Multigene assays highlight racial disparities in tumor subtype distribution that persist even in clinically defined subgroups. Differences in tumor biology (eg, HER2-enriched status) may be targetable to reduce disparities among clinically ER+/HER2- cases.

Effective antiretroviral (ARV)-based HIV prevention strategies require optimizing drug exposure in mucosal tissues; yet factors influencing mucosal tissue disposition remain unknown. We hypothesized drug transporter expression in vaginal, cervical, and colorectal tissues is a contributing factor and selected three efflux (ABCB1/MDR1, ABCC2/MRP2, ABCC4/MRP4) and three uptake (SLC22A6/OAT1, SLC22A8/OAT3, SLCO1B1/OATP1B1) transporters to further investigate based on their affinity for 2 ARVs central to prevention (tenofovir, maraviroc). Tissue was collected from 98 donors. mRNA and protein expression were quantified using qPCR and immunohistochemistry (IHC). 100% of tissues expressed efflux transporter mRNA. IHC localized them to the epithelium and/or submucosa. Multivariable analysis adjusted for age, smoking, and co-medications revealed significant (p<0.05) differences in efflux transporter mRNA between tissue types (vaginal ABCB1 3.9 fold > colorectal; vaginal ABCC2 2.9 fold>colorectal; colorectal ABCC4 2.0 fold>cervical). In contrast, uptake transporter mRNA was expressed in <25% of tissues. OAT1 protein was detected in 0% of female genital tissues and in 100% of colorectal tissues, but only in rare epithelial cells. These data support clinical findings of higher maraviroc and tenofovir concentrations in rectal tissue compared to vaginal or cervical tissue after oral dosing. Quantifying mucosal transporter expression and localization can facilitate antiretroviral selection to target these tissues.

Breast cancers with lactating features, some of which are associated with pregnancy and lactation, are often poorly differentiated, lack estrogen receptor, progesterone receptor, and HER2 expression and have high mortality. Very little is known about the molecular mechanisms that drive uncontrolled cell proliferation in these tumors and confer lactating features. We have recently reported expression of OCT4 and associated embryonic stem cell self-renewal genes in the normal lactating breast and breastmilk stem cells (hBSCs). This prompted us to examine OCT4 expression in breast cancers with lactating features and compare it with that observed during normal lactation, using rare specimens of human lactating breast. In accordance with previous literature, the normal resting breast (from non-pregnant, non-lactating women) showed minimal OCT4 nuclear expression (0.9%). However, this increased in the normal lactating breast (11.4%), with further increase in lactating adenomas, lactating carcinomas, and pregnancy-associated breast cancer (30.7–48.3%). OCT4 was expressed in the epithelium and at lower levels in the stroma, and was co-localized with NANOG. Comparison of normal non-tumorigenic hBSCs with OCT4-overexpressing tumorigenic breast cell lines (OTBCs) demonstrated upregulation of OCT4, SOX2, and NANOG in both systems, but OTBCs expressed OCT4 at significantly higher levels than SOX2 and NANOG. Similar to hBSCs, OTBCs displayed multi-lineage differentiation potential, including the ability to differentiate into functional lactocytes synthesizing milk proteins both in vitro and in vivo. Based on these findings, we propose a hypothesis of normal and malignant transformation in the breast, which centers on OCT4 and its associated gene network. Although minimal expression of these embryonic genes can be seen in the breast in its resting state throughout life, a controlled program of upregulation of this gene network may be a potential regulator of the normal remodeling of the breast toward a milk-secretory organ during pregnancy and lactation. Deregulation of this gene network either within or outside pregnancy and lactation may lead to aberrant breast cell proliferation and malignant transformation, suggesting a role of these genes in both normal lactation and breast oncogenesis.

HIV replication within tissues may increase in response to a reduced exposure to antiretroviral drugs. Traditional approaches to measuring drug concentrations in tissues are unable to characterize a heterogeneous drug distribution. Here, we used mass spectrometry imaging (MSI) to visualize the distribution of six HIV antiretroviral drugs in gut tissue sections from three species (two strains of humanized mice, macaques, and humans). We measured drug concentrations in proximity to CD3+ T cells that are targeted by HIV, as well as expression of HIV or SHIV RNA and expression of the MDR1 drug efflux transporter in gut tissue from HIV-infected humanized mice, SHIV-infected macaques, and HIV-infected humans treated with combination antiretroviral drug therapy. Serial 10-μm sections of snap-frozen ileal and rectal tissue were analyzed by MSI for CD3+ T cells and MDR1 efflux transporter expression by immunofluorescence and immunohistochemistry, respectively. The tissue slices were analyzed for HIV/SHIV RNA expression by in situ hybridization and for antiretroviral drug concentrations by liquid chromatography–mass spectrometry. The gastrointestinal tissue distribution of the six drugs was heterogeneous. Fifty percent to 60% of CD3+ T cells did not colocalize with detectable drug concentrations in the gut tissue. In all three species, up to 90% of HIV/SHIV RNA was found to be expressed in gut tissue with no exposure to drug. These data suggest that there may be gut regions with little to no exposure to antiretroviral drugs, which may result in low-level HIV replication contributing to HIV persistence.

Objectives Drug transporters affect ART tissue disposition, but quantitative measures of drug transporter protein expression across pre-clinical species are not available. Our objective was to use proteomics to obtain absolute transporter concentrations and assess agreement with corresponding gene and immunometric protein data. Design In order to make interspecies comparisons, two humanized mouse (hu-HSC-Rag (n=41); BLT (n=13)) and one primate (rhesus macaque, (NHP, n=12)) models were dosed to steady-state with combination ART. Ileum and rectum were collected at necropsy and snap frozen for analysis. Methods Tissues were analyzed for gene (qPCR) and protein (LC-MS proteomics and Western blot) expression and localization (immunohistochemistry) of ART efflux and uptake transporters. Drug concentrations were measured by LC-MS/MS. Multivariable regression was used to determine the ability of transporter data to predict tissue ART penetration. Results Analytical methods did not agree, with different trends observed for gene and protein expression. For example, qPCR analysis showed a 2-fold increase in permeability glycoprotein (Pgp) expression in NHPs versus mice, however proteomics showed a 200-fold difference in the opposite direction. Proteomics results were supported by IHC staining showing extensive efflux transporter localization on the luminal surface of these tissues. ART tissue concentration was variable between species, and multivariable regression showed poor predictive power of transporter data. Conclusions Lack of agreement between analytical techniques suggests that resources should be focused on generating downstream measures of protein expression to predict drug exposure. Taken together, these data inform the use of pre-clinical models for studying ART distribution and the design of targeted therapies for HIV eradication.