Inactivating Germline Mutations Research Articles

Clinical and molecular characterization of parathyroid carcinoma in multiple endocrine neoplasia type 1.

Nineteen cases of parathyroid carcinoma in patients with multiple endocrine neoplasia type 1 have been reported in the literature, of which 11 carry an inactivating germline mutation in the MEN1 gene. Somatic genetic abnormalities in these parathyroid carcinomas have never been detected. In this paper, we aimed to describe the clinical and molecular characterization of a parathyroid carcinoma identified in a patient with MEN1. A 60-year-old man was diagnosed with primary hyperparathyroidism during the postoperative period of lung carcinoid surgery. Serum calcium and parathyroid hormone levels were 15.0 mg/dL (8.4-10.2) and 472 pg/mL (12-65), respectively. The patient underwent parathyroid surgery, and histological findings were consistent with parathyroid carcinoma. Analysis of the MEN1 gene by next-generation sequencing (NGS) identified a novel germline heterozygous nonsense pathogenic variant (c.978C>A; p.(Tyr326*)), predicted to encode a truncated protein. Genetic analysis of the parathyroid carcinoma revealed a c.307del, p.(Leu103Cysfs*16) frameshift truncating somatic MEN1 variant in the MEN1 gene, which is consistent with MEN1 tumor-suppressor role, confirming its involvement in parathyroid carcinoma etiology. Genetic analysis of CDC73, GCM2, TP53, RB1, AKT1, MTOR, PIK3CA and CCND1 genes in the parathyroid carcinoma DNA did not detect any somatic mutations. To our knowledge, this is the first report of a PC case presenting both germline (first-hit) and somatic (second-hit) inactivation of the MEN1 gene.

FOXA2 controls the anti-oxidant response in FH-deficient cells

Hereditary leiomyomatosis and renal cell cancer (HLRCC) is a cancer syndrome caused by inactivating germline mutations in fumarate hydratase (FH) and subsequent accumulation of fumarate. Fumarate accumulation leads to profound epigenetic changes and the activation of an anti-oxidant response via nuclear translocation of the transcription factor NRF2. The extent to which chromatin remodeling shapes this anti-oxidant response is currently unknown. Here, we explored the effects of FH loss on the chromatin landscape to identify transcription factor networks involved in the remodeled chromatin landscape of FH-deficient cells. We identify FOXA2 as a key transcription factor that regulates anti-oxidant response genes and subsequent metabolic rewiring cooperating without direct interaction with the anti-oxidant regulator NRF2. The identification of FOXA2 as an anti-oxidant regulator provides additional insights into the molecular mechanisms behind cell responses to fumarate accumulation and potentially provides further avenues for therapeutic intervention for HLRCC.

Belzutifan treatment of Von Hippel-Lindau (VHL) related central nervous system (CNS) hemangioblastomas (HBs): A single institution experience.

2078 Background: Patients with inactivating germline mutations in the VHL gene develop CNS (brain and/or spine) HBs and/or renal cancers, pheochromocytomas and pancreatic neuroendocrine tumors. The oral HIF2a inhibitor belzutifan has been approved by FDA for the treatment of VHL-related HBs. We present here data on a cohort of VHL patients with CNS HBs treated with belzutifan in a single institution. Methods: Adult VHL patients, with radiologically documented CNS (brain and/or spine) HBs that displayed documented growth within the last 6 months prior to therapy, were treated with an initial dose of 120 mg belzutifan orally per day. Target lesions included HBs > 0.4cm long in one maximal cross-sectional diameter. Lesions were imaged by MRI at 1.5, 3, 6 months after initiation of treatment and at 6-month intervals thereafter. Solid enhancing lesions, associated cysts and peritumoral edema were recorded and quantified. Tumor sizes were evaluated by RECIST 1.1 criteria and volumetric analysis. All patients were evaluated and treated in the Hemangioblastoma Center and the VHL Clinic of the Massachusetts General Hospital Cancer Center. Results: At the time of analysis, 9 females and ten 10 male VHL patients (n=19) have been treated. Median age at treatment initiation was 36 yo (range 19-59). Median follow up is 12 months (range 1-19.5 months). Two patients were not yet evaluable for response. Of 17 evaluable patients, 8 had a PR (ORR 47%; 95% CI, 34-60), 8 had SD and 1 patient had progression (PD, 5.8%). Two patients had dose reduction to 80 mg/d because of anemia. No patient had grade 3 or greater toxicity and no patient experienced a CNS related toxicity during treatment. Volumetric analysis of solid and cystic components of the lesions, VHL germline mutations and other correlates of response to belzutifan will be presented. Conclusions: Real world data collected at a single institution confirm the high response rate of both solid and cystic components of CNS HBs to the FDA approved HIF2a inhibitor, belzutifan. Belzutifan was well tolerated. Further prospective controlled studies addressing the optimal dose, schedule and duration of treatment of HBs with belzutifan are required.

