Colorectal carcinoma tumour budding and podia formation in the xenograft microenvironment

Prognostic significance of tumor budding in melanoma

Cutaneous melanoma is an aggressive neoplasm with growing incidence and continuous research is undertaken for novel prognostic factors. This current research aims to determine if tumor budding is an independent factor that correlates with the survival of patients with melanoma. A total of 742 cases of melanoma were evaluated. A receiver operating curve (ROC) was performed to analyze tumor budding impact on survival, identifying a cutoff point associated with death. Subsequently, two groups of participants were created based on that result. Participants within the two groups were compared for clinicopathologic characteristics and survival analysis. Also, a multivariate analysis was performed. Of the total, 447 (60.2%) melanomas occurred in women and 295 in men. The mean age was 57.5 years + 15.75. The most common location was in acral areas (68.2%) followed by trunk (16.7%) and head and neck (15.1%). At presentation, 142 cases (19.1%) presented as stage I, 307 (41.4%) as stage II, 269 (36.3%) as stage III, and 24 (3, 2%) in stage IV. Regarding tumor budding, 586 (79%) cases showed tumor budding (at least one bud in 0.785 mm2), with a median of 5. From the ROC curve, 4.5 tumor buds/0.785 mm2 was the best cutoff point for correlation with death, grouping the series in low budding (0-4 buds/0.785 mm2) and high budding (>5 buds/0.785 mm2). Cases with high tumor budding were associated with older age, acral location, advanced clinical stages, ulceration, recurrence, and death. High tumor budding was associated with a significant decrease in 5-year overall survival (94.4% vs. 55.5%, P < 0.001). In the multivariate analysis, the factors remaining as independent predictors of survival were acral location, clinical stage IV, recurrence during clinical follow-up, and high tumor budding. High tumor budding (>5 buds in 0.785 mm2) independently correlates with 5-year overall survival rates and is associated with older age, acral location, advanced clinical stages, ulceration, recurrence, and death.

Bridging the Species Gap: Morphological and Molecular Comparison of Feline and Human Intestinal Carcinomas

Simple Summary

Colorectal cancer (CRC) is the second leading cause of cancer deaths in humans (2020) but modeling late-stage human CRC, including high tumor budding and metastatic activity, experimentally in mouse models is a major challenge. In the present study, histopathological, immunohistochemical and molecular features of spontaneous intestinal carcinomas in cats were evaluated with a special focus on their potential applicability as a valuable model for human CRC. Feline intestinal tumors display aggressive growth patterns and adequately model invasive late-stage human CRC. They exhibit the same histological subtypes and display strikingly high tumor budding activity, both of which are highly significant prognostic factors in human CRC. Moreover, human and feline colorectal tumors harbor the same mutations of the CTNNB1 gene, encoding β-catenin. Our data indicate that feline intestinal carcinomas constitute a valuable and promising in vivo model for human CRC. Further comparative oncological research, and especially investigation of the molecular landscape of feline intestinal neoplasms, is imperative.

Abstract

Limited availability of in vivo experimental models for invasive colorectal cancer (CRC) including metastasis and high tumor budding activity is a major problem in colorectal cancer research. In order to compare feline and human intestinal carcinomas, tumors of 49 cats were histologically subtyped, graded and further characterized according to the human WHO classification. Subsequently, feline tumors were compared to a cohort of 1004 human CRC cases. Feline intestinal tumors closely resembled the human phenotype on a histomorphological level. In both species, adenocarcinoma not otherwise specified (ANOS) was the most common WHO subtype. In cats, the second most common subtype of the colon (36.4%), serrated adenocarcinoma (SAC), was overrepresented compared to human CRC (8.7%). Mucinous adenocarcinoma (MAC) was the second most common subtype of the small intestine (12.5%). Intriguingly, feline carcinomas, particularly small intestinal, were generally of high tumor budding (Bd) status (Bd3), which is designated an independent prognostic key factor in human CRC. We also investigated the relevance of feline CTNNB1 exon 2 alterations by Sanger sequencing. In four cases of feline colonic malignancies (3 ANOS, 1 SAC), somatic missense mutations of feline CTNNB1 (p.D32G, p.D32N, p.G34R, and p.S37F) were detected, indicating that mutational alterations of the WNT/β-catenin signaling pathway potentially play an essential role in feline intestinal tumorigenesis comparable to humans and dogs. These results indicate that spontaneous intestinal tumors of cats constitute a useful but so far underutilized model for human CRC. Our study provides a solid foundation for advanced comparative oncology studies and emphasizes the need for further (molecular) characterization of feline intestinal carcinomas.

