Greenspan D L, Connolly D C, Wu R, Lei R Y, Vogelstein J T, Kim Y T, Mok J E, Muñoz N, Bosch F X, Shah K, Cho K R
Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Cancer Res. 1997 Nov 1;57(21):4692-8.
Allelic deletions involving the short arm of chromosome 3 (3p13-21.1) have been observed frequently in cervical carcinomas. Recently, a candidate tumor suppressor gene, FHIT (Fragile Histidine Triad), was cloned and mapped to this chromosomal region (3p14.2). Abnormal FHIT transcripts have been identified previously in a variety of tumor cell lines and primary carcinomas, although their significance and the molecular mechanisms underlying their origin remain incompletely defined. In addition, integration of human papillomavirus DNA has been identified at a fragile site (FRA3B) within the FHIT locus in cervical cancer. These observations motivated us to evaluate FHIT mRNA and protein expression in cervical cancer cell lines, primary cervical carcinomas, and normal tissues. Transcripts of the expected size and sequence were the predominant species identified by reverse transcription (RT)-PCR in cultured keratinocytes and all normal tissues evaluated. In contrast, aberrant FHIT transcripts were readily demonstrated in 6 of 7 cervical carcinoma cell lines and 17 of 25 (68%) primary cervical carcinomas. Northern blot analyses demonstrated reduced or absent FHIT expression in the cervical carcinoma cell lines, particularly those with aberrant RT-PCR products. Immunohistochemical analysis of Fhit expression in cervical tissues revealed strong immunoreactivity in nonneoplastic squamous and glandular cervical epithelium and marked reduction or loss of Fhit protein in 25 of 33 (76%) primary cervical carcinomas. In those cervical cancer cell lines and primary tumors with exclusively aberrant or absent FHIT transcripts by RT-PCR, Fhit protein expression was always markedly reduced or absent. The frequent alterations in FHIT expression in many cervical carcinomas, but not in normal tissues, suggest that FHIT gene alterations may play an important role in cervical tumorigenesis.
在宫颈癌中经常观察到涉及3号染色体短臂（3p13 - 21.1）的等位基因缺失。最近，一个候选肿瘤抑制基因，脆性组氨酸三联体（FHIT）基因被克隆并定位于该染色体区域（3p14.2）。先前已在多种肿瘤细胞系和原发性癌中鉴定出异常的FHIT转录本，尽管它们的意义以及其产生的分子机制仍未完全明确。此外，在宫颈癌的FHIT基因座内的一个脆性位点（FRA3B）处已鉴定出人乳头瘤病毒DNA的整合。这些观察结果促使我们评估FHIT mRNA和蛋白在宫颈癌细胞系、原发性宫颈癌和正常组织中的表达。通过逆转录（RT）-PCR在培养的角质形成细胞和所有评估的正常组织中鉴定出的预期大小和序列的转录本是主要类型。相比之下，在7个宫颈癌细胞系中的6个以及25个原发性宫颈癌中的17个（68%）中很容易检测到异常的FHIT转录本。Northern印迹分析表明宫颈癌细胞系中FHIT表达降低或缺失，尤其是那些具有异常RT-PCR产物的细胞系。对宫颈组织中Fhit表达的免疫组织化学分析显示，在非肿瘤性宫颈鳞状上皮和腺上皮中有强免疫反应性，而在33个原发性宫颈癌中的25个（76%）中Fhit蛋白明显减少或缺失。在那些通过RT-PCR仅具有异常或缺失FHIT转录本的宫颈癌细胞系和原发性肿瘤中，Fhit蛋白表达总是明显降低或缺失。许多宫颈癌中FHIT表达频繁改变，而正常组织中未出现这种情况，这表明FHIT基因改变可能在宫颈肿瘤发生中起重要作用。
