Specific and shared biological functions of PARP2 - is PARP2 really a lil' brother of PARP1?

PARP2, that belongs to the family of ADP-ribosyl transferase enzymes (ART), is a discovery of the millennium, as it was identified in 1999. Although PARP2 was described initially as a DNA repair factor, it is now evident that PARP2 partakes in the regulation or execution of multiple biological processes as inflammation, carcinogenesis and cancer progression, metabolism or oxidative stress-related diseases. Hereby, we review the involvement of PARP2 in these processes with the aim of understanding which processes are specific for PARP2, but not for other members of the ART family. A better understanding of the specific functions of PARP2 in all of these biological processes is crucial for the development of new PARP-centred selective therapies.

The bacterial metabolite, lithocholic acid, has antineoplastic effects in pancreatic adenocarcinoma.

Lithocholic acid (LCA) is a secondary bile acid. LCA enters the circulation after bacterial synthesis in the gastrointestinal tract, reaches distantly located cancer cells, and influences their behavior. LCA was considered carcinogenic, but recent studies demonstrated that LCA has antitumor effects. We assessed the possible role of LCA in pancreatic adenocarcinoma. At the serum reference concentration, LCA induced a multi-pronged antineoplastic program in pancreatic adenocarcinoma cells. LCA inhibited cancer cell proliferation and induced mesenchymal-to-epithelial (MET) transition that reduced cell invasion capacity. LCA induced oxidative/nitrosative stress by decreasing the expression of nuclear factor, erythroid 2-like 2 (NRF2) and inducing inducible nitric oxide synthase (iNOS). The oxidative/nitrosative stress increased protein nitration and lipid peroxidation. Suppression of oxidative stress by glutathione (GSH) or pegylated catalase (pegCAT) blunted LCA-induced MET. Antioxidant genes were overexpressed in pancreatic adenocarcinoma and decreased antioxidant levels correlated with better survival of pancreatic adenocarcinoma patients. Furthermore, LCA treatment decreased the proportions of cancer stem cells. Finally, LCA induced total and ATP-linked mitochondrial oxidation and fatty acid oxidation. LCA exerted effects through the farnesoid X receptor (FXR), vitamin D receptor (VDR), and constitutive androstane receptor (CAR). LCA did not interfere with cytostatic agents used in the chemotherapy of pancreatic adenocarcinoma. Taken together, LCA is a non-toxic compound and has antineoplastic effects in pancreatic adenocarcinoma.

Cell-free ascites from ovarian cancer patients induces Warburg metabolism and cell proliferation through TGFß-ERK signaling.

Ascites plays a key role in supporting the metastatic potential of ovarian cancer cells. Shear stress and carry-over of cancer cells by ascites flow support carcinogenesis and metastasis formation. In addition, soluble factors may participate in the procarcinogenic effects of ascites in ovarian cancer. This study aimed to determine the biological effects of cell-free ascites on carcinogenesis in ovarian cancer cells. Cell-free ascites from ovarian cancer patients (ASC) non-selectively induced cell proliferation in multiple models of ovarian cancer and untransformed primary human dermal fibroblasts. Furthermore, ASC induced a Warburg-type rearrangement of cellular metabolism in A2780 ovarian cancer cells characterized by increases in cellular oxygen consumption and glycolytic flux; increases in glycolytic flux were dominant. ASC induced mitochondrial uncoupling and fundamentally reduced fatty acid oxidation. Ascites-elicited effects were uniform among ascites specimens. ASC-elicited transcriptomic changes in A2780 ovarian cancer cells included induction of the TGFß-ERK/MEK pathway, which plays a key role in inducing cell proliferation and oncometabolism. ASC-induced gene expression changes, as well as the overexpression of members of the TGFß signaling system, were associated with poor survival in ovarian cancer patients. We provided evidence that the activation of the autocrine/paracrine of TGFß signaling system may be present in bladder urothelial carcinoma and stomach adenocarcinoma. Database analysis suggests that the TGFß system may feed forward bladder urothelial carcinoma and stomach adenocarcinoma. Soluble components of ASC support the progression of ovarian cancer. These results suggest that reducing ascites production may play an essential role in the treatment of ovarian cancer by inhibiting the progression and reducing the severity of the disease.

