Víctor González-Ruiz

Background: Testicular germ cell tumors (TGCTs) are the most common malignancy in young adult men, and the development of reliable non‐invasive diagnostic tools remains a clinical priority. Seminal plasma is a complex yet accessible biofluid that reflects the function of the male reproductive system and may capture metabolic alterations associated with testicular pathology. Objectives: This study aimed to characterize the seminal plasma metabolome of TGCT patients using a multi‐platform metabolomics strategy that covers polar metabolites and oxylipins. Materials and Methods: Seminal plasma from 37 TGCT patients and 11 non‐TGCT clinical controls was analyzed by capillary electrophoresis‐mass spectrometry (CE‐MS) and oxylipin profiling using liquid chromatography coupled to tandem mass spectrometry (LC‐MS/MS). Immunohistochemical analysis of testicular tumor tissue was used to confirm enzymatic expression degree. Results: CE‐MS revealed coordinated alterations in polar metabolites, particularly many involved in energy metabolism, suggesting a disruption of testicular metabolic homeostasis in TGCTs. Reduced levels of key energy‐related amino acids in plasma suggested increased metabolic demand in tumor cells, consistent with altered biosynthetic and redox pathways. Additional changes in hexosamine pathway metabolites indicated potential alterations in protein glycosylation and secretory activity. Oxylipin profiling using targeted LC‐MS/MS identified several lipid mediators with significant differences between groups. Four compounds (9,10‐DiHOME, 6‐ trans ‐LTB ₄ , TXB ₂ , and 14,15‐DiHETrE) were elevated in TGCT samples and demonstrated discriminatory potential in univariate analyses. A composite oxylipin ratio of these compounds achieved excellent diagnostic performance, indicating that oxylipin‐based signatures may support TGCT detection. Immunohistochemical staining confirmed arachidonate 12‐lipoxygenase (ALOX12) expression in tumor tissue, confirming biological plausibility for the observed oxylipin alterations. Discussion and Conclusion: Seminal plasma carries detectable metabolic signatures of TGCT, encompassing alterations in energy metabolism and inflammation‐related lipid mediators. These findings establish a foundation for developing non‐invasive metabolomic biomarkers for TGCT and warrant validation in larger and independent cohorts.

Infection with high-risk Human papillomavirus (HR-HPV), is the main etiological factor in the development of cervical cancer (CC), but the complex and interconnected molecular mechanisms driving its progression remain incompletely understood. In this context, metabolomics has emerged as a powerful tool for the identification of disease-specific metabolic alterations and the discovery of potential diagnostic and prognostic biomarkers. This systematic review compiles and analyzes findings from 17 human-based metabolomics studies on HPV infection, covering various stages of cervical disease, ranging from asymptomatic infection to low- and high-grade squamous intraepithelial lesions (LSIL and HSIL) and invasive cervical cancer (ICC). Mass spectrometry (MS) approaches have revealed key metabolites and altered pathways involving amino acid, lipid, and energy metabolism. Notably, several high-performing biomarkers (AUC > 0.9) have been identified in non-invasive samples such as cervical mucus and urine, highlighting their clinical potential. Moreover, recent integrative multi-omics studies incorporating metagenomic data have revealed a critical interplay between HPV, host metabolism, and the cervicovaginal microbiota, in which Lactobacillus depletion and microbial dysbiosis contribute to inflammation and oxidative stress, thereby promoting HPV persistence and disease progression. These findings support the inclusion of metabolomics in early diagnostic screening and suggest new therapeutic strategies targeting redox balance, lipid biosynthesis, and amino acid pathways. Future research should aim to validate these biomarkers in larger cohorts and explore microbiota-modulating interventions as potential preventive strategies.

