The Silva pattern-based classification for HPV-associated endocervical adenocarcinoma: A single institution concordance study of trainees and gynecologic pathologists.

The Silva pattern-based classification of HPV-associated endocervical adenocarcinoma has become an integral part of the histologic assessment of these tumors. Unfortunately, the Silva system reproducibility has had mixed results in past studies, and clinical practice still favors the FIGO stage assessment in directing therapeutic interventions for patients. In our study, we aimed to assess our institution's concordance including not only gynecologic pathologists, but also pathology trainees through a series of 69 cases. The grouped total kappa concordance from all participants was 0.439 (Moderate), with an overall trainee kappa of 0.417 (moderate) and an overall pathologist kappa of 0.460 (moderate). Perfect concordance among all 10 study participants was seen in 8/69 cases (11.6 %), corresponding to 5/22 Pattern A cases (22.7 %), 0/16 Pattern B cases (0 %), and 3/31 Pattern C cases (9.7 %), with similar findings between trainees and pathologists when compared within their own cohorts. Recurrence was identified in 2 Pattern A cases, indicating a potential issue with limited excisional specimens which may not fully appreciate the true biologic aggressiveness of the lesions.

Splicing Factor PQBP1 Curtails BAX Expression to Promote Ovarian Cancer Progression.

Splicing factor polyglutamine binding protein-1 (PQBP1) is abundantly expressed in the central nervous system during development, and mutations in the gene cause intellectual disability. However, the roles of PQBP1 in cancer progression remain largely unknown. Here, it is shown that PQBP1 overexpression promotes tumor progression and indicates worse prognosis in ovarian cancer. Integrative analysis of spyCLIP-seq and RNA-seq data reveals that PQBP1 preferentially binds to exon regions and modulates exon skipping. Mechanistically, it is shown that PQBP1 regulates the splicing of genes related to the apoptotic signaling pathway, including BAX. PQBP1 promotes BAX exon 2 skipping to generate a truncated isoform that undergoes degradation by nonsense-mediated mRNA decay, thus making cancer cells resistant to apoptosis. In contrast, PQBP1 depletion or splice-switching antisense oligonucleotides promote exon 2 inclusion and thus increase BAX expression, leading to inhibition of tumor growth. Together, the results demonstrate an oncogenic role of PQBP1 in ovarian cancer and suggest that targeting the aberrant splicing mediated by PQBP1 has therapeutic potential in cancer treatment.

Racial disparity in uterine leiomyoma: new insights of genetic and environmental burden in myometrial cells.

Uterine leiomyoma (LM), also known as uterine fibroids, are common gynecological tumors and can reach a prevalence of 70% among women by the age of 50 years. Notably, the LM burden is much higher in Black women with earlier onset, a greater tumor number, size, and severity compared to White women. Published knowledge shows that there are genetic, environmental, and lifestyle-based risk factors associated with racial disparity for LM. Significant strides have been made on genomic, epigenomic, and transcriptomic data levels in Black and White women to elucidate the underlying pathomolecular reasons of racial disparity in LM development. However, racial disparity of LM remains a major area of concern in gynecological research. This review highlights risk factors of LM and their role in different races. Furthermore, we discuss the genetics and uterine myometrial microenvironment in LM development. Comparative findings revealed that a major racial difference in the disease is linked to myometrial oxidative burden and altered ROS pathways which is relevant to the oxidized guanine in genomic DNA and MED12 mutations that drive the LM genesis. Considering the burden and morbidity of LM, we anticipate that this review on genetic risk and myometrial microenvironment will strengthen understanding and propel the growth of research to address the racial disparity of LM burden.

Preclinical Evaluation of NTX-301, a Novel DNA Hypomethylating Agent in Ovarian Cancer.

