Pathogenesis of Testicular Germ Cell Tumors from a Developmental Point of View

Current classification systems of human germ cell tumors (GCTs) are based on histological composition. In the group of nonseminomas, different variants of teratoma (somatic differentiation), yolk sac tumor and choriocarcinoma (extra-embryonic differentiation), are recognized, as well as their stem cell component embryonal carcinoma. In addition, the seminomatous tumors are distinguished, subdivided into classic - and spermatocytic variants. The morphologically similar classic seminomas of the ovary are called dysgerminomas, and those of the brain germinomas. Tumors containing both a (classic) seminoma and a nonseminoma component are referred to as combined tumor according to the British classification , and as nonseminoma in the World Health Organisation (WHO) Classification. This traditional histological description obscures the biological diversity of this type of cancer, which hampers identification of pathogenetic mechanisms and proper comparison of the neoplastic cells to their normal counterparts. Therefore, an alternative classification was proposed, recognizing five categories (I-V) of GCTs (see Table 1), based on site of presentation, age of the patient at diagnosis, histological composition, as well as pattern of genomic imprinting, and chromosomal constitution. This thesis will deal only with the type II GCTs, predominantly of the testis, and therefore the other types will not be discussed here. The testicular type II GCTs will be referred as TGCTs

Use of immunohistochemical biomarkers as independent predictor of neoplastic progression in Barrett's oesophagus surveillance

__Introduction:__ The low incidence of oesophageal adenocarcinoma (EAC) in Barrett's oesophagus (BE) patients reinforces the need for risk stratification tools to make BE surveillance more effective. Therefore, we have undertaken a systematic revi

MTOR is a promising therapeutical target in a subpopulation of pancreatic adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) remains a highly lethal disease, unusually resistant against therapy. It is generally felt that stratification of patients for personalized medicine is the way forward. Here, we report that a subpopulation of PDACs shows strong activation of the mTOR signaling cassette. Moreover, we show that inhibition of mTOR in pancreatic cancer cell lines showing high levels of mTOR signaling is associated with cancer cell death. Finally, we show using fine needle biopsies the existence of a subpopulation of PDAC patients with high activation of the mTOR signaling cassette and provide evidence that inhibition of mTOR might be clinically useful for this group. Thus, our results define an unrecognized subpopulation of PDACs, characterized by high activation of mTOR and show that identification of this specific patient group in the early phase of diagnosis is feasible

Tumour basement membrane laminin expression predicts outcome following curative resection of pancreatic head cancer

Background: Although widely fragmented BMs have been associated with adverse outcome in several cancer types, comparatively little is known with respect to its effect on the prognosis of pancreatic cancer. The aim of the current study was therefore to determine the prognostic value of tumour basement membrane (BM) continuity in two anatomically closely related, however, prognostically different tumours, pancreatic head-and periampullary cancer. Methods: Tumour BM continuity was determined by immunohistochemical staining of its two major components, laminin and collagen type IV. Associations were made with recurrence free survival (RFS), cancer-specific survival (CSS), overall survival (OS) and conventional prognostic factors. Results: Fifty-nine and 61% of pancreatic head and periampullary tumours, respectively, showed limited BM laminin expression. Whereas 43% and 41% of pancreatic head and periampullary cancers, respectively, showed limited BM collagen type IV expression. Limited BM laminin was associated with poor outcome following curative resection of pancreatic head cancer (P=0.034, 0.013 and 0.017 for RFS, CSS and OS, respectively). Two and a half times as many patients with 25% BM laminin were recurrence free and alive 5 years following resection compared with those with limited BM laminin. Although staining patterns of both BM components were weakly correlated with each other, BM collagen type IV expression was not significantly associated with outcome in either tumour type.Conclusion: Discontinuous BMs, determined by laminin expression, are associated with poor outcome following curative resection of pancreatic head cancer

Early onset esophageal adenocarcinoma: A distinct molecular entity?