The HROC-Xenobank-A High Quality Assured PDX Biobank of >100 Individual Colorectal Cancer Models

Simple Summary

Considering recent research, it was established that the best experimental models to conserve biological features of human tumors and to predict individual clinical treatment success are patient-derived xenografts (PDX). Their recognized and growing importance for translational research, especially for late-stage preclinical testing of novel therapeutics, necessitates a high number of well-defined PDX models from individual patients’ tumors. The starting platform for the Hansestadt Rostock colorectal cancer (HROC)-Xenobank was the assortment of colorectal tumor and normal tissue samples from patients stored in our university biobank.

Abstract

Based on our research group’s large biobank of colorectal cancers (CRC), we here describe the ongoing activity of establishing a high quality assured PDX biobank for more than 100 individual CRC cases. This includes sufficient numbers of vitally frozen (n > 30 aliquots) and snap frozen (n > 5) backups, “ready to use”. Additionally, PDX tumor pieces were paraffin embedded. At the current time, we have completed 125 cases. This resource allows histopathological examinations, molecular characterizations, and gene expression analysis. Due to its size, different issues of interest can be addressed. Most importantly, the application of low-passage, cryopreserved, and well-characterized PDX for in vivo studies guarantees the reliability of results due to the largely preserved tumor microenvironment. All cases described were molecularly subtyped and genetic identity, in comparison to the original tumor tissue, was confirmed by fingerprint analysis. The latter excludes ambiguity errors between the PDX and the original patient tumor. A cancer hot spot mutation analysis was performed for n = 113 of the 125 cases entities. All relevant CRC molecular subtypes identified so far are represented in the Hansestadt Rostock CRC (HROC)-Xenobank. Notably, all models are available for cooperative research approaches.

Diagnostic value of syndecan-4 protein expression in colorectal cancer

The prognosis of patients with colorectal cancer (CRC) is highly dependent on the disease stage at diagnosis. Therefore, it is crucial to study molecules involved in the progression of colorectal cancer tumorigenesis and to shed light on their potential use as targetable proteins in diagnostics and therapy. As syndecan-4 (SDC4) is a transmembrane proteoglycan with important functions in cell adhesion, migration, cytoskeleton organization, and gene expression through the binding of extracellular matrix molecules, it might play a role in local tumor cell invasion. To clarify its impact on the progression of CRC, we analyzed 177 patients for SDC4 expression in colon carcinoma tissue, lymph node and liver metastasis under consideration of specific morphological features and cellular elements of CRC. Highly upregulated SDC4 was particularly expressed at the tumor invasion front. Expression was strongest in tumor cell buds appearing as membranous expression polarized to peritumoral stromal cells. Increased SDC4 expression directed to the tumor-stromal- or tumor-endothelial-interface was also confirmed for metastasis and angioinvasive tumor cell clusters. Furthermore, strong immunoreactivity of SDC4 in fibroblasts and macrophages being in contact with invasive tumor cells suggests a cooperation between the different types of cells in tumor progression at the cell-matrix interface and a role for SDC4 in tumor cells attached to the extracellular matrix. Overexpression of SDC4 in tumor cells at the invasion front was significantly associated with progressive pathological features and inversely related to disease-free and overall survival. Therefore, overexpression of SDC4 may be a predictor for poor prognosis in patients with CRC and might prove useful in clinical practice, thus identifying patients with potential disease progression. Further investigations will have to reveal the functional role of SDC4 in tumor cell buds, fibroblasts and macrophages at the tumor stromal interface to confirm that SDC4 might also be a possible therapeutic target for the treatment of patients with advanced CRC.

