Molecular characteristics of Asian male BRCA-related cancers

PURPOSE

Germline mutations of BRCA1 or BRCA2 predispose men to develop various cancers, including breast cancers and prostate cancers. Male breast cancer (MBC) is a rare disease while prostate cancer (PRC) is uncommon in young men at the age of less than 40. The prevalence of BRCA genes in Asian male patients has to be elevated.

METHODS

Germline mutations screening was performed in 98 high-risk Chinese MBC and PRC patients.

RESULT

We have identified 16 pathogenic BRCA2 mutation carriers, 12 were MBC patients, 2 were PRC patients and 2 were patients with both MBC and PRC. The mutation percentages were 18.8%, 6.7% and 50% for MBC, PRC and both MBC and PRC patients, respectively. BRCA2 gene mutations confer a significantly higher risk of breast/prostate cancers in men than those with BRCA1 mutations. BRCA mutated MBC patients had a younger age of diagnosis and strong family histories of breast cancers while BRCA mutated PRC patients had strong family histories of ovarian cancers.

CONCLUSION

Male BRCA carriers with breast cancers or prostate cancers showed distinct clinical and molecular characteristics, a male-specific genetic screening model would be useful to identify male cancer patients who have a high risk of BRCA mutation.

Inhibition of EP2 receptor suppresses tumor growth and chemoresistance of gastric cancer

Gastric cancer is one of the leading causes of cancer death in the world. Early diagnosis and effective chemotherapy are vital to reduce the overall mortality. Prostaglandin E2 (PGE2) has been implicated as an important factor in gastric cancer carcinogenesis. ECF based regimen (epirubicin, cisplatin, 5-fluorouracil) is the first-line chemotherapy for advanced gastric cancer. However, patients develop resistance after chemotherapy. The aim of this study is sought to investigate the role of EP2 receptor, a PGE₂ receptor, and the antagonism of EP2 receptor in response to ECF treatment. Expression of EP2 receptor was evaluated in gastric cancer tissue samples and cell lines. Cell proliferation and cell apoptosis assays were performed in vitro and in vivo, upon knockdown of EP2 receptor, antagonist of EP2 receptor and/or ECF treatment. Western Blot was applied for evaluation of proteins relating to cell cycle, apoptosis and drug transporter. Next generation sequencing and ingenuity pathway analysis were applied for screening for downstream targets of EP2 receptor. Expressions of the targets of EP2 receptor were further evaluated in gastric cancer cells and tissues. In this study, we found that expression of EP2 receptor was significantly upregulated in gastric cancer. Inhibition of EP2 receptor reduced gastric cancer cell proliferation, induced cell cycle arrest proteins, and enhanced cell apoptosis. Moreover, knockdown of EP2 receptor by siRNA or antagonist sensitized gastric cancer cells to ECF. Silence of EP2 receptor also significantly abrogated gastric cancer growth in a mice model. Analysis revealed that CAV1 was a downstream target of EP2 receptor in gastric cancer. Our findings illustrated that blocking EP2 receptor reduced tumor growth and induced apoptosis in gastric cancer. This novel study unraveled CAV1 was a downstream target of EP2 receptor. Antagonizing EP2 receptor could be a potential therapeutic target in gastric cancer, in particular those with high EP2 receptor expression.

How does re-classification of variants of unknown significance (VUS) impact the management of patients at risk for hereditary breast cancer?

Background

The popularity of multigene testing increases the probability of identifying variants of uncertain significance (VUS). While accurate variant interpretation enables clinicians to be better informed of the genetic risk of their patients, currently, there is a lack of consensus management guidelines for clinicians on VUS.

Methods

Among the BRCA1 and BRCA2 mutations screening in 3,544 subjects, 236 unique variants (BRCA1: 86; BRCA2: 150) identified in 459 patients were being reviewed. These variants consist of 231 VUS and 5 likely benign variants at the initial classification.

Results

The variants in 31.8% (146/459) patients were reclassified during the review, which involved 26 unique variants (11.0%). Also, 31 probands (6.8%) and their family members were offered high-risk surveillance and related management after these variants were reclassified to pathogenic or likely pathogenic. At the same time, 69 probands (15%) had their VUS downgraded to cancer risk equivalent to the general population level.

Conclusion

A review of archival variants from BRCA1 and BRCA2 genetic testing changed the management for 31.8% of the families due to increased or reduced risk. We encourage regular updates of variant databases, reference to normal population and collaboration between research laboratories on functional studies to define the clinical significances of VUS better.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01270-4.

Germline mutations in Chinese ovarian cancer with or without breast cancer

BACKGROUND

Ovarian and breast cancers are known to have significant genetic components. Considering the differences in the mutation spectrum across ethnicity, it is important to identify hereditary breast and ovarian cancer (HBOC) genes mutation in Chinese for clinical management.

METHODS

Two cohorts of 451 patients with ovarian cancer only (OV) and 93 patients with both breast and ovarian (BROV) cancers were initially screened for BRCA1, BRCA2, TP53, and PTEN. 109 OV and 43 BROV patients with extensive clinical risk and were being tested negative, were then further characterized by 30-gene panel analysis.

RESULTS

Pathogenic BRCA1/2 variants were identified in 45 OV patients and 33 BROV patients, giving a prevalence of 10% and 35.5%, respectively. After the extended screening, mutations in other HBOC genes were identified in an additional 12.8% (14/109) of the OV cohort and 14% (6/43) in the BROV cohort. The most commonly mutated genes in the OV cohort were MSH2 (4.6%) while in the BROV cohort were MSH2 (4.7%) and PALB2 (4.7%). With this extended multigene testing strategy, pathogenic mutations were detected in 12.8% of OV patients (BRCAs: 10%; additional genes: 12.8%) and 40.9% (BRCAs: 35.5%; additional genes: 14%) of BROV patients.

CONCLUSION

Extended characterization of the contributions of HBOC genes to OV and BROV patients has significant impacts on further management in patients and their families, expanding the screening net for more asymptomatic individuals.

MicroRNA-199a-3p promotes drug sensitivity in triple negative breast cancer by down-regulation of BRCA1

MiR-199a-3p was previously predicted to target tumor suppressor gene BRCA1, which has been linked to cancer onset and therapeutic response. In this study, the effects of miR-199a-3p-mediated BRCA1 dysfunction on triple-negative breast cancer (TNBC) progression and chemosensitivity were assessed. The association between miR-199a-3p and BRCA1 expression was examined in TNBC tumors and verified with luciferase reporter and protein assays. Tumorigenic functions of miR-199a-3p in TNBC cells were investigated by cell proliferation, clonogenic and migration assays. The sensitivities to chemotherapeutic drugs were tested with cisplatin and PARP inhibitor (veliparib) treatments. Mouse xenograft model was used to examine the effects of miR-199a-3p on tumor growth and drug response in vivo. MiR-199a-3p was shown to directly target BRCA1 in TNBC cells, resulting its downregulation and reduced luciferase reporter activity mediated by BRCA1 3'-UTR. Ectopic miR-199a-3p in TNBC cells exerted inhibitory effects on cell proliferation, migration and xenograft tumor growth. Moreover, miR-199a-3p was shown to reverse cisplatin-resistance and sensitize TNBC cells to veliparib, which might be due to repressed DNA repair ability and induced cell apoptosis. Our results demonstrated the tumor suppressive effects of miR-199a-3p on TNBC and induction on chemotherapeutic sensitivities, which were correlated with BRCA1 gene dysfunction. These findings may provide insights into the potential prognostic and therapeutic values of miR-199a-3p in patients with TNBC.

Resveratrol enhanced chemosensitivity by reversing macrophage polarization in breast cancer

BACKGROUND

Resveratrol, a naturally occurring polyphenolic compound, has been shown to inhibit cancer growth by targeting several cancer-related signalling pathways. In the tumor microenvironment (TME), tumor-associated macrophages (TAMs) are the most abundant leukocyte population that are associated with poor prognosis in over 80% of breast cancer cases. However, little is known about the effect of resveratrol in the TME.

METHODS

In this study, MDA-MB-231(MB231), cisplatin resistance MDA-MB-231 (cisR), and T47D were used to examine the antitumor effect of resveratrol. The effectiveness of resveratrol, together with cisplatin as breast cancer treatment was investigated in vivo. Gene expressions of M1 (iNOS and CXCL10) and M2 (ARG1, CD163 and MRC1) markers in differentiated macrophages derived from THP-1 cells were examined to investigate the effect of resveratrol on TAM polarization in breast cancer progression.

