Myriam Sánchez de Gómez

A non-radioactive PCR-SSCP analysis allows to distinguish between HPV 16 European and Asian-American variants in squamous cell carcinomas of the uterine cervix in Colombia

Human Papillomavirus type 16 (HPV 16) DNA is regularly found in around 50% of all cervical carcinomas. Variants of this type have been found associated with different risks for cervical cancer development. Presence of HPV 16 variants in Colombia has not been previously reported. The aims of this study were to assess the feasibility of non-radioactive PCR-SSCP (polymerase chain reaction single-strand conformation polymorphism) analysis for determination of variability of ORF of E6, variability in the enhancer sequence of the LCR, and for establishment of the distribution of HPV 16 variants in invasive squamous cell carcinoma of the uterine cervix in Colombian women. Biopsies from 59 patients at the Instituto Nacional de Cancerología (INC) in Bogotá (Colombia) were collected. HPV detection was performed using universal primers. HPV 16 variants were detected by non-radioactive single-stranded conformational polymorphism (SSCP) analysis and direct sequencing. HPV 16 was detected in 57.6% of the tumors. The European branch was identified in 88.2% of the samples with the E-G350 class being the most prevalent variant (41.1%). The Asian-American branch was identified in 8.8% of the samples. Within this group it was possible to distinguish between c and a classes. It was not possible to determine the branch in 2.9% of the cases. A nucleotide transition (G to A) at position 7521 was the most prevalent variation (80%) found in the enhancer sequence of the LCR region. Conclusion: A non-radioactive PCR-SSCP analysis allowed us to distinguish between European and Asian-American branches of HPV 16, and to distinguish among classes in squamous cell carcinomas of the uterine cervix in Colombia. This method is an excellent alternative that can be used as a screening tool for identification of HPV 16 variants.

Abstract B85: IGF‐IR gene expression as a predictive marker of ionizing radiation response for patients with locally advanced cervical cancer

In Colombia the cancer of uterine cervix is diagnosed in advanced stages and its treatment is based on the application of the radiotherapy or radiotherapy more chemotherapy. Most of studies show that the IGF‐IR expression leads to the cellular increase of resistance to radiation, that the tumor like hypoxia induces the IGF‐IR expression and selects cells that overexpressing IGF‐IR. The aim of this study was to evaluate the effect of expression of IGF‐IR, IGF‐I, IGF‐II, GAPDH, and hemoglobin concentration on tumoral response to ionizing radiation in patients with locally advanced cervical cancer. A series of 37 consecutive patients were recruited from 2002 to 2004. For each patient, a representative tumoral sample in fresh was taken at the time of diagnosis before the beginning of the treatment. In order to have a group control for the analysis of gene expression, 30 samples of normal tissue of uterine cervix from patients treated by exclusive hysterectomy were also analyzed. The mean age of the remaining 37 patients was 46 years (ranging from 33 to 70 years). All patients received exclusive pelvic external beam radiotherapy (EBRT). Treatment consisted of teletherapy using 6 to 18 MV photons with standard four field technique delivering a total dose of 45–50,4 Gy in 28 fractions (1.8 Gy per fraction, 5 consecutive days per week, overall EBRT treatment time 5 weeks). Follow‐up was scheduled at 6 weeks after completion of intracavitary brachytherapy, then every three months during the next 2 years. Complete remission was defined as no evidence of residual disease on clinical examination and radiological imaging, six weeks to three months after completion of the therapeutic sequence. Gene expression of IGF‐IR, IGF‐I, IGF‐II and GAPDH was determined by Real Time PCR and IGF‐IR protein was detected using Western Blot. Hemoglobin levels were also evaluated as a parameter of oxygenation before the beginning of ionizing radiation (Hgb>10g/dl;Hgb Citation Information: Cancer Prev Res 2010;3(1 Suppl):B85.

