Targeting MTHFD2 to Exploit Cancer-Specific Metabolism and the DNA Damage Response.

The one-carbon folate enzyme methylenetetrahydrofolate dehydrogenase/cyclohydrolase 2 (MTHFD2) is a promising therapeutic target in cancer. MTHFD2 is upregulated across numerous cancer types, promotes growth and metastasis of cancer, and correlates with poorer survival. Recent studies have developed small-molecule inhibitors to the isozymes MTHFD2 and MTHFD1 that show promise as anticancer agents through different mechanisms. This review discusses the current understanding of the function of MTHFD2 in cancer and the status of inhibitors for treating MTHFD2-overexpressing cancers.

A Bifunctional PARP-HDAC Inhibitor with Activity in Ewing Sarcoma.

PURPOSE: Histone deacetylase (HDAC) inhibition has been shown to induce pharmacologic "BRCAness" in cancer cells with proficient DNA repair activity. This provides a rationale for exploring combination treatments with HDAC and PARP inhibition in cancer types that are insensitive to single-agent PARP inhibitors (PARPi). Here, we report the concept and characterization of a novel bifunctional PARPi (kt-3283) with dual activity toward PARP1/2 and HDAC enzymes in Ewing sarcoma cells. EXPERIMENTAL DESIGN: Inhibition of PARP1/2 and HDAC was measured using PARP1/2, HDAC activity, and PAR formation assays. Cytotoxicity was assessed by IncuCyte live cell imaging, CellTiter-Glo, and spheroid assays. Cell-cycle profiles were determined using propidium iodide staining and flow cytometry. DNA damage was examined by γH2AX expression and comet assay. Inhibition of metastatic potential by kt-3283 was evaluated via ex vivo pulmonary metastasis assay (PuMA). RESULTS: Compared with FDA-approved PARP (olaparib) and HDAC (vorinostat) inhibitors, kt-3283 displayed enhanced cytotoxicity in Ewing sarcoma models. The kt-3283-induced cytotoxicity was associated with strong S and G2-M cell-cycle arrest in nanomolar concentration range and elevated DNA damage as assessed by γH2AX tracking and comet assays. In three-dimensional spheroid models of Ewing sarcoma, kt-3283 showed efficacy in lower concentrations than olaparib and vorinostat, and kt-3283 inhibited colonization of Ewing sarcoma cells in the ex vivo PuMA model. CONCLUSIONS: Our data demonstrate the preclinical justification for studying the benefit of dual PARP and HDAC inhibition in the treatment of Ewing sarcoma in a clinical trial and provides proof-of-concept for a bifunctional single-molecule therapeutic strategy.

Formate overflow drives toxic folate trapping in MTHFD1 inhibited cancer cells.

Cancer cells fuel their increased need for nucleotide supply by upregulating one-carbon (1C) metabolism, including the enzymes methylenetetrahydrofolate dehydrogenase-cyclohydrolase 1 and 2 (MTHFD1 and MTHFD2). TH9619 is a potent inhibitor of dehydrogenase and cyclohydrolase activities in both MTHFD1 and MTHFD2, and selectively kills cancer cells. Here, we reveal that, in cells, TH9619 targets nuclear MTHFD2 but does not inhibit mitochondrial MTHFD2. Hence, overflow of formate from mitochondria continues in the presence of TH9619. TH9619 inhibits the activity of MTHFD1 occurring downstream of mitochondrial formate release, leading to the accumulation of 10-formyl-tetrahydrofolate, which we term a 'folate trap'. This results in thymidylate depletion and death of MTHFD2-expressing cancer cells. This previously uncharacterized folate trapping mechanism is exacerbated by physiological hypoxanthine levels that block the de novo purine synthesis pathway, and additionally prevent 10-formyl-tetrahydrofolate consumption for purine synthesis. The folate trapping mechanism described here for TH9619 differs from other MTHFD1/2 inhibitors and antifolates. Thus, our findings uncover an approach to attack cancer and reveal a regulatory mechanism in 1C metabolism.

In vitro selection and characterization of probiotic properties in eight lactobacillus strains isolated from cocoa fermentation.

Traditionally, probiotic microorganisms are isolated from human and animal intestinal microbiota. However, the demand for diversification of biofunctional products has driven the search for new sources of probiotic candidates, such as fermented foods and vegetables. The present study found that strains isolated from the fermentation of fine cocoa from southern Bahia have biotechnological potential for use as a probiotic, since they showed capacity for self-aggregation and co-aggregation, antimicrobial activity against intestinal pathogens and resistance to gastrointestinal transits. Scores of importance for each property were established in order to more accurately assess the probiotic potential of the strains. The tests carried out contemplate the criteria previously established for the selection of probiotic candidates.

Antagonistic activity of Lactiplantibacillus plantarum 6.2 extracted from cocoa fermentation and its supernatant on Gardnerella vaginalis.

Search for alternative methods for the treatment of bacterial vaginosis has been growing, and probiotics being among them. The most well-known probiotic microorganisms are lactobacilli, which are naturally present in the vaginal microenvironment. Cocoa fermentation is a source of lactic acid bacteria, with lactobacilli being the most prominent. The aim of this study was to evaluate the antagonistic activity of Lactiplantibacillus plantarum 6.2 a strain of lactobacilli isolated from cocoa fermentation, and its cell-free supernatant on Gardnerella vaginalis. It was shown that Lpb. plantarum 6.2 and its supernatant, used at three concentrations, i.e., 40, 20 and 10 mg/mL, have a strong antagonistic activity against G. vaginalis, with a probable action of proteinaceous bacteriocins; the activity was lost after heat treatment. The ability to exclude and displace G. vaginalis from the adhesion site to vaginal HMVII epithelial cells was also demonstrated by the lactobacilli and the supernatant, with the latter showing a bactericidal effect. Thus, the Lpb. plantarum 6.2 strain presents itself as a good probiotic with potential to be used not only as a therapeutic alternative for vaginosis but also as a complement to existing therapies.

In Vitro Activity of Lactobacilli with Probiotic Potential Isolated from Cocoa Fermentation against Gardnerella vaginalis.

Study of the probiotic potential of microorganisms isolated from fermented foods has been increasing, especially studies related to lactobacilli. In intestinal models, lactobacilli have demonstrated beneficial properties, such as anti-inflammatory activity and increased antibody production, but the molecular mechanisms involving probiotic and antagonistic action as well as their effect on human vaginal cells have not yet been fully elucidated. The aim of this study was to evaluate the functional and antagonistic properties of three strains of lactobacilli isolated from cocoa fermentation (Lactobacillus fermentum 5.2, L. plantarum 6.2, and L. plantarum 7.1) against Gardnerella vaginalis. Our results show that the lactobacilli have potential use as probiotics, since they have high hydrophobicity and autoaggregation properties and effectively adhere to vaginal cells. Metabolites secreted into the culture medium and whole cells of the strains under study are capable of interfering with the growth of G. vaginalis to different degrees. The elucidation of the antagonistic mechanisms as well as their effect on human cells may be useful in the development of a product containing such microorganisms or products secreted by them.