RESULTS

Our results demonstrated that resveratrol significantly reduced cell proliferation and enhanced chemosensitivity in breast cancer cells by inhibiting production of IL-6 and STAT3 activation. Treatment of resveratrol increased CXCL10 (M1 marker) expression. Further, resveratrol decreased IL-6 levels in LPS-treated differentiated macrophages. The use of resveratrol with cisplatin inhibited suppressed tumor growth when compared with cisplatin alone.

CONCLUSION

This study revealed that resveratrol inhibited breast cancer cell proliferation by promoting M1/M2 macrophage polarization ratio and suppressing IL-6/pSTAT3 pathway.

Mutation screening of germline TP53 mutations in high-risk Chinese breast cancer patients

BACKGROUND

Germline TP53 mutations are associated with Li-Fraumeni syndrome, a severe and rare hereditary cancer syndrome. Despite the rarity of germline TP53 mutations, the clinical implication for mutation carriers and their families is significant. The risk management of TP53 germline mutation carriers is more stringent than BRCA carriers, and radiotherapy should be avoided when possible.

METHODS

TP53 gene mutation screening was performed in 2538 Chinese breast cancer patients who tested negative for BRCA mutations.

RESULTS

Twenty TP53 mutations were identified with high next-generation sequencing concerning for germline mutations in Chinese breast cancer families. The majorities of the TP53 carriers had early-onset, hormone receptor-positive breast cancer, and had strong family history of cancer. Among all, 11 patients carried a germline mutation and 6 of which were likely de novo germline mutations. In addition, 1 case was suspected to be induced by chemotherapy or radiation, as this patient had no significant family history of cancer and aberrant clonal expansion can commonly include TP53 mutations. Furthermore, we have identified one mosaic LFS case. Two novel mutations (c.524_547dup and c.529_546del) were identified in patients with early-onset.

CONCLUSIONS

In view of the high lifetime risk of malignancy, identification of patients with germline TP53 mutations are important for clinicians to aid in accurate risk assessment and offer surveillance for patients and their families.

Human haptoglobin contributes to breast cancer oncogenesis through glycolytic activity modulation

Cellular metabolism reprogramming is a hallmark in cancers including breast cancer. Switching off the glycolytic energy in cancer has been indicated as one of the anti-cancer strategies. Aberrant haptoglobin (HP) expression has been shown to cause metabolic dysfunction and implicated in different malignancies. However, its roles in breast cancer and glycolysis remain elusive. Here, we reported HP was upregulated in breast cancer tissues and the circulation. HP conferred oncogenic roles by regulating cell cycle progression and apoptosis in breast cancer cells. Further analysis identified the correlation between HP and glycolytic enzymes such as glucose-6-phosphate isomerase (GPI) and hexokinase (HK). Glycolytic activities were altered upon HP knockdown which were confirmed by glucose uptake and LDH activity assays. GPI was found to be downstream effector of HP while knockdown of GPI led to decreased glycolytic activity and restored oxygen consumption. GPI silencing decreased cell migration/invasion ability and sensitized breast cancer cells to chemo-drug. Moreover, animal study suggested inhibition of both HP and GPI significantly impeded tumor growth in mice. Collectively, we report for the first time the oncogenic roles of HP, at least partially, through regulating glycolysis and its downstream effector, GPI, contributes in maintaining EMT and chemoresistance in breast cancer.

Somatic mutation profiling in BRCA-negative breast and ovarian cancer patients by multigene panel sequencing

Targeted therapeutic agents such as poly (ADP-ribose) polymerases (PARP) inhibitors have emerged in treating cancers associated with germline BRCA mutations. Recently studies demonstrated the effectiveness of PARP inhibitors in treating patients with somatic BRCA mutations. Somatic mutations in 122 Chinese breast or ovarian cancer patients without BRCA, PTEN and TP53 mutations were screened using multigene sequencing panel. The five most frequent pathogenic or likely pathogenic mutated genes identified in breast cancer patients were PIK3CA (28.6%), TP53 (16.9%), MAP3K1 (14.3%), GATA3 (14.3%) and PTEN (5.2%). The five most frequently mutated genes identified in ovarian patients were TP53 (52.9%), KRAS (23.5%) and PIK3CA (11.8%), BRCA1 (5.9%) and RB1 (5.9%). Somatic PIK3CA and TP53 mutations were common events in both germline BRCA-negative breast and ovarian cancer patients. In contrast, somatic screening of BRCA mutations in BRCA-negative breast cancer patients has limited value. The results highlight the benefit of somatic testing to guide future research directions on other targeted therapies for breast and ovarian malignancies.

Functional Implications of Cathelicidin Antimicrobial Protein in Breast Cancer and Tumor-Associated Macrophage Microenvironment

It is well-established that tumor-associated macrophages (TAMs) play an important role in breast cancer development. Accumulating evidence suggested that human cathelicidin antimicrobial protein (CAMP), which is mainly expressed in host defense cells such as macrophages, is crucial not only in combating microorganisms but also promoting tumor growth. Here we report the interaction of CAMP with TAMs in breast cancer. CAMP expression was upregulated in cancer tissues and in the circulation of breast cancer patients. Surgical removal of tumor decreased CAMP peptide serum level. Knockdown of CAMP decreased cell proliferation and migration/invasion ability in breast cancer cells. CAMP expression was altered during macrophage M1/M2 polarization and was expressed predominantly in M2 phenotype. In addition, breast cancer cells co-cultured with macrophages upregulated CAMP expression and also increased cancer cell viability. Xenograft tumors reduced significantly upon CAMP receptor antagonist treatment. Our data implicated that CAMP confers an oncogenic role in breast cancer and plays an important role in the tumor microenvironment between TAMs and breast cancer cells, and blocking the interaction between them would provide a novel therapeutic option for this malignant disease.

Abstract P6-06-16: Resveratrol enhanced chemosensitivity by reversing macrophage polarization in breast cancer

Background: Resveratrol is a naturally occurring polyphenolic compound in Polygonum cuspidatum and is well known for its antitumor effect by targeting several cancer-related inflammatory pathways. However, limited data is available on the effect of resveratrol in the tumor microenvironment (TME). Tumor-associated macrophages (TAMs) are the most abundant leukocyte population within the tumors and are associated with poor prognosis in over 80% of breast cancer cases. This study aimed to investigate the effect of resveratrol on TAM polarization in breast cancer progression.

Methods: The antitumor effect of resveratrol was examined in MDA-MB-231(MB231), cisplatin resistance MDA-MB-231 (cisR) cells, and T47D by cell proliferation assay using MTT. Gene expressions of M1 and M2 markers in macrophages derived from THP-1 cells were examined by qPCR and immunofluorescence staining after treated with tumor-conditioned medium (TCM) with or without resveratrol (25μM). Cytokine profile of TCM was examined by Qiagen Multi-Analyte ELISArray and expression of cytokines in TCM was validated by qPCR and ELISA. The effect of resveratrol and its downstream targets on macrophage polarization were investigated by supplementing resveratrol with interferon gamma (IFN-γ, 20ng/ml) and lipopolysaccharide (LPS, 100ng/ml) for M1 macrophage polarization or IL-4 (20ng/ml) and IL-13 (20ng/ml)for M2 macrophage polarization. NOD/SCID mice were used to investigate the potential use of resveratrol in treating breast cancer and chemotherapy as complementary treatment in vivo.

Results: Our preliminary data demonstrated that resveratrol significantly reduced cell proliferation and enhanced chemosensitivity in MB231, cisR, and T47D cells. Resveratrol inhibited CD163 (M2 marker) and increased CXCL10 (M1 marker) expression. In addition, resveratrol decreased exogenous IL-6 levels in TCM, thus inhibited breast cancer cell proliferation by promoting M1/M2 macrophage polarization ratio and supressing IL-6/pSTAT3 pathway. Combined use of resveratrol and cisplatin significantly decreased tumor size in vivo.

Conclusion: Our data demonstrated that resveratrol enhanced chemosensitivity in vivo and in vitro by promoting M1/M2 macrophage polarization ratio and supressing STAT3 activation through reducing exogenous IL-6 levels. This study revealed a novel mechanism on resveratrol-mediated macrophage polarization on breast cancer progression.

Correspondence: akwong@asiabreastregistry.com

Citation Format: Isabella Wai Yin Cheuk, Jiawei Chen, Man Ting Siu, Sau Wing Lam, Jue Wang, Vivian Yvonne Shin, Ava Kwong. Resveratrol enhanced chemosensitivity by reversing macrophage polarization in breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-06-16.