PURPOSE: DNA methylation causes silencing of tumor-suppressor and differentiation-associated genes, being linked to chemoresistance. Previous studies demonstrated that hypomethylating agents (HMA) resensitize ovarian cancer to chemotherapy. NTX-301 is a highly potent and orally bioavailable HMA, in early clinical development. EXPERIMENTAL DESIGN: The antitumor effects of NTX-301 were studied in ovarian cancer models by using cell viability, stemness and ferroptosis assays, RNA sequencing, lipidomic analyses, and stimulated Raman spectroscopy. RESULTS: Ovarian cancer cells (SKOV3, IC50 = 5.08 nmol/L; OVCAR5 IC50 = 3.66 nmol/L) were highly sensitive to NTX-301 compared with fallopian tube epithelial cells. NTX-301 downregulated expression of DNA methyltransferases 1-3 and induced transcriptomic reprogramming with 15,000 differentially expressed genes (DEG, P < 0.05). Among them, Gene Ontology enrichment analysis identified regulation of fatty acid biosynthesis and molecular functions related to aldehyde dehydrogenase (ALDH) and oxidoreductase, known features of cancer stem cells. Low-dose NTX-301 reduced the ALDH(+) cell population and expression of stemness-associated transcription factors. Stearoyl-coenzyme A desaturase 1 (SCD), which regulates production of unsaturated fatty acids (UFA), was among the top DEG downregulated by NTX-301. NTX-301 treatment decreased levels of UFA and increased oxidized lipids, and this was blunted by deferoxamine, indicating cell death via ferroptosis. NTX-301-induced ferroptosis was rescued by oleic acid. In vivo, monotherapy with NTX-301 significantly inhibited ovarian cancer and patient-derived xenograft growth (P < 0.05). Decreased SCD levels and increased oxidized lipids were detected in NTX-301-treated xenografts. CONCLUSIONS: NTX-301 is active in ovarian cancer models. Our findings point to a new mechanism by which epigenetic blockade disrupts lipid homeostasis and promotes cancer cell death.

Epidemiology and survival outcomes of HIV-associated cervical cancer in Nigeria.

INTRODUCTION: Invasive cervical cancer (ICC) is an HIV-associated cancer that is preventable and precancerous stages including early ICC stages could be detected through screening offering opportunities for treatment and cure. The high incidence in women living with HIV and late presentation often at advanced stages of ICC with limited treatment facilities often result in early mortality. We sought to compare the epidemiologic characteristics and survival differences in HIV status of ICC patients in Nigeria. METHODS: We conducted a cohort study at two federal academic hospital-based research sites in Jos University Teaching Hospital, and Lagos University Teaching Hospital Nigeria, between March 2018 and September 2022. We enrolled women with histologically confirmed ICC with known HIV status, and FIGO staging as part of the United States of America's National Institutes of Health/National Cancer Institute funded project titled 'Epigenomic Biomarkers of HIV-Associated Cancers in Nigeria'. The primary outcome was all-cause mortality with assessment of overall survival (OS) and time to death after ICC diagnosis. OS distribution was estimated using the method of Kaplan-Meier and compared between groups using the log-rank test. RESULTS: A total of 239 women with confirmed ICC were enrolled and included in this analysis, of whom 192 (80.3%) were HIV-negative (HIV-/ICC +), and 47 (19.7%) were HIV-positive (HIV +/ICC +). The HIV +/ICC + patients were younger with median age 46 (IQR: 40-51) years compared to 57 (IQR: 45-66) among HIV-/ICC + (P < 0.001). Squamous cell carcinoma was the commonest histopathologic variant in 80.4% of ICC diagnosis, moderately differentiated tumor grade in 68.1% in both groups. HIV +/ICC + diagnosis was at FIGO advanced stages in 64.9% compared to 47.9% in HIV-/ICC +. The HIV-/ICC + women had better OS compared to HIV +/ICC + participants (p = 0.018), with 12-month OS 84.1% (95%CI 75-90%) and 67.6% (95%CI 42-84%) respectively. CONCLUSION: ICC is diagnosed at a relatively young age in women living with HIV, with a significantly lower overall survival probability compared to women without HIV. The trend of presentation and diagnosis at advanced stages in women living with HIV could partly explain the differences in overall survival.

