Targeted activation of human Vγ9Vδ2-T cells controls epstein-barr virus-induced B cell lymphoproliferative disease

Epstein-Barr virus-induced lymphoproliferative disease (EBV-LPD) after transplantation remains a serious and life-threatening complication. Herein we showed that the aminobisphosphonate pamidronate-expanded human Vγ9Vδ2-T cells efficiently killed EBV-transformed autologous lymphoblastoid B cell lines (EBV-LCL) through γ/δ-TCR and NKG2D receptor triggering and Fas and TRAIL engagement. By inoculation of EBV-LCL in Rag2(-/-)γc(-/-) mice and humanized mice, we established lethal EBV-LPD with characteristics close to those of the human disease. Adoptive transfer of pamidronate-expanded Vγ9Vδ2-T cells alone effectively prevented EBV-LPD in Rag2(-/-)γc(-/-) mice and induced EBV-LPD regression in EBV(+) tumor-bearing Rag2(-/-)γc(-/-) mice. Pamidronate treatment inhibited EBV-LPD development in humanized mice through selective activation and expansion of Vγ9Vδ2-T cells. This study provides proof-of-principle for a therapeutic approach using pamidronate to control EBV-LPD through Vγ9Vδ2-T cell targeting.

Chromodomain helicase/adenosine triphosphatase DNA binding protein 1-like (CHD1l) gene suppresses the nucleus-to-mitochondria translocation of nur77 to sustain hepatocellular carcinoma cell survival

Amplification of 1q21 has been detected in 58% to 78% of primary hepatocellular carcinoma cases, suggesting that one or more oncogenes within the amplicon play a critical role in the development of this disease. The chromodomain helicase/adenosine triphosphatase DNA binding protein 1-like gene (CHD1L) is a recently identified oncogene localized at 1q21. Our previous studies have demonstrated that CHD1L has strong tumorigenic ability and confers high susceptibility to spontaneous tumors in a CHD1L-transgenic mouse model. In this study, we demonstrate that the antiapoptotic ability of CHD1L is associated with its interaction with Nur77, a critical member of a p53-independent apoptotic pathway. As the first cellular protein identified to bind Nur77, CHD1L is able to inhibit the nucleus-to-mitochondria translocation of Nur77, which is the key step of Nur77-mediated apoptosis, resulting in the hindrance of the release of cytochrome c and the initiation of apoptosis. Knock-down of CHD1L expression by RNA interference could rescue the mitochondrial targeting of Nur77 and the subsequent apoptosis. Further studies found that the C-terminal Macro domain of CHD1L is responsible for the interaction with Nur77, and a CHD1L mutant lacking residues 600-897 failed to interact with Nur77 and prevented Nur77-mediated apoptosis. More importantly, we found that the inhibition of Nur77-mediated apoptosis by endogenous CHD1L is a critical biological cellular process in hepatocarcinogenesis.

CONCLUSION

We demonstrate in this study that overexpression of CHD1L could sustain tumor cell survival by preventing Nur77-mediated apoptosis.

EGCG inhibits proliferation, invasiveness and tumor growth by up-regulation of adhesion molecules, suppression of gelatinases activity, and induction of apoptosis in nasopharyngeal carcinoma cells

(-)-Epigallocatechin-3-gallate (EGCG), a major green tea polyphenol, has been shown to inhibit the proliferation of a variety of tumor cells. Epidemiological studies have shown that drinking green tea can reduce the incidence of nasopharyngeal carcinoma (NPC), yet the underlying mechanism is not well understood. In this study, the inhibitory effect of EGCG was tested on a set of Epstein Barr virus-negative and -positive NPC cell lines. Treatment with EGCG inhibited the proliferation of NPC cells but did not affect the growth of a non-malignant nasopharyngeal cell line, NP460hTert. Moreover, EGCG treated cells had reduced migration and invasive properties. The expression of the cell adhesion molecules E-cadherin and β-catenin was found to be up-regulated by EGCG treatment, while the down-regulation of matrix metalloproteinases (MMP)-2 and MMP-9 were found to be mediated by suppression of extracellular signal-regulated kinase (ERK) phosphorylation and AP-1 and Sp1 transactivation. Spheroid formation by NPC cells in suspension was significantly inhibited by EGCG. Oral administration of EGCG was capable of suppressing tumor growth in xenografted mice bearing NPC tumors. Treatment with EGCG was found to elevate the expression of p53 and p21, and eventually led to apoptosis of NPC cells via caspase 3 activation. The nuclear translocation of NF-κB and β-catenin was also suppressed by EGCG treatment. These results indicate that EGCG can inhibit the proliferation and invasiveness, and induce apoptosis, of NPC cells, making it a promising agent for chemoprevention or adjuvant therapy of NPC.

