Mutational spectrum in clinically aggressive low-grade serous carcinoma/serous borderline tumors of the ovary-Clinical significance of BRCA2 gene variants in genomically stable tumors.

OBJECTIVE: The mutational spectra of low-grade serous carcinomas (LGSCs) and serous borderline tumors (SBTs) of the ovary are poorly characterized. We present 17 cases of advanced or recurrent LGSC/SBT patients who underwent molecular profiling. METHODS: Thirteen LGSCs and four SBTs underwent targeted gene panel testing by massively parallel sequencing. Microsatellite stability and tumor mutation burdens (TMBs) were determined based on panel sequencing data. RESULTS: The mean TMB was 5.2 mutations/megabase (range 3-10) in 14 cases. Twelve of twelve (12/12) cases were microsatellite stable. Clear driver mutations were identified in 11 cases, namely KRAS (5/17), BRAF (2/17), NRAS (2/17) and ERBB2 (2/17). Five cases harbored BRCA2 alterations (allele fractions: 44-51%), including two classified as likely benign/benign variants, and three classified as variants of uncertain significance (VUSs), with two variants being confirmed to be germline. The three BRCA2 VUSs were missense variants that were assessed to be of unlikely clinical significance, based on family cancer history and expected impact on protein function. Two patients received PARP inhibitors during their disease course, with neither of the patients demonstrating appreciable response. CONCLUSIONS: The mutational spectra in 17 clinically aggressive SBT/LGSC cases demonstrate genomically stable tumors, frequently driven by the RTK/RAS/MAPK pathway. While BRCA2 variants were identified, our data demonstrate BRCA2 gene variants are at most VUSs and of dubious clinical significance, in contrast to disease-associated BRCA1/2 variants that may be identified in high-grade serous carcinoma. Germline testing and PARP inhibitors are thus expected to provide limited benefit to patients with LGSC/SBTs.

Second opinion pathologic review in the management of prostate cancer.

INTRODUCTION Inter-institutional re-review of prostate needle biopsy (PNBx) material is required at many institutions before definitive treatment, but adds time and cost and may not significantly alter urologic management. We aim to determine the utility of universal PNBx re-review on influencing the decision to recommend definitive local therapy for patients with prostate cancer. MATERIALS AND METHODS: From 2017-2020, 590 prostate biopsy specimens from outside institutions were re-reviewed at our center for patients considering prostatectomy. Clinical and pathologic characteristics from initial and secondary review were analyzed. Potential for change in treatment candidacy (CTC) was determined by re-diagnosis to non-malignant tissue or change in candidacy for active surveillance (AS) versus definitive treatment (i.e. prostatectomy or radiation therapy). Thus, the following scenarios were considered CTC: downgrading to non-malignant tissue, downgrading ISUP Grade Group (GG) ≥ 2 to GG1, and upgrading GG1 to GG ≥ 2. Any changes between GG2 to GG5 were not considered CTC, as definitive treatment would be offered to all groups. RESULTS: Overall, 55 patients (9.3%) had potential for CTC based on secondary review, all of whom had initial pathologic GG (iGG) ≤ 2. Of the 152 patients with iGG1, 8 were downgraded to no malignancy and 41 were upgraded to GG2 or GG3. Of the 185 patients with iGG2, 6 were downgraded to GG1. No patients with iGG ≥ 3 qualified for a CTC. Features associated with CTC included iGG, number of positive cores, and highest core percentage. Upon multivariable analysis, only iGG1 diagnosis was predictive of CTC (OR 23.66, p < 0.001). CONCLUSION: Second review may be helpful in determining need for definitive treatment in patients with GG1 and GG2 prostate cancer, i.e. those considering AS. This process appears unnecessary in GG3+ patients, as management for patients considering surgery would not change. This may allow for judicious redirection of hospital resources.

Metabolic acidosis in a lactating woman induced by a deliberate ketogenic diet.

ABSTRACT: This article describes a rare case of lactation ketoacidosis in a patient who started a ketogenic diet while nursing an infant and toddler. The patient presented to the ED with a history of nausea, vomiting, and postural dizziness, and was found to have a significant metabolic acidosis and elevated lipase level. The metabolic changes induced in this patient could occur in anyone with high metabolic demands who also is on a strict ketogenic diet. The case highlights the importance of a dietary history in patients with unexplained metabolic derangements.

