Colorectal cancer (CRC) is a heterogeneous disease that can currently be subdivided into four distinct consensus molecular subtypes (CMS) based on gene expression profiling. The CMS4 subtype is marked by high expression of mesenchymal genes and is associated with a worse overall prognosis compared to other CMSs. Importantly, this subtype responds poorly to the standard therapies currently used to treat CRC. We set out to explore what regulatory signalling networks underlie the CMS4 phenotype of cancer cells, specifically, by analysing which kinases were more highly expressed in this subtype compared to others. We found AKT3 to be expressed in the cancer cell epithelium of CRC specimens, patient derived xenograft (PDX) models and in (primary) cell cultures representing CMS4. Importantly, chemical inhibition or knockout of this gene hampers outgrowth of this subtype, as AKT3 controls expression of the cell cycle regulator p27^KIP1. Furthermore, high AKT3 expression was associated with high expression of epithelial-mesenchymal transition (EMT) genes, and this observation could be expanded to cell lines representing other carcinoma types. More importantly, this association allowed for the identification of CRC patients with a high propensity to metastasise and an associated poor prognosis. High AKT3 expression in the tumour epithelial compartment may thus be used as a surrogate marker for EMT and may allow for a selection of CRC patients that could benefit from AKT3-targeted therapy.

Previously, colorectal cancer (CRC) has been classified into four distinct molecular subtypes based on transcriptome data. These consensus molecular subtypes (CMSs) have implications for our understanding of tumor heterogeneity and the prognosis of patients. So far, this classification has been based on the use of messenger RNAs (mRNAs), although microRNAs (miRNAs) have also been shown to play a role in tumor heterogeneity and biological differences between CMSs. In contrast to mRNAs, miRNAs have a smaller size and increased stability, facilitating their detection. Therefore, we built a miRNA‐based CMS classifier by converting the existing mRNA‐based CMS classification using machine learning (training dataset of n = 271). The performance of this miRNA‐assigned CMS classifier (CMS‐miRaCl) was evaluated in several datasets, achieving an overall accuracy of ~ 0.72 (0.6329–0.7987) in the largest dataset (n = 158). To gain insight into the biological relevance of CMS‐miRaCl, we evaluated the most important features in the classifier. We found that miRNAs previously reported to be relevant in microsatellite‐instable CRCs or Wnt signaling were important features for CMS‐miRaCl. Following further studies to validate its robustness, this miRNA‐based alternative might simplify the implementation of CMS classification in clinical workflows.

Colorectal cancer (CRC) is stratified into four consensus molecular subtypes (CMS1-4). CMS3 represents the metabolic subtype, but its wiring remains largely undefined. To identify the underlying tumorigenesis of CMS3, organoids derived from 16 genetically engineered mouse models are analyzed. Upon in vitro Cre-recombinase activation, transformation is established and transcriptional profiling reveals that distinct CMSs (CMS2-4) are modeled with different organoids. CMS3-like, metabolic signature-positive, organoids are induced by KRAS mutations. Interestingly, metabolic signatures are subsequently shown to result from enterocyte-like differentiation both in organoids and human cancers. Further analysis reveals carbamoyl-phosphate synthase 1 (CPS1) and sucrase-isomaltase (SI) as signature proteins. More importantly, CPS1 is crucial for de novo pyrimidine synthesis in CMS3 and its inhibition targets proliferation and stemness, facilitating enterocyte-like differentiation, while CMS2 and CMS4 models are not affected. Our data point to an enterocyte-like differentiation of CMS3 CRCs and reveal a selective vulnerability of this subtype through CPS1 inhibition.

Colorectal cancer (CRC) can be divided into 4 subtypes of which consensus molecular subtype 4 (CMS4) is associated with metastasis and poor survival. Previously, we reported that the KPN mouse model resembles human CMS4. Strikingly, although tumor formation in this model is slow and limited, effective metastasis is observed. To understand this aggressive behavior, we compared two distinct in vitro KPN models, organoids and tumoroids. The organoid model only carries the original mutations, while the tumoroids are derived from in vivo grown tumors that underwent selection during development. Here, we reveal that tumoroids harbor endogenous WNT pathway activity, which can be driven by tankyrase activity and Cdx2 downregulation. Importantly, WNT pathway activation was heterogeneous in nature, subject to regulation and allowed for a mixture of WNT-driven and YAP-driven cells within tumoroids. This unique type of WNT pathway activation is not crucial for colonic tumor growth, but results in metastatic spreading. Intriguingly, these findings reflect a specific subset of aggressive human CMS4 cancers that display low CDX2 expression and lack of classical WNT pathway mutations, while having a higher tendency to metastasize. Together, these data propose a novel mechanism for WNT pathway activation that drives metastasis formation in aggressive CRC.

The consensus molecular subtype (CMS) classification divides colon tumors into four subtypes holding promise as a predictive biomarker. However, the effect of adjuvant chemotherapy on recurrence free survival (RFS) per CMS in stage III patients remains inadequately explored. With this intention, we selected stage III colon cancer (CC) patients from the MATCH cohort (n = 575) and RadboudUMC (n = 276) diagnosed between 2005 and 2018. Patients treated with and without adjuvant chemotherapy were matched based on tumor location, T‐ and N‐stage (n = 522). Tumor material was available for 464 patients, with successful RNA extraction and CMS subtyping achieved in 390 patients (surgery alone group: 192, adjuvant chemotherapy group: 198). In the overall cohort, CMS4 was associated with poorest prognosis (HR 1.55; p = .03). Multivariate analysis revealed favorable RFS for the adjuvant chemotherapy group in CMS1, CMS2, and CMS4 tumors (HR 0.19; p = .01, HR 0.27; p < .01, HR 0.19; p < .01, respectively), while no significant difference between treatment groups was observed within CMS3 (HR 0.68; p = .51). CMS subtyping in this non‐randomized cohort identified patients with poor prognosis and patients who may not benefit significantly from adjuvant chemotherapy.

BCL-XL is a crucial anti-apoptotic protein that supports survival of intestinal cells during the progression and in established colorectal cancer (CRC). While targeting BCL-XL with BH3 mimetics is effective, its significant toxicity highlights the need for alternative approaches. Importantly, the early steps in intestinal transformation are marked by a competition between normal and transformed stem cells in which the mutant cells gain a supercompetitive advantage due to the secretion of WNT inhibitors. Using multiple human and murine CRC models, we revealed that GSK-3 inhibition strongly sensitized to BH3 mimetic-induced killing. As expected, GSK-3 inhibition significantly upregulated the WNT pathway, but also led to marked enhancement of BH3 mimetic-induced apoptosis, as measured by mitochondrial BAX aggregation, Caspase-3 activation and Propidium Iodide exclusion. Furthermore, GSK-3 inhibition provided an advantage to wild-type intestinal organoids in competition with APC-mutant counterparts due to reactivation of the WNT pathway. More strikingly, combining GSK-3 and BCL-XL inhibition profoundly affected the supercompetition APC-mutant intestinal cells exert over the wild-types. In effect, the combination therapy enhanced the competitive fitness of wild-type cells and resulted in the killing of APC-mutant organoids, pointing to a novel combination therapy that can be further exploited in the treatment of adenomas and CRC.