Primordial germ cells as a potential shared cell of origin for mucinous cystic neoplasms of the pancreas and mucinous ovarian tumors

Clonal expansion of intra-epithelial T cells in breast cancer revealed by spatial transcriptomics

The spatial distribution of tumor-infiltrating lymphocytes (TIL) predicts breast cancer outcome and response to systemic therapy, highlighting the importance of an intact tissue structure for characterizing tumors. Here, we present ST-FFPE, a spatial transcriptomics method for the analysis of formalin-fixed paraffin-embedded samples, which opens the possibility of interrogating archival tissue. The method involves extraction, exome capture and sequencing of RNA from different tumor compartments microdissected by laser-capture, and can be used to study the cellular composition of tumor microenvironment. Focusing on triple-negative breast cancer (TNBC), we characterized T cells, B cells, dendritic cells, fibroblasts and endothelial cells in both stromal and intra-epithelial compartments. We found a highly variable spatial distribution of immune cell subsets among tumors. This analysis revealed that the immune repertoires of intra-epithelial T and B cells were consistently less diverse and more clonal than those of stromal T and B cells. T-cell receptor (TCR) sequencing confirmed a reduced diversity and higher clonality of intra-epithelial T cells relative to the corresponding stromal T cells. Analysis of the top 10 dominant clonotypes in the two compartments showed a majority of shared but also some unique clonotypes both in stromal and intra-epithelial T cells. Hyperexpanded clonotypes were more abundant among intra-epithelial than stromal T cells. These findings validate the ST-FFPE method and suggest an accumulation of antigen-specific T cells within tumor core. Because ST-FFPE is applicable for analysis of previously collected tissue samples, it could be useful for rapid assessment of intratumoral cellular heterogeneity in multiple disease and treatment settings.

Primary Retroperitoneal Carcinomas: New Insights into Pathogenesis and Clinical Management in Comparison with Ovarian Carcinomas and Carcinoma of Unknown Primary

Primary retroperitoneal carcinomas are very rare tumors. Their pathogenesis remains unknown but may be associated with that of ovarian carcinomas, considering the similarity in morphology and gender preference. Although metaplasia of coelomic epithelium is the most widely accepted theory, the pathogenesis of retroperitoneal carcinomas may differ by histologic subtype, like ovarian carcinomas. Mucinous carcinoma, which develops in both women and men, may originate in both primordial germ cells and Walthard cell nests that may be derived from the fallopian tube. Serous carcinomas may be associated with endosalpingiosis, the presence of fallopian tube-like epithelium outside the fallopian tube, and a remnant Müllerian tract. Endometrioid and clear cell carcinomas appear to be associated with extraovarian endometriosis. Additionally, both carcinomas in the retroperitoneal lymph nodes may be metastatic diseases from endometrial and/or renal cell cancer that regress spontaneously (carcinoma of unknown primary). Retroperitoneal carcinomas are difficult to diagnose, as they have no characteristic symptoms and signs. Surgery is the cornerstone of treatment, but the necessity of chemotherapy may depend on histological subtype. Further studies are necessary, in particular studies on endosalpingiosis, as endosalpingiosis is a poorly understood condition, although it is associated with the development of both serous and mucinous carcinomas.

Rare Epithelial Ovarian Cancers: Low Grade Serous and Mucinous Carcinomas

The ovarian epithelial cancer histotypes can be divided into common and rare types. Common types include high-grade serous ovarian carcinomas and the endometriosis-associated cancers, endometrioid and clear-cell carcinomas. The less common histotypes are mucinous and low-grade serous, each comprising less than 10% of all epithelial carcinomas. Although histologically and epidemiologically distinct from each other, these histotypes share some genetic and natural history features that distinguish them from the more common types. In this review, we will consider the similarities and differences of these rare histological types, and the clinical challenges they pose.

Identification of high-risk features in mucinous cystic neoplasms of the pancreas

BACKGROUND

Mucinous cystic neoplasms of the pancreas are uncommon tumors that have the potential of becoming cancer. There is no consensus regarding the high-risk features of these tumors. Our study aimed to identify the preoperative demographic, clinical, or radiologic factors that can predict the presence of high-grade dysplasia or invasive carcinoma in mucinous cystic neoplasms of the pancreas.

