Analysis of gene expression EGFR and KRAS, microRNA-21 and microRNA-203 in patients with colon and rectal cancer and correlation with clinical outcome and prognostic factors

Abstract Purpose: To evaluate the expression of EGFR, KRAS genes, microRNAs-21 and 203 in colon and rectal cancer samples, correlated with their age at diagnosis, histological subtype, value of pretreatment CEA, TNM staging and clinical outcome. Methods: Expression of genes and microRNAs by real time PCR in tumor and non-tumor samples obtained from surgical treatment of 50 patients. Results: An increased expression of microRNAs-21 and 203 in tumor samples in relation to non-tumor samples was found. There was no statistically significant difference between the expression of these genes and microRNAs when compared to age at diagnosis and histological subtype. The EGFR gene showed higher expression in relation to the value of CEA diagnosis. The expression of microRNA-203 was progressively lower in relation to the TNM staging and was higher in the patient group in clinical remission. Conclusions: The therapy of colon and rectum tumors based on microRNAs remains under investigation reserving huge potential for future applications and clinical interventions in conjunction with existing therapies. We expect, based on the exposed data, to stimulate the development of new therapeutic possibilities, making the treatment of these tumors more effective.

Marcadores e mecanismos de resistência à terapia neoadjuvante e o papel das vesículas extracelulares secretadas pelas células tumorais no câncer de reto / Biomarkers and mechanisms of resistance to neoadjuvnat therapy and the role of extracelular vesicles secreted by tumor cells in rectal cancer

O câncer de reto é o segundo tumor mais comum no intestino grosso correspondendo a um terço do total de casos de câncer colorretal (CCR). Pacientes com câncer de reto em estádios II e III são tratados com radioquimioterapia neoadjuvante seguida de ressecção cirúrgica do tumor. Análises das peças cirúrgicas ressecadas mostraram que apenas 10-45% dos pacientes obtém resposta patológica completa (RCp) à terapia neoadjuvante, estando essa associada com uma diminuição da recorrência local, melhora da sobrevida livre de doença e aumento na preservação esfincteriana. Apesar da melhora na sobrevida nas últimas décadas, a resposta à terapia neoadjuvante continua variável e imprevisível e não é possível identificar e separar clinicamente os grupos de pacientes que terão ou não resposta completa ao tratamento neoadjuvante. Além disso, os mecanismos de resistência à radioquimioterapia nos tumores de reto são pouco compreendidos. Dessa forma, o objetivo principal deste estudo foi identificar marcadores e mecanismos celulares relacionados à resistência à terapia neoadjuvante em adenocarcinoma de reto e o papel das vesículas extracelulares (VEs) nesse processo. O estudo proteômico comparativo entre biópsias obtidas de tumores pré-tratamento com o tumor residual removido cirurgicamente pós-tratamento radioquimioterápico mostrou uma importante alteração no perfil de expressão proteica. Entre as proteínas que aumentam a expressão após a neoadjuvância estão as proteínas de reparo de dano de DNA, Ku70 e Ku80, e a proteína de tráfego intracelular Rab5C. Em um modelo in vitro, foi demonstrado que Rab5C orquestra um mecanismo de resistência à radioterapia nos tumores de reto através da modulação da internalização de EGFR promovida por radiação ionizante (RI). O EGRF intracelular por sua vez é essencial para regular a expressão de Ku70 e Ku80 e a resistência celular à RI. Estes dados apontam Rab5C e EGFR como potenciais alvos terapêuticos para sensibilizar células de câncer de reto resistentes ao tratamento neoadjuvante. Também foi observado que a RI promove alterações epigenéticas predominantemente de hipometilação, e entre os genes alterados estão SPG20 e TBC1D16, sendo o primeiro importante para a internalização de EGFR e o segundo para a regulação de Rab5C e modulação de EGFR. O perfil de expressão proteica foi ainda comparado entre biópsias pré-tratamento de pacientes com RCp e sem resposta patológica, e o resultado mostrou que esses dois grupos de pacientes apresentam um diferente perfil de expressão proteica. Nos pacientes com RCp as proteínas com aumento da expressão estão atuando em vias que favorecem a resposta à terapia, como a detoxificação de glutationa e degradação de glicogênio, enquanto as proteínas com aumento da expressão em pacientes sem RCp estão envolvidas em vias do metabolismo energético do tumor as quais contribuem para a resistência tumoral à terapia. As diferenças observadas nestes grupos devem ser amplamente exploradas uma vez que podem ser marcadores preditivos de resposta ao tratamento radioquimioterápico. A realização de estudos funcionais foi viabilizada pela geração de um modelo celular de tumor de reto resistente à radioterapia. Ao analisar as VEs secretadas por estas células foi observado que a RI não altera a quantidade e o tamanho médio das VEs secretadas, porém é capaz de alterar o carregamento proteico das mesmas. De fato, as VEs de células irradiadas apresentam um perfil proteico diferente quando comparadas as VEs de células não irradiadas, onde encontramos aumento da expressão de Ku70, Ku80 e Rab5C, além das metiltransferases NSUN2 e GLYM nas VEs de células pós RI. Interessantemente, as VEs secretadas por células irradiadas são capazes de transmitir a resistência à RI às células não irradiadas. Além disso os resultados mostraram que o tratamento com VEs de células irradiadas promove metilação em 98% do DNA avaliado em células SW837 em comparação ao tratamento com VEs de células não irradiadas. Os genes hipermetilados estão envolvidos em vias relacionadas ao sistema imune, como a apresentação de antígeno, sinalização de imunodeficiência primária e maturação de células dendríticas. Por fim, foi identificado que a expressão da proteína A33 está relacionada ao grau de diferenciação dos tumores colorretais, e que essa proteína está presente em VEs secretadas por células de adenocarcinoma de reto, indicando que a mesma pode ser usada para isolar VEs específicas do tecido colorretal. Os dados obtidos neste trabalho apontam mecanismos relacionados à resistência à terapia neoadjuvante no adenocarcinoma de reto e que em conjunto permitirão identificar novos alvos terapêuticos com potencial de melhorar a resposta à radioquimioterapia, além de identificar marcadores de resposta à terapia neoadjuvante antes do tratamento e dessa forma, poupar os pacientes não respondedores de terapias tóxicas e melhorar a sustentabilidade na saúde poupando os custos com drogas não eficientes para um grupo de pacientes.