Epidemiology and Survival outcomes of HIV-associated cervical cancer in Nigeria.

Introduction: Invasive cervical cancer (ICC) is an HIV-associated cancer that is preventable and precancerous stages including early ICC stages could be detected through screening offering opportunities for treatment and cure. The high incidence in women living with HIV and late presentation often at advanced stages of ICC with limited treatment facilities often result in early mortality. We sought to compare the epidemiologic characteristics and survival differences in HIV status of ICC patients in Nigeria. Methods: We conducted a cohort study at two federal academic hospital-based research sites in Jos University Teaching Hospital, and Lagos University Teaching Hospital Nigeria, between March 2018 and September 2022. We enrolled women with histologically confirmed ICC with known HIV status, and FIGO staging as part of the United States of America's National Institutes of Health/National Cancer Institute funded project titled 'Epigenomic Biomarkers of HIV-Associated Cancers in Nigeria'. The primary outcome was all-cause mortality with assessment of overall survival (OS) and time to death after ICC diagnosis. OS distribution was estimated using the method of Kaplan-Meier and compared between groups using the log-rank test. Results: A total of 239 women with confirmed ICC were enrolled and included in this analysis, of whom 192 (80.3%) were HIV-negative (HIV-/ICC+), and 47 (19.7%) were HIV-positive (HIV+/ICC+). The HIV+/ICC) patients were younger with median age 46 (IQR: 40-51) years compared to 57 (IQR: 45-66) among HIV-/ICC+) (P<0.001. Squamous cell carcinoma was the commonest histopathologic variant in 80.4% of ICC diagnosis, moderately differentiated tumor grade in 68.1% in both groups. HIV+/ICC+ diagnosis was at FIGO advanced stages in 64.9% compared to 47.9% in HIV-/ICC+. The HIV-/ICC+ women had better OS compared to HIV+/ICC+ participants (p=0.018), with 12-month OS 84.1% (95%CI: 75% - 90%) and 67.6% (95%CI: 42%-84%) respectively. Conclusion: ICC is diagnosed at a relatively young age in women living with HIV, with a significantly lower overall survival probability compared to women without HIV. The trend of presentation and diagnosis at advanced stages in women living with HIV could partly explain the differences in overall survival.

Engineered MED12 mutations drive leiomyoma-like transcriptional and metabolic programs by altering the 3D genome compartmentalization.

Nearly 70% of Uterine fibroid (UF) tumors are driven by recurrent MED12 hotspot mutations. Unfortunately, no cellular models could be generated because the mutant cells have lower fitness in 2D culture conditions. To address this, we employ CRISPR to precisely engineer MED12 Gly44 mutations in UF-relevant myometrial smooth muscle cells. The engineered mutant cells recapitulate several UF-like cellular, transcriptional, and metabolic alterations, including altered Tryptophan/kynurenine metabolism. The aberrant gene expression program in the mutant cells is, in part, driven by a substantial 3D genome compartmentalization switch. At the cellular level, the mutant cells gain enhanced proliferation rates in 3D spheres and form larger lesions in vivo with elevated production of collagen and extracellular matrix deposition. These findings indicate that the engineered cellular model faithfully models key features of UF tumors and provides a platform for the broader scientific community to characterize genomics of recurrent MED12 mutations.

Endometriosis and adenomyosis: shared pathophysiology.