METHODS

We identified 157 patients who underwent resection and fulfilled the pathologic criteria for mucinous cystic neoplasms of the pancreas in a prospectively maintained database spanning 3 decades (1990-2020). Multivariable logistic regression was used to identify predictors of high-grade dysplasia or invasive carcinoma in mucinous cystic neoplasms of the pancreas.

RESULTS

The rate of high-grade dysplasia or invasive carcinoma was 11%. Tumor size ≥4 cm (P < .001), mural nodularity (P = .04), and a serum CA 19-9 level >37 U/mL (P < .001) were associated with high-grade dysplasia or invasive carcinoma. In the multivariable analysis, tumor size ≥4 cm (odds ratio 16.9, 95% confidence interval 2.04-140, P = .009) and a CA 19-9 level >37 U/mL (odds ratio 5.68, 95% confidence interval 1.52-21.3, P = .010) were predictors of high-grade dysplasia or invasive carcinoma. There were no tumors with high-grade dysplasia or invasive carcinoma in patients with tumor size <4 cm in the absence of an elevated CA 19-9 or mural nodularity.

CONCLUSION

Tumors with a size ≥4 cm and/or a high CA 19-9 level should be considered for prompt surgical resection. Conversely, tumors <4 cm with no other high-risk features have a negligible risk for high-grade dysplasia or invasive carcinoma and may benefit from nonoperative surveillance. Mural nodularity is an additional suspicious feature. These findings may contribute to future guidelines.

Germline stem cells in human

The germline cells are essential for the propagation of human beings, thus essential for the survival of mankind. The germline stem cells, as a unique cell type, generate various states of germ stem cells and then differentiate into specialized cells, spermatozoa and ova, for producing offspring, while self-renew to generate more stem cells. Abnormal development of germline stem cells often causes severe diseases in humans, including infertility and cancer. Primordial germ cells (PGCs) first emerge during early embryonic development, migrate into the gentile ridge, and then join in the formation of gonads. In males, they differentiate into spermatogonial stem cells, which give rise to spermatozoa via meiosis from the onset of puberty, while in females, the female germline stem cells (FGSCs) retain stemness in the ovary and initiate meiosis to generate oocytes. Primordial germ cell-like cells (PGCLCs) can be induced in vitro from embryonic stem cells or induced pluripotent stem cells. In this review, we focus on current advances in these embryonic and adult germline stem cells, and the induced PGCLCs in humans, provide an overview of molecular mechanisms underlying the development and differentiation of the germline stem cells and outline their physiological functions, pathological implications, and clinical applications.

Intralobular distribution of ovarian-like stroma in pancreatic mucinous cystic neoplasms: a discussion on its tumorigenesis

Pancreatic mucinous cystic neoplasm (MCN) has two histological components: tumor epithelia and ovarian-like stroma (OLS). To examine the progression and changes in pancreatic MCNs, we analyzed the distribution, amount, immunohistochemical phenotype, presence of theca cells of OLS, and tumor epithelium in 45 surgically resected MCN cases, comparing them with tumor sizes. The OLS data of female MCN cases were also compared between those who were ≤ 51 years old and those > 51 years old to see the effect of menopause on MCN histology. Non-mucinous type epithelium was present in all low-grade MCNs, but its ratio decreased with tumor size (p < 0.001), suggesting that epithelial mucinous changes are a progression phenomenon. The intralobular distribution of OLS was observed in 28.8% of MCN cases and was related to smaller tumor size (p < 0.0001), suggesting intralobular involvement of early MCNs. The nuclear expression of β-catenin and the cytoplasmic expression of α-smooth muscle actin (SMA) was observed in almost all OLS. OLS tended to be lesser among female cases aged > 51 years than those ≤ 51 years old, however it did not reach statistical significance. This is the first study to show the intralobular distribution of OLS.