The ATP-binding cassette transporter ABCF1 is a hepatic oncofetal protein that promotes chemoresistance, EMT and cancer stemness in hepatocellular carcinoma

ATP-binding cassette (ABC) transporters mediate multidrug resistance and cancer stem cell properties in various model systems. Yet, their biological significance in cancers, especially in hepatocellular carcinoma (HCC), remains unclear. In this study, we investigated the function of ABCF1 in HCC and explored its potential as a therapeutic target. ABCF1 was highly expressed in fetal mouse livers but not in normal adult livers. ABCF1 expression was upregulated in HCCs. These results demonstrate that ABCF1 functions as a hepatic oncofetal protein. We further demonstrated elevated ABCF1 expression in HCC cells upon acquiring chemoresistance. Suppression of ABCF1 by siRNA sensitized both parental cells and chemoresistant cells to chemotherapeutic agents. Reversely, ABCF1 overexpression promoted chemoresistance and drug efflux. In addition, overexpression of ABCF1 enhanced migration, spheroid and colony formation and epithelial-mesenchymal transition (EMT) induction. RNA sequencing analysis revealed EMT inducers HIF1α/IL8 and Sox4 as potential mediators for the oncogenic effect of ABCF1 in HCC progression. Together, this study illustrates that ABCF1 is a novel potential therapeutic target for HCC treatment.

Integrated mRNA and microRNA transcriptome sequencing characterizes sequence variants and mRNA-microRNA regulatory network in nasopharyngeal carcinoma model systems

Nasopharyngeal carcinoma (NPC) is a prevalent malignancy in Southeast Asia among the Chinese population. Aberrant regulation of transcripts has been implicated in many types of cancers including NPC. Herein, we characterized mRNA and miRNA transcriptomes by RNA sequencing (RNASeq) of NPC model systems. Matched total mRNA and small RNA of undifferentiated Epstein–Barr virus (EBV)-positive NPC xenograft X666 and its derived cell line C666, well-differentiated NPC cell line HK1, and the immortalized nasopharyngeal epithelial cell line NP460 were sequenced by Solexa technology. We found 2812 genes and 149 miRNAs (human and EBV) to be differentially expressed in NP460, HK1, C666 and X666 with RNASeq; 533 miRNA–mRNA target pairs were inversely regulated in the three NPC cell lines compared to NP460. Integrated mRNA/miRNA expression profiling and pathway analysis show extracellular matrix organization, Beta-1 integrin cell surface interactions, and the PI3K/AKT, EGFR, ErbB, and Wnt pathways were potentially deregulated in NPC. Real-time quantitative PCR was performed on selected mRNA/miRNAs in order to validate their expression. Transcript sequence variants such as short insertions and deletions (INDEL), single nucleotide variant (SNV), and isomiRs were characterized in the NPC model systems. A novel TP53 transcript variant was identified in NP460, HK1, and C666. Detection of three previously reported novel EBV-encoded BART miRNAs and their isomiRs were also observed. Meta-analysis of a model system to a clinical system aids the choice of different cell lines in NPC studies. This comprehensive characterization of mRNA and miRNA transcriptomes in NPC cell lines and the xenograft provides insights on miRNA regulation of mRNA and valuable resources on transcript variation and regulation in NPC, which are potentially useful for mechanistic and preclinical studies.

•

Using RNASeq we characterized the mRNA and miRNA transcriptomes in NPC and NP models.

•

2812 Genes and 149 miRNAs (human and EBV) were differentially expressed in NPC vs NP models.

•

533 miRNA–mRNA target pairs were inversely regulated in HK1, C666, and X666 vs NP460.

•

ECM, β1 integrin, PI3K/AKT, EGFR, ErbB, and Wnt pathways appeared to be deregulated in NPC.

•

A novel TP53 mutation was identified in NP460, HK1, and C666.

