Esophageal squamous cell carcinoma (ESCC), the most frequent esophageal cancer (EC) subtype, entails dismal prognosis. Hypoxia, a common feature of advanced ESCC, is involved in resistance to radiotherapy (RT). RT response in hypoxia might be modulated through epigenetic mechanisms, constituting novel targets to improve patient outcome. Post-translational methylation in histone can be partially modulated by histone lysine demethylases (KDMs), which specifically removes methyl groups in certain lysine residues. KDMs deregulation was associated with tumor aggressiveness and therapy failure. Thus, we sought to unveil the role of Jumonji C domain histone lysine demethylases (JmjC-KDMs) in ESCC radioresistance acquisition. The effectiveness of RT upon ESCC cells under hypoxic conditions was assessed by colony formation assay. KDM3A/KDM6B expression, and respective H3K9me2 and H3K27me3 target marks, were evaluated by RT-qPCR, Western blot, and immunofluorescence. Effect of JmjC-KDM inhibitor IOX1, as well asKDM3Aknockdown, in in vitro functional cell behavior and RT response was assessed in ESCC under hypoxic conditions. In vivo effect of combined IOX1 and ionizing radiation treatment was evaluated in ESCC cells using CAM assay. KDM3A, KDM6B, HIF-1α, and CAIX immunoexpression was assessed in primary ESCC and normal esophagus. Herein, we found that hypoxia promoted ESCC radioresistance through increased KDM3A/KDM6B expression, enhancing cell survival and migration and decreasing DNA damage and apoptosis, in vitro. Exposure to IOX1 reverted these features, increasing ESCC radiosensitivity and decreasing ESCC microtumors size, in vivo. KDM3A was upregulated in ESCC tissues compared to the normal esophagus, associating and colocalizing with hypoxic markers (HIF-1α and CAIX). Therefore, KDM3A upregulation in ESCC cell lines and primary tumors associated with hypoxia, playing a critical role in EC aggressiveness and radioresistance. KDM3A targeting, concomitant with conventional RT, constitutes a promising strategy to improve ESCC patients’ survival.

Background: Renal cell carcinoma (RCC) displays a glycolytic phenotype (Warburg effect). Increased lactate production, impacting on tumor biology and microenvironment modulation, has been implicated in epigenetic mechanisms’ regulation, leading to histone deacetylases inhibition. Thus, in-depth knowledge of lactate’s impact on epigenome regulation of highly glycolytic tumors might allow for new therapeutic strategies. Herein, we investigated how extracellular lactate affected sirtuin 1 activity, a class III histone deacetylase (sirtuins, SIRTs) in RCC. Methods: In vitro and in vivo interactions between lactate and SIRT1 in RCC were investigated in normal kidney and RCC cell lines. Finally, SIRT1 and N-cadherin immunoexpression was assessed in human RCC and normal renal tissues. Results: Lactate inhibited SIRT1 expression in normal kidney and RCC cells, increasing global H3 and H3K9 acetylation. Cells exposed to lactate showed increased cell migration and invasion entailing a mesenchymal phenotype. Treatment with a SIRT1 inhibitor, nicotinamide (NAM), paralleled lactate effects, promoting cell aggressiveness. In contrast, alpha-cyano-4-hydroxycinnamate (CHC), a lactate transporter inhibitor, reversed them by blocking lactate transport. In vivo (chick chorioallantoic membrane (CAM) assay), lactate and NAM exposure were associated with increased tumor size and blood vessel recruitment, whereas CHC displayed the opposite effect. Moreover, primary RCC revealed N-cadherin upregulation whereas SIRT1 expression levels were downregulated compared to normal tissues. Conclusions: In RCC, lactate enhanced aggressiveness and modulated normal kidney cell phenotype, in part through downregulation of SIRT1, unveiling tumor metabolism as a promising therapeutic target.

Esophageal cancer (EC) is the seventh most common cancer worldwide and the sixth leading cause of death, according to Globocan 2018. Despite efforts made for therapeutic advances, EC remains highly lethal, portending a five-year overall survival of just 15–20%. Hence, the discovery of new molecular targets that might improve therapeutic efficacy is urgently needed. Due to high proliferative rates and also the limited oxygen and nutrient diffusion in tumors, the development of hypoxic regions and consequent activation of hypoxia-inducible factors (HIFs) are a common characteristic of solid tumors, including EC. Accordingly, HIF-1α, involved in cell cycle deregulation, apoptosis, angiogenesis induction and proliferation in cancer, constitutes a predictive marker of resistance to radiotherapy (RT). Deregulation of epigenetic mechanisms, including aberrant DNA methylation and histone modifications, have emerged as critical factors in cancer development and progression. Recently, interactions between epigenetic enzymes and HIF-1α transcription factors have been reported. Thus, further insight into hypoxia-induced epigenetic alterations in EC may allow the identification of novel therapeutic targets and predictive biomarkers, impacting on patient survival and quality of life.

