Molecular and biological analysis of carcinoma of the small intestine: beta-catenin gene mutation by interstitial deletion involving exon 3 and replication error phenotype

Gastrointestinal tissue-based molecular biomarkers: a practical categorisation based on the 2019 World Health Organization classification of epithelial digestive tumours

Molecular biomarkers have come to constitute one of the cornerstones of oncological pathology. The method of classification not only directly affects the manner in which patients are diagnosed and treated, but also guides the development of drugs and of artificial intelligence tools. The aim of this article is to organise and update gastrointestinal molecular biomarkers in order to produce an easy-to-use guide for routine diagnostics. For this purpose, we have extracted and reorganised the molecular information on epithelial neoplasms included in the 2019 World Health Organization classification of tumours. Digestive system tumours, 5th edn.

Small bowel adenocarcinoma phenotyping, a clinicobiological prognostic study

BACKGROUND

Small bowel adenocarcinoma (SBA) is a rare tumour with a poor prognosis. Molecular biology data on SBA carcinogenesis are lacking.

METHODS

Expression of HER2, β-catenin, p53 and mismatch repair (MMR) protein was assessed by immunohistochemistry. KRAS, V600E BRAF mutations and microsatellite instability were investigated.

RESULTS

We obtained samples from 63 SBA patients (tumour stages: I-II: 30%; III: 35%; IV: 32%; locally advanced: 3%). HER2 overexpression (3+) was observed in 2 out of 62 patients, overexpression of p53 in 26 out of 62, abnormal expression of β-catenin in 12 out of 61, KRAS mutation in 21 out of 49, BRAF V600E mutation in 1 out of 40 patients, MMR deficiency (dMMR) in 14 out of 61 and was consistent with Lynch syndrome in 9 out of 14 patients. All of the dMMR tumours were in the duodenum or jejunum and only one was stage IV. Median overall survival (OS) was 36.6 months (95% CI, 26.9-72.2). For all patients, in univariate analysis, stages I-II (P<0.001), WHO PS 0-1 (P=0.01) and dMMR phenotype (P=0.02) were significantly associated with longer OS. In multivariate analysis, disease stage (P=0.01) and WHO PS 0-1 (P=0.001) independently predicted longer OS. For stage IV patients, median OS was 20.5 months (95% CI: 14.6; 36.6 months). In multivariate analysis, WHO PS 0-1 (P=0.0001) and mutated KRAS status (P=0.02) independently predicted longer OS.

CONCLUSION

This large study suggests that molecular alterations in SBA are closer to those in colorectal cancer (CRC) than those in gastric cancer, with low levels of HER 2 overexpression and high frequencies of KRAS mutations. The seemingly higher frequency of dMMR than in CRC may be explained by the higher frequency of Lynch syndrome in SBA patients. A dMMR phenotype was significantly associated with a non-metastatic tumour (P=0.02). A trend for a good prognosis and a duodenum or jejunum primary site was associated with dMMR.

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.

TSPAN1 protein expression: A significant prognostic indicator for patients with colorectal adenocarcinoma

AIM: To determine if TSPAN1 overexpression is associated with clinicopathological and prognostic factors in human colorectal adenocarcinoma.

METHODS: Total RNA was extracted in 20 human adenocarcinoma tissues for TSPAN1 mRNA assay by RT-PCR. Eighty-eight specimens of human colorectal adenocarcinoma were surgically removed. TSPAN1 protein levels in cancer tissues were determined by immunohistochemistry using a polyclonal antibody against self-prepared TSPAN1. The correlation between TSPAN1 expression and the clinicopathological factors and the overall survival rate was analyzed by univariate and multivariate assay.