Two types of primary mucinous ovarian tumors can be distinguished based on their origin.

The origin of primary mucinous ovarian tumors is unknown. We explore the hypothesis that they originate from either Brenner tumors or teratomas and examine differences between the tumors that arise in these settings. A total of 104 Brenner tumor-associated mucinous tumors and 58 teratoma-associated mucinous tumors were analyzed. Immunohistochemistry for 21 antigens and fluorescence in situ hybridization for ERBB2 and MYC were performed. Genome-wide copy number analysis and mutation analysis for 56 cancer-related genes was carried out on a subset of mucinous ovarian tumors and their complementary Brenner tumor or teratoma. Patients with teratoma-associated mucinous tumors were significantly younger than patients with Brenner tumor-associated mucinous tumors (43 vs. 61 years). During progression from cystadenoma to atypical proliferative mucinous (borderline) tumor to carcinoma expression of typical gastrointestinal markers was increased in both Brenner tumor-associated and teratoma-associated mucinous tumors. Brenner tumor-associated mucinous tumors showed more frequently calcifications and Walthard cell nests, rarely expressed SATB2 and showed more often co-deletion of CDKN2A and MTAP. Teratoma-associated mucinous tumors were characterized by mucinous stromal dissection, SATB2 expression and RNF43 mutations. Other frequent mutations in both Brenner tumor-associated and teratoma-associated mucinous tumors were TP53 and KRAS mutations. Based on identical mutations or copy number profiles clonal relationships were indicated in two mucinous tumors and their associated Brenner tumor. Teratomas and Brenner tumors give rise to different subtypes of mucinous ovarian tumors. Subsequent progression pathways are comparable since both Brenner tumor-associated and teratoma-associated mucinous tumors develop a gastrointestinal immunophenotype during progression and show early mutations in KRAS and TP53. Teratoma-associated mucinous tumors may more closely resemble true gastrointestinal tumors, indicated by their expression of SATB2 and the presence of RNF43 mutations.

An autologous humanized patient-derived-xenograft platform to evaluate immunotherapy in ovarian cancer.

OBJECTIVE: The aim of this study was to "humanize" ovarian cancer patient-derived xenograft (PDX) models by autologous transfer of patient-matched tumor infiltrating lymphocytes (TILs) to evaluate immunotherapies. METHODS: Orthotopic high-grade serous ovarian cancer (HGSOC) PDX models were established from three patient donors. Models were molecularly and histologically validated by immunohistochemistry. TILs were expanded from donor tumors using a rapid expansion protocol. Ex vivo TIL and tumor co-cultures were performed to validate TIL reactivity against patient-matched autologous tumor cells. Expression of TIL activation markers and cytokine secretion was quantitated by flow cytometry and ELISA. As proof of concept, the efficacy of anti-PD-1 monotherapy was tested in autologous TIL/tumor HGSOC PDX models. RESULTS: Evaluation of T-cell activation in autologous TIL/tumor co-cultures resulted in an increase in HLA-dependent IFNγ production and T-cell activation. In response to increased IFNγ production, tumor cell expression of PD-L1 was increased. Addition of anti-PD-1 antibody to TIL/tumor co-cultures increased autologous tumor lysis in a CCNE1 amplified model. Orthotopic HGSOC PDX models from parallel patient-matched tumors maintained their original morphology and molecular marker profile. Autologous tumor-reactive TIL administration in patient-matched PDX models resulted in reduced tumor burden and increased survival, in groups that also received anti-PD-1 therapy. CONCLUSIONS: This study validates a novel, clinically relevant model system for in vivo testing of immunomodulating therapeutic strategies for ovarian cancer, and provides a unique platform for assessing patient-specific T-cell response to immunotherapy.

The Implementation of an Introductory Surgical Pathology Didactic Series to Transition First Year Residents and Facilitate Upper Level Resident Teaching.