Strong adaptive immunity in humans with inherited CD4 deficiency

Abstract Since the early 1970s when the T cell receptor was first characterized, the role of human CD4 in adaptative immunity has been extensively studied, especially in the context of HIV infection and inborn error of immunity (e.g. HLA class II deficiency). Nonetheless, it was only recently (2019, 2021) that patients with inactivating germline mutations in CD4has been described. Herein, we present five novel patients from three unrelated kindred with bi-allelic rare variants in CD4. Consistent with previous studies, patients showed a broad spectrum of clinical infectious susceptibility which was rather mild given their lack of detectable CD4 +T cells in peripheral blood mononuclear cells (PBMCs). Despite an almost unremarkable immunophenotype, patient’s PBMCs were characterized by the expansion of an enigmatic CD4 −CD8 −(DN) TCRαβ +T cells population which retained some functional characteristic of typical CD4 +T cells. We observed that the patient’s DN cells transcriptionally (Sc-RNAseq) and functionally (cytokine production/secretion) were comparable to that of healthy donor CD8 −T cells. Interestingly, using cutting-edge long-read sc-RNAseq technology we revealed that patient’s DN cells expressed normal TCR repertoires, and paired TCRαβ sequences comparable to healthy donor CD4 +T cells. Furthermore, via biochemical studies we identified a CD4alternative transcript expressed in patient’s PBMCs (also detected in healthy donor cells) leading to the surface expression of an unreported CD4 shorter isoform which is not detectable with conventional CD4 antibodies. To conclude, our study not only characterizes novel CD4-deficient patients, but also reveals alternative CD4 isoform expression and its compensatory role in immunity. AAI Careers in Immunology Fellowship 2022 (RG222573)

PMON115 Long term follow-up of patient with gigantism harboring an exon 2 deletion in the AIP gene

Abstract Introduction Pituitary gigantism is a rare endocrinopathy that has been linked to inactivating germline mutations in AIP gene with a prevalence of 30%. AIP is a tumor suppressor gene associated with high predisposition to pituitary adenoma. Thus, the genetic screening of AIP mutations has been recommended to cases with sporadic young-onset pituitary adenoma. Even with a phenotype suggesting gigantism the diagnosis could be delayed, making the treatment more complex, due the large pituitary tumor. Here we describe a giant patient with deletion of exon 2 of the AIP gene detected by Multiplex Ligation-dependent Probe Amplification assay (MLPA) 33 years after the diagnosis. Material and Methods In 1988, a 13-year-old afro-descendent boy with no history of familial pituitary adenoma, presented with seizures and tall stature. On exam he showed signs of gigantism and hypopituitarism: height 2.05 m (SD: + 7), target height was 1.65 (SD: -1), weight 75 kg (SD: + 3.2), no signs of puberty and impaired vision field. Basal GH was > 40 ng/mL, IGF-1: > 1200 ng/mL (ULN: +4). MRI revealed an invasive macroadenoma (Knosp IV). He underwent pituitary surgery twice with an adenoma GH/PRL positive with no remission. He did not respond to the treatment with somatostatin receptor analogue presenting remission only after radiotherapy, developing permanent deficiency of ACTH/TSH/LH/FSH/GH and diabetes insipidus. Peripheral blood was collected to genetic analysis in 2021. Results The genetic analysis supported by Sanger sequencing resulted negative to pathogenic germline variants in intron-exon frontiers and coding areas of the AIP and MEN1 genes. Thus, MLPA was performed using the SALSA MLPA kit P244 designed to detect large deletions or amplifications in AIP, CDKN1B and MEN1 genes (MRC-Holland, Amsterdam, The Netherlands). Once the exon 2 heterozygous deletion from the AIP gene was found via MLPA the confirmation was carried out through long-range PCR covering full open reading frame of the AIP gene. By agarose gel electrophoresis, the presence of two bands of different sizes confirmed this deletion. Discussion More than 130 AIP mutations have been described over the last decade and most of them, 70% generate truncated proteins (including insertions/deletions). However, gross AIP deletions were exceptionally reported so far (13 cases only: 11 had gigantism or acromegaly). Despite rarity, the present case reinforces the importance of investigate large AIP deletions, especially in gigantism. Cases harboring AIP mutations are associated with more aggressive tumors, lesser response to somatostatin receptor analogues needing, frequently, of an extensive multidisciplinary approach. It was also suggested that cases harboring truncated AIP mutations may develop pituitary adenoma in younger age than patients with non-truncated mutations. Thus, the characterization of genotype could help to refine making-decision on management of this complex disorder in an earlier stage avoiding multimodal treatment. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

