Tsu-Yao Cheng

H3K9 histone methyltransferase G9a promotes lung cancer invasion and metastasis by silencing the cell adhesion molecule Ep-CAM

G9a is a mammalian histone methyltransferase that contributes to the epigenetic silencing of tumor suppressor genes. Emerging evidence suggests that G9a is required to maintain the malignant phenotype, but the role of G9a function in mediating tumor metastasis has not been explored. Here, we show that G9a is expressed in aggressive lung cancer cells, and its elevated expression correlates with poor prognosis. RNAi-mediated knockdown of G9a in highly invasive lung cancer cells inhibited cell migration and invasion in vitro and metastasis in vivo. Conversely, ectopic G9a expression in weakly invasive lung cancer cells increased motility and metastasis. Mechanistic investigations suggested that repression of the cell adhesion molecule Ep-CAM mediated the effects of G9a. First, RNAi-mediated knockdown of Ep-CAM partially relieved metastasis suppression imposed by G9a suppression. Second, an inverse correlation between G9a and Ep-CAM expression existed in primary lung cancer. Third, Ep-CAM repression was associated with promoter methylation and an enrichment for dimethylated histone H3K9. G9a knockdown reduced the levels of H3K9 dimethylation and decreased the recruitment of the transcriptional cofactors HP1, DNMT1, and HDAC1 to the Ep-CAM promoter. Our findings establish a functional contribution of G9a overexpression with concomitant dysregulation of epigenetic pathways in lung cancer progression.

Levofloxacin-based and clarithromycin-based triple therapies as first-line and second-line treatments for Helicobacter pylori infection: a randomised comparative trial with crossover design

Background The efficacy of a levofloxacin-based regimen as the first-line treatment and a clarithromycin-based regimen as the second-line treatment for Helicobacter pylori infection remains unknown. The aim of this study was to assess the eradication rates of these two regimens using different administration sequences. Methods Eligible patients were randomised to receive LAL: levofloxacin (750 mg once a day), amoxicillin (1000 mg twice a day) and lansoprazole (30 mg twice a day) for 7 days, or CAL: clarithromycin (500 mg twice a day), amoxicillin (1000 mg twice a day) and lansoprazole (30 mg twice a day) for 7 days. Patients with positive [13C]urea breath test after treatment were retreated with the rescue regimen in a crossover manner for 10 days. Result When used as first-line treatment (n=432), the eradication rates of LAL (n=217) and CAL (n=215) were 74.2 and 83.7% (p=0.015) in the intent-to-treat (ITT) analysis, and 80.1 and 87.4% (p=0.046) in the per-protocol (PP) analysis, respectively. When used as second-line treatment, the eradication rates of LAL (n=26) and CAL (n=40) were 76.9 and 60% (p=0.154) in the ITT analysis, and 80 and 61.5% (p=0.120) in the PP analysis, respectively. The overall eradication rates of CAL followed by LAL were better than the reverse sequence in both the ITT analysis (93% vs 85.3%, p=0.01) and the PP analysis (97.6% vs 92.5%, p=0.019). The eradication rate was significantly lower in the presence of levofloxacin resistance in the LAL group (50% vs 84.4%, p=0.018) and clarithromycin resistance in the CAL group (44.4% vs 90.7%, p=0.002). Conclusion CAL achieved a higher eradication rate than LAL as the first-line treatment, but not as the second-line treatment. The strategy of using CAL as the initial treatment and LAL as the rescue regimen achieved higher eradication rates than the reverse sequence. Clinical trial number NCT00816140.

Association of T-Cell Regulatory Gene Polymorphisms With Susceptibility to Gastric Mucosa-Associated Lymphoid Tissue Lymphoma

PURPOSE Helicobacter pylori infection and host susceptibility interact to develop gastric mucosa-associated lymphoid tissue (MALT) lymphoma, and activation of specific T cells might play a crucial role in this process. Recent investigations show that the CTLA4, CD28, and ICOS genes are located on chromosome 2q33 and their polymorphisms confer susceptibility to infectious and immune diseases through deregulation of T-cell stimulation. We aimed to determine the role of CTLA4, CD28, and ICOS polymorphisms in gastric MALT lymphoma. PATIENTS AND METHODS Genotyping for CTLA4 (49 A/G, -318 C/T, and CT60 A/G), CD28 (IVS3+ 17T/C), and ICOS (c.602 A/C and c.1624C/T) was performed for 62 patients with gastric MALT lymphoma and compared with 250 unrelated healthy controls. RESULTS H pylori infection was significantly higher in patients with gastric MALT lymphoma (90.3%) compared with controls (66.4%; P < .001). The CTLA4 -318 C/T genotype was associated with a lower risk of developing gastric MALT lymphoma (odds ratio [OR] = 0.3; P = .022), whereas CTLA4 49 G/G genotype was linked to a higher risk (OR = 4.1; P = .044). In patients with H pylori infection, CTLA4 49 G/G genotype was associated with an even higher risk (OR = 6.4; P = .047). Carriage of the tightly linked -318C -49G haplotype conferred a four-fold higher susceptibility to MALT lymphoma (OR = 4.2; P = .042). Complete remission after H pylori eradication was related to tumor stage but not to genotypes or haplotypes. CONCLUSION These results indicate a genetic link of CTLA4 gene polymorphisms to development of gastric MALT lymphoma and indirectly support the crucial role of host activated T cells in the MALT lymphomagenesis.

