Functional Germline Research Articles

Functional germline variants in DNA damage repair pathways are associated with altered survival in adults with glioma treated with temozolomide.

Temozolomide (TMZ) treatment has demonstrated, but variable, impact on glioma prognosis. This study examines associations of survival with DNA repair gene germline polymorphisms among glioma patients who did and did not have TMZ treatment. Identifying genetic markers which sensitize tumor cells to TMZ could personalize therapy and improve outcomes. We evaluated TMZ-related survival associations of pathogenic germline SNPs and genetically predicted transcript levels within 34 DNA repair genes among 1504 glioma patients from the UCSF Adult Glioma Study and Mayo Clinic whose diagnoses spanned pre- and post-TMZ eras within the major known glioma prognostic molecular subtypes. Among those who received TMZ, 5 SNPs were associated with overall survival, but not in those who did not receive TMZ. Only rs2308321-G, in MGMT , was associated with decreased survival (HR=1.21, p=0.019) for all glioma subtypes. Rs73191162-T (near UNG ), rs13076508-C (near PARP3 ), rs7840433-A (near NEIL2 ), and rs3130618-A (near MSH5 ) were only associated with survival and TMZ treatment for certain subtypes, suggesting subtype-specific germline chemo-sensitization. Genetically predicted elevated compared to normal brain expression of PNKP was associated with dramatically worse survival for TMZ-treated patients with IDH -mutant and 1p/19q non-codeleted gliomas (p=0.015). Similarly, NEIL2 and TDG expressions were associated with altered TMZ-related survival only among certain subtypes. Functional germline alterations within DNA repair genes were associated with TMZ sensitivity, measured by overall survival, among adults with glioma, these variants should be evaluated in prospective analyses and functional studies. We observed SNPs associated with glioma survival, specific to cases receiving TMZ An MGMT variant may reduce glioma survival indirectly through myelosuppression Decreased genetic PNKP expression in the brain may sensitize cells to TMZ. The introduction of temozolomide (TMZ) as a part of standard-of-care in the treatment of gliomas marked the last notable increase in patient survival. However, the effectiveness of TMZ is not universal, and can result in serious complications. The mechanism of action behind the drug is the introduction of damaging methyl groups across the tumor genome and leveraging of DNA damage repair (DDR) mechanisms to signal programmed cell death. Previous literature has identified that defects in DDR mechanisms can alter TMZ sensitivity. Using a unique dataset that spans the pre- and post-TMZ eras, we demonstrate that germline variation in DDR-related genes may have significant impact on overall survival for patients treated with TMZ, with no effects observed in the pre-TMZ era. This suggests that germline variants in these DDR genes could be used to personalize TMZ therapy to improve patient survival.

Germline functional variants contribute to somatic mutation and outcomes in neuroblastoma.

Germline genetic context may play a significant role in the development and evolution of cancer, particularly in childhood cancers such as neuroblastoma. This study investigates the role of putatively functional germline variants in neuroblastoma, even if they do not directly increase disease risk. Our whole-exome sequencing analysis of 125 patients with neuroblastoma reveals a positive correlation between germline variant burden and somatic mutations. Moreover, patients with higher germline variant burden exhibit worse outcomes. Similar findings are observed in the independent neuroblastoma cohort where a higher germline variant burden correlates with a higher somatic mutational burden and a worse overall survival outcome. However, contrasting results emerge in adult-onset cancer, emphasizing the importance of germline genetics in neuroblastoma. The enrichment of putatively functional germline variants in cancer predisposition genes is borderline significant when compared to healthy populations (P = 0.077; Odds Ratio, 1.45; 95% confidence intervals, 0.94-2.21) and significantly more pronounced against adult-onset cancers (P = 0.016; Odds Ratio, 2.13; 95% confidence intervals, 1.10-3.91). Additionally, the presence of these variants proves to have prognostic significance in neuroblastoma (log-rank P < 0.001), and combining germline with clinical risk factors notably improves survival predictions.

The 18S rRNA Methyltransferase DIMT-1 Regulates Lifespan in the Germline Later in Life.

