Biology subjects

Palomero, L.

Publications and source records attributed to Palomero, L..

4 recordsLinked to original sources

bioRxiv2021

Mammary lineage dictates homologous recombination repair and PARP inhibitor vulnerability

It has long been assumed that all normal cells have the same capacity to engage homologous recombination (HR) and non-homologous end joining (NHEJ) to repair DNA double-strand breaks (DSBs), a concept exploited for DNA-damaging chemotherapeutics. We show that mammary epithelial lineage dictates the DSB repair pathway choice. Primary mammary proteomes and DSB repair enumeration by {gamma}-H2AX, Rad51 and DNA-PKc foci reveal that NHEJ operates in all epithelial cells, but high-fidelity HR is restricted to the luminal lineage. This translates to divergent poly (ADP-ribose) polymerase inhibitor (PARPi) vulnerability of mammary epithelial progenitor activity in both mouse and human, irrespective of the BRCA1/2 status. Proteome-defined lineage-specific signatures correlate to breast cancer subtypes and predict PARPi response of triple-negative human breast cancer xenografts. These intrinsically divergent HR characteristics of mammary cell types underpin a new strategy for identifying PARPi responders.

cancer biology↗

bioRxiv2020

Taxane induces attenuation of the CXCR2/BCL-2 axis and sensitize prostate cancer to platinum-based treatments

BackgroundTaxanes are the most active chemotherapy agents in metastatic castration resistant prostate cancer (mCRPC) patients, yet resistance almost invariably occurs representing an important clinical challenge. Taxane-platinum combinations have shown clinical benefit in a subset of patients but the mechanistic basis and biomarkers remain elusive. ObjectiveTo identify mechanisms and response biomarkers for the antitumor efficacy of taxane-platinum combinations in mCRPC. Design, setting, and participantsTranscriptomic data from a publicly available mCRPC dataset of taxane-exposed and naive patients was analysed to identify response biomarkers and emerging vulnerabilities. Functional and preclinical validation was performed in taxane resistant mCRPC cell lines and genetically engineered mouse models (GEMM). InterventionmCRPC cells were treated with docetaxel, cisplatin, carboplatin and the CXCR2 inhibitor, SB265610. Gain and loss of function in culture of CXCR2 was achieved by overexpression or siRNA-silencing. Preclinical assays in GEMM mice tested the anti-tumor efficacy of taxane-platinum combinations. Outcome measurements and statistical analysisProliferation, apoptosis and colony assays measured drug activity in vitro. Preclinical endpoints in mice included growth, survival and histopathology. Changes in CXCR2, BCL-2 and chemokines were analysed by RT-qPCR and Western Blot. Human expression data was analyzed using GSEA, hierarchical clustering and correlation studies. GraphPad Prism software, R-studio, were used for statistical and data analyses. Results and limitationsTranscriptomic data from taxane-exposed human mCRPC tumors correlates with a marked negative enrichment of apoptosis and inflammatory response pathways accompanied by a marked downregulation of CXCR2 and BCL-2. Mechanistically, we show that docetaxel treatment inhibits CXCR2 and that BCL-2 downregulation occurs as a downstream effect. Further, we demonstrated that taxane resistance is directly associated to CXCR2 expression and that targeting of CXCR2 sensitizes prostate cancer (PC) cells to cisplatin. Finally, taxane-platinum combinations in vivo are highly synergistic and previous exposure to taxanes sensitizes mCRPC tumors to second line cisplatin treatment. ConclusionsTogether our data identifies an acquired vulnerability in taxane treated mCRPC patients with potential predictive activity for platinum-based treatments. Patient summaryA subset of patients with aggressive and therapy resistant PC benefits from taxane-platinum combination chemotherapy however, we lack biomarkers and mechanistic basis about how that synergistic effect occurs. Here, using patient data and preclinical models, we found that taxanes reduce cancer cell scape mechanisms to chemotherapy-induced cell death, hence turning these cells more vulnerable to additional platinum treatment.

cancer biology↗

bioRxiv2019

Mammary epithelial cells have lineage-restricted metabolic identities

Cancer metabolism adapts the metabolic network of its tissue-of-origin. However, breast cancer is not a disease of a singular origin. Multiple epithelial populations serve as the culprit cell-of-origin for specific breast cancer subtypes, yet knowledge surrounding the metabolic network of normal mammary epithelial cells is limited. Here, we show that mammary populations have cell type-specific metabolic programs. Primary human breast cell proteomes of basal, luminal progenitor, and mature luminal populations revealed their unique enrichment of metabolic proteins. Luminal progenitors had higher abundance of electron transport chain subunits and capacity for oxidative phosphorylation, whereas basal cells were more glycolytic. Targeting oxidative phosphorylation and glycolysis with inhibitors exposed distinct metabolic vulnerabilities of the mammary lineages. Computational analysis indicated that breast cancer subtypes retain metabolic features of their putative cell-of-origin. Lineage-restricted metabolic identities of normal mammary cells partly explain breast cancer metabolic heterogeneity and rationalize targeting subtype-specific metabolic vulnerabilities to advance breast cancer therapy.

cell biology↗

bioRxiv2018

Subjugation of TGFβ Signaling by Human Papilloma Virus in Head and Neck Squamous Cell Carcinoma Shifts DNA Repair from Homologous Recombination to Alternative End-Joining

Purpose: Following cytotoxic therapy, 70% of patients with human papillomavirus (HPV) positive oropharyngeal head and neck squamous cell carcinoma (HNSCC) are alive at 5 years compared to 30% of those with similar HPV-negative cancer, which is thought to be due to dysregulation of DNA repair. Loss of transforming growth factor {beta} (TGF{beta}) signaling is a poorly studied consequence of HPV that could contribute to this phenotype.\n\nExperimental Design: Human HNSCC cell lines (n=9), patient-derived xenografts (n=9), tissue microarray (n=194), TCGA expression data and primary tumor specimens (n=10) were used to define the relationship between TGF{beta} competency, response to DNA damage, and type of DNA repair.\n\nResults: Analysis of HNSCC specimens in situ and in vitro showed that HPV associates with loss of TGF{beta} signaling that increases the response to radiation or cisplatin. TGF{beta} suppressed miR-182 that inhibited both BRCA1, necessary for homologous recombination repair, and FOXO3, which is required for ATM kinase activity. TGF{beta} signaling blockade by either HPV or inhibitors released this control, compromised HRR and increased response to PARP inhibition. Antagonizing miR-182 rescued the homologous recombination deficit in HPV+ cells. Loss of TGF{beta} signaling unexpectedly increased error-prone, alternative end-joining repair.\n\nConclusions: HPV-positive HNSCC cells are unresponsive to TGF{beta}. Abrogated TGF{beta} signaling compromises homologous recombination and shifts reliance on alt-EJ repair that provides a mechanistic basis for sensitivity to PARP inhibitors. The effect of HPV in HNSCC provides critical validation of TGF{beta}s role in DNA repair proficiency and further raises the translational potential of TGF{beta} inhibitors in cancer therapy.

cancer biology↗