ITGAV targeting as a therapeutic approach for treatment of metastatic breast cancer

During tumorigenesis and metastasis, integrins regulate localization and activity of proteolytic enzymes that remodel the extracellular matrix. Previous studies have demonstrated blocking of α_Vβ₃ to effectively inhibit proliferation, angiogenesis, and the survival of various cancer cell types. However, little is known about the functional role of the integrin subunit alpha-V gene (ITGAV) in metastatic breast cancer. In this study, ITGAV knockdown was used to identify the molecular mechanism by which ITGAV promotes tumorigenesis, metastasis, proliferation, invasion, and cellular self-renewal. The effectiveness of an ITGAV antagonist, cilengitide, for breast cancer treatment was investigated in vivo. Analysis of publicly available data demonstrated that overexpression of ITGAV was associated with poor relapse free survival of breast cancer patients. Silencing of ITGAV inhibited cell proliferation, invasion, and self-renewal of breast cancer cell lines by altering expression of BCL2 and PXN. The use of cilengitide significantly reduced lung metastasis in a metastatic breast cancer animal model. In conclusion, overexpression of ITGAV contributes to breast cancer metastasis through upregulation of PXN. Targeting ITGAV is a potential treatment for metastatic breast cancer as well as primary breast tumors with high ITGAV expression. ITGAV expression levels may be useful predictors of patient treatment and outcome responses.

Acetylcholine receptors: Key players in cancer development

Acetylcholine (ACh) was first identified as a classic neuromodulator and transmit signals through two subgroups of receptors, namely muscarinic receptors (mAChRs) and nicotinic receptors (nAChRs). Apart from its well-established physiological role in central nervous system (CNS) and peripheral nervous system (PNS), autonomic nervous system and neuromuscular junction, the widely distributed expression of AChRs in different human organs suggests roles in other biological processes in addition to synaptic transmission. Accumulating evidence revealed that cancer cell processes such as proliferation, apoptosis, angiogenesis and even epithelial-mesenchymal transition (EMT) are mediated by overexpression of AChRs in different kinds of tumors. In breast cancer, α7-nAChR and α9-nAChR were reported to be oncogenic. On the other hand, research on the role of mAChRs in breast cancer tumorgenesis is limited and confined to M3 receptor only. Since AChRs distributed in both CNS and PNS even non-neuronal tissues, there is an urgent need for the development of subtype-specific AChR antagonist which inhibits cancer cell progression with minimal intervention on the normal acetylcholine-regulated system within human body.

Methylated Septin 9 and Carcinoembryonic Antigen for Serological Diagnosis and Monitoring of Patients with Colorectal Cancer After Surgery

With the increasing incidence and mortality of colorectal cancer (CRC), early and accurate diagnosis is of paramount priority to combat this cancer. Epigenetic alterations such as DNA methylation are innovative biomarkers for CRC, due to their stability, frequency, and accessibility in bodily fluids. In this study, blood samples were prospectively collected from patients before and after operation for CRC for determination of methylated septin 9 (mSEPT9) and compared to carcinoembryonic antigen (CEA). The sensitivity of using mSEPT9 methylation status for diagnosing CRC was significantly higher than using elevated CEA levels (73.2% vs 48.2%; p value < 0.001). The sensitivities of both tests increased with higher tumor staging (P = 0.004 and 0.04 respectively). Combined mSEPT9 and CEA had higher accuracy than single CEA or mSEPT9 (P = 0.009 and 0.532 separately). An increase in the methylation level of mSEPT9 detected in the post-operative samples was associated with a higher mortality rate (15.2% vs 1.8%; P = 0.024) and the presence of metastasis (27.3% vs 7.0%; P = 0.013). mSEPT9 was more sensitive than CEA for diagnosing CRC, and combined mSEPT9 and CEA was more accurate. After curative resection, detection of increased mSEPT9 methylation level may indicate adverse outcomes.

Long non-coding RNA NEAT1 confers oncogenic role in triple-negative breast cancer through modulating chemoresistance and cancer stemness

Triple-negative breast cancer (TNBC) is a malignant subtype of breast cancer with the absence of targeted therapy, resulting in poor prognosis in patients. Chemotherapy remains the mainstay of treatment for TNBC; however, development of drug resistance is the main obstacle for successful treatments. In recent years, long non-coding RNA (lncRNA) has been implicated in multiple biological functions in various diseases, particularly cancers. Accumulating evidence suggested that lncRNA nuclear paraspeckle assembly transcript 1 (NEAT1) expression is dysregulated in many human cancers and thus is a useful prognostic marker for cancer patients. Nevertheless, the mechanism of how NEAT1 confers drug resistance in TNBC is still largely unknown. We performed lncRNA profiling by the LncRNA Profiler qPCR Array Kit in normal control (NC) and breast cancers (BC) blood samples and further validated in a larger cohort of samples by qRT-PCR. Gene expression level and localization were investigated by qRT-PCR, western blotting, and immunofluorescence staining. Flow cytometric analysis was carried out to detect cancer stem cells. Functional studies were performed both in vitro and in vivo xenograft model. Among 90 lncRNAs, NEAT1 was highly expressed in the blood samples of breast cancer patients than in NC. In particular, the expression of NEAT1 was higher in TNBC tissues than other subgroups. Functional studies revealed that NEAT1 conferred oncogenic role by regulating apoptosis and cell cycle progression in TNBC cells. We identified that knockdown of NEAT1 sensitized cells to chemotherapy, indicating the involvement in chemoresistance. Importantly, shNEAT1 reduced stem cell populations such as CD44+/CD24−, ALDH+, and SOX2+, implicating that NEAT1 was closely related to cancer stemness in TNBC. Our data highlighted the roles of NEAT1 chemoresistance and cancer stemness, suggesting that it could be used as a new clinical therapeutic target for treating TNBC patients especially those with drug resistance.

MiR-92 suppresses proliferation and induces apoptosis by targeting EP4/Notch1 axis in gastric cancer

MiR-92a has been shown to be dysregulated in various cancers and exhibited differential role in carcinogenesis. In this study, we sought to delineate the functional role of miR-92a and its regulatory pathway in gastric cancer. MiR-92a expression were underexpressed in tissues of gastric cancer patients with the area under curve (AUC) of 0.78. Low expression in plasma was due to the increased promoter DNA methylation of miR-92a. Overexpression of miR-92a inhibited cell proliferation and invasion, and induced apoptosis. Furthermore, miR-92a reduced tumor growth in xenograft model. EP4 and Notch 1 were identified to be negatively regulated by miR-92a, and involved in cell growth. Moreover, NF-κB expression was inversely correlated with miR-92a in gastric cancer tissues and suppressed the expression of miR-92. This study unravels the tumor suppressive role of miR-92a involving EP4/Notch 1 signaling regulated by NF-κB in gastric cancer. Further studies on miR-92a and EP4/Notch1 may provide a new treatment strategy for gastric cancer.

Detection of Methylated Circulating DNA as Noninvasive Biomarkers for Breast Cancer Diagnosis

Internationally, breast cancer is the most common female cancer, and is induced by a combination of environmental, genetic, and epigenetic risk factors. Despite the advancement of imaging techniques, invasive sampling of breast epithelial cells is the only definitive diagnostic procedure for patients with breast cancer. To date, molecular biomarkers with high sensitivity and specificity for the screening and early detection of breast cancer are lacking. Recent evidence suggests that the detection of methylated circulating cell-free DNA in the peripheral blood of patients with cancer may be a promising quantitative and noninvasive method for cancer diagnosis. Methylation detection based on a multi-gene panel, rather than on the methylation status of a single gene, may be used to increase the sensitivity and specificity of breast cancer screening. In this review, the results of 14 relevant studies, investigating the efficacy of cell-free DNA methylation screening for breast cancer diagnosis, have been summarized. The genetic risk factors for breast cancer, the methods used for breast cancer detection, and the techniques and limitations related to the detection of cell-free DNA methylation status, have also been reviewed and discussed. From this review, we conclude that the analysis of peripheral blood or other samples to detect differentially methylated cell-free DNA is a promising technique for use in clinical settings, and may improve the sensitivity of screening for both, early detection and disease relapse, and thus improve the future prognosis of patients with breast cancer.

Abstract P1-05-04: A novel mechanism of epithelial-mesenchymal transition in breast cancer metastasis: Involvement of prostanoid receptor

Background: Triple-negative breast cancer is associated with higher metastatic rate and poor prognosis than other subtypes of breast cancer due to lack of targeted therapy. Epithelial-mesenchymal transition (EMT) is linked with metastasis with phenotypic conversion of epithelial cells. However, the regulation of EMT in breast cancer metastasis remains largely unstudied. Recent attention has focused on targeting the downstream of COX-2 pathway, understanding the role of prostanoid receptors in breast cancer metastasis may help the development of effective therapeutic interventions for patients with metastasis.

Methods: A stable EP2-expression cell line (MB-231-EP2) was used to study tumorigenesis and distant metastasis in human breast cancer metastatic model. Localization of EP2 and EMT markers were examined by immunostaining and immunofluorescence. Profiles of drug transporters genes were compared between siEP2 and siControl cells. Functional role of EP2 on cell proliferation, invasion and apoptosis were assessed. Alteration of EMT markers were examined by real-time PCR and Western blot analysis.