Endometriosis and adenomyosis are closely related disorders. Their pathophysiologies are extremely similar. Both tissues originate from the eutopically located intracavitary endometrium. Oligoclones of endometrial glandular epithelial cells with somatic mutations and attached stromal cells may give rise to endometriosis if they travel to peritoneal surfaces or the ovary via retrograde menstruation and/or may be entrapped in the myometrium to give rise to adenomyosis. In both instances, the endometrial cell populations possess survival and growth capabilities conferred by somatic epithelial mutations and epigenetic abnormalities in stromal cells. Activating mutations of KRAS are the most commonly found genetic variant in endometriotic epithelial cells, whereas the adenomyotic epithelial cells almost exclusively bear KRAS mutations. Epigenetic abnormalities in the stromal cells of endometriosis and adenomyosis are very similar and involve an abnormal expression pattern of nuclear receptors, including the steroid receptors. These epigenetic defects give rise to excessive local estrogen biosynthesis by aromatase and abnormal estrogen action via estrogen receptor-ß. Deficient progesterone receptor expression results in progesterone resistance in both endometriosis and adenomyosis.

Borderline With Bad Behavior: An Unusual Low-grade Serous Carcinoma With Dedifferentiation From a Serous Borderline Tumor.

The pathogenesis of serous ovarian tumors has been extensively investigated, with a dualistic model dividing these cancers into 2 groups. Type I tumors, including low-grade serous carcinoma, is characteristic for concurrent presence of borderline tumors, less atypical cytology, relatively indolent biologic behavior, and molecular aberrations related to the MAPK pathway with chromosomal stability. Meanwhile, type II tumors, such as high-grade serous carcinoma, are notable for no significant association with borderline tumors, higher grade cytology, more aggressive biologic behavior, and TP53 mutations along with chromosomal instability. We describe a case of morphologic low-grade serous carcinoma with focally increased cytologic atypia arising in serous borderline tumors involving both ovaries, which demonstrated highly aggressive behavior despite several years of surgical and chemotherapeutic management. Each recurrent specimen contained more uniform higher grade morphology than what was seen in the original specimen. Immunohistochemical and molecular studies in both the original tumor and the most recent recurrence demonstrate identical mutations in the MAPK genes, but with additional mutations in the latter, notably an acquisition of a variant of possible clinical significance in the SMARCA4 gene, which is associated with dedifferentiation and aggressive biologic behavior. This case challenges our current and still evolving understanding of the pathogenesis, biologic behavior, and expected clinical outcome of low-grade serous ovarian carcinomas. It also underscores the need for further investigation into this complicated tumor.

Adenomyosis: single-cell transcriptomic analysis reveals a paracrine mesenchymal-epithelial interaction involving the WNT/SFRP pathway.

OBJECTIVE: To assess the cellular and molecular landscape of adenomyosis. DESIGN: Single-cell analysis of genome-wide messenger RNA (mRNA) expression (single-cell RNA sequencing) of matched tissues of endometrium, adenomyosis, and myometrium using relatively large numbers of viable cells. SETTING: Not applicable. PATIENT(S): Patients (n = 3, age range 40-44 years) undergoing hysterectomy for diffuse adenomyosis. MAIN OUTCOME MEASURE(S): Definition of the molecular landscape of matched adenomyotic, endometrial and myometrial tissues from the same uterus using single-cell RNA sequencing and comparison of distinct cell types in these tissues to identify disease-specific cell populations, abnormal gene expression and pathway activation, and mesenchymal-epithelial interactions. RESULT(S): The largest cell population in the endometrium was composed of closely clustered fibroblast groups, which comprise 36% of all cells and seem to originate from pericyte progenitors differentiating to estrogen/progesterone receptor-expressing endometrial stromal- cells. In contrast, the entire fibroblast population in adenomyosis comprised a larger (50%) portion of all cells and was not linked to any pericyte progenitors. Adenomyotic fibroblasts eventually differentiate into extracellular matrix protein-expressing fibroblasts and smooth muscle cells. Hierarchical clustering of mRNA expression revealed a unique adenomyotic fibroblast population that clustered transcriptomically with endometrial fibroblasts, suggestive of an endometrial stromal cell population serving as progenitors of adenomyosis. Four other adenomyotic fibroblast clusters with disease-specific transcriptomes were distinct from those of endometrial or myometrial fibroblasts. The mRNA levels of the natural WNT inhibitors, named, secreted frizzled-related proteins 1, 2, and 4, were higher in these 4 adenomyotic fibroblast clusters than in endometrial fibroblast clusters. Moreover, we found that multiple WNTs, which originate from fibroblasts and target ciliated and unciliated epithelial cells and endothelial cells, constitute a critical paracrine signaling network in adenomyotic tissue. Compared with endometrial tissue, unciliated and ciliated epithelial cells in adenomyosis comprised a significantly smaller portion of this tissue and exhibited molecular evidence of progesterone resistance and diminished regulation of estrogen signaling. CONCLUSION(S): We found a high degree of heterogeneity in fibroblast-like cells in the adenomyotic uterus. The WNT signaling involving differential expression of secreted frizzled-related proteins, which act as decoy receptors for WNTs, in adenomyotic fibroblasts may have a key role in the pathophysiology of this disease.

