Ramucirumab and paclitaxel in patients with gastric cancer and prior trastuzumab: subgroup analysis from RAINBOW study.

Aim: This subgroup analysis of the RAINBOW study evaluated the efficacy and safety of ramucirumab in patients with gastric cancer/gastroesophageal junction adenocarcinoma who received prior trastuzumab therapy. Patients & methods: Of adult patients enrolled in the RAINBOW study, 39 had received prior trastuzumab therapy. Of these, 20 patients were treated with ramucirumab plus paclitaxel and 19 patients with placebo plus paclitaxel within the RAINBOW trial. Results: Overall survival was longer with ramucirumab plus paclitaxel (11.4 months; 95% CI: 7.0-17.9) versus placebo plus paclitaxel (7.0 months; 95% CI: 3.4-14.6), hazard ratio: 0.68 (0.33-1.41); p = 0.30. Longer progression-free survival, higher objective response were observed in ramucirumab combination group. Conclusion: Ramucirumab plus paclitaxel demonstrated efficacy benefits with manageable safety profile in a subgroup of patients pretreated with trastuzumab. Clinical trial registration number: NCT01170663.

Hypotonicity induces membrane protrusions and actin remodeling via activation of small GTPases Rac and Cdc42 in Rat-1 fibroblasts.

An important consequence of cell swelling is the reorganization of the F-actin cytoskeleton in different cell types. We demonstrate in this study by means of rhodamine-phalloidin labeling and fluorescence microscopy that a drastic reorganization of F-actin occurs in swollen Rat-1 fibroblasts: stress fibers disappear and F-actin patches are formed in peripheral extensions at the cell border. Moreover, we demonstrate that activation of both Rac and Cdc42, members of the family of small Rho GTPases, forms the link between the hypotonic stimulation and F-actin reorganization. Indeed, inhibition of the small GTPases RhoA, Rac, and Cdc42 (by Clostridium difficile toxin B) prevents the hypotonicity-induced reorganization of the actin cytoskeleton, whereas inhibition of RhoA alone (by C. limosum C3 exoenzyme) does not preclude this rearrangement. Second, a direct activation and translocation toward the actin patches underneath the plasma membrane is observed for endogenous Rac and Cdc42 (but not for RhoA) during cell swelling. Finally, transfection of Rat-1 fibroblasts with constitutively active RhoA, dominant negative Rac, or dominant negative Cdc42 abolishes the swelling-induced actin reorganization. Interestingly, application of cRGD, a competitor peptide for fibronectin-integrin association, induces identical membrane protrusions and changes in the F-actin cytoskeleton that are also inhibited by C. difficile toxin B and dominant negative Rac or Cdc42. Moreover, cRGD also induces a redistribution of endogenous Rac and Cdc42 to the newly formed submembranous F-actin patches. We therefore conclude that hypotonicity and cRGD remodel the F-actin cytoskeleton in Rat-1 fibroblasts in a Rac/Cdc42-dependent way.

RhoA exerts a permissive effect on volume-regulated anion channels in vascular endothelial cells.

Cell swelling triggers in most cell types an outwardly rectifying anion current, I(Cl,swell), via volume-regulated anion channels (VRACs). We have previously demonstrated in calf pulmonary artery endothelial (CPAE) cells that inhibition of the Rho/Rho kinase/myosin light chain phosphorylation pathway reduces the swelling-dependent activation of I(Cl,swell). However, these experiments did not allow us to discriminate between a direct activator role or a permissive effect. We now show that the Rho pathway did not affect VRAC activity if this pathway was activated by transfecting CPAE cells with constitutively active isoforms of Galpha (a Rho activating heterotrimeric G protein subunit), Rho, or Rho kinase. Furthermore, biochemical and morphological analysis failed to demonstrate activation of the Rho pathway during hypotonic cell swelling. Finally, manipulating the Rho pathway with either guanosine 5'-O-(3-thiotriphosphate) or C3 exoenzyme had no effect on VRACs in caveolin-1-expressing Caco-2 cells. We conclude that the Rho pathway exerts a permissive effect on VRACs in CPAE cells, i.e., swelling-induced opening of VRACs requires a functional Rho pathway, but not an activation of the Rho pathway.