Characterization of cell lines derived from breast cancers and normal mammary tissues for the study of the intrinsic molecular subtypes

Five molecular subtypes (luminal A, luminal B, HER2-enriched, basal-like, and claudin-low) with clinical implications exist in breast cancer. Here, we evaluated the molecular and phenotypic relationships of (1) a large in vitro panel of human breast cancer cell lines (BCCLs), human mammary fibroblasts (HMFs), and human mammary epithelial cells (HMECs); (2) in vivo breast tumors; (3) normal breast cell subpopulations; (4) human embryonic stem cells (hESCs); and (5) bone marrow-derived mesenchymal stem cells (hMSC). First, by integrating genomic data of 337 breast tumor samples with 93 cell lines we were able to identify all the intrinsic tumor subtypes in the cell lines, except for luminal A. Secondly, we observed that the cell lines recapitulate the differentiation hierarchy detected in the normal mammary gland, with claudin-low BCCLs and HMFs cells showing a stromal phenotype, HMECs showing a mammary stem cell/bipotent progenitor phenotype, basal-like cells showing a luminal progenitor phenotype, and luminal B cell lines showing a mature luminal phenotype. Thirdly, we identified basal-like and highly migratory claudin-low subpopulations of cells within a subset of triple-negative BCCLs (SUM149PT, HCC1143, and HCC38). Interestingly, both subpopulations within SUM149PT were enriched for tumor-initiating cells, but the basal-like subpopulation grew tumors faster than the claudin-low subpopulation. Finally, claudin-low BCCLs resembled the phenotype of hMSCs, whereas hESCs cells showed an epithelial phenotype without basal or luminal differentiation. The results presented here help to improve our understanding of the wide range of breast cancer cell line models through the appropriate pairing of cell lines with relevant in vivo tumor and normal cell counterparts. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10549-013-2743-3) contains supplementary material, which is available to authorized users

Student's vocational choices and voluntary action: a 12-nation study

Previous research on student involvement suggested that business and engineering students manifest lowest rates of voluntary action. Similarly, it was thought that social science students are the most involved in voluntary action, with students of natural sciences and humanities in the middle. However, there were very few studies that empirically compared these assertions. Furthermore, these assertions were not investigated from cross-cultural perspectives. Based on a study of students in 12 countries (N = 6,570), we found that even when controlling for background variables, social science students are actually less engaged in voluntary action than other students. Engineering students are higher than expected on voluntary action while students of humanities are the most involved in voluntary action. When studying these differences in the 12 selected countries, local cultures and norms form different sets of findings that suggest that there is no universal trend in choice of academic field and voluntary action