Engineered MED12 mutations drive uterine fibroid-like transcriptional and metabolic programs by altering the 3D genome compartmentalization.

Uterine fibroid (UF) tumors originate from a mutated smooth muscle cell (SMC). Nearly 70% of these tumors are driven by hotspot recurrent somatic mutations in the MED12 gene; however, there are no tractable genetic models to study the biology of UF tumors because, under culture conditions, the non-mutant fibroblasts outgrow the mutant SMC cells, resulting in the conversion of the population to WT phenotype. The lack of faithful cellular models hampered our ability to delineate the molecular pathways downstream of MED12 mutations and identify therapeutics that may selectively target the mutant cells. To overcome this challenge, we employed CRISPR knock-in with a sensitive PCR-based screening strategy to precisely engineer cells with mutant MED12 Gly44, which constitutes 50% of MED12 exon two mutations. Critically, the engineered myometrial SMC cells recapitulate several UF-like cellular, transcriptional and metabolic alterations, including enhanced proliferation rates in 3D spheres and altered Tryptophan/kynurenine metabolism. Our transcriptomic analysis supported by DNA synthesis tracking reveals that MED12 mutant cells, like UF tumors, have heightened expression of DNA repair genes but reduced DNA synthesis rates. Consequently, these cells accumulate significantly higher rates of DNA damage and are selectively more sensitive to common DNA-damaging chemotherapy, indicating mutation-specific and therapeutically relevant vulnerabilities. Our high-resolution 3D chromatin interaction analysis demonstrates that the engineered MED12 mutations drive aberrant genomic activity due to a genome-wide chromatin compartmentalization switch. These findings indicate that the engineered cellular model faithfully models key features of UF tumors and provides a novel platform for the broader scientific community to characterize genomics of recurrent MED12 mutations and discover potential therapeutic targets.

Racial differences in transcriptomics and reactive oxygen species burden in myometrium and leiomyoma.