Identification of Bacterial Metabolites Modulating Breast Cancer Cell Proliferation and Epithelial-Mesenchymal Transition.

Breast cancer patients are characterized by the oncobiotic transformation of multiple microbiome communities, including the gut microbiome. Oncobiotic transformation of the gut microbiome impairs the production of antineoplastic bacterial metabolites. The goal of this study was to identify bacterial metabolites with antineoplastic properties. We constructed a 30-member bacterial metabolite library and screened the library compounds for effects on cell proliferation and epithelial-mesenchymal transition. The metabolites were applied to 4T1 murine breast cancer cells in concentrations corresponding to the reference serum concentrations. However, yric acid, glycolic acid, d-mannitol, 2,3-butanediol, and trans-ferulic acid exerted cytostatic effects, and 3-hydroxyphenylacetic acid, 4-hydroxybenzoic acid, and vanillic acid exerted hyperproliferative effects. Furthermore, 3-hydroxyphenylacetic acid, 4-hydroxybenzoic acid, 2,3-butanediol, and hydrocinnamic acid inhibited epithelial-to-mesenchymal (EMT) transition. We identified redox sets among the metabolites (d-mannitol-d-mannose, 1-butanol-butyric acid, ethylene glycol-glycolic acid-oxalic acid), wherein only one partner within the set (d-mannitol, butyric acid, glycolic acid) possessed bioactivity in our system, suggesting that changes to the local redox potential may affect the bacterial secretome. Of the nine bioactive metabolites, 2,3-butanediol was the only compound with both cytostatic and anti-EMT properties.

The pro- and antineoplastic effects of deoxycholic acid in pancreatic adenocarcinoma cell models.

BACKGROUND: Commensal bacteria secrete metabolites that reach distant cancer cells through the circulation and influence cancer behavior. Deoxycholic acid (DCA), a hormone-like metabolite, is a secondary bile acid specifically synthesized by intestinal microbes. DCA may have both pro- and antineoplastic effects in cancers. METHODS AND RESULTS: The pancreatic adenocarcinoma cell lines, Capan-2 and BxPC-3, were treated with 0.7 µM DCA, which corresponds to the reference concentration of DCA in human serum. DCA influenced the expression of epithelial to mesenchymal transition (EMT)-related genes, significantly decreased the expression level of the mesenchymal markers, transcription factor 7- like 2 (TCF7L2), snail family transcriptional repressor 2 (SLUG), CLAUDIN-1, and increased the expression of the epithelial genes, zona occludens 1 (ZO-1) and E-CADHERIN, as shown by real-time PCR and Western blotting. Consequently, DCA reduced the invasion capacity of pancreatic adenocarcinoma cells in Boyden chamber experiments. DCA induced the protein expression of oxidative/nitrosative stress markers. Moreover, DCA reduced aldehyde dehydrogenase 1 (ALDH1) activity in an Aldefluor assay and ALDH1 protein level, suggesting that DCA reduced stemness in pancreatic adenocarcinoma. In Seahorse experiments, DCA induced all fractions of mitochondrial respiration and glycolytic flux. The ratio of mitochondrial oxidation and glycolysis did not change after DCA treatment, suggesting that cells became hypermetabolic. CONCLUSION: DCA induced antineoplastic effects in pancreatic adenocarcinoma cells by inhibiting EMT, reducing cancer stemness, and inducing oxidative/nitrosative stress and procarcinogenic effects such as hypermetabolic bioenergetics.

Half-Sandwich Type Platinum-Group Metal Complexes of C-Glucosaminyl Azines: Synthesis and Antineoplastic and Antimicrobial Activities.

