Biology subjects

Gongora, C.

Publications and source records attributed to Gongora, C..

6 recordsLinked to original sources

bioRxiv2026

The Pregnane X Receptor (PXR) contributes to phenotypic plasticity and modulates the sensitivity to targeted therapies in melanoma

The challenge in treating advanced metastatic melanoma lies in the development of therapeutic resistance and the risk of recurrence. Understanding the mechanisms underlying tumor adaptation to treatment is therefore crucial, as they can directly influence therapeutic efficacy. Tolerance to targeted therapies may be influenced by drug transport and metabolism within tumors, processes regulated by numerous genes under the transcriptional control of the nuclear receptor PXR (Pregnane X Receptor, NR1I2). We revealed, for the first time, significant and heterogeneous expression of PXR in human melanoma samples. We previously showed that PXR can be activated by BRAF inhibitors (BRAFi), but not by MEK inhibitors (MEKi), which are currently used in combination for the treatment of BRAF-V600E-mutated melanoma. Here, we investigated whether PXR expression influences melanoma cell sensitivity to MAPK pathway inhibitors. Using BRAF-mutated human melanoma cell lines, we showed that stable PXR expression sensitizes cells to combined BRAFi/MEKi treatment. Transcriptomic analysis further revealed that PXR expression is associated with the upregulation of several phenotypic markers, with MITF identified as a major regulator in untreated PXR-overexpressing cells. These findings suggest that PXR promotes a shift toward a melanocytic phenotype, which is associated with increased sensitivity to BRAFi/MEKi treatment. Characterization of the PXR-associated transcriptional signature in melanoma may therefore have translational value for identifying patients more likely to benefit from targeted therapies and support the development of PXR as a predictive biomarker of therapeutic response.

cancer biology↗

bioRxiv2026

Characterization of the p38α MAPK allosteric inhibition by a single chain Fv antibody

Most of the available p38 kinase inhibitors target the highly conserved ATP-binding site, thus explaining their off-target effects and toxicity. Here, we report the use of single-chain fragment variable (scFv) antibodies to identify new highly specific inhibitors. Using phage display, we selected five anti-p38 scFv antibodies among which one fully inhibited p38 kinase activity in vitro. We showed that this scFv did not affect ATP binding, while still acting as a competitive inhibitor of ATP hydrolysis. When expressed as intrabody in the nucleus of the THP-1 human monocytic cell line, the scFv inhibited the function of endogenous p38 and induced a significant decrease in lipopolysaccharide-induced tumor necrosis factor production. To gain insight into the mechanisms by which the scFv induced p38 inhibition, the scFv epitope was mapped by deep mutational scanning of p38 displayed on yeast surface and high-throughput selection by flow cytometry of p38 mutants no longer bound by the scFv. By this approach, we showed that the inhibitory scFv interacts with two helices within the C-terminal lobe of the kinase distant from the ATP-binding pocket and the docking groove. Altogether, our data show that the scFv antibody behaves as an allosteric inhibitor, constraining and maintaining p38 in an inactive form.

biochemistry↗

bioRxiv2025

Modulating p38MAPK recalibrates sensitivity of drug-resistant pancreatic adenoductal carcinoma cells toward chemotherapy and correlate with improved outcome in PDAC patients: Experimental and metadata evidence

Pancreatic cancer is one of the deadliest cancers and has very limited therapeutic options and a dismal prognosis. Among various signaling pathways which are activated during tumor development, hyperactivation of Mitogen-Activated Protein Kinase (MAPK) is responsible for high grade angiogenesis, polarization of Tumor Associated Macrophages, unfolded protein responses and exhaustion of T cells, which together contributes towards this therapeutic resistance. We therefore believe that MAPK targeting is expected to enhance sensitivity of highly resistant PDAC cells toward various cancer directed interventions. In this context, we investigated the impact of modulating p38MAPK on the sensitivity of pancreatic cancer cells towards gemcitabine. Supporting our hypothesis, our results convincely, demonstrated that indeed, p38 inhibition sensitizes both KRAS positive Panc-1 and MiaPaCa2 pancreatic carcinoma cells towards gemcitabine induced death. Interestingly p38MAPK targeting significantly reduced the cell viability, clonogenic potential of these cells and enhanced the early apoptosis. Our in-silico studies, supporting our in vitro data, potentially correlated that that high expression of p38 MAPK14 in PDAC patients is associated with poor prognosis and disease free survival. Deep miming of in silico data further demonstrated that MAPK14, in association with, hypoxia inducible factor-1 alpha and vascular endothelial growth factor signaling pathways promote angiogenic programming of PDAC which render these tumors refractory for cancer directed interventions. Based on our preliminary data, we believe that p38 MAPK based approach is potential approach for changing the faith of PDAC patients toward chemo and immunotherapy and believed to improve PDAC burden effectively in the host. HighlightsO_LIp38 MAPK inhibition enhances the sensitivity of KRAS+ pancreatic cancer cells for Gemcitabine C_LIO_LIP38MAPK knockdown cells are sensitive for Gemcitabine induced death C_LIO_LIMAPK14 (p38) is associated with angiogenesis and poor prognosis in pancreatic cancer C_LIO_LIMAPK14 Regulates Pro-Tumorigenic Pathways and immune infiltration in Pancreatic Cancer C_LI