Ribosome heterogeneity has emerged as an important regulatory control feature for determining which proteins are synthesized, however, the influence of age on ribosome heterogeneity is not fully understood. Whether mRNA transcripts are selectively translated in young versus old cells and whether dysregulation of this process drives organismal aging is unknown. Here we examined the role of ribosomal RNA (rRNA) methylation in maintaining appropriate translation as organisms age. In a directed RNAi screen, we identified the 18S rRNA N6'-dimethyl adenosine (m6,2A) methyltransferase, dimt-1, as a regulator of C. elegans lifespan and stress resistance. Lifespan extension induced by dimt-1 deficiency required a functional germline and was dependent on the known regulator of protein translation, the Rag GTPase, raga-1, which links amino acid sensing to the mechanistic target of rapamycin complex (mTORC)1. Using an auxin-inducible degron tagged version of dimt-1, we demonstrate that DIMT-1 functions in the germline after mid-life to regulate lifespan. We further found that knock-down of dimt-1 leads to selective translation of transcripts important for stress resistance and lifespan regulation in the C. elegans germline in mid-life including the cytochrome P450 daf-9, which synthesizes a steroid that signals from the germline to the soma to regulate lifespan. We found that dimt-1 induced lifespan extension was dependent on the daf-9 signaling pathway. This finding reveals a new layer of proteome dysfunction, beyond protein synthesis and degradation, as an important regulator of aging. Our findings highlight a new role for ribosome heterogeneity, and specific rRNA modifications, in maintaining appropriate translation later in life to promote healthy aging.

Abstract 7641: Prognostic impact of functional germline mutations in muscle-invasive bladder cancer identified by neural network analysis

Abstract Background: An accurate prognostic algorithm based on germline whole exome sequencing (WES) would complement tumor omics as a non-invasive source of biomarkers for guiding cancer patient therapy. In a previous study, we used WES and RNA-seq data from muscle-invasive bladder cancer (MIBC) and normal host cells to train a survival model, wherein we discovered that mutated germline genes accounted for 90% of feature importance. We have since defined a larger cohort to identify key germline biomarkers of overall survival (OS) that may be scalable for application in the clinic. Methods: 169 patients from The Cancer Genome Atlas (TCGA) with MIBC stages T2-T4 that underwent radical cystectomy (RC) w/o neoadjuvant treatment were eligible. OS at 4 years was the primary clinical endpoint as it is associated with death due to metastatic tumor recurrence. Patients were dichotomized to control survivors who were alive at 4+ years, and cases who died within 4 years but no less than 4 months after RC. 49 qualifying survivors were propensity matched against 49 dead patients by stage, adjuvant treatment, gender, race, and age. The remaining 71 dead patients served as a holdout. Only high (e.g. frameshift) and moderate (e.g. indel) impact germline variants were included. Mutations were weighted for allele frequency (penalize common) and genotype (reward homozygous) before grouping at the gene level. A panel of the 21 most differential genes in stratified patients were selected for neural network training using AIQC. The model forced protective/pathogenic genes to interact and produced individual survival probabilities. Gene importance was determined via permutation. Results: OS was accurately predicted for 98.2% of patients: 1 FN, 2 FP, 37 TN, 119 TP. The top 3 permuted genes (and related pathways) were: SORL1 (Aβ), KIF27 (hedgehog), CUL7 (p53). The most differential gene was CUL7: 31% of survivors mutated vs 2% of dead. Conclusion: Neural network analysis identified the promise of germline genetics as an accurate predictor of survival and tumor recurrence in MIBC patients. Upon validation in an external cohort, these biomarkers could be used to inform adjuvant therapy and complement molecular residual disease alongside circulating tumor (ct)-DNA. Citation Format: Guru P. Sonpavde, Amin H. Nassar, Arvind Ravi, Layne Sadler. Prognostic impact of functional germline mutations in muscle-invasive bladder cancer identified by neural network analysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7641.

KMT2A-D pathogenicity, prevalence, and variation according to a population database.

The KMT2 family of genes is essential epigenetic regulators promoting gene expression. The gene family contains three subgroups, each with two paralogues: KMT2A and KMT2B; KMT2C and KMT2D; KMT2F and KMT2G. KMT2A-D are among the most frequent somatically altered genes in several different cancer types. Somatic KMT2A rearrangements are well-characterized in infant leukemia (IL), and growing evidence supports the role of additional family members (KMT2B, KMT2C, and KMT2D) in leukemogenesis. Enrichment of rare heterozygous frameshift variants in KMT2A and C has been reported in acute myeloid leukemia (AML), IL, and solid tumors. Currently, the non-synonymous variation, prevalence, and penetrance of these four genes are unknown. This study determined the prevalence of pathogenic/likely pathogenic (P/LP) germline KMT2A-D variants in a cancer-free adult population from the Genome Aggregation Database (gnomAD). Two methods of variant interpretation were utilized: a manual genomic variant interpretation and an automated ACMG pipeline. The ACMG pipeline identified considerably fewer P/LP variants (n=89) compared to the manual method (n=660) in all 4 genes. Consequently, the total P/LP prevalence and allele frequency (AF) were higher in the manual method (1:112, AF=4.46E-03) than in ACMG (1:832, AF=6.01E-04). Multiple ancestry-exclusive P/LP variants were identified along with an increased frequency in males compared to females. Many of these variants identified in this population database are also associated with severe juvenile conditions. These data demonstrate that putatively functional germline variation in these developmentally important genes is more common than previously appreciated and identification in cancer-free adults may indicate incomplete penetrance for many of these variants. Future research should examine a genetic predisposing role in IL and other pediatric cancers.

