David F. Schaeffer

Hereditary Diffuse Gastric Cancer Syndrome: CDH1 Mutations and Beyond

IMPORTANCE E-cadherin (CDH1) is a cancer predisposition gene mutated in families meeting clinically defined hereditary diffuse gastric cancer (HDGC). Reliable estimates of cancer risk and spectrum in germline mutation carriers are essential for management. For families without CDH1 mutations, genetic-based risk stratification has not been possible, resulting in limited clinical options. OBJECTIVES To derive accurate estimates of gastric and breast cancer risks in CDH1 mutation carriers and determine if germline mutations in other genes are associated with HDGC. DESIGN, SETTING, AND PARTICIPANTS Testing for CDH1 germline mutations was performed on 183 index cases meeting clinical criteria for HDGC. Penetrance was derived from 75 mutation-positive families from within this and other cohorts, comprising 3858 probands (353 with gastric cancer and 89 with breast cancer). Germline DNA from 144 HDGC probands lacking CDH1 mutations was screened using multiplexed targeted sequencing for 55 cancer-associated genes. MAIN OUTCOMES AND MEASURES Accurate estimates of gastric and breast cancer risks in CDH1 mutation carriers and the relative contribution of other cancer predisposition genes in familial gastric cancers. RESULTS Thirty-one distinct pathogenic CDH1 mutations (14 novel) were identified in 34 of 183 index cases (19%). By the age of 80 years, the cumulative incidence of gastric cancer was 70% (95% CI, 59%-80%) for males and 56% (95% CI, 44%-69%) for females, and the risk of breast cancer for females was 42% (95% CI, 23%-68%). In CDH1 mutation-negative index cases, candidate mutations were identified in 16 of 144 probands (11%), including mutations within genes of high and moderate penetrance: CTNNA1, BRCA2, STK11, SDHB, PRSS1, ATM, MSR1, and PALB2. CONCLUSIONS AND RELEVANCE This is the largest reported series of CDH1 mutation carriers, providing more precise estimates of age-associated risks of gastric and breast cancer that will improve counseling of unaffected carriers. In HDGC families lacking CDH1 mutations, testing of CTNNA1 and other tumor suppressor genes should be considered. Clinically defined HDGC families can harbor mutations in genes (ie, BRCA2) with different clinical ramifications from CDH1. Therefore, we propose that HDGC syndrome may be best defined by mutations in CDH1 and closely related genes, rather than through clinical criteria that capture families with heterogeneous susceptibility profiles.

Tumor budding in colorectal carcinoma: time to take notice

Tumor ‘budding’, loosely defined by the presence of individual cells and small clusters of tumor cells at the invasive front of carcinomas, has received much recent attention, particularly in the setting of colorectal carcinoma. It has been postulated to represent an epithelial–mesenchymal transition. Tumor budding is a well-established independent adverse prognostic factor in colorectal carcinoma that may allow for stratification of patients into risk categories more meaningful than those defined by TNM staging, and also potentially guide treatment decisions, especially in T1 and T3 N0 (Stage II, Dukes’ B) colorectal carcinoma. Unfortunately, its universal acceptance as a reportable factor has been held back by a lack of definitional uniformity with respect to both qualitative and quantitative aspects of tumor budding. The purpose of this review is fourfold: (1) to describe the morphology of tumor budding and its relationship to other potentially important features of the invasive front; (2) to summarize current knowledge regarding the prognostic significance and potential clinical implications of this histomorphological feature; (3) to highlight the challenges posed by a lack of data to allow standardization with respect to the qualitative and quantitative criteria used to define budding; and (4) to present a practical approach to the assessment of tumor budding in everyday practice.