Results: Expression of EP2 receptor were higher in human primary tumors than non-tumor tissues. EP2 receptor was predominantly expressed in metastatic tumors than primary tumors in human breast cancer metastatic mice model. The metastatic tumors showed a higher Ki67 (cell proliferation) and CD31 (angiogenesis) than primary tumors in the xenograft tissues. Larger tumors and poor survival were seen in MD-231-EP2 bearing mice when compared with control. Silencing of EP2 by siRNA markedly reduced cell proliferation and invasion, but increased apoptosis and expression of solute carrier family 19 member A3 (SLC19A3) gene. Interestingly, SLC19A3 had a lower expression in primary tumors and was inversely correlated with EP2 expression. Ectopic expression of SLC19A3 suppressed cell proliferation and invasion through the restoration of E-cadherin and other EMT markers (Twist, Zeb1 and Snai2). Immunofluorescence staining showed that the localization of Twist and E-cadherin were altered in siEP2 cells.

Conclusion: Our results showed that EP2 promoted EMT and breast cancer metastasis through the downregulation of SLC19A3 expression. Taken together, targeting EP2/SLC19A3 signaling pathway maybe a potential treatment for metastasis and adjuvant chemotherapy to reduce the metastatic risk.

Citation Format: Kwong A, Siu MT, Cheuk I, Ho JC, Chen J, Shin VY. A novel mechanism of epithelial-mesenchymal transition in breast cancer metastasis: Involvement of prostanoid receptor. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-05-04.

Abstract P2-09-20: Evaluation on the mutation screening by next-generation sequencing in hereditary breast and ovarian cancer: Implementation of recurrent mutation panel

Background: Hereditary disposition accounts for 10-15% in breast cancers and 20-25% in ovarian cancers, in which 5-10% of women have genomic alteration in breast cancer predisposition genes, BRCA1 and BRCA2, while the rest are likely due to less penetrant genes. In specific ethnicities such as Ashkenazi Jewish, three founder mutations have been identified which covers 95 % of all the BRCA mutations identified in this race. These genes are screened prior to the gold standard Sanger Sequencing in order to reduce cost. Sanger Sequencing, however, still has the limitation on the necessity of laborious processing and results interpretation. Moreover, it limits the number of genes that can be analyzed in one setting. With the use of next-generation sequencing (NGS), identification of hereditary breast and ovarian cancer (HBOC) syndrome associated genes, other than BRCA, can be sequenced at the same time but yet a faster turnover time. This allows more timely targeted risk-reducing strategies and interventions to be implemented for mutation positive carriers and their family members.

Methods: In this study cohort, 948 high-risk breast/ovarian patients who met the HBOC selection criteria were recruited for mutation screening by our NGS pipeline. With the inclusion of 90 Sanger-validated known mutation cases, the performance of the NGS pipeline were proven to be comparable to Sanger sequencing. PTEN and TP53, other than BRCA1 and BRCA2, a 4 gene sequencing panel were included in the mutation screening for high-risk patients.

Results: The prevalence of BRCA1/BRCA2 germline mutations was 7.28% in our Chinese cohort and 47.8% of the mutation were recurrent mutations. Based on this finding, we further adopted a new workflow by screening the recurrent mutations including founder mutations from Chinese cohort prior to NGS for those who tested negative. In a testing cohort of 343 cases, the recurrent mutation pick-up rate was 3.5%, this implicated a more cost-effective method for mutation screening in the clinical setting. Moreover, the frequencies of PTEN and TP53 were 0.21% and 0.53% respectively in our population with breast and ovarian cases.

Conclusion: Taken together, our data demonstrated a strategic upfront screening for recurrent mutations in Chinese population which is highly applicable in most of the diagnostic laboratories. Multi-gene sequencing using the NGS technology will be the upcoming strategies for mutation screening for HBOC patients.

Citation Format: Kwong A, Shin VY, Au CH, Law FB, Ho DN, Ip BK, Wong AT, Lau SS, To RM, Choy G, Ford JM, Ma ES, Chan TL. Evaluation on the mutation screening by next-generation sequencing in hereditary breast and ovarian cancer: Implementation of recurrent mutation panel. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-09-20.

A three-miRNA signature as promising non-invasive diagnostic marker for gastric cancer

Background

Despite the declining incidence of gastric cancer, mortality rate remains high due to late presentation. We aimed to evaluate the sensitivity of miRNA as a diagnostic marker for gastric cancer in the circulation.

Methods

Plasma samples from 3 independent groups comprise 123 gastric cancer patients and 111 healthy controls for miRNA profiling from microarray screening.

Results

Microarray data showed that 25 miRNAs were upregulated in gastric cancer patients and 6 highly expressed miRNAs (miR-18a, miR-140-5p, miR-199a-3p, miR-627, miR-629 and miR-652) were selected for validation. In an independent validation set, levels of miR-627, miR-629 and miR-652 were significantly higher in gastric cancer patients than healthy controls (P <0.0001). An algorithm with improved sensitivity and specificity as gastric cancer classifier was adopted and validated in another random set of 15 plasma samples. Results showed that combination of 3 miRNAs obtained the highest area under curve, with a cut-off at 0.373, with a sensitivity of 86.7 % and a specificity of 85.5 %.

Conclusion

This study revealed a three-miRNA signature as a promising classifier for gastric cancer, and greatly enhances the feasibility of circulating miRNAs as non-invasive diagnostic marker for this disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0473-3) contains supplementary material, which is available to authorized users.

Abstract 3105: MiR-199a-5p confers tumor suppressive role by inhibiting stenmness characteristics in triple-negative breast cancers

Objectives: Triple negative breast cancer (TNBC) is defined by lack of expression in estrogen (ER) and progesterone receptors (PR) as well as human epidermal growth factor receptor 2 (HER2), which accounts for 10-15% of all breast cancers. TNBC is a more aggressive histological subtype with worse prognosis when compared to other subtypes due to limited therapeutic targets for hormonal and HER2 receptors. With limited treatment options and ineffective targeted therapy, there is an urgent need for the development of novel therapeutic targets to treat this malignant form of breast cancer. Methods: Focused on the previously identified TNBC biomarker miR-199a-5p by our group, cells were transfected with 199a-5p mimic for functional studies. MTT and wound healing assay were performed to investigate the cell proliferation and migration ability. Immunofluorescence staining was introduced to study TWIST1 and E-cadherin expression in miR199a-5p stable transfected cells. Aldehyde dehydrogenase (ALDH) expression level was compared between breast cancers and normal control cases’ plasma by using real-time RT-PCR. We further used ALDH activity assay to evaluate the stem cell population. In vivo study was also carried out in nude mice to study tumorigenicity. Results: Cell proliferation assay showed that overexpression of miR-199a-5p significantly inhibited cell growth (p = 0.0008). Wound healing assay indicated the ectopic expression of miR-199a-5p can inhibit cell migration compared to control group. In miR-199a-5p stable transfected MDA-MB-231 cell line, increased translocation of Twist 1 protein from nucleus to cytoplasm and increased expression of E-cadherin was detected by immunofluorescence staining. ALDH activity assay result indicated that the proportion of ALDH(BR+) cells decreased significantly from 17.21% to 8.95% in the miR-199a-5p transfected cells when compared to the control group (p = 0.0279). Consistent with in vitro study, the well-recognized breast cancer stem-cell marker, ALDH1A, was significantly upregulated in the plasma of breast cancer patients than in healthy controls. Moreover, in vivo study also revealed that stable MDA-MB-231 cell line with ectopic miR199a-5p expression resulted in smaller volume of tumors in nude mice.

Conclusions: Our data implicate that miR-199a-5p plays a tumor suppressive role in the pathogenesis of TNBC, which may due to the inhibition of stemness characteristics in breast cancer cells. These findings suggest that miR-199a-5p involved in TNBC stemness-related features and thus provide insights in development of the novel therapeutic strategies for this highly malignant breast cancer.

Citation Format: Jiawei Chen, Man-Ting Siu, John Chi-Wang Ho, Vivian Yvonne Shin, Ava Kwong. MiR-199a-5p confers tumor suppressive role by inhibiting stenmness characteristics in triple-negative breast cancers. [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 3105. doi:10.1158/1538-7445.AM2015-3105

Circulating cell-free miRNAs as biomarker for triple-negative breast cancer

Background:

Triple-negative breast cancer (TNBC) accounts for 15–20% of all breast cancer in women globally. This subtype often has early and high recurrence rates resulting in poor survival, partially due to lack of targeted therapies. Therefore, there is an urgent need to identify TNBC-specific biomarkers for early diagnosis and treatment monitoring, and to develop more effective targeted therapy.