Müllerian Mucinous Cystadenomas of the Ovary: A Report of 25 Cases of an Unheralded Benign Ovarian Neoplasm Often Associated With Endometriosis and a Brief Consideration of Neoplasms Arising From the Latter

A subset of ovarian mucinous tumors demonstrates müllerian-type epithelium, with such lesions variably designated "endocervical-like" and seromucinous since their popularization based on a report of borderline examples in 1989. While müllerian mucinous borderline tumors and carcinomas have been highlighted in the literature, there has been minimal attention given to benign müllerian mucinous tumors, particularly müllerian mucinous cystadenomas. Given the paucity of literature describing the features of müllerian mucinous cystadenomas/cystadenofibromas, diagnostic difficulties may arise when papillary features are present and in cases that show a subtle transition from endometriosis. We thus reviewed 25 cases of müllerian mucinous cystadenoma/cystadenofibroma to highlight the notable characteristics of this entity, including gross, cytologic, and architectural features that aid in the distinction from müllerian mucinous borderline tumors as well as, rarely, metastatic tumors. The patients ranged in age from 26 to 85 yr old. Bilateral ovarian involvement was frequent (40%). The ovaries ranged from 2.3 to 26 cm in greatest dimension. Most were multicystic (18 cases) and contained tenacious mucoid material (14 cases). All cases demonstrated predominantly columnar mucinous epithelium with abundant pale-pink cytoplasm. A minor component of ciliated and endometrioid epithelium was seen in 15 and 2 cases, respectively. Broad papillary formations were frequently encountered (9 cases) as was epithelial papillary tufting comprising <10% of the tumor (6 cases). Endometriosis was present in 9 cases, with a transition from endometriosis to mucinous epithelium noted in 8 cases. This series highlights the morphologic features of a relatively uncommon, benign, endometriosis-associated ovarian tumor that may be confused with a müllerian mucinous borderline tumor or bland metastatic mucinous tumors. It also provides an argument for the terminology "müllerian mucinous cystadenoma" or "cystadenofibroma" rather than "seromucinous cystadenoma" due to the frequent association with endometriosis as well as the dominant mucinous epithelium.

Early detection of pancreatic cancer using DNA-based molecular approaches

Due to its poor prognosis and the late stage at which it is typically diagnosed, early detection of pancreatic cancer is a pressing clinical problem. Advances in genomic analysis of human pancreatic tissue and other biospecimens such as pancreatic cyst fluid, pancreatic juice and blood have opened the possibility of DNA-based molecular approaches for early detection of pancreatic cancer. In this Review, we discuss and focus on the pathological and molecular features of precancerous lesions of the pancreas, including pancreatic intraepithelial neoplasia, intraductal papillary mucinous neoplasm and mucinous cystic neoplasm, which are target lesions of early detection approaches. We also discuss the most prevalent genetic alterations in these precancerous lesions, including somatic mutations in the oncogenes KRAS and GNAS as well as tumour suppressor genes CDKN2A, TP53 and SMAD4. We highlight the latest discoveries related to genetic heterogeneity and multifocal neoplasia in precancerous lesions. In addition, we review specific approaches, challenges and clinically available assays for early detection of pancreatic cancer using DNA-based molecular techniques. Although detection and risk stratification of precancerous pancreatic neoplasms are difficult problems, progress in this field highlights the promise of molecular approaches for improving survival of patients with this disease.

To Be or Not to Be a Germ Cell: The Extragonadal Germ Cell Tumor Paradigm

In the human embryo, the genetic program that orchestrates germ cell specification involves the activation of epigenetic and transcriptional mechanisms that make the germline a unique cell population continuously poised between germness and pluripotency. Germ cell tumors, neoplasias originating from fetal or neonatal germ cells, maintain such dichotomy and can adopt either pluripotent features (embryonal carcinomas) or germness features (seminomas) with a wide range of phenotypes in between these histotypes. Here, we review the basic concepts of cell specification, migration and gonadal colonization of human primordial germ cells (hPGCs) highlighting the analogies of transcriptional/epigenetic programs between these two cell types.

High-Risk Characteristics Associated with Advanced Pancreatic Cystic Lesions: Results from a Retrospective Surgical Cohort

BACKGROUND AND AIM

The management of pancreatic cystic lesions (PCLs) remains controversial. We performed a retrospective study to determine characteristics associated with advanced PCLs (A-PCLs) and whether these characteristics vary in different pathological types of PCLs. The additional diagnostic value of endoscopic ultrasound (EUS) was also evaluated.

METHODS

Patients who underwent surgical resection for an identified PCLs by imaging modalities were included. A logistic regression model was developed to identify significant characteristics for A-PCLs. EUS data was assessed separately.