Gal-3 plays an important role in cell survival, mRNA splicing, and cell–cell and cell–matrix interactions. Depending on its cellular localization and cancer type, Gal-3 may have tumour-suppressive or tumour-promoting activities. Given the promising diagnostic role of Gal-3 in the urine of PCa patients found in our previous study, its concordant gene and protein expression levels, and its involvement in PCa-related biological processes (e.g., morphogenesis of the prostate gland epithelium), we aimed to investigate this protein immunohistochemically in tumour and normal prostate tissues. Gal-3 protein expression was evaluated in 48 tumour prostate tissues, eight normal prostate tissues and 14 adjacent-normal prostate tissues. Decreased Gal-3 staining was detected in tumour tissues compared with normal tissues. Although Gal-3 staining was decreased in tumour tissues with GS 5-8 and pT2 and pT3 stages compared with normal prostate tissue, no correlation was found between Gal-3 expression and PCa progression. In the present study, the pattern of cellular localization differed between groups, as Gal-3 was predominantly excluded from the nucleus in tumour tissues. Furthermore, Gal-3 had no significant effect on survival and relapse in these PCa patients. This work confirms Gal-3 as a promising marker for PCa diagnosis.

Rectal cancer (RC) incidence is rapidly increasing, with over 50% of cases diagnosed at an advanced stage. Neoadjuvant radiotherapy (RT) is a key treatment, however, 20 to 40% of patients harboring rectal tumors have partial or no response to RT. Progress in understanding radioresistance has been hindered, especially by the limited availability of relevant in vitro models. We developed two high-throughput 3D spheroid models of RC using SW837 and SW1463 cell lines, optimized for reproducibility. The models were evaluated for 3D dynamics, tumor-like features, cell viability and proliferation, and response to a short course RT regimen of 5 Gray during 5 consecutive days, further dissected by assessing ATP levels, cell cycle, gene expression and metabolic activity. Both models exhibited distinct structural and functional features. Upon irradiation, SW837 spheroids displayed a necrotic core and suppressed ATP levels, maintaining peripheral Ki-67 expression, while SW1463 spheroids showed increased cell death levels. Importantly, the models showed distinct sensitivity to RT, as confirmed by the higher radioresistance in SW837 spheroids. Metabolomic profiling revealed that when irradiated, SW837 spheroids held increased levels of glutamate and citrate, while SW1463 spheroids presented significant consumption of metabolites linked to amino-acid pathways. Transcriptomic analysis revealed up-regulation of immunosuppressive pathways and cell cycle arrest genes in SW837 spheroids post-RT. This was supported by an accumulation of cells at G₂M state, while the SW1463 TS model presented more cells accumulated at S-phase. The RC spheroid models herein investigated represent valuable tools for dissecting differential metabolic and transcriptional adaptations to RT and reveal potential targets for battling RC radioresistance. Additionally, the two models display distinct phenotypes and responses support their use in pre-clinical studies, including screening and mechanistic studies in RC.

Patient‐derived organoids (PDO) are accelerating precision medicine. These biological platforms allow for the autologous in vitro expansion of material from cancer patients in a considerably short period of time. These three‐dimensional models can faithfully recapitulate aspects of tissue heterogeneity, architecture, and relevant cellular functions. Based on these characteristics, there has been a growing interest in exploring the potential of these models for translational research, as is the case with colorectal, pancreatic, prostate, breast, lung, and bladder cancer, among other solid tumors. A key application of cancer‐specific organoids is the development of patient‐matched platforms for drug testing, thus bringing the hype of personalized medicine closer to clinical practice. Over the past decade, clinical trials based on organoid‐guided drug screening have been conducted in several cancer models with promising results. Nonetheless, further progress is still needed in this field, as there are still few studies that rigorously apply the results of real‐time PDO tests to assist in clinical decision‐making. In this review, we provide a focused synthesis of the most relevant clinical trials using PDO as well as their application for biobanking.