ERCC1 abundance is an indicator of DNA repair-apoptosis decision upon DNA damage.

DNA repair is essential for successful propagation of genetic material and fidelity of transcription. Nucleotide excision repair (NER) is one of the earliest DNA repair mechanisms, functionally conserved from bacteria to human. The fact that number of NER genes vary significantly between prokaryotes and metazoans gives the insight that NER proteins have evolved to acquire additional functions to combat challenges associated with a diploid genome, including being involved in the decision between DNA repair and apoptosis. However, no direct association between apoptosis and NER proteins has been shown to date. In this study, we induced apoptosis with a variety of agents, including oxaliplatin, doxorubicin and TRAIL, and observed changes in the abundance and molecular weight of NER complex proteins. Our results showed that XPA, XPC and ERCC1 protein levels change during DNA damage-induced apoptosis. Among these, ERCC1 decrease was observed as a pre-mitochondria depolarisation event which marks the "point of no return" in apoptosis signalling. ERCC1 decrease was due to proteasomal degradation upon lethal doses of oxaliplatin exposure. When ERCC1 protein was stabilised using proteasome inhibitors, the pro-apoptotic activity of oxaliplatin was attenuated. These results explain why clinical trials using proteasome inhibitors and platinum derivatives showed limited efficacy in carcinoma treatment and also the importance of how deep understanding of DNA repair mechanisms can improve cancer therapy.

Cancer cell-derived extracellular vesicles activate hepatic stellate cells in colorectal cancer.

Colorectal cancer (CRC) is the 2nd leading cause of cancer-related deaths worldwide, primarily due to the development of metastatic disease. The liver is the most frequently affected site. The metastatic cascade relies on a complex interaction between the immune system, tumor, and distant organs. Communication between the tumor and the metastatic site can be mediated by tumor-derived extracellular vesicles (EVs) and their cargo. The mechanisms underlying this process are starting to be understood through research that has rapidly expanded over the past 15 years. One crucial aspect is the remodeling of the microenvironment at the site of metastasis, which is essential for the formation of a premetastatic niche and the subsequent establishment of metastatic deposits. In the evaluated study, the authors use cellular experiments and a mouse model to investigate how tumour derived extracellular vesicles and their microRNA contents interact with hepatic stellate cells (HSCs). They demonstrate how this may lead to remodelling of the microenvironment and the formation of colorectal liver metastasis using their experimental model. In this mini review, we examine the current evidence surrounding tumour derived EVs and their effect on the tumour microenvironment to highlight potential areas for future research in CRC and other malignancies.

Risk-reducing surgery for individuals with cancer-predisposing germline pathogenic variants and no personal cancer history: a review of current UK guidelines.

Identifying healthy carriers of germline pathogenic variants in high penetrance cancer susceptibility genes offers the potential for risk-reducing surgery. The NHS England National Genomic Test Directory offers germline and somatic testing to patients with certain cancers or rare and inherited diseases, or, in some cases, to their relatives. This review summarises current UK guidelines for risk-reducing surgical interventions available for individuals with no personal history of cancer, who are determined to carry germline pathogenic variants. An electronic literature search of NICE guidelines and PubMed citable articles was performed. NICE guidelines are available for bilateral mastectomy and are currently in development for risk-reducing bilateral salpingo-oophorectomy. Guidelines developed with affiliation to, or through relevant British Surgical Societies or international consensus, are available for risk-reducing hysterectomy, polypectomy, gastrectomy, and thyroidectomy. There is a disparity in the development and distribution of national guidelines for interventions amongst tumour types. Whilst we are focusing on UK guidelines, we anticipate they will be relevant much more generally and so of interest to a wider audience including where there are no national guidelines to refer to. We suggest that, as genetic testing becomes rapidly more accessible, guideline development for interventions should be more closely aligned to those for testing.

Epithelial to mesenchymal transition influences fibroblast phenotype in colorectal cancer by altering miR-200 levels in extracellular vesicles.

