RHBDD2 overexpression promotes a chemoresistant and invasive phenotype to rectal cancer tumors via modulating UPR and focal adhesion genes.

The current standard of care for locally advanced rectal cancer (RC) is neoadjuvant radio-chemotherapy (NRC) with 5-fluorouracil (5Fu) as the main drug, followed by surgery and adjuvant chemotherapy. While a group of patients will achieve a pathological complete response, a significant percentage will not respond to the treatment. The Unfolding Protein Response (UPR) pathway is generally activated in tumors and results in resistance to radio-chemotherapy. We previously showed that RHBDD2 gene is overexpressed in the advanced stages of colorectal cancer (CRC) and that it could modulate the UPR pathway. Moreover, RHBDD2 expression is induced by 5Fu. In this study, we demonstrate that the overexpression of RHBDD2 in CACO2 cell line confers resistance to 5Fu, favors cell migration, adhesion and proliferation and has a profound impact on the expression of both, the UPR genes BiP, PERK and CHOP, and on the cell adhesion genes FAK and PXN. We also determined that RHBDD2 binds to BiP protein, the master UPR regulator. Finally, we confirmed that a high expression of RHBDD2 in RC tumors after NRC treatment is associated with the development of local or distant metastases. The collected evidence positions RHBDD2 as a promising prognostic biomarker to predict the response to neoadjuvant therapy in patients with RC.

Inhibition of the invasion and migration of renal carcinoma 786­o­si3 cells in vitro and in vivo by Koelreuteria formosana extract.

Koelreuteria formosana ethanolic extract (KFEE) is obtained from natural plants that are endemic to Taiwan. In a previous study, it was demonstrated that KFEE inhibited low-density lipoprotein (LDL) and prevented oxidized LDL­induced apoptosis in endothelial cells. In the present study, KFEE was shown to inhibit the invasion and migration of 786­O­SI3 renal cell carcinoma (RCC) cells while not exhibiting any cytotoxic effects. 786­O­SI3 cells were treated with KFEE at numerous concentrations of ≤100 µg/ml for 24 h. In order to examine the effects of KFEE, cells were then subjected to a series of assays for cell viability (MTT), wound healing migration, cell invasion and migration, gelatin zymography, casein zymography and immunofluorescence, as well as western blot analysis. KFEE was shown to decrease levels of matrix metalloproteinase­2, phosphorylated (p­)focal adhesion kinase Try925, p­paxillin Ser178, p­mitogen­activated protein kinase kinase 1/2, p­myosin light chain and p­extracellular signal-regulated kinase 1/2 in 786-0-SI3 cells. Reduction of lung metastases was observed in KFEE-treated mice compared with vehicle­treated control mice. KFEE inhibited the invasion of RCC cells and may have the potential for use as a chemopreventive agent against RCC metastasis.

NAD+ biosynthesis ameliorates a zebrafish model of muscular dystrophy.

Muscular dystrophies are common, currently incurable diseases. A subset of dystrophies result from genetic disruptions in complexes that attach muscle fibers to their surrounding extracellular matrix microenvironment. Cell-matrix adhesions are exquisite sensors of physiological conditions and mediate responses that allow cells to adapt to changing conditions. Thus, one approach towards finding targets for future therapeutic applications is to identify cell adhesion pathways that mediate these dynamic, adaptive responses in vivo. We find that nicotinamide riboside kinase 2b-mediated NAD+ biosynthesis, which functions as a small molecule agonist of muscle fiber-extracellular matrix adhesion, corrects dystrophic phenotypes in zebrafish lacking either a primary component of the dystrophin-glycoprotein complex or integrin alpha7. Exogenous NAD+ or a vitamin precursor to NAD+ reduces muscle fiber degeneration and results in significantly faster escape responses in dystrophic embryos. Overexpression of paxillin, a cell adhesion protein downstream of NAD+ in this novel cell adhesion pathway, reduces muscle degeneration in zebrafish with intact integrin receptors but does not improve motility. Activation of this pathway significantly increases organization of laminin, a major component of the extracellular matrix basement membrane. Our results indicate that the primary protective effects of NAD+ result from changes to the basement membrane, as a wild-type basement membrane is sufficient to increase resilience of dystrophic muscle fibers to damage. The surprising result that NAD+ supplementation ameliorates dystrophy in dystrophin-glycoprotein complex- or integrin alpha7-deficient zebrafish suggests the existence of an additional laminin receptor complex that anchors muscle fibers to the basement membrane. We find that integrin alpha6 participates in this pathway, but either integrin alpha7 or the dystrophin-glycoprotein complex is required in conjunction with integrin alpha6 to reduce muscle degeneration. Taken together, these results define a novel cell adhesion pathway that may have future therapeutic relevance for a broad spectrum of muscular dystrophies.