Large-scale N-terminal deletions but not point mutations stabilize beta-catenin in small bowel carcinomas, suggesting divergent molecular pathways of small and large intestinal carcinogenesis

Clinical practice guidelines for duodenal cancer 2021

Duodenal cancer is considered to be a small intestinal carcinoma in terms of clinicopathology. In Japan, there are no established treatment guidelines based on sufficient scientific evidence; therefore, in daily clinical practice, treatment is based on the experience of individual physicians. However, with advances in diagnostic modalities, it is anticipated that opportunities for its detection will increase in future. We developed guidelines for duodenal cancer because this disease is considered to have a high medical need from both healthcare providers and patients for appropriate management. These guidelines were developed for use in actual clinical practice for patients suspected of having non-ampullary duodenal epithelial malignancy and for patients diagnosed with non-ampullary duodenal epithelial malignancy. In this study, a practice algorithm was developed in accordance with the Minds Practice Guideline Development Manual 2017, and Clinical Questions were set for each area of epidemiology and diagnosis, endoscopic treatment, surgical treatment, and chemotherapy. A draft recommendation was developed through a literature search and systematic review, followed by a vote on the recommendations. We made decisions based on actual clinical practice such that the level of evidence would not be the sole determinant of the recommendation. This guideline is the most standard guideline as of the time of preparation. It is important to decide how to handle each case in consultation with patients and their family, the treating physician, and other medical personnel, considering the actual situation at the facility (and the characteristics of the patient).

Small bowel adenocarcinoma in Crohn's disease: a systematic review and meta-analysis of the prevalence, manifestation, histopathology, and outcomes

BACKGROUND AND AIMS

Small bowel adenocarcinoma (SBA) is a rare neoplasm that is associated with Crohn's disease (CD). This study aims to quantify the prevalence of CD-SBA, review the current evidence of histopathology and molecular analysis findings, and identify the clinical presentation and outcomes of CD-SBA.

METHODS

Electronic databases Medline and Embase were searched for articles describing SBA in inflammatory bowel disease patients. The histopathology, molecular analysis findings, clinical presentation, prevalence, and outcomes of CD-SBA were extracted, and results were pooled with random effects.

RESULTS

In total, 33 articles were included in the analysis. Prevalence of SBA was 1.15 (CI: 0.31-2.33) per 1000 CD patients. Only 11% (CI: 0.04-0.21) of CD-SBA patients had observable radiological features. CD-SBA was most commonly found in the ileum (84%), diagnosed at stage 2 (36%), with main presenting complaints including obstruction, weight loss, and abdominal pain. Significant histopathological findings included adjacent epithelial dysplasia, and an equal distribution of well-differentiated (49%) and poorly differentiated subtypes (46%). Most prevalent genetic mutation was KRAS mutation (18%), followed by mismatch repair deficiency (9.7%). The 5-year overall survival for CD-SBA patients was 29% (CI: 0.18-0.41), and 33% (CI: 0.26-0.41) for de novo SBA. No statistically significant increase in risk for CD-SBA was noted for treatment with thiopurines, steroids, and 5-ASA.

CONCLUSION

Our meta-analysis found the prevalence of CD-SBA to be 1.15 per 1000 CD patients. The 5-year overall survival for CD-SBA was poor. The presenting symptoms were non-specific, and therefore the diagnosis requires a high index of suspicion.

Epidemiology of Cancers of the Small Intestine: Trends, Risk Factors, and Prevention

The latest data from the United States and Europe reveal that rare small intestine cancer is on the rise, with the number of cases having more than doubled over the past 40 years in the developed world. Mortality has grown at a slower pace, thanks to improvements in early diagnosis and treatment, as well as a shift in the etiology of neoplasms affecting the small intestine. Nevertheless, 5-year survival for small intestine adenocarcinomas has lingered at only 35%. Lifestyle in developed nations, including the rise in obesity and physical inactivity, consumption of alcohol, tobacco, and red and processed meats, and occupational exposures may be to blame for the proliferation of this rare cancer. Identification of hereditary and predisposing conditions, likely to blame for some 20% of cases, may help prevent and treat cancers of the small intestine. Studies of the neoplasm have been limited by small sample sizes due to the rarity of the disease, leaving many questions about prevention and treatment yet to be answered.

