68Ga-DOTATATE PET/CT imaging of indeterminate pulmonary nodules and lung cancer

PURPOSE

18F-FDG PET/CT is widely used to evaluate indeterminate pulmonary nodules (IPNs). False positive results occur, especially from active granulomatous nodules. A PET-based imaging agent with superior specificity to 18F-FDG for IPNs, is badly needed, especially in areas of endemic granulomatous nodules. Somatostatin receptors (SSTR) are expressed in many malignant cells including small cell and non-small cell lung cancers (NSCLCs). 68Ga-DOTATATE, a positron emitter labeled somatostatin analog, combined with PET/CT imaging, may improve the diagnosis of IPNs over 18F-FDG by reducing false positives. Our study purpose was to test this hypothesis in our region with high endemic granulomatous IPNs.

METHODS

We prospectively performed 68Ga-DOTATATE PET/CT and 18F-FDG PET/CT scans in the same 30 patients with newly diagnosed, treatment-naïve lung cancer (N = 14) or IPNs (N = 15) and one metastatic nodule. 68Ga-DOTATATE SUVmax levels at or above 1.5 were considered likely malignant. We analyzed the scan results, correlating with ultimate diagnosis via biopsy or 2-year chest CT follow-up. We also correlated 68Ga-DOTATATE uptake with immunohistochemical (IHC) staining for SSTR subtype 2A (SSTR2A) in pathological specimens.

RESULTS

We analyzed 31 lesions in 30 individuals, with 14 (45%) being non-neuroendocrine lung cancers and 1 (3%) being metastatic disease. McNemar's result comparing the two radiopharmaceuticals (p = 0.65) indicates that their accuracy of diagnosis in this indication are equivalent. 68Ga-DOTATATE was more specific (94% compared to 81%) and less sensitive 73% compared to 93%) than 18F-FDG. 68Ga-DOTATATE uptake correlated with SSTR2A expression in tumor stroma determined by immunohistochemical (IHC) staining in 5 of 9 (55%) NSCLCs.

CONCLUSION

68Ga-DOTATATE and 18F-FDG PET/CT had equivalent accuracy in the diagnosis of non-neuroendocrine lung cancer and 68Ga-DOTATATE was more specific than 18F-FDG for the diagnosis of IPNs. IHC staining for SSTR2A receptor expression correlated with tumor stroma but not tumor cells.

Abstract A16: Smad4 pathways modulate induction of the chemokine Ccl20 and repress inflammation-induced carcinogenesis in mouse colon

Inflammation regulates many aspects of gut homeostasis but is also a key component of colon cancer progression. While TGFβ signaling is known to regulate inflammatory responses within immune cells, we have uncovered a novel regulatory pathway in which TGFβ and BMP signaling suppress responses to inflammatory stimuli within the colonic epithelium. Using mice with conditional deletion of Smad4 in intestinal epithelium, we found that CCL20 expression was increased with Smad4 loss. Similarly, in murine immortalized colonocytes and human colon cancer cell lines, blocking TGFβ and/or BMP receptors increased CCL20 expression. CCL20 is upregulated in response to inflammatory signals such as TNF and IL-1β. CCL20 is also upregulated in colon cancer but the mechanism is not understood. We found that pre-treatment of colonocytes or colon cancer cells with TGFβ1 and BMP2 completely suppressed TNF- or IL-1β-induced CCL20 expression at the level of gene transcription. By chromatin immunoprecipitation, we found that TGFβ1/BMP2 treatment impaired binding of NFκB and phospho-STAT3 to the CCL20 promoter. To understand the significance of this regulation in chronic inflammation, we subjected Smad4 deleted and control mice to three rounds of dextran sodium sulfate (DSS)-mediated damage to the distal colon. We found that loss of Smad4 in mouse colonic epithelium was sufficient to induce tumorigenesis following damage-induced inflammation. Following DSS-mediated damage, Smad4-null epithelium developed invasive colorectal adenocarcinoma within two months of DSS treatment while Smad4+ control mice never develop tumors following DSS exposure. The Smad4 null tumors were histologically similar to those of human colitis-associated colon cancers. Prior to tumor formation, we saw an increase in CD8+ cells in Smad4-deleted colons, suggesting that tumor progression involves bidirectional crosstalk between the epithelium and immune cells and that this crosstalk is regulated in part by Smad4-mediated signaling within the epithelium. SMAD4, TGFβ receptors, or BMP receptors are often mutated in colon cancer. This loss of TGFβ and/or BMP signaling likely facilitates epithelial-immune cell crosstalk in colitis-associated colon cancers.

Citation Format: Anna L. Means, Tanner J. Freeman, Connie J. Weaver, Chanjuan Shi, Mary K. Washington, Bronson C. Wessinger, Tasia Brown, David K. Flaherty, Kevin P. Weller, Robert J. Coffey, Keith T. Wilson, Robert D. Beauchamp. Smad4 pathways modulate induction of the chemokine Ccl20 and repress inflammation-induced carcinogenesis in mouse colon. [abstract]. In: Proceedings of the AACR Special Conference on Colorectal Cancer: From Initiation to Outcomes; 2016 Sep 17-20; Tampa, FL. Philadelphia (PA): AACR; Cancer Res 2017;77(3 Suppl):Abstract nr A16.

Micropapillary colorectal carcinoma: clinical, pathological and molecular properties, including evidence of epithelial-mesenchymal transition

AIMS

Colorectal carcinoma (CRC) with micropapillary (MP) features has only been described recently and is still being characterized.

METHODS AND RESULTS

We reviewed the clinicopathological and molecular features of 42 CRC with MP features. Twenty-nine cases were also evaluated for immunohistochemical evidence of epithelial-mesenchymal transition (EMT). The extent of MP features within our cohort ranged from 5% (13 cases) to 100% (one case). Twenty-seven cases featured prominent cribriforming with dirty necrosis in the non-MP component; nine displayed mucinous features. Twenty-four of 29 cases (83%) demonstrated evidence of EMT. Thirty-six cases (86%) showed advanced T-category (pT3 or pT4), 31 (74%) had lymph node metastases and 23 (55%) had distant metastases. Median overall follow-up was 36 months. Seventeen patients (40%) died of disease, with median survival of 23 months. Mutations were seen in 17 of 31 tested cases (55%), including 11 KRAS mutations and four BRAF V600E mutations. Microsatellite instability testing was performed on 21 cases; all were microsatellite-stable. Compared to a cohort of 972 conventional CRC, MP CRC was more likely to present as stage IV disease (P < 0.001), but patients with MP CRC showed no significant differences in overall survival after adjusting for stage.

CONCLUSIONS

Micropapillary features in CRC portend a high likelihood of advanced local disease and distant metastases. MP CRC is often associated with a cribriform pattern elsewhere in the tumour and cystic nodal metastases with prominent necrosis. They also show frequent mutations in KRAS and BRAF. Immunohistochemical evidence of EMT is common in MP CRC.

PD-1 inhibitor gastroenterocolitis: case series and appraisal of 'immunomodulatory gastroenterocolitis'

AIMS

PD-1 inhibitors facilitate immune response against certain tumour types, including melanoma. These drugs have led to prolonged survival but can also result in autoimmune-type side effects, including gastrointestinal inflammation. The histopathological effects of this medication class have not been well studied.

METHODS AND RESULTS

We identified 37 gastrointestinal tract biopsies from 20 patients taking a PD-1 or PD-L1 inhibitor and evaluated clinicopathological findings. Diarrhoea was the most common symptom, and endoscopic findings ranged from mild erythema to erosion/ulceration. Common histological findings included lamina propria expansion, villous blunting (if applicable), intra-epithelial neutrophils and increased crypt/gland apoptosis, although intra-epithelial lymphocytes were rarely prominent. A few cases showed crypt rupture with resultant histiocytic/granulomatous response. Most patients responded to drug cessation and/or steroids, but follow-up endoscopies were not performed.