Identification of a novel tumor transforming gene GAEC1 at 7q22 which encodes a nuclear protein and is frequently amplified and overexpressed in esophageal squamous cell carcinoma

By comparative DNA fingerprinting, we identified a 357-bp DNA fragment frequently amplified in esophageal squamous cell carcinomas (ESCC). This fragment overlaps with an expressed sequence tag mapped to 7q22. Further 5' and 3'-rapid amplification of cDNA ends revealed that it is part of a novel, single-exon gene with full-length mRNA of 2052 bp and encodes a nuclear protein of 109 amino acids ( approximately 15 kDa). This gene, designated as gene amplified in esophageal cancer 1 (GAEC1), was located within a 1-2 Mb amplicon at 7q22.1 identified by high-resolution 1 Mb array-comparative genomic hybridization in 6/10 ESCC cell lines. GAEC1 was ubiquitously expressed in normal tissues including esophageal and gastrointestinal organs; with amplification and overexpression in 6/10 (60%) ESCC cell lines and 34/99 (34%) primary tumors. Overexpression of GAEC1 in 3T3 mouse fibroblasts caused foci formation and colony formation in soft agar, comparable to H-ras and injection of GAEC1-transfected 3T3 cells into athymic nude mice formed undifferentiated sarcoma in vivo, indicating that GAEC1 is a transforming oncogene. Although no significant correlation was observed between GAEC1 amplification and clinicopathological parameters and prognosis, our study demonstrated that overexpressed GAEC1 has tumorigenic potential and suggest that overexpressed GAEC1 may play an important role in ESCC pathogenesis.

EBNA1-specific luminescent small molecules for the imaging and inhibition of latent EBV-infected tumor cells

An EBNA1-specific small molecule (JLP2) has been synthesised. As a strong binder and dimerization inhibitor of EBNA1 in vitro, JLP2 may be used as a selective luminescent agent for the imaging and inhibition of latent EBV-infected cancer cells.

Nasopharyngeal carcinoma cells promote regulatory T cell development and suppressive activity via CD70-CD27 interaction

Despite the intense CD8+ T-cell infiltration in the tumor microenvironment of nasopharyngeal carcinoma, anti-PD-1 immunotherapy shows an unsatisfactory response rate in clinical trials, hindered by immunosuppressive signals. To understand how microenvironmental characteristics alter immune homeostasis and limit immunotherapy efficacy in nasopharyngeal carcinoma, here we establish a multi-center single-cell cohort based on public data, containing 357,206 cells from 50 patient samples. We reveal that nasopharyngeal carcinoma cells enhance development and suppressive activity of regulatory T cells via CD70-CD27 interaction. CD70 blocking reverts Treg-mediated suppression and thus reinvigorate CD8+ T-cell immunity. Anti-CD70+ anti-PD-1 therapy is evaluated in xenograft-derived organoids and humanized mice, exhibiting an improved tumor-killing efficacy. Mechanistically, CD70 knockout inhibits a collective lipid signaling network in CD4+ naïve and regulatory T cells involving mitochondrial integrity, cholesterol homeostasis, and fatty acid metabolism. Furthermore, ATAC-Seq delineates that CD70 is transcriptionally upregulated by NFKB2 via an Epstein-Barr virus-dependent epigenetic modification. Our findings identify CD70+ nasopharyngeal carcinoma cells as a metabolic switch that enforces the lipid-driven development, functional specialization and homeostasis of Tregs, leading to immune evasion. This study also demonstrates that CD70 blockade can act synergistically with anti-PD-1 treatment to reinvigorate T-cell immunity against nasopharyngeal carcinoma.

The Wnt modulator ICG‑001 mediates the inhibition of nasopharyngeal carcinoma cell migration in vitro via the miR‑150/CD44 axis

The Wnt signaling pathway is known to serve an important role in the control of cell migration. The present study analyzed the mechanisms underlying the in vitro modulation of the migration of nasopharyngeal carcinoma (NPC) cells by the CREB‑binding protein/catenin antagonist and Wnt modulator ICG‑001. The results revealed that ICG‑001‑mediated inhibition of tumor cell migration involved downregulated mRNA and protein expression of the Wnt target gene cluster of differentiation (CD)44. It was also demonstrated that ICG‑001 downregulated the expression of CD44, and this effect was accompanied by restored expression of microRNA (miRNA)‑150 in various NPC cell lines. Using a CD44 3'‑untranslated region luciferase reporter assay, miR‑150 was confirmed to be a novel CD44‑targeting miRNA, which could directly target CD44 and subsequently regulate the migration of NPC cells. The present study provides further insight into the inhibition of tumor cell migration through the modulation of miRNA expression by the Wnt modulator ICG‑001.

