Cellular stress response in Eca-109 cells inhibits apoptosis during early exposure to isorhamnetin

The flavonol aglycone isorhamnetin shows anti-proliferative activity in a variety of cancer cells. Previous work, from our laboratory showed that isorhamnetin inhibits the proliferation of human esophageal squamous carcinoma Eca-109 cells in vitro, but only after 72 h of exposure. This led us to propose that isorhamnetin exposure induces a cellular stress response that inhibits the antiproliferative and apoptotic effects of the compound during early exposure. To test this hypothesis, the present study examined the effects of isorhamnetin on Eca-109 cells during the first 72 h of exposure. Cell growth was assessed using the trypan blue exclusion assay, and expression of IκBα, NF-κB/p65, NF-κB/p50, phospho-Akt, Bcl-2, COX-2, Mcl-1, Bax, p53 and Id-1 were analyzed by Western blot. During the first 72 h of exposure, NF-κB/p65 and NF-κB/p50 accumulated in nuclei and expression of COX-2, Bcl-2 and Mcl-1 increased. In contrast, expression of IκBα and Bax fell initially but later increased. Expression of phospho-Akt and p53 showed no detectable change during the first 48 h. Pretreatment with the NF-κB inhibitor MG132 before exposure to isorhamnetin blocked the nuclear accumulation of p50 and p65, thereby inhibiting cell proliferation. These results show that during early exposure of Eca-109 cells to isorhamnetin, the NF-κB signaling pathway is activated and COX-2 expression increases, and this increase in expression partially inhibits isorhamnetin-induced apoptosis. Beyond 72 h of exposure, however, the apoptotic effect of isorhamnetin dominates, leading to inhibition of the NF-κB pathway and of cellular proliferation. These results will need to be taken into account when exploring the use of isorhamnetin against cancer in vivo.

Molecular testing in colorectal cancer: diagnosis of Lynch syndrome and personalized cancer medicine

Currently, molecular testing in colorectal cancer (CRC) is aimed at detecting Lynch syndrome and predicting response to anti-epidermal growth factor receptor (EGFR) therapies. However, CRC is a complex disease, with at least 3 molecular pathways of carcinogenesis. The importance of the EGFR signaling pathway in colorectal carcinogenesis is underscored by the availability of anti-EGFR monoclonal antibodies for the treatment of some metastatic CRCs. Potentially, mutations in any of the genes in the EGFR signaling pathway may be associated with prognosis and may predict response to anti-EGFR or other targeted therapies. Although not currently the standard of care, molecular testing of CRCs is expanding to include mutational analysis of the genes in the EGFR pathway, in addition to more widely performed tests for identifying cancers with high microsatellite instability. Multiplex molecular prognostic panels for therapeutic decision making in stage II CRCs also represent expanding use of molecular testing for this common cancer.

Leveraging bimodal kinetics to improve detection specificity

Optical microcavities are high sensitivity transducers able to detect single nanoparticles and molecules. However, the specificity of detection is dependent on the availability of an appropriate targeting moiety with minimal cross-reactivity. In the present work, an alternative approach is shown. Namely, using biotin-functionalized toroidal microcavities, the dissociation constant of biotin to two different streptavidin complexes (free and polystyrene bead) is determined. Based on the difference in affinity and in mass transport, the two complexes are identified from a mixture. By leveraging information in the binding site, improved specificity can be achieved.

Variable expression of somatostatin receptor type 2 in metastatic midgut carcinoid

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Background: Somatostatin receptor type 2 (SSTR2) is frequently highly expressed in carcinoid tumors of the midgut. The presence of the receptor is the basis of imaging and therapeutics. Because of the high dependence of clinical care on SSTR2, we evaluated the immunohistochemical staining of specimens and correlated with clinical parameters.

Methods: A tissue microarray (TMA) of 1 mm cores from paraffin embedded specimens of surgically resected midgut carcinoid were created with primary, lymph node, and liver metastatic lesions. These sections were stained by immunohistochemistry with anti-SSTR2 antibody, and scored on staining intensity. Sections were evaluated by membrane (0-none, 1 – weak, 2 – partial, 3- complete) and cytoplasmic (strong vs. weak) staining.