OR12-6 Rocking Around the Cortex and Medulla

Abstract Introduction Pituitary gigantism is a rare endocrinopathy that has been linked to inactivating germline mutations in AIP gene with a prevalence of 30%. AIP is a tumor suppressor gene associated with high predisposition to pituitary adenoma. Thus, the genetic screening of AIP mutations has been recommended to cases with sporadic young-onset pituitary adenoma. Even with a phenotype suggesting gigantism the diagnosis could be delayed, making the treatment more complex, due the large pituitary tumor. Here we describe a giant patient with deletion of exon 2 of the AIP gene detected by Multiplex Ligation-dependent Probe Amplification assay (MLPA) 33 years after the diagnosis. Material and Methods In 1988, a 13-year-old afro-descendent boy with no history of familial pituitary adenoma, presented with seizures and tall stature. On exam he showed signs of gigantism and hypopituitarism: height 2. 05 m (SD: + 7), target height was 1.65 (SD: -1), weight 75 kg (SD: + 3.2), no signs of puberty and impaired vision field. Basal GH was > 40 ng/mL, IGF-1: > 1200 ng/mL (ULN: +4). MRI revealed an invasive macroadenoma (Knosp IV). He underwent pituitary surgery twice with an adenoma GH/PRL positive with no remission. He did not respond to the treatment with somatostatin receptor analogue presenting remission only after radiotherapy, developing permanent deficiency of ACTH/TSH/LH/FSH/GH and diabetes insipidus. Peripheral blood was collected to genetic analysis in 2021. Results The genetic analysis supported by Sanger sequencing resulted negative to pathogenic germline variants in intron-exon frontiers and coding areas of the AIP and MEN1 genes. Thus, MLPA was performed using the SALSA MLPA kit P244 designed to detect large deletions or amplifications in AIP, CDKN1B and MEN1 genes (MRC-Holland, Amsterdam, The Netherlands). Once the exon 2 heterozygous deletion from the AIP gene was found via MLPA the confirmation was carried out through long-range PCR covering full open reading frame of the AIP gene. By agarose gel electrophoresis, the presence of two bands of different sizes confirmed this deletion. Discussion More than 130 AIP mutations have been described over the last decade and most of them, 70% generate truncated proteins (including insertions/deletions). However, gross AIP deletions were exceptionally reported so far (13 cases only: 11 had gigantism or acromegaly). Despite rarity, the present case reinforces the importance of investigate large AIP deletions, especially in gigantism. Cases harboring AIP mutations are associated with more aggressive tumors, lesser response to somatostatin receptor analogues needing, frequently, of an extensive multidisciplinary approach. It was also suggested that cases harboring truncated AIP mutations may develop pituitary adenoma in younger age than patients with non-truncated mutations. Thus, the characterization of genotype could help to refine making-decision on management of this complex disorder in an earlier stage avoiding multimodal treatment. Presentation: Sunday, June 12, 2022 11:00 a.m. - 12:30 p.m.

A two-generation hyperparathyroidism-jaw tumor (HPT-JT) syndrome family: clinical presentations, pathological characteristics and genetic analysis: a case report

BackgroundHyperparathyroidism-Jaw Tumor (HPT-JT) is caused by inactivating germline mutations of CDC73. This hereditary disease can present with a range of symptoms. Jaw ossifying fibroma (OF) is one of the most important clinical presentations, affecting 30% of HPT-JT patients. However, OF is easily confused with other fibro-osseous lesions (FOLs) of the jaw. The correct diagnosis of HPT-JT is a real challenge and must be confirmed by genetic testing.Case presentationA female proband and her father suffered from multiple and recurrent FOLs in the jaw. Considering well demarcated margin and heterogeneous calcified substance lying in a variable density of fibrous stroma, we reached the diagnosis of jaw OF through radiologic and microscopic analyses. Additionally, the proband presented with chronic anemia resulting from menorrhagia, as well as renal mixed epithelial and stromal tumor (MEST). Two patients both presented with no evidence of Hyperparathyroidism (HPT). A germline start codon mutation (c.1A > G) of CDC73 was identified in them. Copy number loss at the CDC73 gene locus was verified in the jaw tumor sample of the proband.ConclusionRegardless of whether HPT manifestations are present, patients with heritable jaw OF may be at risk for HPT-JT. Genetic testing should be adopted to confirm the diagnosis. Early recognition of HPT-JT helps to better develop tailored treatment plans and surveillance programs.