Ductal pancreatic cancer modeling and drug screening using human pluripotent stem cell- and patient-derived tumor organoids

There are few in vitro models of exocrine pancreas development and primary human pancreatic adenocarcinoma (PDAC). We establish three-dimensional culture conditions to induce the differentiation of human pluripotent stem cells into exocrine progenitor organoids that form ductal and acinar structures in culture and in vivo. Expression of mutant KRAS or TP53 in progenitor organoids induces mutation-specific phenotypes in culture and in vivo. Expression of TP53R175H induces cytosolic SOX9 localization. In patient tumors bearing TP53 mutations, SOX9 was cytoplasmic and associated with mortality. We also define culture conditions for clonal generation of tumor organoids from freshly resected PDAC. Tumor organoids maintain the differentiation status, histoarchitecture and phenotypic heterogeneity of the primary tumor and retain patient-specific physiological changes, including hypoxia, oxygen consumption, epigenetic marks and differences in sensitivity to inhibition of the histone methyltransferase EZH2. Thus, pancreatic progenitor organoids and tumor organoids can be used to model PDAC and for drug screening to identify precision therapy strategies.

Insulin-like growth factor 2 mRNA binding protein 3 (IGF2BP3) overexpression in pancreatic ductal adenocarcinoma correlates with poor survival

BackgroundPancreatic ductal adenocarcinoma is a lethal disease with a 5-year survival rate of 4% and typically presents in an advanced stage. In this setting, prognostic markers identifying the more agrressive tumors could aid in managment decisions. Insulin-like growth factor 2 mRNA binding protein 3 (IGF2BP3, also known as IMP3 or KOC) is an oncofetal RNA-binding protein that regulates targets such as insulin-like growth factor-2 (IGF-2) and ACTB (beta-actin).MethodsWe evaluated the expression of IGF2BP3 by immunohistochemistry using a tissue microarray of 127 pancreatic ductal adenocarcinomas with tumor grade 1, 2 and 3 according to WHO criteria, and the prognostic value of IGF2BP3 expression.ResultsIGF2BP3 was found to be selectively overexpressed in pancreatic ductal adenocarcinoma tissues but not in benign pancreatic tissues. Nine (38%) patient samples of tumor grade 1 (n = 24) and 27 (44%) of tumor grade 2 (n = 61) showed expression of IGF2BP3. The highest rate of expression was seen in poorly differentiated specimen (grade 3, n = 42) with 26 (62%) positive samples. Overall survival was found to be significantly shorter in patients with IGF2BP3 expressing tumors (P = 0.024; RR 2.3, 95% CI 1.2-4.8).ConclusionsOur data suggest that IGF2BP3 overexpression identifies a subset of pancreatic ductal adenocarcinomas with an extremely poor outcome and supports the rationale for developing therapies to target the IGF pathway in this cancer.

Expression of insulin-like growth factor 2 in mesenchymal neoplasms

The insulin-like growth factor (IGF) system plays an important role in the growth and development of cells and has been implicated in oncogenesis and tumor progression. Gene expression profiling studies on limited numbers of specimens have shown high expression of IGF2, encoding the activating ligand for this system, in gastrointestinal stromal tumors (GISTs) and in synovial sarcomas. This data may have concrete clinical implications, as several reports exist of patients with GISTs suffering from severe hypoglycemia, a predicted effect of IGF2. Furthermore, new drugs targeting IGF signaling are entering clinical trials. The purpose of this study is to survey IGF2 expression at the protein level on a broad number of mesenchymal tumors representing all major diagnostic classes. By immunostaining tissue microarrays, results were obtained for 51 diagnostic categories of bone and soft-tissue tumors representing 1288 cases. Distinct membranous and/or cytoplasmic IGF2 immunoreactivity was assessed according to published criteria. Solitary fibrous tumors had the highest expression. Of 20 tumor types represented by more than 10 cases, synovial sarcomas, myxoid liposarcomas, GISTs, malignant peripheral nerve sheath tumors, chondrosarcomas, undifferentiated pleomorphic sarcomas (MFH), Ewings sarcomas and tenosynovial giant cell tumors showed high levels of expression in more than 20% of cases. Of the 445 GIST cases with clinical information, those with high expression of IGF2 had a significantly worse outcome than those with low or no expression. IGF2 protein expression among mesenchymal tumors is largely consistent with gene expression studies and suggests a potential for molecular therapy targeting the IGF signaling pathway system in these neoplasms.