Esophageal adenocarcinoma (EAC) is typically diagnosed in elderly with a median age of 68 years. The incidence of EAC has been rising over the last decades, also among young adults. The aim of the study was to investigate whether early onset EAC is a distinct molecular entity. To identify early onset EACs, the nationwide network and registry of histo- and cytopathology in the Netherlands (PALGA) was searched. Twenty-eight tumors of patients aged ≤40 years were selected and matched with 27 tumors of patients aged =68 years. DNA was isolated from surgically resected specimen and sequenced on the Ion Torrent Personal Genome Machine with the Ion AmpliSeq Cancer Panel. No differences in mutational load between early onset and conventional EACs were observed (P=0.196). The most frequently mutated genes were TP53 (73%) and P16 (16%). Additional mutations in early onset EACs occurred exclusively in: APC, CDH1, CTNNB1, FGFR2, and STK11. In the conventional EACs additional mutations were exclusively identified in: ABL1, FBXW7, GNA11, GNAS, KRAS, MET, SMAD4, and VHL. Additional mutations besides TP53 and P16 seem to occur in different genes related to cell fate pathways for early onset EACs, while the additional mutations in conventional EACs are related to survival pathways

External Validation of Pretreatment Pathological Tumor Extent in Patients with Neoadjuvant Chemoradiotherapy Plus Surgery for Esophageal Cancer

Background: This study was conducted to validate a pretreatment (i.e. prior to neoadjuvant chemoradiotherapy) pathological staging system in the resection specimen after neoadjuvant chemoradiotherapy for esophageal cancer. The study investigated the prognostic value of pretreatment pathological T and N categories (prepT and prepN categories) in both an independent and a combined patient cohort. Methods: Patients with esophageal cancer treated with neoadjuvant chemotherapy and esophagectomy between 2012 and 2015 were included. PrepT and prepN categories were estimated based on the extent of tumor regression and regressional changes of lymph nodes in the resection specimen. The difference in Akaike’s information criterion (ΔAIC) was used to assess prognostic performance. PrepN and ypN categories were combined to determine the effect of nodal sterilization on prognosis. A multivariable Cox regression model was used to identify combined prepN and ypN categories as independent prognostic factors. Results: The prognostic strength of the prepT category was better than the cT and ypT categories (ΔAIC 7.7 vs. 3.0 and 2.9, respectively), and the prognostic strength of the prepN category was better than the cN category and similar to the ypN category (ΔAIC 29.2 vs. − 1.0 and 27.9, respectively). PrepN + patients who became ypN0 had significantly worse survival than prepN0 patients (2-year overall survival 69% vs. 86% in 137 patients; p = 0.044). Similar results were found in a combined cohort of 317 patients (2-year overall survival 62% vs. 85%; p = 0.002). Combined prepN/ypN stage was independently associated with overall survival. Conclusions: These results independently confirm the prognostic value of prepTNM staging. PrepTNM staging is of additional prognostic value to cTNM and ypTNM. PrepN0/ypN0 patients have a better survival than prepN +/ypN0 patients

Critical function of AP-2gamma/TCFAP2C in mouse embryonic germ cell maintenance

Formation of the germ cell lineage involves multiple processes, including repression of somatic differentiation and reacquisition of pluripotency as well as a unique epigenetic constitution. The transcriptional regulator Prdm1 has been identified as a main coordinator of this process, controlling epigenetic modification and gene expression. Here we report on the expression pattern of the transcription factor Tcfap2c, a putative downstream target of Prdm1, during normal mouse embryogenesis and the consequences of its specific loss in primordial germ cells (PGCs) and their derivatives. Tcfap2c is expressed in PGCs from Embryonic Day 7.25 (E 7.25) up to E 12.5, and targeted disruption resulted in sterile animals, both male and female. In the mutant animals, PGCs were specified but were lost around E 8.0. PGCs generated in vitro from embryonic stem cells lacking TCFAP2C displayed induction of Prdm1 and Dppa3. Upregulation of Hoxa1, Hoxb1, and T together with lack of expression of germ cell markers such Nanos3, Dazl, and Mutyh suggested that the somatic gene program is induced in TCFAP2C-deficient PGCs. Repression of TCFAP2C in TCam-2, a human PGC-resembling seminoma cell line, resulted in specific upregulation of HOXA1, HOXB1, MYOD1, and HAND1, indicative of mesodermal differentiation. Expression of genes indicative of ectodermal, endodermal, or extraembryonic differentiation, as well as the finding of no change to epigenetic modifications, suggested control by other factors. Our results implicate Tcfap2c as an important effector of Prdml activity that is required for PGC maintenance, most likely mediating Prdm1-induced suppression of mesodermal differentiation

