Abstract PD3-18: The NSABP/NRG 8-gene signature accurately predicts degree of benefit from trastuzumab in Alliance/NCCTG N9831: Validation of the 8-gene signature in an independent clinical trial

BACKGROUND

Clinical trials NRG/NSABP B-31 and Alliance/NCCTG N9831 demonstrated that trastuzumab added to chemotherapy extended disease-free survival (DFS) in breast cancer patients (pts) in the adjuvant setting (Romond et al). However, the degree of trastuzumab benefit varies among pts. We previously described an 8-gene model that was predictive for trastuzumab benefit, which was validated in an independent cohort of B-31 patients (Pogue-Geile 2013). The 8-gene signature subtyped B-31 pts in an independent validation cohort into three trastuzumab benefit groups: one with large benefit HR=0.27, one with medium benefit HR=0.56, and one with little to no benefit HR=1.56. The purpose of this study was to validate the 8-gene model in pts enrolled into N9831, which tested the efficacy of adding trastuzumab to doxorubicin plus cyclophosphamide → paclitaxel by randomizing pts into one of three arms: chemotherapy only (Arm A), trastuzumab given after chemotherapy (Arm B), or trastuzumab given concurrently with chemotherapy (Arm C).

METHODS

NCounter data, consisting of 8 predictive genes and 4 house-keeping genes, for 1,379 patients enrolled into N9831 were used to assign each patient to one of the three benefit groups. Assignments to one of the three trastuzumab benefit groups based on the 8-gene model were made by the NSABP/NRG Pathology Laboratory Biostatistician, who was blinded to outcome data. Predictions were sent to N9831 investigators and accuracy of predictions were tested in pts enrolled into arms A and C (N=892) using Cox models adjusted for age, nodes, ER/PR status, tumor size, and grade. Recurrence-free survival (RFS) and DFS were used as endpoints.

RESULTS

Tumors from N9831were placed into one of the three trastuzumab benefit groups based on the 8-gene signature. The N9831 pts in the predicted-large benefit group had a hazard ratio (HR) of 0.47, P=0.0006, pts in the predicted-medium benefit group had an HR of 0.6, P=0.02, and the predicted-low benefit group had an HR of 1.54, P=0.375. The interaction P value was significant at 0.019 in adjusted Cox models. The RFS at 10 years for trastuzumab-treated pts was 72%, 83%, and 83% in the low, medium, and large benefit groups, respectively.

CONCLUSIONS

The 8-gene signature developed in a discovery cohort and validated in an independent cohort of B-31 pts has now been validated in N9831. Many anti-HER2 therapies such as lapatinib, afatinib, neratinib, pertuzumab, and TDM-1 have been approved for treatment in metastatic breast cancer pts and although these agents have shown responses, the actual improvements in outcomes in pts is variable and it is not known which pts actually receive benefit. Thus this signature may be clinically useful in identifying pts who may benefit from additional treatment beyond trastuzumab or for stratification of pts enrolled into clinical trials testing new anti-HER2 therapies.

SUPPORT

U10CA180868, -180822, UG1CA189867, U24CA196067, the PA DOH, which disclaims certain responsibilities, Genentech, Inc., and the Breast Cancer Research Foundation.

Citation Format: Pogue-Geile KL, Song N, Serie DJ, Thompson EA. The NSABP/NRG 8-gene signature accurately predicts degree of benefit from trastuzumab in Alliance/NCCTG N9831: Validation of the 8-gene signature in an independent clinical trial [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD3-18.

