Fidelity Variants of RNA Dependent RNA Polymerases Uncover an Indirect, Mutagenic Activity of Amiloride Compounds

In a screen for RNA mutagen resistance, we isolated a high fidelity RNA dependent RNA polymerase (RdRp) variant of Coxsackie virus B3 (CVB3). Curiously, this variant A372V is also resistant to amiloride. We hypothesize that amiloride has a previously undescribed mutagenic activity. Indeed, amiloride compounds increase the mutation frequencies of CVB3 and poliovirus and high fidelity variants of both viruses are more resistant to this effect. We hypothesize that this mutagenic activity is mediated through alterations in intracellular ions such as Mg2+ and Mn2+, which in turn increase virus mutation frequency by affecting RdRp fidelity. Furthermore, we show that another amiloride-resistant RdRp variant, S299T, is completely resistant to this mutagenic activity and unaffected by changes in ion concentrations. We show that RdRp variants resist the mutagenic activity of amiloride via two different mechanisms: 1) increased fidelity that generates virus populations presenting lower basal mutation frequencies or 2) resisting changes in divalent cation concentrations that affect polymerase fidelity. Our results uncover a new antiviral approach based on mutagenesis

La Familia: Videoclip creativo

Universidad de Sevilla. Grado en Comunicación Audiovisua

Targeting myeloid chemotaxis to reverse prostate cancer therapy resistance

Inflammation is a hallmark of cancer1. In cancer patients, peripheral blood myeloid expansion, indicated by a high neutrophil-to-lymphocyte ratio (NLR), associates with shorter survival and treatment resistance across malignancies and therapeutic modalities2-5. Whether myeloid inflammation drives prostate cancer progression in humans remain unclear. Herein we show that inhibition of myeloid chemotaxis can reduce tumour-elicited myeloid inflammation and reverse therapy resistance in a subset of metastatic castration-resistant prostate cancer (mCRPC) patients. We show that higher blood NLR reflects tumour myeloid infiltration and tumour expression of senescence-associated mRNA species including myeloid chemoattracting CXCR2 ligands. To determine whether myeloid cells fuel androgen receptor signaling inhibitor (ARSI) resistance, and if inhibiting CXCR2 to block myeloid chemotaxis reverses this, we conducted an investigator-initiated, proof-of-concept clinical trial of a CXCR2 inhibitor (AZD5069) plus enzalutamide in patients with ARSI-resistant mCRPC. This combination was well tolerated without dose-limiting toxicity and decreased circulating neutrophils, reduced intratumor CD11b+HLA-DRloCD15+CD14- myeloid cell infiltration, and imparted durable clinical benefit with biochemical and radiological responses in a subset of mCRPC patients. This study provides the first clinical evidence that senescence-associated myeloid inflammation can fuel mCRPC progression and resistance to AR blockade. Targeting myeloid chemotaxis merits broader evaluation in other cancers