The increasing complexity of the practice of pathology and health care in general requires that pathology residents acquire a vast number of skills during their training. This has been reflected by the broad range of skills addressed in the Accreditation Council for Graduate Medical Education (ACGME) milestones. In order to address some of these milestones, our residency program instituted an introductory didactic series in surgical pathology that focused on 2 objectives. First, the didactics provided basic grossing and histology training to first year residents transitioning from medical school. Second, the sessions allowed upper level residents to refine their teaching and communication skills at the microscope and therefore served as an important career development tool. Surveys of both first year residents and the upper level residents that led these sessions confirm the utility of these didactics and the use of upper level residents to teach junior trainees. In addition, these sessions led to a dramatic increase in RISE scores among first year trainees. An introductory series with upper level residents leading slide sessions could easily be replicated at other institutions and provide similar benefits.

Innervation of cervical carcinoma is mediated by cancer-derived exosomes.

OBJECTIVE: Recently, our laboratory identified sensory innervation within head and neck squamous cell carcinomas (HNSCCs) and subsequently defined a mechanism whereby HNSCCs promote their own innervation via the release of exosomes that stimulate neurite outgrowth. Interestingly, we noted that exosomes from human papillomavirus (HPV)-positive cell lines were more effective at promoting neurite outgrowth than those from HPV-negative cell lines. As nearly all cervical tumors are HPV-positive, we hypothesized that these findings would extend to cervical cancer. METHODS: We use an in vitro assay with PC12 cells to quantify the axonogenic potential of cervical cancer exosomes. PC12 cells are treated with cancer-derived exosomes, stained with the pan-neuronal marker (ß-III tubulin) and the number of neurites quantified. To assess innervation in cervical cancer, we immunohistochemically stained cervical cancer patient samples for ß-III tubulin and TRPV1 (sensory marker) and compared the staining to normal cervix. RESULTS: Here, we show the presence of sensory nerves within human cervical tumors. Additionally, we show that exosomes derived from HPV-positive cervical cancer cell lines effectively stimulate neurite outgrowth. CONCLUSIONS: These data identify sensory nerves as components of the cervical cancer microenvironment and suggest that tumor- derived exosomes promote their recruitment.

An expanded immunohistochemical profile of osteoclast-rich undifferentiated carcinoma of the urinary tract.

Osteoclast-rich undifferentiated carcinoma of the urinary tract (ORUCUT) is a rare tumor composed of ovoid to spindle-shaped mononuclear cells with intermixed or focally clustered osteoclast-like giant cells. Previous studies have demonstrated that the mononuclear cells are neoplastic cells, while the giant cells are reactive cells of histiocytic lineage. The association between these tumors and classic urothelial carcinomas suggest that the mononuclear cells are derived from urothelial cells; however, no studies have been conducted to assess the immunohistochemical profile of ORUCUT with more specific urothelial markers. This study identified 21 cases of ORUCUT and performed immunohistochemistry for GATA3, uroplakin II, and thrombomodulin along with pancytokeratin (AE1/3) on all cases. Mononuclear cells stained positive in 20 cases (95%) for GATA3 and 19 cases (90%) for thrombomodulin. None of the mononuclear cells were positive for uroplakin II and only three cases showed focal positivity for AE1/3. The osteoclast-like giant cells were negative for GATA3, uroplakin II, thrombomodulin, and AE1/3, providing additional support to a reactive origin for these cells. Additionally, 15 cases (71%) were associated with either in situ or invasive urothelial carcinoma. This study provides an expanded immunohistochemical profile for ORUCUT and more definitively supports a urothelial origin for this tumor.

H2Bub1 loss is an early contributor to clear cell ovarian cancer progression.

Epigenetic aberrations, including posttranslational modifications of core histones, are major contributors to cancer. Here, we define the status of histone H2B monoubiquitylation (H2Bub1) in clear cell ovarian carcinoma (CCOC), low-grade serous carcinoma, and endometrioid carcinomas. We report that clear cell carcinomas exhibited profound loss, with nearly all cases showing low or negative H2Bub1 expression. Moreover, we found that H2Bub1 loss occurred in endometriosis and atypical endometriosis, which are established precursors to CCOCs. To examine whether dysregulation of a specific E3 ligase contributes to the loss of H2Bub1, we explored expression of ring finger protein 40 (RNF40), ARID1A, and UBR7 in the same case cohort. Loss of RNF40 was significantly and profoundly correlated with loss of H2Bub1. Using genome-wide DNA methylation profiles of 230 patients with CCOC, we identified hypermethylation of RNF40 in CCOC as a likely mechanism underlying the loss of H2Bub1. Finally, we demonstrated that H2Bub1 depletion promoted cell proliferation and clonogenicity in an endometriosis cell line. Collectively, our results indicate that H2Bub1 plays a tumor-suppressive role in CCOCs and that its loss contributes to disease progression.

