González M V, Pello M F, Ablanedo P, Suárez C, Alvarez V, Coto E
Hospital Central de Asturias, Laboratorio de Genética Molecular, Oviedo, Spain.
J Clin Pathol. 1998 Jul;51(7):520-4. doi: 10.1136/jcp.51.7.520.
To study the loss of heterozygosity at the short arm of chromosome 3 in primary tumours from patients with squamous cell carcinoma of the head and neck; to determine whether the FHIT gene, mapped to 3p14.2 and the CTNNB1 (beta-cat) gene, mapped to 3p21, are deleted or mutated in these tumours.
DNA was extracted from fresh tumours. Loss of heterozygosity was assessed by microsatellite analysis of the following markers: D3S1283 and D3S1286 (3p24), D3S966 (3p21), and D3S1300 (3P14.2). Homozygous deletion was determined by radioactive multiplex polymerase chain reaction of exons 5 and 6 of the FHIT gene. The presence of mutations in FHIT exon 5 and beta-cat exon 3 was studied by single strand conformation polymorphism.
50% of informative cases (25/50) showed loss of heterozygosity for at least one of the 3p markers. 3p21 was the region with the highest rate of allelic deletion (63%). No point mutation was found in FHIT exon 5 or beta-cat exon 3. No case showed homozygous deletion for the FHIT (exons 5 and 6) or the beta-cat exon 3.
The short arm of chromosome 3 is often deleted in the head and neck squamous cell carcinomas. In the remaining alleles of the FHIT or beta-cat genes, no evidence was found for point mutations or deletions, documented in other common carcinomas. Inactivation could occur by different mechanisms such as methylation, or other genes (not studied here) could be target of allelic losses in squamous cell carcinoma of the head and neck.
研究头颈部鳞状细胞癌患者原发肿瘤中3号染色体短臂杂合性缺失情况；确定定位于3p14.2的FHIT基因和定位于3p21的CTNNB1（β-连环蛋白）基因在这些肿瘤中是否缺失或突变。
从新鲜肿瘤中提取DNA。通过对以下标记进行微卫星分析评估杂合性缺失：D3S1283和D3S1286（3p24）、D3S966（3p21）以及D3S1300（3p14.2）。通过对FHIT基因外显子5和6进行放射性多重聚合酶链反应确定纯合缺失。通过单链构象多态性研究FHIT外显子5和β-连环蛋白外显子3中突变的存在情况。
50%的信息充分病例（25/50）显示至少一个3p标记存在杂合性缺失。3p21是等位基因缺失率最高的区域（63%）。在FHIT外显子5或β-连环蛋白外显子3中未发现点突变。未发现病例存在FHIT（外显子5和6）或β-连环蛋白外显子3的纯合缺失。
3号染色体短臂在头颈部鳞状细胞癌中常发生缺失。在FHIT或β-连环蛋白基因的其余等位基因中，未发现其他常见癌症中记录的点突变或缺失证据。失活可能通过不同机制发生，如甲基化，或者其他基因（本文未研究）可能是头颈部鳞状细胞癌等位基因缺失的靶点。
