ABCG2 is a potential marker of tumor-initiating cells in breast cancer.

The existence of tumor-initiating cells (TICs) within solid tumors has been hypothesized to explain tumor heterogeneity and resistance to cancer therapy. In breast cancer, the expression of CD44 and CD24 and the activity of aldehyde dehydrogenase 1 (ALDH1) can be used to selectively isolate a cell population enriched in TICs. However, the ideal marker to identify TICs has not been established. The aim of this study was to evaluate the expression of novel potential markers for TIC in breast carcinoma. We prospectively analyzed the expression of CD44, CD24, ABCG2, and CXCR4, and the activity of ALDH1 by using flow cytometry in 48 invasive ductal carcinomas from locally advanced and metastatic breast cancer patients who were administered primary chemotherapy. A mammosphere assay was employed in 30 samples. The relationship among flow cytometric analyses, ABCG2 gene expression, and clinical and pathological responses to therapy was analyzed. The GSE32646 database was analyzed in silico to identify genes associated with tumors with low and high ABCG2 expression. We observed that the presence of ABCG2(+) cells within the primary tumor was the only marker to predict the formation of mammospheres in vitro (R (2) = 0.15, p = 0.029). Quantitative polymerase chain reaction (qPCR) revealed a positive correlation between ABCG2 expression and the presence of ABCG2(+) cells within the primary tumor. The expression of ABCG2 was predictive of the response to neoadjuvant chemotherapy in our experiments and in the GSE32646 dataset (p = 0.04 and p = 0.002, respectively). The in silico analysis demonstrated that ABCG2(Up) breast cancer samples have a slower cell cycle and a higher expression of membrane proteins but a greater potential for chromosomal instability, metastasis, immune evasion, and resistance to hypoxia. Such genetic characteristics are compatible with highly aggressive and resistant tumors. Our results support the hypothesis that the presence of ABCG2(+) cells in breast carcinomas is a marker of resistance to chemotherapy, and based on in vitro assays and the genetic profile, we show, for the first time, that ABCG2 protein can be used as an independent marker for TIC identification in breast cancer.

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.

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.

CD44+/CD24- cells and lymph node metastasis in stage I and II invasive ductal carcinoma of the breast.

The presence of tumor-initiating cells (CD44(+)/CD24(-)) in solid tumors has been reported as a possible cause of cancer metastasis and treatment failure. Nevertheless, little is know about the presence of CD44(+)/CD24(-) cells within the primary tumor and metastasis. The proportion of CD44(+)/CD24(-) cells was analyzed in 40 samples and in 10 lymph node metastases using flow cytometry phenotyping. Anti-human CD326 (EpCam; FITC), anti-human CD227 (MUC-1; FITC), anti-human CD44 (APC), and anti-human CD24 (PE), anti-ABCG2 (PE), and anti-CXCR4 (PeCy7) were used for phenotype analysis. The mean patient age was 60.5 years (range, 33-87 years); mean primary tumor size (pT) was 1.8 cm (0.5-3.5 cm). The Wilcoxon or Kruskal-Wallis test was used for univariate analyses. Logistic regression was used for multivariate analysis. The median percentage of CD44(+)/CD24(-) cells within primary invasive ductal carcinomas (IDC) was 2.7% (range, 0.2-71.2). In lymph node metastases, we observed a mean of 6.1% (range, 0.07-53.7). The percentage of CD44(+)/CD24(-) cells in IDCs was not associated with age, pT, tumor grade and HER2. We observed a significantly enrichment of CD44(+)/CD24(-) and ABCG2(+) cells in ESA(+) cell population in patients with positive lymph nodes (P = 0.02 and P = 0.04, respectively). Our data suggest that metastatic dissemination is associated with an increase in tumor-initiating cells in stage I and II breast cancer.

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.