The three major mitogen-activated protein kinases (MAPKs) p38, JNK, and ERK are signal transducers involved in a broad range of cell functions including survival, apoptosis, and cell differentiation. Whereas JNK and p38 have been generally linked to cell death and tumor suppression, ERK plays a prominent role in cell survival and tumor promotion, in response to a broad range of stimuli such as cytokines, growth factors, ultraviolet radiation, hypoxia, or pharmacological compounds. However, there is a growing body of evidence supporting that JNK and p38 also contribute to the development of a number of malignances. In this paper we focus on the involvement of the MAPK pathways in prostate cancer, including the less-known ERK5 pathway, as pro- or antitumor mediators, through their effects on apoptosis, survival, metastatic potential, and androgen-independent growth.

The three major mitogen-activated protein kinases (MAPKs) p38, JNK, and ERK are signal transducers involved in a broad range of cell functions including survival, apoptosis, and cell differentiation. Whereas JNK and p38 have been generally linked to cell death and tumor suppression, ERK plays a prominent role in cell survival and tumor promotion, in response to a broad range of stimuli such as cytokines, growth factors, ultraviolet radiation, hypoxia, or pharmacological compounds. However, there is a growing body of evidence supporting that JNK and p38 also contribute to the development of a number of malignances. In this paper we focus on the involvement of the MAPK pathways in prostate cancer, including the less-known ERK5 pathway, as pro-or antitumor mediators, through their effects on apoptosis, survival, metastatic potential, and androgen-independent growth.

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Cyclin-dependent kinase 1 (CDK1) orchestrates the transition from the G2 phase into mitosis and as cancer cells often display enhanced CDK1 activity, it has been proposed as a tumor specific anti-cancer target. Here we show that the effects of CDK1 inhibition are not restricted to tumor cells but can also reduce viability in non-cancer cells and sensitize them to radiation in a cell cycle dependent manner. Radiosensitization by the specific CDK1 inhibitor, RO-3306, was determined by colony formation assays in three tumor lines (HeLa, T24, SQ20B) and three non-cancer lines (HFL1, MRC-5, RPE). Initial results showed that CDK1 inhibition radiosensitized tumor cells, but did not sensitize normal fibroblasts and epithelial cells in colony formation assays despite effective inhibition of CDK1 signaling. Further investigation showed that normal cells were less sensitive to CDK1 inhibition because they remained predominantly in G1 for a prolonged period when plated in colony formation assays. In contrast, inhibiting CDK1 a day after plating, when the cells were going through G2/M phase, reduced their clonogenic survival both with and without radiation. Our finding that inhibition of CDK1 can damage normal cells in a cell cycle dependent manner indicates that targeting CDK1 in cancer patients may lead to toxicity in normal proliferating cells. Furthermore, our finding that cell cycle progression becomes easily stalled in non-cancer cells under normal culture conditions has general implications for testing anti-cancer agents in these cells.

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BackgroundIn this study was investigate IAPs in normal human prostate (NP), benign prostatic hyperplasia (BPH), prostatic intraepithelial neoplasia (PIN) and prostatic carcinoma (PC), and their involvement in apoptosis/proliferation via NF-kB (TNF-α, IL-1) stimulation.MethodsImmunohistochemical and Western blot analyses were performed in 10 samples of normal prostates, 35 samples of BPH, 27 samples diagnosis of PIN (with low-grade PIN or high-grade PIN) and 95 samples of PC (with low, medium or high Gleason grades).ResultsIn NP, cytoplasm of epithelial cells were positive to c-IAP1/2 (80% of samples), c-IAP-2 (60%), ILP (20%), XIAP (20%); negative to NAIP and survivin. In BPH, epithelial cells were immunostained to c-IAP1/2 (57.57%), c-IAP-2 (57.57%), ILP (66.6%), NAIP (60.6%), XIAP (27.27%), survivin (9.1%). Whereas low-grade PIN showed intermediate results between NP and BPH; results in high-grade PIN were similar to those found in PC. In PC, epithelial cells were immunostained to c-IAP1/2, c-IAP-2, ILP, NAIP, XIAP (no Gleason variation) and survivin (increasing with Gleason).ConclusionsIAPs could be involved in prostate disorder (BPH, PIN and PC) development since might be provoke inhibition of apoptosis and subsequently cell proliferation. At the same time, different transduction pathway such as IL-1/NIK/NF-kB or TNF/NF-kB (NIK or p38) also promotes proliferation. Inhibitions of IAPs, IL-1α and TNFα might be a possible target for PC treatment since IAPs are the proteins that inhibited apoptosis (favour proliferation) and IL-1α and TNFα would affect all the transduction pathway involucrate in the activation of transcription factors related to survival or proliferation (NF-kB, Elk-1 or ATF-2).

Purpose-Tumor hypoxia fuels an aggressive tumor phenotype and confers resistance to anticancer treatments. We conducted a clinical trial to determine whether the antimalarial drug atovaquone, a known mitochondrial inhibitor, reduces hypoxia in non-small cell lung cancer (NSCLC).Patients and methods-Patients with NSCLC scheduled for surgery were recruited sequentially into two cohorts: Cohort 1 received oral atovaquone at the standard clinical dose 750 mg twice-daily, whilst Cohort 2 did not. Primary imaging endpoint was change in tumor hypoxic volume (HV) measured by hypoxia PET-CT. Inter-cohort comparison of hypoxia gene expression signatures using RNA sequencing from resected tumors was performed.Results-Thirty patients were evaluable for hypoxia PET-CT analysis, 15 per cohort. Median treatment duration was 12 days. Eleven (73.3%) atovaquone-treated patients had meaningful HV reduction with median change −28.0% [95% confidence interval (CI), −58.2 to −4.4]. In contrast, median change in untreated patients was +15.5% (95% CI, −6.5 to 35.5). Linear regression estimated the expected mean HV was 55% (95% CI, 24% to 74%) lower in Cohort 1 compared to Cohort 2 (p=0.004), adjusting for cohort, tumor volume and baseline HV. A key pharmacodynamic endpoint was reduction in hypoxia regulated genes, which were significantly downregulated in atovaquone-treated tumors. Data from multiple additional measures of tumor hypoxia and perfusion are presented. No atovaquone-related adverse events were reported.Conclusions-This is the first clinical evidence that targeting tumor mitochondrial metabolism can reduce hypoxia and produce relevant anti-tumor effects at the mRNA level. Repurposing atovaquone for this purpose may improve treatment outcomes for NSCLC.

Highlights d SUMOylation and ubiquitylation enable DPC repair during DNA replication d Resolution of ubiquitylated and SUMOylated DPCs requires the protease SPRTN d Inactivation of SUMOylation after DPC formation activates homologous recombination d DPC SUMOylation and SPRTN prevent recombinationdependent genomic instability