N-α-Acetyltransferase 10 Protein Suppresses Cancer Cell Metastasis by Binding PIX Proteins and Inhibiting Cdc42/Rac1 Activity

N-α-acetyltransferase 10 protein, Naa10p, is an N-acetyltransferase known to be involved in cell cycle control. We found that Naa10p was expressed lower in varieties of malignancies with lymph node metastasis compared with non-lymph node metastasis. Higher Naa10p expression correlates the survival of lung cancer patients. Naa10p significantly suppressed migration, tumor growth, and metastasis independent of its enzymatic activity. Instead, Naa10p binds to the GIT-binding domain of PIX, thereby preventing the formation of the GIT-PIX-Paxillin complex, resulting in reduced intrinsic Cdc42/Rac1 activity and decreased cell migration. Forced expression of PIX in Naa10-transfected tumor cells restored the migration and metastasis ability. We suggest that Naa10p functions as a tumor metastasis suppressor by disrupting the migratory complex, PIX-GIT- Paxillin, in cancer cells.

Annexin A1 is associated with gastric cancer survival and promotes gastric cancer cell invasiveness through the formyl peptide receptor/extracellular signal‐regulated kinase/integrin beta‐1‐binding protein 1 pathway

Annexin A1 (AnxA1) has been well‐known as a glucocorticoid‐regulated anti‐inflammatory protein, and it is implicated in tumorigenesis in a tumor type–specific pattern. However, the role of AnxA1 in gastric cancer (GC) is indeterminate, and the underlying mechanism is not clear. The purpose of this study was to evaluate the prognostic significance and associated mechanism of AnxA1 in GC.

Analysis of fine-needle aspiration cytology of the salivary gland.

BACKGROUND/PURPOSE Fine needle aspiration (FNA) cytology has been widely accepted as a safe method for diagnosis of salivary gland lesions. This study investigated the accuracy of FNA cytology of salivary gland lesions by correlation between histology and cytology. METHODS One hundred and thirty-one archived salivary gland FNA specimens collected between January 1994 and December 2002 from 131 patients were correlated with histopathology findings. The major reasons for false-negative and false-positive results in cytologic diagnosis were determined. RESULTS Considering the results of histopathology as the diagnostic standard, the sensitivity of FNA cytology in diagnosing malignancy was 74% (17/23) after excluding two cases which had a cytodiagnosis of suspicion of malignancy. Excluding eight cases that had a cytodiagnosis of suspicion of malignancy, the diagnostic specificity was 99% (97/98). There were six false-negative and one false-positive cases. CONCLUSION This study demonstrated that FNA cytology of the salivary gland is a useful technique for diagnosis of salivary gland lesions. Inadequate labeling of the aspiration sites and insufficient cellularity were the most important factors that resulted in incorrect cytologic interpretation.

Keap1-Nrf2 Interaction Suppresses Cell Motility in Lung Adenocarcinomas by Targeting the S100P Protein.

Purpose: Kelch-like ECH-associated protein 1 (Keap1) is an E3 ligase participated in the cellular defense response against oxidative stress through nuclear factor erythroid-2–related factor 2 (Nrf2). However, the role of Keap1 in regulating cancer motility is still controversial. We investigated the contribution of the Keap1–Nrf2 axis in the progression of non–small cell lung cancer (NSCLC). Experimental Design: The expression of Keap1 and Nrf2 was examined via immunohistochemistry, real-time PCR, and Western blot analysis in a cohort of NSCLC tissues and cells. A series of in vivo and in vitro assays was performed to elucidate the contribution of the Keap1–Nrf2 axis in lung cancer mobility and progression. Results: Keap1 expression was decreased in specimens from NSCLC patients with lymph node metastasis compared with patients without metastasis. Higher Keap1 expression levels were correlated with the survival of NSCLC patients. Moreover, manipulation of Keap1 expression affected cell migration/invasion abilities. Depletion of Nrf2 relieved the migration promotion imposed by Keap1 suppression. Mechanistic investigations found that S100P was downregulated in both Keap1-overexpressing and Nrf2-knockdown NSCLC cells. Overexpression of Keap1 and knockdown of Nrf2 both suppressed S100P expression in NSCLC cells. Knockdown of S100P inhibited cell migration in highly invasive NSCLC cells and also relieved the migration promotion imposed by Keap1 suppression in weakly invasive NSCLC cells. Conclusions: Our findings suggest that Keap1 functions as a suppressor of tumor metastasis by targeting the Nrf2/S100P pathway in NSCLC cells. In addition, overexpression of Keap1 may be a novel NSCLC treatment strategy and/or useful biomarker for predicting NSCLC progression. Clin Cancer Res; 21(20); 4719–32. ©2015 AACR.