Rankl expression predicts poor prognosis in gastric cancer patients: results from a retrospective and single-center analysis

The receptor activator of nuclear factor κB ligand (RANKL)/RANK pathway plays an important role in the prognosis of several solid tumor types, but its role in gastric cancer prognosis has been poorly characterized. A total of 116 gastric cancer patients who underwent surgical resection were enrolled in this study. Expressions of RANKL and RANK in gastric cancer tissues were detected using immunohistochemical staining. Thirty-eight patients (33%) showed a high level of RANKL expression and 61 patients (53%) showed a high level of RANK expression. There was a positive correlation between expressions of RANKL and RANK (P=0.014, r=0.221). A high level of RANKL expression indicated shorter overall survival (OS) (P=0.008), and was associated with a higher pathological tumor/lymph node/metastasis (pTNM) stage (P=0.035), while no significant correlation was detected between RANK expression and clinicopathological parameters. RANKL also predicted poor prognosis in patients with high RANK expression (P=0.008) and Bormann's type III/IV (P=0.002). Furthermore, RANKL expression correlated with pTNM stage according to high RANK expression (P=0.009), while no significance was found in patients with low RANK expression (P=1.000). Together, our results revealed that high expression of RANKL could predict worse outcomes in gastric cancer especially combined with RANK detection, and thereby this pathway could be a useful prognostic indicator of gastric cancer.

Exosomes promote cetuximab resistance via the PTEN/Akt pathway in colon cancer cells

Cetuximab is widely used in patients with metastatic colon cancer expressing wildtype KRAS. However, acquired drug resistance limits its clinical efficacy. Exosomes are nanosized vesicles secreted by various cell types. Tumor cell-derived exosomes participate in many biological processes, including tumor invasion, metastasis, and drug resistance. In this study, exosomes derived from cetuximab-resistant RKO colon cancer cells induced cetuximab resistance in cetuximab-sensitive Caco-2 cells. Meanwhile, exosomes from RKO and Caco-2 cells showed different levels of phosphatase and tensin homolog (PTEN) and phosphor-Akt. Furthermore, reduced PTEN and increased phosphorylated Akt levels were found in Caco-2 cells after exposure to RKO cell-derived exosomes. Moreover, an Akt inhibitor prevented RKO cell-derived exosome-induced drug resistance in Caco-2 cells. These findings provide novel evidence that exosomes derived from cetuximab-resistant cells could induce cetuximab resistance in cetuximab-sensitive cells, by downregulating PTEN and increasing phosphorylated Akt levels.

Overexpression of AtPAD4 in transgenic Brachypodium distachyon enhances resistance to Puccinia brachypodii

Brachypodium distachyon (L.) has recently emerged as a model for temperate grasses for investigating the molecular basis of plant-pathogen interactions. Phytoalexin deficient 4 (PAD4) plays a regulatory role in mediating expression of genes involved in plant defence. In this research, we generated transgenic B. distachyon plants constitutively overexpressing AtPAD4. Two transgenic B. distachyon lines were verified using PCR and GUS phenotype. Constitutive expression of AtPAD4 in B. distachyon enhanced resistance to Puccinia brachypodii. P. brachypodii generated less urediniospores on transgenic than on wild-type plants. AtPAD4 overexpression enhanced salicylic acid (SA) levels in B. distachyon-infected tissues. qRT-PCR showed that expression of pathogenesis-related 1 (PR1) and other defence-related genes were up-regulated in transformed B. distachyon following infection with P. brachypodii. Our results indicate that AtPAD4 overexpression in B. distachyon plants led to SA accumulation and induced PR gene expression that reduced the rate of colonisation by P. brachypodii.

Mycobacterium tuberculosis protease MarP activates a peptidoglycan hydrolase during acid stress

Mycobacterium tuberculosis (Mtb) can persist in the human host in a latent state for decades, in part because it has the ability to withstand numerous stresses imposed by host immunity. Prior studies have established the essentiality of the periplasmic protease MarP for Mtb to survive in acidified phagosomes and establish and maintain infection in mice. However, the proteolytic substrates of MarP that mediate these phenotypes were unknown. Here, we used biochemical methods coupled with supravital chemical probes that facilitate imaging of nascent peptidoglycan to demonstrate that during acid stress MarP cleaves the peptidoglycan hydrolase RipA, a process required for RipA's activation. Failure of RipA processing in MarP-deficient cells leads to cell elongation and chain formation, a hallmark of progeny cell separation arrest. Our results suggest that sustaining peptidoglycan hydrolysis, a process required for cell elongation, separation of progeny cells, and cell wall homeostasis in growing cells, may also be essential for Mtb's survival in acidic conditions.