Abstract 5898: Bone morphogenic protein receptor 2 (BMPR2) as a potential germline driver in Juvenile Polyposis Syndrome (JPS)

Abstract Summary: Juvenile Polyposis Syndrome is a pediatric cancer predisposition syndrome for which approximately half of patients do not have a known germline driver; we propose BMPR2 as a possible germline driver of disease in mutation-negative JPS. Background: Juvenile Polyposis Syndrome (JPS) is a cancer predisposition syndrome characterized in some cases by inactivating germline mutations in BMPR1A or SMAD4. However, in 40-60% of patients the germline driver is unknown. Methods: Through whole exome sequencing, an individual with high polyp burden and negative genetic testing for variants in SMAD4 and BMPR1A was found to have a potentially inactivating germline variant in BMPR2. Under an IRB-approved protocol, patient-derived, three-dimensional organoids were established from adjacent colon and polyp tissue of this individual, as well as an individual with a BMPR1A deletion and age- and sex-matched controls. Proliferation, metabolic activity, and protein expression of each line were measured by Western blot, Ki67 staining, EdU labelling, cell titer glo (CTG) assay. Results: Distinct phenotypic differences are evident between colonoids from an individual with a BMPR1A deletion and both the colon and polyp BMPR2 variant colonoids, such as increased crypt budding and Ki67 staining. CTG assay data indicate higher metabolic activity in BMPR2 variant colonoids in comparison to normal controls (p= 0.0104.) Through Western blot analysis, both BMPR2 colon and polyp colonoids showed decreased SMAD4 expression and phosphorylation. Conclusions: These data demonstrate that clear phenotypic differences exist between colonoid lines established from normal controls, individuals with known JPS predisposition genes, and a novel candidate driver of disease, BMPR2. Proliferation and protein expression data suggest that both known and candidate genotypes are consistent with a hyperproliferative phenotype. In vitro data support BMPR2 as a candidate germline driver of the JPS phenotype, and additional study is ongoing regarding downstream pathway regulation in colonoids with a BMPR2 variant. Citation Format: Suzanne P. MacFarland, Bridgid Greed, Michael H. Xie, Garrett M. Brodeur, Zvi Cramer, Maiah H. Dent, Melani M. Duvall, Kathryn E. Hamilton, James Howe, Tatiana Karakasheva, Petar Mamula, Christopher Lengner. Bone morphogenic protein receptor 2 (BMPR2) as a potential germline driver in Juvenile Polyposis Syndrome (JPS) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5898.

Molecular and immune landscape of FH-mutated cancers.

3125 Background: Fumarate Hydratase (FH) encodes an essential enzyme in the TCA cycle. Inactivating germline mutations in FH lead to hereditary leiomyomatosis and renal cell cancer syndrome with risk of development of certain cancers. Sporadic FH mutations have been described in different cancers but implications of somatic mutations on cancer outcomes and survival are not well described. Here, we characterize the molecular landscape of FH-mutant cancers. Methods: Tumors analyzed using NGS (NextSeq, 592 genes; NovaSeq, WES), IHC, and WTS (NovaSeq) (Caris Life Sciences, Phoenix, AZ). PD-L1 tested by 22c3, 28-8 (Agilent) and SP-142 (Spring Biosciences) IHC (>1%). MSI tested by FA, IHC, and NGS. TMB measured by totaling somatic mutations per tumor (TMB-h > 10 mutations/MB). Real-world overall survival was extracted from insurance claims data and calculated from first treatment to last contact using K-M survival curves for molecularly defined cohorts. Statistical significance was determined using chi-square and Wilcoxon rank-sum test, adjusted for multiple comparisons (q<0.05). Results: 3239 FH mutations were seen in 45 tumor types in 3149 FH-mutated tumors. NSCLC, colorectal and endometrial cancers harbored the most mutations. There were 839 pathogenic (P) or likely pathogenic (LP) and 2400 variants of unknown significance (VUS). Some tumors had multiple mutations. The most common mutations: R233H (P; 37), K477dup (LP; 555), and A41V (VUS; 70). VUS had increased TMB-H (40.4% vs 29.8%, q=0.004) and CREBBP mutations (5.1% vs 1.6%, q=0.012) compared to P+LP. A41V-mt tumors had significantly lower TMB-H than other VUS (8.8% vs 41.5%, q=0.002) and lower MSI-H (3.13% vs 3.69% vs 29.4%, q=0.003) and DICER1, PRKDC, FBXW7 mutations (q<0.05) compared to K477dup and R233. The A41V-mt patients had worse survival compared to patients with P+LP (HR: 1.4, 95% CI: 1.0-2.0, p = 0.049) and a trend toward worse survival compared to K477dup and R233H. In patients treated with chemotherapy, A41 was associated with worse survival compared to P+LP (HR: 4.6, 95% CI: 2.0-10.3, p<0.0001) and compared to K477dup and R233 (p<0.01). There was a trend towards worse survival after IO of A41-mt compared to P+LP (HR: 1.99, 95% CI: 0.88-4.5, p = 0.093). Conclusions: FH alterations are found in multiple cancers. A41V was the most common VUS mutation and is associated with a distinct molecular profile compared to K477dup-mt and R233-mt tumors; it was associated with worse survival in all-comers and after chemotherapy compared to P+LP mutations. This highlights the significance of this mutation and the need for further investigation into how this specific and other FH mutations contribute to cancer progression and treatment outcomes.

