Androgen-withdrawal-induced apoptosis (AWIA) is deregulated in androgen refractory prostate cancer. Androgens have been shown to positively regulate expression of the antiapoptotic FADD-like interleukin-1b-converting enzyme (FLICE)-like inhibitory protein (FLIP), and reduced FLIP expression precedes apoptosis after androgen withdrawal. Here, we show that FLIP protein expression is downregulated in castrated rats, while in LNCaP cells, androgens regulate FLIP in a manner that is dependent on phosphoinositol-3-kinase (PI3K) and Akt signaling. Specifically, treatment of LNCaP cells with LY294002, or expression of either PTEN or a nonphosphorylatable form of FOXO3a (FOXO3aTM), downregulates FLIP protein and mRNA. Conversely, treatment with androgens in the absence of PI3/Akt signaling, or following expression of FOXO3aTM, leads to increased FLIP expression. A FOXO3a binding site was identified in the FLIP promoter and shown necessary for the combined effects of androgens and FOXO3a on FLIP transcription. FOXO3a binds the androgen receptor, suggesting that the transcriptional synergy depends on an interaction between these proteins. Finally, LNCaP cells are sensitized to TRAIL-induced apoptosis by PTEN or LY294002, and rescued by androgens. FOXO3aTM also sensitizes cells to androgen-inhibited TRAIL apoptosis. Androgen rescue was diminished when either FOXO3a or FLIP was reduced by siRNA. These data support a role for FOXO3a in AWIA.
Background: Acute kidney injury (AKI) is associated with a significantly increased risk of morbidity and mortality. Ischemia–reperfusion injury (IRI) is a major cause of AKI. In this study, we investigated the role of the endocannabinoid (EC) system in renal IRI using a well-established mouse model.Materials and Methods: Renal ischemia was induced in male C57BL/6 mice by clamping both kidney pedicles for 30 min followed by 24 h of reperfusion. To increase renal 2-arachidonoylglycerol (2-AG) levels, mice were pretreated with JZL184 (16 mg/kg), 30 min before IRI. Serum creatinine and blood urea nitrogen (BUN), renal tubular damage, renal content of ECs and renal expression of markers of inflammation and oxidative stress were measured.Results: Renal IRI was associated with significantly increased serum BUN and creatinine, increased tubular damage score, increased expression of renal markers of inflammation and oxidative stress and elevated renal 2-AG content. Pretreatment with JZL184 was associated with a significant increase in renal 2-AG content and there was also improved serum BUN, creatinine and tubular damage score. However, renal expression of inflammation and oxidative stress markers remained unchanged.Conclusions: This is the first report documenting that renal IRI is associated with an increase in kidney 2-AG content. Further enhancement of 2-AG levels using JZL184 improved indices of renal function and histology, but did not lower renal expression of markers of inflammation and oxidative stress. Further studies are needed to determine the mechanisms responsible for the effects observed and the potential value of 2-AG as a therapeutic target in renal IRI.
2. Melodelima D, Chapelon JY, Theillere Y, Cathignol D. Combination of thermal and cavitation effects to generate deep lesions with an endocavitary applicator using a plane transducer: ex vivo studies.
Purpose To our knowledge the optimal freeze cycle length in renal cryotherapy is unknown. Ten-minute time based freeze cycles were compared to temperature based freeze cycles to −20C. Materials and Methods Laparoscopic renal cryotherapy was performed on 16 swine. Time based trials consisted of a double 10-minute freeze separated by a 5-minute thaw. Temperature based trials were double cycles of 1, 5 or 10-minute freeze initiated after 1 of 4 sensors indicated −20C. A 5-minute active thaw was used between freeze cycles. Control trials consisted of cryoneedle placement for 25 minutes without freeze or thaw. Viability staining and histological analysis were done. Results There was no difference in cellular necrosis between any of the temperature based freeze cycles (p = 0.1). Time based freeze cycles showed more nuclear pyknosis, indicative of necrosis, than the 3 experimental freeze cycles for the renal cortex (p = 0.05) but not for the renal medulla (p = 0.61). Mean time to −20C for freeze cycle 1 was 19 minutes 10 seconds (range 9 to 46 minutes). In 4 of 21 trials (19%) −20C was never attained despite freezing for 25 to 63 minutes. Conclusions There was no difference in immediate cellular necrosis among double 1, 5 or 10-minute freeze cycles. Cellular necrosis was evident on histological analysis for trials in which −20C was attained and in freeze cycles based on time alone. With a standard 10-minute cryoablation period most treated parenchyma 1 cm from the probe never attained −20C. Cell death appeared to occur at temperatures warmer than −20C during renal cryotherapy.
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