Development and characterization of microsatellite markers of the eastern keelback mullet (Liza affinis)

Twenty-four polymorphic microsatellite loci were isolated and characterized for Liza affinis using a (GT)13-enriched genomic library. The number of alleles per locus ranged from 3 to 9, with a mean number of 6.250. The observed and expected heterozygosities ranged from 0.417 to 1.000 and from 0.550 to 0.861, with an average of 0.859 and 0.779, respectively. Deviation from Hardy-Weinberg proportions was detected at three loci. Evidence of null alleles was found at two loci. These markers will be useful in further studies investigating the genetic variation and population structure of this species, and may provide insights into the maintenance and efficient management of eastern keelback mullet resources.

Development of polymorphic microsatellite loci for a new fish species, Chinese sillago (Sillago sinica)

Sillago sinica is a newly identified species belonging to Sillaginidae, Perciforms, and was found along the coast of China in 2011. In the present study, 81 microsatellite loci were isolated from an enriched genomic library, and 24 positive clones containing microsatellite repeats had adequate flanking sequences for the development of PCR primers. Sixteen of these primers were monomorphic or would not amplify. Eight were polymorphic in an examined population with the number of alleles per locus ranging from 2 to 14. The number of observed and expected heterozygosities per locus varied from 0.125 to 0.958 and from 0.120 to 0.904, respectively. The polymorphism information content ranged from 0.110 to 0.721. All loci conformed to Hardy-Weinberg equilibrium (P > 0.05) after Bonferroni correction. There was no significant linkage disequilibrium between the eight polymorphic loci. These results suggest that these markers may be very useful for the characterization of natural populations of this species.

Association of CRTC2 gene polymorphisms with growth and meat quality traits of Qinchuan cattle

Growth and meat quality traits play important roles in the evaluation of cattle productivity and are influenced by genetic and environmental factors. CRTC2 is a recently discovered gene related to obesity that may influence fat deposition. The aim of the current study was to detect polymorphisms of bovine CRTC2 and explore their relationships to growth and meat quality in Qinchuan cattle. Three single nucleotide polymorphisms (SNPs); g.3001 C>T; g.3034 G>A; and g.3467 T>C, were identified from sequencing results of 422 Qinchuan cattle. The genotypic distributions of both g.3034 G>A and g.3467 T>C mutations were in agreement with Hardy-Weinberg equilibrium, (P < 0.05), while the T3001C mutation was not (P > 0.05), based on χ(2) test analysis. The SNPs g.3001 C>T and g.3034 G>A are missense mutations (Ser/Phe and Ser/Thr respectively). Additionally, SNPs g.3034 G>A and g.3467 T>C showed a medium polymorphism level (0.25 < PIC< 0.50), whereas g.3001 C>T showed a low polymorphism level (PIC < 0.25). These three SNPs were significantly associated with several growth and meat quality traits in the Qinchuan cattle population (P < 0.05 or P < 0.01). Collectively, these results demonstrate that CRTC2 is involved in the regulation of cattle growth and meat quality, and suggest that CRTC2 is a potential candidate gene for marker-assisted selection in future breeding development programs for Qinchuan cattle.

Identification of single nucleotide polymorphisms of the signal transducer and activator of transcription 3 gene (STAT3) associated with body measurement and carcass quality traits in beef cattle

Previous studies have shown that the signal transducer and activator of transcription 3 gene (STAT3) is involved in lipid storage and energy metabolism, suggesting that STAT3 is a potential candidate gene that affects body measurement and carcass quality traits in animals. Therefore, the aim of this study was to identify polymorphisms in bovine STAT3 and to analyze their possible associations with body measurement and carcass quality traits in 493 individuals of 2 native Chinese cattle breeds: Qinchuan (N = 371) and Jiaxian cattle (N = 122). DNA sequencing and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) were employed to detect STAT3 single nucleotide polymorphisms (SNPs). We found 5 SNPs: 1 in an exon (g.65812G>A: exon 16) and 4 in introns (g.43591G>A: 13 intron, g.67492T>G: 19 intron, g.67519T>C: 19 intron, and g.68964G>A: 20 intron). Both g.65812G>A and g.68964G>A were not in Hardy- Weinberg equilibrium (HWE), whereas individual frequencies of each genotype were consistent with HWE for other SNPs in Qinchuan cattle populations. For the Jiaxian cattle, the genotype distributions of the 4 mutations were in HWE except for g.67519T>C. The results indicate that these SNPs have a significant association with some body measurements and carcass quality traits (P < 0.05 or P < 0.01). Therefore, STAT3 might have potential effects on production traits in beef cattle populations and could be used for marker-assisted selection.

