Tissue-Associated Bacterial Alterations in Rectal Carcinoma Patients Revealed by 16S rRNA Community Profiling.

Sporadic and inflammatory forms of colorectal cancer (CRC) account for more than 80% of cases. Recent publications have shown mechanistic evidence for the involvement of gut bacteria in the development of both CRC-forms. Whereas, colon and rectal cancer have been routinely studied together as CRC, increasing evidence show these to be distinct diseases. Also, the common use of fecal samples to study microbial communities may reflect disease state but possibly not the tumor microenvironment. We performed this study to evaluate differences in bacterial communities found in tissue samples of 18 rectal-cancer subjects when compared to 18 non-cancer controls. Samples were collected during exploratory colonoscopy (non-cancer group) or during surgery for tumor excision (rectal-cancer group). High throughput 16S rRNA amplicon sequencing of the V4-V5 region was conducted on the Ion PGM platform, reads were filtered using Qiime and clustered using UPARSE. We observed significant increases in species richness and diversity in rectal cancer samples, evidenced by the total number of OTUs and the Shannon and Simpson indexes. Enterotyping analysis divided our cohort into two groups, with the majority of rectal cancer samples clustering into one enterotype, characterized by a greater abundance of Bacteroides and Dorea. At the phylum level, rectal-cancer samples had increased abundance of candidate phylum OD1 (also known as Parcubacteria) whilst non-cancer samples had increased abundance of Planctomycetes. At the genera level, rectal-cancer samples had higher abundances of Bacteroides, Phascolarctobacterium, Parabacteroides, Desulfovibrio, and Odoribacter whereas non-cancer samples had higher abundances of Pseudomonas, Escherichia, Acinetobacter, Lactobacillus, and Bacillus. Two Bacteroides fragilis OTUs were more abundant among rectal-cancer patients seen through 16S rRNA amplicon sequencing, whose presence was confirmed by immunohistochemistry and enrichment verified by digital droplet PCR. Our findings point to increased bacterial richness and diversity in rectal cancer, along with several differences in microbial community composition. Our work is the first to present evidence for a possible role of bacteria such as B. fragilis and the phylum Parcubacteria in rectal cancer, emphasizing the need to study tissue-associated bacteria and specific regions of the gastrointestinal tract in order to better understand the possible links between the microbiota and rectal cancer.

Assessment of staging, prognosis and mortality of colorectal cancer by tumor markers: receptor erbB-2 and cadherins

OBJETIVO: Avaliação da expressão tumoral das proteínas c-erbB-2 e E-caderina e sua relação com o prognóstico, estadiamento e grau de diferenciação celular, em doentes com câncer colo-retal . MÉTODOS: O estudo incluiu 117 doentes com média de idade de 63.1 anos e com acompanhamento médio de 28.1 meses. O intervalo livre de doença, sobrevida, índice de recidiva e mortalidade específica foram os parâmetros avaliados. Anticorpos anti-oncoproteína c-erbB-2 (Dako) foram utilizados pela técnica da estreptavidiva-biotina. Considerou-se como positiva a presença desta proteína quando mais de 10% das células tumorais estivessem coradas. A proteína E-caderina foi estudada pelo anticorpo anti-E-caderina (Dako), sendo computada como positiva a amostra que apresentasse 50% ou mais das células coradas. A análise estatística utilizou o teste do qui-quadrado de Pearson, o teste exato de Fischer, a curva de Kaplan-Meier, o teste de log-rank e o teste de Wilcoxon ( variante de Breslow),sendo estabelecido nível de significância de 5%( p<0,05). RESULTADOS: 52 de 108 doentes estudados para c-erbB-2 foram positivos (48,1%), 47 de 93 doentes estudados para E-caderina foram negativos (50,5%). Estes dados não mostraram relação com estadiamento TNM (tumor, nódulo e metástase), com o grau de diferenciação celular e índice de recidiva tumoral. O intervalo livre de doença para os doentes positivos para c-erbB-2 e negativos para E-caderina foi de 68.0 meses e não diferiu daqueles que foram negativos para c-erbB-2 e positivos para E-caderina ( 55.0 meses - p = 0.5510). A sobrevida média para os doentes positivos para c-erbB-2 e negativos para E-caderina foi 75 meses sem diferença estatisticamente significante com o outro grupo de comparação( 61 meses - p = 0.5256). A mortalidade específica foi de 20.0% dos casos e não se correlacionou com a expressão do c-erbB-2 (p=0,446) ou da E-caderina(p=0,883). CONCLUSÃO: A expressão das proteínas c-erbB-2 e E-caderina em doentes portadores de adenocarcinoma colo-retal não apresentou correlação com o estadiamento e grau de diferenciação celular. Não houve da mesma forma relação com o prognóstico, no que diz respeito ao índice de recidiva da doença, intervalo livre de doença, sobrevida e mortalidade específica.

Assessment of staging, prognosis and mortality of colorectal cancer by tumor markers: receptor erbB-2 and cadherins.

PURPOSE: To evaluate the prognostic significance and correlation with staging and degree of cell differentiation of the tumoral expression of the proteins c-erbB-2 and E-cadherin, in patients with colorectal adenocarcinoma. METHODS: The study included 117 patients with an average age of 63.1 years and an average follow-up duration of 28.1 months. The disease-free interval, survival, incidence of recurrence and specific mortality were evaluated. c-erbB-2 anti-oncoprotein antibodies (Dako) were utilized via the streptavidin-biotin technique. Samples were considered to be positive for c-erbB-2 if 10% or more of the tumor cell membranes were stained. The anti-E-cadherin antibodies (Dako), evaluated this protein and is considered positive, if 50% or more of the cell membranes were stained. Statistical analysis was performed using Pearson's chi-squared test, Fisher's exact test, Kaplan-Meier's estimator, the log-rank test and Wilcoxon's test (Breslow version), setting the level of statistical significance at 5% (p<0.05). RESULTS: 52 of 108 patients studied for c-erbB-2 were positive (48.1%), 47 of 93 patients studied for E-cadherin were negative (50.5%). These data do not express any correlation with TNM (tumor, node and metastasis) staging and the degree of cell differentiation or with the tumor recurrence rate. The disease-free interval among patients who were positive for c-erbB-2 and negative for E-cadherin was 68.0 months and did not differ from those with c-erbB-2 negative and E-cadherin positive (55.0 months--p = 0.5510). The average survival among patients positive for c-erbB-2 and negative for E-cadherin was 75 months without statistical significance difference with the other group (61 months--p = 0.5256). Specific mortality occurred in 20.0% of the cases and did not correlate with the expression of c-erbB-2 (p=0.446), E-cadherin (p=0.883). CONCLUSION: The tumoral expression of c-erbB-2 and E-cadherin did not demonstrate a correlation with the staging and degree of cell differentiation, and it did not present prognostic value regarding disease recurrence, disease-free interval, survival and specific mortality among patients with colorectal adenocarcinoma.