Dual blockade of BRD4 and ATR/WEE1 pathways exploits ARID1A loss in clear cell ovarian cancer.

ARID1A, an epigenetic tumor suppressor, is the most common gene mutation in clear-cell ovarian cancers (CCOCs). CCOCs are often resistant to standard chemotherapy and lack effective therapies. We hypothesized that ARID1A loss would increase CCOC cell dependency on chromatin remodeling and DNA repair pathways for survival. We demonstrate that combining BRD4 inhibitor (BRD4i) with DNA damage response inhibitors (ATR or WEE1 inhibitors; e.g. BRD4i-ATRi) was synergistic at low doses leading to decreased survival, and colony formation in CCOC in an ARID1A dependent manner. BRD4i-ATRi caused significant tumor regression and increased overall survival in ARID1AMUT but not ARID1AWT patient-derived xenografts. Combination BRD4i-ATRi significantly increased γH2AX, and decreased RAD51 foci and BRCA1 expression, suggesting decreased ability to repair DNA double-strand-breaks (DSBs) by homologous-recombination in ARID1AMUT cells, and these effects were greater than monotherapies. These studies demonstrate BRD4i-ATRi is an effective treatment strategy that capitalizes on synthetic lethality with ARID1A loss in CCOC.

Functional neuronal circuits promote disease progression in cancer.

The molecular and functional contributions of intratumoral nerves to disease remain largely unknown. We localized synaptic markers within tumors suggesting that these nerves form functional connections. Consistent with this, electrophysiological analysis shows that malignancies harbor significantly higher electrical activity than benign disease or normal tissues. We also demonstrate pharmacologic silencing of tumoral electrical activity. Tumors implanted in transgenic animals lacking nociceptor neurons show reduced electrical activity. These data suggest that intratumoral nerves remain functional at the tumor bed. Immunohistochemical staining demonstrates the presence of the neuropeptide, Substance P (SP), within the tumor space. We show that tumor cells express the SP receptor, NK1R, and that ligand/receptor engagement promotes cellular proliferation and migration. Our findings identify a mechanism whereby intratumoral nerves promote cancer progression.

Keratin Granulomas in the Peritoneum on Frozen Section: A Case Report with Multiple Suspects and the Search for the Culprit.

Keratin granulomas in the peritoneum are a rare finding with multiple etiologies and can be especially challenging for both the pathologist and the surgeon when these lesions are grossly visible. We report a case of a unique frozen section diagnostic scenario of evaluation of keratin granulomas in the peritoneum of a 47-year-old woman in the setting of multiple potential culprits: endometrial endometrioid adenocarcinoma following fertility sparing treatment, and a concurrent dermoid cyst. We discuss the various etiologies of keratin granulomas in the peritoneum, mechanism of their formation, diagnostic significance, as well as implications of fertility sparing treatments. To the best of our knowledge, this is the only case of keratin granulomas in the peritoneum with multiple distinct potential pathologic culprits as well the only case following fertility sparing treatment.

Renal Oncocytoma With Both Lymphovascular Invasion and Prominent Intracytoplasmic Vacuole-Like Spaces: A Case Report and Review of the Literature.

Here we report a case of renal oncocytoma in a 68 year-old male. The diagnosis was initially made on a needle biopsy 6 years prior to the partial nephrectomy. The case is unique that in addition to the gross and microscopic features commonly seen in renal oncocytomas, both lymphovascular invasion and prominent intracytoplasmic vacuole-like spaces are also present in this tumor. Although vascular invasion is increasingly recognized as compatible with renal oncocytoma, intracytoplasmic vacuoles are a rare and unusual finding that may lead to diagnostic difficulty. The diagnosis of renal oncocytoma was confirmed after immunohistochemistry was performed to argue against succinate dehydrogenase deficient renal cell carcinoma (RCC) and chromophobe RCC. This case highlights the importance for practicing pathologists to recognize the rare co-occurrence of lymphovascular invasion and large intracytoplasmic vacuole-like spaces in renal oncocytoma. Other differential diagnoses may include emerging renal tumor entities, such as the recently-proposed eosinophilic vacuolated tumor.