Colorectal cancer (CRC) with a mesenchymal gene expression signature has the greatest propensity for distant metastasis and is characterised by the accumulation of cancer-associated fibroblasts in the stroma. We investigated whether the epithelial to mesenchymal transition status of CRC cells influences fibroblast phenotype, with a focus on the transfer of extracellular vesicles (EVs), as a controlled means of cell-cell communication. Epithelial CRC EVs suppressed TGF-ß-driven myofibroblast differentiation, whereas mesenchymal CRC EVs did not. This was driven by miR-200 (miR-200a/b/c, -141), which was enriched in epithelial CRC EVs and transferred to recipient fibroblasts. Ectopic miR-200 expression or ZEB1 knockdown, in fibroblasts, similarly suppressed myofibroblast differentiation. Supporting these findings, there was a strong negative correlation between miR-200 and myofibroblastic markers in a cohort of CRC patients in the TCGA dataset. This was replicated in mice, by co-injecting epithelial or mesenchymal CRC cells with fibroblasts and analysing stromal markers of myofibroblastic phenotype. Fibroblasts from epithelial tumours contained more miR-200 and expressed less ACTA2 and FN1 than those from mesenchymal tumours. As such, these data provide a new mechanism for the development of fibroblast heterogeneity in CRC, through EV-mediated transfer of miRNAs, and provide an explanation as to why CRC tumours with greater metastatic potential are CAF rich.

Sequential assessment of bowel function and anorectal physiology after anterior resection for cancer: a prospective cohort study.

AIM: The aim of this study was to investigate changes in bowel function and anorectal physiology (ARP) after anterior resection for colorectal cancer. METHOD: Patients were recruited from November 2006 to September 2008. Cleveland Clinic Incontinence (CCI) scores and stool frequency were determined by patient questionnaires before surgery (t0 ) and at three (t3 ), six (t6 ), nine (t9 ) and 12 (t12 ) months after restoration of intestinal continuity. ARP measurements were recorded at T0 , T3 and T12 . Endoanal ultrasound was performed at T0 and T12 . RESULTS: Eighty-nine patients were included. CCI score increased postoperatively then normalized, whereas stool frequency did not change. Patients who had neoadjuvant radiotherapy or a lower anastomosis had increased incontinence and stool frequency in the postoperative period, whereas those with defunctioning stomas or open surgery had increased stool frequency alone. Maximum resting pressure, volume at first urge and maximum rectal tolerance were reduced throughout the postoperative period. Radiotherapy, lower anastomosis and defunctioning stoma (but not operative approach) altered manometric parameters postoperatively. Maximum rectal tolerance correlated with incontinence and first urge with stool frequency. The length of the anterior internal anal sphincter decreased postoperatively. CONCLUSIONS: Incontinence recovers in the first year after anterior resection. Radiotherapy, lower anastomosis, defunctioning stoma and open surgery have a negative influence on bowel function. ARP may be useful if bowel dysfunction persists beyond 12 months.

The ZEB2-dependent EMT transcriptional programme drives therapy resistance by activating nucleotide excision repair genes ERCC1 and ERCC4 in colorectal cancer.

Resistance to adjuvant chemotherapy is a major clinical problem in the treatment of colorectal cancer (CRC). The aim of this study was to elucidate the role of an epithelial to mesenchymal transition (EMT)-inducing protein, ZEB2, in chemoresistance of CRC, and to uncover the underlying mechanism. We performed IHC for ZEB2 and association analyses with clinical outcomes on primary CRC and matched CRC liver metastases in compliance with observational biomarker study guidelines. ZEB2 expression in primary tumours was an independent prognostic marker of reduced overall survival and disease-free survival in patients who received adjuvant FOLFOX chemotherapy. ZEB2 expression was retained in 96% of liver metastases. The ZEB2-dependent EMT transcriptional programme activated nucleotide excision repair (NER) pathway largely via upregulation of the ERCC1 gene and other components in NER pathway, leading to enhanced viability of CRC cells upon oxaliplatin treatment. ERCC1-overexpressing CRC cells did not respond to oxaliplatin in vivo, as assessed using a murine orthotopic model in a randomised and blinded preclinical study. Our findings show that ZEB2 is a biomarker of tumour response to chemotherapy and risk of recurrence in CRC patients. We propose that the ZEB2-ERCC1 axis is a key determinant of chemoresistance in CRC.

Metabolic syndrome is a predictor of all site and liver-specific recurrence following primary resection of colorectal cancer: Prospective cohort study of 1006 patients.