Mitochondrial genome recovery by ATFS-1 is essential for development after starvation

Nutrient availability regulates the C.elegans life cycle as well as mitochondrial physiology. Food deprivation significantly reduces mitochondrial genome (mtDNA) numbers and leads to aging-related phenotypes. Here we show that the bZIP (basic leucine zipper) protein ATFS-1, a mediator of the mitochondrial unfolded protein response (UPRmt), is required to promote growth and establish a functional germline after prolonged starvation. We find that recovery of mtDNA copy numbers and development after starvation requires mitochondrion-localized ATFS-1 but not its nuclear transcription activity. We also find that the insulin-like receptor DAF-2 functions upstream of ATFS-1 to modulate mtDNA content. We show that reducing DAF-2 activity represses ATFS-1 nuclear function while causing an increase in mtDNA content, partly mediated by mitochondrion-localized ATFS-1. Our data indicate the importance of the UPRmt in recovering mitochondrial mass and suggest that atfs-1-dependent mtDNA replication precedes mitochondrial network expansion after starvation.

The Continued Absence of Functional Germline Stem Cells in Adult Ovaries.

Ovaries are central to development, fertility, and reproduction of women. A particularly interesting feature of ovaries is their accelerated aging compared to other tissues, leading to loss of function far before other organs senesce. The limited pool of ovarian follicles is generated before birth and once exhausted, menopause will inevitably commence around the age of 50 years marking the end of fertility. Yet, there are reports suggesting the presence of germline stem cells and neo-oogenesis in adult human ovaries. These observations have fueled a long debate, created experimental fertility treatments, and opened business opportunities. Our recent analysis of cell types in the ovarian cortex of women of fertile age could not find evidence of germline stem cells. Like before, our work has been met with critique suggesting methodological shortcomings. We agree that excellence starts with methods and welcome discussion on the pros and cons of different protocols. In this commentary, we discuss the recent re-interpretation of our work.

Investigation of CDH1 germline mutations in Turkish patients with Kaposi’s sarcoma

Abstract Objectives Kaposi’s sarcoma (KS) develops from the lining cells of blood or lymphatic vessels and may appear as red, purple, brown, or black lesions. E-cadherin, CDH1, is a cell adhesion molecule located on the surface of epithelial cells. CDH1 gene expression is downregulated in several cancers and is considered a tumor suppressor gene involved in epithelial-mesenchymal transition in carcinomas. Loss of CDH1 gene expression is observed in many carcinomas, mainly diffuse gastric carcinomas and lobular breast carcinomas, as well as skin tumors. This study investigates the CDH1 germline mutations in HIV-negative (Human Immunodeficiency) Virus KS patients in the Turkish population. Methods The study examined 25 peripheral blood mononuclear cells from KS patients using the Sanger sequencing technique. Results Sixteen exons of the CDH1 gene were sequenced, and a pathogenic functional germline mutation, HET c.2245C &gt; T, p.(Arg749Trp) rs776975632, NM _004360.5, was identified in a patient with a family history of gastric and breast cancer with a high number of lesions compared to other KS patients. Discussion: KS patients with a family history of cancer could be screened for CDH1 gene and cancer-related-gen variants in the future. Conclusions KS is a rare malignancy, and genetic analysis will benefit KS patients. Further studies are needed to describe better the variations detected in a large number of KS patients in this study.