Novel intra-genic large deletions of CTNNB1 gene identified in WT desmoid-type fibromatosis

A wait and see approach for desmoid tumors (DT) has become part of the routine treatment strategy. However, predictive factors to select the risk of progressive disease are still lacking. A translational project was run in order to identify genomic signatures in patients enrolled within an Italian prospective observational study. Among 12 DT patients (10 CTNNB1-mutated and 2 wild type) enrolled from our institution only two patients (17%) showed a progressive disease. Tumor biopsies were collected for whole exome sequencing. Overall, DT exhibited low somatic sequence mutation rate and no additional recurrent mutation was found. In the two wild type (WT) cases, two novel alterations were detected: a complex deletion of APC and a pathogenic mutation of LAMTOR2. Focusing on WT DT subtype, deep sequencing of CTNNB1, APC and LAMTOR2 was conducted on a retrospective series of 11 WT DT using a targeted approach. No other mutation of LAMTOR2 was detected, while APC was mutated in two cases. Low-frequency (mean reads of 16%) CTNNB1 mutations were discovered in five samples (45%) and two novel intra-genic deletions in CTNNB1 were detected in two cases. Both deletions and low frequency mutations of CTNNB1 were highly expressed. In conclusion, a minority of DT is WT for either CTNNB1, APC or any other gene involved in the WNT pathway. In this subgroup novel and hard to be detected molecular alterations in APC and CTNNB1 were discovered, contributing to explain a portion of the allegedly WT DT cases.

Small bowel carcinomas in celiac or Crohn's disease: distinctive histophenotypic, molecular and histogenetic patterns

Non-familial small bowel carcinomas are relatively rare and have a poor prognosis. Two small bowel carcinoma subsets may arise in distinct immune-inflammatory diseases (celiac disease and Crohn's disease) and have been recently suggested to differ in prognosis, celiac disease-associated carcinoma cases showing a better outcome, possibly due to their higher DNA microsatellite instability and tumor-infiltrating T lymphocytes. In this study, we investigated the histological structure (glandular vs diffuse/poorly cohesive, mixed or solid), cell phenotype (intestinal vs gastric/pancreatobiliary duct type) and Wnt signaling activation (β-catenin and/or SOX-9 nuclear expression) in a series of 26 celiac disease-associated small bowel carcinoma, 25 Crohn's disease-associated small bowel carcinoma and 25 sporadic small bowel carcinoma cases, searching for new prognostic parameters. In addition, non-tumor mucosa of celiac and Crohn's disease patients was investigated for epithelial precursor changes (hyperplastic, metaplastic or dysplastic) to help clarify carcinoma histogenesis. When compared with non-glandular structure and non-intestinal phenotype, both glandular structure and intestinal phenotype were associated with a more favorable outcome at univariable or stage- and microsatellite instability/tumor-infiltrating lymphocyte-inclusive multivariable analysis. The prognostic power of histological structure was independent of the clinical groups while the non-intestinal phenotype, associated with poor outcome, was dominant among Crohn's disease-associated carcinoma. Both nuclear β-catenin and SOX-9 were preferably expressed among celiac disease-associated carcinomas; however, they were devoid, per se, of prognostic value. We obtained findings supporting an origin of celiac disease-associated carcinoma in SOX-9-positive immature hyperplastic crypts, partly through flat β-catenin-positive dysplasia, and of Crohn's disease-associated carcinoma in a metaplastic (gastric and/or pancreatobiliary-type) mucosa, often through dysplastic polypoid growths of metaplastic phenotype. In conclusion, despite their common origin in a chronically inflamed mucosa, celiac disease-associated and Crohn's disease-associated small bowel carcinomas differ substantially in histological structure, phenotype, microsatellite instability/tumor-infiltrating lymphocyte status, Wnt pathway activation, mucosal precursor lesions and prognosis.

Βeta-catenin N-terminal domain: An enigmatic region prone to cancer causing mutations

The Wnt/β-catenin is a highly conserved signaling pathway involved in cell fate decisions during various stages of development. Dysregulation of canonical Wnt/β-catenin signaling has been associated with various diseases including cancer. β-Catenin, the central component of canonical Wnt signaling pathway, is a multi-functional protein playing both structural and signaling roles. β-Catenin is composed of three distinct domains: N-terminal domain, C-terminal domain and a central armadillo repeat domain. N-terminal domain of β-catenin harbours almost all of the cancer causing mutations, thus deciphering its critical structural and functional roles offers great potential in cancer detection and therapy. Here, in this review, we have collected information from pharmacological analysis, bio-physical and structural studies, molecular modeling, in-vivo and in-vitro assays, and transgenic animal experiments employing various N-terminal domain variants of β-catenin to discuss the interaction of β-catenin with its binding partners that specifically interact with this domain and the implications of these interactions on signaling, cell fate determination, and in tumorigenesis. A thorough understanding of interactions between β-catenin and its binding partners will enable us to more effectively understand how β-catenin switches between its multiple roles, and will lead to the development of specific assays for the identification of small molecules as chemotherapeutic agents to treat diseases, including cancer and neurological disorders, where Wnt/β-catenin signaling is dysregulated.