INTRODUCTION: Large epidemiological studies have demonstrated the link between metabolic syndrome and cancer development, including colorectal cancer. However, the influence of metabolic syndrome on disease progression is less well studied, particularly in the post-surgical setting. This study investigates the effect of metabolic syndrome on colorectal cancer recurrence (all-site and liver-specific) after curative surgery for Stage I-III disease. MATERIALS AND METHODS: Consecutive patients who underwent curative resection for Stage I-III colorectal cancer in a single UK centre were prospectively recruited. Disease-free and overall survival with metabolic syndrome as a factor, were determined using the Kaplan-Meier technique. Hazard ratios for all-site and liver-specific recurrence were determined using univariable and multivariable Cox-regression models. RESULTS: 1006 patients were recruited and followed up for a median of 50 months (IQR 30-67). 177 patients (17.6%) met the criteria for metabolic syndrome. 245 patients (25.4%) developed recurrence, 161 (16.0%) of these had liver recurrence. The presence of metabolic syndrome was associated with a reduction in disease-free survival from 69 to 58 months (p < 0.001) and overall survival from 74 to 61 months (p < 0.001). Metabolic syndrome was an independent predictor of all-site (HR 1.76; p < 0.001) and liver-specific (HR 1.74; p = 0.01) recurrence. CONCLUSION: Metabolic syndrome is a predictor of all-site and liver-specific recurrence after primary resection of stage I-III colorectal cancer.

Protein kinase C inhibitors override ZEB1-induced chemoresistance in HCC.

Epithelial-mesenchymal transition (EMT) is a process by which tumour cells lose epithelial characteristics, become mesenchymal and highly motile. EMT pathways also induce stem cell features and resistance to apoptosis. Identifying and targeting this pool of tumour cells is a major challenge. Protein kinase C (PKC) inhibition has been shown to eliminate breast cancer stem cells but has never been assessed in hepatocellular cancer (HCC). We investigated ZEB family of EMT inducer expression as a biomarker for metastatic HCC and evaluated the efficacy of PKC inhibitors for HCC treatment. We showed that ZEB1 positivity predicted patient survival in multiple cohorts and also validated as an independent biomarker of HCC metastasis. ZEB1-expressing HCC cell lines became resistant to conventional chemotherapeutic agents and were enriched in CD44high/CD24low cell population. ZEB1- or TGFß-induced EMT increased PKCα abundance. Probing public databases ascertained a positive association of ZEB1 and PKCα expression in human HCC tumours. Inhibition of PKCα activity by small molecule inhibitors or by PKCA knockdown reduced viability of mesenchymal HCC cells in vitro and in vivo. Our results suggest that ZEB1 expression predicts survival and metastatic potential of HCC. Chemoresistant/mesenchymal HCC cells become addicted to PKC pathway and display sensitivity to PKC inhibitors such as UCN-01. Stratifying patients according to ZEB1 and combining UCN-01 with conventional chemotherapy may be an advantageous chemotherapeutic strategy.

Population-based observational study of acute pancreatitis in southern England.

INTRODUCTION: Acute pancreatitis is a common surgical emergency. Identifying variations in presentation, incidence and management may assist standardisation and optimisation of care. The objective of the study was to document the current incidence management and outcomes of acute pancreatitis against international guidelines, and to assess temporal trends over the past 20 years. METHODS: A prospective four-month audit of patients with acute pancreatitis was performed across the Wessex region. The Atlanta 2012 classifications were used to define cases, severity and complications. Outcomes were recorded using validated systems and correlated against guideline standards. Case ascertainment was validated with clinical coding and hospital episode statistics data. RESULTS: A total of 283 patient admissions with acute pancreatitis were identified. Aetiology included 153 gallstones (54%), 65 idiopathic (23%), 29 alcohol (10%), 9 endoscopic retrograde cholangiopancreatography (3%), 6 drug related (2%), 5 tumour (2%) and 16 other (6%). Compliance with guidelines had improved compared with our previous regional audit. Results were 6.5% mortality, 74% severity stratification, 23% idiopathic cases, 65% definitive treatment of gallstones within 2 weeks, 39% computed tomography within 6-10 days of severe pancreatitis presentation and 82% severe pancreatitis critical care admission. The Atlanta 2012 severity criteria significantly correlated with critical care stay, length of stay, development of complications and mortality (2% vs 6% vs 36%, P < 0.0001). CONCLUSIONS: The incidence of acute pancreatitis in southern England has risen substantially. The Atlanta 2012 classification identifies patients with severe pancreatitis who have a high risk of fatal outcome. Acute pancreatitis management is seen to have evolved in keeping with new evidence and updated clinical guidelines.