Choledochal cysts: analysis of disease pattern and optimal treatment in adult and paediatric patients

BACKGROUND Choledochal cysts are dilations of the biliary tree. Although commonly reported in Asian populations, the incidence outside of Asia is as low as 1:150 000. The largest series of patients with choledochal cyst disease outside of Asia is this one, studying 70 patients treated in Vancouver between 1971 and 2003. PATIENTS AND METHODS This was a retrospective chart review. RESULTS In all, 19 paediatric and 51 adult patients were evaluated; 21% of paediatric and 25% of adult patients were Asian. All paediatric patients had type I or IV cysts, whereas adult patients represented the different subtypes. Abdominal pain was the presenting symptom in 79% of children and 88% of adults, vomiting was present in 42% of children and 63% of adults and jaundice was seen in 31.5% of children and 39% of adults. Ultrasound was used in 94.7% of children, and ERCP in 80% of adults. In all, 84% of paediatric patients, 100% of adult patients with type I cysts and 85.7% of adult patients with type IV cysts received complete cyst excision and Roux-en-Y hepaticojejunostomy. Complications in both groups were low. CONCLUSIONS Although Vancouver does have a large Asian population, this does not explain how common choledochal cysts are in this city. Although some authors argue that paediatric and adult disease are caused by different aetiologies, presentation patterns in our study between the two groups were very similar. We recommend complete cyst excision and Roux-en-Y hepaticojejunostomy as the surgery of choice, and advocate early surgery after diagnosis to promote ease of surgery and prevention of future complications.

Colorectal glandular-neuroendocrine mixed tumor: pathologic spectrum and clinical implications.

Colorectal glandular-neuroendocrine mixed tumor is an uncommon entity with ill-defined clinicopathologic characteristics. We describe the clinicopathology of 23 new cases and review 67 previously reported cases. Clinically, patients (mean age, 61.9 y; male: female, 1.0:1.1) presented with a positive fecal occult blood test or visible rectal bleeding (44%), abdominal pain or change in bowel movement pattern (25%), bowel obstruction (19%), or weight loss (19%). Endoscopically, the tumors presented as a polypoid lesion (57%), a mass lesion (30%), or an ulcerating lesion (9%). Tumors were located in the right colon (56%), transverse colon (3%), and left colon (41%). Surgical resection was the treatment of choice in 83% of cases. After follow-up for an average of 20 months, the tumor-related death rate was 68%. Histologically, 42% were classified as composite tumors and 58% were classified as collision tumors. An adenoma to carcinoma, and then carcinoma to mixed tumor progression through the APC/&bgr;-catenin pathway was seen in a majority of cases. Both the glandular and the neuroendocrine components of the mixed tumor can show a spectrum of differentiation, and each component can metastasize separately regardless of its percentage volume. On the basis of the combined analysis of the pathologic spectrum and the clinical behavior of our series and previously reported cases, we propose a new classification system that reflects the differentiation of each component in colorectal glandular-neuroendocrine mixed tumor to facilitate uniform reporting and to better predict its clinical behavior.

Multidisciplinary management of ruptured hepatocellular carcinoma

Spontaneous rupture of hepatocellular carcinoma (HCC) is a dramatic presentation of the disease. Most published studies are from Asian centers, and North American experience is limited. This study was under-taken to review the experience of ruptured HCC at a North American multidisciplinary unit. Thirty pa-tients presenting with ruptured HCC at a tertiary care center from 1985 to 2004 were studied retrospectively and analyzed according to the demographics, clinical presentation, tumor characteristics, treatment, and outcome in four treatment groups: emergency resection, delayed resection (resection after angiographic embolization), transcatheter arterial embolization (TAE), and conservative management. Ten, 10, 7, and 3 patients underwent emergency resection, delayed resection, TAE, and conservative treat-ment, respectively. The mean age of all patients was 57 years, and the mean Child-Turcotte-Pugh score was 7 ± 2. Cirrhosis was present in 57% of the patients. Seventy percent of tumors were greater than 5 cm in diameter, and 68% of patients had multiple tumors. There was a trend toward higher 30-day mortality in the emergency resection group than in the delayed resection group. One-year survival was significantly bet-ter in the delayed resection group. In selected patients, the multidisciplinary approach of angiographic em-bolization and delayed resection affords better short-term survival than emergency resection.