Clinical and laboratory characteristics of systemic sclerosis patients with pulmonary arterial hypertension in China

OBJECTIVES

Pulmonary arterial hypertension (PAH) is associated with significant morbidity and mortality, especially in systemic sclerosis (SSc). Since there was no published study regarding PAH in the Chinese SSc population, we aimed to describe a cohort to provide some data for early diagnosis.

METHODS

We evaluated 236 systemic sclerosis patients prospectively registered in the EUSTAR (European League Against Rheumatism Scleroderma Trial and Research Group) database from the Peking Union Medical College Hospital from 2009 to 2012. Among them, 33 individuals received right heart catheterisations (RHC) while the remaining patients were grouped by echocardiographic data. These patients were classified into two groups, PAH and non-PAH group. Their clinical and laboratory features were statistically analysed to identify possible risk factors for PAH in Chinese SSc population.

RESULTS

The possible prevalence of PAH in SSc patients was approximately 11% in our study. Digital ulcers (52.0% vs. 31.2%), telangiectasias (64.0% vs. 37.6%) and gastroesophageal reflux disease (GERD) (60.0% vs. 36.2%) were more common in SSc patients with PAH. Some laboratory results were also proved to be significantly correlated with it. Logistic regression analysis showed that telangiectasias (OR=2.888, 95% CI=1.176-7.093), presence of GERD (OR=2.592, 95% CI=1.067-6.296), anti-RNP positivity (OR=24.384, 95% CI=1.978-36.651), IgA level elevation (OR=8.745, 95% CI 4.838-122.896) and FVC/TLCO ratio (OR=97.067, 95% CI 12.475-755.271) were associated with an increased odds for PAH in SSc patients.

CONCLUSIONS

This study described possible predictors of PAH in Chinese SSc population, which have been supported by similar studies in other ethnic groups.

Proteomic pattern changes associated with obesity-induced asthenozoospermia

Obesity, an increasingly frequent societal disease can also be accompanied by declines in spermatozoa quality and male subfecundity. To determine if there are obesity-associated proteomic changes potentially affecting sperm quality and motility, differential proteomic analysis was performed on spermatozoa from both obesity-associated asthenozoospermia and clinically healthy individuals, using a label-free quantitative LC-MS/MS approach. We resolved 1975 proteins in the human sperm proteome, amongst which, 105 proteins were less abundant, whereas 22 other proteins increased in obesity-associated asthenozoospermia. Functional category analyses indicated that the differentially expressed proteins are mainly related to cytoskeletal regulation, vesicle biogenesis, metabolism, and protein degradation involved in spermiogenesis and sperm motility. Furthermore, declines in endoplasmic reticulum protein 57 (ERp57) and actin-binding-related protein T2 (ACTRT2) expression were verified by immunofluorescence, Western blot, and flow cytometry analyses. It is evident that ERp57 is localized in the acrosome region, neck and principal piece of human spermatozoa, whereas ACTRT2 is localized in the post-acrosomal region and middle piece. Thus, these differences in protein expression in asthenozoospermia may contribute to the underlying sperm quality defects afflicting these individuals. Notably, declines in ERp57 and ACTRT2 expression in obesity-associated asthenozoospermia may play critical roles in reducing sperm motility.