CONCLUSIONS

PD-1/PD-L1 inhibitors can cause gastritis, enteritis and colitis, similar to other immunomodulatory antibodies (such as CTLA-4 inhibitors and PI3Kδ inhibitors), but the histological findings vary somewhat among drug classes. Clinical history, lack of prominent intra-epithelial lymphocytes and crypt rupture may help to distinguish PD-1 inhibitor gastroenterocolitis from mimics, which include other medication effect, inflammatory bowel disease, graft-versus-host disease, cytomegalovirus infection and autoimmune enteropathy.

Abstract B71: Resistance to MEK inhibition in pancreatic cancer is associated with amphiregulin mediated EGFR-STAT3 activation

Introduction: Mutations in the KRAS oncogene occur in the majority of pancreatic ductal adenocarcinomas (PDAC), resulting in aberrant activation of the MAPK (RAS-RAF-MEK-ERK) pathway, driving malignant progression. Targeting KRAS has remained an elusive goal. Therefore, efforts have focused on targeting downstream effectors of RAS. The clinical efficacy of MEK inhibitors in other malignancies confirms that targeting the MAPK pathway has therapeutic potential. Unfortunately, clinical trials of MAPK-directed therapies have been unsuccessful in PDAC. Here, we report a novel mechanism of resistance to MAPK-directed therapies, which is associated with amphiregulin (AREG)-mediated activation of EGFR-STAT3 signaling.

Experimental procedure: The effects of MEK inhibition on the phosphorylation of multiple signaling proteins and EGF family ligands was assessed. Activation of MAPK and STAT3 was quantified in human pancreatic tissues, and then correlated with overall survival (OS). Cell lysates from mouse PanIN lines derived from the LSL-KrasG12D/+;Pdx1Cre/+ and PDA line from LSL-KrasG12D/+; Trp53R172H/+;Pdx1Cre/+ mouse models of PDAC were immunoblotted for activated MAPK and STAT3 expression. AREG release was measured in the conditioned media of PDAC cells treated with MEK, EGFR, STAT3, and/or TACE inhibitors and TACE siRNA knock down cells treated with MEK, EGFR, or STAT3 inhibitors. Cell invasion, colony formation, spheroid formation, metabolic activity, cell cycle analysis, and apoptosis assays were performed with human PDAC cells treated with inhibitors for TACE, MEK, EGFR and STAT3 in combinations. PDAC xenografts and patient derived xenografts (PDXs) were treated either with vehicle, the MEK inhibitor AZD6244, the STAT3 inhibitor AZD1480 or both drugs and analyzed for spheroid growth. PKT mice (Ptf1acre/+;LSL-KrasG12D;Tgfbr2fl/fl) were treated with AZD6244 and AZD1480 and assessed for OS. Tissues from the xenografts and PKT mice were analyzed for cell proliferation and apoptosis markers. Plasma from the PKT mice treated with the drugs and their combinations was analyzed released AREG by ELISA.

Results: Targeting the MAPK pathway is a novel approach to inhibit KRAS mutant tumor progression and improve therapeutic response in PDAC. However, our results show that MAPK inhibition leads to activation of TACE and EGFR and subsequent activation of STAT3 signaling. Combined inhibition of MEK/STAT3 or MEK/EGFR resulted in sustained blockade of MEK, EGFR and STAT3 signaling, decreased cell invasion, colony formation, reduced spheroid size, and metabolic activity in vitro. Growth of flank PDAC xenografts and human PDX tumors in vivo were significantly decreased with combined MEK and STAT3 inhibition when compared to vehicle or monotherapy treatment. OS in PKT mice was extended to a median of 85 days with combined MEK and STAT3 inhibition vs. 52 days for vehicle treated mice (p &lt; 0.001). AREG release was significantly reduced with combined MEK/STAT3 inhibition. TACE siRNA in PDAC cells confirms the role of AREG release in mediating EGFR signaling and overcoming MEK inhibitor resistance. Evaluation of TACE activation and AREG shedding/release in response to MEK inhibition demonstrated that resistance to MEK inhibition in PDAC is mediated by reactivation of the STAT3 pathway, which is strongly influenced by increased AREG production.

Conclusions: Our study provides insights into the molecular mechanisms that help explain the heterogeneous response and therapeutic resistance of PDAC to MAPK pathway inhibition and provide a strong rationale that AREG mediated EGFR-STAT3 pathway activation is a major resistance mechanism that impairs the efficacy of MEK inhibitors.

Citation Format: Nagaraj Nagathihalli, Jason Castellanos, Chanjuan Shi, Casey Roberts, Michael VanSaun, Nipun Merchant.{Authors}. Resistance to MEK inhibition in pancreatic cancer is associated with amphiregulin mediated EGFR-STAT3 activation. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2016 May 12-15; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(24 Suppl):Abstract nr B71.

Abstract B78: RAD51 sensitizes pancreatic cancer cells to AKT inhibition

Introduction: Cell survival after DNA damage relies on DNA repair processes to protect the integrity of the genome. The repair process involves DNA homologous recombination system that requires numerous factors including the recombinase RAD51 and BRCA2, which co-localize to replication centers within the damaged cell nucleus. The defective DNA repair mechanisms in cancer cells can be exploited for therapy, when abrogated DNA double-strand breaks (DSB) repair causes genomic instability and increase in cancer cell sensitivity to consequential cellular apoptosis. Targeted therapies are challenged by emergence of tumor cell resistance associated with downstream components of KRAS signaling pathways in pancreatic ductal adenocarcinoma (PDAC). It is, therefore, essential to develop novel therapeutic strategies to overcome chemoresistance. The PI3K/AKT pathway is activated in human PDAC and mouse models of KRAS-driven PDAC. We sought to determine the effects of RAD51 on therapeutic sensitivity and resistance to AKT inhibition.

Experimental procedure: RAD51 expression was determined in human pancreatic tissues from a tissue microarray (TMA) and analyzed for overall survival (OS). Cell lysates from mouse cell lines derived from the LSL-KrasG12D/+;Pdx1Cre/+ (PanIN) and LSL-KrasG12D/+; Trp53R172H/+;Pdx1Cre/+ (PDA and LMP) genetic mouse models of PDAC were immunoblotted for RAD51 expression. IC50 values of B02 (a RAD51 inhibitor) treatment in human PDAC cell lines were determined. Orthotopic tumors were generated with direct injections of luciferase-tagged PANC1 cells and were treated with B02. Bioluminescence imaging (BLI) was utilized to monitor orthotopic tumor growth and treatment response. Colony formation, spheroid generation size and metabolic activity, cell cycle analysis and apoptosis assays were performed in human PDAC cells treated with inhibitors for RAD51 (B02) and/or AKT (MK2206). PDA (express low RAD51) and LMP (express high RAD51) cell lines from mice were treated with B02 and/or MK2206 and analyzed for their colony forming ability. The in vitro sensitivities of BRCA2 deficient Capan1 and BRCA2 proficient MiaPaCa2 cell lines to MK2206 were compared by analyzing cell proliferation and colony formation. RAD51 knockdown cells were treated with MK2206 and analyzed for cell proliferation and apoptosis using flow cytometry.

Results: RAD51 expression confirmed a stepwise increase from normal pancreas to chronic pancreatitis through advancing grade and stage of PDAC. Patients with PDAC tumors expressing high levels of RAD51 had significantly higher tumor grade, stage, and lower OS when compared with patients with tumors that had low RAD51 expression (median survival of 15 months vs 37 months, respectively; P=0.025). BRCA2 deficient Capan1 PDAC cells were sensitive to MK2206 when compared to BRCA2 proficient MiaPaCa2 cells. Bioluminescent imaging (BLI) guided tumor growth analysis confirmed that RAD51 inhibition with B02 treatment decreased tumor growth in PDAC cells. B02 and MK2206 treated PDA and LMP cells showed synergistic downregulation of colony formation in comparison to either B02 or MK2206 drugs treated cells. RAD51 knockdown cells treated with MK2206 showed enhanced cell apoptosis and attenuated cell proliferation.

