Breast cancer is the most diagnosed cancer worldwide and remains the second leading cause of cancer death. While breast cancer mortality has steadily declined over the past decades through medical advances, an alarming disparity in breast cancer mortality has emerged between African American women (AAW) and Caucasian American women (CAW). New evidence suggests more aggressive behavior of triple-negative breast cancer (TNBC) in AAW may contribute to racial differences in tumor biology and mortality. Progesterone (PRG) can exert its cellular effects through either its classic, non-classic, or combined responses through binding to either classic nuclear PRG receptors (nPRs) or non-classic membrane PRG receptors (mPRs), warranting both pathways equally important in PRG-mediated signaling. In our previous report, we demonstrated that the CCM signaling complex (CSC) consisting of CCM1, CCM2, and CCM3 can couple both nPRs and mPRs signaling cascades to form a CSC-mPRs-PRG-nPRs (CmPn) signaling network in nPR positive(+) breast cancer cells. In this report, we furthered our research by establishing the CSC-mPRs-PRG (CmP) signaling network in nPR(-) breast cancer cells, demonstrating that a common core mechanism exists, regardless of nPR(+⁣/⁣-) status. This is the first report stating that inducible expression patterns exist between CCMs and major mPRs in TNBC cells. Furthermore, we firstly show mPRs in TNBC cells are localized in the nucleus and participate in nucleocytoplasmic shuttling in a coordinately synchronized fashion with CCMs under steroid actions, following the same cellular distribution as other well-defined steroid hormone receptors. Finally, for the first time, we deconvoluted the CmP signalosome by using systems biology and TNBC clinical data, which helped us understand key factors within the CmP network and identify 6 specific biomarkers with potential clinical applications associated with AAW-TNBC tumorigenesis. These novel biomarkers could have immediate clinical implications to dramatically improve health disparities among AAW-TNBCs.

Background Breast cancer, the most diagnosed cancer, remains the second leading cause of cancer death in the United States, and excessive Progesterone (PRG) or Mifepristone (MIF) exposure may be at an increased risk for developing breast cancer. PRG exerts its cellular responses through signaling cascades involving classic, non-classic, or combined responses by binding to either classic nuclear PRG receptors (nPRs) or non-classic membrane PRG receptors (mPRs). Currently, the intricate balance and switch mechanisms between these two signaling cascades remain elusive. Three genes, CCM1-3, form the CCM signaling complex (CSC) which mediates multiple signaling cascades. Methods Utilizing molecular, cellular, Omics, and systems biology approaches, we analyzed the relationship among the CSC, PRG, and nPRs/mPRs during breast cancer tumorigenesis. Results We discovered that the CSC plays an essential role in coupling both classic and non-classic PRG signaling pathways by mediating crosstalk between them, forming the CmPn (CSC-mPRs-PRG-nPRs) signaling network. We found that mPR-specific PRG actions (PRG + MIF) play an essential role in this CmPn network during breast cancer tumorigenesis. Additionally, we have identified 4 categories of candidate biomarkers (9 intrinsic, 2 PRG-inducible, 1 PRG-repressive, 1 mPR-specific PRG-repressive, and 2 mPR-responsive) for Luminal-A breast cancers during tumorigenesis and have confirmed the prognostic application of RPL13 and RPL38 as intrinsic biomarkers using a dual validation method. Conclusions We have discovered that the CSC plays an essential role in the CmPn signaling network for Luminal-A breast cancers with identification of two intrinsic biomarkers.

In the present study, we have established Dextertype long-term cultures (D-LTC) from human umbilical cord blood (UCB) and followed the kinetics of different hematopoietic progenitor cells (HPCs)-including multipotent (colony forming unit [CFU]-Mixture), erythroid (CFU-erythroid, BFU-E), and myeloid (CFU-granulocyte, CFU-macrophage, CFU-granulocyte/macrophage) progenitors as well as of morphologically recognizable erythroid, myeloid and lymphoid cells-during a nineweek culture period. D-LTC were also established from adult bone marrow (BM) as controls. On day 0, both UCB and BM showed similar total numbers of HPCs (about 310/10 5 cells), however, UCB showed a higher proportion of primitive HPCs (i.e., CFU-Mixture, CFUgranulocyte/macrophage and BFU-E). A poor adherent cell layer, consisting almost exclusively of macrophages, was developed in UCB D-LTC and this correlated with a continuous decline in HPC numbers throughout the culture period. In contrast, adherent cell numbers in BM D-LTC, including fibroblasts and macrophages, were two-to fourfold higher than in UCB cultures, and the numbers of HPCs were also significantly higher, reaching plateau levels between weeks 6 and 9. In both types of cultures, erythroid and multipotent progenitors declined relatively fast, reaching undetectable levels after five weeks of culture. Myeloid progenitors, on the other hand, were sustained longer (always at higher levels in BM cultures) and were still detected by week 9. Among myeloid progenitors, a shift towards the predominance of macrophage HPCs was observed, both in UCB and BM D-LTC, and this correlated with an increase in the proportion of mature monocytes and macrophages. Taken together, our results indicate that myeloid progenitor cell growth is deficient in UCB D-LTC and suggest that this is due to the impaired development of an adherent cell layer, unable to provide the factors and conditions required for their growth. Interestingly, throughout the culture period the total numbers of multipotent and erythroid progenitors were similar both in UCB and BM cultures regardless of the number and types of adherent cells present; this suggests that the stroma developed in D-LTC is not sufficient for the proliferation of these progenitor cells.

No abstract

Breast cancer is the most commonly diagnosed cancer worldwide and remains the second leading cause of cancer death. While breast cancer mortality has steadily declined over the past decades through medical advances, an alarming disparity in breast cancer mortality has emerged between African American women (AAW) and Caucasian American women (CAW); and new evidence suggests more aggressive behavior of triple-negative breast cancer (TNBC) in AAW may contribute to racial differences in tumor biology and mortality. Progesterone (PRG) is capable of exerting its cellular effects through either its classic, non-classic or combined responses through binding to either classic nuclear PRG receptors (nPRs) or non-classic membrane PRG receptors (mPRs), warranting both pathways an equally important status in PRG-mediated signaling. In our previous report, we demonstrated that the CCM signaling complex (CSC) consisting of CCM1, CCM2, and CCM3 proteins can couple both nPRs and mPRs signaling cascades to form a CSC-mPRs-PRG-nPRs (CmPn) signaling network in nPR positive(+) breast cancer cells. In this report, we furthered our research by establishing the CSC-mPRs-PRG (CmP) signaling network in nPR(-) breast cancer cells, demonstrating that a common core mechanism exists, regardless of nPR(+/-) cell type. This is the first report stating that inducible expression patterns exist between CCMs and major mPRs in TNBC cells. Furthermore, we firstly show mPRs in TNBC cells are localized in the nucleus and participate in nucleocytoplasmic shuttling in a coordinately synchronized fashion with CCM proteins under steroid actions, following the same cellular distribution as other well-defined steroid hormone receptors. Finally, for the first time, we deconvoluted the CmP signalosome by using multi-omics approaches, which helped us understand key factors within the CmP network, and identify 21 specific biomarkers with potential clinical applications associated with AAW-TNBC tumorigenesis. These novel biomarkers could have immediate clinical implications to dramatically improve health disparities among AAW-TNBCs.