STUDY QUESTION: Are there differences in Mediator Complex Subunit 12 mutations (MED12) mutation, transcriptomics, and protein expression in uterine myometrium and leiomyomas of Black and White women? SUMMARY ANSWER: RNA sequencing, tissue microarray, and immunohistochemistry data revealed that Black and White women have significant differences in their myometrium and leiomyoma profiles. WHAT IS KNOWN ALREADY: Black women develop uterine leiomyoma earlier than White women, and are more likely to be anemic, have multiple tumors, undergo hysterectomy at an earlier age, have a higher uterine weight, and report very severe pelvic pain. STUDY DESIGN, SIZE, DURATION: Uterine tissues were collected from premenopausal women undergoing hysterectomy or myomectomy at Northwestern University Prentice Women's Hospital (Chicago, IL) from 2010 to 2021. Tissues were collected from a total of 309 women, including from 136 Black women, 135 White women, and 38 women from other racial groups. A total of 529 uterine leiomyomas (290 from Black women, 184 from White women, and 55 from women of other racial groups) were subjected to molecular analysis. Leiomyoma and matched myometrium from a total of 118 cases including 60 Black women and 58 White women, were used for tissue microarrays, along with 34 samples of myometrium without leiomyoma from White women. PARTICIPANTS/MATERIALS, SETTING, METHODS: Tissues from the above patient cohorts were analyzed by tissue microarray, immunohistochemistry, RNA sequencing, and mutation analysis. MAIN RESULTS AND THE ROLE OF CHANCE: The results indicated that leiomyoma from Black women have a higher rate of MED12 mutations (79.0%) than those from White women (68.5%) (*P ≤ 0.05). RNA-sequencing analysis in myometrium revealed differentially expressed genes (270 upregulated, 374 downregulated) dependent on race, wherein reactive oxygen species, hypoxia, and oxidative phosphorylation pathways were positively correlated with samples derived from Black patients. The levels of proteins associated with oxidative DNA damage and repair, 8-hydroxyguanosine (8-OHdG), 8-oxoguanine glycosylase (OGG1), heme oxygenase-1 (HO-1), and kelch-like ECH-associated protein 1 (KEAP1), were higher in leiomyoma and matched myometrium, particularly those from Black patients, compared to the control myometrium (with leiomyoma) (***P ≤ 0.001). LARGE SCALE DATA: The datasets are available in the NCBI (The BioProject number: PRJNA859428). LIMITATIONS, REASONS FOR CAUTION: Myometrium without leiomyoma derived from White patients was used as a control in the tissue microarray analysis, as myometrium without leiomyoma from Black patients was not accessible in large numbers. The RNA sequencing was performed on myometrium tissue with leiomyoma present from 10 White and 10 Black women. However, one sample from a Black woman yielded low-quality RNA-sequencing data and was excluded from further analysis. WIDER IMPLICATIONS OF THE FINDINGS: Women with symptomatic leiomyomas have a considerable loss in their quality of life. This study provides information on underlying genetic and molecular defects that may be necessary for future therapeutics targeted at leiomyomas. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by grants from NCI (R01CA254367) and NICHD (P01HD057877). The authors declare no conflict of interest.

Primary HPV-Associated Enteric-Type Adenocarcinoma of Vagina: A Case Report.

Primary enteric type adenocarcinomas of the vagina are extremely rare. We present a 63-year-old woman who had a polypoid mass localized to the distal vagina. The lesion was composed of a columnar glandular cell proliferation with focal cribriforming, reminiscent of tubular adenoma. Immunohistochemical stains were notable for expression of enteric markers (CDX2 and KRT20), as well as negativity for Mullerian markers (PAX8, ER, and PR), diffuse expression for p16, and positivity for high-risk HPV mRNA expression. Ultimately, a diagnosis of vaginal primary HPV-associated enteric type adenocarcinoma was rendered for this unusual lesion. To our knowledge, no prior cases of HPV-associated enteric type adenocarcinomas of the vagina have been described before.

Loss of dystrophin is common in uterine leiomyosarcoma: a potential biomarker for clinical application.

Uterine leiomyosarcoma (LMS) is a deadly disease with high rates of recurrence and a poor prognosis. Its tumorigenesis remains largely unknown, and no specific biomarkers can be used for the differential diagnosis of LMS from other mimics. Recent whole-genome studies revealed a loss of dystrophin is common in LMS, especially in uterine LMS. To investigate the expression pattern of dystrophin expression across different types of uterine smooth muscle tumors, immunohistochemistry was performed, including usual-type leiomyoma, fumarate hydratase-deficient leiomyoma, leiomyoma with bizarre nuclei, conventional LMS, and normal myometrium for this study. To further evaluate the genomic change in dystrophin gene region, whole-genome sequencing in 10 LMS cases were analyzed. Dystrophin expression was detected in 94% (45/48) of myometrium, 97% (34/35) of usual-type leiomyoma, 84% (26/31) of fumarate hydratase-deficient leiomyoma, 60% (12/20) of leiomyoma with bizarre nuclei, and 18% (6/34) of LMS. Loss of dystrophin expression was significantly different between benign and malignant tumors (LMS cases counted as malignant only) (p < 0.01). Of note, copy number loss in the dystrophin genomic region was found in all 10 cases of LMS. Additionally, patients with dystrophin-positive LMS tend to have a better overall survival than patients with dystrophin-negative LMS.