Conclusions: Our findings indicate that RAD51 inhibition increases sensitivity to AKT inhibition. RAD51 expression levels in PDAC tumors may be useful in identification of PDAC patients who will benefit from this therapy.

Citation Format: Surpiya Srinivasan, Chanjuan Shi, Casey Roberts, Xizi Dai, Fanuel Messaggio, Krisztina Kovacs, Michael VanSaun, Nipun Merchant, Nagaraj Nagathihalli.{Authors}. RAD51 sensitizes pancreatic cancer cells to AKT inhibition. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2016 May 12-15; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(24 Suppl):Abstract nr B78.

Abstract B19: Kras mutation imparts neoplastic potential on duct cells but not acinar cells in a mouse model of obstructive chronic pancreatitis

Understanding the progression of human pancreatic cancer is difficult due to the late stage of diagnosis of this deadly disease. We must therefore rely upon robust model systems to understand how pancreatic cancer arises, how its acute and chronic phases of progression are regulated, and how best to identify and treat it, hopefully still in the early stage. Models of pancreatic ductal adenocarcinoma (PDAC) that accurately reflect human disease are still being developed. To mimic human disease, PDAC must arise from mutations occurring in adult animals and with etiologies relevant to humans. We developed a new mouse model that incorporates obstructive chronic pancreatitis with tissue-specific, adult-onset expression of mutant Kras. We found that KrasG12D expression in duct cells but not in acinar cells led to progression of metaplastic ducts to eventual dysplasia and cancer. In early-stage disease, Kras mutation in acinar cells led to increased acinar-to-ductal metaplasia but did not downregulate p53, thus leading to reduced cell survival. Ducts naturally express much lower p53 levels, however, and there was increased survival of KrasG12D-mediated, duct-derived metaplastic cells. Furthermore, acinar cells upregulated Pdx1 during acinar-to-ductal metaplasia while duct cells did not do so during their metaplastic transition. Without chronic pancreatitis, Kras mutation in acinar cells causes abundant Pancreatic Intraepithelial Neoplasm (PanIN)-like lesions. However, overexpression of Pdx1 in acinar cells in this context permitted acinar-to-ductal metaplasia but prevented PanIN-like lesion formation, suggesting that Pdx1 can repress neoplastic progression. In summary, in the setting of obstructive chronic pancreatitis, ducts are the principal source of cancer development via reduced Pdx1 and p53 levels and increased cell survival.

Citation Format: Fong C. Pan, Jessica N. Kim, Chanjuan Shi, Mary K. Washington, Maike Sander, Maureen Gannon, Robert D. Beauchamp, Christopher V. Wright, Anna L. Means.{Authors}. Kras mutation imparts neoplastic potential on duct cells but not acinar cells in a mouse model of obstructive chronic pancreatitis. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2016 May 12-15; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(24 Suppl):Abstract nr B19.

[Surveillance on the epidemiological and etiological characteristics of hand-foot-mouth disease during the outbreaks in three cities of Jiangsu province, 2012-2015]

Objective: To analyze the epidemiological and etiological characteristics through monitoring the outbreaks of hand-foot-mouth disease (HFMD), in three cities of Jiangsu province from 2012 to 2015 and to provide evidence for prevention and control of the disease. Methods: Data related to cases of HFMD during the outbreaks was collected through active surveillance programs in three cities of Jiangsu province, under the guidelines of clusters and outbreaks of HFMD (2012 edition HFMD). Features related to clusters and outbreaks of the disease were identified according to the real-time RT-PCR detection. Descriptive analysis was conducted to understand the type/subtype of HFMD virus and time, area, place and extent of the outbreaks. Logistic regression was used to explore the influencing factors. Results: From 2012 to 2015, a total of 1 425 HFMD epidemics, including 1 314 clusters and 111 outbreaks were reported. Two incidence peaks were observed each year, between March and June, as well as between September and December, accounting for 58.18% (829/1 425), 33.68% (480/1 425), respectively. Most HFMD clusters and outbreaks were reported in Wuxi city, accounting for 59.30% (845/1 425) of the total. Most HFMD clusters and outbreaks happened in kindergartens, accounting for 68.63% (978/1 425) of the total. A total of 931 HFMD clusters and outbreaks were confirmed under laboratory findings. The main pathogens were Entervirus type 71 (EV71) in 2013 and Coxsackie A16 (Cox A16) in 2015, respectively, while both EV71 and Cox A16 were predominant in 2012 and 2014. With multivariate backward conditional regression, surrounding environment was identified as important risk factor associated with the attack rate. Health condition of the environment was quite good, with low attack rates (middle vs. bad: OR=0.150, 95% CI: 0.034-0.667; good vs. bad: OR=0.072, 95%CI: 0.016-0.317). Time between the onset of index patient and the reporting of HFMD clusters or outbreaks was important in the control program of HFMD epidemics (4-7 d vs. 1-3 d: OR=3.452, 95%CI: 2.293-5.198; 8 d vs. 1-3 d: OR=12.108, 95%CI: 7.767-18.763). Conclusions: The clusters and outbreaks of HFMD happened in Jiangsu province showed an obvious feature of seasonality. The predominant types or subtypes of the virus varied in different years. Kindergartens were the hard-hit places of HFMD clusters and outbreaks. Timely report of the disease appeared the key point regarding the control of HFMD clusters and outbreaks.

Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine neoplasms include well-differentiated pancreatic neuroendocrine tumors (PanNETs) and neuroendocrine carcinomas (NECs) with well-differentiated PanNETs accounting for most cases. Other pancreatic primaries and metastatic carcinomas from other sites can mimic pancreatic neuroendocrine neoplasms. Immunohistochemical studies can be used to aid in the differential diagnosis. However, no specific markers are available to differentiate PanNETs from NETs of other sites. Although NECs are uniformly deadly, PanNETs have variable prognosis. Morphology alone cannot predict the tumor behavior. Although some pathologic features are associated with an aggressive course, Ki67 is the only prognostic molecular marker routinely used in clinical practice.

Inactivation of Cronobacter sakazakii in reconstituted infant formula by combination of thymoquinone and mild heat

AIMS

The objective of this study was to determine the combined effect of thymoquinone (TQ) and mild heat on Cronobacter sakazakii in reconstituted infant formula.

METHODS AND RESULTS

Reconstituted infant formula samples inoculated with a mixture of four C. sakazakii strains (approx. 6·5 log CFU ml(-1) ) were prepared with various concentrations of TQ (0, 5, 10, 20 and 30 mmol l(-1) ) and were heated to 45, 50 and 55°C for 0, 10, 20, 30, 60 and 120 min, and the surviving populations of C. sakazakii at each sampling time were enumerated. To elucidate the mode of action of TQ, membrane integrity and changes in cell morphology were examined by LIVE/DEAD(®) BacLight(™) bacterial viability kit and field emission scanning electron microscope respectively. TQ at 30 mmol l(-1) reduced the pathogen to undetectable level in between 60 and 120 min at 45°C, 60 min at 50°C and 10 min at 55°C respectively.

CONCLUSIONS

Our results demonstrated that the combined treatments significantly reduced (P < 0·05) the population of C. sakazakii, compared to the control. Cronobacter sakazakii numbers were reduced much more rapidly with higher temperatures and increased concentrations of TQ. And combined treatment inactivated pathogen partly by causing cell membrane disruption.

