Genetic polymorphisms in the prostaglandin pathway genes and risk of head and neck cancer.

OBJECTIVE: Previous studies examining the association between genetic variations in prostaglandin pathway and risk of head and neck cancer (HNC) have only included polymorphisms in the PTGS2 (COX2) gene. This study investigated the association between genetic polymorphisms of six prostaglandin pathway genes (PGDS, PTGDS, PTGES, PTGIS, PTGS1 and PTGS2), and risk of HNC. METHODS: Interviews regarding the consumption of alcohol, betel quid, and cigarette were conducted with 222 HNC cases and 214 controls. Genotyping was performed for 48 tag and functional single-nucleotide polymorphisms (SNPs). RESULTS: Two tag SNPs of PTGIS showed a significant association with HNC risk [rs522962: log-additive odds ratio (OR) = 1.42, 95% confidence interval (CI): 1.01-1.99 and dominant OR = 1.58, 95% CI: 1.02-2.47; rs6125671: log-additive OR = 1.49, 95% CI: 1.08-2.05 and dominant OR = 1.96, 95% CI: 1.16-3.32]. In addition, a region in PTGIS tagged by rs927068 and rs6019902 was significantly associated with risk of HNC (global P = 0.007). Finally, several SNPs interacted with betel quid and cigarette to influence the risk of HNC. CONCLUSIONS: Genetic variations in prostaglandin pathway genes are associated with risk of HNC and may modify the relationship between use of betel quid or cigarette and development of HNC.

Apoptotic mechanism of paclitaxel-induced cell death in human head and neck tumor cell lines.

BACKGROUND: Paclitaxel (taxol) is clinically used to treat various human tumors. However, the cellular and molecular mechanism regarding apoptotic effect of paclitaxel on head and neck squamous cell carcinoma (HNSCC) remains elusive. METHODS: The apoptotic effect and the mechanism of paclitaxel on FaDu hypopharyngeal cancer cell line, OEC-M1 gingival cancer cell line, and OC3 betel quid chewing-related buccal cancer cell lines were investigated by morphological observations, cell viability assay, flow cytometry assay and Western blotting methods. RESULTS: Rounded-up cell number increased with membrane blebbing as the treatment of paclitaxel (50-500 nM) increased from 24 to 48 h among these cell lines. In cell viability assay, cell surviving rate significantly decreased from 87 to 27% as the dosage and duration of paclitaxel treatment increased (P < 0.05). Flow-cytometry analysis further demonstrated that 50 nM paclitaxel induced G2/M phase cell arrest among these cell lines within 8 h treatment, and then G2/M phase cell fraction significantly decreased as subG1 phase cell fraction significantly increased after 24 h treatment (P < 0.05), suggesting that cells underwent apoptosis. Furthermore, the activated caspases-8, -9, -3, -6 and poly ADP-ribose polymerase cleavage could all be significantly detected in FaDu, OEC-M1 and OC3 cells (P < 0.05). CONCLUSION: Paclitaxel activated cell cycle arrest and caspase protein expressions to induce apoptosis in HNSCC cell lines.

Tumour cell-derived WNT5B modulates in vitro lymphangiogenesis via induction of partial endothelial-mesenchymal transition of lymphatic endothelial cells.

Metastasis of the cervical lymph nodes frequently leads to poor survival of patients with oral squamous cell carcinoma (OSCC). The underlying mechanisms of lymph node metastasis are unclear. Wingless-type MMTV integration site family, member 5B (WNT5B), one component of the WNT signal pathway, was markedly up-regulated in OSCC sublines with high potential of lymphatic metastasis compared to that in OSCC cells with low nodal metastasis. Increased WNT5B mRNA was demonstrated in human OSCC tissues in comparison with adjacent non-tumorous tissues. Interestingly, the high level of WNT5B protein in serum was associated with lymph node metastasis in OSCC patients. Knockdown of WNT5B expression in OSCC sublines did not affect tumour growth but impaired lymph node metastasis and tumour lymphangiogenesis of orthotopic transplantation. Conditioned medium from WNT5B knockdown cells reduced the tube formation of lymphatic endothelial cells (LECs). In contrast, recombinant WNT5B enhanced the tube formation, permeability and migration of LECs. In LECs stained with phalloidin, the morphology of those treated with recombinant WNT5B changed from flat to spindle-like. Recombinant WNT5B also increased α-smooth muscle actin and inhibited the expression of vascular endothelial-cadherin but retained characteristics of endothelial cells. The results suggest that WNT5B functions in the partial endothelial-mesenchymal transition (EndoMT). Furthermore, WNT5B-induced tube formation was impaired in the LECs following the knockdown of EndoMT-related transcription factor, SNAIL or SLUG. The WNT5B-induced expression of Snail or Slug was abolished by IWR-1-endo and Rac1 inhibitors, which are involved in the WNT/ß-catenin and planar cell polarity pathways, respectively. Collectively, the data suggest that WNT5B induces tube formation by regulating the expression of Snail and Slug proteins through activation of canonical and non-canonical WNT signalling pathways.