Small Bowel Adenocarcinoma

Small bowel adenocarcinomas (SBAs) are rare tumors, but their incidence is increasing. The most common primary location is the duodenum. Even though SBAs are more often sporadic, some diseases are risk factors. Early diagnosis of small bowel adenocarcinoma remains difficult, despite significant radiologic and endoscopic progress. After R0 surgical resection, the main prognostic factor is lymph node invasion. An international randomized trial (BALLAD [Benefit of Adjuvant Chemotherapy For Small Bowel Adenocarcinoma] study) will evaluate the benefit of adjuvant chemotherapy. For metastatic disease, retrospectives studies suggest that platinum-based chemotherapy is the most effective treatment. Phase II studies are ongoing to evaluate targeted therapy in metastatic SBA.

Characterization of a new small bowel adenocarcinoma cell line and screening of anti-cancer drug against small bowel adenocarcinoma

Small bowel adenocarcinoma (SBA) is a rare, aggressive malignancy with a poor prognosis, and the mechanisms of carcinogenesis in SBA remain unclear. Our aims were to investigate the molecular mechanisms underlying SBA and to identify treatments by establishing and characterizing an SBA cell line and performing anti-cancer drug screening. SIAC1 cells, established from jejunal SBA, showed epithelial characteristics and formed organoids in 3D culture. SIAC1 cells had a heterozygous β-catenin deletion mutation, resulting in a stable β-catenin protein with enhanced Wnt/β-catenin activity. SIAC1 cells lacked MLH1 and MSH6 expression, and target genes such as TGFBR2 and ACVR2 showed frameshift mutations. Among 10 clinical SBA samples, 2 (20%) had interstitial deletions in β-catenin, expression of mismatch repair protein was aberrant in 4 (40%), and heterozygous frameshift mutations of three target genes were found in all 10 samples. On screening assay using 140 compounds, eribulin significantly inhibited SIAC1 cell growth both in vitro and in vivo by inhibition of the Wnt/β-catenin pathway via enhanced degradation of β-catenin. In conclusion, we established an SBA cell line with molecular characteristics similar to those of clinical SBA samples, including β-catenin deletion and mismatch repair protein deficiency, that will be useful for SBA research. Eribulin might be a candidate for SBA treatment due to its inhibitory effect on Wnt/β-catenin signaling.

Small bowel adenocarcinoma: epidemiology, risk factors, diagnosis and treatment

Small bowel adenocarcinomas are rare tumours, but their incidence is increasing. Their most common primary location is the duodenum. The few studies that have collected data regarding small bowel adenocarcinoma are not homogeneous and are widely spread over time. Even though these tumours are most often sporadic, some predisposing diseases have been identified, among which Crohn's disease and genetic syndromes. Early diagnosis of small bowel adenocarcinoma remains difficult despite significant radiological and endoscopic progress. After surgical resection the main prognostic factor is node invasion; in this case, adjuvant chemotherapy can be expected to be beneficial, although this has not been established by randomised trials. For metastatic disease, platinum-based chemotherapy seems to be the most effective treatment. Targeted therapies have not yet been evaluated in this type of cancer.

Small bowel adenocarcinomas--existing evidence and evolving paradigms

Small bowel cancers account for 3% of all gastrointestinal malignancies and small bowel adenocarcinomas represent a third of all small bowel cancers. Rarity of small bowel adenocarcinomas restricts molecular understanding and presents unique diagnostic and therapeutic challenges. Better cross-sectional imaging techniques and development of enteroscopy and capsule endoscopy have facilitated earlier and more-accurate diagnosis. Surgical resection remains the mainstay of therapy for locoregional disease. In the metastatic setting, fluoropyrimidine and oxaliplatin-based chemotherapy has shown clinical benefit in prospective non-randomized trials. Although frequently grouped under the same therapeutic umbrella as large bowel adenocarcinomas, small bowel adenocarcinomas are distinct clinical and molecular entities. Recent progress in molecular characterization has aided our understanding of the pathogenesis of these tumours and holds potential for prospective development of novel targeted therapies. Multi-institutional collaborative efforts directed towards cogent understanding of tumour biology and designing sensible clinical trials are essential for developing improved therapeutic strategies. In this Review, we endeavour to outline an evidence-based approach to present-day management of small bowel adenocarcinoma, describe contemporary challenges and uncover evolving paradigms in the management of these rare 'orphan' neoplasias.