Sleeping beauty genetic screen identifies miR-23b::BTBD7 gene interaction as crucial for colorectal cancer metastasis.

BACKGROUND: Metastatic colorectal cancer (CRC) remains a deadly disease. Identifying locally advanced CRC patients with high risk of developing metastasis and improving outcome of metastatic CRC patients require discovering master regulators of metastasis. In this context, the non-coding part of the human genome is still largely unexplored. METHODS: To interrogate the non-coding part of the human genome and disclose regulators of CRC metastasis, we combined a transposon-based forward genetic screen with a novel in vitro assay, which forces cells to grow deprived of cell-substrate and cell-cell contacts (i.e. forced single cell suspension assay - fSCS). FINDINGS: We proved that fSCS selects CRC cells with mesenchymal and pro-metastatic traits. Moreover, we found that the transposon insertions conferred CRC cells resistance to fSCS and thus metastatic advantage. Among the retrieved transposon insertions, we demonstrated that the one located in the 3'UTR of BTBD7 disrupts miR-23b::BTBD7 interaction and contributes to pro-metastatic traits. In addition, miR-23b and BTBD7 correlate with CRC metastasis both in preclinical experiments and in clinical samples. INTERPRETATION: fSCS is a simple and scalable in vitro assay to investigate pro-metastatic traits and transposon-based genetic screens can interrogate the non-coding part of the human genome (e.g. miRNA::target interactions). Finally, both Btbd7 and miR-23b represent promising prognostic biomarkers and therapeutic targets in CRC. FUND: This work was supported by Marie Curie Actions (CIG n. 303877) and Friuli Venezia Giulia region (Grant Agreement n°245574), Italian Association for Cancer Research (AIRC, MFAG n°13589), Italian Ministry of Health (GR-2010-2319387 and PE-2016-02361040) and 5x1000 to CRO Aviano.

Transglutaminase-2 Mediates the Biomechanical Properties of the Colorectal Cancer Tissue Microenvironment that Contribute to Disease Progression.

Colorectal cancer is the third most common cancer worldwide, and the fourth leading cause of malignancy-related mortality. This highlights the need to understand the processes driving this disease in order to develop new treatments and improve patient outcomes. A potential therapeutic target is the increased stiffness of the tumour microenvironment, which is linked to aggressive cancer cell behaviour by enhancing biomechanical signalling. In this study, we used an siRNA-based approach to investigate the contribution of the protein cross-linking enzyme transglutaminase-2 (TG2) to matrix remodelling and biomechanical properties of the tumour microenvironment. TG2 inhibited cancer cell growth in organotypic 3D fibroblast/SW480 co-culture models, and biomechanical analysis demonstrated that colorectal cancer cells induced fibroblast-mediated stiffness which was inhibited by silencing TG2. These biomechanical changes were associated with observed alterations to collagen fibre structure, notably fibre thickness. Our in vitro findings of collagen composition changes were also seen with imaging biopsied tissues from patients with colorectal cancer, with TG2 correlating positively with thicker collagen fibres, and associating with poor outcome as determined by disease recurrence post-surgery and overall survival. In conclusion, this study demonstrates a role for TG2 in the stromal response to invading tumour, leading to tissue stiffening and poor outcome in patients.

Stem cell-like breast cancer cells with acquired resistance to metformin are sensitive to inhibitors of NADH-dependent CtBP dimerization.