Abstract P3-07-01: Young women with breast cancer and high risk family history but no high penetrance germline mutations have a higher load of rare high functional impact germline variants in cancer relevant genes

Abstract Background: There is an incomplete understanding of why some women develop breast cancer 20-25 years earlier than the majority of women. Only 30-40% of women with high risk family history are found to have known cancer predisposing mutations. This phenomenon is referred to as “missing heredity”. We hypothesize that women with high-risk cancer family history but no known high penetrance cancer predisposing mutations who develop breast cancer at a young age have a higher deleterious load of germline high functional impact (gHFI) single nucleotide variants in cancer relevant genes. Methods: 94 women diagnosed with breast cancer age &amp;lt;50 with high risk cancer family history who tested negative for germline cancer predisposing mutations were identified at Yale Cancer Prevention Clinic (YCPC). 149 controls, healthy Caucasian individuals age &amp;gt; 65 with no cancer family history were identified from Yale Generations project. Whole-exome sequencing (WES) was performed on peripheral blood from 94 cases, 149 controls, and 42 matched tumors. WES data was analyzed from 1,112 female breast cancer cases with first-degree breast cancer family history and 50,887 healthy women without breast cancer family history from UKBiobank. Rare gHFI variants were defined as nonsynonymous variants predicted as deleterious in MetaSVM, or loss-of-function in gnormAD, or pathogenic in ClinVar database with mutation frequency &amp;lt;0.01. Hallmark genes were 1,558 genes involved in 21 cancer pathways and 83 cancer predisposition genes (CPGs). 468 somatic cancer genes were used. Rare gHFI in cases vs controls were compared using SNP-set (Sequence) Kernel Association Test (SKAT). Somatic mutations in YCPC vs 652 ER+ breast cancer TCGA cases were compared using 13/468 cancer genes mutated &amp;gt;5% of cases using Fisher’s exact test. FDRs were calculated using Benjamini &amp; Hochberg. Results: The majority of YCPC patients were Caucasian (78.7%), median age (43.5), with invasive ductal carcinoma (85.1%), ER+PR+HER2- (67.0%). YCPC patients had a higher average burden of rare gHFI variants in cancer hallmark genes (excluding CPGs) compared to controls (p=0.0075, adjusted for race), but did not show a higher germline burden in CPGs. Similarly, UKBiobank breast cancer patients with a family history had a higher germline variant burden in hallmark genes (excluding CPGs) compared to controls (p=0.0368). The main pathways affected by gHFI in the YCPC cohort were adaptive immunity (p=1.61 x 10-8) and extracellular matrix (p=0.0034). Thirty six (87.8%) YCPC matched tumors carried somatic mutations in known cancer related genes. Compared to TCGA, YCPC samples had fewer TP53 mutations (5% vs 17%, FDR = 0.27), but more mutations in CHEK2, GNAQ, APC, and SDHA (FDR&amp;lt;0.028). Conclusions: Our cohort of young women with breast cancer and high risk family history with no known germline high penetrance cancer gene mutations showed a higher burden of germline high functional impact variants in hallmark cancer genes. This higher germline variant burden suggests that the totality of gHFI variants in cancer related genes could explain why these women develop breast cancer at a younger age. CohortRace (%)AgeCases (N)Control (N)GenesetAverage Case BurdenAverage Case BurdenSKAT testYaleCaucasian (78.7)439414983 CPGs0.27660.30200.56921508 Hallmark4.23404.18790.0075UK BiobankBritish (100)5611125088783 CPGs0.37410.28064.19x10-51508 Hallmark3.36423.33990.0368 Citation Format: Mariya Rozenblit, Tao Qing, Yixuan Ye, Hongyu Zhao, Erin Hofstatter, Vinit Singh, Emily Reisenbichler, Michael Murray, Lajos Pusztai. Young women with breast cancer and high risk family history but no high penetrance germline mutations have a higher load of rare high functional impact germline variants in cancer relevant genes [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-07-01.

The enhancer rare germline variation rs548071605 contributes to lung cancer development.

Rare germline variations contribute to the missing heritability of human complex diseases including cancers. Given their very low frequency, discovering and testing disease-causing rare germline variations remains challenging. The tag-single nucleotide polymorphism rs17728461 in 22q12.2 is highly associated with lung cancer risk. Here, we identified a functional rare germline variation rs548071605 (A>G) in a p65-responsive enhancer located within 22q12.2. The enhancer significantly promoted lung cancer cell proliferation in vitro and in a xenograft mouse model by upregulating the leukemia inhibitory factor (LIF) gene via the formation of a chromatin loop. Differential expression of LIF and its significant correlation with first progression survival time of patients further supported the lung cancer-driving effects of the 22q-Enh enhancer. Importantly, the rare variation was harbored in the p65 binding sequence and dramatically increased the enhancer activity by increasing responsiveness of the enhancer to p65 and B-cell lymphoma 3 protein, an oncoprotein that assisted the p65 binding. Our study revealed a regulatory rare germline variation with a potential lung cancer-driving role in the 22q12.2 risk region, providing intriguing clues for investigating the "missing heritability" of cancers, and also offered a useful experimental model for identifying causal rare variations.