BRCA1: An Endocrine and Metabolic Regulator.

The breast and ovarian cancer susceptibility gene (BRCA1) is a tumor suppressor whose mutation has been associated with the development of breast, ovarian and, probably, other malignancies at young ages. The BRCA1 gene product participates in multiple biological pathways including the DNA damage response, transcriptional control, cell growth and apoptosis. Inactivating germline mutations of the BRCA1 gene can be detected in a substantial portion of families with inherited breast and/or ovarian cancer. While the genomic and cancer-related actions of BRCA1 have been extensively investigated, not much information exists regarding the cellular and circulating factors involved in regulation of BRCA1 expression and action. The present review article dissects the emerging role of BRCA1 as an important regulator of various endocrine and metabolic axes. Experimental and clinical evidence links BRCA1 with a number of peptide and steroid hormones. Furthermore, comprehensive analyses identified complex interactions between the insulin/insulin-like growth factor-1 (IGF1) signaling axis and BRCA1. The correlation between metabolic disorders, including diabetes and the metabolic syndrome, and BRCA1 mutations, are discussed in this article.

Sporadic superficial angiomyxomas demonstrate loss of PRKAR1A expression.

Superficial angiomyxomas are cutaneous mesenchymal tumours that typically present clinically as slow-growing, solitary, asymptomatic nodules that can occur at any age. Histopathologically, these dermal and subcutaneous tumours are characterized by abundant myxoid stroma, numerous thin-walled and often arbourising blood vessels, and spindled to stellate fibroblast-like cells. While usually sporadic, superficial angiomyxomas can occasionally be associated with Carney complex (CNC), an autosomal dominant disorder characterized by inactivating germline mutations in the 1-alpha regulatory subunit of protein kinase A (PRKAR1A) and various clinical manifestations, including cardiac myxomas, facial lentigines, epithelioid blue naevi, endocrinopathies and psammomatous melanotic schwannomas. In this study, we sought to characterize the presence or absence of PRKAR1A expression by immunohistochemistry (IHC) in sporadic superficial angiomyxomas based on our observations in an index case. In total, PRKAR1A immunohistochemical expression was determined in 15 sporadic superficial angiomyxoma cases retrieved from the surgical pathology archives. IHC demonstrated that the lesional cells in 12 cases (80%) were non-reactive to antibodies against PRKAR1A. This study provides evidence in support of a role for PRKAR1A in the development of clinically non-syndromic superficial angiomyxomas. Together with previous studies, this report demonstrates that PRKAR1A may play an important role in the development of a variety of myxomatous mesenchymal tumours.

Molecular and immune landscape of FH-mutated kidney cancer.

382 Background: Hereditary leiomyomatosis and renal cell cancer (HLRCC) syndrome is caused by inactivating germline mutations in fumarate hydratase ( FH), predisposing individuals to development of certain cancers. Sporadic FH mutations have been described in different types of cancers, including kidney cancers, but the implications of somatic mutations are not well described. Here, we characterize the molecular landscape of kidney tumors with FH mutations. Methods: Tumors were analyzed using next generation sequencing of DNA (NextSeq, 592 genes and NovaSeq, WES) and RNA (NovaSeq). Immune cell fraction was estimated by immune deconvolution (Quantiseq). Significance was determined by chi-square and Wilcoxon rank sum test and adjusted for multiple comparisons (q-value <0.05). Results: Of 1956 kidney tumors, 31 had somatic pathogenic or likely pathogenic (P+LP; 1.58%) and 21 had variant of unknown significance (VUS; 1.07%) mutations in FH. Among the most commonly co-mutated genes, VHL (29.03% vs 38.1% vs 55.2%) and PBRM1 (9.68% vs 20% vs 29.8%) were less frequently mutated in P+LP compared to VUS and WT tumors; while NF2 (22.6% vs 5% vs 5.65%) was more frequently mutated in P+LP tumors compared to the others. In P+LP tumors, the HIPPO pathway (22.6% vs 4.76% vs 5.62%) was more frequently altered while the chromatin remodeling pathway (25.8% vs 28.6% vs 51.1%) was less frequently altered compared to VUS or WT tumors. P+LP tumors showed decreased NK cell infiltration (q=0.01) compared to VUS and WT tumors. Additionally, there was a trend towards increased CD8+ T cells and CTLA4 and PDCD1 expression in P+LP tumors compared to VUS but not WT tumors. Of the 1,956 kidney tumors, 315 were of clear cell renal cell carcinoma (ccRCC) histology. P+LP (n=4) ccRCC tumors showed a trend towards higher expression of immune checkpoint genes CTLA4 and IDO1 compared to VUS tumors (n=5). VHL expression was higher in P+LP ccRCC compared to VUS ccRCC tumors. P+LP ccRCC tumors showed a trend toward increased CD4+ (2.59% vs 0%) and CD8+ (2.14% vs 0%) T cells as well as T cell inflammation (25% vs 0%) and median Interferon score compared to VUS ccRCC tumors. Conclusions: P+LP FH mutated kidney tumors may have a different mutational and immune landscape than VUS FH mutated and WT tumors. Despite the small sample size, our study highlights potential therapeutic implications that will require further study.[Table: see text]

