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Cystic fibrosis (CF) is caused by defects of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. CFTR-modulating drugs may overcome specific defects, such as the case of Trikafta, which is a clinically approved triple combination of Elexacaftor, Tezacaftor and Ivacaftor (ETI) that exhibited a strong ability to rescue the function of the most frequent F508del pathogenic variant even in genotypes with the mutated allele in single copy. Nevertheless, most rare genotypes lacking the F508del allele are still not eligible for targeted therapies. Via the innovative approach of using nasal conditionally reprogrammed cell (CRC) cell-based models that mimic patient disease in vitro , which are obtainable from each patient due to the 100% efficiency of the cell culture establishment, we theratyped orphan CFTR mutation L1077P. Protein studies, Forskolin-induced organoid swelling, and Ussing chamber assays congruently proved the L1077P variant function rescue by ETI. Notably, this rescue takes place even in the context of a single-copy L1077P allele, which appears to enhance its expression. Thus, the possibility of single-allele treatment also arises for rare genotypes, with an allele-specific modulation as part of the mechanism. Of note, besides providing indication of drug efficacy with respect to specific CFTR pathogenic variants or genotypes, this approach allows the evaluation of the response of single-patient cells within their genetic background. In this view, our studies support in vitro guided personalized CF therapies also for rare patients who are nearly excluded from clinical trials.

Background Glioblastoma (GBM) is the most common and aggressive primary malignant brain tumor in adults, characterized by a poor prognosis mainly due to recurrence and therapeutic resistance. It has been widely demonstrated that glioblastoma stem-like cells (GSCs), a subpopulation of tumor cells endowed with stem-like properties is responsible for tumor maintenance and progression. Moreover, it has been demonstrated that GSCs contribute to GBM-associated neovascularization processes, through different mechanisms including the transdifferentiation into GSC-derived endothelial cells (GdECs). Methods In order to identify druggable cancer-related pathways in GBM, we assessed the effect of a selection of 349 compounds on both GSCs and GdECs and we selected elesclomol (STA-4783) as the most effective agent in inducing cell death on both GSC and GdEC lines tested. Results Elesclomol has been already described to be a potent oxidative stress inducer. In depth investigation of the molecular mechanisms underlying GSC and GdEC response to elesclomol, confirmed that this compound induces a strong increase in mitochondrial reactive oxygen species (ROS) in both GSCs and GdECs ultimately leading to a non-apoptotic copper-dependent cell death. Moreover, combined in vitro treatment with elesclomol and the alkylating agent temozolomide (TMZ) enhanced the cytotoxicity compared to TMZ alone. Finally, we used our experimental model of mouse brain xenografts to test the combination of elesclomol and TMZ and confirmed their efficacy in vivo. Conclusions Our results support further evaluation of therapeutics targeting oxidative stress such as elesclomol with the aim of satisfying the high unmet medical need in the management of GBM.

Cancer stem cells Two papers in this issue report the identification of a specific type of colon cancer cell that initiates tumour growth in mice. This lends support to the theory that only a few cells within a tumour, the cancer stem cells, are responsible for tumour formation and maintenance. The finding highlights the importance of finding therapeutics to target cancer stem cells. Colon carcinoma is the second most common cause of death from cancer 1 . The isolation and characterization of tumorigenic colon cancer cells may help to devise novel diagnostic and therapeutic procedures. Although there is increasing evidence that a rare population of undifferentiated cells is responsible for tumour formation and maintenance 2 , 3 , 4 , this has not been explored for colorectal cancer. Here, we show that tumorigenic cells in colon cancer are included in the high-density CD133 + population, which accounts for about 2.5% of the tumour cells. Subcutaneous injection of colon cancer CD133 + cells readily reproduced the original tumour in immunodeficient mice, whereas CD133 - cells did not form tumours. Such tumours were serially transplanted for several generations, in each of which we observed progressively faster tumour growth without significant phenotypic alterations. Unlike CD133 - cells, CD133 + colon cancer cells grew exponentially for more than one year in vitro as undifferentiated tumour spheres in serum-free medium, maintaining the ability to engraft and reproduce the same morphological and antigenic pattern of the original tumour. We conclude that colorectal cancer is created and propagated by a small number of undifferentiated tumorigenic CD133 + cells, which should therefore be the target of future therapies.