Rectal cancer is the second most common cancer in large intestine, corresponding to one third of total cases of colorectal cancer (CRC). Patients with rectal cancer in stage II and III are treated with neoadjuvant chemoradiation followed by surgical resection. Analyzes of the resected tumor demonstrated that only 10-45% of the patients achieve pathological complete response (pCR) after neoadjuvant therapy, which is associated with a decrease in local recurrence, improvement of disease free survival and increase in sphincter preservation. Despite the improvement in survival in the last decades, the response to neoadjuvant therapy is still variable and unpredictable, and before the surgery it is not possible to identify and separate clinically the group of patients that will or will not have complete response to neoadjuvant treatment. Moreover, the mechanisms of resistance of rectal tumors to chemoradiation are poorly understood. Thus, the main objective of this work was to identify biomarkers and cellular mechanisms related to the resistance to neoadjuvant therapy in rectal adenocarcinomas and the role of extracellular vesicles (EVs) in this process. The comparative proteomic study between biopsy obtained from tumors pretreatment with residual tumor, post chemoradiation treatment, removed by surgery showed an important alteration in the protein expression profile. Among the proteins with increased expression after neoadjuvant therapy are the DNA repair proteins Ku70 and Ku80, and the protein involved in the intracellular trafficking, Rab5C. It was demonstrated in vitro that Rab5C orchestrates a mechanism of radioresistance in rectal tumors by modulating the EGFR internalization promoted by ionizing radiation (IR). The intracellular EGFR is essential to regulate Ku70 and Ku80 expression and the cell resistance to IR. These data pointed Rab5C and EGFR as potential therapeutic targets to sensitize rectal cancer cells resistant to neoadjuvant treatment. It was also observed that IR promotes epigenetic alterations, predominantly hypomethylation, and between the altered genes are SPG20 and TBC1D16, the first is important to EGFR internalization, while the second regulates Rab5C and modulates EGFR. The protein expression profile was further compared between biopsy pretreatment of patients with and without pCR, and the results showed that these two groups of patients present a different protein expression profile. In patients with pCR the proteins with increased expression are involved in pathways favoring the response to therapy, as glutathione-mediated detoxification and glycogen degradation, while the proteins with increased expression in patients without pCR are involved in tumor energetic metabolism pathways that contribute to tumor resistance to therapy. The observed differences in these groups should be widely explored since they may be predictive markers of response to chemoradiation treatment. The performance of functional studies was possible by generation of a cellular model of rectal tumor resistant to radiotherapy. The analysis of the EVs secreted by these cells showed that IR does not alter the amount and the medium size of secreted EVs, but is able to change their protein content. EVs from irradiated cells presented a different protein profile when compared to EVs from non-irradiated cells, where it was found the increased expression of Ku70, Ku80 and Rab5C, besides the methyltransferases NSUN2 and GLYM in EVs after irradiation. Interestingly, the EVs secreted by irradiated cells are capable of transfering resistance to IR to non-irradiated cells. Moreover, the results showed that the treatment of SW837 cells with EVs from irradiated cells promoted methylation in 98% of the analyzed DNA in comparison with the treatment with EVs from non-irradiated cells. The hypermethylated genes are involved in pathways related to immune system, as antigen presentation, primary immunodeficiency signaling and dendritic cells maturation. Lastly, it was identified that the A33 expression is related to the colorectal tumors differentiation degree, and this protein is present in EVs secreted by rectal adenocarcinoma, indicating that it may be used to isolate EVs specific from colorectal tissues. The data obtained in this work pointed to mechanisms related to resistance to neoadjuvant therapy in rectal adenocarcinoma that together will allow to identify new therapeutic targets with the potential to improve the response to chemoradiation, as well as to identify markers of response to neoadjuvant therapy before the treatment, and, in this way, avoid the non-responder patients to receive toxic therapies and improve health sustainability, sparing cost with non-efficient drugs for a group of patients.