Selective targeting of cancer cells is a major challenge for cancer therapy. Many cancer cells overexpress the cystine/glutamate antiporter xCT/CD98, an l-cystine transport system that strengthens antioxidant defences, thereby promoting tumour survival and progression. Here, we show that the d-enantiomer of cysteine (d-Cys) is selectively imported into xCT/CD98-overexpressing cancer cell lines and impairs their proliferation, particularly under high oxygen concentrations. Intracellular d-Cys specifically inhibits the mitochondrial cysteine desulfurase NFS1, a key enzyme of cellular iron–sulfur protein biogenesis, by blocking sulfur mobilization due to steric constraints. NFS1 inhibition by d-Cys affects all cellular iron–sulfur cluster-dependent functions, including mitochondrial respiration, nucleotide metabolism and maintenance of genome integrity, leading to decreased oxygen consumption, DNA damage and cell cycle arrest. d-Cys administration diminishes tumour growth of human triple-negative breast cancer cells implanted orthotopically into the mouse mammary gland. Hence, d-Cys could represent a simple therapy to selectively target those forms of cancer characterized by overexpression of xCT/CD98.

Although immune-based therapies have revolutionized the management of cancer, novel approaches are urgently needed to improve their outcome. We investigated the role of endogenous steroids in the resistance to cancer immunotherapy, as these have strong immunomodulatory functions. Using a publicly available database, we found that the intratumoral expression of 11 beta-hydroxysteroid dehydrogenase type 1 (HSD11B1), which regenerates inactive glucocorticoids into active glucocorticoids, was associated with poor clinical outcome and correlated with immunosuppressive gene signatures in patients with renal cell carcinoma (RCC). HSD11B1 was mainly expressed in tumor-infiltrating immune myeloid cells as seen by immunohistochemistry in RCC patient samples. Using peripheral blood mononuclear cells from healthy donors or immune cells isolated from the tumor of RCC patients, we showed that the pharmacological inhibition of HSD11B1 improved the response to the immune checkpoint inhibitor anti-PD-1. In a subcutaneous mouse model of renal cancer, the combination of an HSD11B1 inhibitor with anti-PD-1 treatment increased the proportion of tumor-infiltrating dendritic cells. In an intrarenal mouse tumor model, HSD11B1 inhibition increased the survival of mice treated with anti-PD-1. In addition, inhibition of HSD11B1 sensitized renal tumors in mice to immunotherapy with resiquimod, a Toll-like receptor 7 agonist. Mechanistically, we demonstrated that HSD11B1 inhibition combined with resiquimod increased T cell-mediated cytotoxicity to tumor cells by stimulating the antigen-presenting capacity of dendritic cells. In conclusion, these results support the use of HSD11B1 inhibitors to improve the outcome of immunotherapy in renal cancer and highlight the role of the endogenous glucocorticoid metabolism in the efficacy of immunotherapy.

Selective targeting of cancer cells is a major challenge for cancer therapy. Many cancer cells overexpress the cystine/glutamate antiporter xCT/CD98 to increase the import of L-cystine for antioxidant defense, thus supporting tumour cell survival and progression^_1,2. We have exploited this feature of cancer cells by transforming xCT/CD98 overexpression into a selective vulnerability. We found that the D-enantiomer of cysteine (Cys), but not other D-amino acids, impaired proliferation of numerous xCT/CD98-expressing cancer cell lines, whereas xCT/CD98-non-overexpressing (cancer) cells were unaffected. D-Cys acquired by xCT/CD98 specifically inhibited the cysteine desulfurase NFS1, the sulfur donor of cellular iron-sulfur protein biogenesis³. NFS1 was able to form the D-Cys-ketimine intermediate, but, due to steric incompatibility, failed to transfer the D-Cys sulfur to its active-site Cys381 residue, thereby blocking enzymatic activity. This led to a general defect of all cellular processes relying on iron-sulfur proteins, including mitochondrial respiration, nucleotide metabolism, and nuclear genome maintenance, resulting in reduced oxygen consumption, accumulation of DNA damage, and cell cycle arrest. In vivo D-Cys administration diminished tumour growth of human triple-negative breast cancer cells implanted orthotopically into the mouse mammary gland. Hence, D-Cys could represent a simple therapy to selectively target those forms of cancer characterized by overexpression of xCT/CD98.