NSD1 mutations deregulate transcription and DNA methylation of bivalent developmental genes in Sotos syndrome.

Sotos syndrome (SS), the most common overgrowth with intellectual disability (OGID) disorder, is caused by inactivating germline mutations of NSD1, which encodes a histone H3 lysine 36 methyltransferase. To understand how NSD1 inactivation deregulates transcription and DNA methylation (DNAm), and to explore how these abnormalities affect human development, we profiled transcription and DNAm in SS patients and healthy control individuals. We identified a transcriptional signature that distinguishes individuals with SS from controls and was also deregulated in NSD1-mutated cancers. Most abnormally expressed genes displayed reduced expression in SS; these downregulated genes consisted mostly of bivalent genes and were enriched for regulators of development and neural synapse function. DNA hypomethylation was strongly enriched within promoters of transcriptionally deregulated genes: overexpressed genes displayed hypomethylation at their transcription start sites while underexpressed genes featured hypomethylation at polycomb binding sites within their promoter CpG island shores. SS patients featured accelerated molecular aging at the levels of both transcription and DNAm. Overall, these findings indicate that NSD1-deposited H3K36 methylation regulates transcription by directing promoter DNA methylation, partially by repressing polycomb repressive complex 2 (PRC2) activity. These findings could explain the phenotypic similarity of SS to OGID disorders that are caused by mutations in PRC2 complex-encoding genes.

E-Cadherin-Deficient Epithelial Cells Are Sensitive to HDAC Inhibitors.

Simple SummaryInactivating mutations in the CDH1 gene cause the cancer syndrome hereditary diffuse gastric cancer and are also frequent in sporadic diffuse gastric and lobular breast cancers. This research aimed to test whether cancers with CDH1 mutations have heightened sensitivity to histone deacetylase (HDAC) inhibitors. The impact of these drugs was tested on several gastric and breast preclinical models with and without CDH1 mutations. One HDAC inhibitor, entinostat, showed a strong inhibitory effect on each of the models with CDH1 mutations. This study highlighted the potential beneficial impact of entinostat for the chemoprevention and/or treatment of gastric and breast cancers carrying CDH1 mutations.Inactivating germline mutations in the CDH1 gene (encoding the E-cadherin protein) are the genetic hallmark of hereditary diffuse gastric cancer (HDGC), and somatic CDH1 mutations are an early event in the development of sporadic diffuse gastric cancer (DGC) and lobular breast cancer (LBC). In this study, histone deacetylase (HDAC) inhibitors were tested for their ability to preferentially inhibit the growth of human cell lines (MCF10A and NCI-N87) and murine organoids lacking CDH1 expression. CDH1−/− breast and gastric cells were more sensitive to the pan-HDAC inhibitors entinostat, pracinostat, mocetinostat and vorinostat than wild-type cells, with an elevated growth inhibition that was, in part, attributable to increased apoptosis. CDH1-null cells were also sensitive to more class-specific HDAC inhibitors, but compared to the pan-inhibitors, these effects were less robust to genetic background. Increased sensitivity to entinostat was also observed in gastric organoids with both Cdh1 and Tp53 deletions. However, the deletion of Tp53 largely abrogated the sensitivity of the Cdh1-null organoids to pracinostat and mocetinostat. Finally, entinostat enhanced Cdh1 expression in heterozygous Cdh1+/− murine organoids. In conclusion, entinostat is a promising drug for the chemoprevention and/or treatment of HDGC and may also be beneficial for the treatment of sporadic CDH1-deficient cancers.

Asbestos-induced chronic inflammation in malignant pleural mesothelioma and related therapeutic approaches-a narrative review.

