Genetic and immune landscape evolution in MMR-deficient colorectal cancer.

Mismatch repair-deficient (MMRd) colorectal cancers (CRCs) have high mutation burdens, which make these tumours immunogenic and many respond to immune checkpoint inhibitors. The MMRd hypermutator phenotype may also promote intratumour heterogeneity (ITH) and cancer evolution. We applied multiregion sequencing and CD8 and programmed death ligand 1 (PD-L1) immunostaining to systematically investigate ITH and how genetic and immune landscapes coevolve. All cases had high truncal mutation burdens. Despite pervasive ITH, driver aberrations showed a clear hierarchy. Those in WNT/ß-catenin, mitogen-activated protein kinase, and TGF-ß receptor family genes were almost always truncal. Immune evasion (IE) drivers, such as inactivation of genes involved in antigen presentation or IFN-γ signalling, were predominantly subclonal and showed parallel evolution. These IE drivers have been implicated in immune checkpoint inhibitor resistance or sensitivity. Clonality assessments are therefore important for the development of predictive immunotherapy biomarkers in MMRd CRCs. Phylogenetic analysis identified three distinct patterns of IE driver evolution: pan-tumour evolution, subclonal evolution, and evolutionary stasis. These, but neither mutation burdens nor heterogeneity metrics, significantly correlated with T-cell densities, which were used as a surrogate marker of tumour immunogenicity. Furthermore, this revealed that genetic and T-cell infiltrates coevolve in MMRd CRCs. Low T-cell densities in the subgroup without any known IE drivers may indicate an, as yet unknown, IE mechanism. PD-L1 was expressed in the tumour microenvironment in most samples and correlated with T-cell densities. However, PD-L1 expression in cancer cells was independent of T-cell densities but strongly associated with loss of the intestinal homeobox transcription factor CDX2. This explains infrequent PD-L1 expression by cancer cells and may contribute to a higher recurrence risk of MMRd CRCs with impaired CDX2 expression. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Pre-therapeutic efficacy of the CDK inhibitor dinaciclib in medulloblastoma cells.

Medulloblastoma (MB) is the most common aggressive paediatric brain tumour and, despite the recent progress in the treatments of MB patients, there is still an urgent need of complementary or alternative therapeutic options for MB infants. Cyclin Dependent Kinase inhibitors (CDKi) are at the front-line of novel targeted treatments for multiple cancers and the CDK4/6 specific inhibitor palbociclib has been pre-clinically identified as an effective option for MB cells. Herein, we identified the pan-CDKi dinaciclib as a promising alternative to palbociclib for the suppression of MB cells proliferation. We present evidence supporting dinaciclib's ability to inhibit MB cells in vitro proliferation at considerably lower doses than palbociclib. Sequencing data and pathway analysis suggested that dinaciclib is a potent cell death inducer in MB cells. We found that dinaciclib-triggered apoptosis is triggered by CDK9 inhibition and the resultant reduction in RNA pol II phosphorylation, which leads to the downregulation of the oncogenic marker MYC, and the anti-apoptotic protein MCL-1. Specifically, we demonstrated that MCL-1 is a key apoptotic mediator for MB cells and co-treatment of dinaciclib with BH3 mimetics boosts the therapeutic efficacy of dinaciclib. Together, these findings highlight the potential of multi-CDK inhibition by dinaciclib as an alternative option to CDK4/6 specific inhibition, frequently associated with drug resistance in patients.

Differential Role of Circulating microRNAs to Track Progression and Pre-Symptomatic Stage of Chronic Heart Failure: A Pilot Study.

(1)Background: Chronic heart failure (CHF) contributes to the overall burden of cardiovascular disease. Early identification of at-risk individuals may facilitate the targeting of precision therapies. Plasma microRNAs are promising circulating biomarkers for their implications with cardiac pathologies. In this pilot study, we investigate the possible exploitability of circulating micro-RNAs (miRNAs) to track chronic heart failure (CHF) occurrence, and progression from NYHA class I to IV. (2)Methods: We screened 367 microRNAs using TaqMan microRNA Arrays in plasma samples from healthy controls (HC) and CHF NYHA-class I-to-IV patients (5/group). Validation was performed by singleplex assays on 10 HC and 61 CHF subjects. Differences in the expression of validated microRNAs were evaluated through analysis of covariance (ANCOVA). Associations between N-terminal pro-BNP (NT-proBNP), left ventricular end-diastolic volume (LVEDV) or peak oxygen uptake (VO2 peak) and plasma microRNA were assessed by multivariable linear regression analysis. (3)Results: Twelve microRNAs showed higher expression in CHF patients vs. HC. Seven microRNAs were associated with NT-proBNP concentration; of these, miR-423-5p was also an independent predictor of LVEDV. Moreover, miR-499-5p was a predictor of the VO2 peak. Finally, a cluster of 5 miRNAs discriminated New York Heart Association (NYHA) class-I from HC subjects. (4)Conclusions: Our data suggest that circulating miRNAs have the potential to serve as pathophysiology-based markers of HF status and progression, and as indicators of pre-symptomatic individuals.

Vulnerability of drug-resistant EML4-ALK rearranged lung cancer to transcriptional inhibition.

A subset of lung adenocarcinomas is driven by the EML4-ALK translocation. Even though ALK inhibitors in the clinic lead to excellent initial responses, acquired resistance to these inhibitors due to on-target mutations or parallel pathway alterations is a major clinical challenge. Exploring these mechanisms of resistance, we found that EML4-ALK cells parental or resistant to crizotinib, ceritinib or alectinib are remarkably sensitive to inhibition of CDK7/12 with THZ1 and CDK9 with alvocidib or dinaciclib. These compounds robustly induce apoptosis through transcriptional inhibition and downregulation of anti-apoptotic genes. Importantly, alvocidib reduced tumour progression in xenograft mouse models. In summary, our study takes advantage of the transcriptional addiction hypothesis to propose a new treatment strategy for a subset of patients with acquired resistance to first-, second- and third-generation ALK inhibitors.