Value of cyclin A immunohistochemistry for cancer risk stratification in Barrett esophagus surveillance A multicenter case-control study

The value of endoscopic Barrett esophagus (BE) surveillance based on histological diagnosis of low-grade dysplasia (LGD) remains debated given the lack of adequate risk stratification. The aim of this study was to evaluate the predictive value of cyclin A expression and to combine these results with our previously reported immunohistochemical p53, AMACR, and SOX2 data, to identify a panel of biomarkers predicting neoplastic progression in BE. We conducted a case–control study within a prospective cohort of 720 BE patients. BE patients who progressed to high-grade dysplasia (HGD, n=37) or esophageal adenocarcinoma (EAC, n=13), defined as neoplastic progression, were classified as cases and patients without neoplastic progression were classified as controls (n=575). Cyclin A expression was determined by immunohistochemistry in all 625 patients; these results were combined with the histological diagnosis and our previous p53, AMACR, and SOX2 data in loglinear regression models. Differences in discriminatory ability were quantified as changes in area under the ROC curve (AUC) for predicting neoplastic progression. Cyclin A surface positivity significantly increased throughout the metaplasia–dysplasia–carcinoma sequences and was seen in 10% (107/1050) of biopsy series without dysplasia, 33% (109/335) in LGD, and 69% (34/50) in HGD/EAC. Positive cyclin A expression was associated with an increased risk of neoplastic progression (adjusted relative risk (RRa) 2.4; 95% CI: 1.7–3.4). Increases in AUC were substantial for P53 (+0.05), smaller for SOX2 (+0.014), minor for cyclin A (+0.003), and none for AMARC (0.00). Cyclin A immunopositivity was associated with an increased progression risk in BE patients. However, compared to p53 and SOX2, the incremental value of cyclin A was limited. The use of biomarkers has the potential to significantly improve risk stratification in BE

Germline variant in MSX1 identified in a Dutch family with clustering of Barrett’s esophagus and esophageal adenocarcinoma

The vast majority of esophageal adenocarcinoma cases are sporadic and caused by somatic mutations. However, over the last decades several families have been identified with clustering of Barrett’s esophagus and esophageal adenocarcinoma. This observation suggests that one or more hereditary factors may play a role in the initiation of Barrett’s esophagus and esophageal adenocarcinoma in these families. A Dutch family with clustering of Barrett’s esophagus and esophageal adenocarcinoma was identified. Normal DNA obtained from the proband diagnosed with Barrett’s esophagus was analyzed with SNP array and exome sequencing. A custom-made panel consisting of potential germline variants was verified in the normal DNA of the affected family members. In addition, the respective tumors were analyzed for somatic loss of the wild type allele or the presence of an inactivating somatic mutation in the wild type allele. Exome sequencing revealed 244 candidate variants in the normal DNA of the proband, of which 212 variants were verified successfully. After the normal DNA of the affected family members was analyzed for the presence of the 212 potential germline variants and subsequently the respective tumors, only one potential germline variant in MSX1 (chr4: 4861985 T > G, c.359T > G, p.V120G, NM_002448) showed loss of the wild type allele in the tumor DNAs of the affected family members. A germline variant in MSX1 was identified in a Dutch family with clustering of Barrett’s esophagus and esophageal adenocarcinoma. This finding indicates that the germline defect in MSX1 may be associated with Barrett’s esophagus and cancer in this particular family

Pattern of p53 protein expression is predictive for survival in chemoradiotherapy-naive esophageal adenocarcinoma

Introduction: TP53 mutations are considered to be the driving factor in the initiation of esophageal adenocarcinoma (EAC). However, the impact of this gene and its encoded protein as a prognostic marker has not been definitely established yet. Methods: In total, 204 chemoradiotherapy (CRT)-naive patients with EAC were included for p53 protein expression evaluation by immunohistochemistry (IHC) on the resection specimens, categorized as overexpression, heterogeneous or loss of expression, and correlated with disease free survival (DFS) and overall survival (OS) using multivariable Cox regression analysis. In a subset representing all three IHC subgroups mutatio