Second-line treatment with irinotecan plus cisplatin vs cisplatin of patients with advanced non-small-cell lung cancer pretreated with taxanes and gemcitabine: a multicenter randomised phase II study

The aim of this study was to compare the irinotecan/cisplatin regimen with cisplatin as second-line chemotherapy in patients with advanced non-small-cell lung cancer (NSCLC) pretreated with a taxane/gemcitabine regimen. Patients (n=147) with stage IV NSCLC pretreated with a taxane/gemcitabine regimen were randomly assigned to receive either irinotecan (110 mg m−2, day 1 and 100 mg m−2, day 8) and cisplatin (80 mg m−2, day 8) (IC; n=74) or CDDP (80 mg m−2, day 1) (C; n=73) every 3 weeks. Patients treated with IC and C had a median survival of 7.8 and 8.8 months, respectively (P=0.933). The 1-year survival rate was 34.3% for IC-treated patients and 31.7% for C-treated patients. Cox's regression analysis revealed that response to treatment (hazard ratio (HR)=2.787; 95% confidence interval (CI): 1.1578–4.922) and performance status (HR=1.865; 95% CI: 1.199–2.872) was independent prognostic factors for survival. Overall response rate was 22.5% (95% CI: 12.8–32.2%) for IC-treated patients and 7.0% (95% CI: 1.15–13.6%) for C-treated patients (P=0.012); tumour growth control (partial remission (PR)+stable disease (SD)) was observed in 26 (38%) IC and 25 (36%) C patients (P=0.878). There was no difference in terms of quality of life between the two chemotherapy arms. The incidence of febrile neutropenia, grade 3 and 4 neutropenia and grade 3 and 4 diarrhoea was significantly higher in the IC- than the C-treated patients. Other toxicities were mild. There were no treatment-related deaths in either arm. The IC regimen did not confer a survival benefit compared with C as second-line treatment of patients with advanced NSCLC pretreated with a taxane/gemcitabine regimen, despite its better efficacy in terms of response rate

The grapevine CAX-interacting protein VvCXIP4 is exported from the nucleus to activate the tonoplast Ca2+/H+ exchanger VvCAX3

Vacuolar cation/H+ exchangers (CAXs) have long been recognized as housekeeping components in cellular Ca2+ and trace metal homeostasis, being involved in a range of key cellular and physiological processes. However, the mechanisms that drive functional activation of the transporters are largely unknown. In the present study, we investigated the function of a putative grapevine CAX-interacting protein, VvCXIP4, by testing its ability to activate VvCAX3, previously characterized as a tonoplast-localized Ca2+/H+ exchanger. VvCAX3 contains an autoinhibitory domain that drives inactivation of the transporter and thus, is incapable of suppressing the Ca2+-hypersensitive phenotype of the S. cerevisiae mutant K667. In this study, the co-expression of VvCXIP4 and VvCAX3 in this strain efficiently rescued its growth defect at high Ca2+ levels. Flow cytometry experiments showed that yeast harboring both proteins effectively accumulated higher Ca2+ levels than cells expressing each of the proteins separately. Bimolecular fluorescence complementation (BiFC) assays allowed visualization of the direct interaction between the proteins in tobacco plants and in yeast, and also showed the self-interaction of VvCAX3 but not of VvCXIP4. Subcellular localization studies showed that, despite being primarily localized to the nucleus, VvCXIP4 is able to move to other cell compartments upon a Ca2+ stimulus, becoming prone to interaction with the tonoplast-localized VvCAX3. qPCR analysis showed that both genes are more expressed in grapevine stems and leaves, followed by the roots, and that the steady-state transcript levels were higher in the pulp than in the skin of grape berries. Also, both VvCXIP4 and VvCAX3 were upregulated by Ca2+ and Na+, indicating they share common regulatory mechanisms. However, VvCXIP4 was also upregulated by Li+, Cu2+ and Mn2+, and its expression increased steadily throughout grape berry development, contrary to VvCAX3, suggesting additional physiological roles for VvCXIP4, including the regulation of VvCAXs not yet functionally characterized. The main novelty of the present study was the demonstration of physical interaction between CXIP and CAX proteins from a woody plant model by BiFC assays, demonstrating the intracellular mobilization of CXIPs in response to Ca2+.This work was supported by the “Contrato-Programa” UIDB/04050/2020 funded by national funds through the FCT I.P. The work was also supported by FCT and European Funds (FEDER/ POCI/COMPETE2020) through the research projects [PTDC/BIAFBT/30341/2017; POCI-01–0145-FEDER-030341], [PTDC/BIAFBT/28165/2017; POCI-01–0145-FEDER-028165], and [SFRH/ BPD/107905/2015] to V.M.info:eu-repo/semantics/publishedVersio

The Arabidopsis cax3 mutants display altered salt tolerance, pH sensitivity and reduced plasma membrane H+-ATPase activity

Perturbing CAX1, an Arabidopsis vacuolar H+/Ca2+ antiporter, and the related vacuolar transporter CAX3, has been previously shown to cause severe growth defects; however, the specific function of CAX3 has remained elusive. Here, we describe plant phenotypes that are shared among cax1 and cax3 including an increased sensitivity to both abscisic acid (ABA) and sugar during germination, and an increased tolerance to ethylene during early seedling development. We have also identified phenotypes unique to cax3, namely salt, lithium and low pH sensitivity. We used biochemical measurements to ascribe these cax3 sensitivities to a reduction in vacuolar H+/Ca2+ transport during salt stress and decreased plasma membrane H+-ATPase activity. These findings catalog an array of CAX phenotypes and assign a specific role for CAX3 in response to salt tolerance