Results: Thirty-five patient samples were included in the TMA. There were a total of 62 cores embedded: 21 primary lesions, 26 lymph node metastases, and 15 liver metastases. The total disease burden was captured in 17 patients, and specimens from all three sites were captured in 6 patients. Of the thirty-five patients, 6 had consistently weak SSTR2 staining (17% either 0 or 1). One of these cases had an intermediate grade tumor with Ki67 >20%. Of the patients where more than one location was captured, 19/21 (90%) had consistent SSTR2 staining at all sites. Most cases had strong staining in the membrane (69%) while a minority had strong cytoplasmic staining (31%). Of the patients with weak SSTR2 membrane staining, 2 still had positive octreoscans. Clinically, most patients had good outcomes and 94% are still alive. Eight cases had carcinoid carcinomatosis (23%). Of the six with weak membrane staining, three had carcinomatosis (50%), while only 5/30 (17%) with strong membrane staining had carcinomatosis.

Conclusions: While the majority of small bowel carcinoids and their metastatic lesions have strong SSTR2 staining, not all do. However, even in cases with low amounts of SSTR2 on the membrane, the tumors can still be detected on octreoscan, demonstrating the effect of receptor turnover. The loss of SSTR2 may be associated with more advanced disease, but is not completely predictive.

Correlation between Thyroid Nodule Calcification Morphology on Ultrasound and Thyroid Carcinoma

OBJECTIVE: This study investigated the detection of thyroid nodule calcifications on ultrasound and their relationship to thyroid carcinoma. METHODS: Microcalcifications (≤ 2 mm) and macrocalcifications (> 2 mm) on preoperative ultrasound examination of thyroid and lymph nodes were compared with postoperative pathological diagnoses in 4186 patients undergoing thyroid surgery. RESULTS: Higher incidences of micro- and macrocalcifications were found in patients with thyroid carcinoma than in those with benign disease. The incidence of malignant disease was significantly higher in patients with microcalcifications than those with macrocalcifications, suggesting that the presence of microcalcifications is a better predictor of malignant thyroid carcinoma than other calcification types. The specificity of microcalcifications for a diagnosis of malignant thyroid carcinoma was 96.5%. Microcalcifications were significantly more frequent in patients aged ≤ 45 years, but there was no difference between genders. The incidence of malignancy was significantly higher in patients with single nodule calcifications than in those with multiple nodule calcifications. Lymph node calcifications were seen in 12 patients, all of whom had papillary carcinoma. CONCLUSIONS: Thyroid microcalcifications are strongly associated with thyroid carcinoma, especially micropapillary carcinoma. When cervical lymph node calcification is present, immediate surgery is required.

Relationship of STAT3-mediated treatment resistance on activated MAPK signaling in pancreatic cancer

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Background: Pancreatic ductal adenocarcinoma (PDAC) is one of the most difficult human malignancies to treat due to its intrinsic (de novo) and extrinsic (acquired) chemoresistance. We have previously identified constitutively activated STAT3 as a mediator of treatment resistance. Src or EGFR activate STAT3 and promote STAT3 mediated tumor progression and mediate communication within the tumor microenvironment (TME). The purpose of this study was to further understand the molecular mechanisms of stromal-mediated chemoresistance in PDAC to generate new and promising targeted therapies.

Methods: We characterized the expression of total and activated STAT3 and MAPK proteins in human pancreatic tissues (n=106), PDAC cell lines (n=9) and in PanIn lesions, primary PDAC and liver metastasis cell lines generated from tumors established in genetically engineered mice. Effects of STAT3 and MAPK inhibition (drug or siRNA) were assessed for phosphorylation of STAT3, Src, MAPK, EGFR and GSK3β and expression of cyclin-D1, SPARC, VEGF, fibronectin, CD31 and tumorigenicity in vitro and in vivo.