Carga de doença no Brasil: um olhar sobre o álcool e a cirrose não viral / Disease burden in Brazil: an investigation into alcohol and non-viral cirrhosis

O uso/dependência de álcool é importante fator de risco para o desenvolvimento da cirrose. O objetivo deste artigo é descrever e analisar o DALY (Disability Adjusted Life Years), o YLL (Years of Life Lost) e o YLD (Years Lived with Disability) de uso/dependência de álcool e da cirrose de etiologia não viral no Brasil, em 2008. O DALY foi calculado pela soma do YLL e do YLD. Para o YLL, foi utilizada a média dos óbitos de 2007-2009 no país. Através da revisão de dados epidemiológicos e do uso da ferramenta DisMod, a prevalência de cada um dos agravos foi modelada, gerando dados de incidência para o cálculo do YLD. O álcool e a cirrose foram responsáveis, respectivamente, por 3% e 1% do DALY total. Considerando-se as dez primeiras causas de DALY para homens, o uso/ dependência de álcool ocupou a segunda, terceira e sexta posições nas idades de 15-29, 30-44 e 45-59 anos, respectivamente. A cirrose ocupou a oitava posição no grupo de 30-44 anos; a quinta, no de 45-59 e a oitava, no de 60-69. A distribuição dos agravos por faixa etária sugere que intervenções direcionadas ao uso/dependência de álcool terão efeitos na carga de cirrose alcoólica no país.

