Chromatin factors: Ready to roll as biomarkers in metastatic colorectal cancer?

Colorectal cancer (CRC) ranks as the third most prevalent cancer globally and stands as the fourth leading cause of cancer-related fatalities in 2020. Survival rates for metastatic disease have slightly improved in recent decades, with clinical trials showing median overall survival of approximately 24-30 months. This progress can be attributed to the integration of chemotherapeutic treatments alongside targeted therapies and immunotherapy. Despite these modest improvements, the primary obstacle to successful treatment for advanced CRC lies in the development of chemoresistance, whether inherent or acquired, which remains the major cause of treatment failure. Epigenetics has emerged as a hallmark of cancer, contributing to master transcription regulation and genome stability maintenance. As a result, epigenetic factors are starting to appear as potential clinical biomarkers for diagnosis, prognosis, and prediction of treatment response in CRC.In recent years, numerous studies have investigated the influence of DNA methylation, histone modifications, and chromatin remodelers on responses to chemotherapeutic treatments. While there is accumulating evidence indicating their significant involvement in various types of cancers, the exact relationship between chromatin landscapes and treatment modulation in CRC remains elusive. This review aims to provide a comprehensive summary of the most pertinent and extensively researched epigenetic-associated mechanisms described between 2015 and 2022 and their potential usefulness as predictive biomarkers in the metastatic disease

PKM2 subcellular localization is involved in oxaliplatin resistance acquisition in HT29 human colorectal cancer cell lines

Ajuts: Beca bianual de la Fundació Olga Torres 2008-2009Chemoresistance is the main cause of treatment failure in advanced colorectal cancer (CRC). However, molecular mechanisms underlying this phenomenon remain to be elucidated. In a previous work we identified low levels of PKM2 as a putative oxaliplatin-resistance marker in HT29 CRC cell lines and also in patients. In order to assess how PKM2 influences oxaliplatin response in CRC cells, we silenced PKM2 using specific siRNAs in HT29, SW480 and HCT116 cells. MTT test demonstrated that PKM2 silencing induced resistance in HT29 and SW480 cells and sensitivity in HCT116 cells. Same experiments in isogenic HCT116 p53 null cells and double silencing of p53 and PKM2 in HT29 cells failed to show an influence of p53. By using trypan blue stain and FITC-Annexin V/PI tests we detected that PKM2 knockdown was associated with an increase in cell viability but not with a decrease in apoptosis activation in HT29 cells. Fluorescence microscopy revealed PKM2 nuclear translocation in response to oxaliplatin in HCT116 and HT29 cells but not in OXA-resistant HTOXAR3 cells. Finally, by using a qPCR Array we demonstrated that oxaliplatin and PKM2 silencing altered cell death gene expression patterns including those of BMF, which was significantly increased in HT29 cells in response to oxaliplatin, in a dose and time-dependent manner, but not in siPKM2-HT29 and HTOXAR3 cells. BMF gene silencing in HT29 cells lead to a decrease in oxaliplatin-induced cell death. In conclusion, our data report new non-glycolytic roles of PKM2 in response to genotoxic damage and proposes BMF as a possible target gene of PKM2 to be involved in oxaliplatin response and resistance in CRC cells

Resistant mechanisms to BRAF inhibitors in melanoma

Patients with advanced melanoma have traditionally had very poor prognosis. However, since 2011 better understanding of the biology and epidemiology of this disease has revolutionized its treatment, with newer therapies becoming available. These newer therapies can be classified into immunotherapy and targeted therapy. The immunotherapy arsenal includes inhibitors of CTLA4, PD-1 and PDL-1, while targeted therapy focuses on BRAF and MEK. BRAF inhibitors (vemurafenib, dabrafenib) have shown benefit in terms of overall survival (OS) compared to chemotherapy, and their combination with MEK inhibitors has recently been shown to improve progression-free survival (PFS), compared with monotherapy with BRAF inhibitors. However, almost 20% of patients initially do not respond, due to intrinsic resistance to therapy and, of those who do, most eventually develop mechanisms of acquired resistance, including reactivation of the MAP kinase pathway, persistent activation of receptor tyrosine kinase (RTKS) receptor, activation of phosphatidyinositol-3OH kinase, overexpression of epidermal growth factor receptor (EGFR), and interactions with the tumor microenvironment. Herein we comment in detail on mechanisms of resistance to targeted therapy and discuss the strategies to overcome them

Epigenetic homogeneity within colorectal tumors predicts shorter relapse-free and overall survival times for patients with locoregional cancer