Abstract 1046: The role of NF-kB activation in the immortalization of nasopharyngeal epithelial cells

NF-κB is a key regulator of inflammatory response and is frequently activated in human cancers including nasopharyngeal carcinoma (NPC), which is closely associated with Epstein-Barr virus (EBV) infection and a common cancer in Southern China including Hong Kong. However, it is well-established that EBV infection alone is not sufficient for NPC development. Other genetic alterations in host cells and the interaction between EBV infection and host cell microenvironment are required for NPC development. Our group has been involved in illustrating molecular events underlying the immortalization of nasopharyngeal epithelial (NPE) cells. Molecular changes which facilitate immortalization may represent early genetic events in human carcinogenesis. We found that the activation of NF-κB was a common feature in telomerase-immortalized NPE cell lines. We further showed that canonical NF-κB activation pathway was involved in the immortalization of NPE cells. The activation of NF-κB was essential for the proliferation of the immortalized NPE cells because suppression of NF-κB activity could selectively inhibit the proliferation of immortalized but not primary NPE cells. The upregulation of c-Myc and Bmi-1, known to promote cell proliferation, were associated with NF-κB activation in the immortalized NPE cell lines. Interestingly, mTOR was found to be the upstream activator of NF-κB. We further showed that EGFR/Erk(1/2) pathway was the upstream regulator of mTOR/NF-κB pathway, revealing the pathway of EGFR/Erk(1/2)/mTOR/NF-κB for NF-κB activation in telomerase-immortalized NPE cells. Elucidation of specific pathway leading to NF-κB activation in immortalized NPE cells may open up opportunity for early intervention to suppress or prevent NPC development.

Citation Format: George Sai-Wah Tsao, Dan Dan Zhu, Jun Zhang, Wen Deng. The role of NF-kB activation in the immortalization of nasopharyngeal epithelial cells. [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 1046. doi:10.1158/1538-7445.AM2015-1046

Abstract 2957: Nasopharyngeal cancer

Background:

Nasopharyngeal cancer (NPC) is associated with a poor survival rate. The ability of cancer cells to evade apoptosis and exhibit limitless replication potential allows for the progression of cancer. The aim of this study was to investigate in vitro the effect of the isoflavone phenoxodiol on human NPC cell line and T cells, which has previously been shown to inhibit cell proliferation and promote apoptosis in a range of cancer cell lines and in anti-CD3/anti-CD28-activated murine splenocytes.

Methods:

Four NPC cancer cell lines-C666, C17, and paired NPC43 EBV-positive and its respective EBV-negative cell lines were cultured in vitro, and then treated with phenoxodiol for 72h or 5 days. The migration and proliferation was investigated by transwell and XTT, respectively. Conditioned medium of treated NPC cell lines were collected and incubated with human PBMC for 5 days. CD4 and CD8 surface staining were analyzed by flow cytometry.

Result:

We demonstrated that phenoxodiol inhibited NPC migration and cell proliferation (IC50 4µM). Among all the NPC cell lines, the proliferation effect on EBV-negative cell line (NPC43-ve) is least responsive to phenoxodiol. A dose-dependent of apoptosis in NPC cell lines by phenoxodiol [early apoptotic cells (Annexin V+/PI- at 1µM); late apoptotic cells (Annexin V+/PI+ at 2µM), and necrotic cells (Annexin V-/PI+, at 4µM) were distinguished. Interestingly, phenoxodiol reduced frequency of CD4 T cells while promoting the number of CD8 T cells.

Conclusions:

Phenoxodiol demonstrates an ability in NPC cancer cells to induce its apoptosis while inhibit its migration and proliferation. Moreover, the ability of phenoxodiol to modulate T cells population indicates that phenoxodiol would be effective as a potential future treatment for NPC.

Note: This abstract was not presented at the meeting.

Citation Format: Ngar Woon Kam, See Wing Chan, George Sai-Wah Tsao, Xin-Yuan Guan, Dora Lai Wan Kwong. Nasopharyngeal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2957.

Establishment and characterization of a human non-small cell lung cancer cell line

Lung cancer is one of the most common causes of cancer death worldwide. Although many efforts have been made to explore the mechanisms involved in the development of lung cancer, the genetic events involved in the pathogenesis of lung cancer are still unclear. For a better mechanistic scope of study, a well-established cellular model is essential. We report the establishment of a squamous cell carcinoma (SCC) cell line of human lung, SCC-37. Chromosomal abnormalities and global genomic alterations of SCC-37 were studied by spectral karyotyping (SKY) and comparative genomic hybridization (CGH), respectively. Results showed that SCC-37 was a hypodiploid with complex chromosomal rearrangements. Some of the alterations, such as the gain of 1q25-qter in SCC-37, have been correlated to the tumor recurrence of non-small cell lung cancer (NSCLC). Other interesting findings include the amplification of 3q25-qter and 12q13, suggesting the existence of important oncogenes in the amplicons. This cell line may thus provide a useful cellular resource for studying the pathogenesis of SCC of the lung in the future.