Heritable Variants in the Chromosome 1q22 Locus Increase Gastric Cancer Risk via Altered Chromatin Looping and Increased UBAP2L Expression.

Genome-wide association studies (GWAS) have implicated the 1q22 gastric cancer risk locus in disease, but little is known about its underlying oncogenic functions. This study represents a systematic investigation of the biological significance and potential mechanism associated with the gastric cancer risk of SNP rs2075570(C>T) in 1q22. We identified two functional germline variations (rs2049805-C and rs2974931-G) in an active enhancer in a 64.8 kb high-linkage disequilibrium block of rs2075570. The enhancer upregulated ubiquitin associated protein 2 like (UBAP2L) gene expression over a 960 kb distance by chromatin looping. Gastric cancer tissues expressed significantly higher levels of UBAP2L than was observed in the matched noncancerous tissues, and the UBAP2L expression was negatively correlated with patient survival. Downregulation of UBAP2L inhibited the proliferation and invasion of human gastric cancer cells in vitro and in a xenograft mouse model. Notably, the two mutant variations significantly enforced the enhancer activity and UBAP2L expression. In conclusion, this study revealed two causal variations in the 1q22 region using tag-SNP rs2075570 as a genetic marker. These variations may affect the occurrence and progression of gastric cancer by reinforcing the expression of the 1q22-Enh enhancer-regulated UBAP2L target gene. IMPLICATIONS: Our study provides an important clue of how noncoding germline variations contribute to gastric cancer, which gives a novel insight into understanding the genetic mechanism of gastric cancer.

EPCO-31. GERMLINE AND SOMATIC MUTATIONS IN PEDIATRIC GERM CELL TUMORS

Abstract Pediatric germ cell tumors (pGCTs), a group of germ-cell-originated neoplasms, currently lack sufficient study. Although somatic activation of KIT/AKT and RAS/MAPK pathways have been revealed, no driver mutations have been detected in most of GCT cases. To extensively explore germline and somatic mutations, we analyzed genomic and/or transcriptomic sequencing data of 236 pGCTs, including data from not only public datasets but also newly collected whole-genome-sequencing data of tumor samples together with case-unaffected-parents trios collected in Shanghai Xinhua Hospital. A new computational pipeline was developed and carried out to identify functional germline and somatic variants. Overall, &amp;gt; 30,000 germline and &amp;gt; 100,000 somatic mutations were detected and prioritized. Particularly, we found germline trisomy 21 in three cases, germline XXY in five cases, and one germline XO, demonstrating the enrichment of germline chromosomal abnormality in pGCTs (p-value &amp;lt; 0.0001). We identified 196 loss-of-function-like inherited germline mutations involving CBL (4/212), PTEN (3/212), TEX11 (2/212), and ATM (1/212). In addition, we detected 2,160 de novo germline mutations (DNMs), and showed an average of 69.7 DNMs per proband, which is compatible to the previously reported incidence. Moreover, we discovered recurrent somatic mutations in known driver genes such as KIT (27/110), KRAS (10/110), NRAS (4/110), MTOR (5/110), PTEN (3/110), and CBL (2/110). Interestingly, somatic hotspot RRAS2 mutations were detected in seven of 110 cases. Subsequent clinical association analysis showed that patients who harbored RRAS2 mutations were younger than those harboring KRAS mutations (p-value &amp;lt; 0.05). Somatic copy number changes were frequently observed, including chr12p+ (47/110), chr21q+ (47/110), chrX+ (34/110), chr13q- (27/110), and chr20q+ (26/110). Furthermore, we identified chromoplexy in nine out of 62 cases, and this alteration is significantly enriched in yolk sac tumors with the occurrence 7/11. Collectively, portraying the mutational landscape of pGCTs, we revealed its disease etiology and potential new drug targets.

Genetic Analysis of Functional Rare Germline Variants across Nine Cancer Types from an Electronic Health Record Linked Biobank.

Rare variants play an essential role in the etiology of cancer. In this study, we aim to characterize rare germline variants that impact the risk of cancer. We performed a genome-wide rare variant analysis using germline whole exome sequencing (WES) data derived from the Geisinger MyCode initiative to discover cancer predisposition variants. The case-control association analysis was conducted by binning variants in 5,538 patients with cancer and 7,286 matched controls in a discovery set and 1,991 patients with cancer and 2,504 matched controls in a validation set across nine cancer types. Further, The Cancer Genome Atlas (TCGA) germline data were used to replicate the findings. We identified 133 significant pathway-cancer pairs (85 replicated) and 90 significant gene-cancer pairs (12 replicated). In addition, we identified 18 genes and 3 pathways that were associated with survival outcome across cancers (Bonferroni P < 0.05). In this study, we identified potential predisposition genes and pathways based on rare variants in nine cancers. This work adds to the knowledge base and progress being made in precision medicine.