While platinum-based compounds such as cisplatin form the backbone of chemotherapy, the use of these compounds is limited by resistance and toxicity, driving the development of novel complexes with cytostatic properties. In this study, we synthesized a set of half-sandwich complexes of platinum-group metal ions (Ru(II), Os(II), Ir(III) and Rh(III)) with an N,N-bidentate ligand comprising a C-glucosaminyl group and a heterocycle, such as pyridine, pyridazine, pyrimidine, pyrazine or quinoline. The sugar-containing ligands themselves are unknown compounds and were obtained by nucleophilic additions of lithiated heterocycles to O-perbenzylated 2-nitro-glucal. Reduction of the adducts and, where necessary, subsequent protecting group manipulations furnished the above C-glucosaminyl heterocycles in their O-perbenzylated, O-perbenzoylated and O-unprotected forms. The derived complexes were tested on A2780 ovarian cancer cells. Pyridine, pyrazine and pyridazine-containing complexes proved to be cytostatic and cytotoxic on A2780 cells, while pyrimidine and quinoline derivatives were inactive. The best complexes contained pyridine as the heterocycle. The metal ion with polyhapto arene/arenyl moiety also impacted on the biological activity of the complexes. Ruthenium complexes with p-cymene and iridium complexes with Cp* had the best performance in ovarian cancer cells, followed by osmium complexes with p-cymene and rhodium complexes with Cp*. Finally, the chemical nature of the protective groups on the hydroxyl groups of the carbohydrate moiety were also key determinants of bioactivity; in particular, O-benzyl groups were superior to O-benzoyl groups. The IC50 values of the complexes were in the low micromolar range, and, importantly, the complexes were less active against primary, untransformed human dermal fibroblasts; however, the anticipated therapeutic window is narrow. The bioactive complexes exerted cytostasis on a set of carcinomas such as cell models of glioblastoma, as well as breast and pancreatic cancers. Furthermore, the same complexes exhibited bacteriostatic properties against multiresistant Gram-positive Staphylococcus aureus and Enterococcus clinical isolates in the low micromolar range.

Half sandwich-type osmium, ruthenium, iridium and rhodium complexes with bidentate glycosyl heterocyclic ligands induce cytostasis in platinum-resistant ovarian cancer cells and bacteriostasis in Gram-positive multiresistant bacteria.

The toxicity of and resistance to platinum complexes as cisplatin, oxaliplatin or carboplatin calls for the replacement of these therapeutic agents in clinical settings. We have previously identified a set of half sandwich-type osmium, ruthenium and iridium complexes with bidentate glycosyl heterocyclic ligands exerting specific cytostatic activity on cancer cells but not on non-transformed primary cells. The apolar nature of the complexes, conferred by large, apolar benzoyl protective groups on the hydroxyl groups of the carbohydrate moiety, was the main molecular feature to induce cytostasis. We exchanged the benzoyl protective groups to straight chain alkanoyl groups with varying length (3 to 7 carbon units) that increased the IC50 value as compared to the benzoyl-protected complexes and rendered the complexes toxic. These results suggest a need for aromatic groups in the molecule. The pyridine moiety of the bidentate ligand was exchanged for a quinoline group to enlarge the apolar surface of the molecule. This modification decreased the IC50 value of the complexes. The complexes containing [(η6-p-cymene)Ru(II)], [(η6-p-cymene)Os(II)] or [(η5-Cp*)Ir(III)] were biologically active unlike the complex containing [(η5-Cp*)Rh(III)]. The complexes with cytostatic activity were active on ovarian cancer (A2780, ID8), pancreatic adenocarcinoma (Capan2), sarcoma (Saos) and lymphoma cell lines (L428), but not on primary dermal fibroblasts and their activity was dependent on reactive oxygen species production. Importantly, these complexes were cytostatic on cisplatin-resistant A2780 ovarian cancer cells with similar IC50 values as on cisplatin-sensitive A2780 cells. In addition, the quinoline-containing Ru and Os complexes and the short chain alkanoyl-modified complexes (C3 and C4) proved to be bacteriostatic in multiresistant Gram-positive Enterococcus and Staphylococcus aureus isolates. Hereby, we identified a set of complexes with submicromolar to low micromolar inhibitory constants against a wide range of cancer cells, including platinum resistant cells and against multiresistant Gram-positive bacteria.

PARP-inhibition reprograms macrophages toward an anti-tumor phenotype.

