Abstract P2-05-03: Clinical implication of APOBEC3A and 3B in Korean patients with breast cancer

Background: Apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like (APOBEC) family is known to function in innate immune system that protects against retrovirus by deaminating cytosine to uracil in single-stranded DNA. APOBEC family has emerged as an endogenous mutator to contribute to the mutation burden in many cancers. We aimed to evaluate the expression of APOBEC3A (A3A), 3B (A3B) mRNA and APOBEC3A-3B deletion polymorphism in Korean breast cancer patients and investigate the correlation between their expression and clinicopathological characteristics.

Methods: One hundred thirty-eight patients who underwent surgery for breast cancer in Uijeongbu St. Mary's Hospital between January 2013 and December 2016 were evaluated. RNA and DNA were extracted from 138 breast cancer tissues and 10 adjacent normal breast tissues. The levels of A3A and A3B mRNA transcripts were determined using real-time quantitative PCR. Insertion and deletion PCR assays were performed to detect the APOBEC3A-3B deletion allele. Mutation hotspots in exon 2-11 of TP53 and exon 9/20 of PIK3CA were evaluated using direct sequencing method.

Results: The expression of A3B was increased in breast cancer tissues than in normal breast tissues. The median A3B mRNA expression levels in both triple-negative breast cancer and human epidermal growth factor 2-positive breast cancer were significantly higher than in hormone receptor-positive breast cancer. Old age and high ki-67 expression were associated with increased expression of A3A and A3B. Advanced stage, presence of lymph node involvement, and high histological grade were associated with increased expression of A3A. The APOBEC3B deletion allele was found in 78 (56%) tumor samples. There was no significant association between A3A, A3B mRNA levels and the presence of APOBEC3B deletion allele. There was no difference in clinicopathological characteristics according to the presence of APOBEC3B deletion allele except histological grade. The frequency of high histological grade was significantly higher in tumors with APOBEC3B deletion allele than tumors without APOBEC3B deletion allele. TP53 mutations were identified in 12 (8.7%) cases and PIK3CA mutations were identified in 31 (22.5%) cases. There were no significant differences in the levels of A3A and A3B mRNA expression by TP53 mutation status. The presence of a PIK3CA mutation was significantly associated with lower A3A expression.

Conclusions: The levels of A3B mRNA expression showed a difference according to breast cancer subtype, and triple-negative breast cancer showed the highest levels of A3B mRNA expression. The high levels of A3A and A3B mRNA expression were associated with an aggressive phenotype including high proliferation index. The APOBEC3A-3B deletion polymorphism was found in about half of the patients, but there was no difference in clinicopathological factors according to the presence of APOBEC3B deletion allele except histological grade.

Citation Format: Won HS, Sun DS, Ko YH, You SH, Kim YS, Kim JS. Clinical implication of APOBEC3A and 3B in Korean 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 P2-05-03.

Correction to: CDK5 Regulates PD-L1 Expression and Cell Maturation in Dendritic Cells of CRSwNP

The article CDK5 Regulates PD-L1 Expression and Cell Maturation in Dendritic Cells of CRSwNP, written by C. C. Liu, H. L. Zhang, L. L. Zhi, P. Jin, L. Zhao, T. Li, X. M. Zhou, D. S. Sun, G. H. Cheng, Q. Xin, L. Shi, and M. Xia was originally published electronically on the publisher's internet.

Immune imbalance of global gene expression, and cytokine, chemokine and selectin levels in the brains of offspring with social deficits via maternal immune activation