Alcohol use/dependence are an important risk factor for cirrhosis of the liver. The article aims to describe and conduct a comparative analysis of Disability Adjusted Life Years (DALY), Years of Life Lost (YLL) and Years Lived with Disability (YLD) of alcohol use disorders and non-viral cirrhosis in Brazil in 2008. DALY was calculated as the sum of YLL and YLD. For YLL estimates, the mean number of deaths from 2007- 2009 in the country was considered. After revision of epidemiological data, prevalence of each disease was modelled with the DisMod tool, which generated incidence data for YLD estimates. Alcohol and non-viral cirrhosis were responsible for 3% and 1% of total DALYs, respectively. In both diseases, men contributed to a greater proportion of DALYs. Among the first ten causes of DALYs, alcohol use disorders occupied the second, third and sixth positions at the ages of 15-29, 30-44 and 45- 59, respectively. Non-viral cirrhosis was the eighth cause of DALY in the 30-44 age group in men; the fifth, in the 45-59 group and the eighth, in the 60-69 group. Age distribution suggests that interventions directed against alcohol use/dependence would have effects on the burden of alcoholic cirrhosis in the country.

Polimorfismo genético de interleuquina-1: Asociación con cáncer gástrico en la población de alto riesgo del Centroccidente de Venezuela / lnterleukin-1 genetic polymorphism: Association with gastric cancer in the high-risk Central-Western population of Venezuela

Background: Genetic predisposition may play a role in the prevalence of gastric cancer (GC). Aim: To investigate the relationship between selected interleukin-1 (IL-1) loci polymorphisms and gastric cancer risk in the Central-Western region of Venezuela, where gastric cancer represents the first cause of cancer-related deaths. Material and methods: In a case-control study, we compared the frequencies of IL-1B-511 and IL-1B+3954 biallelic polymorphism, and the pentallelic VNTR of IL-IRN in 84 gastric adenocarcinoma paraffin-embedded biopsies and 84 endoscopic biopsies from cancer-free controls. Results: No significant increase in genotypic frequencies in gastric cancer was observed for any of the IL-1B-511 allelic combinations. However, in alogistic regression analysis, a significant association emerged for the IL- 1B+3954C carrier genotype (odds ratio (OR): 6.2; 95% confidence intervals (CI) 1.3-28.8). On the other hand, a significantly higher risk was evidenced for the IL-IRN*2/*2 genotype (OR: 7.0; 95% CI 2.3-21.5). Only patients with awell/moderately-differentiated adenocarcinoma that were homozygotes for the IL-IRN*2/*2 genotype, had a higher risk than the complete gastric cancer group (OR: 8.1, 95% CI 2.5-26.8). Some genotype combinations among IL-1B-511, IL-1B+3954 and IL-IRN showed an increased risk for developing gastric cancer and well/moderate differentiated adenocarcinoma, that was dependent of the presence of IL-IRN*2/*2 genotype. Conclusions: IL-IRN*2/*2 genotype is associated with increased risk of gastriccancer in the Venezuelan population.

Association between polymorphisms of the androgen and vitamin D receptor genes with prostate cancer risk in a Mexican population / Asociación entre polimorfismo de andrógenos y receptores de vitamina D con riesgo de cáncer prostático en una población mexicana

Introduction. Prostate cancer (PCa) is a worldwide health issue, because of its high incidence and mortality. Its etiology is complex and includes certain risk factors such as age, hormonal status, ethnic origin and family history of PCa. Genetic predisposition is proposed as a major risk factor and there are several controversial reports on the association of PCa and gene polymorphism such as the receptors of the androgen receptor (AR) and the vitamin D (VDR). Objective. To evaluate the CAG triplets repetitions in the first exon of the AR and polymorphisms in the restriction site Taql in the VDR in Mexicans with PCa. Material and methods. A total of 68 Mexicans with histopathological diagnosis of PCa and 48 healthy Mexican with normal prostate specific antigen and rectal exam where included. 10ml of peripheral blood were extracted to isolate DNA and the polymorphisms were evaluated with specific primers for the AR and VDR. Results. The allelic and genetic distributions of the AR and VDR polymorphisms were consistent with the Hardy-Weinberg equilibrium, and there were no statistical differences between the PCa patients and controls (p > 0.05). However, there was a statistical difference between the number of CAG repeats in younger patients with PCa compared to controls (p = 0.045) but when the young patient group was compared versus the elder group there was not stadistically difference (p = 0.085), but the results showed a tendency towards less repetitions of CAG in elder patients. Concerning the VDR, when we analyzed the patients with PCa and a bad pathological prognosis they had a less frequent genotype of TT (p = 0.03). Conclusions. Our results suggest an association between the VDR and AR gene polymorphisms, and the hystopathological score and age at diagnosis in Mexican patients with PCa, respectively. However, it is important to confirm these results in a larger scale study.