Poly(ADP)ribosylation inhibitors (PARPis) are toxic to cancer cells with homologous recombination (HR) deficiency but not to HR-proficient cells in the tumor microenvironment (TME), including tumor-associated macrophages (TAMs). As TAMs can promote or inhibit tumor growth, we set out to examine the effects of PARP inhibition on TAMs in BRCA1-related breast cancer (BC). The PARPi olaparib causes reprogramming of TAMs toward higher cytotoxicity and phagocytosis. A PARPi-related surge in NAD+ increases glycolysis, blunts oxidative phosphorylation, and induces reverse mitochondrial electron transport (RET) with an increase in reactive oxygen species (ROS) and transcriptional reprogramming. This reprogramming occurs in the absence or presence of PARP1 or PARP2 and is partially recapitulated by addition of NAD derivative methyl-nicotinamide (MNA). In vivo and ex vivo, the effect of olaparib on TAMs contributes to the anti-tumor efficacy of the PARPi. In vivo blockade of the "don't-eat-me signal" with CD47 antibodies in combination with olaparib improves outcomes in a BRCA1-related BC model.

Targeting Multiresistant Gram-Positive Bacteria by Ruthenium, Osmium, Iridium and Rhodium Half-Sandwich Type Complexes With Bidentate Monosaccharide Ligands.

Bacterial resistance to antibiotics is an ever-growing problem in heathcare. We have previously identified a set of osmium(II), ruthenium(II), iridium(III) and rhodium(III) half-sandwich type complexes with bidentate monosaccharide ligands possessing cytostatic properties against carcinoma, lymphoma and sarcoma cells with low micromolar or submicromolar IC50 values. Importantly, these complexes were not active on primary, non-transformed cells. These complexes have now been assessed as to their antimicrobial properties and found to be potent inhibitors of the growth of reference strains of Staphylococcus aureus and Enterococcus faecalis (Gram-positive species), though the compounds proved inactive on reference strains of Pseudomonas aerugonisa, Escherichia coli, Candida albicans, Candida auris and Acinetobacter baumannii (Gram-negative species and fungi). Furthermore, clinical isolates of Staphylococcus aureus and Enterococcus sp. (both multiresistant and susceptible strains) were also susceptible to the organometallic complexes in this study with similar MIC values as the reference strains. Taken together, we identified a set of osmium(II), ruthenium(II), iridium(III) and rhodium(III) half-sandwich type antineoplastic organometallic complexes which also have antimicrobial activity among Gram-positive bacteria. These compounds represent a novel class of antimicrobial agents that are not detoxified by multiresistant bacteria suggesting a potential to be used to combat multiresistant infections.

The role of bile acids in carcinogenesis.

Bile acids are soluble derivatives of cholesterol produced in the liver that subsequently undergo bacterial transformation yielding a diverse array of metabolites. The bulk of bile acid synthesis takes place in the liver yielding primary bile acids; however, other tissues have also the capacity to generate bile acids (e.g. ovaries). Hepatic bile acids are then transported to bile and are subsequently released into the intestines. In the large intestine, a fraction of primary bile acids is converted to secondary bile acids by gut bacteria. The majority of the intestinal bile acids undergo reuptake and return to the liver. A small fraction of secondary and primary bile acids remains in the circulation and exert receptor-mediated and pure chemical effects (e.g. acidic bile in oesophageal cancer) on cancer cells. In this review, we assess how changes to bile acid biosynthesis, bile acid flux and local bile acid concentration modulate the behavior of different cancers. Here, we present in-depth the involvement of bile acids in oesophageal, gastric, hepatocellular, pancreatic, colorectal, breast, prostate, ovarian cancer. Previous studies often used bile acids in supraphysiological concentration, sometimes in concentrations 1000 times higher than the highest reported tissue or serum concentrations likely eliciting unspecific effects, a practice that we advocate against in this review. Furthermore, we show that, although bile acids were classically considered as pro-carcinogenic agents (e.g. oesophageal cancer), the dogma that switch, as lower concentrations of bile acids that correspond to their serum or tissue reference concentration possess anticancer activity in a subset of cancers. Differences in the response of cancers to bile acids lie in the differential expression of bile acid receptors between cancers (e.g. FXR vs. TGR5). UDCA, a bile acid that is sold as a generic medication against cholestasis or biliary surge, and its conjugates were identified with almost purely anticancer features suggesting a possibility for drug repurposing. Taken together, bile acids were considered as tumor inducers or tumor promoter molecules; nevertheless, in certain cancers, like breast cancer, bile acids in their reference concentrations may act as tumor suppressors suggesting a Janus-faced nature of bile acids in carcinogenesis.

