Phenotypic switch in blood: effects of pro-inflammatory cytokines on breast cancer cell aggregation and adhesion

Towards a molecular basis of oligometastatic disease: potential role of micro-RNAs

Oligometastasis is a cancer disease state characterized by a limited number of metastatic tumors involving single or few organs and with biological properties that make them potentially amenable to locoregional antitumor therapy. Current clinical data show that they are potentially curable with surgical resection or/and radiotherapy. Yet, mechanisms of progression from primary tumor to oligometastasis, rather than to polymetastases, is lacking in detail. In the current review we focus on the role of micro-RNAs in the regulation of metastases development and the role they may play in the differentiation of oligometastatic from polymetastatic progression. We also discuss the analyses of metastatic samples from oligo-and polymetastatic patients, which suggest that oligometastasis is a distinct biologic entity regulated in part by micro-RNAs. In addition, a review of the known functions of oligometastatic-specific micro-RNAs suggest that they regulate multiple steps in the metastatic cascade, including epithelial–mesenchymal transition, tumor invasion, intravasation, distant vascular extravasation and proliferation in a distant organ. Understanding the role of micro-RNAs and their target genes in oligometastatic disease may allow for the development of targeted therapies to effectively conrol the spread of metastases.

Quantitative fluorescent profiling of VEGFRs reveals tumor cell and endothelial cell heterogeneity in breast cancer xenografts

Plasma membrane-localized vascular endothelial growth factor receptors (VEGFR) play a critical role in transducing VEGF signaling toward pro and antiangiogenic outcomes and quantitative characterization of these receptors is critical toward identifying biomarkers for antiangiogenic therapies, understanding mechanisms of action of antiangiogenic drugs, and advancing predictive computational models. While in vitro analysis of cell surface-VEGFRs has been performed, little is known about the levels of cell surface-VEGFR on tumor cells. Therefore, we inoculate nude mice with the human triple-negative breast cancer, MDA-MB-231, cell line; isolate human tumor cells and mouse tumor endothelial cells from xenografts; and quantitatively characterize the VEGFR localization on these cells. We observe 15,000 surface-VEGFR1/tumor endothelial cell versus 8200 surface-VEGFR1/tumor endothelial cell at 3 and 6 weeks of tumor growth, respectively; and we quantify 1200-1700 surface-VEGFR2/tumor endothelial cell. The tumor cell levels of VEGFR1 and VEGFR2 are relatively constant between 3 and 6 weeks: 2000-2200 surface-VEGFR1/tumor cell and ~1000 surface-VEGFR2/tumor cell. Cell-by-cell analysis provides additional insight into tumor heterogeneity by identifying four cellular subpopulations based on size and levels of cell membrane-localized VEGFR. Furthermore, when these ex vivo data are compared to in vitro data, we observe little to no VEGFRs on MDA-MB-231 cells, and the MDA-MB-231 VEGFR surface levels are not regulated by a saturating dose of VEGF. Overall, the quantification of these dissimilarities for the first time in tumor provides insight into the balance of modulatory (VEGFR1) and proangiogenic (VEGFR2) receptors.

Structural pathways of cytokines may illuminate their roles in regulation of cancer development and immunotherapy

Cytokines are messengers between tissues and the immune system. They play essential roles in cancer initiation, promotion, metastasis, and immunotherapy. Structural pathways of cytokine signaling which contain their interactions can help understand their action in the tumor microenvironment. Here, our aim is to provide an overview of the role of cytokines in tumor development from a structural perspective. Atomic details of protein-protein interactions can help in understanding how an upstream signal is transduced; how higher-order oligomerization modes of proteins can influence their function; how mutations, inhibitors or antagonists can change cellular consequences; why the same protein can lead to distinct outcomes, and which alternative parallel pathways can take over. They also help to design drugs/inhibitors against proteins de novo or by mimicking natural antagonists as in the case of interferon-γ. Since the structural database (PDB) is limited, structural pathways are largely built from a series of predicted binary protein-protein interactions. Below, to illustrate how protein-protein interactions can help illuminate roles played by cytokines, we model some cytokine interaction complexes exploiting a powerful algorithm (PRotein Interactions by Structural Matching-PRISM).