Objective:The aim of this review is addressing the mechanisms of asbestos carcinogenesis, including chronic inflammation and autophagy-mediated cell survival, and propose potential innovative therapeutic targets to prevent mesothelioma development or improve drug efficacy by reducing inflammation and autophagy.Background:Diffuse malignant pleural mesothelioma is an aggressive cancer predominantly related to chronic inflammation caused by asbestos exposure. Millions of individuals have been exposed to asbestos or to other carcinogenic mineral fibers occupationally or environmentally, resulting in an increased risk of developing mesothelioma. Overall patient survival rates are notably low (about 8–14 months from the time of diagnosis) and mesothelioma is resistant to existing therapies. Additionally, individuals carrying inactivating germline mutations in the BRCA-associated protein 1 (BAP1) gene and other genes are predisposed to developing cancers, prevalently mesothelioma. Their risk of developing mesothelioma further increases upon exposure to asbestos. Recent studies have revealed the mechanisms and the role of inflammation in asbestos carcinogenesis. Biomarkers for asbestos exposure and malignant mesothelioma have also been identified. These findings are leading to the development of novel therapeutic approaches to prevent or delay the growth of mesothelioma.Methods:Review of full length manuscripts published in English from January 1980 to February 2021 gathered from PubMed.gov from the National Center of Biotechnology Information and the National Library of Medicine were used to inform this review.Conclusion:Key regulators of chronic inflammation mediate asbestos-driven mesothelial cell transformation and survival through autophagic pathways. Recent studies have elucidated some of the key mechanisms involved in asbestos-induced chronic inflammation, which are largely driven by extracellular high mobility group box 1 (HMGB1). Upon asbestos exposure, mesothelial cells release HMGB1 from the nucleus to the cytoplasm and extracellular space, where HMGB1 initiates an inflammatory response. HMGB1 translocation and release also activates autophagy and other pro-survival mechanisms, which promotes mesothelioma development. HMGB1 is currently being investigated as a biomarker to detect asbestos exposure and to detect mesothelioma development in its early stage when therapy is more effective. In parallel, several approaches inhibiting HMGB1 activities have been studied and have shown promising results. Moreover, additional cytokines, such as IL-1β and TNF-α are being targeted to interfere with the inflammatory process that drives mesothelioma growth. Developing early detection methods and novel therapeutic strategies is crucial to prolong overall survival of patients with mesothelioma. Novel therapies targeting regulators of asbestos-induced inflammation to reduce mesothelioma growth may lead to clinical advancements to benefit patients with mesothelioma.

CDH1 Gene Mutation Hereditary Diffuse Gastric Cancer Outcomes: Analysis of a Large Cohort, Systematic Review of Endoscopic Surveillance, and Secondary Cancer Risk Postulation.

Simple SummarySome patients carry a mutated copy of the CDH1 gene that can lead to a very rare form of hereditary gastric cancer called signet-ring cell adenocarcinoma (SRCC). SRCCs rarely form visible tumors prior to spreading. Hence, patients are recommended to have prophylactic gastrectomies at a young age. Many patients wish to avoid surgery and thus have regular checks with upper endoscopy with biopsies to rule out cancer. Further, these patients may also be at risk of other cancers beyond the already known breast cancer risks, but this is not known. In this study, we show that despite systematic biopsy protocols, many early cancers might be missed on endoscopy. Therefore, patients should not rely on endoscopy to delay surgery. These patients may also be at increased risk of colorectal SRCC, which has very poor survival outcomes. To confirm this, we need a central database that captures outcomes for this patient population.Hereditary diffuse gastric cancer (HDGC) is a rare signet-ring cell adenocarcinoma (SRCC) linked to CDH1 (E-cadherin) inactivating germline mutations, and increasingly other gene mutations. Female CDH1 mutation carriers have additional risk of lobular breast cancer. Risk management includes prophylactic total gastrectomy (PTG). The utility of endoscopic surveillance is unclear, as early disease lacks macroscopic lesions. The current systematic biopsy protocols have unknown efficacy, and other secondary cancer risks are postulated. We conducted a retrospective study of consecutive asymptomatic HDGC patients undergoing PTG, detailing endoscopic, pathologic, and outcome results. A systematic review compared endoscopic biopsy foci detection via random sampling versus Cambridge Protocol against PTG findings. A population-level secondary-cancer-risk postulation among sporadic gastric SRCC patients was completed using the Surveillance, Epidemiology, and End Results database. Of 97 patients, 67 underwent PTG, with 25% having foci detection on random endoscopic biopsy despite 75% having foci on final pathology. There was no improvement in the endoscopic detection rate by Cambridge Protocol. The postulated hazard ratio among sporadic gastric SRCC patients for a secondary colorectal SRCC was three-fold higher, relative to conventional adenocarcinoma patients. Overall, HDGC patients should not rely on endoscopic surveillance to delay PTG, and may have secondary SRCC risks. A definitive determination of actual risk requires collaborative patient outcome data banking.

Carney Triad, Carney-Stratakis Syndrome, 3PAS and Other Tumors Due to SDH Deficiency.