Reactive Oxygen Species Production Is Responsible for Antineoplastic Activity of Osmium, Ruthenium, Iridium and Rhodium Half-Sandwich Type Complexes with Bidentate Glycosyl Heterocyclic Ligands in Various Cancer Cell Models.

Platinum complexes are used in chemotherapy, primarily as antineoplastic agents. In this study, we assessed the cytotoxic and cytostatic properties of a set of osmium(II), ruthenium(II), iridium(III) and rhodium(III) half-sandwich-type complexes with bidentate monosaccharide ligands. We identified 5 compounds with moderate to negligible acute cytotoxicity but with potent long-term cytostatic activity. These structure-activity relationship studies revealed that: (1) osmium(II) p-cymene complexes were active in all models, while rhodium(III) and iridium(III) Cp* complexes proved largely inactive; (2) the biological effect was influenced by the nature of the central azole ring of the ligands-1,2,3-triazole was the most effective, followed by 1,3,4-oxadiazole, while the isomeric 1,2,4-oxadiazole abolished the cytostatic activity; (3) we found a correlation between the hydrophobic character of the complexes and their cytostatic activity: compounds with O-benzoyl protective groups on the carbohydrate moiety were active, compared to O-deprotected ones. The best compound, an osmium(II) complex, had an IC50 value of 0.70 µM. Furthermore, the steepness of the inhibitory curve of the active complexes suggested cooperative binding; cooperative molecules were better inhibitors than non-cooperative ones. The cytostatic activity of the active complexes was abolished by a lipid-soluble antioxidant, vitamin E, suggesting that oxidative stress plays a major role in the biological activity of the complexes. The complexes were active on ovarian cancer, pancreatic adenocarcinoma, osteosarcoma and Hodgkin's lymphoma cells, but were inactive on primary, non-transformed human fibroblasts, indicating their applicability as potential anticancer agents.

ADP-ribosyltransferases, an update on function and nomenclature.

ADP-ribosylation, a modification of proteins, nucleic acids, and metabolites, confers broad functions, including roles in stress responses elicited, for example, by DNA damage and viral infection and is involved in intra- and extracellular signaling, chromatin and transcriptional regulation, protein biosynthesis, and cell death. ADP-ribosylation is catalyzed by ADP-ribosyltransferases (ARTs), which transfer ADP-ribose from NAD+ onto substrates. The modification, which occurs as mono- or poly-ADP-ribosylation, is reversible due to the action of different ADP-ribosylhydrolases. Importantly, inhibitors of ARTs are approved or are being developed for clinical use. Moreover, ADP-ribosylhydrolases are being assessed as therapeutic targets, foremost as antiviral drugs and for oncological indications. Due to the development of novel reagents and major technological advances that allow the study of ADP-ribosylation in unprecedented detail, an increasing number of cellular processes and pathways are being identified that are regulated by ADP-ribosylation. In addition, characterization of biochemical and structural aspects of the ARTs and their catalytic activities have expanded our understanding of this protein family. This increased knowledge requires that a common nomenclature be used to describe the relevant enzymes. Therefore, in this viewpoint, we propose an updated and broadly supported nomenclature for mammalian ARTs that will facilitate future discussions when addressing the biochemistry and biology of ADP-ribosylation. This is combined with a brief description of the main functions of mammalian ARTs to illustrate the increasing diversity of mono- and poly-ADP-ribose mediated cellular processes.

The involvement of oncobiosis and bacterial metabolite signaling in metastasis formation in breast cancer.