Combined loss of E-cadherin and aberrant β-catenin protein expression correlates with a poor prognosis for small intestinal adenocarcinomas

Small intestinal adenocarcinomas (SIACs) are rare, and their molecular pathogenesis is largely unknown. To define the roles of E-cadherin and β-catenin, we performed immunohistochemistry for E-cadherin and β-catenin in 194 surgically resected SIACs with tissue microarrays and compared the data with clinicopathologic factors, including survival rates of patients with SIAC. Loss of E-cadherin expression and aberrant β-catenin expression were observed in 41.8% (81/194 cases) and 40.7% (79/194 cases) of SIACs, respectively. Combined loss of E-cadherin and aberrant β-catenin expression was observed in 24.2% (47/194 cases) of SIACs, and this feature was most frequently observed in mucinous adenocarcinomas and signet ring cell carcinomas (P < .001), poorly differentiated and undifferentiated carcinomas (P < .001), and tumors with advanced pT classification (P = .03). Survival times for patients with SIAC with both loss of E-cadherin and aberrant β-catenin expression (median, 13.9 months) were significantly shorter than those for patients without aberrant expression of both proteins (49.9 months), as determined by univariate (P < .001) and multivariate (P = .01) analyses. In conclusion, loss of E-cadherin and aberrant β-catenin expression correlate with poorly differentiated tumors, advanced T classification, and decreased patient survival time; therefore, it could be a prognostic factor in patients with SIAC.

[Chromosomal instability, microsatellite instability and CpG island methylator phenotype: roles in small intestinal carcinogenesis]

AIMS

Intestinal carcinogenesis is associated with genetic instability affecting either the chromosomal level (CIN) or microsatellite DNA sequences (MIN). In addition, epigenetic alterations, such as aberrant CpG island methylation (CIMP) may contribute to tumor development. While these single genetic alterations have frequently been addressed in intestinal carcinogenesis little is known about the interaction of the epigenetics and genetics in tumorigenesis. This investigation therefore aimed to define the synergistic effects of CIN, MSI and CIMP in small bowel adenocarcinomas.

METHODS

A total of 37 primary small bowel adenocarcinomas were investigated for CIN, MSI, CIMP, KRAS and BRAF mutations. The results showed that CIN was found in 22 out of 37 (57%) tumors (3 out of 9 microsatellite instable and 19 out of 28 microsatellite stable carcinomas) and 9 carcinomas (24%) were microsatellite and chromosomally stable. Aberrant CIMP was detected in 16% of chromosomal instable tumors and in 44% of both microsatellite instable and microsatellite and chromosomally stable carcinomas, KRAS was mutated in 55%, 0% and 10% of chromosomal instable, microsatellite instable and microsatellite and chromosomal stable tumors, respectively, while BRAF mutations occurred in 6% of chromosomal instable and 22% of both microsatellite instable and microsatellite and chromosomal stable carcinomas.

CONCLUSION

Chromosomal instable carcinomas of the small intestine are distinguished from microsatellite instable and microsatellite and chromosomal stable tumors by a high frequency of KRAS mutations and low frequencies of CIMP and BRAF mutations. In microsatellite instable and microsatellite and chromosomally stable cancers, CIMP and BRAF/KRAS mutations are similarly distributed indicating common mechanisms of tumor initiation or progression in the molecular pathogenesis.

Colorectal cancers choosing sides

In contrast to the majority of sporadic colorectal cancer which predominantly occur in the distal colon, most mismatch repair deficient tumours arise at the proximal side. At present, these regional preferences have not been explained properly. Recently, we have screened colorectal tumours for mutations in Wnt-related genes focusing specifically on colorectal location. Combining this analysis with published data, we propose a mechanism underlying the side-related preferences of colorectal cancers, based on the specific acquired genetic defects in β-catenin signalling.