Succinate dehydrogenase (SDH) is a key respiratory enzyme that links Krebs cycle and electron transport chain and is comprised of four subunits SDHA, SDHB, SDHC and SDHD. All SDH-deficient tumors are caused by or secondary to loss of SDH activity. As many as half of the familial cases of paragangliomas (PGLs) and pheochromocytomas (PHEOs) are due to mutations of the SDHx subunits. Gastrointestinal stromal tumors (GISTs) associated with SDH deficiency are negative for KIT/PDGFRA mutations and present with distinctive clinical features such as early onset (usually childhood or adolescence) and almost exclusively gastric location. SDH-deficient GISTs may be part of distinct clinical syndromes, Carney-Stratakis syndrome (CSS) or dyad and Carney triad (CT). CSS is also known as the dyad of GIST and PGL; it affects both genders equally and is inherited in an autosomal dominant manner with incomplete penetrance. CT is a very rare disease; PGL, GIST and pulmonary chondromas constitute CT which shows female predilection and may be a mosaic disorder. Even though there is some overlap between CT and CSS, as both are due to SDH deficiency, CSS is caused by inactivating germline mutations in genes encoding for the SDH subunits, while CT is mostly caused by a specific pattern of methylation of the SDHC gene and may be due to germline mosaicism of the responsible genetic defect.

Genetic ablation of pregnancy zone protein promotes breast cancer progression by activating TGF-β/SMAD signaling.

Pregnancy zone protein (PZP) is best known as protease inhibitor and its concentration in human blood plasma increases dramatically during pregnancy. Recent investigation revealed a role of PZP inactivating germ-line mutation in breast cancer predisposition, and therefore we designed a study to evaluate functional involvement of this protein in tumor pathogenesis. PZP knockout cells were generated utilizing the CRISPR-Cas9 approach in MCF7 and T47D (breast cancer) cell lines, and colony formation, cell proliferation, and migration assays carried out. TGF-β and SMAD expression studies were performed using qRT-PCR and Western blot. PZP expression in tumor vs normal tissue was compared using meta-analyses of data records of breast cancer patients (n = 1211) included in the TCGA consortium registry as well as in independent cohorts of hormone receptor-positive (n = 118) and triple-negative breast cancer (TNBC) patients (n = 116). We demonstrated that genetic ablation of PZP efficiently inhibits tamoxifen-induced apoptosis and enhances cell proliferation, migration, and colony-forming capacity. We found a significant increase in survival fraction of CRISPR/Cas9-mediated PZP knockout clones compared to wild-type counterpart after tamoxifen treatment (p < 0.05). The PZP knockout significantly promoted breast cancer cell migration (p < 0.01) in vitro. We observed high expression of TGF-β2 ligand, TGF-β- receptor 2, and upregulation of phosphorylated regulatory-SMADs (pSMAD2 and pSMAD3) activating the pro-survival function of TGF-β/SMAD signaling in PZP knockout clones. Meta-analyses of data records of breast cancer patients indicated that low PZP expression is associated with poor overall survival at 6years (51.7% vs 62.9% in low vs high expressers, respectively; p = 0.026). We alsoobserved a significantly lower PZP mRNA expression in TNBC as compared with hormone receptor-positive tumors (p = 0.019). Taken together, our results suggest that genetic ablation of PZP results in tumor progression and low expression of PZP is associated with poor survival of breast cancer patients.

793P CHEK2 inactivating germ-line mutations play a role in the development of testicular cancer

793P CHEK2 inactivating germ-line mutations play a role in the development of testicular cancer

Hereditary diffuse gastric cancer: updated clinical practice guidelines.

Hereditary diffuse gastric cancer (HDGC) is an autosomal dominant cancer syndrome that is characterised by a high prevalence of diffuse gastric cancer and lobular breast cancer. It is largely caused by inactivating germline mutations in the tumour suppressor gene CDH1, although pathogenic variants in CTNNA1 occur in a minority of families with HDGC. In this Policy Review, we present updated clinical practice guidelines for HDGC from the International Gastric Cancer Linkage Consortium (IGCLC), which recognise the emerging evidence of variability in gastric cancer risk between families with HDGC, the growing capability of endoscopic and histological surveillance in HDGC, and increased experience of managing long-term sequelae of total gastrectomy in young patients. To redress the balance between the accessibility, cost, and acceptance of genetic testing and the increased identification of pathogenic variant carriers, the HDGC genetic testing criteria have been relaxed, mainly through less restrictive age limits. Prophylactic total gastrectomy remains the recommended option for gastric cancer risk management in pathogenic CDH1 variant carriers. However, there is increasing confidence from the IGCLC that endoscopic surveillance in expert centres can be safely offered to patients who wish to postpone surgery, or to those whose risk of developing gastric cancer is not well defined.