Breast cancer, the most frequent cancer in women, is characterized by pathological changes to the microbiome of breast tissue, the tumor, the gut, and the urinary tract. Changes to the microbiome are determined by the stage, grade, origin (NST/lobular), and receptor status of the tumor. This year is the 50th anniversary of when Hill and colleagues first showed that changes to the gut microbiome can support breast cancer growth, namely that the oncobiome can reactivate excreted estrogens. The currently available human and murine data suggest that oncobiosis is not a cause of breast cancer, but can support its growth. Furthermore, preexisting dysbiosis and the predisposition to cancer are transplantable. The breast's and breast cancer's inherent microbiome and the gut microbiome promote breast cancer growth by reactivating estrogens, rearranging cancer cell metabolism, bringing about a more inflammatory microenvironment, and reducing the number of tumor-infiltrating lymphocytes. Furthermore, the gut microbiome can produce cytostatic metabolites, the production of which decreases or blunts breast cancer. The role of oncobiosis in the urinary tract is largely uncharted. Oncobiosis in breast cancer supports invasion, metastasis, and recurrence by supporting cellular movement, epithelial-to-mesenchymal transition, cancer stem cell function, and diapedesis. Finally, the oncobiome can modify the pharmacokinetics of chemotherapeutic drugs. The microbiome provides novel leverage on breast cancer that should be exploited for better management of the disease.

Ruthenium Half-Sandwich Type Complexes with Bidentate Monosaccharide Ligands Show Antineoplastic Activity in Ovarian Cancer Cell Models through Reactive Oxygen Species Production.

Ruthenium complexes are developed as substitutes for platinum complexes to be used in the chemotherapy of hematological and gynecological malignancies, such as ovarian cancer. We synthesized and screened 14 ruthenium half-sandwich complexes with bidentate monosaccharide ligands in ovarian cancer cell models. Four complexes were cytostatic, but not cytotoxic on A2780 and ID8 cells. The IC50 values were in the low micromolar range (the best being 0.87 µM) and were similar to or lower than those of the clinically available platinum complexes. The active complexes were cytostatic in cell models of glioblastoma, breast cancer, and pancreatic adenocarcinoma, while they were not cytostatic on non-transformed human skin fibroblasts. The bioactive ruthenium complexes showed cooperative binding to yet unidentified cellular target(s), and their activity was dependent on reactive oxygen species production. Large hydrophobic protective groups on the hydroxyl groups of the sugar moiety were needed for biological activity. The cytostatic activity of the ruthenium complexes was dependent on reactive species production. Rucaparib, a PARP inhibitor, potentiated the effects of ruthenium complexes.

PARPs in lipid metabolism and related diseases.

PARPs and tankyrases (TNKS) represent a family of 17 proteins. PARPs and tankyrases were originally identified as DNA repair factors, nevertheless, recent advances have shed light on their role in lipid metabolism. To date, PARP1, PARP2, PARP3, tankyrases, PARP9, PARP10, PARP14 were reported to have multi-pronged connections to lipid metabolism. The activity of PARP enzymes is fine-tuned by a set of cholesterol-based compounds as oxidized cholesterol derivatives, steroid hormones or bile acids. In turn, PARPs modulate several key processes of lipid homeostasis (lipotoxicity, fatty acid and steroid biosynthesis, lipoprotein homeostasis, fatty acid oxidation, etc.). PARPs are also cofactors of lipid-responsive nuclear receptors and transcription factors through which PARPs regulate lipid metabolism and lipid homeostasis. PARP activation often represents a disruptive signal to (lipid) metabolism, and PARP-dependent changes to lipid metabolism have pathophysiological role in the development of hyperlipidemia, obesity, alcoholic and non-alcoholic fatty liver disease, type II diabetes and its complications, atherosclerosis, cardiovascular aging and skin pathologies, just to name a few. In this synopsis we will review the evidence supporting the beneficial effects of pharmacological PARP inhibitors in these diseases/pathologies and propose repurposing PARP inhibitors already available for the treatment of various malignancies.

Silencing of Poly(ADP-Ribose) Polymerase-2 Induces Mitochondrial Reactive Species Production and Mitochondrial Fragmentation.

