자궁경부암에서 비정상적인 Fragile Histidine Triad (FHIT) 발현에 대한 연구 = Abnormal Fragile Histidine Triad (FHIT) Expression in Cervical Carcinomas

국문 초록 (Abstract)

목적 : 암의 발생기전과 관련하여 발암유전자, 항암유전자, 일정 염색체 부위의 변화 등에 대햐여 활발한 연구가 이루어지고 있다. FHIT 유전자는 3번 염색체 단완에 위치하는 종양억제 유전자의 하나로 폐암, 두경부암 등 상피세포암에서 발현되며, 최근의 연구에 따르면 자궁경부암에서도 이 유전자의 이상발현이 관찰되고 있다. 저자들은 자궁경부암 환자에서 FHIT 유전자의 이상발현을 RT-PCR 방법을 통해 분석하여 FHIT 유전자의 이상발현의 원인을 살펴보고 자궁경부암에서 예후 인자로 알려진 여러 인자들과 비교 분석하여 FHIT 이상 발현의 중요성을 알아보고자 하였다.
연구 방법 : 7개의 정상자궁경부 조직과 58개의 자궁경부암 조직을 대상으로 quantitative RT-PCR을 시행하여 FHIT 유전자의 mRNA 발현을 비교하고, 대상군의 의무기록을 통하여 임상병리학적 예후인자와의 상관관계를 분석하였다. 또한 genomic DNA PCr analysis 및 nonisotopic RT-PCR-SSCP, methylation-specific PCR을 시행하여 FHIT 발현이상의 원인을 규명하고자 하였다.
결과 : FHIT mRNA 발현 정도는 정상조직에서 평균 0.82±0.07, 자궁경부암 조직에서는 0.58±0.22로 정상조직에 비해 침윤암 조직에서 유의하게 감소되어 있는 양상이 관찰되었고 (p<0.05), 그 중 25.9％ (15/58)의 종양조직에서는 비정상적으로 감소되어 있는 것을 확인할 수 있었다. 그러나, FHIT mRNA 발현수준과 예후와 관련이 있는 임상병리과 특성과 유의한 상관관계를 발견하지 못하였다. 비정상적으로 mRNA 발현이 감소된 종양조직과 정상조직의 quantitative genomic DNA PCr 결과는 차이가 없었으며, RT-PCR-SSCP를 통해 20예의 종양조직에서 FHIT mutation 여부를 살펴본 결과 sequence의 변화를 발견할 수 없었다. 그러나, FHIT 발현의 비정상적인 감소를 보인 15예의 종양조직에서 GHIT promoter hypermethylation 여뷰를 조사한 결과 모두 양성으로 나타났고, 이에 반해 정상 자궁조직 7예와 정상발현을 보인 종양조직 43예 중 20예에서는 음성으로 관찰되었다.
결론 : 이상의 결과를 종합해 보면 FHIT 발현 정도는 침윤성 자궁경부암에서 유의하게 감소하는 것을 알 수 있었고, 이는 FHIT 유전자의 aberrant promoter hypermethylation에 의한 것으로 판단할 수 있었다.

다국어 초록 (Multilingual Abstract)

Objective : The fragile histidine triad (FHIT) gene is located at chromosome 3p14.2 and encompasses the common fragile site, FRA3B, which may contribute to chromosome breakage and rearrangement of cancer cells. In this study, we examined whether transcriptional alterations of FHIT gene play a role in the development of human cervical carcinomas and the possibility that hypermethylation of CpG islands serves for FHIT inactivation. We then analyzed FHIT expression status with clinical parameters to determine whether it has any prognostic significance. Methods : The study group included 50 squamous carcinoman, 4 adenocarcinomas 4 adenosquamous carcinomas, 7 noncancerous tissue and the clinical stage is composed of 4 Ia, 37 Ib and 17 II. Tissue specimens were snap-frozen in liquid N2 and stored at -70℃ until used. To examine for abnormal transcripts of the FHIT gene, quantitative RT-PCR, genomic DNA-PCR and nonisotopic RT-PCR-SSCP analysis were performed using the standard method. The methylation status was determined by methylation specific PCR. Results : The FHIT gene was down-regulated in 15 of (25.9％) cervical carcinomas. FHIT promoter hypermethylation was detected in 15 of 15 (100％) abnormally expression in cervical carcinomas. Conclusion : In this study, gene mutation is not a main mechanism for FHIT inactivation, but the aberrant promoter hypermethylation may be correlated with decreased expression of the FHIT gene. The significance of decreased expression of FHIT does not appear to be an independent prognostic factor in cervical cancers, although a still larger sample of patients will be required to asses this issue definitively.

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