Raúl Navaridas

Overnutrition-related liver dysfunction and cancer are increasingly prevalent and highly resistant to immunotherapy. While metabolic dysregulation is a hallmark of hepatocellular carcinoma (HCC), how nutrient overload impairs antitumor immunity remains unclear. Here, we show that short-term Western diet (WD) exposure drives near-complete loss of CD8⁺ T cell infiltration and antitumor function in HCC. We identify dietary linoleic acid (LA), the most abundant ω-6 fatty acid, as the dominant immunosuppressive driver. Cancer cell-restricted FADS2-mediated desaturation of LA to longer-chain ω-6 PUFAs drives their accumulation in the tumor interstitial fluid, suppressing infiltrating CD8⁺ T cells via lipid peroxidation. FADS2 inhibition restores CD8⁺ T cell function and sensitizes WD-driven HCC to PD-1-based immunotherapy. Further, the Parkinson's disease-associated deglycase DJ-1 protects LA-handling proteins from methylglyoxal-mediated glycation, sustaining tumoral immunosuppressive PUFA production. Across multiple independent human MASLD-HCC cohorts, LA metabolic activity correlates with CD8⁺ T cell impairment, immune exclusion, and immunotherapy resistance. Overall, these studies identify a dietary lipid axis as a therapeutically actionable vulnerability in WD-associated HCC.

Colorectal cancer (CRC) is a leading cause of cancer-related morbidity and mortality worldwide, with molecular subtypes and signaling pathways playing critical roles in its progression. The miR-424(322) ^~ 503 cluster, comprising miR-424 and miR-503, has been implicated in various malignancies, exhibiting dual roles as tumor suppressors or oncogenes depending on the context. However, its function in CRC remains poorly understood. This study investigates the role of the miR-424(322) ^~ 503 cluster in CRC driven by PTEN deficiency using genetically modified mouse models. Our findings reveal that the loss of miR-424(322) ^~ 503 significantly exacerbates CRC progression in PTEN-deficient mice. Double knockout (dKO) mice lacking both PTEN and miR-424(322) ^~ 503 exhibited a higher number and larger size of colorectal lesions compared to PTEN-deficient counterparts. Histological analysis demonstrated increased severity of dysplasia and adenocarcinoma development in dKO mice. Mechanistically, while Wnt/β-catenin signaling remained unaltered, transcriptomic analyses highlighted dysregulation of MAPK and TGFβ pathways, alongside epithelial-to-mesenchymal transition (EMT)-related gene signatures. Protein-level validation confirmed hyperactivation of MAPK (ERK1/2 and p38) and TGFβ signaling, as well as elevated cyclin D1 expression in dKO colonic tissues. These results underscore the tumor-suppressive role of the miR-424(322) ^~ 503 cluster in CRC by modulating key oncogenic pathways such as MAPK and TGFβ. Our study provides novel insights into the interplay between PTEN loss and miRNA regulation in CRC pathogenesis.

Endometrial cancer is the most frequent type of cancer in the female reproductive tract. Loss-of-function alterations in PTEN, leading to enhanced PI3K/AKT activation, are among the most frequent molecular alterations in endometrial cancer. Increased PI3K/AKT signaling resulting from PTEN loss promotes cellular proliferation and confers resistance to TGFβ-mediated apoptosis, a key regulator of endometrial homeostasis. In this study, we have analyzed the role of miRNAs in driving these altered cellular responses. A comprehensive transcriptomic analysis of miRNA expression revealed the upregulation of several miRNAs caused by PTEN deficiency and/or TGFβ stimulation. The miR-424(322)^~503 cluster drew our attention due to its involvement in regulating apoptosis and proliferation. However, miR-424(322)^~503 cluster has a paradoxical role in cancer, exhibiting either oncogenic and tumor suppressive functions depending on cell type or context. To ascertain the function of miR-424(322)^~503 in endometrial carcinogenesis caused by PTEN deficiency, we generated a double Pten/miR-424(322)^~503 knock-out mice. We demonstrate that loss of miR-424(322)^~503 impairs proliferation of both wild type or Pten deficient endometrial organoids by interfering with growth factor and PI3K/AKT signaling. Furthermore, the absence of miR-424(322)^~503 restores TGFβ-induced apoptosis, which is otherwise compromised by PTEN deficiency. In vivo, Pten/miR-424(322)^~503 knock-out mice exhibit reduced endometrial cancer progression compared to Pten deficient mice through a cell-autonomous mechanism.