Methods:

By using miRCURY LNA array platform, we compared the differential miRNA expressions in plasma of patient with TNBC (n=5) and non-TNBC (n=5), as well as healthy controls (n=5). Potential miRNAs were then validated in a large cohort of patients by real-time PCR.

Results:

Ten putative miRNAs from the microarray data that differentially expressed between non-TNBC and healthy controls were identified. In the screening phase (n=90), we selected five miRNAs (miR-92a-3p, miR-342-3p, miR-16, miR-21 and miR-199a-5p) that could discriminate TNBC from non-TNBC for further validation. Results showed that miR-16, miR-21 and miR-199a-5p were underexpressed in TNBC when compared with non-TNBC, and were further validated in a large cohort (n=252). In addition, post-operative plasma levels of miR-16, miR-21 and miR-199a-5p were significantly restored when compared with pre-operative plasma of TNBC. Plasma miR-199a-5p expression in TNBC had significant difference when compared with non-TNBC and healthy controls, the receiver-operator characteristics curve analysis revealed the highest area under curve (AUC=0.8838) among all. The expression levels were associated with TNM stage and tumour subtypes.

Conclusions:

Our data suggest that miR-199a-5p could be a TNBC-specific marker with diagnostic value and provide insights into targeted therapy in the treatment of TNBC.

MiRNA as potential biomarkers and therapeutic targets for gastric cancer

Gastric cancer is one of the leading causes of cancer mortality in the world. Aberrant expression of microRNAs (miRNAs) is the hallmark of this disease. MiRNAs are endogenous non-coding RNAs that are involved in many biological processes (e.g., cell proliferation, differentiation, apoptosis, invasion and development) through gene repression. Deregulation of miRNA expression in gastric tumors and cancer cell lines have been documented to contribute in tumorigenesis, and the expression signature may correlate with different cancer types and clinicopathological features. Here, we summarized the updated gastric cancer-associated miRNAs and the downstream targets in the process of tumorigenesis. Recently, many researchers make use of the miRNA microarray platform to profile miRNA expression in gastric cancer and correlated with different clinical parameters. Its application on cancer diagnosis, prognosis and predicting treatment response rate are still underway and needs further investigation. Emerging roles of miRNAs with oncogenic or tumor suppressive properties in gastric tumorigenesis were discussed. Epigenetic silencing of miRNA by hypermethylation of promoter CpG island was also observed in gastric cancer. However, detailed mechanisms of how miRNAs regulate gene expression in gastric cancer has not been well studied. In this review, we highlight the up-to-date findings on the deregulated miRNAs in gastric cancer, and the potential use of miRNA in the clinical settings, such as diagnostic/prognostic markers and chemotherapeutic tools.

Abstract P2-07-03: High-throughput germline mutation screening for hereditary breast cancer in southern Chinese patients by massively parallel DNA sequencing

Introduction: Breast cancer is the most common malignancy and 3rd leading cause of deaths among the female population in Hong Kong. Since the establishment of The Hong Kong Hereditary Breast Cancer Family Registry in 2007, 1344 patients with breast and/or ovarian cancer who met the selection criteria were recruited for genetic testing in Hong Kong. Since 2011 we started to employ next-generation DNA sequencing (NGS) to expedite the analysis workflow and expand the panel of genes for sequencing.

Aim: To evaluate the workflow of NGS in mutation screening of BRCA1, BRCA2, TP53 and PTEN genes, and compared with the sequence data obtained by Sanger sequencing.

Methods: We sequenced BRCA1, BRCA2, TP53 and PTEN genes in peripheral blood samples of 410 patients, 53 positive controls and 107 healthy local individuals using 454 GS Junior System. Generation of barcoded amplicon libraries was streamlined by microfluidic PCR using Fluidigm Access Array System. Sequencing data were analyzed by an in-house developed fully automatic bioinformatics pipeline, which mainly consists of GS Amplicon Variant Analyzer, SAMtools and Ensembl Variant Effect Predictor. All putative mutations identified were validated by Sanger sequencing. Furthermore, the frequency of BRCA1, BRCA2 and PTEN missense variants of unknown significance (VUS) identified in the cohort were compared among 107 healthy local individuals and 1000 Genomes project samples. The VUS were also subjected to a panel of in silico prediction methods including PolyPhen and SIFT.

Results: Among 410 patients, there were 7 in BRCA1, 6 in BRCA2 and 1 in TP53 mutations found, including 1 novel recurrent BRCA2 (c.7007G&gt;T) and 1 novel founder BRCA2 (c.5164_5165delAG) mutations. Based on multiple criteria, 12 in BRCA1, 12 in BRCA2 and 1 in PTEN VUS could be prioritized for further investigation. The bioinformatics pipeline was extensively evaluated with Sanger-validated controls. The evaluation determined minimum sequencing coverage needed in this sequencing platform for accurate analysis. The pipeline accuracy was demonstrated by successful detecting mutations from 53 positive controls, including single nucleotide variants, insertions and deletions in different sequence context.

Conclusion: BRCA1, BRCA2, TP53 and PTEN mutation screening of 410 patients were expedited by high-throughput DNA sequencing. This method could detect 14 positive cases, including recurrent mutations, in a shorter period of time when compared with Sanger full gene sequencing. High-risk patients who are negative for the gene panel may need further investigation other than screening for BRCA1/2. The in-house developed bioinformatics pipeline was validated to detect various types of mutations and potentially become a conventional platform for genetic screening.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-07-03.

Abstract P3-01-02: Quantitative Analysis and Diagnostic Significance of Methylated SLC19A3 DNA in the Plasma of Breast Cancer Patients

Background: Previously, we have examined the methylation status of SLC19A3 (solute carrier family 19, member 3) promoter and found that SLC19A3 was epigenetically down-regulated in gastric cancer. Here, we aim to develop a new biomarker for cancer diagnosis using methylated SLC19A3 DNA in plasma.

Methods: SLC19A3 gene expression was examined by RT-qPCR. Methylation status of SLC19A3 promoter was evaluated by methylation-specific qPCR. A robust and simple methylation-sensitive restriction enzyme digestion and real-time quantitative PCR assay was developed to quantify SLC19A3 DNA methylation in plasma. Results: Expression of SLC19A3 was significantly down-regulated in 80% (12/15) of breast tumors (P &lt; 0.005). Breast tumors had significant increase in methylation percentage when compared to adjacent non-tumor tissues (P &lt; 0.05). A total of 155 independent plasma samples from participants including 60 breast cancer, 45 gastric cancer patients and 60 healthy subjects were analyzed. Plasma methylated SLC19A3 DNA yielded a ROC curve area of 77%, sensitivity of 82% and specificity of 60% in discriminating breast cancer from control subjects. This marker yielded a ROC curve area of 87%, sensitivity of 90.0% and specificity of 62% in discriminating gastric cancer from control subjects. Elevated level in plasma has been detected not only in advanced stages but also early stages of tumors. Intriguingly, of all DCIS cases from breast cancer patients this plasma marker generated a ROC value of 92%, sensitivity of 100% and specificity of 78% in discriminating DCIS cases from controls. Conclusions: These results suggested that aberrant SLC19A3 promoter hypermethylation in plasma may be a novel biomarker for early breast cancer diagnosis.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-01-02.

Effects of cigarette smoking and restraint stress on human colon tumor growth in mice

BACKGROUND

Cigarette smoking is a risk factor for colon cancer. Studies suggest that stress increases the incidence and promotes the development of cancers. Cigarette smoking and stress are closely associated, as people often smoke under stressful conditions and both of them can activate the adrenergic nervous system.

AIMS

To investigate the effects of cigarette smoking and restraint stress on colon cancer growth and the possible underlying mechanisms in these pathological processes.

METHODS

Nude mice bearing a HT-29 human colon cancer xenograft were either exposed to cigarette smoke and/or restraint stress. Cotinine and epinephrine levels in plasma of nude mice were measured by enzyme immunoassays. Expression of cyclooxygenase-2 (COX-2) and B-cell lymphoma-2 (Bcl-2) in tumor tissues were detected by Western blot. Prostaglandin E(2) (PGE(2)) concentrations were determined by enzyme immunoassay.

RESULTS

4% cigarette smoking together with restraint stress 1 h daily for 33 days promoted tumor growth in nude mice. This was accompanied by the increase of plasma levels of cotinine and epinephrine in these animals. They also enhanced the COX-2, Bcl-2 expressions and PGE(2) levels in tumor tissues.

CONCLUSION

These findings are important in understanding the pathogenesis of colon cancer, particularly related to cigarette smoking and stress.

