Extracellular cleavage and shedding of P-cadherin: a mechanism underlying the invasive behaviour of breast cancer cells

Cell-cell adhesion is an elementary process in normal epithelial cellular architecture. Several studies have shown the role mediated by cadherins in this process, besides their role in the maintenance of cell polarity, differentiation and cell growth. However, during tumour progression, these molecules are frequently altered. In breast cancer, tumours that overexpress P-cadherin usually present a high histological grade, show decreased cell polarity and are associated with worse patient survival. However, little is known about how this protein dictates the very aggressive behaviour of these tumours. To achieve this goal, we set up two breast cancer cell models, where P-cadherin expression was differently modulated and analysed in terms of cell invasion, motility and migration. We show that P-cadherin overexpression, in breast cancer cells with wild-type E-cadherin, promotes cell invasion, motility and migration. Moreover, we found that the overexpression of P-cadherin induces the secretion of matrix metalloproteases, specifically MMP-1 and MMP-2, which then lead to P-cadherin ectodomain cleavage. Further, we showed that soluble P-cadherin fragment is able to induce in vitro invasion of breast cancer cells. Overall, our results contribute to elucidate the mechanism underlying the invasive behaviour of P-cadherin expressing breast tumours.scientific project (POCI/BIA-BCM/59252/2004) financed by the Portuguese Science and Technology Foundation (FCT). FCT also provided research grants as follows: Programa Ciência 2007 (FCT) for Joana Paredes, and PhD research grants for Ana Sofia Ribeiro (SFRH/BD/36096/2007) and André Albergaria (SFRH/BD/15316/2005)

Radiosensitization of renal cell carcinoma in vitro through the induction of autophagy.

BACKGROUND AND PURPOSE: For patients diagnosed with advanced renal cell carcinoma (RCC), there are few therapeutic options. Radiation therapy is predominantly used to treat metastasis and has not proven effective in the adjuvant setting for renal cancer. Furthermore, RCC is resistant to standard cytotoxic chemotherapies. Targeted anti-angiogenics are the standard of care for RCC but are not curative. Newer agents, such as mTOR inhibitors and others that induce autophagy, have shown great promise for treating RCC. Here, we investigate the potential use of the small molecule STF-62247 to modulate radiation. MATERIALS AND METHODS: Using RCC cell lines, we evaluate sensitivity to radiation in addition to agents that induce autophagic cell death by clonogenic survival assays. Furthermore, these were also tested under physiological oxygen levels. RESULTS: STF-62247 specifically induces autophagic cell death in cells that have lost VHL, an essential mutation in the development of RCC. Treatment with STF-62247 did not alter cell cycle progression but when combined with radiation increased cell killing under oxic and hypoxic/physiological conditions. CONCLUSIONS: This study highlights the possibility of combining targeted therapeutics such as STF-62247 or temsirolimus with radiation to reduce the reliance on partial or full nephrectomy and improve patient prognosis