Abstract 2037: Cyclin D1 overexpression supports stable EBV infection in nasopharyngeal epithelial cells

Poorly or undifferentiated nasopharyngeal carcinoma (NPC) is regularly associated with Epstein-Barr virus (EBV) infection. EBV infection of premalignant nasopharyngeal epithelial cells has been postulated to play an important role in the pathogenesis of nasopharyngeal carcinoma. We have previously reported that genetic alterations could be detected in premalignant nasopharyngeal epithelial tissues. It is not clear if these genetic alterations may associate with the establishment of EBV infection. In this study, we have examined the role of cyclin D1 in supporting EBV infection in nasopharyngeal epithelial cells. While cyclin D1 is commonly expressed in nasopharyngeal carcinoma tissues we found that overexpression of cycline D1 is readily detected in dysplastic nasopharyngeal epithelial closely associated with EBV infection. Furthermore, using a panel of immortalized nasopharyngeal epithelial cells, we demonstrated that overexpression of cyclin D1 or CKD4 supports EBV infection and result in the establishment of stable EBV infected nasopharyngeal cell lines. We also observed that EBV infection induced growth inhibition and senescence in nasopharyngeal epithelial cells, which may be the underlying reason for low detection rate of EBV infection in healthy nasopharyngeal epithelial tissues. However, cyclin D1 overexpression suppressed senescence and differentiation in the immortalized nasopharyngeal epithelial cells, suggesting cyclin D1 may play an important role in supporting EBV infection in these cells. We postulated that the altered expression of cyclin D1 or CDK4 in premalignant nasopharyngeal epithelial cells may over-ride the growth suppression effects of EBV infection and support EBV latent infection in premalignant nasopharyngeal epithelial cells. Acknowledgement: This study is sponsored by grant support received from the Hong Kong Research Grant Council (Grant number: GRF780911 and AoE /M-06/08)

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2037. doi:1538-7445.AM2012-2037

Abstract 2460: Epstein-Barr virus infection confer stress-resistant property in immortalized nasopharyngeal epithelial cells

Epstein-Barr virus (EBV) infection has been postulated to be an early event involved in the pathogenesis of NPC. The lack of representative premalignant nasopharyngeal epithelial cell system for EBV infection has hampered research investigation into the regulation and involvement of EBV infection in NPC pathogenesis. We have compared the efficiency of EBV infection in nasopharyngeal epithelial cells with different biological properties including immortalized, primary and cancerous nasopharyngeal epithelial cells. EBV infection could be achieved in all the nasopharyngeal epithelial cells examined with variable infection rate. TGF-β effectively enhanced EBV infection into nasopharyngeal epithelial cells both in the immortalized and primary nasopharyngeal epithelial cells. Stable infection of EBV was achieved in a telomerase-immortalized nasopharyngeal epithelial cell line, NP460hTert. The expression pattern of EBV-encoded genes and biological properties of this EBV infected cell line upon long term propagation were monitored. The EBV-infected nasopharyngeal epithelial cells acquired anchorage independent growth in soft-agar and exhibited invasive growth properties upon prolonged propagation. A distinguish feature of this EBV-infected nasopharyngeal epithelial cell model was its enhanced ability to survive under growth factor and nutrient starvation. This was evidenced by the suppressed activation of apoptotic markers and sustained activation of pAkt of EBV-infected cells compared to control cells under nutrient starvation. Examination of cytokine profiles of EBV-infected NP460hTert cells to nutrient and growth factor deprivation revealed upregulation expression of MCP-1 and GRO-α. The establishment of a stable EBV infection model of premalignant nasopharyngeal epithelial cells will facilitate research investigation into the pathogenic role of EBV in NPC development.

Acknowlegement: The authors wish to acknowlege the funding support from the Research Grant Council (Hong Kong) and the Area of Excellence on Nasopharyangeal Carcinoma Research Center (Hong Kong).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2460.

Abstract 5445: Suberoylanilide hydroxamic acid induces Epstein-Barr virus lytic cycle and enhanced apoptosis in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) has uniquely high prevalence in Southern Chinese populations and a predilection to affect young adult males. Epstein-Barr virus (EBV) is harbored in every tumour cell of NPC but it persists in tightly latent form expressing few viral proteins and evading the immune system. Induction of EBV lytic cycle will lead to expression of a much larger number of viral proteins which may serve as potential therapeutic targets against the cancer. We reported that suberoylanilide hydroxamic acid (SAHA), a FDA-approved histone deacetylase inhibitor, could strongly induce viral lytic cycle in EBV-positive gastric carcinoma cells. Here, we demonstrated that SAHA (at 5-10 μM) could potently induce EBV lytic cycle in a panel of EBV-positive NPC cell lines, as evidenced by increased viral DNA replication, expression of immediate early (Zta and Rta), early (BMRF1) and late (VCA-p40 and gp350/220) viral lytic proteins and production of infectious viral particles. Immunofluorescent staining demonstrated expression of viral lytic proteins in more than 40% of the NPC cells. Enhanced killing of EBV-positive NPC cells when compared with that of EBV-negative counterparts was observed and cleaved form of PARP was predominantly expressed in EBV-positive than EBV-negative NPC cells, following treatment with SAHA for 24, 48 and 72 hours. The kinetics of expression of cleaved PARP correlated with that of Zta viral protein in EBV-positive NPC cells. In conclusion, SAHA is found to be a potent EBV lytic cycle inducing agent and mediates enhanced apoptosis of NPC cells. Further investigation into SAHA's development as a novel virus-targeted therapeutic drug in NPC is warranted.