SIGNIFICANCE AND IMPACT OF THE STUDY

These findings suggested that TQ, together with mild heat, may have potential application in infant formula to control C. sakazakii before consumption and therefore is a possible way to prevent infections associated with C. sakazakii in infant formula.

Differences in Microsatellite Instability Profiles between Endometrioid and Colorectal Cancers: A Potential Cause for False-Negative Results?

Colorectal (CRCs) and endometrioid (EMCs) cancers in patients with Lynch syndrome exhibit microsatellite instability (MSI) detected by PCR or immunohistochemistry (IHC). While both assays are equally sensitive for CRCs, some suggest that PCR has a higher false-negative rate than IHC in EMCs. We assessed the MSI profiles of 91 EMC and 311 CRC specimens using five mononucleotide repeat markers: BAT25, BAT26, NR21, NR24, and MONO27. EMCs with high MSI (MSI-H) showed a mean left shift of 3 nucleotides (nt), which was significantly different from 6 nt in CRCs. A shift of 1 nt was observed in multiple markers in 76% of MSI-H EMCs, whereas only 12% of MSI-H CRCs displayed a 1-nt shift in one of five markers. IHC against four mismatch repair proteins was performed in 78 EMCs. Loss of staining in one or more proteins was detected in 18 of 19 tumors that were MSI-H by PCR. When EMC tumor cell burden was diluted to <30%, MSI-H was no longer observed in two of three EMCs with a mean nucleotide shift of 1 nt. These results indicate that EMC and CRC MSI profiles are different and that caution should be exercised when interpreting the results, as subtle, 1-nt changes may be missed. These findings provide a potential cause of previously reported discordant MSI and IHC results in EMCs.

UBE2S, a novel substrate of Akt1, associates with Ku70 and regulates DNA repair and glioblastoma multiforme resistance to chemotherapy

Glioblastoma multiforme (GBM) is the most common primary malignant brain cancer in adults. However, the molecular events underlying carcinogenesis and their interplay remain elusive. Here, we report that the stability of Ubiquitin-conjugating enzyme E2S (UBE2S) is regulated by the PTEN/Akt pathway and that its degradation depends on the ubiquitin-proteasome system. Mechanistically, Akt1 physically interacted with and phosphorylated UBE2S at Thr 152, enhancing its stability by inhibiting proteasomal degradation. Additionally, accumulated UBE2S was found to be associated with the components of the non-homologous end-joining (NHEJ) complex and participated in the NHEJ-mediated DNA repair process. The association of Ku70 with UBE2S was enhanced, and the complex was recruited to double-stranded break (DSB) sites in response to etoposide treatment. Furthermore, knockdown of UBE2S expression inhibited NHEJ-mediated DSB repair and rendered glioblastoma cells more sensitive to chemotherapy. Overall, our findings provide a novel drug target that may serve as the rationale for the development of a new therapeutic approach.

Immunohistochemical analysis of the Wnt/β-catenin signaling pathway in pancreatic neuroendocrine neoplasms

AIM: To investigate the role of the Wnt/β-catenin pathway in pancreatic neuroendocrine neoplasms (PanNENs).

METHODS: Tissue microarrays containing 88 PanNENs were immunohistochemically labeled with antibodies to β-catenin, E-cadherin, adenomatous polyposis coli (APC), chromogranin and synaptophysin. One case had only metastatic tumors resected, whereas others (n = 87) received pancreatectomy with or without partial hepatectomy. Pathology slides, demographic, clinicopathologic, and follow up data were reviewed. Patients’ demographics, clinicopathologic features, and immunohistochemical results from 87 primary tumors were compared between patients with low stage (stage I/II) and high stage (stage III/IV) tumors. In addition, correlation of immunohistochemical results from primary tumors with disease-specific survival (DSS) was evaluated.

RESULTS: Strong membranous β-catenin staining in the primary tumor was observed in all 13 stage III/IV PanNENs as compared to 47% (35/74) of stage I/II tumors (P < 0.01). However, the strong membranous β-catenin staining was unassociated with tumor grade or DSS. Decreased membranous β-catenin staining was associated with decreased membranous E-cadherin labeling. Nuclear β-catenin staining was seen in 15% (2/13) of stage III/IV PanNENs as compared to 0% (0/74) of stage I/II tumors (P = 0.02). The case with metastasectomy also only showed nuclear β-catenin staining. Two of the three cases with nuclear β-catenin staining were familial adenomatous polyposis (FAP) patients. Lack of APC expression was seen in 70% (57/81) of the cases, including the 3 cases with nuclear β-catenin staining. Expression of E-cadherin and APC in primary tumor was not correlated with tumor grade, tumor stage, or disease specific survival.

CONCLUSION: The Wnt/β-catenin pathway was altered in some PanNENs, but did not Impact DSS. PanNENs in FAP patients demonstrated nuclear β-catenin accumulation and loss of APC.

A clock network for geodesy and fundamental science

Leveraging the unrivalled performance of optical clocks as key tools for geo-science, for astronomy and for fundamental physics beyond the standard model requires comparing the frequency of distant optical clocks faithfully. Here, we report on the comparison and agreement of two strontium optical clocks at an uncertainty of 5 × 10⁻¹⁷ via a newly established phase-coherent frequency link connecting Paris and Braunschweig using 1,415 km of telecom fibre. The remote comparison is limited only by the instability and uncertainty of the strontium lattice clocks themselves, with negligible contributions from the optical frequency transfer. A fractional precision of 3 × 10⁻¹⁷ is reached after only 1,000 s averaging time, which is already 10 times better and more than four orders of magnitude faster than any previous long-distance clock comparison. The capability of performing high resolution international clock comparisons paves the way for a redefinition of the unit of time and an all-optical dissemination of the SI-second.

Comparing the frequency of two distant optical clocks will enable sensitive tests of fundamental physics. Here, the authors compare two strontium optical-lattice clocks 690 kilometres apart to a degree of accuracy that is limited only by the uncertainty of the individual clocks themselves.

Abstract 2618: Oncogenic mutant KRAS modulates CREB activation through MEK-ERK and AKT signaling in pancreatic cancer

Introduction: Cyclic AMP (cAMP) response element binding (CREB) overexpression in pancreatic ductal adenocarcinoma (PDAC) is associated with poor outcome, however, the mechanism(s) driving CREB overexpression in PDAC are not fully understood. We investigated the association of CREB activation with oncogenic KRAS, MEK-ERK and AKT signaling pathways.

Experimental procedure: Mouse lines derived from the Ptf1aCre/+; LSL-KrasG12D/+ (K518), Ptf1acre/+;LSL-KrasG12D/+;Tgfbr2flox/flox (PKT), LSL-KrasG12D/+;Pdx1Cre/+ (PanIN) and LSL-KrasG12D/+; Trp53R172H/+;Pdx1Cre/+ (PDA) mouse models of PDAC, human immortalized pancreatic ductal epithelial lines (HPDE6-E6E7 or H6c7, HPNE E6/E7 and HPNE E6/E7/KRAS) were immunoblotted for phospho-CREB (pCREB) and total CREB expression. KRAS mutant PDAC cell lines and CREB shRNA flank xenografts (PKT GEMM and nude mice) were treated with CREB (ICG-001), MEK (AZD6244) and AKT (MK-2206) inhibitors. The effects on downstream signaling targets were interrogated with cell cycle, apoptosis, survival and anchorage-independent growth analysis. Human CREB shRNA cells were treated with AZD6244 and MK-2206 to confirm the molecular mechanism of the CREB inhibition together with MEK and AKT.