RESULTS

Three hundred and fifty-three patients were included, and 125 patients (35.4%) were A-PCLs. The presence of main pancreatic duct (MPD) diameter ≥ 10 mm (odds ratio [OR], 11.7; 95% confidence interval [CI], 1.53-89.2; P = 0.018), mural nodules ≥ 5 mm (OR, 11.67; 95% CI, 2.3-59.05; P = 0.003), solid components within cysts (OR, 30.87; 95% CI, 7.23-131.7; P < 0.0001) and high serum CA19-9 levels (OR, 1.006; 95% CI, 1.001-1.011; P = 0.02) were independently associated with the presence of A-PCLs. The presence of septa was independently associated with the presence of non-A-PCLs (OR, 0.147; 95% CI, 0.04-0.6; P = 0.008). Males who had a history of tobacco abuse (P < 0.0001) and had a greatly dilated MPD (P < 0.0001) were more common in advanced intraductal papillary mucinous neoplasms (IPMC) patients. Solid pseudopapillary neoplasm (SPT) often occurred in young women (P < 0.0001), mostly asymptomatically (P < 0.0001) and with lower serum CA19-9 levels (P < 0.0001). In the 124 patients who underwent EUS-guided fine-needle aspiration (EUS-FNA), five additional characteristics (4 mural nodules and 1 MPD involvement) were identified by EUS imaging and 17 patients were identified with abnormal cytological results (13 atypical cells and 4 suspicious for malignancy cells) by EUS-FNA.

CONCLUSION

On the basis of a retrospective study with large sample size, the presence of MPD ≥ 10 mm, mural nodules, solid components, and high serum CA19-9 levels were independently associated with the presence of A-PCLs. The high-risk characteristics may vary across different types of A-PCLs. EUS and EUS-FNA could provide additional diagnostic information for PCLs.

Mesenteric and Retroperitoneal Mucinous Cystic Neoplasms: A Case Series

Aims. Mucinous cystic neoplasms (MCNs) are cystic neoplasms with mucinous epithelium surrounded by ovarian-like stroma. Extraovarian MCN occurring in the liver and pancreas have been well characterized. However, only rare case reports of MCN arising outside of these locations have been reported. MCNs arising in unusual locations should enter the differential diagnosis of mucinous intra-abdominal tumors and must be distinguished from more common mimics. Therefore, we aimed to examine a series of MCNs of the retroperitoneum and mesentery to characterize the clinicopathologic features of this entity. Methods and results. Seven MCNs arising in the abdominal mesentery or retroperitoneum were retrospectively identified. A clinicopathologic, histologic, and immunohistochemical (keratin 7, keratin 19, keratin 20, calretinin, inhibin-α, steroidogenic factor-1 (SF-1), estrogen receptor (ER), progesterone receptor (PR), PAX8, CDX2, and CD10) analysis was performed. All 7 MCNs were from females with a median age of 41 years old and a median size of 8 cm. All cases demonstrated mucinous with or without concomitant non-mucinous epithelium overlying spindle cell ovarian-like stroma. Luteinized cells were noted. The epithelium was positive for keratin 7 and keratin 19 in all 7 cases, while the stroma expressed ER, PR, and SF-1 in all cases stained. Calretinin was focally positive in the stroma of 3 of 7 cases, while inhibin-α was focally expressed in 5 of 6 cases. Conclusions. These results highlight the clinicopathologic, histologic, and immunophenotypic similarities between MCNs of the mesentery, retroperitoneum, pancreas, and liver. Overlapping features suggest a common histogenesis for all MCNs, which could include periductal fetal mesenchyme, aberrant migration of primordial germ cells, or abnormal differentiation or metaplasia of the embryonic coelomic epithelium.

Validation of serum tumor biomarkers in predicting advanced cystic mucinous neoplasm of the pancreas

BACKGROUND

Early detection of advanced cystic mucinous neoplasms [(A-cMNs), defined as high-grade dysplasia or malignancy] of the pancreas is of great significance. As a simple and feasible detection method, serum tumor markers (STMs) may be used to predict advanced intraductal papillary mucinous neoplasms (IPMNs) and mucinous cystic neoplasms (MCNs). However, there are few studies on the usefulness of STMs other than carbohydrate antigen (CA) 19-9 for early detection of A-cMNs.