This work is funded by EBV research and NPC AoE grants of AKSC.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5445.

Abstract 4361: Role of Id1-induced IGF2 in autocrine/endocrine promotion of esophageal cancer tumorigenesis and metastasis

Esophageal cancer is the 7th leading cause of cancer death in Hong Kong. The disease is highly lethal (with a 5-year survival rate of ∼14%) because many cases go undetected until the disease is at an advanced stage. Understanding of the underlying mechanisms and the signaling pathways involved in esophageal tumorigenesis is the key to identify new molecular targets for intervention. Id1 (inhibitor of differentiation or DNA binding), a member of the helix-loop-helix (HLH) proteins, is overexpressed in many types of human cancer. Our previous reports provided the first evidence that Id1 activates the phosphatidylinositol-3-kinase (PI3K)/AKT pathway in esophageal squamous cell carcinoma (ESCC) cells, and that there is a positive correlation between Id1 and phosphorylated (p)-AKT expressions in clinical esophageal cancer specimens. We also demonstrated in experimental animal models that Id1 promotes tumor growth and metastasis through activation of PI3K/AKT. Increasing evidence suggests that growth factors secreted from cancer cells can play an important role in cancer progression by modulating the tumor microenvironment and the host systemic environment via autocrine, paracrine, and endocrine mechanisms. In this study, we found that Id1 induced the expression and secretion of IGF2 (insulin-like growth factor 2) in ESCC cells, and that this induction mediated the activation of PI3K/AKT in an autocrine manner. Knockdown of IGF2 in cancer cells or addition of IGF2 neutralizing antibody abrogated the effects of Id1 on proliferation, survival, and invasion of esophageal cancer cells. The mechanisms by which Id1 upregulates IGF2 were studied, and the results indicated that Id1 could protect IGF2 from ubiquitin-proteasomal degradation in ESCC cells. Immunohistochemical analysis of human esophageal cancer tissue microarray showed elevated IGF2 expression in ESCC, which correlated with increased Id1 and p-AKT expressions. Furthermore, our in vivo experiments showed that IGF2 secreted by Id1-overexpressing ESCC xenograft could instigate the growth of distant ESCC tumors, as well as promote metastasis of circulating ESCC cells. Targeting IGF2 with the use of neutralizing antibody had significant antitumor effects on esophageal cancer xenografts in mice. Our findings therefore support that the Id1-IGF2-PI3K/AKT signaling cascade plays an important role in esophageal cancer, and that Id1-overexpressing primary tumors may affect the host systemic environment and contribute to cancer progression. In conclusion, we have uncovered a novel mechanism in the role of Id1 in tumorigenesis which may have significant implications for the development of targeted therapy for esophageal cancer. [This study is supported by the Research Grants Council of the Hong Kong SAR, China (General Research Fund Project no. HKU 762610M)]

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4361. doi:1538-7445.AM2012-4361

Replication and pathogenesis of avian influenza A (H5N1) virus infection in polarised human bronchial and alveolar epithelium

1. In vitro models of polarised human respiratory epithelial cells were established to investigate the tropism and innate host responses of influenza A (H5N1 and H1N1) viruses. 2. Both viruses efficiently infected alveolar epithelial cells of both the apical and basolateral surfaces of the epithelium, whereas release of newly formed virus was mainly from the apical surface of the epithelium. 3. H5N1 virus was a more potent inducer of cytokines and chemokines in alveolar epithelial cells than H1N1 virus. Such chemokines were secreted onto both the apical and basolateral surfaces of the polarised alveolar epithelium. 4. In bronchial epithelium, the H5N1 virus replicated more efficiently and induced a stronger type I interferon response in the undifferentiated NHBE cells than did H1N1 virus. In contrast, in well-differentiated cultures, H5N1 virus replication was less efficient and elicited a lower interferon-beta response than did H1N1 virus. 5. Recombinant virus with vRNPs of a mammalian PB2 and an avian PB1 had the strongest polymerase activities, and replicated better in human cell cultures, especially at a high incubation temperature. These viruses were potent inducers of cytokines and chemokines in primary human alveolar epithelial cells.