Recognition Awards in Pathology Specialty Societies.

OBJECTIVES: Recognition awards build physician reputation and facilitate career advancement. We hypothesize women physicians are underrepresented as award recipients by pathology medical societies compared with representation in the specialty. METHODS: We analyzed publicly available online information about physician recipients (January 2015 to December 2021) from three general pathology society websites. Recipient gender was determined by pronoun use, first name, and photograph. Representation was compared with Association of American Medical Colleges (AAMC) specialty data from 2015 and 2019, which showed a minimum of 36.7% women pathologists in 2015 and up to 43.4% in 2019. RESULTS: Twenty-six awards and 230 physician recipients were included in the analysis. A total of 159 (69.1%) men physicians and 71 (30.9%) women physicians received awards. Overall, women physicians were underrepresented in recognition awards compared with AAMC benchmarks. Prestigious awards (defined as those that recognize a person's body of work over time) showed a similar disparity with 22 (30.1%) of 73 recipients being women. Men physicians were more likely to receive multiple awards. CONCLUSIONS: Women physicians are underrepresented overall for recognition awards by pathology medical societies. Disparities are greater for prestigious awards. Further research is needed to better understand the reasons for these findings and how they affect women physicians' careers.

L1CAM is required for early dissemination of fallopian tube carcinoma precursors to the ovary.

Most ovarian high-grade serous carcinomas (HGSC) arise from Serous Tubal Intraepithelial Carcinoma (STIC) lesions in the distal end of the fallopian tube (FT). Formation of STIC lesions from FT secretory cells leads to seeding of the ovarian surface, with rapid tumor dissemination to other abdominal structures thereafter. It remains unclear how nascent malignant cells leave the FT to colonize the ovary. This report provides evidence that the L1 cell adhesion molecule (L1CAM) contributes to the ability of transformed FT secretory cells (FTSEC) to detach from the tube, survive under anchorage-independent conditions, and seed the ovarian surface. L1CAM was highly expressed on the apical cells of STIC lesions and contributed to ovarian colonization by upregulating integrins and fibronectin in malignant cells and activating the AKT and ERK pathways. These changes increased cell survival under ultra-low attachment conditions that mimic transit from the FT to the ovary. To study dissemination to the ovary, we developed a tumor-ovary co-culture model. We showed that L1CAM expression was important for FT cells to invade the ovary as a cohesive group. Our results indicate that in the early stages of HGSC development, transformed FTSECs disseminate from the FT to the ovary in a L1CAM-dependent manner.

Integrated Analysis of Ovarian Juvenile Granulosa Cell Tumors Reveals Distinct Epigenetic Signatures and Recurrent TERT Rearrangements.

PURPOSE: Adult granulosa cell tumor (AGCT) is characterized by the somatic FOXL2 p.C134W mutation, and recurrences have been associated with TERT promoter and KMT2D-truncating mutations. Conversely, the molecular underpinnings of the rare juvenile granulosa cell tumor (JGCT) have not been well elucidated. To this end, we applied a tumor-only integrated approach to investigate the genomic, transcriptomic, and epigenomic landscape of 31 JGCTs to identify putative oncogenic drivers. EXPERIMENTAL DESIGN: Multipronged analyses of 31 JGCTs were performed utilizing a clinically validated next-generation sequencing (NGS) panel targeting 580 cancer-related genes for genomic interrogation, in addition to targeted RNA NGS for transcriptomic exploration. Genome-wide DNA methylation profiling was conducted using an Infinium Methylation EPIC array targeting 866,562 CpG methylation sites. RESULTS: We identified frequent KMT2C-truncating mutations along with other mutated genes implicated in the switch/sucrose nonfermentable (SWI/SNF) chromatin remodeling complex, in addition to previously reported hotspot AKT1 and DICER1 mutations. Targeted transcriptome sequencing revealed recurrent TERT rearrangements (13%) involving partners CLPTM1L or DROSHA, and differential gene expression analysis showed FGFR1 upregulation in the TERT non-rearranged JGCTs under direct promoter control. Genome-wide DNA methylation rendered a clear delineation between AGCTs and JGCTs at the epigenomic level, further supporting its diagnostic utility in distinguishing among these tumors. CONCLUSIONS: This is the largest comprehensive molecular study of JGCTs, where we further expand our current understanding of JGCT pathogenesis and demonstrate putative oncogenic drivers and TERT rearrangements in a subset of tumors. Our findings further offer insights into possible targeted therapies in a rare entity.