β-catenin dosage is a critical determinant of tracheal basal cell fate determination

The purpose of this study was to determine whether β-catenin regulates basal cell fate determination in the mouse trachea. Analysis of TOPGal transgene reporter activity and Wnt/β-catenin pathway gene expression suggested a role for β-catenin in basal cell proliferation and differentiation after naphthalene-mediated Clara-like and ciliated cell depletion. However, these basal cell activities occurred simultaneously, limiting precise determination of the role(s) played by β-catenin. This issue was overcome by analysis of β-catenin signaling in tracheal air-liquid interface cultures. The cultures could be divided into two phases: basal cell proliferation and basal cell differentiation. A role for β-catenin in basal cell proliferation was indicated by activation of the TOPGal transgene on proliferation days 3 to 5 and by transient expression of Myc (alias c-myc). Another peak of TOPGal transgene activity was detected on differentiation days 2 to 10 and was associated with the expression of Axin 2. These results suggest a role for β-catenin in basal to ciliated and basal to Clara-like cell differentiation. Genetic stabilization of β-catenin in basal cells shortened the period of basal cell proliferation but had a minor effect on this process. Persistent β-catenin signaling regulated basal cell fate by driving the generation of ciliated cells and preventing the production of Clara-like cells.

Genetics and epigenetics of small bowel adenocarcinoma: the interactions of CIN, MSI, and CIMP

Characterization of tumor genetics and epigenetics allows to stratify a tumor entity according to molecular pathways and may shed light on the interactions of different types of DNA alterations during tumorigenesis. Small intestinal adenocarcinoma is rare, and to date the interrelation of genomic instability and epigenetics has not been investigated in this tumor type. We therefore analyzed 37 primary small bowel carcinomas with known microsatellite instability and KRAS status for chromosomal instability using comparative genomic hybridization, for the presence of aberrant methylation (CpG island methylation phenotype) by methylation-specific polymerase chain reaction, and for BRAF mutations. Chromosomal instability was detected in 22 of 37 (59%) tumors (3 of 9 microsatellite instable, and 19 of 28 microsatellite stable carcinomas). Nine carcinomas (24%) were microsatellite and chromosomally stable. High-level DNA methylation was found in 16% of chromosomal instable tumors and in 44% of both microsatellite instable and microsatellite and chromosomally stable carcinomas. KRAS was mutated in 55, 0, and 10% of chromosomal instable, microsatellite instable, and microsatellite and chromosomally stable tumors, respectively whereas the frequencies of BRAF mutations were 6% for chromosomal instable and 22% for both microsatellite instable and microsatellite and chromosomally stable carcinomas. In conclusion, in this study we show that chromosomal instable carcinomas of the small intestine are distinguished from microsatellite instable and microsatellite and chromosomally stable tumors by a high frequency of KRAS mutations, low frequencies of CpG island methylation phenotype, and BRAF mutations. In microsatellite instable and microsatellite and chromosomally stable cancers, CpG island methylation phenotype and BRAF/KRAS mutations are similarly distributed, indicating common mechanisms of tumor initiation or progression in their molecular pathogenesis.

Cytoplasmic beta-catenin accumulation is a good prognostic marker in upper and lower gastrointestinal adenocarcinomas

AIMS

beta-Catenin is an important molecule in cancer biology. Membranous beta-catenin enhances cellular differentiation and inhibits invasion by its action on E-cadherin. The aim was to ascertain whether the cellular expression of these molecules in colorectal and oesophageal cancer specimens is associated with survival in patients with gastrointestinal cancer.

METHODS AND RESULTS

Tumour samples from 149 patients undergoing resection for colorectal adenocarcinoma and 147 patients undergoing resection for oesophageal adenocarcinoma were retrospectively analysed using immunohistochemical techniques to assess beta-catenin expression. Increasing beta-catenin expression in the cytoplasm was associated with improved survival for colorectal cancer cases on both univariate (P = 0.003) and multivariate (P = 0.01) analysis. In addition, increased expression in the most recent cohort of oesophageal adenocarcinoma patients was associated with improved TNM staging (P = 0.007). Membrane expression was weakly associated with survival in colorectal cancer on univariate analysis (P = 0.09), but not on multivariate analysis (P = 0.21). Complete absence of beta-catenin expression at all three sites was associated with reduced 5-year survival in colorectal cancer.

CONCLUSIONS

This is one of the largest prognostic studies of beta-catenin in gastrointestinal adenocarcinoma. It shows that low levels of cytoplasmic beta-catenin expression are associated with reduced survival in patients with colorectal cancer as well as worse TNM staging in oesophageal adenocarcinoma (a recognized surrogate end-point for survival). We believe this is the first time that this has been reported. This finding should be tested prospectively in oncological trials to validate whether the presence of cytoplasmic beta-catenin could be used as a prognostic marker for less aggressive disease.