Abstract 4784: Genetic alterations in premalignant nasopharyngeal epithelium support stable EBV infection

EBV infection is closely associated with nasopharyngeal carcinoma. Early events involved in the establishment of EBV infection in premalignant nasopharyngeal epithelium are largely undefined. We have established multiple immortalized nasopharygeal epithelial cells as premalignant cell models for EBV infection. We observed that nasopharyngeal epithelial cells immortalized by combined actions of telomerase and cyclin D1 or knocking down p16 could support stable EBV infection. Furthermore, we observed that EBV infection commonly induces growth inhibition and senescence in infected nasopharyngeal epithelial cells. Overexpression of cyclin D1 suppresses the growth inhibition and support EBV infection. Furthermore cyclin D1 expression confers resistance to differentiation induction in immortalized nasopharyngeal epithelial cells. EBV infection is closely associated with undifferentiated nasopharyngeal carcinoma. We observed that cyclin D1 overexpression is common in premalignant nasopharyngeal epithelium and co-exist with EBV infection shown by EBER staining. All these showed that cyclin D1 overexpression or suppression of the p16 activation support EBV infection establishment in premalignant nasopharyngeal epithelium which has been postulated to be an important and early event in NPC development.

Citation Format: George Sai-Wah Tsao, Anna CM Tsang, Elaine YL Yip, W Deng, Annie LM Cheung, KW Lo. Genetic alterations in premalignant nasopharyngeal epithelium support stable EBV infection. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4784. doi:10.1158/1538-7445.AM2013-4784

Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.

NADPH oxidase 5α promotes the formation of CD271 tumor-initiating cells in oral cancer

Oral tongue squamous cell carcinoma (OTSCC) has a distinctive cell sub-population known as tumor-initiating cells (TICs). CD271 is a functional TIC receptor in head and neck cancers. The molecular mechanisms governing CD271 up-regulation remains unclear. Oxidative stress is a contributing factor in TIC development. Here, we explored the potential role of NADPH oxidase 5 (NOX5) and its regulatory mechanism on the development of CD271-expressing OTSCC. Our results showed that the splice variant NOX5α is the most prevalent form expressed in head and neck cancers. NOX5α enhanced OTSCC proliferation, migration, and invasion. Overexpression of NOX5α increased the size of OTSCC xenograft significantly in vivo. The tumor-promoting functions of NOX5α were mediated through the reactive oxygen species (ROS)-generating property. NOX5α activated ERK singling and increased CD271 expression at the transcription level. Also, NOX5α reduces the sensitivity of OTSCC to cisplatin and natural killer cells. The findings indicate that NOX5α plays an important part in the development of TIC in OTSCC.

Abstract 2392: The role of ATM in lytic infection of EBV in nasopharyngeal epithelial cells

Epstein-Barr virus (EBV), a type of oncogenic herpesvirus, is associated with human malignancies. Previous studies have shown that reactivation of EBV in infected cells induces ATM-dependent DNA damage response (DDR). The functional role and involvement of ATM activation during lytic induction remains obscure. In this study, the essential role of ATM for viral DNA replication was examined in EBV-infected nasopharyngeal epithelial cells. Induction of lytic EBV infection triggers ATM activation and localization of DDR proteins at the viral replication compartments. Suppression of ATM activity using siRNA approach or specific chemical inhibitor diminished EBV DNA replication and production of infectious virion in EBV-infected cells induced to undergo lytic infection. Phosphorylation of Sp1 is a downstream event of ATM activation. The phosphorylation of Sp1 at serine 101 residue is crucial in promoting the accretion of EBV replication proteins at the replication compartment to facilitate viral DNA replication. Depletion of Sp1 suppresses viral DNA replication and localization of EBV replication proteins to the replication compartments. Our studies support an important role of ATM activation in lytic infection of EBV. Phosphorylation of Sp1 is an essential process mediating the recruitment of EBV replication protein to replication compartments. Our study highlights the importance of DDR pathway in lytic infection of EBV and suggests the potential application of specific DDR inhibitors to control the EBV replication in infected cells.

Funding support: Research Grant Council of Hong Kong (GRF #779312 & 779713; AoE/M-06/08).

Note: This abstract was not presented at the meeting.