Results: STAT3 activation is necessary for the malignant phenotype and affects survival in PDAC. In both human and mouse PDAC cell lines and tissues, there is an inverse correlation between activation of STAT3 on MAPK and GSK3β signaling. Inhibition of STAT3 reciprocally activated MAPK, GSK3β, Src and EGFR which led to subsequent reactivation of STAT3. Targeting both STAT3 and MAPK inhibited activation of STAT3, MAPK, GSK3β, Src, EGFR and cyclin-D1. Combined inhibition of STAT3 and MAPK overcame STAT3 mediated resistance and resulted in synergistic inhibition of tumorigenicity as well as inhibition of the tumor stroma, angiogenesis and hypoxia within the TME.

Conclusions: The mechanism of STAT3-mediated treatment resistance is dependent on activation of MAPK signaling which in turn leads to reactivation of multiple oncogenic signaling pathways. Combined inhibition of STAT3 and MAPK overcomes therapeutic resistance, targets the TME and reduces tumorigenicity in PDAC. Targeting STAT3 and MAPK is a potent treatment regimen and may be a novel approach to enhance drug delivery and improve therapeutic response in PDAC.

Use of the monoclonal antibody PAM4 to differentiate pancreatic ductal adenocarcinoma (PDAC) from chronic pancreatitis and benign nonmucinous cysts of the pancreas

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Background: Previous studies have demonstrated that anti-mucin monoclonal antibody (mAb) PAM4 is highly specific for PDAC and its precursor lesions. To investigate specificity further, we examined the expression of PAM4-reactive mucin in chronic pancreatitis and benign non-mucinous cystic lesions of the pancreas.

Methods: A tissue microarray of PDAC (N=14), as well as surgical specimens from chronic pancreatitis (N=32) and benign non-mucinous cystic lesions of the pancreas (N=19), were assessed by immunohistochemistry for expression of the PAM4-reactive mucin, as well as MUC1 (mAb-MA5), MUC4 (mAb-8G7), and CEACAM6 (mAb-MN-15).

Results: PAM4-reactive mucin, MUC1, MUC4 and CEACAM6 were expressed in 79% (11/14), 100% (14/14), 86% (12/14) and 100% (14/14) of invasive pancreatic adenocarcinoma. PAM4 only weakly labeled 6% (1/19) of benign non-mucinous cystic lesions, 1 of 15 serous cystadenomas (SCAs) and 0 of 4 cysts with squamous epithelial lining (2 lymphoepithelial cysts, and 2 retention cysts with squamous metaplasia). However, the expression of MUC1, MUC4 and CEACAM6 was detected in 53% (8/15), 0% (0/15) and 13% (2/15) of SCAs, and in 4, 3 and 3 of the 4 cysts with squamous epithelial lining, respectively. PAM4 labeled 19% (6/32) of chronic pancreatitis specimens; however, this PAM4 reactivity was restricted to the PanIN precursor lesions associated with chronic pancreatitis. Inflamed tissue was negative. The expression of MUC1, MUC4 and CEACAM6 was detected in 90% (27/30), 78% (25/32), and 97% (31/32) of chronic pancreatitis. In all of the positively-labeled specimens, the reactivity was present in non-neoplastic inflamed pancreatic tissue in addition to PanIN.

Conclusions: The expression of PAM4 was detected in only 6% of benign non-mucinous cystic lesions and in the precursor lesions associated with chronic pancreatitis. These results suggest that PAM4, in contrast to MUC1, MUC4, and CEACAM6, may be useful to differentiate benign non-mucinous cystic lesions of the pancreas and chronic pancreatitis from PDAC. (Supported in part by NIH grant CA096924.)

Serotonin expression in pancreatic neuroendocrine tumors correlates with a trabecular histologic pattern and large duct involvement