Warburg effect revisited: an epigenetic link between glycolysis and gastric carcinogenesis

In cancer cells, glucose is often converted into lactic acid, which is known as the 'Warburg effect'. The reason that cancer cells have a higher rate of aerobic glycolysis, but not oxidative phosphorylation, remains largely unclear. Herein, we proposed an epigenetic mechanism of the Warburg effect. Fructose-1,6-bisphosphatase-1 (FBP1), which functions to antagonize glycolysis was downregulated through NF-kappaB pathway in Ras-transformed NIH3T3 cells. Restoration of FBP1 expression suppressed anchorage-independent growth, indicating the relevance of FBP1 downregulation in carcinogenesis. Indeed, FBP1 was downregulated in gastric carcinomas (P<0.01, n=22) and gastric cancer cell lines (57%, 4/7). Restoration of FBP1 expression reduced growth and glycolysis in gastric cancer cells. Moreover, FBP1 downregulation was reversed by pharmacological demethylation. Its promoter was hypermethylated in gastric cancer cell lines (57%, 4/7) and gastric carcinomas (33%, 33/101). Inhibition of NF-kappaB restored FBP1 expression, partially through demethylation of FBP1 promoter. Notably, Cox regression analysis revealed FBP1 promoter methylation as an independent prognosis predicator for gastric cancer (hazard ratio: 3.60, P=0.010). In summary, we found that NF-kappaB functions downstream of Ras to promote epigenetic downregulation of FBP1. Promoter methylation of FBP1 can be used as a new biomarker for prognosis prediction of gastric cancer. Such an important epigenetic link between glycolysis and carcinogenesis partly explains the Warburg effect.

Differential expression of microRNAs in plasma of patients with colorectal cancer: a potential marker for colorectal cancer screening

OBJECTIVE

MicroRNAs (miRNAs) have been shown to offer great potential in the diagnosis of cancer. We investigated whether plasma miRNAs could discriminate between patients with and without colorectal cancer (CRC).

METHODS

This study was divided into three phases: (1) marker discovery using real-time PCR-based miRNA profiling on plasma, corresponding cancerous and adjacent non-cancerous colonic tissues of five patients with CRC, along with plasma from five healthy individuals as controls; (2) marker selection and validation by real-time quantitative RT-PCR on a small set of plasma; and (3) independent validation on a large set of plasma from 90 patients with CRC, 20 patients with gastric cancer, 20 patients with inflammatory bowel disease (IBD) and 50 healthy controls.

RESULTS

Of the panel of 95 miRNAs analysed, five were upregulated both in plasma and tissue samples. All the five miRNAs were validated on the plasma of 25 patients with CRC and 20 healthy controls. Both miR-17-3p and miR-92 were significantly elevated in the patients with CRC (p<0.0005). The plasma levels of these markers were significantly reduced after surgery in 10 patients with CRC (p<0.05). Further validation with an independent set of plasma samples (n = 180) indicated that miR-92 differentiates CRC from gastric cancer, IBD and normal subjects. This marker yielded a receiver operating characteristic curve area of 88.5%. At a cut-off of 240 (relative expression in comparison to RNU6B snRNA), the sensitivity was 89% and the specificity was 70% in discriminating CRC from control subjects.

CONCLUSION

MiR-92 is significantly elevated in plasma of patients with CRC and can be a potential non-invasive molecular marker for CRC screening.

Differential expression of microRNAs in plasma of patients with colorectal cancer: a potential marker for colorectal cancer screening

OBJECTIVE

MicroRNAs (miRNAs) have been shown to offer great potential in the diagnosis of cancer. We investigated whether plasma miRNAs could discriminate between patients with and without colorectal cancer (CRC).

METHODS

This study was divided into three phases: (1) marker discovery using real-time PCR-based miRNA profiling on plasma, corresponding cancerous and adjacent non-cancerous colonic tissues of five patients with CRC, along with plasma from five healthy individuals as controls; (2) marker selection and validation by real-time quantitative RT-PCR on a small set of plasma; and (3) independent validation on a large set of plasma from 90 patients with CRC, 20 patients with gastric cancer, 20 patients with inflammatory bowel disease (IBD) and 50 healthy controls.

RESULTS

Of the panel of 95 miRNAs analysed, five were upregulated both in plasma and tissue samples. All the five miRNAs were validated on the plasma of 25 patients with CRC and 20 healthy controls. Both miR-17-3p and miR-92 were significantly elevated in the patients with CRC (p<0.0005). The plasma levels of these markers were significantly reduced after surgery in 10 patients with CRC (p<0.05). Further validation with an independent set of plasma samples (n = 180) indicated that miR-92 differentiates CRC from gastric cancer, IBD and normal subjects. This marker yielded a receiver operating characteristic curve area of 88.5%. At a cut-off of 240 (relative expression in comparison to RNU6B snRNA), the sensitivity was 89% and the specificity was 70% in discriminating CRC from control subjects.

CONCLUSION

MiR-92 is significantly elevated in plasma of patients with CRC and can be a potential non-invasive molecular marker for CRC screening.

Interaction of cigarette smoking with cyclooxygenase-2 on ulcerative colitis-associated neoplasia in mice

The interactions of cigarette smoking with COX-2 on colitis and colitis-associated adenoma formation were studied. Mice were induced with colitis and exposed to cigarette smoke (CS) and/or SC236 (a COX-2 inhibitor). Results indicated that CS did not alter acute colonic inflammation. Addition of SC236 abolished the induction of proliferation and oxidative damage by colitis. Chronic SC236 treatment abolished the promoting effect of CS on colonic adenoma formation, via suppression of COX-2- and VEGF-mediated proliferation and angiogenesis, and reversed bcl-2-mediated inhibition of apoptosis by CS. To conclude, COX-2 inhibitor could be an implication on cancer prevention in smokers with chronic colitis.

Shift of homeostasis from parenchymal regeneration to fibroblast proliferation induced by lipopolysaccharide-activated macrophages in gastric mucosal healing in vitro

Wound healing in the gastrointestinal tract is an orderly process involving orchestrated responses of various cell types. Lipopolysaccharides (LPS) are major components of the outer membrane of Gram-negative bacteria, which are known to impair gastric ulcer healing in animals. The influence of LPS on intercellular communication in wound healing, however, is unknown. We examined the effects of LPS-induced macrophage activation on the proliferative response in cultured rat gastric epithelial cells (RGM-1) and fibroblasts JHU-25. Rat peritoneal resident macrophages were activated with increasing doses of LPS. The supernatant from the activated macrophage preparation, designated as macrophage-conditioned medium, was then used to treat RGM-1 or JHU-25 cells. Cell proliferation and migration were determined by [(3)H]-thymidine incorporation and a monolayer wound-healing assay, respectively. Macrophage-conditioned medium significantly suppressed RGM-1 cell proliferation but had no effect on cell migration. The same medium, however, increased JHU-25 cell proliferation. LPS treatment alone suppressed JHU-25 cell proliferation while it had no effect on RGM-1 cell proliferation, indicating that the differential effects of the macrophage-conditioned medium on cell proliferation were elicited by the factors derived from macrophages. In this regard, tumor necrosis factor (TNF)-alpha stimulated while interleukin (IL)-1beta suppressed RGM-1 cell proliferation, suggesting that IL-1beta but not TNF-alpha may play a part in the mediation of the antiproliferative effect of macrophage-conditioned medium on gastric epithelial cells. In contrast, IL-1beta suppressed while TNF-alpha had no effect on JHU-25 cell proliferation. Collectively, LPS-activated macrophages delay gastric mucosal regeneration but promote fibroblast proliferation in vitro. Such changes may partly elucidate the detrimental effect of bacterial infection on tissue repair in the stomach.

Functional role of beta-adrenergic receptors in the mitogenic action of nicotine on gastric cancer cells

We previously reported that nicotine promoted gastric cancer cell growth via upregulation of cyclooxygenase 2 (COX-2). In the present study, we further investigated whether beta-adrenoceptors, protein kinase C (PKC), and extracellular signal-regulated kinase-1/2 (ERK1/2) were involved in the modulation of COX-2 expression and cell proliferation by nicotine in AGS, a human gastric adenocarcinoma cell line. Results showed that nicotine dose dependently increased the phosphorylation of EKR1/2 and the expression of AP-1 subunits c-fos and c-jun. In this connection, the ERK1/2 inhibitor U0126 abrogated the upregulation of AP-1 and COX-2 as well as cell proliferation induced by nicotine. Moreover, nicotine induced the translocation of PKC-betaI from cytosol to membrane and increased the total levels of PKC expression. Inhibition of PKC by staurosporine attenuated nicotine-induced ERK1/2 phosphorylation and COX-2 expression. Furthermore, atenolol and ICI 118,551, a beta1- and beta2-adrenoceptor antagonist, respectively, reversed the stimulatory action of nicotine on the expression of PKC, ERK1/2 phosphorylation, and COX-2 together with cell proliferation. Collectively, these results suggest that nicotine stimulates gastric cancer cell growth through the activation of beta-adrenoceptors and the downstream PKC-betaI/ERK1/2/COX-2 pathway.