[Lentivirus-mediated siRNA targeting sae1 induces cell cycle arrest and apop- tosis in colon cancer cell RKO]

Deregulated expression of proteins involved in the SUMOylation pathway has been detected in several tumors. SUMO1-activating enzyme subunit 1 (SAE1) plays an important role in this process. We found that SAE1 was highly expressed in the colon cancer cell line RKO and used lentivirus-mediated siRNA to suppress SAE1 expressionin RKO cells. RNA-interference efficiently and specifically downregulated the target gene expression in RKO on both mRNA and protein levels. Silencing of SAE1 inhibited proliferation and reduced colony formation of RKO cells. Furthermore, as it has been shown by flow cytometry analysis, specific knockdown of SAE1 slowed down the cell population at G0/G1 phase and induced apoptosis of RKO cells. On the base of results obtained, one can suppose the biological significance of SAE1 in colon tumorigenesis and a use of this protein as a novel molecular target for colon cancer therapy.

Pro-inflammatory cytokine-mediated ferroportin down-regulation contributes to the nigral iron accumulation in lipopolysaccharide-induced Parkinsonian models

Pro-inflammatory cytokines induced by inflammation and iron accumulation in the substantia nigra (SN) have been implicated in the pathogenesis of Parkinson's disease (PD). In the present study, we aimed to investigate the relationship between inflammation and iron accumulation in a lipopolysaccharide (LPS)-induced Parkinsonian rat model. The activation of glial cells and elevated levels of pro-inflammatory cytokines were observed in the SN of LPS models, accompanied by iron deposits in the same region. Moreover, ferroportin (Fpn), the only channel for iron export, was down-regulated. SH-SY5Y dopaminergic cells were pre-incubated with conditioned media enriched in pro-inflammatory cytokines, and abnormal iron deposits and a drop of Fpn were observed. The expression of heme oxygenase-1 (HO-1) was also upregulated in vivo and in vitro. These results suggested that pro-inflammatory cytokines might induce Fpn downregulation, which leads to iron accumulation and dopaminergic neurons' degeneration in PD. HO-1 may also contribute to the iron accumulation in neurons, but its mechanism needs to be further investigated.

Identification of UV-B-induced microRNAs in wheat

MicroRNAs (miRNAs) play critical roles in post-transcriptional gene regulation and act as important endogenous regulators to various stressors. Ultraviolet-B (UV-B) radiation is a major factor influencing crop growth and development. In this study, we isolated a novel wheat miRNA, named Tae-miR6000, and confirmed its expression diversity after UV-B treatments. Additionally, using the Northern blotting technique, we found that six miRNAs were highly responsive to UV-B stress in wheat. Of these six miRNAs, miR159, miR167a, and miR171 were significantly upregulated, and the remaining three miRNAs were downregulated, at different time points after UV-B treatment. This result indicates that miRNAs may be involved in the regulation of targets after induction by UV-B stress. Furthermore, promoter analysis of the UV-B-responsive miRNA genes revealed some light-relevant cis-elements, such as the I-box and G-box. Taken together, the results of this study suggest that wheat miRNAs play important roles in the response to UV-B stress.

Population genetic structure and geographical differentiation of burbot (Lota lota) in China

The burbot (Lota lota Linnaeus, 1758) is the only freshwater species of the family Gadidae. There is a long-standing controversy about taxonomic status of the burbot from the Amur River basin. It is necessary to investigate population genetic structure and geographical differentiation among burbot populations from the Irtysh River basin and Amur River basin by mitochondrial DNA nucleotide sequence analysis. A 572 bp segment of cytochrome b and 425 bp segment of control region gene were sequenced from 4 populations. The results showed that there was lower genetic diversity of burbot in China and highly significant genetic difference between populations in the Amur Riverbasin (P < 0.01). Demographic analysis indicated that the burbot from the Amur River basin experienced population expansion (Cytb: F(s) = -0.912 (P = 0.287), D = -0.399 (P = 0.375); CR: F(s) = -4.771 (P = 0.015), D = -1.523 (P = 0.03 )). The data of 4 populations in China combining with the published data representing the Eurasian and North American burbot, revealed three distinct phylogenetic lineages (labelled EB, NA, Amur).