RESULTS: TSPAN1 mRNA was detected in 90.0% (18/20) of cancerous tissues. The light density of TSPAN1 mRNA expression levels was 0.89 ± 0.30 in adenocarcinoma by gel-image system. TSPAN1 protein expression was detected in 78.41% (69/88) and weakly expressed in 40% normal colorectal tissues. There were significant differences between colorectal adenocarcinoma and normal control epithelium (P < 0.05). TSPAN1 protein expression in colorectal cancerous tissue was significantly correlated with the histological grade, cell expression PCNA, lymph nodal metastasis and TNM staging of the disease. Patients with TSPAN1 protein overexpression had a significantly shorter survival period than that in patients with TSPAN1 protein negative or weak expression, respectively (P < 0.05). Furthermore, by multivariate analysis, TSPAN1 protein expression demonstrated an independent prognostic factor for human colorectal cancers (P < 0.05, relative risk 0.755; 95% confidence interval 0.302-1.208).

CONCLUSION: The expression of TSPAN1 gene is increased in colorectal carcinoma, suggesting that TSPAN1 might serve as an independent prognostic factor for the colorectal adenocarcinoma patients.

Association of MDR1 genotypes with susceptibility to colorectal cancer in older non-smokers

OBJECTIVE

The multidrug resistance gene 1 (MDR1) seems to play a role in the carcinogenesis of colorectal tumors. The importance of MDR1 SNPs 2677G > T/A in exon 21 and 3435C > T in exon 26 for cancer susceptibility, however, has not yet been clearly defined.

METHODS

Two hundred and eighty-five colorectal cancer patients and 275 controls from five hospitals in the European part of Russia were genotyped for the polymorphisms -129T > C (rs3213619) in exon 1b, 2677G > T/A (rs2032582), and 3435C > T (rs1045642) in this population-based case-control study. Genotype-phenotype analysis was performed with simultaneous consideration of lifestyle risk factors.

RESULTS

Our analysis confirmed the preponderate impact of smoking on colorectal cancer development. The risk of heavy smokers (>/=60 pack years) to develop colorectal cancer by far exceeded that of lifelong non-smokers (OR = 3.9, 95% CI: 1.4 to 10.6). Smoking is a more potent risk factor than is the genetic influence of MDR1 in our study. However, a smoking and age-stratified analysis, revealed a statistically significant association between MDR1 genotypes and colorectal cancer in life-long non-smokers with an age > or =63 years (the median age in our sample). The association was stronger for rectal cancer than for colon cancer. Patients who carried the genotypes (-129TT; 2677GG; 3435CC) or (-129TT; 2677TT; 3435TT) developed more frequently colorectal cancer than others (OR = 3.9; 95% CI: 2.0 to 7.7).

CONCLUSIONS

Our results show that the interaction of genetic and lifestyle risk factors should be taken into account to elucidate the genetic influence of MDR1 variability on cancer susceptibility.

Genetics of adenocarcinomas of the small intestine: frequent deletions at chromosome 18q and mutations of the SMAD4 gene

The small intestinal mucosa makes up about 90% of the total surface of the gastrointestinal tract. However, adenocarcinomas arise rarely in this location. To elucidate genetic alterations underlying tumour development in the small intestine we investigated 17 sporadic adenocarcinomas. By comparative genomic hybridization recurrent gains of chromosomal material were found at chromosomes 7, 8, 13q, and 20 (5/17, each), while non-random losses were seen at 8p, 17p (4/17, each), and 18 (8/17 cases). Deletions at 5q, the location of the APC tumour suppressor gene, were seen in three cases. Microsatellite analysis with markers on chromosomal arms 1p, 5q, 8p, 17p, 18q, 19p, and 22q revealed a microsatellite instable phenotype in two cases and a high frequency of loss at 18q21-q22 (80%). Given the high incidence of 18q21-q22 deletions, we performed sequencing analysis of SMAD4, a downstream component of the TGFbeta-pathway, located at 18q21. Four tumours displayed mutations in highly conserved domains of the gene indicating disruption of TGFbeta-signalling. Our data reveal complex genetic alterations in sporadic small intestinal carcinomas. However, most tumours share deletions of 18q21-q22, which frequently target SMAD4. This indicates that disruption of TGFbeta-signalling plays a critical role in small intestinal tumorigenesis.