Abstract P4-06-06: Comparison of the immunological and clinical effect of personalized peptide vaccination for patients with breast cancer

Background: Selected therapeutic personalized peptide vaccines (PPV) were effective for boosting anticancer immune response that was associated with the clinical outcome as a prognostic factor for metastatic recurrent breast cancer (mrBC) 1-2. In this study, we investigated the immunological and clinical effect of PPV as the prophylactic cancer vaccine for non-recurrent but high-risk BC (nrhrBC) patients (pts), and we compared it's features to those of the mrBC pts who had active cancers or became resistant to the standard therapies(TR-mrBC). Methods: Material and Patient eligibility criteria: The peptides were selected from the 31 PPVs according to the results of HLA typing and peptide-specific IgG titers. Pts with a histological diagnosis of BC and their HLA-A molecules should be each of -A2, A3, A11, A24, A26, A31 or A33. The clinical protocols were approved by the institutional review board. (UMIN000003081and 00000184400000). Treatment schedule: A maximum of 4 peptides was administrated as weekly for initial four vaccinations and as biweekly for further inoculations. The concomitant standard endocrine therapy and the chemo-endocrine therapy were available for nrhrBC pts after finishing the standard adjuvant chemotherapy, and for mrBC pts concurrently. Immune and clinical response assessment: Specific T-cell responses, IgG titers and cytokines were evaluated using by interferon (IFN)-γ ELISPOT, Luminex assay and ELISA system in every 6-8 vaccinations. Toxicity, clinical response and correlation with the immune responses were investigated. Results: 16 pts with nrhrBC, 41 pts with mrBC and 79 pts with TR-mrBC received median 18, 16 and 14 vaccines, respectively. After PPV therapies, peptide-specific IgG and CTLs increased significantly in a total of 47 (77%) and 37(60%) in nrhrBC pts, 102 (63%) and 98 (61%) in mrBC pts, and 150(53%) and 100 (42%) in TR-mrBC pts. Pts experienced Grade 1-3 skin reaction at injection site, no other grade 3 or 4 SAEs were associated with PPV but with the disease progression or combination therapy. The median time to progression (TTP) and overall survival (OS) were not reached in nrhrBC pts, 7.8 and 29 months in mrBC pts, and were 7.5 and 15.9 months in TR-mrBC pts, respectively. The peptide specific CTL response was correlated significantly with OS in nrhrBC pts and the IgG levels were associated with the better OS in either non TR-mrBC pts or TR-mrBC pts. High levels of IL-6, GM-CSF, IFN-g, IL-2 receptor, BAFF were associated with worse prognosis for pts with TR-mrBC. And high levels of GM-CSF and BAFF were associated with worse prognosis for pts with nrhrBC and mrBC, respectively. In contrast, High levels of IL-2 were associated with the better prognosis for pts with mrBC. Conclusion: This study indicated that immunological features of these three groups were different from each other with most potent PPV-induced immune boosting for nrhrBC pts. Pts with mrBC who had lower immune-suppressive cytokine levels had the better prognosis. These results suggested the PPV therapy could be effective for postoperative prophylactic vaccination in patients with nrhrBC. References: 1. Takahashi R, Toh U, et al. Breast Cancer Res. 2014; 2. Toh U, Okabe M, et al. THE BREAST 2015.

Citation Format: Toh U, Okabe M, Takao Y, Tanaka Y, Shigaki T, Takenaka M, Iwakuma N, Sudo T, Yamada A, Shichijo S, Itoh K, Akagi Y. Comparison of the immunological and clinical effect of personalized peptide vaccination for patients with breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-06-06.

Plant cation/H+ exchangers (CAXs): biological functions and genetic manipulations

Inorganic cations play decisive roles in many cellular and physiological processes and are essential components of plant nutrition. Therefore, the uptake of cations and their redistribution must be precisely controlled. Vacuolar antiporters are important elements in mediating the intracellular sequestration of these cations. These antiporters are energized by the proton gradient across the vacuolar membrane and allow the rapid transport of cations into the vacuole. CAXs (for CAtion eXchanger) are members of a multigene family and appear to predominately reside on vacuoles. Defining CAX regulation and substrate specificity have been aided by utilising yeast as an experimental tool. Studies in plants suggest CAXs regulate apoplastic Ca(2+) levels in order to optimise cell wall expansion, photosynthesis, transpiration and plant productivity. CAX studies provide the basis for making designer transporters that have been used to develop nutrient enhanced crops and plants for remediating toxic soils.

The expression of the open reading frame of Arabidopsis CAX1, but not its cDNA, confers metal tolerance in yeast

The biochemical properties and regulation of several plant CAX (CAtion eXchanger)-type vacuolar Ca2+/H+ exchangers have been extensively analysed in yeast expression assays. In the present study, we compare and contrast the phenotypes of yeast cells expressing the CAX1 cDNA and open reading frame (ORF). We report that the CAX1 ORF, but not the cDNA containing the 3′-untranslated region (UTR), was able to confer Ca2+ tolerance when expressed in a Ca2+-sensitive yeast mutant. Additionally, only yeasts expressing the N-terminal truncated CAX1 ORF were able to grow on high Mn2+ media, suggesting that removal of the 3′-UTR altered activity. However, removal of the 3′-UTR from another CAX did not alter the yeast phenotypes. Expression studies demonstrated that expressing the CAX1 ORF in yeast elevates CAX1 RNA and protein levels. Our results suggest that the 3′-UTR modulates expression of CAX1 in yeast.

