The most characteristic change in progressive dementia of Alzheimer's type is a tissue deposit of amyloid beta/A4 protein, which is derived from its precursor protein APP (ref.2). Structural alterations of APP are implicated in the pathogenesis of Alzheimer's disease, but it is not known how they cause the disease. Although APP has a receptor-like architecture, is located on the neuronal surface, and has a conserved cytoplasmic domain, no receptor function has been demonstrated for APP. Here we report that APP forms a complex with G(o), a major GTP-binding protein in brain. The cytoplasmic APP sequence His 657-Lys 676 shows a specific G(o)-activating function and is necessary for complex formation. G(o) protein treated with GTP-gamma S lost the ability to associate with APP. This suggests that APP is a receptor coupled to G(o) and that abnormal APP-G(o) signalling is involved in the Alzheimer's disease process.

Amyloid precursor protein (APP), a transmembrane precursor of beta-amyloid, possesses a function whereby it associates with G(o) through its cytoplasmic His657-Lys676. Here we demonstrate that APP has a receptor function. In phospholipid vesicles consisting of baculovirally made APP695 and brain trimeric G(o), 22C11, a monoclonal antibody against the extracellular domain of APP, increased GTP gamma S binding and the turnover number of GTPase of G(o) without affecting its intrinsic GTPase activity. This effect of 22C11 was specific among various antibodies and was observed neither in G(o) vesicles nor in APP695/Gi2 vesicles. In APP695/G(o) vesicles, synthetic APP66-81, the epitope of 22C11, competitively antagonized the action of 22C11. Monoclonal antibody against APP657-676, the G(o) binding domain of APP695, specifically blocked 22C11-dependent activation of G(o). Therefore, APP has a potential receptor function whereby it specifically activates G(o) in a ligand-dependent and ligand-specific manner.

◥ Accumulating evidence indicates that CD8 þ T cells in the tumor microenvironment and systemic CD4 þ T-cell immunity play an important role in mediating durable antitumor responses. We longitudinally examined T-cell immunity in the peripheral blood of patients with non-small lung cancer and found that responders had significantly (P < 0.0001) higher percentages of effector, CD62L low CD4 þ T cells prior to PD-1 blockade. Conversely, the percentage of CD25 þ FOXP3 þ CD4 þ T cells was significantly (P ¼ 0.034) higher in nonresponders. We developed a formula, which demonstrated 85.7% sensitivity and 100% specificity, based on the percentages of CD62L low CD4 þ T cells and CD25 þ FOXP3 þ cells to predict nonresponders. Mass cytometry analysis revealed that the CD62L low CD4 þ T-cell subset expressed T-bet þ , CD27 À , FOXP3 À , and CXCR3 þ , indicative of a Th1 subpopulation. CD62L low CD4 þ T cells significantly correlated with effector CD8 þ T cells (P ¼ 0.0091) and with PD-1 expression on effector CD8 þ T cells (P ¼ 0.0015). Gene expression analysis revealed that CCL19, CLEC-2A, IFNA, IL7, TGFBR3, CXCR3, and HDAC9 were preferentially expressed in CD62L low CD4 þ T cells derived from responders. Notably, longterm responders, who had >500-day progression-free survival, showed significantly higher numbers of CD62L low CD4 þ T cells prior to PD-1 blockade therapy. Decreased CD62L low CD4 þ T-cell percentages after therapy resulted in acquired resistance, with longterm survivors maintaining high CD62L low CD4 þ T-cell percentages. These results pave the way for new treatment strategies for patients by monitoring CD4 þ T-cell immune statuses in their peripheral blood.

No abstract

No abstract

This study was prospectively designed to evaluate a phase II study of gefitinib for non-small-cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutations. Clinical samples were tested for EGFR mutations by peptide nucleic acid-locked nucleic acid PCR clamp, and patients having EGFR mutations were given gefitinib 250 mg daily as the second treatment after chemotherapy. Poor PS patients omitted chemotherapy. Of 107 consecutive patients enrolled, samples from 100 patients were informative, and EGFR mutations were observed in 38 patients. Gefitinib was given to 27 patients with EGFR mutations, and the response rate was 78% (one complete response and 20 partial responses; 95% confidence interval: 58 -93%). Median time to progression and median survival time (MST) from gefitinib treatment were 9.4 and 15.4 months, respectively. Grade 3 hepatic toxicity and skin toxicity were observed in one patient each. There were significant differences between EGFR mutations and wild-type patients in response rates (78 vs 14%, P ¼ 0.0017), and MST (15.4 vs 11.1 months, P ¼ 0.0135). A Cox proportional hazards model indicated that negative EGFR mutation was a secondary prognostic factor (hazards ratio: 2.259, P ¼ 0.036). This research showed the need for screening for EGFR mutations in NSCLC patients.

APP is a transmembrane precursor of beta‐amyloid. In dominantly inherited familial Alzheimer's disease (FAD), point mutations V6421, V642F and V642G have been discovered in APP695. Here we show that expression of these mutants (FAD‐APPs) causes a clone of COS cells to undergo apoptosis associated with DNA fragmentation. Apoptosis by the three FAD‐APPs was the highest among all possible V642 mutants; normal APP695 had no effect on apoptosis, suggesting that apoptosis by APP mutants in this system is phenotypically linked to the FAD trait. FAD‐APP‐induced apoptosis was sensitive to bcl‐2 and most probably mediated by heteromeric G proteins. This study presents a model system allowing analysis of the mechanism for FAD‐APP‐induced cytotoxicity.

The ⑀4 genotype of apolipoprotein E (apoE4) is the most established predisposing factor in Alzheimer's disease (AD); however, it remains unclear how apoE4 contributes to the pathophysiology. Here, we report that the apoE4 protein (ApoE4) evokes apoptosis in neuronal cells through the low-density lipoprotein receptor-related protein (LRP) and heterotrimeric GTPases. We examined neuron/neuroblastoma hybrid F11 cells and found that these cells were killed by 30 g/ml ApoE4, but not by 30 g/ml ApoE3. ApoE4-induced death occurred with typical features for apoptosis in time-and dose-dependent manners, and was observed in SH-SY5Y neuroblastomas, but not in glioblastomas or non-neuronal Chinese hamster ovary cells. Activated, but not native, ␣2-macroglobulin suppressed this ApoE4 toxicity. Suppression by the antisense oligonucleotide to LRP and inhibition by low nanomolar concentrations of LRP-associated protein RAP provided evidence for the involvement of LRP. The involvement of heterotrimeric GTPases was demonstrated by the findings that (1) ApoE4-induced death was suppressed by pertussis toxin (PTX), but not by heat-inactivated PTX; and (2) transfection with PTX-resistant mutant cDNAs of G␣ i restored the toxicity of ApoE4 restricted by PTX. We thus conclude that one of the neurotoxic mechanisms triggered by ApoE4 is to activate a cell type-specific apoptogenic program involving LRP and the G i class of GTPases and that the apoE4 gene may play a direct role in the pathogenesis of AD and other forms of dementia.