The administration of milk fermented by the probiotic Lactobacillus casei CRL 431 exerts an immunomodulatory effect against a breast tumour in a mouse model

Antitumour activity is one of the health-promoting effects attributed to probiotics specially analysed from preclinical models, mostly murine. Here, the effect of milk fermented by the probiotic bacterium Lactobacillus casei CRL 431, on a murine breast cancer model was analysed. Mice were fed with milk fermented by Lactobacillus casei or unfermented milk before and after tumour injection. Rate of tumour development, cytokines in serum, IgA, CD4, CD8, F4/80 and cytokines positive cells in mammary glands were determined. Microvasculature in the tumour tissues was monitored. The effect of fermented milk administration after tumour injection was also evaluated. It was observed that probiotic administration delayed or blocked tumour development. This effect was associated to modulation of the immune response triggered by the tumour. The area occupied by blood vessels decreased in the tumours from mice given fermented milk which agrees with their small tumours, and fewer side effects. Finally, it was observed that probiotic administration after tumour detection was also beneficial to delay the tumour growth. In conclusion, we showed in this study the potential of milk fermented by the probiotic Lactobacillus casei CRL431 to stimulate the immune response against this breast tumour, avoiding or delaying its growth when it was preventively administrated and also when the administration started after tumour cells injection.

Integrating physical sciences perspectives in cancer research

Cancer research integrated a physical sciences perspective through team science, which fostered communication, trust, joint publication, and open access to data.

Sweeping lymph node micrometastases off their feet: an engineered model to evaluate natural killer cell mediated therapeutic intervention of circulating tumor cells that disseminate to the lymph nodes

Approximately 90% of cancer related deaths are due to metastasis. Cells from the primary tumor can metastasize through either the vascular or lymphatic circulation. Cancer cells in circulation are called circulating tumor cells (CTCs) and it has been shown that bone marrow is a niche for homing of blood borne CTCs from several epithelial tumors. Cancer cells found in bone marrow are termed disseminated tumor cells (DTCs). Likewise, CTCs in the lymphatic circulation are more often seeded in the sentinel lymph nodes (SLN) that drain the tumor. Micrometastases (<2 mm) occur after the arrest and implantation of DTCs in lymph nodes over time. This paper presents a cell culture platform termed microbubbles formed in polydimethylsiloxane (PDMS) from a microfabricated silicon wafer for mimicking lymph node micrometastases. We cultured lymph node seeking cancer cells in microbubbles to evaluate the efficacy of natural killer (NK) mediated therapy for targeting lymph node micrometastasis. The microbubble platform consists of an array of microcavities that provides a unique microenvironment for mimicking the deep cortical unit of the lymph nodes. We show that cancer cells cultured in microbubbles with therapeutic NK cells undergo apoptosis after 24 h in culture. Since lymph node metastases are prevalent across several types of cancer, this platform may be useful for developing improved cancer therapies for targeting lymph node micrometastases.

Dynamic Switch Between Two Adhesion Phenotypes in Colorectal Cancer Cells

The hematogenous metastatic cascade is mediated by the interaction of cancer cells and the endothelial cell lining of blood vessels. In this work, we examine the colon cancer cell line COLO 205, which grows simultaneously in both adherent and suspended states in culture and can serve as a good model for studying tumor heterogeneity. The two subpopulations of cells have different molecular characteristics despite being from the same parent cell line. We found that the ratio of adherent to suspended cells in culture is maintained at 7:3 (equilibrium ratio). The ratio was maintained even when we separate the two populations and culture them separately. After 8 h in culture the equilibrium was achieved only from either adherent or suspended population. The adherent cells were found to express less E-selectin binding glycans and demonstrated significantly weaker interaction with E-selectin under flow than the suspended cells. Manipulation of the epithelial–mesenchymal transition (EMT) markers β-catenin and E-cadherin expression, either by siRNA knockdown of β-catenin or incubation with E-cadherin antibody-coated microbeads, shifted the ratio of adherent to suspended cells to 9:1. Interestingly, human plasma supplemented media shifted the ratio of adherent to suspended cells in the opposite direction to 1:9, favoring the suspended state. The dynamic COLO 205 population switch presents unique differential phenotypes of their subpopulations and could serve as a good model for studying cell heterogeneity and the EMT process in vitro.

Physical biology in cancer. 1. Cellular physics of cancer metastasis

One of the major challenges in cancer research today is developing new therapeutic strategies to control metastatic disease, the spread of cancer cells from a primary tumor to seed in a distant site. Advances in diagnosis and treatment options have increased the survival rate for most patients with local tumors; however, less progress has been made in treatment of disseminated disease. According to the SEER Cancer Statistics Review, 1975-2010, in the case of breast and prostate cancers, only one in four patients diagnosed with distant metastatic disease will survive more than five years. Current research efforts largely focus on identifying biological targets, such as specific genes and signaling pathways that drive two key steps of metastasis, invasion from the primary tumor and growth in the secondary site. On the other hand, there are phenotypic traits and dynamics in the metastatic process that are not encoded by single genes or signaling pathways but, rather, a larger system of events and biophysical characteristics. Connecting genomic and pathway investigations with quantitative physical phenotypic characteristics of cells, the physical microenvironment, and the physical spatiotemporal interactions of the metastatic process provides a stronger complementary understanding of the disease.