Clinical Implications of FADD Gene Amplification and Protein Overexpression in Taiwanese Oral Cavity Squamous Cell Carcinomas

<div><p>Amplification of 11q13.3 is a frequent event in human cancers, including head and neck squamous cell carcinoma. This chromosome region contains several genes that are potentially cancer drivers, including <i>FADD</i> (Fas associated via death domain), an apoptotic effector that was previously identified as a novel oncogene in laryngeal/pharyngeal cancer. This study was designed to explore the role of FADD in oral squamous cell carcinomas (OSCCs) samples from Taiwanese patients, by assessing copy number variations (CNVs) and protein expression and the clinical implications of these factors in 339 male OSCCs. The intensity of FADD protein expression, as determined by immunohistochemistry, was strongly correlated with gene copy number amplification, as analyzed using a TaqMan CNV assay. Both FADD gene copy number amplification and high protein expression were significantly associated with lymph node metastasis (<i>P</i> < 0.001). Patients with both FADD copy number amplification and high protein expression had the shortest disease-free survival (DFS; <i>P</i> = 0.074 and <i>P</i> = 0.002) and overall survival (OS; <i>P</i> = 0.011 and <i>P</i> = 0.027). After adjusting for primary tumor status, tumor differentiation, lymph node metastasis and age at diagnosis, DFS was still significantly lower in patients with either copy number amplification or high protein expression (hazard ratio [H.R.] = 1.483; 95% confidence interval [C.I.], 1.044–2.106). In conclusion, our data reveal that FADD gene copy number and protein expression can be considered potential prognostic markers and are closely associated with lymph node metastasis in patients with OSCC in Taiwan.</p></div

Immunohistochemical comparison of FADD expression.

<p>FADD protein expression in three OSCC patients and normal epithelium. (A), Normal epithelium showing weak cytoplasmic and nuclear staining as a reference. (B), Representative staining pattern of FADD 1+. (C), FADD 2+. (D) FADD 3+.</p

Survival curves based on analysis of the Fas-associated death domain (FADD) gene CNA.

<p>(A) Kaplan-Meier curves for disease-free survival (DFS).(B) Kaplan-Meier curves for overall survival (OS).</p

Characteristics of the 339 OSCC patients.

<p>Characteristics of the 339 OSCC patients.</p

Univariate Cox regression model of prognostic covariates in 339 patients with OSCC: disease-free and overall survival.

<p>Univariate Cox regression model of prognostic covariates in 339 patients with OSCC: disease-free and overall survival.</p

Survival curves based on analysis of Fas-associated death domain (FADD) protein expression.

<p>(A) Kaplan-Meier curves for disease-free survival (DFS).(B) Kaplan-Meier curves for overall survival (OS).</p

Immunohistochemical comparison of FADD expression.

<p>FADD protein expression in three OSCC patients and normal epithelium. (A), Normal epithelium showing weak cytoplasmic and nuclear staining as a reference. (B), Representative staining pattern of FADD 1+. (C), FADD 2+. (D) FADD 3+.</p

Additional file 1: of EGFR copy number alterations in primary tumors, metastatic lymph nodes, and recurrent and multiple primary tumors in oral cavity squamous cell carcinoma

Questionnaire for OSCC patients. The questionnaire used in this study includes detailed information on general demographic data, current and past cigarette smoking, alcohol consumption, areca-quid (AQ) chewing, and a history of family disease. (DOCX 35 kb

Survival curves based on combined Fas-associated death domain (FADD) gene CNA and protein expression analysis.

<p>(A) Kaplan-Meier curves for disease-free survival (DFS).(B) Kaplan-Meier curves for overall survival (OS).</p

Thyroid hormone suppresses hepatocarcinogenesis via DAPK2 and SQSTM1-dependent selective autophagy

<p>Recent studies have demonstrated a critical association between disruption of cellular thyroid hormone (TH) signaling and the incidence of hepatocellular carcinoma (HCC), but the underlying mechanisms remain largely elusive. Here, we showed that disruption of TH production results in a marked increase in progression of diethylnitrosamine (DEN)-induced HCC in a murine model, and conversely, TH administration suppresses the carcinogenic process via activation of autophagy. Inhibition of autophagy via treatment with chloroquine (CQ) or knockdown of ATG7 (autophagy-related 7) via adeno-associated virus (AAV) vectors, suppressed the protective effects of TH against DEN-induced hepatic damage and development of HCC. The involvement of autophagy in TH-mediated protection was further supported by data showing transcriptional activation of DAPK2 (death-associated protein kinase 2; a serine/threonine protein kinase), which enhanced the phosphorylation of SQSTM1/p62 (sequestosome 1) to promote selective autophagic clearance of protein aggregates. Ectopic expression of DAPK2 further attenuated DEN-induced hepatoxicity and DNA damage though enhanced autophagy, whereas, knockdown of DAPK2 displayed the opposite effect. The pathological significance of the TH-mediated hepatoprotective effect by DAPK2 was confirmed by the concomitant decrease in the expression of THRs and DAPK2 in matched HCC tumor tissues. Taken together, these findings indicate that TH promotes selective autophagy via induction of DAPK2-SQSTM1 cascade, which in turn protects hepatocytes from DEN-induced hepatotoxicity or carcinogenesis.</p