Cytosolic PKM2 stabilizes mutant EGFR protein expression through regulating HSP90-EGFR association.

Secondary mutation of epidermal growth factor receptor (EGFR) resulting in drug resistance is one of the most critical issues in lung cancer therapy. Several drugs are being developed to overcome EGFR tyrosine kinase inhibitor (TKI) resistance. Here, we report that pyruvate kinase M2 (PKM2) stabilized mutant EGFR protein by direct interaction and sustained cell survival signaling in lung cancer cells. PKM2 silencing resulted in markedly reduced mutant EGFR expression in TKI-sensitive or -resistant human lung cancer cells, and in inhibition of tumor growth in their xenografts, concomitant with downregulation of EGFR-related signaling. Mechanistically, PKM2 directly interacted with mutant EGFR and heat-shock protein 90 (HSP90), and thus stabilized EGFR by maintaining its binding with HSP90 and co-chaperones. Stabilization of EGFR relied on dimeric PKM2, and the protein half-life of mutant EGFR decreased when PKM2 was forced into its tetramer form. Clinical levels of PKM2 positively correlated with mutant EGFR expression and with patient outcome. These results reveal a previously undescribed non-glycolysis function of PKM2 in the cytoplasm, which contribute to EGFR-dependent tumorigenesis and provide a novel strategy to overcome drug resistance to EGFR TKIs.

Cyr61/CTGF/Nov family proteins in gastric carcinogenesis

Gastric cancer (GC) is the second leading cause of cancer-related death. The poor survival rate may reflect the relatively aggressive tumor biology of GC. Recently, the importance of the tumor microenvironment in carcinogenesis has emerged. In the tumor microenvironment, tumor cells and the surrounding stromal cells aberrantly secrete matricellular proteins capable of modulating carcinogenesis and regulating metastasis. The Cyr61/CTGF/Nov (CCN) proteins are a family of matricellular proteins with variable roles in many physiological and pathological processes. The evidence suggests that CCN family proteins contribute to GC carcinogenic processes. Here, we briefly review recent research on the effects of CCN family proteins in GC carcinogenesis and the development of new targeted agents in this field.

Gastrointestinal: Burkitt's lymphoma

Lymphomas are solid malignancies of lymphoid tissue that can be categorized as either Hodgkin’s disease or nonHodgkin’s lymphoma. It is rare for Hodgkin’s disease to involve the gastrointestinal tract. Although the majority of non-Hodgkin’s lymphomas are thought to arise from lymph nodes, at least 30% arise in other organs and are called extranodal or primary lymphomas. Of these extranodal lymphomas, up to 40% are located in the gastrointestinal tract, particularly in the stomach and small bowel. Most of these lymphomas are of B-cell lineage. The most common are the diffuse large cell lymphoma and the marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma). Other B-cell lymphomas include Burkitt’s lymphoma, mantle cell lymphoma and follicular lymphoma. The images shown below were from a 76-year-old man who was admitted to hospital with malaise, weight loss and pain in the left flank. He subsequently had two significant episodes of hematemesis and melena. Upper gastrointestinal endoscopy revealed bleeding from multiple doughnut-like tumors in the body and antrum of the stomach (Fig. 1). He also had giant gastric folds. A computed tomography scan of the abdomen showed thickening of the wall of the jejunum and tumor infiltration of the left renal pelvis and parts of the right kidney. Histopathological examination of gastric biopsy specimens showed sheets of intermediate-sized lymphoid cells crowding between glands with an interspersed starry-sky pattern (Fig. 2; HE: ×200). Immunohistochemical stains were positive for CD20 (indicating B-cell lineage) and almost all cells were positive for Ki-67 (indicating an extremely high proliferation rate). The diagnosis was that of Burkitt’s lymphoma. Apart from Burkitt’s lymphoma, multiple gastric polypoid lesions with central ulceration can be seen in Kaposi’s sarcoma, stromal cell tumors, metastatic gastric tumors and other lymphomas. Although only 1‐2% of adult non-Hodgkin’s lymphoma are of the Burkitt’s variety, substantially higher percentages have been described in the pediatric setting and in patients with HIV. Blackwell Science, LtdOxford, UKJGHJournal of Gastroenterology and Hepatology0815-93192005 Blackwell Publishing Asia Pty LtdOctober 2005201016161616Images of Interest Images of InterestImages of Interest