PARP2 is a DNA repair protein. The deletion of PARP2 induces mitochondrial biogenesis and mitochondrial activity by increasing NAD+ levels and inducing SIRT1 activity. We show that the silencing of PARP2 causes mitochondrial fragmentation in myoblasts. We assessed multiple pathways that can lead to mitochondrial fragmentation and ruled out the involvement of mitophagy, the fusion-fission machinery, SIRT1, and mitochondrial unfolded protein response. Nevertheless, mitochondrial fragmentation was reversed by treatment with strong reductants, such as reduced glutathione (GSH), N-acetyl-cysteine (NAC), and a mitochondria-specific antioxidant MitoTEMPO. The effect of MitoTEMPO on mitochondrial morphology indicates the production of reactive oxygen species of mitochondrial origin. Elimination of reactive oxygen species reversed mitochondrial fragmentation in PARP2-silenced cells.

The role of the microbiome in ovarian cancer: mechanistic insights into oncobiosis and to bacterial metabolite signaling.

Ovarian cancer is characterized by dysbiosis, referred to as oncobiosis in neoplastic diseases. In ovarian cancer, oncobiosis was identified in numerous compartments, including the tumor tissue itself, the upper and lower female genital tract, serum, peritoneum, and the intestines. Colonization was linked to Gram-negative bacteria with high inflammatory potential. Local inflammation probably participates in the initiation and continuation of carcinogenesis. Furthermore, local bacterial colonies in the peritoneum may facilitate metastasis formation in ovarian cancer. Vaginal infections (e.g. Neisseria gonorrhoeae or Chlamydia trachomatis) increase the risk of developing ovarian cancer. Bacterial metabolites, produced by the healthy eubiome or the oncobiome, may exert autocrine, paracrine, and hormone-like effects, as was evidenced in breast cancer or pancreas adenocarcinoma. We discuss the possible involvement of lipopolysaccharides, lysophosphatides and tryptophan metabolites, as well as, short-chain fatty acids, secondary bile acids and polyamines in the carcinogenesis of ovarian cancer. We discuss the applicability of nutrients, antibiotics, and probiotics to harness the microbiome and support ovarian cancer therapy. The oncobiome and the most likely bacterial metabolites play vital roles in mediating the effectiveness of chemotherapy. Finally, we discuss the potential of oncobiotic changes as biomarkers for the diagnosis of ovarian cancer and microbial metabolites as possible adjuvant agents in therapy.

In Vivo Molecular Imaging of the Efficacy of Aminopeptidase N (APN/CD13) Receptor Inhibitor Treatment on Experimental Tumors Using 68Ga-NODAGA-c(NGR) Peptide.

INTRODUCTION: The aminopeptidase N (APN/CD13) receptor plays an important role in the neoangiogenic process and metastatic tumor cell invasion. Clinical and preclinical studies reported that bestatin and actinonin are cytotoxic to APN/CD13-positive tumors and metastases due to their APN/CD13-specific inhibitor properties. Our previous studies have already shown that 68Ga-labeled NGR peptides bind specifically to APN/CD13 expressing tumor cells. The APN/CD13 specificity of 68Ga-NGR radiopharmaceuticals enables the following of the efficacy of antiangiogenic therapy with APN/CD13-specific inhibitors using positron emission tomography (PET). The aim of this in vivo study was to assess the antitumor effect of bestatin and actinonin treatment in subcutaneous transplanted HT1080 and B16-F10 tumor-bearing animal models using 68Ga-NODAGA-c(NGR). MATERIALS AND METHODS: Three days after the inoculation of HT1080 and B16-F10 cells, mice were treated with intraperitoneal injection of bestatin (15 mg/kg) or actinonin (5 mg/kg) for 7 days. On the 5th and 10th day, in vivo PET scans and ex vivo biodistribution studies were performed 90 min after intravenous injection of 5.5 ± 0.2 MBq68Ga-NODAGA-c(NGR). RESULTS: Control-untreated HT1080 and B16-F10 tumors were clearly visualized by the APN/CD13-specific 68Ga-NODAGA-c(NGR) radiopharmaceutical. The western blot analysis also confirmed the strong APN/CD13 positivity in the investigated tumors. We found significantly (p ≤ 0.05) lower radiopharmaceutical uptake after bestatin treatment and higher radiotracer accumulation in the actinonin-treated HT1080 tumors. In contrast, significantly lower (p ≤ 0.01) 68Ga-NODAGA-c(NGR) accumulation was observed in both bestatin- and actinonin-treated B16-F10 melanoma tumors compared to the untreated-control tumors. Bestatin inhibited tumor growth and 68Ga-NODAGA-c(NGR) uptake in both tumor models. CONCLUSION: The bestatin treatment is suitable for suppressing the neoangiogenic process and APN/CD13 expression of experimental HT1080 and B16-F10 tumors; furthermore, 68Ga-NODAGA-c(NGR) is an applicable radiotracer for the in vivo monitoring of the efficacy of the APN/CD13 inhibition-based anticancer therapies.