Association of Tumor Budding With Immune Evasion Pathways in Primary Colorectal Cancer and Patient-Derived Xenografts

Tumor budding has been found to be of prognostic significance for several cancers, including colorectal cancer (CRC). Additionally, the molecular classification of CRC has led to the identification of different immune microenvironments linked to distinct prognosis and therapeutic response. However, the association between tumor budding and the different molecular subtypes of CRC and distinct immune profiles have not been fully elucidated. This study focused, firstly, on the validation of derived xenograft models (PDXs) for the evaluation of tumor budding and their human counterparts and, secondly, on the association between tumor budding and the immune tumor microenvironment by the analysis of gene expression signatures of immune checkpoints, Toll-like receptors (TLRs), and chemokine families. Clinical CRC samples with different grades of tumor budding and their corresponding PDXs were included in this study. Tumor budding grade was reliably reproduced in early passages of PDXs, and high-grade tumor budding was intimately related with a poor-prognosis CMS4 mesenchymal subtype. In addition, an upregulation of negative regulatory immune checkpoints (PDL1, TIM-3, NOX2, and IDO1), TLRs (TLR1, TLR3, TLR4, and TLR6), and chemokine receptors and ligands (CXCR2, CXCR4, CXCL1, CXCL2, CXCL6, and CXCL9) was detected in high-grade tumor budding in both human samples and their corresponding xenografts. Our data support a close link between high-grade tumor budding in CRC and a distinctive immune-suppressive microenvironment promoting tumor invasion, which may have a determinant role in the poor prognosis of the CMS4 mesenchymal subtype. In addition, our study demonstrates that PDX models may constitute a robust preclinical platform for the development of novel therapies directed against tumor budding in CRC.

Mouse models of colorectal cancer: Past, present and future perspectives

Colorectal cancer (CRC) is the third most common diagnosed malignancy among both sexes in the United States as well as in the European Union. While the incidence and mortality rates in western, high developed countries are declining, reflecting the success of screening programs and improved treatment regimen, a rise of the overall global CRC burden can be observed due to lifestyle changes paralleling an increasing human development index. Despite a growing insight into the biology of CRC and many therapeutic improvements in the recent decades, preclinical in vivo models are still indispensable for the development of new treatment approaches. Since the development of carcinogen-induced rodent models for CRC more than 80 years ago, a plethora of animal models has been established to study colon cancer biology. Despite tenuous invasiveness and metastatic behavior, these models are useful for chemoprevention studies and to evaluate colitis-related carcinogenesis. Genetically engineered mouse models (GEMM) mirror the pathogenesis of sporadic as well as inherited CRC depending on the specific molecular pathways activated or inhibited. Although the vast majority of CRC GEMM lack invasiveness, metastasis and tumor heterogeneity, they still have proven useful for examination of the tumor microenvironment as well as systemic immune responses; thus, supporting development of new therapeutic avenues. Induction of metastatic disease by orthotopic injection of CRC cell lines is possible, but the so generated models lack genetic diversity and the number of suited cell lines is very limited. Patient-derived xenografts, in contrast, maintain the pathological and molecular characteristics of the individual patient’s CRC after subcutaneous implantation into immunodeficient mice and are therefore most reliable for preclinical drug development – even in comparison to GEMM or cell line-based analyses. However, subcutaneous patient-derived xenograft models are less suitable for studying most aspects of the tumor microenvironment and anti-tumoral immune responses. The authors review the distinct mouse models of CRC with an emphasis on their clinical relevance and shed light on the latest developments in the field of preclinical CRC models.

RAS, Cellular Plasticity, and Tumor Budding in Colorectal Cancer

The high morbidity and mortality of colorectal cancer (CRC) remain a worldwide challenge, despite the advances in prevention, diagnosis, and treatment. RAS alterations have a central role in the pathogenesis of CRC universally recognized both in the canonical mutation-based classification and in the recent transcriptome-based classification. About 40% of CRCs are KRAS mutated, 5% NRAS mutated, and only rare cases are HRAS mutated. Morphological and molecular correlations demonstrated the involvement of RAS in cellular plasticity, which is related to invasive and migration properties of neoplastic cells. RAS signaling has been involved in the initiation of epithelial to mesenchymal transition (EMT) in CRC leading to tumor spreading. Tumor budding is the morphological surrogate of EMT and features cellular plasticity. Tumor budding is clinically relevant for CRC patients in three different contexts: (i) in pT1 CRC the presence of tumor buds is associated with nodal metastasis, (ii) in stage II CRC identifies the cases with a prognosis similar to metastatic disease, and (iii) intratumoral budding could be useful in patient selection for neoadjuvant therapy. This review is focused on the current knowledge on RAS in CRC and its link with cellular plasticity and related clinicopathological features.