Association of Inherited Mutations in DNA Repair Genes with Localized Prostate Cancer.

BACKGROUND: Identification of germline mutations in DNA repair genes has significant implications for the personalized treatment of individuals with prostate cancer (PrCa). OBJECTIVE: To determine DNA repair genes associated with localized PrCa in a diverse academic biobank and to determine genetic testing burden. DESIGN, SETTING, AND PARTICIPANTS: A cross-sectional study of 2391 localized PrCa patients was carried out. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Genetic ancestry and mutation rates (excluding somatic interference) in 17 DNA repair genes were determined in 1588 localized PrCa patients and 3273 cancer-free males. Burden testing within individuals of genetically determined European (EUR) and African (AFR) ancestry was performed between biobank PrCa cases and cancer-free biobank and gnomAD males. RESULTS AND LIMITATIONS: AFR individuals with localized PrCa had lower DNA repair gene mutation rates than EUR individuals (1.4% vs 4.0%, p = 0.02). Mutation rates in localized PrCa patients were similar to those in biobank and gnomAD controls (EUR: 4.0% vs 2.8%, p = 0.15, vs 3.1%, p = 0.04; AFR: 1.4% vs 1.8%, p = 0.8, vs 2.1%, p = 0.5). Gene-based rare variant association testing revealed that only BRCA2 mutations were significantly enriched compared with gnomAD controls of EUR ancestry (1.0% vs 0.28%, p = 0.03). Of the participants, 21% and 11% met high-risk and very-high-risk criteria; of them, 3.7% and 6.2% had any germline genetic mutation and 1.0% and 2.5% had a BRCA2 mutation, respectively. Limitations of this study include an analysis of a relatively small, single-institution cohort. CONCLUSIONS: DNA repair gene germline mutation rates are low in an academic biobank cohort of localized PrCa patients, particularly among individuals of AFR genetic ancestry. Mutation rates in genes with published evidence of association with PrCa exceed 2.5% only in high-risk, very-high-risk localized, and node-positive PrCa patients. These findings highlight the importance of risk stratification in localized PrCa patients to identify appropriate patients for germline genetic testing. PATIENT SUMMARY: In the majority of patients who develop localized prostate cancer, germline genetic testing is unlikely to reveal an inherited DNA repair mutation, regardless of race. High-risk features increase the possibility of a germline DNA repair mutation.

Inherited TP53 Variants and Risk of Prostate Cancer.

BACKGROUND: Inherited germline TP53 pathogenic and likely pathogenic variants (gTP53) cause autosomal dominant multicancer predisposition including Li-Fraumeni syndrome (LFS). However, there is no known association of prostate cancer with gTP53. OBJECTIVE: To determine whether gTP53 predisposes to prostate cancer. DESIGN, SETTING, AND PARTICIPANTS: This multi-institutional retrospective study characterizes prostate cancer incidence in a cohort of LFS males and gTP53 prevalence in a prostate cancer cohort. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: We evaluated the spectrum of gTP53 variants and clinical features associated with prostate cancer. RESULTS AND LIMITATIONS: We identified 31 prostate cancer cases among 163 adult LFS males, including 26 of 54 aged ≥50 yr. Among 117 LFS males without prostate cancer at the time of genetic testing, six were diagnosed with prostate cancer over a median (interquartile range [IQR]) of 3.0 (1.3-7.2) yr of follow-up, a 25-fold increased risk (95% confidence interval [CI] 9.2-55; p < 0.0001). We identified gTP53 in 38 of 6850 males (0.6%) in the prostate cancer cohort, a relative risk 9.1-fold higher than that of population controls (95% CI 6.2-14; p < 0.0001; gnomAD). We observed hotspots at the sites of attenuated variants not associated with classic LFS. Two-thirds of available gTP53 prostate tumors had somatic inactivation of the second TP53 allele. Among gTP53 prostate cancer cases in this study, the median age at diagnosis was 56 (IQR: 51-62) yr, 44% had Gleason ≥8 tumors, and 29% had advanced disease at diagnosis. CONCLUSIONS: Complementary analyses of prostate cancer incidence in LFS males and gTP53 prevalence in prostate cancer cohorts suggest that gTP53 predisposes to aggressive prostate cancer. Prostate cancer should be considered as part of LFS screening protocols and TP53 considered in germline prostate cancer susceptibility testing. PATIENT SUMMARY: Inherited pathogenic variants in the TP53 gene are likely to predispose men to aggressive prostate cancer.

