Nitro-fatty acids: promising agents for the development of new cancer therapeutics.

Nitro-fatty acids (NO-FAs) are endogenous pleiotropic lipid mediators regarded as promising drug candidates for treating inflammatory and fibrotic diseases. Over the past two decades, the anti-inflammatory and cytoprotective actions of NO-FAs and several molecular targets have been identified. More recently, preclinical studies have demonstrated their potential as prospective cancer therapeutics with favorable safety and tumor-selective profiles.

Small molecule nitroalkenes inhibit RAD51-mediated homologous recombination and amplify triple-negative breast cancer cell killing by DNA-directed therapies.

Nitro fatty acids (NO -FAs) are endogenously generated lipid signaling mediators from metabolic and inflammatory reactions between conjugated diene fatty acids and nitric oxide or nitrite-derived reactive species. NO -FAs undergo reversible Michael addition with hyperreactive protein cysteine thiolates to induce posttranslational protein modifications that can impact protein function. Herein, we report a novel mechanism of action of natural and non-natural nitroalkenes structurally similar to ( ) 10-nitro-octadec-9-enoic acid (CP-6), recently de-risked by preclinical Investigational New Drug-enabling studies and Phase 1 and Phase 2 clinical trials and found to induce DNA damage in a TNBC xenograft by inhibiting homologous-recombination (HR)-mediated repair of DNA double-strand breaks (DSB).

Small molecule nitroalkenes inhibit RAD51-mediated homologous recombination and amplify triple-negative breast cancer cell killing by DNA-directed therapies.

Nitro fatty acids (NO-FAs) are endogenously generated lipid signaling mediators from metabolic and inflammatory reactions between conjugated diene fatty acids and nitric oxide or nitrite-derived reactive species. NO-FAs undergo reversible Michael addition with hyperreactive protein cysteine thiolates to induce posttranslational protein modifications that can impact protein function. Herein, we report a novel mechanism of action of natural and non-natural nitroalkenes structurally similar to (E) 10-nitro-octadec-9-enoic acid (CP-6), recently de-risked by preclinical Investigational New Drug-enabling studies and Phase 1 and Phase 2 clinical trials and found to induce DNA damage in a TNBC xenograft by inhibiting homologous-recombination (HR)-mediated repair of DNA double-strand breaks (DSB).

Redox regulation of RAD51 Cys319 and homologous recombination by peroxiredoxin 1.

RAD51 is a critical recombinase that functions in concert with auxiliary mediator proteins to direct the homologous recombination (HR) DNA repair pathway. We show that Cys319 RAD51 possesses nucleophilic characteristics and is important for irradiation-induced RAD51 foci formation and resistance to inhibitors of poly (ADP-ribose) polymerase (PARP). We have previously identified that cysteine (Cys) oxidation of proteins can be important for activity and modulated via binding to peroxiredoxin 1 (PRDX1).

Peroxiredoxin-1 Tyr194 phosphorylation regulates LOX-dependent extracellular matrix remodelling in breast cancer.

Background: Peroxiredoxin 1 (PRDX1) belongs to an abundant family of peroxidases whose role in cancer is still unresolved. While mouse knockout studies demonstrate a tumour suppressive role for PRDX1, in cancer cell xenografts, results denote PRDX1 as a drug target. Probably, this phenotypic discrepancy stems from distinct roles of PRDX1 in certain cell types or stages of tumour progression.

3D Collagen Vascular Tumor-on-a-Chip Mimetics for Dynamic Combinatorial Drug Screening.

Disease models, including cell culture and animal models, have contributed significantly to developing diagnostics and treatments over the past several decades. The successes of traditional drug screening methods were generally hampered by not adequately mimicking critical features, such as a 3D microenvironment and dynamic drug diffusion through the extracellular matrix (ECM). To address these issues, we developed a 3D dynamic drug delivery system for cancer drug screening that mimicks drug dissemination through the tumor vasculature and the ECM by creating collagen-embedded microfluidic channels.

The peroxidase PRDX1 inhibits the activated phenotype in mammary fibroblasts through regulating c-Jun N-terminal kinases.

Background: Reactive oxygen species (ROS), including hydrogen peroxide, drive differentiation of normal fibroblasts into activated fibroblasts, which can generate high amounts of hydrogen peroxide themselves, thereby increasing oxidative stress in the microenvironment. This way, activated fibroblasts can transition into cancer-associated fibroblasts (CAFs).

Methods: Mammary fibroblasts from either female 8 weeks old PRDX1 knockout and wildtype mice or Balb/c mice were studied for characteristic protein expression using immunofluorescence and immunoblotting.