Involvement of Kv1.1 and Nav1.5 in proliferation of gastric epithelial cells

In the present study, patch clamp experiments demonstrated the expression of multiple ionic currents, including a Ba2+-sensitive inward rectifier K+ current (IKir), a 4-aminopyridine- (4-AP) sensitive delayed rectifier K+ current (IKDR), and a nifedipine-sensitive, tetrodotoxin-resistant inward Na+ current (INa.TTXR) in the non-transformed rat gastric epithelial cell line RGM-1. RT-PCR revealed molecular identities of mRNAs for the functional ionic currents, including Kir1.2 for IKir, Kv1.1, Kv1.6, and Kv2.1 for IKDR, and Nav1.5 for INa.TTXR. Pharmacologic blockade of Kv and Nav, but not Kir, suppressed RGM-1 cell proliferation. To further elucidate which subtypes of the ion channels were involved in cell proliferation, RNA interference was employed to knockdown specific gene expression. Downregulation of Kv1.1 or Nav1.5 by RNA interference suppressed RGM-1 cell proliferation. To conclude, our study is the first to delineate the expression of ion channels and their functions as growth modulators in gastric epithelial cells.

Heparin increases human gastric carcinoma cell growth

BACKGROUND

Heparin has been widely used to prevent cancer-associated thromboembolism in cancer patients. Recent evidence reveals that heparin could modulate cell proliferation in the stomach. The effect of heparin on gastric cancer growth, however, is unknown. The effect of heparin on the proliferation of a human gastric adenocarcinoma cell line, BGC-823, was investigated.

MATERIALS AND METHODS

Cell proliferation was assessed by [3H]-thymidine incorporation. The expressions of several growth-related genes were determined by RT-PCR and Western blot.

RESULTS

Heparin significantly increased cell proliferation in BGC-823 cancer cells by 15.5% at the dose of 0.2 microg/ml. Heparin also up-regulated c-Myc protein expression by 14.4%. In contrast, mRNA and protein levels of epidermal growth factor receptor (EGFR) were, respectively, down-regulated by 12.7% and 8.2% with no effect on cyclooxygenase-2 mRNA or protein expression.

CONCLUSION

Our results suggest that heparin can promote the proliferation and up-regulation of c-Myc protein expression in gastric cancer cells.

Dual inhibition of 5-LOX and COX-2 suppresses colon cancer formation promoted by cigarette smoke

Previous studies indicate that the arachidonic acid-metabolizing enzymes COX-2 and 5-LOX are overexpressed during the process of colonic adenoma formation promoted by cigarette smoke. The aims of the present study were to investigate whether there exists a relationship between COX-2 and 5-LOX, and whether dual inhibition of COX-2 and 5-LOX has an anticarcinogenic effect in the colonic tumorigenesis promoted by cigarette smoke. Results showed that pretreating colon cancer cells with cigarette smoke extract (CSE) promoted colon cancer growth in the nude mouse xenograft model. Inhibition of COX-2 or 5-LOX reduced the tumor size. In the group treated with COX-2-inhibitor, the PGE2 level decreased while the LTB4 level increased. In contrast, in the 5-LOX-inhibitor treated group, the LTB4 level was reduced and the PGE2 level was unchanged. However, combined treatment with both COX-2 and 5-LOX inhibitors further inhibited the tumor growth promoted by CSE over treatment with either COX-2-inhibitor or 5-LOX-inhibitor alone. This was accompanied by the downregulation of PGE2 and LTB4. In an in vitro study, we found that the action of CSE on colon cancer cells was mediated by 5-LOX DNA demethylation. In summary, these results indicate that inhibition of COX-2 may lead to a shunt of arachidonic acid metabolism towards the leukotriene pathway during colonic tumorigenesis promoted by CSE. Suppression of 5-LOX did not induce such a shunt and produced a better response. Therefore, 5-LOX inhibitor is more effective than COX-2 inhibitor, and blocker of both COX-2 and 5-LOX may present a superior anticancer profile in cigarette smokers.

Tumor necrosis factor-alpha stimulates gastric epithelial cell proliferation

TNF-alpha is a cytokine produced during gastric mucosal injury. We examined whether TNF-alpha could promote mucosal repair by stimulation of epithelial cell proliferation and explored further the underlying mechanisms in a rat gastric mucosal epithelial cell line (RGM-1). TNF-alpha treatment (1-10 ng/ml) for 12 or 24 h significantly increased cell proliferation but did not induce apoptosis in RGM-1 cells. TNF-alpha treatment significantly increased cytosolic phospholipase A(2) and cyclooxygenase-2 (COX-2) protein expression and PGE(2) level but did not affect the protein levels of EGF, basic fibroblast growth factor, and COX-1 in RGM-1 cells. The mRNA of TNF receptor (TNF-R) 2 but not of TNF-R1 was also increased. Dexamethasone dose dependently inhibited the stimulatory effect of TNF-alpha on cell proliferation, which was associated with a significant decrease in cellular COX-2 expression and PGE(2) level. A selective COX-2 inhibitor 3-(3-fluorophenyl)-4-[4-(methylsulfonyl)phenyl]-5,5-dimethyl-(5)H-furan-2-one (DFU) by itself had no effect on basal cell proliferation but significantly reduced the stimulatory effect of TNF-alpha on RMG-1 cells. Combination of dexamethasone and DFU did not produce an additive effect. PGE(2) significantly reversed the depressive action of dexamethasone on cell proliferation. These results suggest that TNF-alpha plays a regulatory role in epithelial cell repair in the gastric mucosa via the TNF-alpha receptor and activation of the arachidonic acid/PG pathway.

Contributory role of 5-lipoxygenase and its association with angiogenesis in the promotion of inflammation-associated colonic tumorigenesis by cigarette smoking

Our previous study shows that cigarette smoking can promote inflammation-associated adenoma formation in the mouse colon, but the underlying mechanism remains unknown. Several studies suggest that there is a link between 5-lipoxygenase (5-LOX) and carcinogenesis in humans and animals. In the present study, we aims to investigate whether the promoting action of cigarette smoke on inflammation-associated colon cancer formation is associated with 5-LOX activation in mice. Results showed that exposure to the mainstream smoke of unfiltered cigarettes enhanced the 5-LOX protein expression in the inflammation-associated colonic adenomas. It was accompanied with an up-regulation of matrix metalloproteinase-2 (MMP-2) and vascular endothelial growth factor (VEGF). Both are the key angiogenic factors for tumorigenesis. 5-LOX inhibitors decreased the incidence of colonic adenoma formation and reduced angiogenesis, MMP-2 activity and VEGF protein expression in the colons of these animals. Taken together, these results strongly suggest that cigarette smoke can induce 5-LOX expression which plays an important role in activation of MMP-2 and VEGF to induce angiogenic process and promotion of inflammation-associated adenoma formation in mice.

Anti-tumorigenic and Pro-apoptotic effects of CKBM on gastric cancer growth in nude mice

Natural botanical products can be integrated with western medicine to optimize the treatment outcome, increase immune function and minimize the side effects from western drug treatment. CKBM is a combination of herbs and yeasts formulated based on traditional Chinese medicinal principles. Previous study has demonstrated that CKBM is capable of improving immune responsiveness through the induction of cytokine mediators, such as TNF-alpha and IL-6. In this study, we aimed to investigate the effect of this immunomodulatory drug on gastric cancer growth using a human xenograft model. Gastric cancer tissues were implanted subcutaneously into athymic nude mice followed by a 14-day or 28-day of CKBM treatment. Results showed that higher doses of CKBM (0.4 or 0.8 ml/mouse/day) produced a dose-dependent inhibitory effect on gastric tumor growth after 28-day drug treatment. This was associated with a decrease of cellular proliferation by 30% with concomitant increase in apoptosis by 97% in gastric tumor cells when compared with the control group. In contrast, CKBM showed no effect on angiogenesis in gastric tumors. This study demonstrates the anti-tumorigenic action of CKBM on gastric cancer probably via inhibition of cell proliferation and induction of apoptosis, and provides future potential targets of this drug candidate on cancer therapy.