AIM

To study the ability of five STMs-CA19-9, carcinoembryonic antigen (CEA), CA125, CA724, and CA242 to predict A-cMNs and distinguish IPMNs and MCNs.

METHODS

We mainly measured the levels of each STM in patients pathologically diagnosed with cMNs. The mean levels of STMs and the number of A-cMN subjects with a higher STM level than the cutoff were compared respectively to identify the ability of STMs to predict A-cMNs and distinguish MCNs from IPMNs. A receiver operating characteristic curve with the area under curve (AUC) was also created to identify the performance of the five STMs.

RESULTS

A total of 187 patients with cMNs were identified and 72 of them showed A-cMNs. We found that CA19-9 exhibited the highest sensitivity (SE) (54.2%) and accuracy (76.5%) and a moderate ability (AUC = 0.766) to predict A-cMNs. In predicting high-grade dysplasia IPMNs, the SE of CA19-9 decreased to 38.5%. The ability of CEA, CA125, and CA724 to predict A-cMNs was low (AUC = 0.651, 0.583, and 0.618, respectively). The predictive ability of CA242 was not identified. The combination of STMs improved the SE to 62.5%. CA125 may be specific to the diagnosis of advanced MCNs.

CONCLUSION

CA19-9 has a moderate ability, and CEA, CA125, and CA724 have a low ability to predict A-cMNs. The combination of STM testing could improve SE in predicting A-cMNs.

IIyas S, Smoot RL, Liu Y, Davila J, Graham RP. Molecular and Immunohistochemical Analysis of Mucinous Cystic Neoplasm of the Liver

OBJECTIVES

Mucinous cystic neoplasm of the liver is characterized by neoplastic mucinous and/or biliary epithelium surrounded by ovarian-type stroma. Immunohistochemical studies have shown that the ovarian-type stroma expresses estrogen receptor, suggesting potential hormonal responsiveness. The molecular biology of mucinous cystic neoplasm of the liver remains poorly studied.

METHODS

Transcriptome sequencing and immunohistochemistry were performed on a series of mucinous cystic neoplasms.

RESULTS

Mucinous cystic neoplasm of the liver exhibited significantly increased RNA expression of ovarian stromal markers WT1, PR, and ER2 and sex cord stromal markers SF-1, inhibin-α, and calretinin compared with nonneoplastic liver. Immunohistochemistry confirmed the RNA-level data. Evidence for sex hormone biosynthesis was identified by significant overexpression of multiple estrogen biosynthetic enzymes. Expression of 17β-hydroxysteroid dehydrogenase 1 was confirmed immunohistochemically. Pathway analysis also identified significant upregulation of the hedgehog and Wnt pathways and significant downregulation of T-helper 1 and T-helper 2 pathways.

CONCLUSIONS

Mucinous cystic neoplasm of the liver recapitulates ovarian stroma at the morphologic, DNA, RNA, and protein levels. These data support the concept that this tumor likely arises from ectopic primitive gonadal tissue and/or stromal cells with capacity to transdifferentiate to ovarian cortical cells.

Transcription factors in epithelial ovarian cancer: histotype-specific drivers and novel therapeutic targets

Transcription factors (TFs) are major contributors to cancer risk and somatic development. In preclinical and clinical studies, direct or indirect inhibition of TF-mediated oncogenic gene expression profiles have proven to be effective in many tumor types, highlighting this group of proteins as valuable therapeutic targets. In spite of this, our understanding of TFs in epithelial ovarian cancer (EOC) is relatively limited. EOC is a heterogeneous disease composed of five major histologic subtypes; high-grade serous, low-grade serous, endometrioid, clear cell and mucinous. Each histology is associated with unique clinical etiologies, sensitivity to therapies, and molecular signatures - including diverse transcriptional regulatory programs. While some TFs are shared across EOC subtypes, a set of TFs are expressed in a histotype-specific manner and likely explain part of the histologic diversity of EOC subtypes. Targeting TFs present with unique opportunities for development of novel precision medicine strategies for ovarian cancer. This article reviews the critical TFs in EOC subtypes and highlights the potential of exploiting TFs as biomarkers and therapeutic targets.

