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Background: PD-L1 intrinsically promotes tumor progression through multiple mechanisms, which potentially leads to resistance to anti-PD-1/PD-L1 therapies. The intrinsic effect of PD-L1 on breast cancer (BC) cell proliferation has not been fully elucidated. Methods: we used proteomics, gene expression knockdown (KD), quantitative immunofluorescence (qIF), western blots, functional assays including colony-forming assay (CFA) and real-time cell analyzer (RTCA), and in vivo data using immunohistochemistry in breast cancer patients. Results: PD-L1 promoted BC cell proliferation by accelerating cell cycle entry at the G1-to-S phase transition. Global proteomic analysis of the differentially expressed nuclear proteins indicated the involvement of several proliferation-related molecules, including p21CIP1/WAF1. Western blotting and qIF demonstrated the higher expression of SKP2 and the lower expression of p21CIP1/WAF1 and p27Kip1 in PD-L1 expressing (PD-L1pos) cells as compared to PD-L1 KD (PD-L1KD) cells. Xenograft-derived cells and the TCGA BC dataset confirmed this relationship in vivo. Functionally, CFA and RTCA demonstrated the central role of SKP2 in promoting PD-L1-mediated proliferation. Finally, immunohistochemistry in 74 breast cancer patients confirmed PD-L1 and SKP-p21/p27 axis relationship, as it showed a highly statistically significant correlation between SKP2 and PD-L1 expression (p < 0.001), and both correlated significantly with the proliferation marker Ki-67 (p < 0.001). On the other hand, there was a statistically significant inverse relationship between PD-L1 and p21CIP1/WAF1 expression (p = 0.005). Importantly, double negativity for p21CIP1/WAF1 and p27Kip1 correlated significantly with PD-L1 (p < 0.001), SKP2 (p = 0.002), and Ki-67 (p = 0.002). Conclusions: we have demonstrated the role of the SKP2-p27/p21 axis in intrinsic PD-L1-enhanced cell cycle progression. Inhibitors of SKP2 expression can alleviate resistance to ICPIs. [ABSTRACT FROM AUTHOR]

Background BRCA1 promoter methylation has been detected in DNA from peripheral blood cells of both breast cancer patients and cancer-free females. However, the pathological significance of this epigenetic change in white blood cells (WBC) remains an open question. In this study, we hypothesized that if constitutional BRCA1 methylation reflects an elevated risk for developing breast cancer (BC), WBC that harbor methylated BRCA1 in both cancer-free females and BC patients should exhibit similar molecular changes. Methods BRCA1 promoter methylation was examined by methylation-specific PCR in WBC from 155 breast cancer patients and 143 cancer-free females. Furthermore, The Human Breast Cancer EpiTect Methyl II Signature PCR Array and The Human Breast Cancer RT² Profiler™ PCR Array were used to study the methylation status and the expression profile of several breast cancer-related genes, respectively. In addition, we used label-free MS-based technique to study protein expression in plasma. Results We have shown that 14.2% of BC patients and 9.1% of cancer-free females (carriers) harbored methylated BRCA1 promoter in their WBC. Interestingly, 66.7% of patients harbored methylated BRCA1 promoter in both WBC and tumors. Importantly, we have shown the presence of epigenetic changes in 9 other BC-related genes in WBC of both patients and carriers. Additionally, BRCA1 and 15 other important cancer-related genes were found to be differentially expressed in WBC from patients and carriers as compared to controls. Furthermore, we have shown that the carriers exhibited a unique plasma protein pattern different from those of BC patients and controls, with 10 proteins similarly differentially expressed in patients and carriers as compared to controls. Conclusions The present results suggest the presence of a strong link between aberrant methylation of the BRCA1 promoter in WBC and breast cancer-related molecular changes, which indicate the potential predisposition of the carriers for developing breast cancer. This informs the potential use of the aberrant methylation of BRCA1 promoter in WBC as a powerful non-invasive molecular marker for detecting predisposed individuals at a very early age. [ABSTRACT FROM AUTHOR]

Background: There are a number of dietary components that may prove useful in the prevention and treatment of cancer. In some cultures, fenugreek seeds are used to treat cancer. The current study focuses on the anticancer properties and proteomic profiles of fenugreek seeds, and is prompted by the clinical profile of a case of primary CNS T cell lymphoma that responded to fenugreek treatment and resulted in tumor regression. Method: Various normal and cancer cell lines were exposed to fenugreek extract at differing concentrations (100 µg/ml, 200 µg/ml and 300 µg/ml) and at different time points (0, 24, 48, 72 and 96 hrs). Protein fingerprints of fenugreek grain/seed types, obtained from four different geographical regions, were analyzed by proteomic expression profiles. Results: We observed selective cytotoxic effects of fenugreek extract in vitro to a panel of cancer cell lines, including T-cell lymphoma. Additionally, the cluster analysis of proteomics data showed that the protein profile of the particular fenugreek used by the patient is significantly different from three other regional subtypes of fenugreek extract. Conclusion: The in vitro effect of fenugreek as a substance with significant cytotoxicity to cancer cells points to the potential usefulness of fenugreek in the prevention and treatment of cancer. [ABSTRACT FROM AUTHOR]

Background Mesenchymal stem cells have properties that make them amenable to therapeutic use. However, the acceptance of mesenchymal stem cells in clinical practice requires standardized techniques for their specific isolation. To date, there are no conclusive marker (s) for the exclusive isolation of mesenchymal stem cells. Our aim was to identify markers differentially expressed between mesenchymal stem cell and non-stem cell mesenchymal cell cultures. We compared and contrasted the phenotype of tissue cultures in which mesenchymal stem cells are rich and rare. By initially assessing mesenchymal stem cell differentiation, we established that bone marrow and breast adipose cultures are rich in mesenchymal stem cells while, in our hands, foreskin fibroblast and olfactory tissue cultures contain rare mesenchymal stem cells. In particular, olfactory tissue cells represent non-stem cell mesenchymal cells. Subsequently, the phenotype of the tissue cultures were thoroughly assessed using immunofluorescence, flow-cytometry, proteomics, antibody arrays and qPCR. Results Our analysis revealed that all tissue cultures, regardless of differentiation potential, demonstrated remarkably similar phenotypes. Importantly, it was also observed that common mesenchymal stem cell markers, and fibroblast-associated markers, do not discriminate between mesenchymal stem cell and non-stem cell mesenchymal cell cultures. Examination and comparison of the phenotypes of mesenchymal stem cell and non-stem cell mesenchymal cell cultures revealed three differentially expressed markers - CD24, CD108 and CD40. Conclusion We indicate the importance of establishing differential marker expression between mesenchymal stem cells and non-stem cell mesenchymal cells in order to determine stem cell specific markers. [ABSTRACT FROM AUTHOR]