Abstract 786: Alterations of TGFβ/Smad signaling in human head and neck squamous cell carcinomas
Authors: Reiss Michael , Xie Wen , Chen Wenjin , Foran David , Aisner Seena , Baredes Soly 
Published: February 2011

Head-and-neck squamous cell carcinoma (HNSCC) ranks as the sixth most frequent cancer worldwide. Based on earlier in vitro studies of HNSCC cell lines and genetic analysis of human HNSCC specimens, we postulated that disruptions of Transforming Growth Factor- β (TGF-β) signaling contribute to the development and progression of HNSCC. Smad proteins are the intracellular components of the TGF-β signaling pathway. In a previous immunohistochemical study of the expression and activation of Smads in 170 HNSCC specimens assembled in a tissue microarray, phospho-Smad2 (pSmad2), an active form of Smad2 and Smad4 were absent in 14% and 22% of cases respectively. Moreover, there was a trend towards improved overall survival (OS) among patients with pSmad2-negative tumors. In the present study, we analyzed the pattern of expression of (p)Smad2, (p)Smad3 and Smad4 in a much larger 4-fold redundant tissue array of 798 HNSCC tumor samples obtained from 346 patients. In addition, we compared a new automated scoring method to standard visual scoring of immunostained slides. Each tissue core was visually scored as positive or negative, and the four scores averaged to derive a visual score (VS). Automated scores (AS) were obtained by scanning all slides using a Zeiss MedMicro whole slide scanner at 40×equivalent resolution. Images of individual cores were extracted from the scanned archive and staining maps of chromogen (brown) were isolated from the counter stain using our previously reported color decomposition algorithm. AS was computed based on the staining characteristic of each core and a final score for each specimen was obtained by averaging the scores of four matched cores. Receiver operating characteristic (ROC) curves demonstrated that the AS scoring method performed extremely well compared the VS “gold standard”, with area under the curve (AUC) values of &gt;80% for all 5 Smad immunostains.

We found that 19% (95% CI: 16-21%), 40% (95% CI: 36-43%) and 12% (95% CI: 10-15%) of HNSCC specimens failed to express pSmad2, pSmad3 or Smad4, respectively. Loss of TGF-β receptor signaling, as indicated by both pSmad2 and −3 negativity, was observed in 11% (95% CI: 9-13%) of specimens. In addition, 10% (95% CI: 8-12%) of specimens failed to express Smad4. These results are consistent with our previous findings in a smaller sample set. Moreover, among 198 patients with survival information, patients with pSmad2/3 negative tumors had a significantly higher OS when compared with patients with pSmad2/3 positive tumors (p=0.0090). In contrast, loss of Smad4 expression was not associated with poor survival. These results indicate that inactivation of TGF-β receptor signaling or of Smad4 in HNSCC have different clinical implications and may reflect underlying differences in biological significance.

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 786.