Altered flux through major metabolic pathways is a hallmark of cancer cells and provides opportunities for therapy. Stem cell-like cancer (SCLC) cells can cause metastasis and therapy resistance. They possess metabolic plasticity, theoretically enabling resistance to therapies targeting a specific metabolic state. The C-terminal binding protein (CtBP) transcriptional regulators are potential therapeutic targets in highly glycolytic cancer cells, as they are activated by the glycolytic coenzyme nicotinamide adenine dinucleotide (NADH). However, SCLC cells commonly exist in an oxidative state with low rates of glycolysis. Metformin inhibits complex I of the mitochondrial electron transport chain; it can kill oxidative SCLC cells and has anti-cancer activity in patients. SCLC cells can acquire resistance to metformin through increased glycolysis. Given the potential for long-term metformin therapy, we have studied acquired metformin resistance in cells from the claudin-low subtype of breast cancer. Cells cultured for 8 weeks in sub-IC50 metformin concentration proliferated comparably to untreated cells and exhibited higher rates of glucose uptake. SCLC cells were enriched in metformin-adapted cultures. These SCLC cells acquired sensitivity to multiple methods of inhibition of CtBP function, including a cyclic peptide inhibitor of NADH-induced CtBP dimerization. Single-cell mRNA sequencing identified a reprogramming of epithelial-mesenchymal and stem cell gene expression in the metformin-adapted SCLC cells. These SCLC cells demonstrated an acquired dependency on one of these genes, Tenascin C. Thus, in addition to acquisition of sensitivity to glycolysis-targeting therapeutic strategies, the reprograming of gene expression in the metformin-adapted SCLC cells renders them sensitive to potential therapeutic approaches not directly linked to cell metabolism.

Analysis of Mutation and Loss of Heterozygosity by Whole-Exome Sequencing Yields Insights into Pseudomyxoma Peritonei.

Pseudomyxoma peritonei (PMP) is a clinical syndrome characterized by gross mucinous ascites originating from a disseminated intraperitoneal neoplasm. Although typically confined to the abdomen, mortality is high if untreated. Biomarkers, including genetic mutation profiles, may aid treatment selection and decision making. We applied whole-exome sequencing to five patients diagnosed with low-grade appendiceal mucinous neoplasms, using paired tumor and germline samples identify biomarkers. Multiple bioinformatic approaches were applied to these data to assess both somatic mutation profiles and loss of heterozygosity events. Mutation profiles of the tumors were consistent with deamination of methylcytosine being the prevailing mechanism. Pathogenic mutations were identified in both KRAS and GNAS in all samples, and further mutations in genes implicated in PMP, namely FGFR2, APC, SMAD2, and FAT4. No TP53 somatic mutations were identified, matching expectations for low-grade tumors. Four of five samples exhibited clonal loss of heterozygosity; these regions were further examined and found to contain genes harboring pathogenic somatic mutations in some samples. RNF43 was hereby implicated in the pathogenesis of PMP of appendiceal origin, having previously been found to increase sensitivity to Wnt signaling and to have involvement in similar mucinous tumors. In conclusion, we have investigated the mutation profile of PMP of appendiceal origin and provided the first report of RNF43 involvement in its progression.

The Colorectal Cancer Microenvironment: Strategies for Studying the Role of Cancer-Associated Fibroblasts.

Colorectal cancer (CRC) is a key public health concern and the second highest cause of cancer related death in Western society. A dynamic interaction exists between CRC cells and the surrounding tumor microenvironment, which can stimulate not only the development of CRC, but its progression and metastasis, as well as the development of resistance to therapy. In this chapter, we focus on the role of fibroblasts within the CRC tumor microenvironment and describe some of the key methods for their study, as well as the evaluation of dynamic interactions within this biological ecosystem.

Exosomal microRNAs (exomiRs): Small molecules with a big role in cancer.

Exosomes are secreted vesicles which can transmit molecular cargo between cells. Exosomal microRNAs (exomiRs) have drawn much attention in recent years because there is increasing evidence to suggest that loading of microRNAs into exosomes is not a random process. Preclinical studies have identified functional roles for exomiRs in influencing many hallmarks of cancer. Mechanisms underpinning their actions, such as exomiR receptors ("miRceptors"), are now becoming apparent. Even more exciting is the fact that exomiRs are highly suitable candidates for use as non-invasive biomarkers in an era of personalized cancer medicine.

Assessment of Nuclear ZEB2 as a Biomarker for Colorectal Cancer Outcome and TNM Risk Stratification.

