Jimmy Yu-Wai Chan

Active Replication of Middle East Respiratory Syndrome Coronavirus and Aberrant Induction of Inflammatory Cytokines and Chemokines in Human Macrophages: Implications for Pathogenesis

Abstract Middle East respiratory syndrome coronavirus (MERS-CoV) infection caused severe pneumonia and multiorgan dysfunction and had a higher crude fatality rate (around 50% vs 10%) than SARS coronavirus (SARS-CoV) infection. To understand the pathogenesis, we studied viral replication, cytokine/chemokine response, and antigen presentation in MERS-CoV–infected human monocyte–derived macrophages (MDMs) versus SARS-CoV–infected MDMs. Only MERS-CoV can replicate in MDMs. Both viruses were unable to significantly stimulate the expression of antiviral cytokines (interferon α [IFN-α] and IFN-β) but induced comparable levels of tumor necrosis factor α and interleukin 6. Notably, MERS-CoV induced significantly higher expression levels of interleukin 12, IFN-γ, and chemokines (IP-10/CXCL-10, MCP-1/CCL-2, MIP-1α/CCL-3, RANTES/CCL-5, and interleukin 8) than SARS-CoV. The expression of major histocompatibility complex class I and costimulatory molecules were significantly higher in MERS-CoV–infected MDMs than in SARS-CoV–infected cells. MERS-CoV replication was validated by immunostaining of infected MDMs and ex vivo lung tissue. We conclusively showed that MERS-CoV can establish a productive infection in human macrophages. The aberrant induction of inflammatory cytokines/chemokines could be important in the disease pathogenesis.

MicroRNA let-7 suppresses nasopharyngeal carcinoma cells proliferation through downregulating c-Myc expression

AimsThis study aimed at evaluating the potential anti-proliferative effects of the microRNA let-7 family in nasopharyngeal carcinoma (NPC) cells. In addition, the association between let-7 suppression and DNA hypermethylation is examined.Materials and methodsLevels of mature let-7 family members (-a, -b, -d, -e, -g, and -i) in normal nasopharyngeal cells (NP69 and NP460) and nasopharyngeal carcinoma cells (HK1 and HONE1) were measured by real-time quantitative PCR. Cell-proliferation assay and c-Myc immunohistochemical staining were performed on NPC cells transfected with let-7 precursor molecules. In addition, expression changes in let-7 family members in response to demethylating agents (5-azacytidine and zebularine) were also examined.ResultsIn comparison with the normal nasopharyngeal cells, let-7 (-a, -b, -d, -e, -g, and -i) levels were reduced in nasopharyngeal carcinoma cells. Ectopic expression of the let-7 family in nasopharyngeal carcinoma cells resulted in inhibition of cell proliferation through downregulation of c-Myc expression. Demethylation treatment of nasopharyngeal carcinoma cells caused activation of let-7 expression in poorly differentiated nasopharyngeal carcinoma cells only.ConclusionOur results suggested that miRNA let-7 might play a role in the proliferation of NPC. DNA methylation is a potential regulatory pathway, which is affected when let-7 is suppressed in NPC cells. However, the extent of DNA hypermethylation/hypomethylation in regulating let-7 expression requires further elucidation.

Surgical salvage of persistent or recurrent nasopharyngeal carcinoma with maxillary swing approach — Critical appraisal after 2 decades

The purpose of this study was to report on our experience on salvage nasopharyngectomy using the maxillary swing approach for persistent or recurrent nasopharyngeal carcinoma after primary treatment.