Somatic aging pathways regulate reproductive plasticity in Caenorhabditis elegans.

In animals, early-life stress can result in programmed changes in gene expression that can affect their adult phenotype. In C. elegans nematodes, starvation during the first larval stage promotes entry into a stress-resistant dauer stage until environmental conditions improve. Adults that have experienced dauer (postdauers) retain a memory of early-life starvation that results in gene expression changes and reduced fecundity. Here, we show that the endocrine pathways attributed to the regulation of somatic aging in C. elegans adults lacking a functional germline also regulate the reproductive phenotypes of postdauer adults that experienced early-life starvation. We demonstrate that postdauer adults reallocate fat to benefit progeny at the expense of the parental somatic fat reservoir and exhibit increased longevity compared to controls. Our results also show that the modification of somatic fat stores due to parental starvation memory is inherited in the F1 generation and may be the result of crosstalk between somatic and reproductive tissues mediated by the germline nuclear RNAi pathway.

Lrp6 Genotype affects Individual Susceptibility to Nonalcoholic Fatty Liver Disease and Silibinin Therapeutic Response via Wnt/β-catenin-Cyp2e1 Signaling.

Background: Nonalcoholic fatty liver disease (NAFLD) is a serious threat to human health worldwide, with a high genetic susceptibility. Rs2302685, a functional germline variant of LRP6, has been recently found to associate with NAFLD risk. This study was aimed to clarify the underlying mechanism associated with rs2302685 risk and its impact on pharmacotherapy in treatment of NAFLD.Methods: Venous blood samples were collected from NAFLD and non-NAFLD patients for SNP genotyping by using mass spectrometry. The Lrp6-floxdel mouse (Lrp6(+/-)) was generated to model the partial function associated with human rs2302685. The liver injury and therapeutic effects of silibinin were compared between Lrp6(+/-) and Lrp6(+/+) mice received a methionine-choline deficient (MCD) diet or normal diet. The effect of Lrp6 functional alteration on Wnt/β-catenin-Cyp2e1 signaling activities was evaluated by a series of cellular and molecular assays.Results: The T allele of LRP6 rs2302685 was confirmed to associate with a higher risk of NAFLD in human subjects. The carriers of rs2302685 had reduced level of AST and ALT as compared with the noncarriers. The Lrp6(+/-) mice exhibited a less severe liver injury induced by MCD but a reduced response to the treatment of silibinin in comparison to the Lrp6(+/+) mice, suggesting Lrp6 as a target of silibinin. Wnt/β-catenin-Cyp2e1 signaling together with ROS generation could be exacerbated by the overexpression of Lrp6, while decreased in response to Lrp6 siRNA or silibinin treatment under NAFLD modeling.Conclusions: The Lrp6 function affects individual susceptibility to NAFLD and the therapeutic effect of silibinin through the Wnt/β-catenin-Cyp2e1 signaling pathway. The present work has provided an underlying mechanism for human individual susceptibility to NAFLD associated with Lrp6 polymorphisms as well as a rationale for the effective use of silibinin in NAFLD patients.

Male reproductive aging arises via multifaceted mating-dependent sperm and seminal proteome declines, but is postponable in Drosophila

Declining ejaculate performance with male age is taxonomically widespread and has broad fitness consequences. Ejaculate success requires fully functional germline (sperm) and soma (seminal fluid) components. However, some aging theories predict that resources should be preferentially diverted to the germline at the expense of the soma, suggesting differential impacts of aging on sperm and seminal fluid and trade-offs between them or, more broadly, between reproduction and lifespan. While harmful effects of male age on sperm are well known, we do not know how much seminal fluid deteriorates in comparison. Moreover, given the predicted trade-offs, it remains unclear whether systemic lifespan-extending interventions could ameliorate the declining performance of the ejaculate as a whole. Here, we address these problems using Drosophila melanogaster. We demonstrate that seminal fluid deterioration contributes to male reproductive decline via mating-dependent mechanisms that include posttranslational modifications to seminal proteins and altered seminal proteome composition and transfer. Additionally, we find that sperm production declines chronologically with age, invariant to mating activity such that older multiply mated males become infertile principally via reduced sperm transfer and viability. Our data, therefore, support the idea that both germline and soma components of the ejaculate contribute to male reproductive aging but reveal a mismatch in their aging patterns. Our data do not generally support the idea that the germline is prioritized over soma, at least, within the ejaculate. Moreover, we find that lifespan-extending systemic down-regulation of insulin signaling results in improved late-life ejaculate performance, indicating simultaneous amelioration of both somatic and reproductive aging.

