Antileishmanial effects of γCdcPLI, a phospholipase A2 inhibitor from Crotalus durissus collilineatus snake serum, on Leishmania (Leishmania) amazonensis

BACKGROUND

Leishmaniasis, a neglected disease caused by the parasite Leishmania, is treated with drugs associated with high toxicity and limited efficacy, in addition to constant reports of the emergence of resistant parasites. In this context, snake serums emerge as good candidates since they are natural sources with the potential to yield novel drugs.

OBJECTIVES

We aimed to show the antileishmanial effects of γCdcPLI, a phospholipase A2 inhibitor from Crotalus durissus collilineatus snake serum, against Leishmania (Leishmania) amazonensis.

METHODS

Promastigotes forms were exposed to γCdcPLI, and we assessed the parasite viability and cell cycle, as well as invasion and proliferation assays.

FINDINGS

Despite the low cytotoxicity effect on macrophages, our data indicate that γCdcPLI has a direct effect on parasites promoting an arrest in the G1 phase and reduction in the G2/M phase at the highest dose tested. Moreover, this PLA2 inhibitor reduced the parasite infectivity when promastigotes were pre-treated. Also, we demonstrated that the γCdcPLI treatment modulated the host cell environment impairing early and late steps of the parasitism.

MAIN CONCLUSIONS

γCdcPLI is an interesting tool for the discovery of new essential targets on the parasite, as well as an alternative compound to improve the effectiveness of the leishmaniasis treatment.

4-nerolidylcatechol (4-NC) and Docetaxel Synergize in Controlling Androgen-independent Prostate Cancer Cells

BACKGROUND

Effective cancer treatment still challenges medicine since the strategies employed so far are not sufficiently safe and capable of specifically eliminating tumor cells. Prostate cancer (PCa) is a highly incident malignant neoplasm, and the outcome of patients, especially those with advanced castration-resistant PCa (CRPC), depends directly on the efficacy of the therapeutic agents, such as docetaxel (DOC).

OBJECTIVE

This study investigated the synergistic potentiation of 4-nerolidylcatechol (4-NC) with DOC in inhibiting androgen-independent PCa cells.

METHODS

The cytotoxic effect of 4-NC was evaluated against non-tumorigenic (RWPE-01) and PCa cell lines (LNCaP and PC-3), and the antiproliferative potential of 4-NC was assessed by flow cytometry and colony formation. The Chou-Talalay method was applied to detect the synergistic effect of 4-NC and DOC, and the mechanism of anticancer activities of this combination was investigated by analyzing players in epithelial-mesenchymal transition (EMT).

RESULTS

4-NC significantly reduced the viability of PC-3 cells in a dose-dependent manner, decreasing colony formation and proliferation. The combination of 4-NC and DOC was synergistic in the androgen-independent cells and allowed the reduction of DOC concentration, with increased cytotoxicity and induction of apoptosis when compared to compounds alone. Furthermore, when 4-NC was co-administered with DOC, higher expression levels of proteins associated with the epithelial phenotype were observed, controlling EMT in PC-3 cells.

CONCLUSION

Collectively, these data demonstrated, for the first time, that the combination of 4-NC with reduced doses of DOC could be especially valuable in the suppression of oncogenic mechanisms of androgen-independent PCa cells.

A New Approach to Inhibiting Triple-Negative Breast Cancer: In Vitro, Ex Vivo and In Vivo Antiangiogenic Effect of BthTx-II, a PLA2-Asp-49 from Bothrops jararacussu Venom

Phospholipases A2 (PLA2) represent a superfamily of enzymes widely distributed in living organisms, with a broad spectrum of pharmacological activities and therapeutic potential. Anti-angiogenic strategies have become one of the main tools in fighting cancer. In this sense, the present work reports the inhibition of tumor angiogenesis induced by Asp-49 BthTX-II using in vitro, ex vivo and in vivo approaches. We demonstrate that BthTx-II inhibited cell adhesion, proliferation, and migration of human umbilical vein endothelial cells (HUVEC), as well as caused a reduction in the levels of endothelial growth factor (VEGF) during in vitro angiogenesis assays. BthTx-II was also able to inhibit the sprouting angiogenic process, by the ex vivo germination assay of the aortic ring; in addition, this toxin inhibited the migration and proliferation of HUVEC in co-culture with triple-negative breast cancer cells (e.g., MDA-MB-231 cells). Finally, in vivo tumor suppression and anti-angiogenic activities were analyzed using MDA-MB-231 cells with Matrigel injected into the chorioallantoic membrane of chicken embryo (CAM) for 7 days treatment with BthTx-II, showing a considerable reduction in vessel caliber, on the size and weight of tumors. Together, these results suggest an important antiangiogenic and antitumor role for BthTx-II, as a potential prototype for the development of new tools and antitumor drugs in cancer therapy.

A selective CuII complex with 4-fluorophenoxyacetic acid hydrazide and phenanthroline displays DNA-cleaving and pro-apoptotic properties in cancer cells

The thin line between efficacy and toxicity has challenged cancer therapy. As copper is an essential micronutrient and is important to tumor biology, CuII complexes emerged as an alternative to chemotherapy; however, its biological properties need to be better understood. Thus, we report in vitro the antitumor effects of two CuII complexes named [Cu(4-fh)(phen)(ClO4)2] (complex 1) and [Cu(4-nh)(phen)(ClO4)2]·H2O (complex 2), in which 4-fh = 4-fluorophenoxyacetic acid hydrazide; 4-nh = 4-nitrobenzoic hydrazide and phen = 1,10-phenanthroline. Both complexes presented cytotoxic activity against tumor cells, but only complex 1 showed significant selectivity. Complex 1 also induced DNA-damage, led to G0/G1 arrest and triggered apoptosis, which was initiated by an autophagy dysfunction. The significant in vitro selectivity and the action mechanism of complex 1 are noteworthy and reveal this prodrug as promising for anticancer therapy.

Phospholipase A2 Drives Tumorigenesis and Cancer Aggressiveness through Its Interaction with Annexin A1

Phospholipids are suggested to drive tumorigenesis through their essential role in inflammation. Phospholipase A₂ (PLA₂) is a phospholipid metabolizing enzyme that releases free fatty acids, mostly arachidonic acid, and lysophospholipids, which contribute to the development of the tumor microenvironment (TME), promoting immune evasion, angiogenesis, tumor growth, and invasiveness. The mechanisms mediated by PLA₂ are not fully understood, especially because an important inhibitory molecule, Annexin A1, is present in the TME but does not exert its action. Here, we will discuss how Annexin A1 in cancer does not inhibit PLA₂ leading to both pro-inflammatory and pro-tumoral signaling pathways. Moreover, Annexin A1 promotes the release of cancer-derived exosomes, which also lead to the enrichment of PLA₂ and COX-1 and COX-2 enzymes, contributing to TME formation. In this review, we aim to describe the role of PLA₂ in the establishment of TME, focusing on cancer-derived exosomes, and modulatory activities of Annexin A1. Unraveling how these proteins interact in the cancer context can reveal new strategies for the treatment of different tumors. We will also describe the possible strategies to inhibit PLA₂ and the approaches that could be used in order to resume the anti-PLA₂ function of Annexin A1.