Biology subjects

Del Castillo Velasco-Herrera, M.

Publications and source records attributed to Del Castillo Velasco-Herrera, M..

4 recordsLinked to original sources

bioRxiv2024

Activation of Wnt/β-catenin signalling by mutually exclusive FBXW11 and CTNNB1 hotspot mutations drives salivary gland basal cell adenoma

Wnt signalling must be just right to promote tumour growth. Basal cell adenoma (BCA) and basal cell adenocarcinoma (BCAC) of the salivary gland are rare tumours that can be difficult to distinguish from each other and other salivary gland tumour subtypes. Due to their rarity, the genetic profiles of BCA and BCAC have not been extensively explored. Using whole-exome and transcriptome sequencing of BCA and BCAC cohorts, we identify a novel recurrent FBXW11 missense mutation (p.F517S) in BCA, that was mutually exclusive with the previously reported CTNNB1 p.I35T gain-of-function (GoF) mutation. These driver events collectively accounted for 94% of BCAs. In vitro, mutant FBXW11 had a dominant negative affect, characterised by defective binding to {beta}-catenin and the accumulation of {beta}-catenin in cells. This was consistent with the nuclear expression of {beta}-catenin observed in BCA cases harbouring the FBXW11 p.F517S mutation and activation of the Wnt/{beta}-catenin pathway. The genomic profiles of BCAC were distinct from BCA, with hotspot DICER1 and HRAS mutations and putative driver mutations affecting PI3K/AKT and NF-{kappa}B signalling pathway genes. A single BCAC, which may represent a malignant transformation of BCA, harboured the recurrent FBXW11 mutation. These findings have important implications for the diagnosis and treatment of BCA and BCAC, which, despite histopathologic overlap, may be unrelated entities.

cancer biology↗

bioRxiv2020

PREDICTIVE IMMUNE CHECKPOINT BLOCKADE CLASSIFIERS DISTINGUISHING MONO- VERSUS COMBINATION THERAPY REQUIREMENT

Although high clinical response rates are seen for immune checkpoint blockade (ICB) treatment of metastatic melanomas, both intrinsic and acquired ICB resistance remain considerable clinical challenges1. Combination ICB (anti-PD-1 + anti-CTLA-4) shows improved patient benefit2-5, but is associated with severe adverse events and exceedingly high cost. Therefore, there is a dire need to stratify individual patients for their likelihood of responding to either anti-PD-1 or anti-CTLA-4 monotherapy, or the combination. Since it is conceivable that ICB responses are influenced by both tumor cell-intrinsic and -extrinsic factors6-9, we hypothesized that a predictive genetic classifier ought to mirror both these features. In a panel of patient-derived melanoma xenografts10 (PDX), we noted that cells derived from the human tumor microenvironment (TME) that were co-grafted with the tumor cells were naturally replaced by murine cells after the first passage. Taking advantage of the XenofilteR11 algorithm we recently developed to deconvolute human from murine RNA sequence reads from PDX10, we obtained curated human melanoma tumor cell RNA reads. These expression signals were computationally subtracted from the total RNA profiles in bulk (tumor cell + TME) melanomas from patients. We thus derived one genetic signature that is purely tumor cell-intrinsic ("InTumor"), and one that comprises tumor cell-extrinsic RNA profiles ("ExTumor"). Here we report that the InTumor signature predicts patient response to anti-PD-1, but not anti-CTLA-4 treatment. This was validated in melanoma PDX and cell lines, which confirmed that InTumorLO tumors were effectively eliminated by adoptive cell transfer of T-Cell Receptor (TCR)-matched cytotoxic T cells, whereas InTumorHI melanomas were refractory and grew out as fast as tumors challenged with unmatched T cells. In contrast, the ExTumor signature predicts patient response to anti-CTLA-4 but not anti-PD-1. Most importantly, we used the InTumor and ExTumor signatures in conjunction to generate an ICB response quadrant, which predicts clinical benefit for five independent melanoma patient cohorts treated with either mono- or combination ICB. Specifically, these signatures enable identification of patients who have a much higher chance of responding to the combination treatment than to either monotherapy (p < 0.05), as well as patients who are likely to experience little benefit from receiving anti-CTLA-4 on top of anti-PD-1 (p < 0.05). These signatures may be clinically exploited to distinguish patients who need combined PD-1 + CTLA-4 blockade from those who are likely to benefit from either anti-CTLA-4 or anti-PD-1 monotherapy.

cancer biology↗

bioRxiv2019

Single-cell sequencing reveals a clonal expansion of pro-inflammatory synovial CD8 T cells expressing tissue homing receptors in psoriatic arthritis

Psoriatic arthritis (PsA) is a debilitating immune-mediated inflammatory arthritis of unknown pathogenesis commonly affecting patients with skin psoriasis. We used three complementary single cell approaches to study leukocytes from PsA joints. Mass cytometry (CyTOF) demonstrated marked (>3 fold) expansion of memory CD8 T cells in the joints compared to matched blood. Further exploration of the memory CD8 compartment using both droplet and plate based single cell RNA sequencing of paired alpha and beta chain T cell receptor sequences identified pronounced CD8 T cell clonal expansions within the joints, strongly suggesting antigen driven expansion. These clonotypes exhibited distinct gene expression profiles including cycling, activation, tissue homing and tissue residency markers. Pseudotime analysis of these clonal CD8 populations identified trajectories in which tissue residency can represent an intermediate developmental state giving rise to activated, cycling and exhausted CD8 populations. Comparing T-cell clonality across patients further revealed specificity convergence of clones against a putative common antigen. We identify chemokine receptor CXCR3 as upregulated in expanded synovial clones, and elevation of two CXCR3 ligands, CXCL9 and CXCL10, in PsA synovial fluid.

immunology↗

bioRxiv2017

A screen for combination therapies in BRAF/NRAS wild type melanoma identifies nilotinib plus MEK inhibitor as a synergistic combination

Despite recent therapeutic advances in the management of BRAFV600-mutant melanoma, there is still a compelling need for more effective treatments for patients who developed BRAF/NRAS wild type disease. Since the activity of single targeted agents is limited by innate and acquired resistance, we performed a high-throughput drug screen using 180 drug combinations to generate over 18,000 viability curves, with the aim of identifying agents that synergise to kill BRAF/NRAS wild type melanoma cells. From this screen we observed strong synergy between the tyrosine kinase inhibitor nilotinib and MEK inhibitors and validated this combination in an independent cell line collection. We found that AXL expression was associated with synergy to the nilotinib/MEK inhibitor combination, and that both drugs work in concert to suppress pERK. This finding was supported by genome-wide CRISPR screening which revealed that resistance mechanisms converge on regulators of the MAPK pathway. Finally, we validated the synergy of nilotinib/trametinib combination in vivo using patient-derived xenografts. Our results indicate that a nilotinib/MEK inhibitor combination may represent an effective therapy in BRAF/NRAS wild type melanoma patients.

cancer biology↗