Telepathology in Nigeria for Global Health Collaboration.

Inadequate pathology personnel and high cost of running a Pathology facility are factors affecting access to timely and quality pathology services in resource-constrained settings. Telepathology is a novel technology that allows Pathologists to remotely assess collected samples. Though the initial cost of setting up a telepathology facility is high, its overall benefits far outweigh the cost. Its usefulness as a quality assurance measure, as a permanent image data storage system, in reducing costs associated with repeated slide preparations, reducing turn-around time of pathology reports, in collaborative research and in teaching has been well documented. This paper highlights the experiences, gains and challenges encountered in the deployment of telepathology in two resource-constrained settings in Nigeria. Overcoming the challenges associated with setting up a telepathology service in sub-Saharan Africa is important as it has the potential to improve overall health outcomes in a medically underserved region while ensuring technology and knowledge transfer are achieved.

Ovarian cancer cell fate regulation by the dynamics between saturated and unsaturated fatty acids.

Fatty acids are an important source of energy and a key component of phospholipids in membranes and organelles. Saturated fatty acids (SFAs) are converted into unsaturated fatty acids (UFAs) by stearoyl Co-A desaturase (SCD), an enzyme active in cancer. Here, we studied how the dynamics between SFAs and UFAs regulated by SCD impacts ovarian cancer cell survival and tumor progression. SCD depletion or inhibition caused lower levels of UFAs vs. SFAs and altered fatty acyl chain plasticity, as demonstrated by lipidomics and stimulated Raman scattering (SRS) microscopy. Further, increased levels of SFAs resulting from SCD knockdown triggered endoplasmic reticulum (ER) stress response with brisk activation of IRE1α/XBP1 and PERK/eIF2α/ATF4 axes. Disorganized ER membrane was visualized by electron microscopy and SRS imaging in ovarian cancer cells in which SCD was knocked down. The induction of long-term mild ER stress or short-time severe ER stress by the increased levels of SFAs and loss of UFAs led to cell death. However, ER stress and apoptosis could be readily rescued by supplementation with UFAs and reequilibration of SFA/UFA levels. The effects of SCD knockdown or inhibition observed in vitro translated into suppression of intraperitoneal tumor growth in ovarian cancer xenograft models. Furthermore, a combined intervention using an SCD inhibitor and an SFA-enriched diet initiated ER stress in tumors growing in vivo and potently blocked their dissemination. In all, our data support SCD as a key regulator of the cancer cell fate under metabolic stress and point to treatment strategies targeting the lipid balance.

Histological and molecular analysis of cellular leiomyoma with sclerosis: linked to HMGA2 overexpression.

HMGA2 overexpression is found in 10-15% of leiomyomas (LM). HMGA2 overexpression is common in variants of hydropic, intravenous and lipo-LM. Cellular or highly cellular LM (CLM) is a LM variant with a less well-defined molecular nature. In this study, we identified and examined 52 hypercellular LM with sclerotic collagen, herein defined as cellular leiomyoma with sclerosis (CLM-S). CLM-S shows large tumour size (average 12.2 cm) and characteristic histology of tumour cells, arranged in cellular fascicles, sheets and trabeculae with abundant dense, pink sclerotic extracellular matrix in bands and nodules and increased vascularity. Tumour cells are uniform with small, round-oval nuclei and scant, pale-eosinophilic to vacuolated cytoplasm reminiscent of pericytes. The differential diagnosis of CLM-S includes conventional CLM, endometrial stromal tumours and perivascular epithelioid cell tumour. Immunohistochemical profile [HMGA2, fumarate hydratase, smooth muscle markers, Melan A and HMB-45] and molecular alterations [by HMGA2 mRNA reverse transcription-polymerase chain reaction (RT-PCR), HMGA2 fluorescence in-situ hybridisation and MED12 sequencing] were analysed in comparison to matched myometrium and CLM controls. Remarkably, 96% (50 of 52) of CLM-S demonstrated diffuse positive immunoreactivity for HMGA2 and up to an 80-fold increase in HMGA2 mRNA, determined by RT-PCR. FISH analysis with break-part probes at intron 3 and the 5' UTR detected HMGA2 rearrangements in 47% (18 of 38) of CLM-S. All CLM-S retained expression of fumarate hydratase. No MED12 mutations were found in any CLM-S. Our findings show that CLM-S has unique and characteristic histomorphology probably driven by HMGA2 overexpression.