The murine maternal immune activation (MIA) offspring model enables longitudinal studies to explore aberrant social behaviors similar to those observed in humans. High levels of cytokines, chemokines and cell adhesion molecules (CAM) have been found in the plasma and/or brains of psychiatric patients. We hypothesized that upregulation of the systemic or brain immune response has an augmenting effect by potentially increasing the interplay between the neuronal and immune systems during the growth of the MIA offspring. In this study, a C57BL/6j MIA female offspring model exhibiting social deficits was established. The expression of fetal interferon (IFN)-stimulated (gbp3, irgm1, ifi44), adolescent immunodevelopmental transcription factor (eg, r2, tfap2b), hormone (pomc, hcrt), adult selectin (sell, selp) and neuroligin (nlgn2) genes was altered. Systemic upregulation of endogenous IL-10 occurred at the adult stage, while both IL-1β and IL-6 were increased and persisted in the sera throughout the growth of the MIA offspring. The cerebral IL-6 levels were endogenously upregulated, but both MCP-1 (macrophage inflammatory protein-1) and L-selectin levels were downregulated at the adolescent and/or adult stages. However, the MIA offspring were susceptible to lipopolysaccharide (LPS) stimulation. After reinjecting the MIA offspring with LPS in adulthood, a variety of sera and cerebral cytokines, chemokines and CAMs were increased. Particularly, both MCP-1 and L-selectin showed relatively high expression in the brain compared with the expression levels in phosphate-buffered saline (PBS)-treated offspring injected with LPS. Potentially, MCP-1 was attracted to the L-selectin-mediated immune cells due to augmentation of the immune response following stimulation in MIA female offspring.

Accelerated hyperfractionation field-involved re-irradiation combined with concurrent capecitabine chemotherapy for locally recurrent and irresectable rectal cancer

OBJECTIVES

To evaluate the efficacy and treatment-related toxicity of accelerated hyperfractionation field-involved re-irradiation combined with concurrent capecitabine chemotherapy for locally recurrent and irresectable rectal cancer (LRIRC).

METHODS

72 patients with LRIRC who underwent the treatment were studied. Three-dimensional conformal accelerated hyperfractionation radiotherapy (3D-CAHRT) was performed and the dose was delivered with a schedule of 1.2 Gy twice daily, with an interval of at least 6 h between fractions, 5 days a week. Concurrent capecitabine chemotherapy was administered twice daily. After 36 Gy in 30 fractions over 3 weeks, patients were evaluated to define the resectability of the disease. If resection was not feasible irradiation was resumed until the total dose administered to the tumour reached 51.6-56.4 Gy.

RESULTS

Two patients temporarily interrupted concurrent chemoradiation because of Grade IV diarrhoea. The remaining 70 patients completed the planned concurrent chemoradiation. In all patients, the complete response rate was 8.3% and the partial response rate was 51.4%. The overall response rate was 59.7% and clinical benefit rate was 93.1%. Symptomatic responses proved to be obvious and tumour resection was performed in 18 patients. The overall median survival time and median progression-free survival time were 32 and 17 months, respectively. 3 year overall survival and progression-free survival were 45.12% and 31.19%, respectively. Severely acute toxicities included Grade III-IV diarrhoea and granulocytopenia with 9.7% and 8.3% incidence respectively. Small bowel obstruction was severely late toxicity, and the incidence was 1.4%.

CONCLUSION

Three-dimensional conformal accelerated hyperfractionation field-involved re-irradiation combined with concurrent capecitabine chemotherapy might be an effective and well-tolerated regimen for patients with LRIRC.

Antiplatelet autoantibodies elicited by dengue virus non-structural protein 1 cause thrombocytopenia and mortality in mice

BACKGROUND

The mechanisms responsible for thrombocytopenia associated with dengue fever (DF) and dengue hemorrhage fever (DHF) remain unclear.

OBJECTIVE

In this study, we investigated the pathogenic effects of dengue virus (DENV) non-structural protein 1 (NS1) on the elicitation of platelet cross-reactive antibodies.

RESULTS

The results showed that anti-DENV NS1 immunoglobulins (Igs) derived from both patients with DF/DHF and recombinant NS1-immunized rabbits could opsonize normal human platelets and enhance platelet-macrophage engagements in vitro. In addition, treatments with anti-NS1 Igs abnormally activated human platelets and induced thrombocytopenia in mice. These prothrombotic characteristics of anti-NS1 Ig might increase the disease burden of coagulant-aberrant DHF patients. To test this hypothesis, we injected anti-NS1 Igs into C57BL/6J mice that were preconditioned into a hypercoagulable state by warfarin treatments. When given before but not after platelet-lysate pre-adsorption, the anti-NS1 Igs injection treatments significantly increased mortality, fibrin deposition in lung, and plasma D-dimer levels, but significantly decreased anticoagulant proteins C, protein S and antithrombin III.