Identification of three distinct phylogenetic groups of CAX cation/proton antiporters

Ca(2+)/cation antiporter (CaCA) proteins are integral membrane proteins that transport Ca(2+) or other cations using the H(+) or Na(+) gradient generated by primary transporters. The CAX (for CAtion eXchanger) family is one of the five families that make up the CaCA superfamily. CAX genes have been found in bacteria, Dictyostelium, fungi, plants, and lower vertebrates, but only a small number of CAXs have been functionally characterized. In this study, we explored the diversity of CAXs and their phylogenetic relationships. The results demonstrate that there are three major types of CAXs: type I (CAXs similar to Arabidopsis thaliana CAX1, found in plants, fungi, and bacteria), type II (CAXs with a long N-terminus hydrophilic region, found in fungi, Dictyostelium, and lower vertebrates), and type III (CAXs similar to Escherichia coli ChaA, found in bacteria). Some CAXs were found to have secondary structures that are different from the canonical six transmembrane (TM) domains-acidic motif-five TM domain structure. Our phylogenetic tree indicated no evidence to support the cyanobacterial origin of plant CAXs or the classification of Arabidopsis exchangers CAX7 to CAX11. For the first time, these results clearly define the CAX exchanger family and its subtypes in phylogenetic terms. The surprising diversity of CAXs demonstrates their potential range of biochemical properties and physiologic relevance.

Diverse functions and molecular properties emerging for CAX cation/H+ exchangers in plants

Steep concentration gradients of many ions are actively maintained, with lower concentrations typically located in the cytosol, and higher concentrations in organelles and outside the cell. The vacuole is an important storage organelle for many ions. The concentration gradient of cations is established across the plant tonoplast, in part, by high-capacity cation/H+ (CAX) exchange activity. While plants may not be green yeast, analysis of CAX regulation and substrate specificity has been greatly aided by utilizing yeast as an experimental tool. The basic CAX biology in ARABIDOPSIS has immediate relevance toward understanding the functional interplay between diverse transport processes. The long-range applied goals are to identify novel transporters and express them in crop plants in order to "mine" nutrients out of the soil and into plants. In doing so, this could boost the levels of essential nutrients in plants.

Inhibition of phosphoinositide-specific phospholipase C results in the induction of pathogenesis-related genes in soybean

The inositol 1,4,5-trisphosphate (IP3) content is decreased in soybean cells following infection with Pseudomonas syringae pv. glycinea (Psg). In this investigation, a differential display approach was applied to isolate soybean genes that are transcriptionally up-regulated by the inhibition of phosphoinositide-specific phospholipase C (PI-PLC) activity and to study if the transcription of those genes is altered following Psg infection. Four genes, transcriptionally activated following treatment with the PI-PLC-specific inhibitor U-73122, were cloned. Three of the four genes were induced following infection with Psg. The transcripts of a hydrolase homologue (GmHy) were induced in the incompatible but not compatible soybean-Psg interaction. The transcripts of a putative ascorbate oxidase gene (GmAO) were induced in both compatible and incompatible interactions. GmHy and GmAO may represent new classes of pathogenesis-related genes. In addition to these two novel genes, homologues of PR-10 and polygalacturonase inhibitor protein (GmPR10 and GmPGIP, respectively) were identified. These two genes have previously been reported as pathogenesis-related. Transcripts of GmPR-10, but not GmPGIP, were induced in both compatible and incompatible soybean-Psg interactions. Induction of these genes, except for GmPGIP, following inhibition of PI-PLC by either the U-73122 treatment or bacterial infection suggests that PI-PLC may negatively regulate the expression of defence genes.

Structural determinants of Ca2+ transport in the Arabidopsis H+/Ca2+ antiporter CAX1

Ca(2+) levels in plants, fungi, and bacteria are controlled in part by H(+)/Ca(2+) exchangers; however, the relationship between primary sequence and biological activity of these transporters has not been reported. The Arabidopsis H(+)/cation exchangers, CAX1 and CAX2, were identified by their ability to suppress yeast mutants defective in vacuolar Ca(2+) transport. CAX1 has a much higher capacity for Ca(2+) transport than CAX2. An Arabidopsis thaliana homolog of CAX1, CAX3, is 77% identical (93% similar) and, when expressed in yeast, localized to the vacuole but did not suppress yeast mutants defective in vacuolar Ca(2+) transport. Chimeric constructs and site-directed mutagenesis showed that CAX3 could suppress yeast vacuolar Ca(2+) transport mutants if a nine-amino acid region of CAX1 was inserted into CAX3 (CAX3-9). Biochemical analysis in yeast showed CAX3-9 had 36% of the H(+)/Ca(2+) exchange activity as compared with CAX1; however, CAX3-9 and CAX1 appear to differ in their transport of other ions. Exchanging the nine-amino acid region of CAX1 into CAX2 doubled yeast vacuolar Ca(2+) transport but did not appear to alter the transport of other ions. This nine-amino acid region is highly variable among the plant CAX-like transporters. These findings suggest that this region is involved in CAX-mediated Ca(2+) specificity.