Plasmatic and chamber-specific modulation of cardiac microRNAs in an acute model of DOX-induced cardiotoxicity.

BACKGROUND: Doxorubicin (DOX) is a chemotherapeutic drug limited in its usefulness by an adverse side effect, cardiotoxicity. The mechanisms leading to this detrimental occurrence are not completely clear, and lately many authors focused their attention on the possible role of microRNAs (miRNAs), small regulators of cardiovascular functions, in this phenomenon. Notably, these molecules recently emerged also as potential circulating biomarkers of several cardiac diseases. Thus, the aim of this study was the simultaneous investigation of circulating and cardiac tissue miRNAs expression upon DOX treatment in vivo. METHODS: Twenty C57BL/6 female mice were administered with 24 mg/Kg cumulative dose of DOX or saline (CTRL) for 2 weeks. Echocardiography was performed at baseline and at the end of treatment (T1). Plasma and heart samples were collected at T1, separating atria from left (LV) and right (RV) ventricles, and miRNAs expression was tested by RT-qPCR-based arrays. All putatively DOX-regulated candidates were then validated by single assays in vivo and then evaluated also in murine immortalized cardiomyocytes (HL-1) treated with 1 µM DOX for 24 h. In the end, bioinformatics target prediction was performed for all DOX-miRNAs. RESULTS: Cardiotoxicity onset was diagnosed upon impairment of six cardiac functional parameters in DOX-treated mice at T1. Samples collection, followed by screening and validation steps, identified eleven miRNAs dysregulated by the drug in plasma, while seven resulted as altered in separate heart chambers. Interestingly, miR-34a-5p and miR-451a showed a dysregulation in both plasma and tissue samples of DOX-administered animals, whereas five additional miRNAs presented chamber specific modulation. Of note, in vitro experiments showed a very modest overlap with in vivo results. Bioinformatics prediction analysis performed on miR-34a-5p and miR-451a identified several putative targets presenting no significant association with cardiotoxicity. Anyhow, the same analyses, conducted by combining all miRNAs regulated by DOX in each heart chamber, evidenced a possible dysregulation of the adherens junctions gene network, known to be involved in the onset and progression of dilated cardiomyopathy, an established detrimental side effect of the drug. CONCLUSIONS: This is the first work investigating miRNAs regulation by DOX both in plasma and heart districts of treated animals. Our results indicate a strong association of miR-34a-5p and miR-451a to DOX-induced cardiotoxicity. In addition, the observed altered expression of diverse miRNAs in separated cardiac chambers hints at a specific response to the drug, implying the existence of different players and pathways leading to dysfunction onset.

A Specific Circulating MicroRNA Cluster Is Associated to Late Differential Cardiac Response to Doxorubicin-Induced Cardiotoxicity In Vivo.

BACKGROUND: Cardiotoxicity is a detrimental side effect of the anticancer drug doxorubicin (DOX), characterized by progressive heart dysfunction. Circulating microRNAs (miRNAs) are recognized as potential biomarkers of cardiac disease; thus, we aimed to investigate their association with late cardiotoxicity in an animal model of disease. METHODS: Twenty C57BL/6 female mice were administered with 24 mg/kg cumulative dose of DOX or saline during 2 weeks, followed by a recovery period of one month (T42). Echocardiography was performed at baseline and at T42, and plasma samples were collected at T42. The selection of all miRNAs of interest was conducted by literature overview and by screening, followed by RT-qPCR validation. Results. The analysis of cardiac function at T42 evidenced five DOX-treated animals indistinguishable (NoTox) from controls (CTRLs), while four presented heart impairment (Tox). Our analyses identified eight dysfunction-associated plasma miRNAs. In particular, seven miRNAs were found downregulated in comparison to CTRLs, miR-1-3p, miR-122-5p, miR-127-3p, miR-133a-3p, miR-215-5p, miR-455-3-p, and miR-499a-5p. Conversely, miR-34a-5p showed increased levels in Tox plasma samples. Noteworthy, we determined a cluster composed of miR-1-3p, miR-34a-5p, miR-133a-3p, and miR-499a-5p that distinguished with high-accuracy Tox from NoTox mice. CONCLUSION: This is the first study indicating that, similarly to what is observed in patients, DOX-administered animals present a differential cardiac response to treatment. Moreover, our results indicate the presence of specific plasma miRNAs whose expression reflect the presence of cardiac dysfunction in response to drug-induced injury.

miRNAs in bone metastasis.

INTRODUCTION: Bone metastasis is one of the most common forms of metastasis from a number of different primary carcinomas. MicroRNAs (miRNAs) are short, endogenous RNAs that negatively regulate gene expression to control essential pathways, including those involved in bone organogenesis and homeostasis. As these pathways are often hijacked during bone metastasis, it is not surprising that miRNAs can also influence bone metastasis formation. Areas covered: In this review, we first summarize the major signalling pathways involved in normal bone development and bone metastasis. We will then discuss the overall roles of miRNAs in cancer metastasis and highlight the recent findings on the effects of miRNAs in bone metastasis. To this aim, we have performed a literature search in PubMed by using the search words 'miRNAs' and 'bone metastasis', selecting relevant scientific articles published between 2010 and 2016. Seminal publications before 2010 on the metastatic role of miRNAs have also been considered. Expert commentary: With the lack of current diagnostic biomarkers and effective targeted therapies for bone metastasis, the significant role of miRNAs in the regulation of bone homeostasis and bone metastasis may support the future use of miRNAs as diagnostic biomarkers and therapeutic targets.