Dormant breast cancers resurge as metastatic disease after a long dormancy period in the bone marrow, where cancer cells interact with mesenchymal stem cells (MSC). However, the nature of early interactions between breast cancer cells and MSCs in the bone marrow microenvironment that facilitate adaptation to a quiescent state remains poorly understood. Here, we report that breast cancer cells prime MSC to release exosomes containing distinct miRNA contents, such as miR-222/223, which in turn promotes quiescence in a subset of cancer cells and confers drug resistance. Building on these results, we developed a novel, nontoxic therapeutic strategy to target dormant breast cancer cells based on systemic administration of MSC loaded with antagomiR-222/223. In an immunodeficient mouse model of dormant breast cancer, this therapy sensitized breast cancer cells to carboplatin-based therapy and increased host survival. Overall, our findings illuminate the nature of the regulatory interactions between breast cancer cells and MSCs in the evolution of tumor dormancy and resurgence in the micrometastatic microenvironment of the bone marrow.

Bullying is a serious problem within the U.S. school system. Prior research suggests that victimization is stratified by race and ethnicity. However, few studies consider factors that may moderate this relationship. This article extends research on this topic by considering whether stereotypes moderate bullying among racial and ethnic youth. Youth who violate stereotypes may experience derogatory treatment. This study examines whether violated racial and ethnicity stereotypes are linked to the victimization of racial and ethnic minorities. The study findings based on data from the Education Longitudinal Study of 2002 indicate that stereotypes linked to family socioeconomic status (SES), test scores, and interscholastic sports participation moderate the relationship between bullying victimization and race and ethnicity. The implications for future research and policy implementation are discussed.

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