ST6GAL1 sialyltransferase promotes acinar to ductal metaplasia and pancreatic cancer progression.

The role of aberrant glycosylation in pancreatic ductal adenocarcinoma (PDAC) remains an under-investigated area of research. In this study, we determined that ST6 ß-galactoside α2,6 sialyltransferase 1 (ST6GAL1), which adds α2,6-linked sialic acids to N-glycosylated proteins, was upregulated in patients with early-stage PDAC and was further increased in advanced disease. A tumor-promoting function for ST6GAL1 was elucidated using tumor xenograft experiments with human PDAC cells. Additionally, we developed a genetically engineered mouse (GEM) model with transgenic expression of ST6GAL1 in the pancreas and found that mice with dual expression of ST6GAL1 and oncogenic KRASG12D had greatly accelerated PDAC progression compared with mice expressing KRASG12D alone. As ST6GAL1 imparts progenitor-like characteristics, we interrogated ST6GAL1's role in acinar to ductal metaplasia (ADM), a process that fosters neoplasia by reprogramming acinar cells into ductal, progenitor-like cells. We verified ST6GAL1 promotes ADM using multiple models including the 266-6 cell line, GEM-derived organoids and tissues, and an in vivo model of inflammation-induced ADM. EGFR is a key driver of ADM and is known to be activated by ST6GAL1-mediated sialylation. Importantly, EGFR activation was dramatically increased in acinar cells and organoids from mice with transgenic ST6GAL1 expression. These collective results highlight a glycosylation-dependent mechanism involved in early stages of pancreatic neoplasia.

Evaluation of lymph node numbers for adequate staging of Stage II and III colon cancer.

BACKGROUND: Although evaluation of at least 12 lymph nodes (LNs) is recommended as the minimum number of nodes required for accurate staging of colon cancer patients, there is disagreement on what constitutes an adequate identification of such LNs. METHODS: To evaluate the minimum number of LNs for adequate staging of Stage II and III colon cancer, 490 patients were categorized into groups based on 1-6, 7-11, 12-19, and ≥ 20 LNs collected. RESULTS: For patients with Stage II or III disease, examination of 12 LNs was not significantly associated with recurrence or mortality. For Stage II (HR = 0.33; 95% CI, 0.12-0.91), but not for Stage III patients (HR = 1.59; 95% CI, 0.54-4.64), examination of ≥20 LNs was associated with a reduced risk of recurrence within 2 years. However, examination of ≥20 LNs had a 55% (Stage II, HR = 0.45; 95% CI, 0.23-0.87) and a 31% (Stage III, HR = 0.69; 95% CI, 0.38-1.26) decreased risk of mortality, respectively. For each six additional LNs examined from Stage III patients, there was a 19% increased probability of finding a positive LN (parameter estimate = 0.18510, p < 0.0001). For Stage II and III colon cancers, there was improved survival and a decreased risk of recurrence with an increased number of LNs examined, regardless of the cutoff-points. Examination of ≥7 or ≥12 LNs had similar outcomes, but there were significant outcome benefits at the ≥20 cutoff-point only for Stage II patients. For Stage III patients, examination of 6 additional LNs detected one additional positive LN. CONCLUSIONS: Thus, the 12 LN cut-off point cannot be supported as requisite in determining adequate staging of colon cancer based on current data. However, a minimum of 6 LNs should be examined for adequate staging of Stage II and III colon cancer patients.

Merkel cell carcinoma: correlation of KIT expression with survival and evaluation of KIT gene mutational status.

Merkel cell carcinoma is one of the most aggressive primary cutaneous malignancies. Because some Merkel cell carcinomas express the receptor tyrosine kinase KIT, we aimed to evaluate the correlation of KIT expression with the outcome and the presence of activating mutations in the KIT gene in Merkel cell carcinoma. A total of 49 tumors from 40 patients with a diagnosis of Merkel cell carcinoma were identified, of which 30 cases from 21 patients were used in the study. KIT expression was assessed by immunohistochemistry on formalin-fixed, paraffin-embedded material. Cases were divided into low expressors (0-1+ staining intensity) and high expressors (2-3+ staining intensity). Direct sequencing of exons 9, 11, 13, 17, and 18 of the KIT gene spanning the extracellular, juxtamembrane, and tyrosine kinase domains was performed for cases with high KIT expression. Thirty tumors from 21 patients were analyzed for KIT expression. High KIT expression was seen in 67% of the patients. Five-year survival rates in tumors expressing high versus low levels of KIT were 0% versus 57.8%, respectively; however, this dramatic difference did not reach statistical significance (P = .07). A total of 4 point mutations were identified in 18 tumors analyzed. Two of these were silent mutations involving exons 17 and 18, and 2 involved intron 16-17. Two of the identified mutations may represent novel polymorphisms. Our work suggests a correlation between KIT expression and a worse prognosis in Merkel cell carcinoma patients, raising the possibility of an active role of this receptor in tumor progression and metastasis. However, we did not identify KIT activating mutations in any of the tumors analyzed.

Dynamic telecytopathology of on site rapid cytology diagnoses for pancreatic carcinoma.