The cellular origins of cancer with particular reference to the gastrointestinal tract

Stem cells or their closely related committed progenitor cells are the likely founder cells of most neoplasms. In the continually renewing and hierarchically organized epithelia of the oesophagus, stomach and intestine, homeostatic stem cells are located at the beginning of the cell flux, in the basal layer of the oesophagus, the isthmic region of gastric oxyntic glands and at the bottom of gastric pyloric-antral glands and colonic crypts. The introduction of mutant oncogenes such as Kras^G12D or loss of Tp53 or Apc to specific cell types expressing the likes of Lgr5 and Mist1 can be readily accomplished in genetically engineered mouse models to initiate tumorigenesis. Other origins of cancer are discussed including 'reserve' stem cells that may be activated by damage or through disruption of morphogen gradients along the crypt axis. In the liver and pancreas, with little cell turnover and no obvious stem cell markers, the importance of regenerative hyperplasia associated with chronic inflammation to tumour initiation is vividly apparent, though inflammatory conditions in the renewing populations are also permissive for tumour induction. In the liver, hepatocytes, biliary epithelial cells and hepatic progenitor cells are embryologically related, and all can give rise to hepatocellular carcinoma and cholangiocarcinoma. In the exocrine pancreas, both acinar and ductal cells can give rise to pancreatic ductal adenocarcinoma (PDAC), although the preceding preneoplastic states are quite different: acinar-ductal metaplasia gives rise to pancreatic intraepithelial neoplasia culminating in PDAC, while ducts give rise to PDAC via. mucinous cell metaplasia that may have a polyclonal origin.

Non-coding somatic mutations converge on the PAX8 pathway in ovarian cancer

The functional consequences of somatic non-coding mutations in ovarian cancer (OC) are unknown. To identify regulatory elements (RE) and genes perturbed by acquired non-coding variants, here we establish epigenomic and transcriptomic landscapes of primary OCs using H3K27ac ChIP-seq and RNA-seq, and then integrate these with whole genome sequencing data from 232 OCs. We identify 25 frequently mutated regulatory elements, including an enhancer at 6p22.1 which associates with differential expression of ZSCAN16 (P = 6.6 × 10-4) and ZSCAN12 (P = 0.02). CRISPR/Cas9 knockout of this enhancer induces downregulation of both genes. Globally, there is an enrichment of single nucleotide variants in active binding sites for TEAD4 (P = 6 × 10-11) and its binding partner PAX8 (P = 2×10-10), a known lineage-specific transcription factor in OC. In addition, the collection of cis REs associated with PAX8 comprise the most frequently mutated set of enhancers in OC (P = 0.003). These data indicate that non-coding somatic mutations disrupt the PAX8 transcriptional network during OC development.

The tubal epigenome - An emerging target for ovarian cancer

Ovarian cancer is the most lethal gynecologic malignancy in the United States. The mortality of this disease is primarily attributed to challenges in early detection and therapeutic resistance. Recent studies indicate that the majority of high-grade serous ovarian carcinomas (HGSCs) originate from aberrant fallopian tube epithelial (FTE) cells. This shift in thinking about ovarian cancer pathogenesis has been met with an effort to identify the early genetic and epigenetic changes that underlie the transformation of normal FTE cells and prompt them to migrate and colonize the ovary, ultimately giving rise to aggressive HGSC. While identification of these early changes is important for biomarker discovery, the emergence of epigenetic alterations in FTE chromatin may also provide new opportunities for early detection, prevention, and therapeutic intervention. Here we provide a comprehensive overview of the current knowledge regarding early epigenetic reprogramming that precedes HGSC tumor development, the way that these alterations affect both intrinsic and extrinsic tumor properties, and how the epigenome may be targeted to thwart HGSC tumorigenesis.

Mucinous Ovarian Tumors

Ovarian mucinous tumors range from benign cystadenomas to borderline tumors to frankly malignant adenocarcinomas, and may display either intestinal-type morphology or, less frequently, endocervical-type differentiation. The latter category has been the subject of recent controversy owing to its morphologic overlap with so-called "seromucinous" ovarian tumors, a group that shares more molecular features with endometrioid tumors than it does with either serous or mucinous ovarian neoplasias. Endocervical-type differentiation in ovarian mucinous tumors may also represent an endocervical metastasis. Distinction of primary ovarian mucinous tumors from gastrointestinal metastases can be difficult, as the morphology of intestinal-type ovarian mucinous primaries sometimes differs only subtly if at all from gastrointestinal metastases.