Redoxins as gatekeepers of the transcriptional oxidative stress response.

Transcription factors control the rate of transcription of genetic information from DNA to messenger RNA, by binding specific DNA sequences in promoter regions. Transcriptional gene control is a rate-limiting process that is tightly regulated and based on transient environmental signals which are translated into long-term changes in gene transcription. Post-translational modifications (PTMs) on transcription factors by phosphorylation or acetylation have profound effects not only on sub-cellular localization but also on substrate specificity through changes in DNA binding capacity.

Signals Getting Crossed in the Entanglement of Redox and Phosphorylation Pathways: Phosphorylation of Peroxiredoxin Proteins Sparks Cell Signaling.

Reactive oxygen and nitrogen species have cell signaling properties and are involved in a multitude of processes beyond redox homeostasis. The peroxiredoxin (Prdx) proteins are highly sensitive intracellular peroxidases that can coordinate cell signaling via direct reactive species scavenging or by acting as a redox sensor that enables control of binding partner activity. Oxidation of the peroxidatic cysteine residue of Prdx proteins are the classical post-translational modification that has been recognized to modulate downstream signaling cascades, but increasing evidence supports that dynamic changes to phosphorylation of Prdx proteins is also an important determinant in redox signaling.

Electrophilic fatty acids impair RAD51 function and potentiate the effects of DNA-damaging agents on growth of triple-negative breast cells.

Homologous recombination (HR)-directed DNA double-strand break (DSB) repair enables template-directed DNA repair to maintain genomic stability. RAD51 recombinase (RAD51) is a critical component of HR and facilitates DNA strand exchange in DSB repair. We report here that treating triple-negative breast cancer (TNBC) cells with the fatty acid nitroalkene 10-nitro-octadec-9-enoic acid (OA-NO) in combination with the antineoplastic DNA-damaging agents doxorubicin, cisplatin, olaparib, and γ-irradiation (IR) enhances the antiproliferative effects of these agents.

Expression of reactive species related genes is associated with patient survival in luminal B breast cancer.

Increased reactive species (RS; reactive oxygen and nitrogen species) are a byproduct of both enzymatic and non-enzymatic systems, and critical in cancer development, including breast tumorigenesis. To investigate the role of RS-related genes in breast cancer, expression levels of the most common annotated genes involved in regulating cellular RS levels and proteins that are substrates of RS in specific subtypes of breast cancer 9 were evaluated using public data bases. Based on the premise that increased RS promote tumor formation, and breast cancer subtypes vary in aggressiveness, we hypothesized that specific RS gene expression signatures are associated with breast cancer aggressiveness and patient survival.

Peroxiredoxin Involvement in the Initiation and Progression of Human Cancer.

Significance: It has been proposed that cancer cells are heavily dependent on their antioxidant defenses for survival and growth. Peroxiredoxins are a family of abundant thiol-dependent peroxidases that break down hydrogen peroxide, and they have a central role in the maintenance and response of cells to alterations in redox homeostasis. As such, they are potential targets for disrupting tumor growth.

Nitro-fatty acid inhibition of triple-negative breast cancer cell viability, migration, invasion, and tumor growth.

Triple-negative breast cancer (TNBC) comprises ∼20% of all breast cancers and is the most aggressive mammary cancer subtype. Devoid of the estrogen and progesterone receptors, along with the receptor tyrosine kinase ERB2 (HER2), that define most mammary cancers, there are no targeted therapies for patients with TNBC. This, combined with a high metastatic rate and a lower 5-year survival rate than for other breast cancer phenotypes, means there is significant unmet need for new therapeutic strategies.

A Peroxidase Peroxiredoxin 1-Specific Redox Regulation of the Novel FOXO3 microRNA Target let-7.

Precision in redox signaling is attained through posttranslational protein modifications such as oxidation of protein thiols. The peroxidase peroxiredoxin 1 (PRDX1) regulates signal transduction through changes in thiol oxidation of its cysteines. We demonstrate here that PRDX1 is a binding partner for the tumor suppressive transcription factor FOXO3 that directly regulates the FOXO3 stress response.

Role of oxidative stress and the microenvironment in breast cancer development and progression.

Breast cancer is a highly complex tissue composed of neoplastic and stromal cells. Carcinoma-associated fibroblasts (CAFs) are commonly found in the cancer stroma, where they promote tumor growth and enhance vascularity in the microenvironment. Upon exposure to oxidative stress, fibroblasts undergo activation to become myofibroblasts.

LBoost: A boosting algorithm with application for epistasis discovery.

