Sonic Hedgehog Pathway (HHIP, PTCH1 and SHH) VEGF-A in Oral Squamous Cell Carcinomas: Association with Expression of VEGF-A and Microvessels
Caroline Brandi Schlaepfer-Sales, Marcilei Eliza Cavichiolli Buim, Renata Oliveira Souza, Ludmila Faro Valverde, Maria Cecilia Mathias Machado, Jean Nunes Dos Santos, Mitermayer Galvao Reis, Fernando Augusto Soares, Eduardo Antonio Goncalves Ramos, Clarissa Araujo Gurgel. Federal University of Bahia, Salvador, Bahia, Brazil; Oswaldo Cruz Foundation-Gonçalo Moniz Research Center, Salvador, Bahia, Brazil; AC Camargo Hospital, São Paulo, Brazil
Background: Sonic Hedgehog (SHH) signaling has been implicated in tumor development and progression by stimulating angiogenesis and its molecular mechanisms are little known in oral squamous cell carcinomas (OSCC). The aim of this study was to characterize the transcripts expression involved in the SHH pathway (SHH, PTCH1, HHIP, VEGF-A) and microvessel density OSCC.
Design: A total of 50 OSCC, eight non-tumor epithelium adjacent to oral cancer (NTEA), and two oral mucosa obtained from healthy individuals were included. After RNA extraction, complementary DNA was obtained using high-capacity transcriptase. Quantitative PCR reactions were using Taqman Gene Expression Assays (SHH, PTCH1, HHIP and VEGF-A). Cq (ΔΔCQ) relative quantification method was perfomed for gene expression analysis. Fifty six paraffin-embedded specimens of OSCC were used for tissue microarray (TMA) and by immunohistochemistry, VEGF and CD34 were studied.
Results: HHIP and PTCH1 transcripts were detected in OSCC and NTEA. Seventeen (34%) OSCC cases were negative for SHH gene expression. POSITIVE correlation between SHH and HHIP (rs=0.29; p=0.044, Spearman test) and SHH and PTCH1 (rs=0.49; p=0.0003, Spearman test), SHH and VEGF-A (rs=0.37; p=0.0086; Spearman test) gene expression were observed in OSCC. Higher levels of VEGF-A expression seemed to increase the microvessel density of OSCC (rs=0.55;p=0.0050; Sperman test). Higher levels of transcripts and VEGF-A protein were related to OSCC with perineural invasion and those moderately differentiated. Finally, increased expression of VEGF-A was detected in NTEA (p = 0.034, Mann Whitney test).
Conclusions: THE positive correlation between the gene expression of SHH and VEGF-A indicates that pathway SHH could participate in tumor angiogenesis, and VEGF-A gene expression was the only factor that contributed to a greater MVD in our series. In addition, increased expression of this gene and protein VEGF-A was related to more aggressive behavior of OSCC. The expression of HHIP, PTCH1 and VEGF-A in NTEA also indicates that SHH pathway can be activated in the tumor margins and might suggest existence of a field cancerization. At the same time, increased gene expression of VEGF-A in this location suggests that adjacent cells to oral cancer could actively participate in the secretion of important growth factors to the tumor development.
Category: Head & Neck
Wednesday, March 6, 2013 9:30 AM
Poster Session V # 211, Wednesday Morning