Characterization of CAX-like genes in plants: implications for functional diversity

Transporter-mediated Ca(2+) efflux from the cytoplasm is an important component of plant signal transduction. To elucidate the diversity and role of Ca(2+)/H(+) in controlling plant cytosolic Ca(2+) concentrations, homologs of CAX (for calcium exchanger) genes were cloned from Zea mays and Arabidopsis thaliana cDNA libraries. The A. thaliana homolog of CAX (AtHCX1) is 77% identical to CAX1 while the Z. mays homolog of CAX (ZmHCX1) is 64% identical to CAX1 in amino acid sequence. AtHCX1 transcripts appeared to be expressed in all tissues, and levels of AtHCX1 RNA increased after Ca(2+) or Na(+) treatment. When expressed in yeast mutants defective in vacuolar Ca(2+) uptake, ZmHCX1 and AtHCX1 failed to suppress the Ca(2+) sensitivity of these strains. These results imply that CAX-like genes may have functions in plant ion homeostasis that differ from those of previously characterized CAX genes.

A signal-detection experiment measuring the effect of computer-aided detection on radiologists' performance

PURPOSE

To evaluate how the specificity and sensitivity of computer-aided detection (CADe) algorithm outputs affected radiologists' diagnostic performances, the authors studied the effects of 25 simulated CADe algorithms with various sensitivities and specificities (from 60% to 100%).

METHODS

Six novice radiologists read 200 images that were produced by computer and randomly displayed on CRT, and their detection performances were evaluated with receiver operating characteristic analysis.

RESULTS

There were significant differences in performance among CADe types (p < 0.001).

DISCUSSION AND CONCLUSION

The overall accuracy of CADe outputs is the most significant factor affecting radiologists' performances in detection and interpretation of images. There is an approximately linear relationship between the sensitivity (specificity) of the CADe output and the reader's sensitivity (specificity), and the slope of reader sensitivity (specificity) as a linear function of CADe sensitivity (specificity) can be considered to be a positive number less than unity.

Decreased inositol 1,4,5-trisphosphate content in pathogen-challenged soybean cells

Phosphoinositide-specific phospholipase C (PI-PLC) has been shown to be transiently activated when plant cells were treated with elicitors. We thus investigated the activity of PI-PLC when soybean cells were infected with the bacterial pathogen Pseudomonas syringae pv. glycinea, by measuring cellular cytosolic inositol 1,4,5-trisphosphate (IP3) levels. We observed that IP3 content decreased in both compatible and incompatible interactions. In vitro phosphatase activities were similar in both water control and infected cells with slightly lower IP3 degradation observed for infected cells, indicating that the reduced IP3 content in infected cells most likely results from reduced PI-PLC activity. We hypothesize that reduced IP3 content following infection may lead to suppression of various housekeeping activities of the cells, thus diverting the cellular resources either to the synthesis of defense-related compounds against pathogens, and/or to the growth of pathogens.

Prevention of horizontal transmission of hepatitis B: efficacy of hepatitis B immunoglobulin and vaccine in an institution for the handicapped

In a Japanese institution for the handicapped with confirmed continuous outbreaks of hepatitis B virus (HBV) infection by horizontal nosocomial transmission, 29 susceptible subjects (8 institutionalized children and 21 medical staff) were injected intramuscularly with anti-human HBs immunoglobulin (HB Ig) and subcutaneously with HB vaccine. All cases acquired HBs antibody after injection of HB Ig and seropositivity for HB after the third inoculation of HB vaccine was 78.6%. No new case of HB occurred among the study population throughout the period investigated. This suggested the effectiveness of HB Ig and HB vaccine in the prevention of horizontal nosocomial transmission of HBV.

Mechanism of protein folding: I. General considerations and refolding of myoglobin

To explain the rapidity of the process of protein folding, we cite two aspects of hydrophobic interaction: its long-range nature and the specificity of pairing after the formation of secondary structures. These two factors, when incorporated with the growth-type mechanism, can determine the folding pathway of proteins. This mechanism is applied to myoglobin. Appropriate introduction of side chains of amino acid residues and the heme group attached to His 93 yield a refolded tertiary structure that is in good agreement with the native structure.

Intramolecular α-helix-β-structure-random coil transition in polypeptides

The present paper is devoted to the study of the conformational transition of polypeptides which are capable of forming alpha-helix, beta-structure and random coil conformations with the finite homogeneous chain model. The experimental results on the surfactant-induced conformational change of poly(L-lysine) can be well described by the present model assuming cooperative binding of the surfactant ions to the polypeptide side groups.