Many human diseases are attributable to complex interactions among genetic and environmental factors. Statistical tools capable of modeling such complex interactions are necessary to improve identification of genetic factors that increase a patient's risk of disease. Logic Forest (LF), a bagging ensemble algorithm based on logic regression (LR), is able to discover interactions among binary variables predictive of response such as the biologic interactions that predispose individuals to disease.

Secreted Hsp90 is a novel regulator of the epithelial to mesenchymal transition (EMT) in prostate cancer.

Prostate cancer (PCa) is the most frequently diagnosed malignancy in men, and the second highest contributor of male cancer related lethality. Disease mortality is due primarily to metastatic spread, highlighting the urgent need to identify factors involved in this progression. Activation of the genetic epithelial to mesenchymal transition (EMT) program is implicated as a major contributor of PCa progression.

Oncogenic K-Ras regulates bioactive sphingolipids in a sphingosine kinase 1-dependent manner.

Sphingosine kinase 1 (SK1) is an important enzyme involved in the production of the bioactive lipid sphingosine 1-phosphate (S1P). SK1 is overexpressed in many forms of cancer, however, the contribution of SK1 to cancer progression is still unclear. One of the best characterized mutations found in several forms of human cancer is an activating point mutation in the Ras oncogene, which disrupts its GTPase activity and leads to stimulation of the MEK/ERK pathway.

Influence of mercury and selenium chemistries on the progression of cardiomyopathy in pygmy sperm whales, Kogia breviceps.

More than half of pygmy sperm whales (Kogia breviceps) that strand exhibit signs of cardiomyopathy (CMP). Many factors may contribute to the development of idiopathic CMP in K. breviceps, including genetics, infectious agents, contaminants, biotoxins, and dietary intake (e.

Prdx1 deficiency in mice promotes tissue specific loss of heterozygosity mediated by deficiency in DNA repair and increased oxidative stress.

The loss of the H(2)O(2) scavenger protein encoded by Prdx1 in mice leads to an elevation of reactive oxygen species (ROS) and tumorigenesis of different tissues. Loss of heterozygosity (LOH) mutations could initiate tumorigenesis through loss of tumor suppressor gene function in heterozygous somatic cells. A connection between the severity of ROS and the frequency of LOH mutations in vivo has not been established.

Autophagy regulates keratin 8 homeostasis in mammary epithelial cells and in breast tumors.

Autophagy is activated in response to cellular stressors and mediates lysosomal degradation and recycling of cytoplasmic material and organelles as a temporary cell survival mechanism. Defective autophagy is implicated in human pathology, as disruption of protein and organelle homeostasis enables disease-promoting mechanisms such as toxic protein aggregation, oxidative stress, genomic damage, and inflammation. We previously showed that autophagy-defective immortalized mouse mammary epithelial cells are susceptible to metabolic stress, DNA damage, and genomic instability.

Peroxiredoxin 1 and its role in cell signaling.

Peroxiredoxins (Prdxs) are a family of small (22-27 kDa) nonseleno peroxidases currently known to possess six mammalian isoforms. Although their individual roles in cellular redox regulation and antioxidant protection are quite distinct, they all catalyze peroxide reduction of H(2)O(2), organic hydroperoxides and peroxynitrite. They are found to be expressed ubiquitously and in high levels, suggesting that they are both an ancient and important enzyme family.

Prdx1 inhibits tumorigenesis via regulating PTEN/AKT activity.

It is widely accepted that reactive oxygen species (ROS) promote tumorigenesis. However, the exact mechanisms are still unclear. As mice lacking the peroxidase peroxiredoxin1 (Prdx1) produce more cellular ROS and die prematurely of cancer, they offer an ideal model system to study ROS-induced tumorigenesis.

Are peroxiredoxins tumor suppressors?

It has been known for many years that free radicals, such as reactive oxygen species (ROS) and reactive nitrogen species (RNS), promote diseases such as cancer. Peroxiredoxins (Prdxs) are small H(2)O(2) scavenging proteins that appear to have tumor preventive functions since loss of Prdx1 in mice leads to premature death from cancer. However, as Prdxs are antioxidants they also scavenge the H(2)O(2) in cancer cells that way supporting survival and tumor maintenance.

Genetic replacement of cyclin D1 function in mouse development by cyclin D2.

D cyclins (D1, D2, and D3) are components of the core cell cycle machinery in mammalian cells. It is unclear whether each of the D cyclins performs unique, tissue-specific functions or the three proteins have virtually identical functions and differ mainly in their pattern of expression. We previously generated mice lacking cyclin D1, and we observed that these animals displayed hypoplastic retinas and underdeveloped mammary glands and a presented developmental neurological abnormality.