Prognostic role and implications of mutation status of tumor suppressor gene ARID1A in cancer: a systematic review and meta-analysis

Loss of the tumor suppressor gene AT-rich interactive domain-containing protein 1A (ARID1A) has been demonstrated in several cancers, but its prognostic role is unknown. We aimed to investigate the risk associated with loss of ARID1A (ARID1A−) for all-cause mortality, cancer-specific mortality and recurrence of disease in subjects with cancer. PubMed and SCOPUS search from database inception until 01/31/2015 without language restriction was conducted, contacting authors for unpublished data. Eligible were prospective studies reporting data on prognostic parameters in subjects with cancer, comparing participants with presence of ARID1A (ARID1A+) vs. ARID1A−, assessed either via immunohistochemistry (loss of expression) or with genetic testing (presence of mutation). Data were summarized using risk ratios (RR) for number of deaths/recurrences and hazard ratios (HR) for time-dependent risk related to ARID1A− adjusted for potential confounders. Of 136 hits, 25 studies with 5,651 participants (28 cohorts; ARID1A−: n = 1,701; ARID1A+: n = 3,950), with a mean follow-up period of 4.7 ± 1.8 years, were meta-analyzed. Compared to ARID1A+, ARID1A− significantly increased cancer-specific mortality (studies = 3; RR = 1.55, 95% confidence interval (CI) = 1.19–2.00, I2 = 31%). Using HRs adjusted for potential confounders, ARID1A− was associated with a greater risk of cancer-specific mortality (studies = 2; HR = 2.55, 95%CI = 1.19–5.45, I2 = 19%) and cancer recurrence (studies = 10; HR = 1.93, 95%CI = 1.22–3.05, I2 = 76%). On the basis of these results, we have demonstrated that loss of ARID1A shortened time to cancer-specific mortality, and to recurrence of cancer when adjusting for potential confounders. For its role, this gene should be considered as an important potential target for personalized medicine in cancer treatment.

Bone morphogenetic protein antagonist gremlin-1 regulates colon cancer progression.

Abstract Bone morphogenetic proteins (BMP) are phylogenetically conserved signaling molecules of the transforming growth factor-beta (TGF-beta) superfamily of proteins, involved in developmental and (patho)physiological processes, including cancer. BMP signaling has been regarded as tumor-suppressive in colorectal cancer (CRC) by reducing cancer cell proliferation and invasion, and by impairing epithelial-to-mesenchymal transition (EMT). Here, we mined existing proteomic repositories to explore the expression of BMPs in CRC. We found that the BMP antagonist gremlin-1 (GREM1) is secreted from heterotypic tumor-host cell interactions. We then sought to investigate whether GREM1 is contextually and mechanistically associated with EMT in CRC. Using immunohistochemistry, we showed that GREM1-expressing stromal cells harbor prominent features of myofibroblasts (i.e., cancer-associated fibroblasts), such as expression of α-smooth muscle actin and laminin-beta-1, and were in contextual proximity to invasion fronts with loss of the tight junction protein occludin and parallel nuclear accumulation of β-catenin, two prominent EMT hallmarks. Furthermore, in vitro assays demonstrated that GREM1-dependent suppression of BMP signaling results in EMT induction, characterized by cadherin switching (loss of E-cadherin-upregulation of N-cadherin) and overexpression of Snail. Collectively, our data support that GREM1 promotes the loss of cancer cell differentiation at the cancer invasion front, a mechanism that may facilitate tumor progression.