Abstract
Non-muscle-invasive bladder cancer (NMIBC) has one of the highest recurrence rates among all solid cancers and the highest lifetime treatment cost per patient. Therefore, the development of chemoprevention strategies for reducing the occurrence and recurrence of NMIBC as well as its burdens on the healthcare system is valuable. Our aim was to determine whether flavokawain A (FKA), a kava chalcone isolated from the kava plant, can target the in vivo activated Ha-ras pathway for prevention and treatment of NMIBC. UPII-mutant Ha-ras transgenic mice that develop papillary urothelial cell carcinoma were fed orally with vehicle control or FKA-formulated food for 6 months starting at 6 weeks of age. Seventy-nine percent (15/19) of male mice fed with 6 g FKA per kilogram (kg) of food survived beyond the 6 months of treatment, while 31.6% (6/19) of control food-fed male mice survived the 6-month treatment period (p = 0.02). The mean bladder weights in FKA vs. control food-fed mice were 0.216 ± 0.033 vs. 0.342 ± 0.039 g in male mice (p = 0.0413) and 0.043 ± 0.004 vs. 0.073 ± 0.004 g in female mice (p < 0.0001); FKA reduced bladder weight by 37% and 41%, respectively. The tumor burdens, determined by the wet bladder weight, in these mice were inversely related to plasma FKA concentrations. In addition to decreased bladder weight, FKA treatment significantly reduced the incidences of hydronephrosis and hematuria. FKA-treated mice exhibited more well-differentiated tumors in the bladder and ureter. Immunohistochemical analysis of FKA-treated tumors compared to those in the control group revealed fewer Ki-67- and survivin-positive cells and an increased number of p27- and TUNEL-positive cells, indicating that FKA inhibits proliferation and induces apoptosis. Overall, the results suggest that FKA can target the in vivo activated Ha-ras pathway for the prevention and treatment of NMIBC.
Highlights
Introduction published maps and institutional affilBladder cancer is the fourth most common cancer in men and the twelfth most common in women in the United States [1]
The results suggest that flavokawain A (FKA) can target the in vivo activated Ha-ras pathway for the prevention and treatment of non-muscle-invasive bladder cancer (NMIBC)
We have previously shown that FKA, a predominant chalcone isolated from the kava plant root, is a potent apoptosis inducer against the growth of human urinary bladder cancer cell lines, and preferentially inhibits the growth of p53 mutant cancer cells [10]
Summary
All mice were bred and genotyped as described in our previous publication [6,13]. In brief, heterozygous UPII-mutant Ha-ras+/− females were cross-bred with heterozygous. Homozygous mice with a 1:1 ratio of the transgene to the endogenous UPII gene which had hyperactivation of the Ha-ras oncogene and developed full-blown tumors represented 100% of the mice that were selected for the proposed experiments. Six-week-old, homozygous UPII-mutant Ha-ras transgenic mice were fed with vehicle control or with a 0.6% FKA (0.6% FKA (w/w) in AIN-93M purified) formulated diet for 6 months or until their death. Age-matched nontransgenic mice were administered either the control or the 0.6% FKA diet for the same durations to serve as overall controls. These mice were randomly assigned into different experiment groups with a comparable initial body weight in each group. Animal care and treatments were in accordance with Institutional guidelines and the approved protocol by UCI (protocol #:2004-2540)
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