Divalent cations modulate alpha2beta1 integrin-mediated malignancy in a novel 3-dimensional in vitro model of pancreatic cancer

Mechanically stressed cancer microenvironment: Role in pancreatic cancer progression

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal solid malignancies in the world due to its insensitivity to current therapies and its propensity to metastases from the primary tumor mass. This is largely attributed to its complex microenvironment composed of unique stromal cell populations and extracellular matrix (ECM). The recruitment and activation of these cell populations cause an increase in deposition of ECM components, which highly influences the behavior of malignant cells through disrupted forms of signaling. As PDAC progresses from premalignant lesion to invasive carcinoma, this dynamic landscape shields the mass from immune defenses and cytotoxic intervention. This microenvironment influences an invasive cell phenotype through altered forms of mechanical signaling, capable of enacting biochemical changes within cells through activated mechanotransduction pathways. The effects of altered mechanical cues on malignant cell mechanotransduction have long remained enigmatic, particularly in PDAC, whose microenvironment significantly changes over time. A more complete and thorough understanding of PDAC's physical surroundings (microenvironment), mechanosensing proteins, and mechanical properties may help in identifying novel mechanisms that influence disease progression, and thus, provide new potential therapeutic targets.

Metal ions and the extracellular matrix in tumor migration

In this review, we explore the roles of divalent metal ions in structure and function within the extracellular matrix (ECM), specifically, their interaction with glycosaminoglycans (GAGs) during tumor progression. Metals and GAGs have been individually associated with physiological and pathological processes, however, their combined activities in regulating cell behavior and ECM remodeling have not been fully explored to date. During tumor progression, divalent metals and GAGs participate in central processes, such as cell migration and angiogenesis, either by modulating cell surface molecules, as well as soluble signaling factors. In addition, studies on metals and polysaccharides interactions have been of great value, as they provide structural information that can be correlated with function. Finally, we believe that understanding how metals are regulated in physiological and pathological conditions is paramount for the development of new treatment strategies, as well as diagnostic and exploratory tools.

A 3D matrix platform for the rapid generation of therapeutic anti-human carcinoma monoclonal antibodies

Efforts to develop unbiased screens for identifying novel function-blocking monoclonal antibodies (mAbs) in human carcinomatous states have been hampered by the limited ability to design in vitro models that recapitulate tumor cell behavior in vivo. Given that only invasive carcinoma cells gain permanent access to type I collagen-rich interstitial tissues, an experimental platform was established in which human breast cancer cells were embedded in 3D aldimine cross-linked collagen matrices and used as an immunogen to generate mAb libraries. In turn, cancer-cell-reactive antibodies were screened for their ability to block carcinoma cell proliferation within collagen hydrogels that mimic the in vivo environment. As a proof of principle, a single function-blocking mAb out of 15 identified was selected for further analysis and found to be capable of halting carcinoma cell proliferation, inducing apoptosis, and exerting global changes in gene expression in vitro. The ability of this mAb to block carcinoma cell proliferation and metastatic activity was confirmed in vivo, and the target antigen was identified by mass spectroscopy as the α2 subunit of the α2β1 integrin, one of the major type I collagen-binding receptors in mammalian cells. Validating the ability of the in vitro model to predict patterns of antigen expression in the disease setting, immunohistochemical analyses of tissues from patients with breast cancer verified markedly increased expression of the α2 subunit in vivo. These results not only highlight the utility of this discovery platform for rapidly selecting and characterizing function-blocking, anticancer mAbs in an unbiased fashion, but also identify α2β1 as a potential target in human carcinomatous states.