PARP-1 involves in UVB-induced inflammatory response in keratinocytes and skin injury via regulation of ROS-dependent EGFR transactivation and p38 signaling.

UV irradiation can injure the epidermis, resulting in sunburn, inflammation, and cutaneous tissue disorders. Previous studies demonstrate that EGFR in keratinocytes can be activated by UVB and contributes to inflammation. Poly (ADP-ribose) polymerase-1 (PARP-1) is a nuclear enzyme and plays an essential role in DNA repair under moderate stress. In this study, we set out to understand how PARP-1 regulates UVB irradiation-induced skin injury and interplays with EGFR to mediate the inflammation response. We found that PARP-1 deficiency exacerbated the UVB-induced inflammation, water loss, and back skin damage in mice. In human primary keratinocytes, UVB can activate PARP-1 and enhance DNA damage upon PARP-1 gene silencing. Moreover, PARP-1 silencing and PARP inhibitor olaparib can suppress UVB-induced COX-2 and MMP-1 expression, but enhance TNF-α and IL-8 expression. In addition, EGFR silencing or EGFR inhibition by gefitinib can decrease UVB-induced COX-2, TNF-α, and IL-8 expression, suggesting EGFR activation via paracrine action can mediate UVB-induced inflammation responses. Immunoblotting data revealed that PARP-1 inhibition decreases UVB-induced EGFR and p38 activation. Pharmacological inhibition of p38 also dramatically led to the attenuation of UVB-induced inflammatory gene expression. Of note, genetic ablation of PARP-1 or EGFR can attenuate UVB-induced ROS production, and antioxidant NAC can attenuate UVB-induced EGFR-p38 signaling axis and PARP-1 activation. These data suggest the regulatory loops among EGFR, PARP-1, and ROS upon UVB stress. PARP-1 not only serves DNA repair function but also orchestrates interactions to EGFR transactivation and ROS production, leading to p38 signaling for inflammatory gene expression in keratinocytes.

Cyclobutane pyrimidine dimers from UVB exposure induce a hypermetabolic state in keratinocytes via mitochondrial oxidative stress.

Ultraviolet B radiation (UVB) is an environmental complete carcinogen, which induces and promotes keratinocyte carcinomas, the most common human malignancies. UVB induces the formation of cyclobutane pyrimidine dimers (CPDs). Repairing CPDs through nucleotide excision repair is slow and error-prone in placental mammals. In addition to the mutagenic and malignancy-inducing effects, UVB also elicits poorly understood complex metabolic changes in keratinocytes, possibly through CPDs. To determine the effects of CPDs, CPD-photolyase was overexpressed in keratinocytes using an N1-methyl pseudouridine-containing in vitro-transcribed mRNA. CPD-photolyase, which is normally not present in placental mammals, can efficiently and rapidly repair CPDs to block signaling pathways elicited by CPDs. Keratinocytes surviving UVB irradiation turn hypermetabolic. We show that CPD-evoked mitochondrial reactive oxygen species production, followed by the activation of several energy sensor enzymes, including sirtuins, AMPK, mTORC1, mTORC2, p53, and ATM, is responsible for the compensatory metabolic adaptations in keratinocytes surviving UVB irradiation. Compensatory metabolic changes consist of enhanced glycolytic flux, Szent-Györgyi-Krebs cycle, and terminal oxidation. Furthermore, mitochondrial fusion, mitochondrial biogenesis, and lipophagy characterize compensatory hypermetabolism in UVB-exposed keratinocytes. These properties not only support the survival of keratinocytes, but also contribute to UVB-induced differentiation of keratinocytes. Our results indicate that CPD-dependent signaling acutely maintains skin integrity by supporting cellular energy metabolism.