Pancreatic neuroendocrine tumors with prominent stromal fibrosis are often clinically, radiographically, and grossly indistinguishable from ductal adenocarcinoma. We recently described a small series of fibrotic pancreatic neuroendocrine tumors that express serotonin. To understand better the relationship between histopathologic patterns and serotonin expression, we reviewed 361 pancreatic neuroendocrine tumors to identify those with prominent stromal fibrosis exceeding 30% of total tumor area. We identified 52 cases and immunolabeled these neoplasms with antibodies to serotonin and Ki-67. Two predominant histologic subtypes were identified: 14 (26.9%) of 52 had a trabecular or trabecular-glandular cellular pattern with interspersed fibrosis, whereas 38 (73.1%) of 52 had solid architecture. Of the 52, 14 (26.9%) pancreatic neuroendocrine tumors showed at least focal serotonin immunoreactivity. Tumors with predominantly trabecular architecture were significantly more likely to express serotonin than those with solid architecture (P < .01). Only 2 of 34 pancreatic neuroendocrine tumors with fibrosis less than 30% of total tumor area expressed serotonin. The 14 serotonin-expressing tumors were less likely to have lymph node metastases (P = .016) and more likely to involve large pancreatic ducts (P < .01) than were the 38 serotonin-negative tumors. The serotonin-expressing tumors were also found in a younger patient population (P < .01). There was no significant association of serotonin immunoreactivity with Ki-67 proliferation index, tumor size, or distant metastases. Our data demonstrate a strong correlation between trabecular architecture and serotonin immunoreactivity in pancreatic neuroendocrine tumors with stromal fibrosis. Serotonin-expressing tumors are also less likely to have lymph node metastases and more likely to involve large pancreatic ducts.

Altered telomeres in tumors with ATRX and DAXX mutations

The proteins encoded by ATRX and DAXX participate in chromatin remodeling at telomeres and other genomic sites. Because inactivating mutations of these genes are common in human pancreatic neuroendocrine tumors (PanNETs), we examined the telomere status of these tumors. We found that 61% of PanNETs displayed abnormal telomeres that are characteristic of a telomerase-independent telomere maintenance mechanism termed ALT (alternative lengthening of telomeres). All of the PanNETs exhibiting these abnormal telomeres had ATRX or DAXX mutations or loss of nuclear ATRX or DAXX protein. ATRX mutations also correlate with abnormal telomeres in tumors of the central nervous system. These data suggest that an alternative telomere maintenance function may operate in human tumors with alterations in the ATRX or DAXX genes.

Mitochondrial apoptotic pathways: a mechanism for low androgen-induced vascular endothelial injury in male rats

The aim of the study was to investigate the role of mitochondrial apoptotic pathways in vascular endothelial injury in male rats with low androgen. 8 week-old adult male Sprague-Dawley (SD) rats were randomly divided into 3 groups (n=6/each group): control group, castrated group (low androgen), and replacement group (given androgen after castration). After 10 weeks, endothelial structure was observed by general light microscope and transmission electron microscope (TEM) respectively. Isolated mitochondria and mitochondrial membrane potential (MMP) were detected by fluorescence to access mitochondrial function. Chromatin degradation was measured by terminal deoxynucleotidyl transferase-mediated deoxyuridine-biotin nick end labeling (TUNEL) staining method. The mRNA and protein of bcl-2, cytochrome C (Cyt C), caspase-9, and caspase-3 were analyzed for apoptosis. Cell shrinkage and condensed chromatin, less mitochondria and a fall in MMP levels were observed in the castrated group, along with more apoptotic endothelial cells. Bcl-2 level was reduced and the expression of caspase-9, caspase-3 and Cyt C were elevated in the castrated group (p<0.05). But there was no significant difference between the replacement group and the control group (p>0.05). It was concluded that low androgen caused vascular endothelial damage. It may be, at least in part, related with the activating mitochondrial apoptotic pathways.

Window into the complexities of chromosome interactomes

DNA is folded into increasingly complex yet highly mobile structures to organize the chromosomes. In the interphase nucleus, chromosomes or part of the chromosomes encounter one another preferentially at the boundaries between chromosomal territories. Although this situation implies that the preferred chromosomal neighborhood is a key determinant of interactions between chromosomes, what this means in functional terms is currently not well understood. Using the H19 imprinting control region as a window, it has been demonstrated that epigenetic information of the primary chromatin fiber has dual functions. Thus, epigenetic marks not only influence the proximity between chromatin fibers but also transfer epigenetic states between chromatin fibers both in cis and in trans. High-throughput sequence and DNA fluorescence it situ hybridization (FISH) analyses reveal that these features require chromatin movements that are restricted in space and time. The mechanisms involved in the establishment of chromosome interactomes may provide insight of fundamental importance into pivotal regulatory processes in the nucleus, such as the coordination of transcriptional programs and replication timing.