cancer biology↗

bioRxiv2024

TopBP1 biomolecular condensates: a new therapeutic target in advanced-stage colorectal cancer.

In cancer cells, ATR signaling is crucial to tolerate the intrinsically high damage levels that normally block replication fork progression. Assembly of TopBP1, a multifunctional scaffolding protein, into condensates is required to amplify ATR kinase activity to the levels needed to coordinate the DNA damage response and manage DNA replication stress. Many ATR inhibitors are tested for cancer treatment in clinical trials, but their overall effectiveness is oven compromised by the emergence of resistance and toxicities. In this proof-of-concept study, we propose to disrupt the ATR pathway by targeting TopBP1 condensation. First, we screened a molecule-based library using a previously developed optogenetic approach and identified several TopBP1 condensation inhibitors. Amongst them, AZD2858 disrupted TopBP1 assembly induced by the clinically relevant topoisomerase I inhibitor SN-38, thereby inhibiting the ATR/Chk1 signaling pathway. We found that AZD2858 exerted its effects by disrupting TopBP1 self-interaction and binding to ATR in mammalian cells, and by increasing its chromatin recruitment n cell-free Xenopus laevis egg extracts. Moreover, AZD2858 prevented S-phase checkpoint induction by SN-38, leading to increased DNA damage and apoptosis in a colorectal cancer cell line. Lastly, AZD2858 showed synergistic effect in combination with the FOLFIRI chemotherapy regimen in a spheroid model of colorectal cancer. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=110 SRC="FIGDIR/small/612204v3_ufig1.gif" ALT="Figure 1"> View larger version (61K): org.highwire.dtl.DTLVardef@184d016org.highwire.dtl.DTLVardef@7975f4org.highwire.dtl.DTLVardef@2f22f0org.highwire.dtl.DTLVardef@9ecb11_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2023

The Hippo pathway terminal effector TAZ/WWTR1 mediates oxaliplatin sensitivity in HCT116 colon cancer cells

YAP and TAZ, the Hippo pathway terminal transcriptional activators, are frequently upregulated in cancers. In tumor cells, they have been mainly associated with increased tumorigenesis controlling different aspects from cell cycle regulation, stemness, or resistance to chemotherapies. In fewer cases, they have also been shown to oppose cancer progression, including by promoting cell death through the action of the P73/YAP transcriptional complex, in particular after chemotherapeutic drug exposure. Using several colorectal cancer cell lines, we show here that oxaliplatin treatment led to a dramatic core Hippo pathway down-regulation and nuclear accumulation of TAZ. We further show that TAZ was required for the increased sensitivity of HCT116 cells to oxaliplatin, an effect that appeared independent of P73, but which required the nuclear relocalization of TAZ. Accordingly, Verteporfin and CA3, two drugs affecting the activity of YAP and TAZ, showed an antagonistic with oxaliplatin in co-treatments. Our results support thus an early action of TAZ to sensitize cells to oxaliplatin, consistent with a model in which nuclear TAZ in the context of DNA damage and P53 activity pushes cells towards apoptosis.

cancer biology↗

bioRxiv2022

The crosstalk between DNA-PK and cGAS drives tumor immunogenicity

Cytosolic DNAs promote inflammatory responses upon detection by the cyclic GMP-AMP (cGAMP) synthase (cGAS). It has been thus suggested that cGAS downregulation is an immune escape strategy harnessed by tumor cells. Here, we used glioblastoma cells that lack cGAS to question whether alternative DNA detection pathways can promote pro-inflammatory signaling. We show that the DNA-PK DNA repair complex drives cGAS independent inflammatory responses but that its catalytic activity is required for cGAS-dependent cGAMP production and optimal downstream signaling. We further show that the cooperation between DNA-PK and cGAS favors the expression of chemokines that promote macrophage recruitment in the tumor microenvironment, a process that impaired early tumorigenesis but correlated with poor outcome. Thus, our study supports that cGAS-dependent signaling is acquired during tumorigenesis and that cGAS and DNA-PK activities should be analyzed concertedly to predict the impact of strategies aiming to boost tumor immunogenicity.

cancer biology↗