IL‐1β Promotes Malignant Transformation and Tumor Aggressiveness in Oral Cancer

Chronic inflammation, coupled with alcohol, betel quid, and cigarette consumption, is associated with oral squamous cell carcinoma (OSCC). Interleukin‐1 beta (IL‐1β) is a critical mediator of chronic inflammation and implicated in many cancers. In this study, we showed that increased pro‐IL‐1β expression was associated with the severity of oral malignant transformation in a mouse OSCC model induced by 4‐Nitroquinolin‐1‐oxide (4‐NQO) and arecoline, two carcinogens related to tobacco and betel quid, respectively. Using microarray and quantitative PCR assay, we showed that pro‐IL‐1β was upregulated in human OSCC tumors associated with tobacco and betel quid consumption. In a human OSCC cell line TW2.6, we demonstrated nicotine‐derived nitrosamine ketone (NNK) and arecoline stimulated IL‐1β secretion in an inflammasome‐dependent manner. IL‐1β treatment significantly increased the proliferation and dysregulated the Akt signaling pathways of dysplastic oral keratinocytes (DOKs). Using cytokine antibodies and inflammation cytometric bead arrays, we found that DOK and OSCC cells secreted high levels of IL‐6, IL‐8, and growth‐regulated oncogene‐α following IL‐1β stimulation. The conditioned medium of IL‐1β‐treated OSCC cells exerted significant proangiogenic effects. Crucially, IL‐1β increased the invasiveness of OSCC cells through the epithelial‐mesenchymal transition (EMT), characterized by downregulation of E‐cadherin, upregulation of Snail, Slug, and Vimentin, and alterations in morphology. These findings provide novel insights into the mechanism underlying OSCC tumorigenesis. Our study suggested that IL‐1β can be induced by tobacco and betel quid‐related carcinogens, and participates in the early and late stages of oral carcinogenesis by increasing the proliferation of dysplasia oral cells, stimulating oncogenic cytokines, and promoting aggressiveness of OSCC. J. Cell. Physiol. 230: 875–884, 2015.

Mature miR-184 and Squamous Cell Carcinoma of the Tongue

Human microRNA 184 (miR-184) is overexpressed in squamous cell carcinoma (SCC) of the tongue. In vitro inhibition of miR-184 levels could induce apoptosis and hinder proliferation of tongue SCC cells. Patients with tongue SCC have high plasma miR-184 levels. Plasma miR-184 is likely associated with the tumor load. Surgical removal of the primary tumor reduced plasma miR-184 levels significantly. The data suggested that miR-184 is linked to the pathogenesis of tongue SCC. Further studies are warranted to evaluate the use of microRNA-based serological markers in monitoring tongue SCC.

Nasopharyngectomy for locally advanced recurrent nasopharyngeal carcinoma: Exploring the limits

The purpose of this study was to present the outcome of nasopharyngectomy for locally advanced recurrent nasopharyngeal carcinoma (NPC).

Extramammary Paget’s Disease: 20 Years of Experience in Chinese Population

Background. To examine the results of treatment of Extramammary Pagets disease (EMPD) in ethnic Chinese. Method. Between 1990 and 2010, patients treated for EMPD were reviewed. Data were analyzed retrospectively. Results. Forty-eight patients were treated by surgical resection. Local recurrence rate was 14.6%. The postresection defects were repaired by primary closure (8.3%), partial thickness skin graft (72.9%), or local/regional flaps (18.8%). Dermal invasion was found in 9 patients (18.8%). Seven patients (14.6%) developed regional lymph node metastasis (concurrent with surgery, n = 1; subsequent to surgery, n = 6), and 3 patients (6.3%) had systemic metastasis after surgery. The presence of dermal invasion was associated with significantly higher incidence of regional lymph nodes and systemic metastasis. The incidence of associated internal malignancy was 8.3%. Conclusion. The mainstay of treatment for EMPD is surgery. Pathological dermal invasion increases the chance of regional lymph node as well as systemic metastasis. The association with internal malignancy warrants preoperative endoscopic examination in all patients.

Epigenetic regulation of the X-linked tumour suppressors BEX1 and LDOC1 in oral squamous cell carcinoma.