Background & aims: there are few validated biomarkers that can be used to predict outcomes for patients with colorectal cancer. Part of the challenge is the genetic and molecular heterogeneity of colorectal tumors not only among patients, but also within tumors. We have explored intratumor heterogeneity at the epigenetic level, due to its dynamic nature. We analyzed DNA methylation profiles of the digestive tract surface and the central bulk and invasive front regions of colorectal tumors. Methods: we determined the DNA methylation profiles of >450,000 CpG sites in 3 macrodissected regions of 79 colorectal tumors and 23 associated liver metastases, obtained from 2 hospitals in Spain. We also analyzed samples for KRAS and BRAF mutations, 499,170 single nucleotide polymorphisms, and performed immunohistochemical analyses. Results: we observed differences in DNA methylation among the 3 tumor sections; regions of tumor−host interface differed the most from the other tumor sections. Interestingly, tumor samples collected from areas closer to the gastrointestinal transit most frequently shared methylation events with metastases. When we calculated individual coefficients to quantify heterogeneity, we found that epigenetic homogeneity was significantly associated with short time of relapse-free survival (log-rank P = .037) and short time of overall survival (log-rank P = .026) in patients with locoregional colorectal cancer. Conclusions: in an analysis of 79 colorectal tumors, we found significant heterogeneity in patterns of DNA methylation within each tumor; the level of heterogeneity correlates with times of relapse-free and overall survival

Curcumin mediates oxaliplatin-acquired resistance reversion in colorectal cancer cell lines through modulation of CXC-Chemokine/NF-κB signalling pathway

This study was funded by the ISCIII grant, project n° PI1202228 and Departament d'Innovació, Universitats i Empresa, Generalitat de Catalunya. SGR-PREDIVHICO. This work was done under the framework of the doctorate in Medicine from the Universitat Autònoma de Barcelona. We thank Dr. Lucía Sanjurjo (Innate Immunity Group, IGTP, Badalona, Spain) for her technical assistance and support and Dr. Verónica Guirao (Biobank research support unit, IGTP, Badalona, Spain) for her comments and editorial assistance.Resistance to oxaliplatin (OXA) is a complex process affecting the outcomes of metastatic colorectal cancer (CRC) patients treated with this drug. De-regulation of the NF-κB signalling pathway has been proposed as an important mechanism involved in this phenomenon. Here, we show that NF-κB was hyperactivated in in vitro models of OXA-acquired resistance but was attenuated by the addition of Curcumin, a non-toxic NF-κB inhibitor. The concomitant combination of Curcumin + OXA was more effective and synergistic in cell lines with acquired resistance to OXA, leading to the reversion of their resistant phenotype, through the inhibition of the NF-κB signalling cascade. Transcriptomic profiling revealed the up-regulation of three NF-κB-regulated CXC-chemokines, CXCL8, CXCL1 and CXCL2, in the resistant cells that were more efficiently down-regulated after OXA + Curcumin treatment as compared to the sensitive cells. Moreover, CXCL8 and CXCL1 gene silencing made resistant cells more sensitive to OXA through the inhibition of the Akt/NF-κB pathway. High expression of CXCL1 in FFPE samples from explant cultures of CRC patients-derived liver metastases was associated with response to OXA + Curcumin. In conclusion, we suggest that combination of OXA + Curcumin could be an effective treatment, for which CXCL1 could be used as a predictive marker, in CRC patients

Curcumin mediates oxaliplatin-acquired resistance reversion in colorectal cancer cell lines through modulation of CXC-Chemokine/NF-κB signalling pathway

Resistance to oxaliplatin (OXA) is a complex process affecting the outcomes of metastatic colorectal cancer (CRC) patients treated with this drug. De-regulation of the NF-kappa B signalling pathway has been proposed as an important mechanism involved in this phenomenon. Here, we show that NF-kappa B was hyperactivated in in vitro models of OXA-acquired resistance but was attenuated by the addition of Curcumin, a non-toxic NF-kappa B inhibitor. The concomitant combination of Curcumin + OXA was more effective and synergistic in cell lines with acquired resistance to OXA, leading to the reversion of their resistant phenotype, through the inhibition of the NF-kappa B signalling cascade. Transcriptomic profiling revealed the up-regulation of three NF-kappa B-regulated CXC-chemokines, CXCL8, CXCL1 and CXCL2, in the resistant cells that were more efficiently down-regulated after OXA + Curcumin treatment as compared to the sensitive cells. Moreover, CXCL8 and CXCL1 gene silencing made resistant cells more sensitive to OXA through the inhibition of the Akt/NF-kappa B pathway. High expression of CXCL1 in FFPE samples from explant cultures of CRC patients-derived liver metastases was associated with response to OXA + Curcumin. In conclusion, we suggest that combination of OXA + Curcumin could be an effective treatment, for which CXCL1 could be used as a predictive marker, in CRC patients

Carcinoma-associated fibroblasts affect sensitivity to oxaliplatin and 5FU in colorectal cancer cells