Two microRNAs, miR-15a and miR-16, localize to a chromosome region that is frequently deleted in cancer. Bonci et al . now show that these microRNAs have tumor suppressive effects in prostate cancer cells and regulate the expression of crucial oncogenic targets. MicroRNAs (miRNAs) are noncoding small RNAs that repress protein translation by targeting specific messenger RNAs. miR-15a and miR-16-1 act as putative tumor suppressors by targeting the oncogene BCL2 . These miRNAs form a cluster at the chromosomal region 13q14, which is frequently deleted in cancer. Here, we report that the miR-15a and miR-16-1 cluster targets CCND1 (encoding cyclin D1) and WNT3A , which promotes several tumorigenic features such as survival, proliferation and invasion. In cancer cells of advanced prostate tumors, the miR-15a and miR-16 level is significantly decreased, whereas the expression of BCL2, CCND1 and WNT3A is inversely upregulated. Delivery of antagomirs specific for miR-15a and miR-16 to normal mouse prostate results in marked hyperplasia, and knockdown of miR-15a and miR-16 promotes survival, proliferation and invasiveness of untransformed prostate cells, which become tumorigenic in immunodeficient NOD-SCID mice. Conversely, reconstitution of miR-15a and miR-16-1 expression results in growth arrest, apoptosis and marked regression of prostate tumor xenografts. Altogether, we propose that miR-15a and miR-16 act as tumor suppressor genes in prostate cancer through the control of cell survival, proliferation and invasion. These findings have therapeutic implications and may be exploited for future treatment of prostate cancer.

Background Circulating tumor cells (CTCs) are responsible for the metastatic dissemination of colorectal cancer (CRC) to the liver, lungs and lymph nodes. CTCs rarity and heterogeneity strongly limit the elucidation of their biological features, as well as preclinical drug sensitivity studies aimed at metastasis prevention. Methods We generated organoids from CTCs isolated from an orthotopic CRC xenograft model. CTCs-derived organoids (CTCDOs) were characterized through proteome profiling, immunohistochemistry, immunofluorescence, flow cytometry, tumor-forming capacity and drug screening assays. The expression of intra- and extracellular markers found in CTCDOs was validated on CTCs isolated from the peripheral blood of CRC patients. Results CTCDOs exhibited a hybrid epithelial-mesenchymal transition (EMT) state and an increased expression of stemness-associated markers including the two homeobox transcription factors Goosecoid and Pancreatic Duodenal Homeobox Gene-1 (PDX1), which were also detected in CTCs from CRC patients. Functionally, CTCDOs showed a higher migratory/invasive ability and a different response to pathway-targeted drugs as compared to xenograft-derived organoids (XDOs). Specifically, CTCDOs were more sensitive than XDOs to drugs affecting the Survivin pathway, which decreased the levels of Survivin and X-Linked Inhibitor of Apoptosis Protein (XIAP) inducing CTCDOs death. Conclusions These results indicate that CTCDOs recapitulate several features of colorectal CTCs and may be used to investigate the features of metastatic CRC cells, to identify new prognostic biomarkers and to devise new potential strategies for metastasis prevention.

Capsaicin, the main pungent component of chili peppers, exhibits several bioactive properties, such as modulation of adipogenesis and inhibition of liver steatosis by reducing cytoplasmic lipid accumulation. However, no evidence is currently available regarding its effect on the membrane fatty acid remodeling. In this work, we focused on the HepG2 cell model, commonly employed for hepatotoxicity, to examine the lipidome changes after treatment with capsaicin (10 µM), and its combination with oleic acid (100 µM), following the effects after 1.5, 3, and 24 h. In addition, cell viability, lipid accumulation, and secretion of inflammatory mediators were assessed. Notably, the combination of capsaicin with oleic acid completely reverted the correlation between cytokine/chemokine levels and omega-6/omega-3 fatty acids compared to capsaicin alone. Additionally, the combined treatment influenced the protective effect of capsaicin against polyunsaturated fatty acids, as investigated through biomimetic experiments.

