Lung-Derived Selectins Enhance Metastatic Behavior of Triple Negative Breast Cancer Cells

The lung is one of the deadliest sites of breast cancer metastasis, particularly for triple negative breast cancer (TNBC). We have previously shown that the lung produces several soluble factors that may enhance the metastatic behavior of TNBC, including E-, L-, and P-selectin. In this paper, we hypothesize that lung-derived selectins promote TNBC metastatic behavior and may serve as a potential therapeutic target. Lungs were isolated from mice and used to generate lung-conditioned media (CM). Lung-derived selectins were immunodepleted and TNBC migration and proliferation were assessed in response to native or selectin-depleted lung-CM. A 3D ex vivo pulmonary metastasis assay (PuMA) was used to assess the metastatic progression of TNBC in the lungs of wild-type versus triple-selectin (ELP-/-) knockout mice. We observed that individual lung-derived selectins enhance in vitro migration (p ≤ 0.05), but not the proliferation of TNBC cells, and that ex vivo metastatic progression is reduced in the lungs of ELP-/- mice compared to wild-type mice (p ≤ 0.05). Treatment with the pan-selectin inhibitor bimosiamose reduced in vitro lung-specific TNBC migration and proliferation (p ≤ 0.05). Taken together, these results suggest that lung-derived selectins may present a potential therapeutic target against TNBC metastasis. Future studies are aimed at elucidating the pro-metastatic mechanisms of lung-derived selectins and developing a lung-directed therapeutic approach.

Metformin Resistant MDA-MB-468 Cells Exhibit EMT-like Phenotype and Increased Migration Capacity

Purpose: Metformin is one of the most prescribed drug for the treatment of type II diabetes. Its anti-proliferative effect is also taken advantage for the treatment of cancer. Despite many of the studies mention the positive effects of metformin in inhibiting the proliferation of cancer cells, there are also studies which questions this idea as well.Methods: In this study, we investigated the most widely studied breast cancer cell lines, ER(+) MCF7 cells, TNBC MDA-MB-231 and MDA-MB468 cells in terms of metastatic behavior under long-term metformin treatment. MCF7, MDA-MB231 and MDA-MB468 cells were gained resistant to metformin starting from 0.2mM to 3.2mM. Results: Compared to MCF7 and MDA-MB231 cell lines, we only observed dramatic changes in MDA-MB468 cells whose morphology has been changed towards mesenchymal like phenotype. Moreoever, migration capacity of these cells were also significanlty increased which were validated at both mRNA and protein levels as well as wound healing assay. In addition EMT like phenotype and increasing migration capacity of metformin resistant MDA-MB468 cells, they exhibited less sensitivity to PI3K inhibitor. Conclusions: All together, our data pointed out that, metformin’s effects should be questioned depending on the subtype of the breast cancer that’s to be treated.

When Viruses Cross Developmental Pathways

Aberrant regulation of developmental pathways plays a key role in tumorigenesis. Tumor cells differ from normal cells in their sustained proliferation, replicative immortality, resistance to cell death and growth inhibition, angiogenesis, and metastatic behavior. Often they acquire these features as a consequence of dysregulated Hedgehog, Notch, or WNT signaling pathways. Human tumor viruses affect the cancer cell hallmarks by encoding oncogenic proteins, and/or by modifying the microenvironment, as well as by conveying genomic instability to accelerate cancer development. In addition, viral immune evasion mechanisms may compromise developmental pathways to accelerate tumor growth. Viruses achieve this by influencing both coding and non-coding gene regulatory pathways. Elucidating how oncogenic viruses intersect with and modulate developmental pathways is crucial to understanding viral tumorigenesis. Many currently available antiviral therapies target viral lytic cycle replication but with low efficacy and severe side effects. A greater understanding of the cross-signaling between oncogenic viruses and developmental pathways will improve the efficacy of next-generation inhibitors and pave the way to more targeted antiviral therapies.