Dynamic Regulation of Adult-Specific Functions of the Nervous System by Signaling from the Reproductive System

Unlike juveniles, adult animals engage in suites of behaviors related to the search for and selection of potential mates and mating, including appropriate responses to sex pheromones. As in other species [1], male sex pheromones modulate several behaviors and physiological processes in C.elegans hermaphrodites [2-5]. In particular, one of these small-molecule signals, an ascaroside ascr#10, causes reduced exploration, more avid mating, and improved reproductive performance (see the accompanying paper by Aprison and Ruvinsky in this issue of Current Biology) [6]. Here, we investigated the mechanism that restricts pheromone response to adult hermaphrodites. Unexpectedly, we found that attainment of developmental adulthood was not alone sufficient for the behavioral response to the pheromone. To modify exploratory behavior in response to male pheromone, adult hermaphrodites also require functional germline and egg-laying apparatus. We show that this dependence of behavior on the reproductive system is due to feedback from the vulva muscles that reports ongoing reproduction to the nervous system. Our results reveal an activity-dependent conduit by which the reproductive system continuously licenses adult behaviors, including appropriate responses to the pheromones of the opposite sex. More broadly, our results suggest that signals from peripheral organs may serve as an important component of assuring age-appropriate functions of the nervous system.

Predisposing germline mutations in high hyperdiploid acute lymphoblastic leukemia in children.

High hyperdiploidy (HD) is the most common cytogenetic subtype of childhood acute lymphoblastic leukemia (ALL), and a higher incidence of HD has been reported in ALL patients with congenital cancer syndromes. We assessed the frequency of predisposing germline mutations in 57 HD-ALL patients from the California Childhood Leukemia Study via targeted sequencing of cancer-relevant genes. Three out of 57 patients (5.3%) harbored confirmed germline mutations that were likely causal, in NBN, ETV6, and FLT3, with an additional six patients (10.5%) harboring putative predisposing mutations that were rare in unselected individuals (<0.01% allele frequency in the Exome Aggregation Consortium, ExAC) and predicted functional (scaled CADD score ≥ 20) in known or potential ALL predisposition genes (SH2B3, CREBBP, PMS2, MLL, ABL1, and MYH9). Three additional patients carried rare and predicted damaging germline mutations in GAB2, a known activator of the ERK/MAPK and PI3K/AKT pathways and binding partner of PTPN11-encoded SHP2. The frequency of rare and predicted functional germline GAB2 mutations was significantly higher in our patients (2.6%) than in ExAC (0.28%, P = 4.4 × 10-3 ), an observation that was replicated in ALL patients from the TARGET project (P = .034). We cloned patient GAB2 mutations and expressed mutant proteins in HEK293 cells and found that frameshift mutation P621fs led to reduced SHP2 binding and ERK1/2 phosphorylation but significantly increased AKT phosphorylation, suggesting possible RAS-independent leukemogenic effects. Our results support a significant contribution of rare, high penetrance germline mutations to HD-ALL etiology, and pinpoint GAB2 as a putative novel ALL predisposition gene.

Abstract P4-03-01: Pathway level complementarity of germline and somatic events in breast cancer