Results: The expression of pCREB was higher in cells with KRAS mutation. MEK inhibition resulted in activation of AKT, while combined inhibition of CREB and MEK prevented AKT reactivation. Treatment with the combination of MEK and CREB inhibitors significantly decreased tumorigenic potential and increased cell apoptosis. Combined MEK, AKT and CREB inhibition synergistically enhanced these effects further, more so in KRAS mutant cell lines. To explore the relationship of CREB, MEK and AKT signaling in vivo, PKT mice were treated with their respective inhibitors individually and in combination. Either CREB/MEK or CREB/AKT two drug combinations significantly extended the median survival compared with individual agents. Lysates from MEK and AKT inhibited tumors showed decreased phosphorylation of CREB, confirming that CREB is activated through both, MEK and AKT signaling in vivo.

Conclusions: Our study demonstrates that oncogenic KRAS activation enhances the expression of CREB through MEK and AKT signaling. CREB inhibition results in increased sensitivity to MEK and AKT targeted therapy in KRAS mutant PDACs.

Citation Format: Jason Castellanos, Supriya Srinivasan, Kumar Honnenahally, Chanjuan Shi, Michael VanSaun, David Robbins, Nipun Merchant, Nagaraj Nagathihalli. Oncogenic mutant KRAS modulates CREB activation through MEK-ERK and AKT signaling in pancreatic cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2618.

Mutation profiles of synchronous colorectal cancers from a patient with Lynch syndrome suggest distinct oncogenic pathways

Patients with Lynch syndrome often present with multiple synchronous or metachronous colorectal cancers (CRCs). The presence of multiple CRCs with distinct genetic profiles and driver mutations could complicate treatment as each cancer may respond differently to therapy. Studies of sporadic CRCs suggested that synchronous tumors have distinct etiologies, but could not rule out differences in genetic background. The presence of multiple cancers in a patient with a predisposing mutation provides an opportunity to profile synchronous cancers in the same genetic background. Here, we describe the case of a patient with Lynch syndrome that presented with six synchronous CRCs. Microsatellite instability (MSI) and genomic profiling indicated that each lesion had a unique pattern of instability and a distinct profile of affected genes. These findings support the idea that in Lynch syndrome, synchronous CRCs can develop in parallel with distinct mutation profiles and that these differences may inform treatment decisions.

Immunological mechanisms involved in probiotic-mediated protection against Citrobacter rodentium-induced colitis

Inflammatory bowel disease is a group of chronic, incurable inflammatory disorders of the gastrointestinal tract that cause severe diarrhoea, intestinal inflammation, pain, fatigue and weight loss. In this study, we first developed a model of Citrobacter rodentium-induced colitis and then evaluated the protective effects of selected probiotics on inflammation. The results showed that administration of a combination of probiotics including Lactobacillus rhamnosus ATCC 53103, Lactobacillus acidophilus ATCC 4356 and Lactobacillus plantarum A significantly increased the production of CD11c+ dendritic cells in the spleen (3.62% vs phosphate buffered saline (PBS)-treated control, P<0.01) and mesenteric lymph nodes (MLNs). In addition, the presence of probiotics significantly up-regulated the development of CD4+/CD25+/Foxp3+ regulatory T cells in MLNs by approximately 2.07% compared to the effect observed in the PBS-treated control (P<0.01) and down-regulated the expression of inflammatory cytokines, including interleukin-17, tumour necrosis factor-α and interferon-γ, by 0.11, 0.11 and 0.15%, respectively, compared to the effect observed in the PBS-treated control (P<0.01).These effects conferred protection against colitis, as shown by histopathological analyses.

Nodular melanoma in trophic ulceration of a leprosy patient: a case study

Non-healing chronic trophic ulceration is very common in leprosy patients. Marjolin's ulcer consists of the malignant transformation of a chronic ulcerative lesion. Nodular melanoma developing from Marjolin's ulcer, caused by a trophic ulceration of a leprosy patient, is very rare with only a few cases reported in the literature. Due to the disguised presentation of these malignancies within trophic ulceration lesions in leprosy, neoplastic transformation is frequently overlooked, leading to misdiagnosed and delayed treatment. This paper reports a case of an 83-year-old man with lepromatous leprosy and chronic ulceration on the foot for 22 years. Over a period of 2 months, the ulcer enlarged, turned black, and became more painful. The patient underwent regional excision and immunotherapy after the diagnosis of malignant nodular melanoma. After 9 months follow-up, no metastasis was found.

DECLARATION OF INTEREST

There were no external sources of funding for this study. The authors have no conflicts of interest to declare.

Amino acid, phosphorus, and energy digestibility of Aspergillus niger fermented rapeseed meal fed to growing pigs

Fermented rapeseed meal (FRSM) contains greater levels of protein and less glucosinolates, NDF, and phytic acid than rapeseed meal (RSM) and might be an attractive feedstuff for swine, but its nutritional value has been poorly characterized. The aim of this study was to evaluate the nutritional value of RSM fermented by for growing pigs. In Exp. 1, 6 barrows (21.20 ± 1.47 kg initial BW) fitted with a T-cannula in the distal ileum were allotted to a repeated 3 × 3 Latin square with 3 diets and 3 periods per square to determine the apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of CP and AA. A N-free diet and 2 diets containing RSM or FRSM as the only source of AA were formulated. Results indicated that there was no difference in AID and SID of CP and most AA between FRSM and RSM. However, the AID of 2 indispensable AA (Lys and Met) and 3 dispensable AA (Asp, Gly, and Tyr) were greater (P < 0.05) for FRSM than for RSM. The SID of only 2 dispensable AA (Gly and Tyr) were greater (P < 0.05) for FRSM than for RSM. In Exp. 2, 16 barrows (32.57 ± 2.67 kg initial BW) were allotted to 2 diets formulated to contain RSM or FRSM as the sole source of P to determine the apparent total tract digestibility (ATTD) of P. The ATTD and standardized total tract digestibility (STTD) of P in FRSM were 72.10 and 77.31%, respectively. These values were greater (P < 0.01) than in RSM (34.79 and 41.34%, respectively). In Exp. 3, 24 growing barrows (32.23 ± 1.33 kg initial BW) were fed 3 diets with 8 replicate pigs per diet to measure concentration of DE and ME of FRSM. A corn diet consisting of 98.40% corn was formulated and 2 additional diets were formulated by mixing corn with 35% RSM or FRSM. The DE and ME in FRSM (2,887 and 2,650 kcal/kg of DM, respectively) were greater (P < 0.05) than those in RSM (2,609 and 2,328 kcal/kg of DM, respectively). In summary, solid-state fermentation of RSM by has a greater nutritional value than RSM and is a promising alternative high-quality protein source.

Ethanol adaptation induces direct protection and cross-protection against freezing stress in Salmonella enterica serovar Enteritidis

AIMS

Salmonella enterica serovar Enteritidis (Salm. Enteritidis) encounters mild ethanol stress during its life cycle. However, adaptation to a stressful condition may affect bacterial resistance to subsequent stresses. Hence, this work was undertaken to investigate the influences of ethanol adaptation on stress tolerance of Salm. Enteritidis.

METHODS AND RESULTS

Salmonella Enteritidis was subjected to different ethanol adaptation treatments (2·5-10% ethanol for 1 h). Cellular morphology and tolerance to subsequent environmental stresses (15% ethanol, -20°C, 4°C, 50°C and 10% NaCl) were evaluated. It was found that 10% was the maximum ethanol concentration that allowed growth of the target bacteria. Ethanol adaptation did not cause cell-surface damage in Salm. Enteritidis as revealed by membrane permeability measurements and electron micrograph analysis. Salmonella Enteritidis adapted with 2·5-10% ethanol displayed an enhanced resistance to a 15%-ethanol challenge compared with an unchallenged control. The maximum ethanol resistance was observed when ethanol concentration used for ethanol adaptation was increased to 5·0%. Additionally, pre-adaptation to 5·0% ethanol cross-protected Salm. Enteritidis against -20°C, but not against 4°C, 50°C or 10% NaCl.