Importance: At present, patients with colorectal cancer (CRC) are risk stratified using TNM histologic features. More recently, an association between a mesenchymal phenotype and a high risk of disease recurrence and micrometastases has been recognized. Objective: To investigate the association of the epithelial to mesenchymal transition (EMT)-inducing transcription factor ZEB2 (zinc finger E box-binding homeobox 2), survival outcomes, and the efficacy of ZEB2 as a biomarker when added as refinement to TNM staging after curative intent surgery for CRC. Design, Setting, and Participants: ZEB2 expression was assessed using a previously validated scoring system as part of a prospective, observational, masked diagnostic study from January 1, 2008, to December 31, 2013. Data were prospectively collected and analyzed for association with oncologic outcomes from January 1, 2017, to December 31, 2018. An initial test cohort from an academic university medical center of 126 consecutive patients with CRC and, subsequently, an independent validation cohort of 210 patients were examined. ZEB2 positivity was scored by 2 independent, masked pathologists. External validity was tested using an open access gene expression portal. Nomograms were developed with or without ZEB2. Main Outcomes and Measures: Systemic and local recurrence of CRC. Results: The test cohort consisted of 126 consecutive patients (mean [SD] age, 72.7 [11.7] years; 61 [48.4%] male) and the validation cohort of 210 patients (mean [SD] age, 72.0 [10.6] years; 111 [52.9%] male). A total of 52 tumors (41.3%) in the test cohort and 104 (49.5%) in the validation cohort were scored nuclear ZEB2 positive. Survival analysis by the log-rank test found that ZEB2 expression was associated with a significant reduction in overall survival and disease-free survival in both cohorts. Cox proportional hazards regression analysis highlighted ZEB2 as an independent biomarker of shorter overall survival and disease-free survival. Analysis of node-negative disease (n = 222) identified ZEB2 as an independent biomarker of early recurrence and reduced survival. External validation confirmed these findings. Addition of ZEB2 expression to nomograms composed of conventional TNM risk factors improved the ability to identify patients at high risk of recurrence demonstrated by the improvement in concordance index in both test (0.73 to 0.77) and validation (0.82 to 0.87) cohorts. Conclusions and Relevance: The findings suggest that expression of ZEB2 is associated with poor oncologic outcome and distant recurrence. The study also found that the addition of ZEB2 to existing TNM classification improved the ability to stratify patients for risk of recurrence. The results of this study suggest that addition of ZEB2 expression status to the TNM staging system improves the ability to stratify patients at high risk of recurrence.

Targeting the Myofibroblastic Cancer-Associated Fibroblast Phenotype Through Inhibition of NOX4.

Background: Cancer-associated fibroblasts (CAFs) are tumor-promoting and correlate with poor survival in many cancers, which has led to their emergence as potential therapeutic targets. However, effective methods to manipulate these cells clinically have yet to be developed. Methods: CAF accumulation and prognostic significance in head and neck cancer (oral, n = 260; oropharyngeal, n = 271), and colorectal cancer (n = 56) was analyzed using immunohistochemistry. Mechanisms regulating fibroblast-to-myofibroblast transdifferentiation were investigated in vitro using RNA interference/pharmacological inhibitors followed by polymerase chain reaction (PCR), immunoblotting, immunofluorescence, and functional assays. RNA sequencing/bioinformatics and immunohistochemistry were used to analyze NAD(P)H Oxidase-4 (NOX4) expression in different human tumors. NOX4's role in CAF-mediated tumor progression was assessed in vitro, using CAFs from multiple tissues in Transwell and organotypic culture assays, and in vivo, using xenograft (n = 9-15 per group) and isograft (n = 6 per group) tumor models. All statistical tests were two-sided. Results: Patients with moderate/high levels of myofibroblastic-CAF had a statistically significant decrease in cancer-specific survival rates in each cancer type analyzed (hazard ratios [HRs] = 1.69-7.25, 95% confidence intervals [CIs] = 1.11 to 31.30, log-rank P ≤ .01). Fibroblast-to-myofibroblast transdifferentiation was dependent on a delayed phase of intracellular reactive oxygen species, generated by NOX4, across different anatomical sites and differentiation stimuli. A statistically significant upregulation of NOX4 expression was found in multiple human cancers (P < .001), strongly correlating with myofibroblastic-CAFs (r = 0.65-0.91, adjusted P < .001). Genetic/pharmacological inhibition of NOX4 was found to revert the myofibroblastic-CAF phenotype ex vivo (54.3% decrease in α-smooth muscle actin [α-SMA], 95% CI = 10.6% to 80.9%, P = .009), prevent myofibroblastic-CAF accumulation in vivo (53.2%-79.0% decrease in α-SMA across different models, P ≤ .02) and slow tumor growth (30.6%-64.0% decrease across different models, P ≤ .04). Conclusions: These data suggest that pharmacological inhibition of NOX4 may have broad applicability for stromal targeting across cancer types.