Integrated Biobanking and Tumor Model Establishment of Human Colorectal Carcinoma Provides Excellent Tools for Preclinical Research

Over the time period from 2006 to 2017, consecutive patients operated on at the University Medical Center Rostock participated in the comprehensive biobanking and tumor-modelling approach known as the HROC collection. Samples were collected using strict standard operating procedures including blood (serum and lymphocytes), tumor tissue (vital and snap frozen), and adjacent normal epithelium. Patient and tumor data including classification, molecular type, clinical outcome, and results of the model establishment are the essential pillars. Overall, 149 patient-derived xenografts with 34 primary and 35 secondary cell lines were successfully established and encompass all colorectal carcinoma anatomic sites, grading and staging types, and molecular classes. The HROC collection represents one of the largest model assortments from consecutive clinical colorectal carcinoma (CRC) cases worldwide. Statistical analysis identified a variety of clinicopathological and molecular factors associated with model success in univariate analysis. Several of them not identified before include localization, mutational status of K-Ras and B-Raf, MSI-status, and grading and staging parameters. In a multivariate analysis model, success solely correlated positively with the nodal status N1 and mutations in the genes K-Ras and B-Raf. These results imply that generating CRC tumor models on the individual patient level is worth considering especially for advanced tumor cases with a dismal prognosis.

Cell Line Derived Xenograft Mouse Models Are a Suitable in vivo Model for Studying Tumor Budding in Colorectal Cancer

Tumor budding (TB) is an important prognostic parameter in colorectal cancer (CRC) and associated with metastasis. However, the mechanisms of TB have not been fully elucidated and a major limitation is the absence of in vivo models. Here, we determine the suitability of human cell line derived xenografts (CDX) as models of TB in CRC. Pan-cytokeratin (CK)-stained next-generation Tissue Microarrays (ngTMA) of two CDX models (HT-29, n = 12 and HCT-8, n = 8) and human CRC (n = 27 high-grade and 25 low-grade budding tumors, each) were evaluated for TB. Immunohistochemistry for E-cadherin, β-catenin, Ki-67, ZEB1, and TWIST1 was performed. HT-29 and HCT-8 were predominantly high-grade and no/low-grade TB tumors, respectively. TB counts in the tumor center (intratumoral budding, ITB) were significantly higher in HT-29 CDX tumors compared to human CRC (p = 0.0099). No difference was found in TB counts at the invasion front (peritumoral budding, PTB; p=0.07). ITB and PTB were strongly correlated (r = 0.438 and r = 0.62 in CDX and human CRC, respectively). Immunohistochemistry profiles were comparable in CDX and human CRC tissues. TB in the CDX mouse models is phenotypically similar to human CRCs and highlights comparable protein profiles. The HT-29 CDX could be a suitable model for the in vivo assessment of TB.

Tumour budding in rectal cancer. A comprehensive review

A unique and fundamental characteristic of malignant neoplastic cells is their ability to invade other tissues and metastasise. The first step in this process is the dissociation of some of these cells from the tumour invasion front, named tumour budding (TB). This phenomenon has become increasingly relevant in recent years due to its association with adverse clinicopathological characteristics and with the epithelial-mesenchymal transition. TB has been studied by mixing colon with rectal tumours, but it is clinically important to differentiate these types of tumours. A review in two databases without language restriction was performed from 1950 to 2017 about TB with an emphasis on rectal cancer. We present various aspects of TB, from its terminology and evaluation to its molecular aspects, through its clinical associations. TB is associated with adverse clinicopathological features, like lymphovascular invasion, lymph node metastasis, and decreased survival. More studies of the clinicopathological, molecular, and epidemiological characteristics of TB in rectal cancer are needed.