CONCLUSIONS

Ethanol adaptation provided Salm. Enteritidis direct protection from a high level ethanol challenge and cross-protection from freezing, but not other stresses tested (low temperature, high salinity or high temperature).

SIGNIFICANCE AND IMPACT OF THE STUDY

The results are valuable in developing adequate and efficient control measures for Salm. Enteritidis in foods.

BRAF mutations in colonic high-grade neuroendocrine carcinoma

612

Background: The WHO 2010 has classified GI neuroendocrine neoplasms into well-differentiated neuroendocrine tumor (NET) and high-grade neuroendocrine carcinoma (NEC). NEC is more aggressive than NET. Whole genome sequencing (WGS) has provided insight into the genetic underpinnings of NET but little is known about NEC. The aim of this study is to perform genomic profiling of NEC to better characterize the underlying mutations in this aggressive disease. Methods: We identified 9 patients who underwent biopsy or resection for NEC between 1/2005 - 6/2013 with histological blocks available. WGS was performed on DNA extracted from tissue from 2 patients with ≥80% tumor cellularity using the Illumina HiSeq 2500 platform. Validation and mutational analysis of the BRAF gene was performed on 2 WGS patients and an additional 7 patients via Sanger Sequencing of exon 11 and 15. Results: 7 of 9 patients (78%) presented with metastasis at initial diagnosis (Table). 8 patients died of disease within 25 months. In 2 NECs, we identified BRAF mutations on exon 15 by WGS. Patient S1 presented with cecal NEC and had an A1781G:p.D594G mutation on exon 15. Patient S2 presented with a descending colon NEC and had a c.1799T>A: p.V600E mutation on exon 15. An additional 7 colonic NECs were analyzed with Sanger Sequencing of exons 11 and 15. 2 had BRAFV600E mutations. Overall, BRAF mutations were present in 4 of 9 (44%) colonic NECs. The 3 cases with V600E mutations were large cell NECs, whereas the case with a D594G mutation was a small cell NEC. Conclusions: High grade colonic NEC is an aggressive tumor with high frequency (44%) of activating BRAF mutations. Further investigation is warranted to ascertain the incidence of BRAF mutations in a larger population as BRAF inhibition may be a potential avenue of targeted treatment for these patients. [Table: see text]

Could the PD-1 pathway be a potential target for treating small intestinal adenocarcinoma?

233

Background: The programmed death 1 (PD-1) pathway is up-regulated in the immune microenvironment of many cancers. PD-1 blockage has been shown to be effective in treating some malignancies. In colorectal cancers, inhibition of PD-1 pathway appears to be selectively efficacious in microsatellite instable (MSI) tumors. In this study, we examined the immune microenvironment of small intestinal adenocarcinoma by immunohistochemistry. Methods: Twenty two small intestinal adenocarcinomas were identified from our Pathology Archives from 01/01/2002 to 05/01/2014. Immunohistochemical studies were employed to evaluate expression of CD3, CD4, CD8, CD20, CD56, PD-1 and programmed death ligand 1 (PD-L1). CD3+, CD4+, and CD8+ T cells were estimated under high power fields (HPF) and compared between PD-L1+ and PD-L1- tumors. Results: The 22 cases included 9 females and 13 males, with age ranging from 38 to 92 years. PD-1 was expressed in 18 of 22 (82%) cases, by tumor surrounding lymphocytes and lymphoid aggregates as well as tumor infiltrating lymphocytes if present. PD-L1 expression was observed in 10 of 22 (45%) cases, including 2 MSI, 2 microsatellite stable (MSS) and 6 tumors with unknown MSI status. PD-L1 was mainly expressed by histiocytes capping cancerous glands/nests at the infiltrating front. Expression of PD-L1 was also seen in tumor cells surrounding by the histiocytic caps. All the 10 cancers also expressed PD-1. The tumors expressing PD-L1 contained more CD3+ (440±22/HPF versus 238±31/HPF, p < 0.01), CD4+ (172±26/HPF versus 287±25/HPF, p < 0.01) and CD8+ T cells (58±17/HPF versus 153±33/HPF, p = 0.013) than those without expression of PD-L1. CD20+ cells were mainly seen in lymphoid aggregates. There were rare or none C56+ inflammatory cells. Conclusions: PD-1 and PD-L1 are expressed by inflammatory cells (mainly histiocytes) and tumors cells in most small intestinal adenocarcinoma. Blockage of the PD-1 pathway should be evaluated in the treatment of small intestinal adenocarcinomas.

Safety and Efficacy of 68Ga-DOTATATE PET/CT for Diagnosis, Staging, and Treatment Management of Neuroendocrine Tumors

Our purpose was to evaluate the safety and efficacy of (68)Ga-DOTATATE PET/CT compared with (111)In-pentetreotide imaging for diagnosis, staging, and restaging of pulmonary and gastroenteropancreatic neuroendocrine tumors.

METHODS

(68)Ga-DOTATATE PET/CT and (111)In-pentetreotide scans were obtained for 78 of 97 consecutively enrolled patients with known or suspected pulmonary or gastroenteropancreatic neuroendocrine tumors. Safety and toxicity were measured by comparing vital signs, serum chemistry values, or acquisition-related medical complications before and after (68)Ga-DOTATATE injection. Added value was determined by changes in treatment plan when (68)Ga-DOTATATE PET/CT results were added to all prior imaging, including (111)In-pentetreotide. Interobserver reproducibility of (68)Ga-DOTATATE PET/CT scan interpretation was measured between blinded and nonblinded interpreters.

RESULTS

(68)Ga-DOTATATE PET/CT and (111)In-pentetreotide scans were significantly different in impact on treatment (P < 0.001). (68)Ga-DOTATATE PET/CT combined with CT or liver MRI changed care in 28 of 78 (36%) patients. Interobserver agreement between blinded and nonblinded interpreters was high. No participant had a trial-related event requiring treatment. Mild, transient events were tachycardia in 1, alanine transaminase elevation in 1, and hyperglycemia in 2 participants. No clinically significant arrhythmias occurred. (68)Ga-DOTATATE PET/CT correctly identified 3 patients for peptide-receptor radiotherapy incorrectly classified by (111)In-pentetreotide.

CONCLUSION

(68)Ga-DOTATATE PET/CT was equivalent or superior to (111)In-pentetreotide imaging in all 78 patients. No adverse events requiring treatment were observed. (68)Ga-DOTATATE PET/CT changed treatment in 36% of participants. Given the lack of significant toxicity, lower radiation exposure, and improved accuracy compared with (111)In-pentetreotide, (68)Ga-DOTATATE imaging should be used instead of (111)In-pentetreotide imaging where available.

Bifunctional alloys for the electroreduction of CO2and CO

We use density functional theory to study the reduction of CO₂and CO to hydrocarbons through a formyl pathway on (111) and (211) facets of L1₂alloys with an A₃B composition.

Loss of Lrig1 leads to expansion of Brunner glands followed by duodenal adenomas with gastric metaplasia

Leucine-rich repeats and immunoglobulin-like domains 1 (LRIG1) is a pan-ErbB negative regulator and intestinal stem cell marker down-regulated in many malignancies. We previously reported that 14 of 16 Lrig1-CreERT2/CreERT2 (Lrig1(-/-)) mice developed duodenal adenomas, providing the first in vivo evidence that Lrig1 acts as a tumor suppressor. We extended this study to a larger cohort and found that 49 of 54 Lrig1(-/-) mice develop duodenal adenomas beginning at 3 months. Most adenomas were histologically low grade and overlaid expanded Brunner glands. There was morphologic and biochemical blurring of the boundary between the epithelium and Brunner glands with glandular coexpression of ErbB2, which is normally restricted to the epithelium, and the Brunner gland marker Mucin6. Some adenomas were high grade with reduced Brunner glands. At age 4 to 5 weeks, before adenoma formation, we observed enhanced proliferation in Brunner glands and, at 2 months, an increase in the size of the Brunner gland compartment. Elevated expression of the epidermal growth factor receptor (Egfr) ligands amphiregulin and β-cellulin, as well as Egfr and phosphorylated Egfr, was detected in adenomas compared with adjacent normal tissue. These adenomas expressed the gastric-specific genes gastrokine1 and mucin5ac, indicating gastric metaplasia. Moreover, we found that a subset of human duodenal tumors exhibited features of LRIG1(-/-) adenomas, including loss of LRIG1, gastric metaplasia (MUCIN5AC and MUCIN6), and increased amphiregulin and Egfr activity.