Exosomal microRNAs derived from colorectal cancer-associated fibroblasts: role in driving cancer progression.

Colorectal cancer is a global disease with increasing incidence. Mortality is largely attributed to metastatic spread and therefore, a mechanistic dissection of the signals which influence tumor progression is needed. Cancer stroma plays a critical role in tumor proliferation, invasion and chemoresistance. Here, we sought to identify and characterize exosomal microRNAs as mediators of stromal-tumor signaling. In vitro, we demonstrated that fibroblast exosomes are transferred to colorectal cancer cells, with a resultant increase in cellular microRNA levels, impacting proliferation and chemoresistance. To probe this further, exosomal microRNAs were profiled from paired patient-derived normal and cancer-associated fibroblasts, from an ongoing prospective biomarker study. An exosomal cancer-associated fibroblast signature consisting of microRNAs 329, 181a, 199b, 382, 215 and 21 was identified. Of these, miR-21 had highest abundance and was enriched in exosomes. Orthotopic xenografts established with miR-21-overexpressing fibroblasts and CRC cells led to increased liver metastases compared to those established with control fibroblasts. Our data provide a novel stromal exosome signature in colorectal cancer, which has potential for biomarker validation. Furthermore, we confirmed the importance of stromal miR-21 in colorectal cancer progression using an orthotopic model, and propose that exosomes are a vehicle for miR-21 transfer between stromal fibroblasts and cancer cells.

A rectal cancer feasibility study with an embedded phase III trial design assessing magnetic resonance tumour regression grade (mrTRG) as a novel biomarker to stratify management by good and poor response to chemoradiotherapy (TRIGGER): study protocol for a randomised controlled trial.

BACKGROUND: Pre-operative chemoradiotherapy (CRT) for MRI-defined, locally advanced rectal cancer is primarily intended to reduce local recurrence rates by downstaging tumours, enabling an improved likelihood of curative resection. However, in a subset of patients complete tumour regression occurs implying that no viable tumour is present within the surgical specimen. This raises the possibility that surgery may have been avoided. It is also recognised that response to CRT is a key determinant of prognosis. Recent radiological advances enable this response to be assessed pre-operatively using the MRI tumour regression grade (mrTRG). Potentially, this allows modification of the baseline MRI-derived treatment strategy. Hence, in a 'good' mrTRG responder, with little or no evidence of tumour, surgery may be deferred. Conversely, a 'poor response' identifies an adverse prognostic group which may benefit from additional pre-operative therapy. METHODS/DESIGN: TRIGGER is a multicentre, open, interventional, randomised control feasibility study with an embedded phase III design. Patients with MRI-defined, locally advanced rectal adenocarcinoma deemed to require CRT will be eligible for recruitment. During CRT, patients will be randomised (1:2) between conventional management, according to baseline MRI, versus mrTRG-directed management. The primary endpoint of the feasibility phase is to assess the rate of patient recruitment and randomisation. Secondary endpoints include the rate of unit recruitment, acute drug toxicity, reproducibility of mrTRG reporting, surgical morbidity, pathological circumferential resection margin involvement, pathology regression grade, residual tumour cell density and surgical/specimen quality rates. The phase III trial will focus on long-term safety, regrowth rates, oncological survival analysis, quality of life and health economics analysis. DISCUSSION: The TRIGGER trial aims to determine whether patients with locally advanced rectal cancer can be recruited and subsequently randomised into a control trial that offers MRI-directed patient management according to radiological response to CRT (mrTRG). The feasibility study will inform a phase III trial design investigating stratified treatment of good and poor responders according to 3-year disease-free survival, colostomy-free survival as well as an increase in cases managed without a major resection. TRIAL REGISTRATION: ClinicalTrials.gov, ID: NCT02704520 . Registered on 5 February 2016.