The importance of tumor microenvironment (TME) as a relevant contributor to cancer progression and its role in the development of de novo resistance to targeted therapies has become increasingly apparent. However, the mechanisms of microenvironment-mediated drug resistance for nonspecific conventional chemotherapeutic agents, such as platinum compounds or antimetabolites, are still unclear. Here we describe a mechanism induced by soluble factors released by carcinoma-associated fibroblasts (CAFs) that induce the translocation of AKT, Survivin and P38 to the nucleus of tumor cells. These changes are guided to ensure DNA repair and the correct entrance and exit from mitosis in the presence of chemotherapy. We used conditioned media (CM) from normal-colonic fibroblasts and paired CAFs to assess dose response curves of oxaliplatin and 5-fluorouracil, separately or combined, compared with standard culture medium. We also evaluated a colony-forming assay and cell death to demonstrate the protective role of CAF-CM. Immunofluorescence confirmed the translocation of AKT, P38 and Survivin to the nucleus induced by CAF-soluble factors. We also have shown that STAT3 or P38 inhibition provides a promising strategy for overcoming microenvironment-mediated resistance. Conversely, pharmacologic AKT inhibition induces an antagonistic effect that relieves a cMET and STAT3-mediated compensatory feedback that might explain the failure of AKT inhibitors in the clinic so far

Translational research opportunities regarding homologous recombination in ovarian cancer

Homologous recombination (HR) is a DNA repair pathway that is deficient in 50% of high-grade serous ovarian carcinomas (HGSOC). Deficient HR (DHR) constitutes a therapeutic opportunity for these patients, thanks to poly (ADP-ribose) polymerases (PARP) inhibitors (PARPi; olaparib, niraparib, and rucaparib are already commercialized). Although initially, PARPi were developed for patients with BRCA1/2 mutations, robust clinical data have shown their benefit in a broader population without DHR. This breakthrough in daily practice has raised several questions that necessitate further research: How can populations that will most benefit from PARPi be selected? At which stage of Ovarian Cancer should PARPi be used? Which strategies are reasonable to overcome PARPi resistance? In this paper, we present a summary of the literature and discuss the present clinical research involving PARPi (after reviewing ClinicalTrials.gov) from a translational perspective. Research into the functional biomarkers of DHR and clinical trials testing PARPi benefits as first-line setting or rechallenge are currently ongoing. Additionally, in the clinical setting, only secondary restoring mutations of BRCA1/2 have been identified as events inducing resistance to PARPi. The clinical frequency of this and other mechanisms that have been described in preclinics is unknown. It is of great importance to study mechanisms of resistance to PARPi to guide the clinical development of drug combinations

Tumor Expression of Cyclin-Dependent Kinase 5 (Cdk5) Is a Prognostic Biomarker and Predicts Outcome of Oxaliplatin-Treated Metastatic Colorectal Cancer Patients

In recent years, an increasing number of studies have shown that elevated expression of cyclin dependent kinase (Cdk5) contributes to the oncogenic initiation and progression of many types of cancers. In this study, we investigated the expression pattern of Cdk5 in colorectal cancer (CRC) cell lines and in a large number of tumor samples in order to evaluate its relevance in this pathogenesis and possible use as a prognostic marker. We found that Cdk5 is highly expressed and activated in CRC cell lines and that silencing of the kinase decreases their migration ability. In tumor tissues, Cdk5 is overexpressed compared to normal tissues due to a copy number gain. In patients with localized disease, we found that high Cdk5 levels correlate with poor prognosis, while in the metastatic setting, this was only the case for patients receiving an oxaliplatin-based treatment. When exploring the Cdk5 levels in the consensus molecular subtypes (CMS), we found the lowest levels in subtype 1, where high Cdk5 again was associated with a poorer prognosis. In conclusion, we confirm that Cdk5 is involved in CRC and disease progression and that it could serve as a prognostic and predictive biomarker in this disease

Tumor expression of cyclin-dependent kinase 5 (Cdk5) is a prognostic biomarker and predicts outcome of oxaliplatin-treated metastatic colorectal cancer patients

In recent years, an increasing number of studies have shown that elevated expression of cyclin dependent kinase (Cdk5) contributes to the oncogenic initiation and progression of many types of cancers. In this study, we investigated the expression pattern of Cdk5 in colorectal cancer (CRC) cell lines and in a large number of tumor samples in order to evaluate its relevance in this pathogenesis and possible use as a prognostic marker. We found that Cdk5 is highly expressed and activated in CRC cell lines and that silencing of the kinase decreases their migration ability. In tumor tissues, Cdk5 is overexpressed compared to normal tissues due to a copy number gain. In patients with localized disease, we found that high Cdk5 levels correlate with poor prognosis, while in the metastatic setting, this was only the case for patients receiving an oxaliplatin-based treatment. When exploring the Cdk5 levels in the consensus molecular subtypes (CMS), we found the lowest levels in subtype 1, where high Cdk5 again was associated with a poorer prognosis. In conclusion, we confirm that Cdk5 is involved in CRC and disease progression and that it could serve as a prognostic and predictive biomarker in this disease