EBER1 in situ hybridization as an adjuvant for diagnosis of recurrent nasopharyngeal carcinoma.

The mainstay treatment of nasopharyngeal carcinoma (NPC) is radiotherapy. Although NPC is a radiosensitive tumor, 25% of NPC patients still suffered from local relapse in Taiwan. Whether the pathologic changes induced by radiation have impact on the interpretation of suspicious recurrent NPC specimens is seldom mentioned. We retrospectively analyzed 20 irradiated NPC patients who were suspected to have local recurrence and received serial nasopharyngeal biopsies. A total of 31 nasopharyngeal tissues including 15 local recurrent specimens and 16 negative specimens were entered into this study. Compared with non-irradiated nasopharyngeal tissue, the irradiated nasopharynx showed fibrosis and areas of necrosis mixed with acute or chronic inflammation. Stroma cells were enlarged, with prominent nuclei and cytoplasm, and some bizarre cells might be confused with tumor cells. These post-irradiation effects did have an impact on histological interpretation. In this study, 2 out of 16 nasopharyngeal tissues were misdiagnosed as having no recurrent tumor by using H and E stain only. However, scattered cancer cells can be clearly visualized by using EBER1 in situ hybridization. Therefore, it is recommended that EBER1 in situ hybridization is routinely used in irradiated nasopharyngeal tissues in helping the diagnosis of recurrent NPC.

Epstein-Barr virus detection in neck metastases by in-situ hybridization in fine-needle aspiration cytologic studies: an aid for differentiating the primary site.

BACKGROUND: Nasopharyngeal carcinoma (NPC) is strongly associated with Epstein-Barr virus (EBV). The metastasis to cervical lymph nodes represents a frequent initial manifestation of NPC. The usefulness of EBV detection by polymerase chain reaction (PCR) in the diagnosis of occult NPC with cervical metastasis has been reported. Our previous study showed that EBER1 in-situ hybridization was somewhat more sensitive and specific than PCR in detecting EBV in the evaluation of specimens from a population at high risk for NPC. METHODS: Fine-needle aspiration cytologic specimens of neck masses from 30 patients were investigated, including 10 NPC primary tumors, 19 squamous cell carcinomas from other sites of the head and neck (9 oral cavity, 2 paranasal sinuses, 2 oropharynx, 3 larynx, and 3 hypopharynx), and 1 diffuse large-cell lymphoma. EBER1 in-situ hybridization was performed on direct smears made from aspirates. RESULTS: EBER1 signals were detected in all neck metastases from the nasopharynx but none of the specimens from other primary sites. CONCLUSIONS: This study suggests that EBER1 in-situ hybridization can be used as a supplemental tool for differential diagnosis whenever fine-needle aspiration cytologic examination is presented with a neck metastasis without knowing the primary site.

Constitutive activation of STAT3 and STAT5 is present in the majority of nasopharyngeal carcinoma and correlates with better prognosis.

Constitutively activated signal transducers and activators of transcription (STAT) factors, in particular STAT1, STAT3 and STAT5, have been demonstrated in a variety of human tumours and cancer cell lines. However, data on the expression of these STATs in nasopharyngeal carcinoma (NPC) are limited. In this study, the expression patterns of STAT1, STAT3 and STAT5 were immunohistochemically examined on the archival specimens from 61 patients with NPC. Staining results of each STATs were then correlated with the clinical parameters and prognosis of these patients. The results showed that constitutive activation of STAT3 and STAT5 was detected in the majority, 70.5 and 62.3%, respectively, of the 61 tumour specimens. Furthermore, coexpression of activated STAT3 and STAT5 was found in 54.1% of the specimens. In contrast, constitutive activated STAT1 could only be detected in 8 (13.1%) cases. Surprisingly, following radiotherapy, patients with constitutive STAT5 activation, or activation of both STAT3 and STAT5, had better disease-free survival and overall survival than those without activated STAT5. To our knowledge, this is the first report providing the overall expression patterns and prognostic significance of specific STATs in NPC.