IL1B-CGTC haplotype is associated with colorectal cancer in admixed individuals with increased African ancestry

Single-nucleotide polymorphisms (SNPs) in cytokine genes can affect gene expression and thereby modulate inflammation and carcinogenesis. However, the data on the association between SNPs in the interleukin 1 beta gene (IL1B) and colorectal cancer (CRC) are conflicting. We found an association between a 4-SNP haplotype block of the IL1B (-3737C/-1464G/-511T/-31C) and CRC risk, and this association was exclusively observed in individuals with a higher proportion of African ancestry, such as individuals from the Coastal Colombian region (odds ratio, OR 2.06; 95% CI 1.31–3.25; p < 0.01). Moreover, a significant interaction between this CRC risk haplotype and local African ancestry dosage was identified in locus 2q14 (p = 0.03). We conclude that Colombian individuals with high African ancestry proportions at locus 2q14 harbour more IL1B-CGTC copies and are consequently at an increased risk of CRC. This haplotype has been previously found to increase the IL1B promoter activity and is the most frequent haplotype in African Americans. Despite of limitations in the number of samples and the lack of functional analysis to examine the effect of these haplotypes on CRC cell lines, our results suggest that inflammation and ethnicity play a major role in the modulation of CRC risk.

Abstract PR08: The role of genetic structure in Colombian coastal and Andean populations on disparities in colorectal adenomas and cancer risk

Background: Latin-Americans have different proportions of Amerindian, African and European genetic ancestry. Particularly, in Colombia the degree of admixture varies across the country as a result of very complex demographic events taken place since 16th century (colonization) and sex-bias gene flow effects. Colorectal cancer (CRC) mortality rates are heterogeneous across Colombian territory and this variation could be explained by regional differences in Colombian genetic background. Methods: To evaluate the association of genetic ancestry and colorectal adenomas and cancer risk, we genotyped 813 samples from Colombian coastal and andean regions, including 349 controls, 292 CRC cases and 172 adenomatous polyps (AP). Autosomal and X-chromosome individual ancestries were estimated using ADMIXTURE software with 556 AIMS (Fst > 0.5 among HAPMAP reference populations; k=3) and differences in ancestry proportions were assessed using a t-test. Multinomial logit model analysis between phenotype and ancestry proportions (covariates: sex, age, NSAIDs consumption, city of provenance and educational level) were conducted in R. Results: We found statistical differences (p Conclusions: Colombian regions have differences in the degree of admixture as a consequence of the highly asymmetric pattern of mating of European men with Native American women and the African slavery trade in the coasts since the colonization period, according to this study and others on Y-chromosome and mtDNA. There was no signal of sampling bias in our study (no differences in phenotypes by city). The association of CRC risk and African ancestry did not remain in the full model, probably due to a small effect, small sample size or the fact that people without education (low socioeconomical status) have less access to health system. The association of AP risk with European ancestry remained after controlling with covariates (including educational level); this probably indicates that there are European genetic factors (ej: SNPs) modifying the risk of AP in Colombians. Our results highlight the importance of performing Local Admixture Inference analysis in order to estimate the ancestry of specific chromosomal regions in admixed individuals in the study of human evolutionary history and genetic association studies. This abstract is also presented as Poster C37. Citation Format: Maria Carolina Sanabria-Salas, Gustavo Adolfo Hernandez-Suarez, Adriana Umana-Perez, Martha Lucia Serrano-Perez, Myriam Sanchez de Gomez, Martha Patricia Rojas, Jovanny Zabaleta, Konrad Rawlik, Albert Tenesa. The role of genetic structure in Colombian coastal and Andean populations on disparities in colorectal adenomas and cancer risk. [abstract]. In: Proceedings of the Eighth AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 13-16, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2016;25(3 Suppl):Abstract nr PR08.

OBTENCION DE UN ANTJSUERO ESPECIFICO CONTRA LA FORMA 22K DE LA HORMONA DE CRECIMIENTO HUMANA (hGH)

En el presente trabajo se describe la obtencion del anticuerpo policlonal especifico contra la fraccion monomerica 22K de la hormona de crecimiento humana (hGH). La hormona fue obtenida a partir de hipofisis humanas congeladas, mediante un esquema de extraccion basado en diferencias de solubilidad y la fraccion 22K separada por cromatografia de filtracion por gel. El antisuero especifico fue obtenido por inoculacion del antigeno en conejos raza Nueva Zelanda, cuya produccion fue controlada valorando el titulo por RIA. La caracterizacion parcial del antisuero se realizo mediante la determinacion del titulo optimo, especificidad, afinidad, y su aplicabilidad para cuantificacion en terminos de curva estandar y control de calidad, en comparacion con el antisuero de referencia. Los resultados indicaron que el antisuero puede emplearse en la cuantificacion de hGH por RIA.