Signal Transducer and Activator of Transcription 3, Mediated Remodeling of the Tumor Microenvironment Results in Enhanced Tumor Drug Delivery in a Mouse Model of Pancreatic Cancer

BACKGROUND & AIMS

A hallmark of pancreatic ductal adenocarcinoma (PDAC) is the presence of a dense desmoplastic reaction (stroma) that impedes drug delivery to the tumor. Attempts to deplete the tumor stroma have resulted in formation of more aggressive tumors. We have identified signal transducer and activator of transcription (STAT) 3 as a biomarker of resistance to cytotoxic and molecularly targeted therapy in PDAC. The purpose of this study is to investigate the effects of targeting STAT3 on the PDAC stroma and on therapeutic resistance.

METHODS

Activated STAT3 protein expression was determined in human pancreatic tissues and tumor cell lines. In vivo effects of AZD1480, a JAK/STAT3 inhibitor, gemcitabine or the combination were determined in Ptf1a(cre/+);LSL-Kras(G12D/+);Tgfbr2(flox/flox) (PKT) mice and in orthotopic tumor xenografts. Drug delivery was analyzed by matrix-assisted laser desorption/ionization imaging mass spectrometry. Collagen second harmonic generation imaging quantified tumor collagen alignment and density.

RESULTS

STAT3 activation correlates with decreased survival and advanced tumor stage in patients with PDAC. STAT3 inhibition combined with gemcitabine significantly inhibits tumor growth in both an orthotopic and the PKT mouse model of PDAC. This combined therapy attenuates in vivo expression of SPARC, increases microvessel density, and enhances drug delivery to the tumor without depletion of stromal collagen or hyaluronan. Instead, the PDAC tumors demonstrate vascular normalization, remodeling of the tumor stroma, and down-regulation of cytidine deaminase.

CONCLUSIONS

Targeted inhibition of STAT3 combined with gemcitabine enhances in vivo drug delivery and therapeutic response in PDAC. These effects occur through tumor stromal remodeling and down-regulation of cytidine deaminase without depletion of tumor stromal content.

Virtual classroom helps medical education for both Chinese and foreign students

AIMS

The rapid development of computer and internet technology has a strong influence over one's quality of education within different fields of study. To determine the potential benefits of introducing internet into medical school classes, a pilot study was conducted in three different Chinese medical schools.

MATERIALS AND METHODS

Seven hundred and eight medical school undergraduates, 385 dental school students and 366 foreign students were randomly recruited to complete a self-administered questionnaire. The contents included personal information, current usage of computer and internet, and attitudes towards the computerised teaching methods. Two forum groups were created using instant message software and were randomly assigned to two classes, allowing students to freely ask or discuss questions with the help of their teachers in these two virtual classrooms.

RESULTS

All 1539 questionnaires were accepted and analysed. Although there were some differences between Chinese and foreign undergraduates, both group of students were highly proficient in internet usage and navigation. Overwhelmingly, 88.37% of the students owned a computer and frequently logged onto the internet. Most of them believed that the internet is a helpful adjunct to their studies and held positive attitudes towards computerised teaching. Compared to the classes that were not assigned internet forums, the two experimental classes performed significantly better on the examination.

CONCLUSIONS

Our results suggest that computerised teaching methods have significant potential to assist in learning for both Chinese and foreign medical undergraduates.

Expression of CD24, a Stem Cell Marker, in Pancreatic and Small Intestinal Neuroendocrine Tumors

OBJECTIVES

CD24 has been considered a normal and cancer stem cell marker. Potential intestinal stem cells weakly express CD24. In the pancreas, CD24 is a possible cancer stem cell marker for ductal adenocarcinoma.

METHODS

Expression of CD24 in intestinal and pancreatic neuroendocrine tumors (NETs) was examined. Immunohistochemistry was performed on benign duodenum, ileum mucosa, and pancreas, as well as primary duodenal, primary and metastatic ileal, and pancreatic NETs.

RESULTS

Scattered CD24-positive cells were noted in the duodenal and ileal crypts, most of which showed a strong subnuclear labeling pattern. Similar expression was observed in 41 (95%) of 43 primary ileal NETs but in only four (15%) of 26 duodenal NETs (P < .01). In addition, metastatic ileal NETs retained CD24 expression. Pancreatic islets did not express CD24, and only rare cells had subnuclear labeling of CD24 in the pancreatic ducts. Unlike ileal NETs, only five (5%) of 92 pancreatic NETs expressed CD24 in the subnuclear compartment (P < .01). All five NETs showed a unique morphology with prominent stromal fibrosis.

CONCLUSIONS

CD24 expression was frequent in primary and metastatic midgut NETs but rare in pancreatic and duodenal NETs. Expression of CD24 in ileal NETs may have future diagnostic and therapeutic implications.

Abstract 2000: Proteomic features of histological compartments in colorectal carcinoma

Proteomic analysis of cancer tissues by mass spectrometry (MS) is complicated by the fact that histological context is lost in the analysis. Knowledge on the abundance of key proteins for the different histological compartments may allow an assessment of the contribution of each of these components to the proteomic profile obtained. We studied 18 colorectal carcinoma specimens and isolated carcinoma, necrosis, normal epithelium, stroma, smooth muscle, and lymphoid infiltrate compartments using laser capture microdissection (LCM). Proteins extracted from 60 LCM caps were subjected to short-stack, gel electrophoresis, in-gel trypsin digestion and analyzed on a Thermo-Fisher QExactive Orbitrap MS instrument. Data were searched using myrimatch and MS-GF+ on a RefSeq protein database and identified proteins were assembled using IDpicker 3. The analysis identified about 2,000 non-redundant proteins at a protein FDR&lt;5%. Unsupervised cluster analysis of the most abundant proteins clustered each of the compartments together with few exceptions. Surprisingly, the necrotic compartment was almost identical from the carcinoma compartment, indicating the stability of the small peptides used for MS sequence identifications. Comparisons of spectral count data between each of the compartments and the remainder of the dataset by protein enrichment analyses was performed using the online tool www.webgestalt.org. The carcinoma compartment was enriched for proteins involved in nucleic acid and general metabolism processes. Smooth muscle was enriched for proteins involved in muscle contraction and cell adhesion. The lymphoid infiltrates were enriched for chromatin and nucleosome proteins, possibly indicating the relative contribution of nuclear proteins from these small cells. The stromal component was enriched for extracellular matrix proteins and proteins involved in glycosylation processes. Using data from ProteinAtlas.org, we confirmed histological associations of the most prominent protein markers with their respective histological component. For instance, COL12A1 was highly expressed in the stromal compartment, while SMTN was highly specific for smooth muscle. Expression levels characterizing each of the histological components can thus be described in protein signatures that can serve as a measure of the relative contribution of each of the components in the complex composition of a colorectal carcinoma sample.

Supported by NIH/NCI grant U24CA159988.