The strong associations between oral squamous cell carcinoma (OSCC) and dietary habits such as alcohol consumption (A), betel quid chewing (B) and cigarette smoking (C) and its predominance in men have been well documented; however, systemic analysis of OSCC is limited. Our study applied high‐throughput screening methods to identify causative epigenetic targets in a cohort of men with ABC‐associated OSCC. We identified BEX1 and LDOC1 as two epigenetically silenced X‐linked tumour suppressors and demonstrated a functional link between the transcription of BEX1 and LDOC1 and promoter hypermethylation. Methylation of the BEX1 and LDOC1 promoters was associated significantly (p < 0.0001) with OSCC and were detected in 75% (42/56) and 89% (50/56) of the samples, respectively. We observed concordant increases in the methylation of both genes in 71% (40/56) of the tumours, and potent in vitro and in vivo growth inhibitory effects in OSCC cells ectopically expressing BEX1 and/or LDOC1. Restored expression of BEX1 and LDOC1 suppressed the nuclear factor‐κB (NF‐κB) signalling pathway, which is the most frequently hyperactivated signalling pathway in OSCC. This suppression might result from decreased p50 and p65 expression. These findings suggest that silencing of BEX1 and LDOC1 by promoter hypermethylation might represent a critical event in the molecular pathogenesis of OSCC and account for the oncogenic effects of ABC exposure and the male predominance of OSCC occurrence. Microarray data are available in the Gene Expression Omnibus (GEO; http://www.ncbi.nlm.nih.gov/geo/) Copyright

Critical appraisal of maxillary swing approach for nasopharyngeal carcinoma

Background: The aim of the current study was to report results of salvage nasopharyngectomy using the maxillary swing approach for persistent or recurrent nasopharyngeal carcinoma after primary treatment. Methods: Between 1989 and 2011, Nasopharyngectomies were performed in 312 patients. Data were composed of retrospective review of records of the first 72 patients followed by a prospective collection of data for the remaining patients. Results: Among the patients, 41 (13.1%) had persistent tumours and 271 (86.9%) had recurrent disease. Curative resection was achieved in 248 (79.5%) patients. All patients survived the operations. The median follow up duration was 34 months. The overall 5-year actuarial local tumour control was 74% and the overall 5-year disease-free survival was 56%. Those with negative resection margins on frozen section and tumour size less than 1.5 cm in diameter had significantly better local tumour control in the nasopharynx as well as disease-free survival. Conclusions: Maxillary swing nasopharyngectomy is an effective salvage procedure for small, persistent or recurrent tumour in the nasopharynx after primary therapy.

Long Non-Coding RNA Deregulation in Tongue Squamous Cell Carcinoma

Background. The deregulated tumorigenic long non-coding RNA (lncRNA) has been reported in several malignancies. However, there is still no comprehensive study on tongue squamous cell carcinoma (SCC). Methods. Functional reannotation for the human lncRNA was carried out by ncFANs. Real-time quantitative PCR was used to validate the identified lncRNAs. Results. Using the functional annotation algorithm from ncFANs, 8 differentially expressed lncRNAs were identified. Lnc-PPP2R4-5, lnc-SPRR2D-1, lnc-MAN1A2-1, lnc-FAM46A-1, lnc-MBL2-4:1, and lnc-MBL2-4:3 were upregulated in the microdissected tongue SCC tissues. In comparison, lnc-AL355149.1-1 and lnc-STXBP5-1 showed significant downregulation. High level of lnc-MBL2-4:3 was significantly associated with the node positive tongue SCC patients. Further, patients with advanced T-stage demonstrated a further reduction of lnc-AL355149.1-1 in the tumor tissues. Treatment of tongue SCC cells with 5-fluorouracil and paclitaxel can reserve the expression patterns observed in the tongue SCC tissues. Further, changes of lnc-MBL2-4:3 and lnc-AL355149.1-1 expression levels were noticed in the cisplatin-resistant tongue SCC cells. Conclusions. Our results demonstrated that functional reannotation allows us to identify novel lncRNAs using the existing gene expression array dataset. The association of lncRNA with the T-stage and nodal status of tongue SCC patients suggested that lncRNA deregulation was involved in the pathogenesis of tongue SCC.