Citation Format: George Sai-Wah Tsao, Pok Man Hau. The role of ATM in lytic infection of EBV in nasopharyngeal epithelial cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2392. doi:10.1158/1538-7445.AM2014-2392

Abstract 1108: M2-polarized macrophages increase invasiveness of EBV-associated nasopharyngeal carcinoma by inducing invadopodia formation

Cancer metastasis is a major cause of mortality, accounting for approximately 90% of cancer related deaths. Emerging evidences suggest that tumour microenvironment plays an indispensable role in cancer metastasis. Recruitment of innate and adaptive immune cells to the tumour results in chronic inflammation which favours tumour growth and progression. Particularly, tumour associated macrophages (TAMs) are found to promote the initiation, growth, and metastasis in several types of cancers. Nasopharyngeal carcinoma (NPC) is one of the highly invasive and metastatic cancers and is closely associated with EBV infection. We postulate that TAMs may increase the invasiveness of NPC by enhancing the formation of invadopodia, which are membranous actin-rich protrusions with digestive ability of extra-cellular matrix. In this study, monocyte THP-1 cells were polarized to M2-macrophages, and co-cultured with nasopharyngeal cells in a contained chamber-insert. The stimulated nasopharyngeal cells then formed massive numbers of invadopodia and digested larger area of gelatin compared with the unstimulated counterparts. A cytokine antibody array was used to identify the upregulated cytokines in the co-culture medium of the M2-macrohphages and the NPC cells. Tumour necrosis factor alpha (TNFα) was revealed to be the responsible cytokine to induce the formation of invadopodia and digestion of gelatin. Besides, western blot analysis identified that several actin-associated proteins such as Src, Erk, and cortactin were involved in the TNFα-mediated invadopodia formation. We also found that the expression of latent membrane protein 1 (LMP1), an EBV protein that has similar structure to TNF receptor was elevated in NPC cells after co-culturing with the M2-polarized macrophages. Through transient transfection and stable expression of LMP1 in the NPC cells, LMP1 could also promote the formation of invadopodia through cdc42 activation. Taken together, these data indicate macrophages can promote the invasiveness of EBV-infected NPC cells by enhancing their ability in forming invadopodia through an activated TNFα signaling axis and LMP1 upregulation.

Citation Format: Wilson Wing Chung Tang, Chan Ping You, Gareth E. Jones, George Sai-Wah Tsao, Anna Chi Man Tsang. M2-polarized macrophages increase invasiveness of EBV-associated nasopharyngeal carcinoma by inducing invadopodia formation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1108.

Abstract 2462: Epstein-Barr virus-encoded microRNAs regulate the expression of BRCA1 in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is an aggressive epithelial malignancy and is endemic in southern China and Southeast Asia. It is well-known to be associated with Epstein-Barr virus (EBV) infection. The miRNAs derived from EBV BamH1-A rightward transcripts (miR-BARTs) are abundantly expressed in NPC and have been suggested that can contribute to cancer development by regulating several gene expression. In this study, we established comprehensive expression profile of miRNAs in an EBV positive NPC cell line and 5 xenografts by small RNA sequencing. By using the prediction algorithm of miRanda and RNAhybrid, in silico analysis identified that several abundantly expressed miRNAs from viral and cellular genomes could negatively regulate BRCA1 expression via the 3' untranslated region (3'UTR). Notably, the regulatory role of miR-BART17-5p, miR-BART19-3p, miR182-5p on endogenous BRCA1 expression was demonstrated by transient transfection assays in HeLa cells and the direct recognitions were verified by luciferase reporter assays, while the downregulation of BRCA1 in primary NPCs was substantiated in the immunohistochemical (IHC) staining in a cohort of 61 histologically normal nasopharyngeal (NP) and 37 primary NPC cases (p<0.001). Taken togethher, we showed that the highly expressed miRNAs could work co-operatively to modulate BRCA1 activity. It has been reported that BRCA1 deficient tumor cells are defective in repairing the DNA double-strand breaks (DSBs) via error-free homologous recombination (HR). The impaired DSB repair by EBV latent infection may induce genome instability during NPC tumorigenesis and also contribute to sensitizing the tumor cells to ionizing radiation and DNA-damaging agent treatments.

Acknowledgement:

Theme-based Research Scheme (T12-401/13-R) and GRF (14104415, 14138016), Research Grant Council, Hong Kong

Citation Format: Ka-Hei Lam, Raymond Wai-Ming Lung, Pok-Man Hau, Kevin Yuk-Lap Yip, George Sai-Wah Tsao, Ken Hung-On Yu, Joanna Hung-Man Tong, Kwok-Wai Lo, Ka-Fai To. Epstein-Barr virus-encoded microRNAs regulate the expression of BRCA1 in nasopharyngeal carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2462.