths in human prostate cancer patients. Delaying or slowing down the process of prostate cancer cells to become highly aggressive hormone refractory phenotype would lead to the prolongation in the survival, better management and in improvement in the quality of life of prostate cancer patients. Unfortunately, patients with advanced hormone refractory tumors most often fail to respond to or very poorly respond to current conventional cancer therapies. The challenges in the implementation of effective therapeutic strategies for the treatment of advanced hormone refractory prostate cancer reflect the multidimensional nature and functional significance of pro-survival and pro-proliferation signaling pathways in the emergence of therapeutic resistance of prostate tumors. The persistent activation of androgen receptor in hormone refractory prostate cancer cells even under non-androgen conditions has been associated with the activation of PI3K/Akt signaling. The activated PI3K/Akt forms a signaling axis with 2- catenin and NF:B pathways, thus converging on common downstream targets, and ultimately leads to the hormone-refractory, chemoresistant and highly aggressive prostate cancer cells with an ability to migrate and invade heterotopic tissues such as bones and lymph nodes in humans. While a full understanding of the hormone-refractory and pro-survival characteristics of multiple signaling pathways is still evolving, the impact that Akt/ss-catenin/NF:B signaling axis has been widely accepted and there are efforts to utilize these pathways for therapeutic targeting of its key signaling steps. Thus, there is a strong unmet need to develop new therapeutic agents (with an ability to target multiple molecular pathways) which are effective against androgen-independent prostate tumor development as well as the recurrence of disease. We will provide compelling evidence that Lupeol, (a non-nutrient and non-toxic natural agent present in olive, strawberry, grapes, mango, figs and vegetable oils) could be an ideal multi-target agent which could prevent or delay the onset of transition of hormone-dependent to hormone-independent process in human prostate cancer. We hypothesize that Lupeol will prevent /or delay the transformation of hormone-dependent CaP to hormone independent disease through the disruption of Akt/2-catenin/NF:B signaling axis. To achieve our goal, we propose two specific aims. Under the first specific aim, we propose to investigate whether Lupeol (i) prevents or delays the onset of androgen-independence in human CaP cells and (ii) sensitizes the hormone refractory CaP cells for androgen-antagonist treatment under in vitro conditions. Under the second specific aim, we propose to investigate whether Lupeol (iii) alone and in combination with androgen ablation prevents or delays the onset of emergence of androgen-independence of human CaP tumors and (iv) sensitizes the hormone refractory CaP tumors for androgen-antagonist therapy, in an orthotopic xenograft mouse model. We believe that this proposal will be extremely valuable in providing a novel fruit and vegetable based agent for chemoprevention and possibly for treating early as well as advanced prostate cancer. PUBLIC HEALTH RELEVANCE: We believe that this proposal will be extremely valuable in providing a novel fruit and vegetable based agent with a known mechanism of action for delaying or preventing the onset of transition of hormone-dependent prostate cancer to hormone refractory and chemoresistant phenotype. Successful completion of this proposal will establish the potential of Lupeol for the treatment of advanced prostate cancer.