Citation Format: Robbert JC Slebos, Lisa J. Zimmerman, Suzanne Manning, Melinda E. Sanders, Chanjuan Shi, M Kay Washington, Daniel C. Liebler. Proteomic features of histological compartments in colorectal carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2000. doi:10.1158/1538-7445.AM2015-2000

Abstract 924: GM-CSF induces CREB signaling pathways and modulates tobacco carcinogen-induced pancreatic tumorigenesis

Introduction: Nicotine and nitrosamine exposure from smoking causes pancreatic cell injury and contributes to a cascade of oncogenic events that may be contributing to the rising rate of pancreatic cancer (PDAC). Cytokines activate kinases and transcription factors including cyclic AMP response element binding (CREB) protein. CREB activation through phosphorylation regulates diverse cellular responses. We studied whether granulocyte-macrophage colony stimulating factor (GM-CSF)-dependent phosphorylated CREB plays a role in smoking-induced pathogenesis of PDAC.

Experimental procedure: Human tissue microarray analysis was performed to determine the significance of pCREB expression amongst smokers and non-smokers. Total RNA extracted from immortalized human pancreatic ductal cell (H6c7) and pancreatic intraepithelial neoplasia (PanIN) mouse cell lines (LSL-KrasG12D/+; Pdx1Cre/+) were treated with tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and RNA sequencing (RNA-seq) was performed. Network, pathway and functional analyses of the transcriptome were conducted. To analyze the signaling pathway involved in NNK-induced tumorigenicity, we performed a phospho-kinase antibody array and cytokine antibody array on NNK treated H6c7 and PanIN cells or conditioned media (CM) protein. Western blot and ELISA were used to validate the array data findings. NNK-induced activation of GM-CSF, G-CSF and IL-6 were blocked using monoclonal antibodies. PKT (Ptf1acre/+;LSL-KrasG12D/+;Tgfbr2flox/flox) mice and nude mice with MiaPaCa2 flank xenografts were treated with MEK inhibition (AZD6244) with or without NNK/in vivo smoking. Tumors from these mice were immunoblotted for phosphorylation of MEK1/2, MSK1/2, RSK and CREB. PDAC cells with CREB siRNA or human rGM-CSF were treated with NNK and analyzed for in vitro functional assays and EMT characteristics.

Results: Expression of pCREB was significantly higher (p&lt;0.001) in smokers when compared to non-smokers. Overall survival of smokers with high pCREB expression in their primary tumor was associated with significantly decreased median survival when compared to non-smokers with low pCREB expression. Exposure of cells to NNK resulted in phosphorylation of CREB, c-Jun and β-catenin, and release of GM-CSF, G-CSF and IL-6. RNA-seq analysis confirmed activation of MEK/ERK signaling. Studies were performed to elucidate the possible regulatory mechanism behind NNK mediated induction of GM-CSF and its downstream signaling. Importantly, blocking GM-CSF inhibited NNK-induced phosphorylation of CREB and it was mediated through MEK signaling. The in vivo and in vitro tumorigenicity assays showed an increase in the tumorigenic potential and EMT of NNK treated PDAC cells.

Conclusions: Our study demonstrates that NNK induces pancreatic tumorigenesis through GM-CSF mediated activation of CREB.

Citation Format: Jason Castellanos, Kumaraswamy Honnenahally, Chanjuan Shi, Nipun Merchant, Nagaraj Nagathihalli. GM-CSF induces CREB signaling pathways and modulates tobacco carcinogen-induced pancreatic tumorigenesis. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 924. doi:10.1158/1538-7445.AM2015-924

Inhalation of recombinant adenovirus expressing granulysin protects mice infected with Mycobacterium tuberculosis

Granulysin is a cytolytic molecule with perforin and granzymes that is expressed by activated human CTLs, NK and γδ T cells, and it has broad antimicrobial activity, including to drug-sensitive and drug-resistant Mycobacterium tuberculosis. We hypothesized that approaches facilitating the expression of granulysin in M. tuberculosis-infected host cells in the lung may provide a novel treatment strategy for pulmonary TB. In this study, a recombinant replication-deficient adenovirus serotype 5-based rAdhGLi was constructed that expressed human granulysin in the cytosol of the U937 and RAW264.7 macrophage-like cell lines as confirmed by western blotting and co-localization technology using indirect immunofluorescence staining. Ninety-six hours after both cell lines were infected with M. tuberculosis, acid-fast staining and enumeration demonstrated that rAdhGLi-treated cells had a lower colony-forming units (CFU) of intracellular bacteria than culture medium or AdNull controls. Granulysin was only expressed in the lung and not in other organs following inhalation of rAdhGLi. In particular, immunocompetent BALB/c mice or SCID mice intranasally infected with ~200 CFU of virulent M. tuberculosis H37Rv intranasally were treated with rAdhGLi, and they showed decreased bacterial loads in the lung when compared with phosphate-buffered saline or AdNull controls. Importantly, a clear dose-dependent rAdhGLi treatment efficacy was found in infected BALB/c mice, with the most significant reduction in lung bacteria obtained in BALB/c mice treated with 10(9) plaque-forming units of rAdhGLi without any pathological changes. Our study indicates that rAdhGLi may be used as a novel and efficient treatment strategy with the capability to directly kill intracellular M. tuberculosis.

Treatment of Benign Thyroid Nodules: Comparison of Surgery with Radiofrequency Ablation

BACKGROUND AND PURPOSE

Nodular goiter is one of the most common benign lesions in thyroid nodule. The main treatment of the disease is still the traditional surgical resection, however there are many problems such as general anesthesia, surgical scar, postoperative thyroid or parathyroid function abnormalities, and high nodules recurrence rate in residual gland. The purpose of this study was to compare the efficacy, safety, and cost-effectiveness of 2 treatment methods, surgery and radiofrequency ablation, for the treatment of benign thyroid nodules.

MATERIALS AND METHODS

From May 2012 to September 2013, 200 patients with nodular goiters who underwent surgery (group A) and 200 patients treated by radiofrequency ablation (group B) were enrolled in this study. Inclusion criteria were the following: 1) cosmetic problem, 2) nodule-related symptoms, 3) hyperfunctioning nodules related to thyrotoxicosis, and 4) refusal of surgery (for group B). An internally cooled radiofrequency ablation system and an 18-ga internally cooled electrode were used. We compared the 2 groups in terms of efficacy, safety, and cost-effectiveness during a 1-year follow-up.

RESULTS

After radiofrequency ablation, the nodule volume decreased significantly from 5.4 to 0.4 mL (P = .002) at the 12-month follow-up. The incidence of complications was significantly higher from surgery than from radiofrequency ablation (6.0% versus 1.0%, P = .002). Hypothyroidism was detected in 71.5% of patients after surgery but in none following radiofrequency ablation. The rate of residual nodules (11.9% versus 2.9%, P = .004) and hospitalization days was significantly greater after surgery (6.6 versus 2.1 days, P < .001), but the cost difference was not significant.

CONCLUSIONS

Surgical resection and radiofrequency ablation are both effective treatments of nodular goiter. Compared with surgery, the advantages of radiofrequency ablation include fewer complications, preservation of thyroid function, and fewer hospitalization days. Therefore, radiofrequency ablation should be considered a first-line treatment for benign thyroid nodules.

Emergence of a new GII.17 norovirus variant in patients with acute gastroenteritis in Jiangsu, China, September 2014 to March 2015

From September 2014 to March 2015, 23 outbreaks of norovirus (NoV) acute gastroenteritis occurred in Jiangsu, China. Partial sequencing of the NoV capsid gene suggested that 16 of the 23 outbreaks were related to a new GII.17 variant. This variant was first detected in sporadic specimens in October 2014, and became predominant in February 2015. Analysis of the RNA-dependent RNA polymerase (RdRp), and complete capsid including the protruding domain P2 sequences confirmed this GII.17 variant as distinct from previously identified GII variants.