Genes of the Sprouty family (Spry1-4) are feedback inhibitors of receptor tyrosine kinases, especially of Ret and the FGF receptors. As such, they play distinct and overlapping roles in embryo morphogenesis and are considered to be tumor suppressors in adult life. Genetic experiments in mice have defined in great detail the role of these genes during embryonic development, however their function in adult mice is less clearly established. Here we generate adult-onset, whole body Spry1/2/4 triple knockout mice. Tumor incidence in triple mutant mice is comparable to that of wild type littermates of up to one year of age, indicating that Sprouty loss per se is not sufficient to initiate tumorigenesis. On the other hand, triple knockout mice do not gain weight as they age, show less visceral fat, and have lower plasma glucose levels than wild type littermates, despite showing similar food intake and slightly reduced motor function. They also show alopecia, eyelid inflammation, and mild hyperthyroidism. Finally, triple knockout mice present phosphaturia and hypophosphatemia, suggesting exacerbated signaling downstream of FGF23. In conclusion, triple knockout mice develop a series of endocrine abnormalities but do not show increased tumor incidence.

Phosphatase and TENsin homolog (Pten) and p53 are two of the most frequently mutated tumor suppressor genes in endometrial cancer. However, the functional consequences and histopathological manifestation of concomitant p53 and Pten loss of function alterations in the development of endometrial cancer is still controversial. Here, it is demonstrated that simultaneous Pten and p53 deletion is sufficient to cause epithelial to mesenchymal transition phenotype in endometrial organoids. By a novel intravaginal delivery method using HIV1 trans‐activator of transcription cell penetrating peptide fused with a Cre recombinase protein (TAT‐Cre), local ablation of both p53 and Pten is achieved specifically in the uterus. These mice developed high‐grade endometrial carcinomas and a high percentage of uterine carcinosarcomas resembling those found in humans. To further demonstrate that carcinosarcomas arise from epithelium, double Pten/p53 deficient epithelial cells are mixed with wild type stromal and myometrial cells and subcutaneously transplanted to Scid mice. All xenotransplants resulted in the development of uterine carcinosarcomas displaying high nuclear pleomorphism and metastatic potential. Accordingly, in vivo CRISPR/Cas9 disruption of Pten and p53 also triggered the development of metastatic carcinosarcomas. The results unfadingly demonstrate that simultaneous deletion of p53 and Pten in endometrial epithelial cells is enough to trigger epithelial to mesenchymal transition that is consistently translated to the formation of uterine carcinosarcomas in vivo.

Netrin-1 is upregulated in cancers as a protumoural mechanism¹. Here we describe netrin-1 upregulation in a majority of human endometrial carcinomas (ECs) and demonstrate that netrin-1 blockade, using an anti-netrin-1 antibody (NP137), is effective in reduction of tumour progression in an EC mouse model. We next examined the efficacy of NP137, as a first-in-class single agent, in a Phase I trial comprising 14 patients with advanced EC. As best response we observed 8 stable disease (8 out of 14, 57.1%) and 1 objective response as RECIST v.1.1 (partial response, 1 out of 14 (7.1%), 51.16% reduction in target lesions at 6 weeks and up to 54.65% reduction during the following 6 months). To evaluate the NP137 mechanism of action, mouse tumour gene profiling was performed, and we observed, in addition to cell death induction, that NP137 inhibited epithelial-to-mesenchymal transition (EMT). By performing bulk RNA sequencing (RNA-seq), spatial transcriptomics and single-cell RNA-seq on paired pre- and on-treatment biopsies from patients with EC from the NP137 trial, we noted a net reduction in tumour EMT. This was associated with changes in immune infiltrate and increased interactions between cancer cells and the tumour microenvironment. Given the importance of EMT in resistance to current standards of care², we show in the EC mouse model that a combination of NP137 with carboplatin-paclitaxel outperformed carboplatin-paclitaxel alone. Our results identify netrin-1 blockade as a clinical strategy triggering both tumour debulking and EMT inhibition, thus potentially alleviating resistance to standard treatments.