BACKGROUND: Diagnosis of pancreatic lesions can be accurately performed by endoscopic ultrasound guided fine needle aspiration (EUS-FNA) with onsite cytopathologists to assess specimen adequacy and to determine a preliminary diagnosis. Considerable time is needed to perform on-site assessments. This takes away work time of cytopathologists and prohibits them from serving remote locations. It is therefore logical to ask if real-time telecytopathology could be used to assess specimen adequacy and if telecytopathology diagnosis has the same level of agreement to the final diagnosis as that of onsite evaluation. In this study, we compare agreement between cytodiagnoses rendered using telecytopathology with onsite and final interpretations. METHOD: 40 Diff-Quik-stained EUS-FNA were re-evaluated retrospectively (patient ages 31-62, 19:21 male:female, 15 non-malignant lesions, 25 malignant lesions as classified by final diagnosis). Each previously assessed by a cytopathologist and finally reviewed by the same or different cytopathologist. Blinded to the final diagnosis, a resident pathologist re-screened all slides for each case, selected a slide and marked the diagnostic cells most representative of the lesion. Blinded to the diagnosis, one cytopathologist assessed the marked cells through a real time remotely operated telecytopathology system (MedMicroscopy). Diagnosis and time spent were recorded. Kappa statistic was used to compare agreements between telecytopathology vs. original onsite vs. final diagnoses. RESULTS: Time spent for prescreening ranged from 1 to 5 minutes (mean 2.6 +/- 1.3 minutes) and time spent for telecytopathology diagnosis ranged from 2-20 minutes (mean 7.5 +/- 4.5 minutes). Kappa statistics, K, was as follows: telecytopathology versus onsite diagnosis K, 95% CI = 0.65, 0.41-0.88, for telecytopathology versus final K, 95% CI = 0.61, 0.37-0.85 and for onsite diagnosis versus final K, 95% CI = 0.79, 0.61-0.98. There is no significant difference in agreement between onsite and telecytopathology diagnoses. Kappa values for telecytopathology were less than onsite evaluation when compared to the final diagnosis; however, the difference was not statistically significant. CONCLUSION: This retrospective study demonstrates the potential use of telecytopathology as a valid substitute for onsite evaluation of pancreatic carcinoma by EUS-FNA.

Endoscopic ultrasound-guided fine needle aspiration biopsy of suspected cholangiocarcinoma.

BACKGROUND AND AIMS: Despite advances in endoscopic techniques for sampling bile duct strictures, the diagnosis of cholangiocarcinoma remains a challenge. The purpose of this study was to evaluate the yield of EUS-FNA and its impact on patient management for patients with suspected cholangiocarcinoma. METHODS: All patients undergoing EUS for the evaluation of suspected malignant biliary strictures were prospectively evaluated over a 23-month period. A single gastroenterologist performed all EUS-FNAs in the presence of a cytopathologist. Reference standard for final diagnosis included surgery, death from disease, and clinical and/or imaging follow-up. RESULTS: Twenty-eight patients (mean age 67 years [SD +/- 11], 72% male) were evaluated. Most patients (91%) presented with obstructive jaundice, and all except 1 had nondiagnostic sampling of the biliary lesions either at ERCP (88%), percutaneous transhepatic cholangiogram (n = 2), and/or computed tomography-guided biopsy (n = 1). Sixty-seven percent (14/21) had no definitive mass seen on prior abdominal imaging studies. The mean tumor size by EUS was 19 mm x 16 mm with a median number of passes to diagnosis of 3 (range 1-7). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 86%, 100%, 100%, 57%, and 88%, respectively. EUS-FNA had a positive impact on patient management in 84% of patients: preventing surgery for tissue diagnosis in patients with inoperable disease (n = 10), facilitating surgery in patients with unidentifiable cancer by other modalities (n = 8), and avoiding surgery in benign disease (n = 4). CONCLUSIONS: Given the apparent accuracy and safety of EUS with FNA for imaging bile duct mass lesions and for obtaining a tissue diagnosis in patients with suspected cholangiocarcinoma, this technology may represent a new approach to diagnosis especially when other methods fail. The ability to obtain a definite diagnosis has a significant impact on patient management.

Expression of p53 and proliferation index as prognostic factors in gastrointestinal sarcomas.

BACKGROUND: Sarcomas arising in the gastrointestinal (GI) tract are rare tumors. Molecular markers could be associated with prognosis in these types of tumors. METHODS: We performed a retrospective analysis of adult patients with sarcomas arising in the GI tract at the National Institute of Medical Sciences in Mexico City and the University of Alabama at Birmingham Hospital. All histological types were included. Patient, tumor, and treatment factors were analyzed, with overall survival as the main outcome variable. Expression of p53 and cellular proliferation antigen Ki-67 was also analyzed. Statistical analysis was performed by log-rank test and Cox regression. Significance was defined as P <.05. RESULTS: Forty-seven patients were analyzed. The median patient age was 53 years (range, 16-82 years). Twenty-five patients (53%) were women. The stomach was the most common site of presentation. The mean tumor size was 14 cm (2-45 cm). A complete resection was achieved in 40 patients. With a median follow-up of 30 months, the actuarial 3-year survival was 68%. Univariate analysis identified overexpression of p53 and Ki-67, high tumor grade, tumor size >10 cm, and incomplete resection as significant negative prognostic factors. Hispanic race and good performance status were significantly associated with prolonged survival. On multivariate analysis, overexpression of p53 was the only independent negative prognostic factor. CONCLUSIONS: Overexpression of p53 is the strongest predictor of poor prognosis in patients with sarcomas of the GI tract.