Differential effects of cigarette smoke extracts on cell proliferation in gastric and colon cells

Substantial evidence show a higher incidence of gastric cancer in smokers than nonsmokers and that cigarette smoking is highly associated with colon cancer. The present study was designed to examine the effect of cigarette smoke extracts on gastric and colon cancer cell proliferation, which is important for tumor growth. Two different cell lines were used. One was gastric cancer cell line AGS, and the other was colon cancer cell line HT-29. It was found that cigarette smoke extracts stimulated cell proliferation and c-myc expression in AGS cells. Furthermore, this proliferative action was partially blocked by the c-myc antisense. However, the extracts significantly inhibited HT-29 cell proliferation and suppressed c-myc expression. In conclusion, cigarette smoke extracts stimulated AGS cell proliferation, while inhibiting HT-29 proliferation, which were partially mediated by a c-myc-related pathway. The former action may play a contributory role in the carcinogenic action of cigarette smoking in the stomach.

Effect of polysaccharides from Angelica sinensis on gastric ulcer healing

Our previous study showed that a crude extract from Angelica sinensis (ASCE), which mainly consisted of polysaccharides, significantly promoted migration and proliferation of normal gastric epithelial cells. These results strongly suggest that ASCE has a direct wound healing effect on gastric mucosa. However, there is no report concerning the effect of ASCE on gastric ulcer healing in animal models. In this study, we found that ASCE promoted ulcer healing. The area of the ulcer was reduced. This was accompanied with a significant increase in mucus synthesis when compared with the control. Angiogenesis was inhibited by the treatment of ASCE. Cell proliferation, ODC and EGFR protein expression was not affected in this process. Thus, the mechanism of how ASCE accelerates ulcer healing in addition to its effect on mucus synthesis remains to be investigated.

A 3.0-kDa low molecular weight heparin promotes gastric ulcer healing in rats

BACKGROUND

Previous studies have shown that intragastric administration of unfractionated heparin enhances gastric ulcer healing in rats. As the large molecule of heparin may be partially degraded in the upper gastrointestinal tract, it is likely that fragments of heparin, derived from the unfractionated parent compound, are involved in the anti-ulcer action in the stomach. Therefore, it is possible that low molecular weight heparin may have a similar ulcer healing effect.

METHODS

Male Sprague-Dawley rats with acetic acid-induced gastric ulcers were given a 3.0-kDa low molecular weight heparin (0.6-6.0 mg/kg) intravenously or intragastrically once daily for 4 days. Ulcer healing, mucosal histological changes, angiogenesis and gastric mucus production both in vivo and in vitro were determined. The bleeding time was measured to indicate the anticoagulation activity.

RESULTS

Both intravenous and intragastric low molecular weight heparin dose dependently accelerated gastric ulcer healing, which was accompanied by a significant increase in mucosal regeneration and proliferation, angiogenesis and mucus content in the stomach. The drug also stimulated the mucus production in MKN-28 cells. Drug administration by either route did not alter the bleeding time in rats.

CONCLUSIONS

A 3.0-kDa low molecular weight heparin possesses an ulcer healing effect similar to that of unfractionated heparin in the stomach of the rat. This smaller molecular drug is superior to the unfractionated form, does not affect the coagulation activity and may show better absorption in the gastrointestinal tract.

Modulation of heme oxygenase in tissue injury and its implication in protection against gastrointestinal diseases

Heme oxygenase (HO) is the rate-limiting enzyme in the catabolism of heme, followed by production of biliverdin, free iron and carbon monoxide (CO). There are three isoforms of HO: HO-1 is highly inducible, whereas HO-2 and HO-3 are constitutively expressed. In addition to heme, a variety of nonheme compounds, including heavy metals, cytokines, endotoxins and heat shock stress are strong inducers of HO-1 expression. Many studies indicated that induction of HO-1 is associated with a protective response due to the removal of free heme, which is shown to be toxic. However, recent studies demonstrated that the expression of HO-1 in response to different inflammatory mediators could contribute in part to the resolution of inflammation and have protective effects on brain, liver, kidney and lung against injuries. These beneficial effects seem to be due to the production of bile pigment biliverdin and bilirubin that is a potent antioxidant, as well as the release of iron and CO. However, there are few studies concerning the relationship between HO-1 and inflammation as well as injury in the gut. Interestingly, a preliminary study implicated that induction of HO-1 expression in a colonic damage model induced by trinitrobenzene sulfonic acid played a critical protective role, indicating that activation of HO-1 could act as a natural defensive mechanism to alleviate inflammation and tissue injury in the gastrointestinal tract.

Epidermal growth factor and its receptor in chronic active gastritis and gastroduodenal ulcer before and after Helicobacter pylori eradication

BACKGROUND

Helicobacteria pylori infection of gastroduodenal mucosa is strongly associated with gastritis and peptic ulcer disease. The aims of the present study were to compare the gastroduodenal mucosal levels of epidermal growth factor (EGF) and its receptor (EGFR) among H. pylori-negative controls and H. pylori infected patients with chronic active gastritis or gastroduodenal ulcer before and after H. pylori eradication.

METHODS

The protein levels of EGF in mucosal tissues and saliva were determined by a solid-phase enzyme-linked immunosorbent assay (ELISA). Repeat transcription-polymerase chain reaction and the following polymerase chain reaction ELISA were employed to examine the mucosal EGFR mRNA expression.

RESULTS

Mucosal injury and H. pylori infection increased EGF protein levels and EGFR mRNA expression in the antral mucosa. The concentration of EGF in saliva was not affected by mucosal damage or H. pylori infection. Successful H. pylori eradication normalized the EGFR mRNA back to its basal level 6 weeks after treatment. However, after unsuccessful eradication their high levels in the antrum persisted. All patients experienced ulcer healing after drug treatment, regardless of H. pylori eradication.

CONCLUSIONS

Mucosal damage increased the expression of EGF protein and EGFR mRNA in the gastric mucosa. H. pylori could induce the expression of EGFR but not the EGF in the antral mucosa. The expression of EGFR could be a contributing factor for ulcer healing in patients with H. pylori infection.

A mechanistic study of proliferation induced by Angelica sinensis in a normal gastric epithelial cell line

It has been reported that an extract from Angelica sinensis mainly consisting of polysaccharides (95%) prevented ethanol- or indomethacin-induced gastric mucosal damage (Cho CH et al. Planta Med 2000;66:348-51). However, it is not known whether Angelica sinensis has a direct stimulatory effect on the healing of gastric mucosal lesions. To study the hypothesis that Angelica sinensis has a direct mucosal healing effect in rats and in isolated gastric epithelial cells, we assessed the wound repair in both animals and normal cell culture (RGM-1), as well as [3H]thymidine incorporation, ornithine decarboxylase (ODC) activity, and ODC protein and c-Myc protein expression after different treatments in RGM-1 cells. We found that Angelica sinensis crude extract (ASCE) dose-dependently enhanced gastric ulcer healing in rats and promoted wound repair in RGM-1 cells. It also significantly stimulated [3H]thymidine incorporation and ODC activity in RGM-1 cells in a concentration-dependent manner. ODC and c-Myc protein expression was also increased as a result of this process. DL-alpha-difluoromethyl-ornithine repressed the [3H]thymidine incorporation and ODC activity induced by ASCE. Pretreatment with c-Myc antisense oligodeoxynucleotides blocked the stimulatory action of ASCE on [3H]thymidine incorporation and ODC protein expression. These data suggest that ASCE has a direct mucosal healing effect on gastric epithelial cells, while ODC and c-Myc are closely associated with this effect.

Subcellular distribution of ankyrin in developing rabbit heart--relationship to the Na+-Ca2+ exchanger

Ankyrins are a multigene family of proteins that function as adapters between the cytoskeleton and trans-membrane proteins, such as ion channels. Previous studies have shown the linkage between ankyrin and ionic transport proteins such as Na+-K+ ATPase, voltage-dependent Na+ channels and Ca2+ channels. In the present study, we have investigated the subcellular distribution of ankyrin and its relationship to the Na+-Ca2+ exchange protein in immature and adult rabbit ventricular myocytes. Isolated single cardiomyocytes from neonatal, juvenile and adult rabbit hearts were examined by immunofluorescence labeling techniques, using antibodies against ankyrin and the Na+-Ca2+ exchanger. We found that in neonatal rabbit cardiac myocytes, ankyrin labeling was mainly present at the Z disk, whereas the Na+-Ca2+ exchanger was only present on the peripheral sarcolemma. At 2 weeks of age, ankyrin labeling was still predominantly observed at the level of the Z disks as well as in the partially developed T-tubules. In the adult cells, however, ankyrin and the Na+-Ca2+ exchanger seem to be co-localized within T-tubules and at the costamere region of the peripheral sarcolemma. Immunogold labeling studies at the higher resolution electron microscopic level using cyrosection tissues of rabbit heart at different ages confirm these findings. These results indicate that the distribution pattern of ankyrin and the Na+-Ca2+ exchanger changes with development in rabbit ventricular myocytes.