Abstract Background: Progression from a normal cell state to cancer requires multiple genomic hits in key regulatory pathways. In the case of hereditary cancer syndromes, some of these hits occur in the germline, but additional somatic mutations are required for malignant transformation. We hypothesize that this paradigm could be extended to sporadic cancers as well. What somatic mutation function as a cancer driver event may be determined by the constellation of germline variants a person is born with. We propose that even rare, non-recurrent, high functional impact germline variants in genes involved in cancer-related pathways could influence the biological impact of somatic mutations in other cancer-related genes. The goal of the current analysis was to examine associations between pathway alterations caused by high functional impact germline variants or somatic mutations in the “hallmarks of cancer” pathways in breast cancer. Methods: We obtained germline DNA sequencing and copy number variation (CNV) data from the breast cancer TCGA cohort. After population clustering with the HapMap cohort, we selected a homogeneous group of 796 patients of Western European ancestry and downloaded the matching somatic mutations (SNVs and INDELs) that were available for 750 cases, that comprise the current study population. Germline CNVs were classified as recurrent or rare losses or gains. Potentially pathogenic germline variants (SNPs) were obtained from the PanCancer Altas project. All germline or somatic mutations were mapped at the gene level to the 50 Cancer Hallmarks pathway collection. We designated a pathway mutated if at least 1 gene had a germline or a somatic mutation. Complementarity between pathway alterations by germline and somatic events were evaluated using the Fisher exact test adjusted for multiple comparisons. Results: At the germline level, 2,057 genes were affected by CNVs (mean 30, range 3-151 genes/patient), and a total of 43 genes carried germline pathogenic SNPs that affected 13.8% of the patients. At the somatic level, we detected 40,881 high functional impact mutations (mean 54.3, range 1-3889 mutations/patient) in 13,080 genes (mean 50.8, range 1-3166 genes/patient). The 50 Cancer Hallmark pathways contained 4386 genes (mean 146.5, range 32-200 genes/pathway), and were mutated in the majority of the patients (85% germline, 93% somatic). Several pathways, such as HEME_METABOLISM, INTERFERON_ALPHA_RESPONSE, and KRAS_SIGNALING, were frequently affected by germline alterations, while the somatic mutations were most frequently involved in the COMPLEMENT, E2F_TARGET, and UV_RESPONSE_UP. Interaction analysis revealed co-occurrence between MYC_TARGETS_V1 (germline) and UV_RESPONSE_DN (somatic) or MTORC1_SINGALING (somatic) (p&amp;lt;0.01), and TNFA_SIGNALING_VIA_NFKB (germline) and IL6_JAK_STAT3_SIGNALING (germline) with E2F_TARGETS (somatic) (p&amp;lt;0.01). We also observed an exclusive relationship between germline alterations in BILE_ACID_METABOLISM and somatic mutations in COMPLEMENT pathway (p&amp;lt;0.01). Conclusions: Our results highlight the importance of pathway-level analysis of germline alterations in breast cancer, which might help to understand the interrelationship between germline and somatic alterations in breast cancer. Citation Format: Qing T, Marczyk M, Wali V, Gunasekharan V, Patwardhan G, Pusztai L, Hatzis C. Pathway level complementarity of germline and somatic events in 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 P4-03-01.

Lymphotoxin alpha functional germline genetic variant: A future prognostic factor in colorectal cancer?

603 Background: Lymphotoxin alpha (LTa) is a proinflammatory cytokine expressed by inflammatory cells with a role in the regulation of tumor microenvironment (TM). A putatively functional genetic polymorphism in LTA, at locus +80 (Thr26Asn, rs1041981), has been associated with altered expression of LTa. Here, we sought to evaluate whether this polymorphism associates with two main endpoints (progression-free survival (PFS) and overall survival(OS)) in colorectal cancer (CRC). Methods: This retrospective cohort study was conducted in 166 CRC patients from a single tertiary hospital. Whole blood was used to isolate genomic DNA. Genotyping of LTA + 80 C &gt; A was performed through real time-PCR allelic discrimination using specific Taqman probes, and confirmed by sequencing. Retrospective data and long-term outcomes were reviewed. Age and gender-adjusted logistic regression analyses were undertaken. Analyses were conducted after stratification by baseline lymphocyte count (LC) (LC &lt; 1x103/µL vs. &gt; 1x103/µL). Kaplan-Meier curves with Log-Rank test were used. Subsequent multivariate Cox regression proportional hazards models were calculated (P for retention &gt; 0.1). Results: Participants’ median age was 65.9 (IR, 57.5-74.3) years, the majority were males (63%), and 58% with colon cancer. At diagnosis, 45,2% were stage III and 18,1% stage IV. The median follow up time was approximately four years (IQR, 25.5-67.0 months). We found a significant association in carriers of the A-allele to have lower LC on linear trend analysis (P for trend = 0.013). Multivariate comparisons between LTA genotypes of additive model showed an independent protective effect for heterozygous compared with C-homozygous in the association with disease progression (HR = 0.5, 95 CI = 0.3-0.97, P = 0.041), only in subjects with baseline LC &gt;1x103/µL. In this group, a significant independent protective effect for all-cause mortality was observed in A-carriers (HR = 0.4, 95 CI = 0.1-0.97, P = 0.042). Conclusions: This LTA genetic variant in subjects with baseline LC &gt; 1x103/µL is associated with PFS and OS in CRC. The understanding of the impact of this polymorphisms on the evolution of the disease can bring us new information on TM regulation.