Single-cell sequencing reveals novel cellular heterogeneity in uterine leiomyomas.

STUDY QUESTION: What are the cellular composition and single-cell transcriptomic differences between myometrium and leiomyomas as defined by single-cell RNA sequencing? SUMMARY ANSWER: We discovered cellular heterogeneity in smooth muscle cells (SMCs), fibroblast and endothelial cell populations in both myometrium and leiomyoma tissues. WHAT IS KNOWN ALREADY: Previous studies have shown the presence of SMCs, fibroblasts, endothelial cells and immune cells in myometrium and leiomyomas. However, there is no information on the cellular heterogeneity in these tissues and the transcriptomic differences at the single-cell level between these tissues. STUDY DESIGN, SIZE, DURATION: We collected five leiomyoma and five myometrium samples from a total of eight patients undergoing hysterectomy. We then performed single-cell RNA sequencing to generate a cell atlas for both tissues. We utilized our single-cell sequencing data to define cell types, compare cell types by tissue type (leiomyoma versus myometrium) and determine the transcriptional changes at a single-cell resolution between leiomyomas and myometrium. Additionally, we performed MED12-variant analysis at the single-cell level to determine the genotype heterogeneity within leiomyomas. PARTICIPANTS/MATERIALS, SETTING, METHODS: We collected five MED12-variant positive leiomyomas and five myometrium samples from a total of eight patients. We then performed single-cell RNA sequencing on freshly isolated single-cell preparations. Histopathological assessment confirmed the identity of the samples. Sanger sequencing was performed to confirm the presence of the MED12 variant in leiomyomas. MAIN RESULTS AND ROLE OF CHANCE: Our data revealed previously unknown heterogeneity in the SMC, fibroblast cell and endothelial cell populations of myometrium and leiomyomas. We discovered the presence of two different lymphatic endothelial cell populations specific to uterine leiomyomas. We showed that both myometrium and MED12-variant leiomyomas are relatively similar in cellular composition but differ in cellular transcriptomic profiles. We found that fibroblasts influence the leiomyoma microenvironment through their interactions with endothelial cells, immune cells and SMCs. Variant analysis at the single-cell level revealed the presence of both MED12 variants as well as the wild-type MED12 allele in SMCs of leiomyomatous tissue. These results indicate genotype heterogeneity of cellular composition within leiomyomas. LARGE SCALE DATA: The datasets are available in the NCBI Gene Expression Omnibus (GEO) using GSE162122. LIMITATIONS, REASONS FOR CAUTION: Our study focused on MED12-variant positive leiomyomas for single-cell RNA sequencing analyses. Leiomyomas carrying other genetic rearrangements may differ in their cellular composition and transcriptomic profiles. WIDER IMPLICATIONS FOR THE FINDINGS: Our study provides a cellular atlas for myometrium and MED12-variant positive leiomyomas as defined by single-cell RNA sequencing. Our analysis provides significant insight into the differences between myometrium and leiomyomas at the single-cell level and reveals hitherto unknown genetic heterogeneity in multiple cell types within human leiomyomas. Our results will be important for future studies into the origin and growth of human leiomyomas. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by funding from the National Institute of Child Health and Human Development (HD098580 and HD088629). The authors declare no competing interests.