Chromosome 17 In Situ Hybridization Grid-based Analysis in Oral Squamous Cell Carcinoma

Background/aim: Oral squamous cell carcinoma (OSCC) is an aggressive malignancy due to its increased ability for local metastases and distant lymph node metastases. Extensive cytogenetic analyses have detected chromosome instability (CI) patterns in OSCC including gross chromosome numerical alterations, such as polysomy and sporadically monosomy that negatively affect the biological behaviour of the malignancy. Our aim was to investigate the frequency and impact of chromosome 17 (Chr 17) numerical imbalances in OSCC.

Materials and methods: Fifty (n=50) formalin-fixed, paraffin-embedded primary OSCCs tissue sections were used. Chromogenic in situ hybridization (CISH) was implemented for detecting Chr 17 centromeric numerical imbalances. Concerning the screening process in CISH slides, a novel real-time reference and calibration grid platform was implemented.

Results: Chr 17 multiple copies were observed in 12/50 (24%) of the examined cases. Polysomy was observed in 10/50 (20%) tissue sections, monosomy in 2/50 (4%), whereas the rest of them demonstrated a normal, diploid pattern (38/50-76%). Chr 17 numerical differences were associated with the grade of differentiation of the examined tumors (p=0.001).

Conclusion: Chr 17 numerical imbalances (polysomy predominantly and monosomy) are observed in sub-groups of OSCCs correlating with a progressive dedifferentiation of malignant tissues. The proposed grid-based platform on CISH slides provides a novel, fast and accurate screening-mapping mechanism for detecting chromosome numerical aberrations.