CONCLUSIONS

These results suggest that the platelet-bound antibody fractions of anti-NS1 Ig are prothrombotic, which might exacerbate the severity of disease in hosts with an imbalanced coagulant system.

Intraportal donor bone marrow transplantation improves intestinal allograft survival in rats under FK506-based immunosuppression

Donor-specific immunosuppression is important in transplant surgery. We examined the effect of intraportal donor-specific bone marrow transplantation on heterotopic small bowel transplantation in the high responder rat combination, ACI to Lewis. The study comprised five treatment groups: untreated controls (group 1); FK506 alone (group 2); low-dose predonine + FK506 (group 3); high-dose predonine + FK506 (group 4); and intraportal donor-specific bone marrow transplantation + FK506 (group 5). Intraportal transplantation was performed pre-operatively and FK506 and predonine given post-operatively. Intestinal allograft survival and changes of intragraft cytokine expression were analysed using the reverse transcription polymerase chain reaction. Allograft survival (mean +/- SD) was lowest in group 1 and greatest in group 5. The group 5 treatment regimen also down-regulated interferon-gamma and interleukin-2 transcription in the transplanted intestine. Intraportal donor bone marrow transplant combined with FK506 immunosuppression was found therefore to be the most beneficial treatment regimen.

Restricted expression of LUZP in neural lineage cells: a study in embryonic stem cells

A novel protein LUZP with 3 leucine zipper motifs at its amino terminus is predominantly expressed in the adult brain. A modified gene targeting approach was employed in an attempt to establish in vitro and in vivo models in which Luzp is knock-out (KO) for phenotype assessment and a reporter gene lacZ is knock-in (KI) for tracing its expression. We report in this study the molecular cloning of the Luzp gene, its targeting vector construction and Luzp-KO/lacZ-KI embryonic stem (ES) clone selection. Since LUZP is also expressed in ES cells, the possibility of embryonic lethality cannot be excluded when attempting to establish Luzp-null mutant mice. We have therefore examined the development of homozygous Luzp-KO/lacZ-KI clones in nude mice. Tissue types derived from all three embryonic germ layers were observed in teratomas developed in nude mice. In situ X-gal staining further revealed restricted expression of LUZP in neural lineage cells.

Essential role of Drosophila Hdac1 in homeotic gene silencing

Deacetylation of the N-terminal tails of core histones plays a crucial role in gene silencing. Rpd3 and Hda1 represent two major types of genes encoding trichostatin A-sensitive histone deacetylases. Although they have been widely found, their cellular and developmental roles remain to be elucidated in metazoa. We show that Drosophila Hdac1, an Rpd3-type gene, interacts cooperatively with Polycomb group repressors in silencing the homeotic genes that are essential for axial patterning of body segments. The biochemical copurification and cytological colocalization of HDAC1 and Polycomb group repressors strongly suggest that HDAC1 is a component of the silencing complex for chromatin modification on specific regulatory regions of homeotic genes.

Identification, molecular characterization, and chromosomal localization of the cDNA encoding a novel leucine zipper motif-containing protein

cDNA clones encoding a novel protein (LUZP) with three leucine zipper motifs were first identified from a murine bone marrow cDNA library. After screening two additional cDNA libraries of activated peritoneal exudate cells, 32 positive clones were obtained from 1.3 x 10(7) phage plaques. Four overlapping clones constituting a total of 7399 bp were sequenced on both strands. The complete open reading frame of LUZP is 1067 amino acids. In addition to three leucine zipper motifs located at the NH2 terminus, there are three nuclear localization signals and a large number of putative Ser/Thr phosphorylation sites. Western blot analyses indicate that LUZP is predominantly expressed in brain, whereas immunocytochemistry data clearly reveal its presence in the nucleus of neurons. Interspecific backcross analyses have mapped Luzp to mouse chromosome 4 in proximity to Gpcr14. Comparative mapping data suggest that the human homolog of Luzp will map to human chromosome 1p36.