Glioblastoma (GBM) is the most common tumor in the central nervous system in adults. This neoplasia shows a high capacity of growth and spreading to the surrounding brain tissue, hindering its complete surgical resection. Therefore, the finding of new antitumor therapies for GBM treatment is a priority. We have previously described that cyclin D1-CDK4 promotes GBM dissemination through the activation of the small GTPases RalA and RalB. In this paper, we show that RalB GTPase is upregulated in primary GBM cells. We found that the downregulation of Ral GTPases, mainly RalB, prevents the proliferation of primary GBM cells and triggers a senescence-like response. Moreover, downregulation of RalA and RalB reduces the viability of GBM cells growing as tumorspheres, suggesting a possible role of these GTPases in the survival of GBM stem cells. By using mouse subcutaneous xenografts, we have corroborated the role of RalB in GBM growth in vivo. Finally, we have observed that the knockdown of RalB also inhibits cell growth in temozolomide-resistant GBM cells. Overall, our work shows that GBM cells are especially sensitive to Ral-GTPase availability. Therefore, we propose that the inactivation of Ral-GTPases may be a reliable therapeutic approach to prevent GBM progression and recurrence.

Background Disseminated BRAF^V600E melanoma responds to BRAF inhibitors (BRAFi) but easily develops resistance with poor prognosis. Secretome plays a pivotal role during tumour progression causing profound effects on therapeutic efficacy. Secreted M-CSF is involved in both cytotoxicity suppression and tumour progression in melanoma. We aimed to analyse the M-CSF contribution in resistant metastatic melanoma to BRAF-targeted therapies. Methods Conditioned media from melanoma cells were analysed by citoarray. Viability and migration/invasion assays were performed with paired melanoma cells and tumour growth in xenografted SCID mice. We evaluated the impact of M-CSF plasma levels with clinical prognosis from 35 metastatic BRAF^V600E-mutant melanoma patients. Results BRAFi-resistant melanoma cells secretome is rich in pro-tumour cytokines. M-CSF secretion is essential to induce a Vemurafenib-resistant phenotype in melanoma cells. Further, we demonstrated that M-CSF mAb in combination with Vemurafenib and autophagy blockers synergistically induce apoptosis, impair migration and reduce tumour growth in BRAFi-resistant melanoma cells. Interestingly, lower M-CSF plasma levels are associated with better prognosis in metastatic melanoma patients. Conclusions Secreted M-CSF induces a BRAFi-resistant phenotype and means worse prognosis in BRAF^V600E metastatic melanoma patients. These results identify secreted M-CSF as a promising therapeutic target toward BRAFi-resistant melanomas.

TGF-β has a dichotomous function, acting as tumor suppressor in premalignant cells but as a tumor promoter for cancerous cells. These contradictory functions of TGF-β are caused by different cellular contexts, including both intracellular and environmental determinants. The TGF-β/SMAD and the PI3K/PTEN/AKT signal transduction pathways have an important role in the regulation of epithelial cell homeostasis and perturbations in either of these two pathways’ contributions to endometrial carcinogenesis. We have previously demonstrated that both PTEN and SMAD2/3 display tumor-suppressive functions in the endometrium, and genetic ablation of either gene results in sustained activation of PI3K/AKT signaling that suppresses TGF-β-induced apoptosis and enhances cell proliferation of mouse endometrial cells. However, the molecular and cellular effects of PTEN deficiency on TGF-β/SMAD2/3 signaling remain controversial. Here, using an in vitro and in vivo model of endometrial carcinogenesis, we have demonstrated that loss of PTEN leads to a constitutive SMAD2/3 nuclear translocation. To ascertain the function of nuclear SMAD2/3 downstream of PTEN deficiency, we analyzed the effects of double deletion PTEN and SMAD2/3 in mouse endometrial organoids. Double PTEN/SMAD2/3 ablation results in a further increase of cell proliferation and enlarged endometrial organoids compared to those harboring single PTEN, suggesting that nuclear translocation of SMAD2/3 constrains tumorigenesis induced by PTEN deficiency.

EndoG influences mitochondrial DNA replication and is involved in somatic cell proliferation. Here, we investigated the effect of ENDOG/Endog expression on proliferation in different tumor models. Noteworthy, ENDOG deficiency reduced proliferation of endometrial tumor cells expressing low PTEN/high p-AKT levels, and Endog deletion blunted the growth of PTEN-deficient 3D endometrial cultures. Furthermore, ENDOG silencing reduced proliferation of follicular thyroid carcinoma and glioblastoma cell lines with high p-AKT expression. High ENDOG expression was associated with a short time to treatment in a cohort of patients with chronic lymphocytic leukemia (CLL), a B-cell lymphoid neoplasm with activation of PI3K/AKT. This clinical impact was observed in the less aggressive CLL subtype with mutated IGHV in which high ENDOG and low PTEN levels were associated with worse outcome. In summary, our results show that reducing ENDOG expression hinders growth of some tumors characterized by low PTEN activity and high p-AKT expression and that ENDOG has prognostic value for some cancer types.