Glioblastoma (GBM) is the most aggressive and prevalent form of a human brain tumor in adults. Several data have demonstrated the implication of microRNAs (miRNAs) in tumorigenicity of GBM stem-like cells (GSCs). The regulatory functions of miRNAs in GSCs have emerged as potential therapeutic candidates for glioma treatment. The current study aimed at investigating the function of miR-370-3p in glioma progression, as aberrant expression of miR-370-3p, is involved in various human cancers, including glioma. Analyzing our collection of GBM samples and patient-derived GSC lines, we found the expression of miR-370-3p significantly downregulated compared to normal brain tissues and normal neural stem cells. Restoration of miR-370-3p expression in GSCs significantly decreased proliferation, migration, and clonogenic abilities of GSCs, in vitro, and tumor growth in vivo. Gene expression analysis performed on miR-370-3p transduced GSCs, identified several transcripts involved in Epithelial to Mesenchymal Transition (EMT), and Hypoxia signaling pathways. Among the genes downregulated by the restored expression of miR-370-3p, we found the EMT-inducer high-mobility group AT-hook 2 (HMGA2), the master transcriptional regulator of the adaptive response to hypoxia, Hypoxia-inducible factor (HIF)1A, and the long non-coding RNAs (lncRNAs) Nuclear Enriched Abundant Transcript (NEAT)1. NEAT1 acts as an oncogene in a series of human cancers including gliomas, where it is regulated by the Epidermal Growth Factor Receptor (EGFR) pathways, and contributes to tumor growth and invasion. Noteworthy, the expression levels of miR-370-3p and NEAT1 were inversely related in both GBM tumor specimens and GSCs, and a dual-luciferase reporter assay proved the direct binding between miR-370-3p and the lncRNAs NEAT1. Our results identify a critical role of miR-370-3p in the regulation of GBM development, indicating that miR-370-3p acts as a tumor-suppressor factor inhibiting glioma cell growth, migration and invasion by targeting the lncRNAs NEAT1, HMGA2, and HIF1A, thus, providing a potential candidate for GBM patient treatment.

The process of drug discovery and pre‐clinical testing is currently inefficient, expensive, and time‐consuming. Most importantly, the success rate is unsatisfactory, as only a small percentage of tested drugs are made available to oncological patients. This is largely due to the lack of reliable models that accurately predict drug efficacy and safety. Even animal models often fail to replicate human‐specific pathologies and human body's complexity. These factors, along with ethical concerns regarding animal use, urge the development of suitable human‐relevant, translational in vitro models. The tumor microenvironment is an interactive system of cancer and non‐cancer cells along with the extracellular matrix, playing a crucial role in cancer development and progression. 3D models and co‐culture techniques allow for patient‐derived tissue models incorporating a wide array TME components, providing a more comprehensive representation of colorectal‐cancer's complexity and personalized treatment response.

Cancer stem cells (CSCs) are tumor subpopulations driving disease development, progression, relapse and therapy resistance, and their targeting ensures tumor eradication. CSCs display heterogeneous replication stress (RS), but the functionality/relevance of the RS response (RSR) centered on the ATR-CHK1 axis is debated. Here, we show that the RSR is efficient in primary CSCs from colorectal cancer (CRC-SCs), and describe unique roles for PARP1 and MRE11/RAD51. First, we demonstrated that PARP1 is upregulated in CRC-SCs resistant to several replication poisons and RSR inhibitors (RSRi). In these cells, PARP1 modulates replication fork speed resulting in low constitutive RS. Second, we showed that MRE11 and RAD51 cooperate in the genoprotection and mitosis execution of PARP1-upregulated CRC-SCs. These roles represent therapeutic vulnerabilities for CSCs. Indeed, PARP1i sensitized CRC-SCs to ATRi/CHK1i, inducing replication catastrophe, and prevented the development of resistance to CHK1i. Also, MRE11i + RAD51i selectively killed PARP1-upregulated CRC-SCs via mitotic catastrophe. These results provide the rationale for biomarker-driven clinical trials in CRC using distinct RSRi combinations.

Background: Despite recent improvements in therapy, the five-year survival rate for patients with advanced melanoma is poor, mainly due to the development of drug resistance. The aim of the present study was to investigate the mechanisms underlying this phenomenon, applying proteomics and structural approaches to models of melanoma cells. Methods: Sublines from two human (A375 and SK-MEL-28) cells with acquired vemurafenib resistance were established, and their proteomic profiles when exposed to denaturation were identified through LC-MS/MS analysis. The pathways derived from bioinformatics analyses were validated by in silico and functional studies. Results: The proteomic profiles of resistant melanoma cells were compared to parental counterparts by taking into account protein folding/unfolding behaviors. Several proteins were found to be involved, with dihydrolipoamide dehydrogenase (DLD) being the only one similarly affected by denaturation in all resistant cell sublines compared to parental ones. DLD expression was observed to be increased in resistant cells by Western blot analysis. Protein modeling analyses of DLD’s catalytic site coupled to in vitro assays with CPI-613, a specific DLD inhibitor, highlighted the role of DLD enzymatic functions in the molecular mechanisms of BRAFi resistance. Conclusions: Our proteomic and structural investigations on resistant sublines indicate that DLD may represent a novel and potent target for overcoming vemurafenib resistance in melanoma cells.