Progesterone Receptors Promote Quiescence and Ovarian Cancer Cell Phenotypes via DREAM in p53-Mutant Fallopian Tube Models.

CONTEXT: The ability of ovarian steroids to modify ovarian cancer (OC) risk remains controversial. Progesterone is considered to be protective; recent studies indicate no effect or enhanced OC risk. Knowledge of progesterone receptor (PR) signaling during altered physiology that typifies OC development is limited. OBJECTIVE: This study defines PR-driven oncogenic signaling mechanisms in p53-mutant human fallopian tube epithelia (hFTE), a precursor of the most aggressive OC subtype. METHODS: PR expression in clinical samples of serous tubal intraepithelial carcinoma (STIC) lesions and high-grade serous OC (HGSC) tumors was analyzed. Novel PR-A and PR-B isoform-expressing hFTE models were characterized for gene expression and cell cycle progression, emboli formation, and invasion. PR regulation of the DREAM quiescence complex and DYRK1 kinases was established. RESULTS: STICs and HGSC express abundant activated phospho-PR. Progestin promoted reversible hFTE cell cycle arrest, spheroid formation, and invasion. RNAseq/biochemical studies revealed potent ligand-independent/-dependent PR actions, progestin-induced regulation of the DREAM quiescence complex, and cell cycle target genes through enhanced complex formation and chromatin recruitment. Disruption of DREAM/DYRK1s by pharmacological inhibition, HPV E6/E7 expression, or DYRK1A/B depletion blocked progestin-induced cell arrest and attenuated PR-driven gene expression and associated OC phenotypes. CONCLUSION: Activated PRs support quiescence and pro-survival/pro-dissemination cell behaviors that may contribute to early HGSC progression. Our data support an alternative perspective on the tenet that progesterone always confers protection against OC. STICs can reside undetected for decades prior to invasive disease; our studies reveal clinical opportunities to prevent the ultimate development of HGSC by targeting PRs, DREAM, and/or DYRKs.

Targeting glutamine dependence through GLS1 inhibition suppresses ARID1A-inactivated clear cell ovarian carcinoma.

Alterations in components of the SWI/SNF chromatin-remodeling complex occur in ~20% of all human cancers. For example, ARID1A is mutated in up to 62% of clear cell ovarian carcinoma (OCCC), a disease currently lacking effective therapies. Here we show that ARID1A mutation creates a dependence on glutamine metabolism. SWI/SNF represses glutaminase (GLS1) and ARID1A inactivation upregulates GLS1. ARID1A inactivation increases glutamine utilization and metabolism through the tricarboxylic acid cycle to support aspartate synthesis. Indeed, glutaminase inhibitor CB-839 suppresses the growth of ARID1A mutant, but not wildtype, OCCCs in both orthotopic and patient-derived xenografts. In addition, glutaminase inhibitor CB-839 synergizes with immune checkpoint blockade anti-PDL1 antibody in a genetic OCCC mouse model driven by conditional Arid1a inactivation. Our data indicate that pharmacological inhibition of glutaminase alone or in combination with immune checkpoint blockade represents an effective therapeutic strategy for cancers involving alterations in the SWI/SNF complex such as ARID1A mutations.