Introducción. El cáncer de próstata (PCa) es un problema de salud mundial, tanto por su elevada incidencia como mortalidad. Su etiología es compleja e incluye factores de riesgo reconocidos como la edad, estado hormonal, origen étnico y antecedentes familiares de PCa. El fondo genético es un factor de riesgo y existen reportes controversiales de la asociación de PCa y polimorfismos en los genes como son los receptores de vitamina D (VDR) y el de andrógenos (AR). Objetivo. Evaluar las repeticiones de tripletes de CAG en el primer exon del AR y polimorfismos en el sitio de restricción Taql en el VDR en mexicanos con PCa. Material y métodos. Se incluyeron 68 mexicanos con diagnóstico histopatológico de PCa y 48 mexicanos con niveles normales de antígeno prostático y tacto rectal normal. Se les extrajo 10 mL de sangre periférica para aislar DNA y mediante olígos específicos se evaluaron los polimorfismos mencionados. Resultados. La distribución alélica y genotípica de los polimorfismos en el AR y VDR fueron consistentes con el equilibrio de Hardy-Weinberg, y no mostraron diferencias significativas entre los casos y controles (p > 0.05). Sin embargo, el número de repeticiones de CAG en el AR fueron estadísticamente diferentes en pacientes jóvenes con PCa comparados con los controles (p = 0.045), cuando se comparó el grupo de pacientes de jóvenes contra aquellos mayores de 60 años no se encontró diferencia estadísticamente significativa (p - 0.085); sin embargo, se observó una tendencia de un número menor de repetidos CAG en pacientes mayores con PCa. Por otra parte, al comparar VDR en los pacientes con PCa de mal pronóstico por el patrón histológico tenían menor frecuencia de genotipos TT (p - 0.03). Conclusiones. Nuestros resultados sugieren una asociación entre los polimorfismos de los genes del VDR y AR, y el patrón histológico y la edad al diagnóstico en pacientes mexicanos con PCa, respectivamente. Sin embargo, es necesario confirmar estos resultados en un estudio con mayor número de pacientes.

Estudio endoscópico en familiares de primer grado de pacientes operados por cáncer colorrectal / Screening colonoscopy among first degree relatives of patients with colorectal carcinoma

Background: First degree relatives of patients with colorectal carcinoma are at a higher risk of having the disease than the general population. Therefore, they should be subjected to screening colonoscopy. Aim: To assess the effectiveness of colonoscopy among first degree relatives of patients with colorectal carcinoma. Material and methods: A free colonoscopy was offered to first degree relatives of patients operated on for colorectal cancer between 1998 and 2000. As inclusion criteria, subjects had to be asymptomatic, older than 40 years or less than 10 years younger than the index case. Each subject was contacted twice, inviting him/her to have a colonoscopy performed. Results: Two hundred forty three relatives were contacted for the study and in 76, a colonoscopy was performed. Among the latter, a neoplasm was found in 13 (17 percent): One adenocarcinoma and 12 adenomas. Three of these lesions were located in the right colon. The main reason given by the 176 subjects that did not agree to have a colonoscopy was lack of interest. Conclusions: Screening colonoscopy is effective to detect adenoma and adenocarcinomaamong first degree relatives of patients with colorectal carcinoma, however only 31 percent of all potential relatives agreed to undergo a colonoscopy.