Significance Prostate cancer is the most common malignancy and the third leading cancer-related cause of death among men of the Western world. Treatment options at advanced stages of the disease are scarce, and better therapies are in urgent need. In our study, we show that the clinically relevant lipid kinase phosphatidylinositol-4-phosphate 5-kinase-α (PIP5Kα) plays an important role in cancer cell invasion and survival by regulating the PI3K/AKT/androgen receptor pathways. Elevated levels of PIP5K1α contribute to cancer cell proliferation, survival, and invasion. In this context we introduce a newly developed compound, ISA-2011B, with promising anticancer effects by inhibiting the PIP5K1α-associated AKT pathways. Conclusively, we propose that PIP5K1α may be used as a potential therapeutic target for treatment of advanced prostate cancer.

Immunometabolism is emerging as a critical determinant of cancer pathophysiology. In this study, we explored the contributions of macrophage-expressed lactate dehydrogenase-A (LDH-A) to tumor formation in a K-Ras murine model of lung carcinoma. Myeloid-specific deletion of LDH-A promoted accumulation of macrophages with a CD86high and MCP-1high M1-like phenotype that suppressed tumor growth. This phenotypic effect was accompanied by reduced VEGF expression and angiogenesis; diminished numbers of PD-L1+ cancer cells; increased numbers of CD3+ T cells and activation status of CD8+ T cells. Further, it was associated with more pronounced antitumor T cell immunity via induction of IL-17 and IFNγ-producing CD8+ T (Tc17 and Tc1) cells, likely via suppression of lactate-driven PD-L1 expression. Our results suggest that expression of LDH-A and lactate by macrophage in the tumor microenvironment are major drivers of T cell immunosuppression, strongly supporting the concept of targeting stromal LDH-A as an effective strategy to blunt tumoral immune escape.

Stability and repair of DNA is of principal importance in cell survival. Heme oxygenase-1 (HO-1; Hmox1) is critical in maintaining cellular homeostasis, in large part through its ability to generate CO, but neither molecule has been studied in the setting of DNA damage. Naïve Hmox1 −/− mice exhibit excessive tissue levels of γ-histone H2A, whereas administration of genotoxic stressors or irradiation in HO-1-deficient cells resulted in loss of ataxia-telangiectasia mutated/ataxia telangiectasia and Rad3-related protein and breast cancer 1, early onset induction with dysfunctional γ-H2AX foci and marked elevations in DNA damage. HO-1 induction or exposure to CO induced homologous recombination-mediated DNA repair through ataxia-telangiectasia mutated/ataxia telangiectasia and Rad3-related protein. In vivo, exposure of mice to CO followed by genotoxin (Adriamycin) or radiation-induced injury led to diminished tissue DNA damage and improved survival. We characterize a joint role for HO-1 and the gasotransmitter CO for appropriate DNA repair and provide a mechanism for their potent cytoprotective effects in various pathologies.chemotherapy | heme degradation | gas biology | cytoprotection E fficient DNA damage repair and checkpoint mechanisms are critical components of normal cellular function to maintain the integrity of genomic DNA (reviewed in refs. 1 and 2). DNA lesions are induced in response to UV or ionizing radiation as well as many chemicals including endogenous metabolites and reactive oxygen species (ROS) (1). DNA repair pathways include repair of damaged bases or single-strand DNA breaks (base excision repair) and repair of double-strand DNA breaks (DSB) including homologous recombination (HR) and nonhomologous end-joining (NHEJ). The cellular response to DNA DSBs occurs via an integrated sensing and signaling network that maintains and restores genomic stability (3). DSBs are detected initially by damage sensors that trigger the activation of transducing kinases. These transducers amplify the damage signal and relay it to effector proteins, which in turn regulate cell-cycle progression, DNA repair, and apoptosis (4). DSBs are recognized by the Mre11-Rad50-Nbs1 (MRN) mediator complex which recruits ataxia telangiectasia-mutated (ATM) to the broken DNA (4). Cells also are faced with detection of replication blocks, which is mediated by an ssDNA-replication protein A complex recruiting the kinases ataxia-telangiectasia and rad3-related (ATR) and Rad17 (5). Both ATR and ATM can phosphorylate multiple target proteins [p53 binding protein 1, breast cancer 1, early onset (Brca1), checkpoint kinase 1, checkpoint kinase 2 (Chk2), and the MRN complex, among others; more than 700 proteins have been identified so far] that mediate the downstream signaling. Further, in response to DNA damage or structural alterations of chromatin, histone H2A is phosphorylated on Ser139 by ATM, ATR, or by DNA-dependent protein kinases. This phosphorylation allows recruitment of additional DNA damage-responsive proteins and the format...

Critical functions of the immune system are maintained by the ability of myeloid progenitors to differentiate and mature into macrophages. We hypothesized that the cytoprotective gas molecule carbon monoxide (CO), generated endogenously by heme oxygenases (HO), promotes differentiation of progenitors into functional macrophages. Deletion of HO-1, specifically in the myeloid lineage (Lyz-Cre:Hmox1flfl), attenuated the ability of myeloid progenitors to differentiate toward macrophages and decreased the expression of macrophage markers, CD14 and macrophage colony-stimulating factor receptor (MCSFR). We showed that HO-1 and CO induced CD14 expression and efficiently increased expansion and differentiation of myeloid cells into macrophages. Further, CO sensitized myeloid cells to treatment with MCSF at low doses by increasing MCSFR expression, mediated partially through a PI3K-Akt-dependent mechanism. Exposure of mice to CO in a model of marginal bone marrow transplantation significantly improved donor myeloid cell engraftment efficiency, expansion and differentiation, which corresponded to increased serum levels of GM-CSF, IL-1α and MCP-1. Collectively, we conclude that HO-1 and CO in part are critical for myeloid cell differentiation. CO may prove to be a novel therapeutic agent to improve functional recovery of bone marrow cells in patients undergoing irradiation, chemotherapy and/or bone marrow transplantation.