膀胱移行细胞癌3号染色体短臂上抑癌基因杂合性缺失的研究

Loss of heterozygosity of tumor suppressor genes at chromosome 3p in transitional cell carcinoma of urinary bladder

目的 探讨位于 3号染色体短臂的候选抑癌基因FHIT、hMLH和VHL在中国人膀胱移行细胞癌 (TCC)发生中的可能作用。方法 选取 6个位于上述基因内含子或与上述基因紧密连锁的微卫星多态标记对 4 0例膀胱TCC组织进行杂合性缺失 (LOH)分析。结果 位于FHIT基因内含子内的两个微卫星多态标记 (D3S12 34和D3S130 0 )中至少有一个为杂合子的杂合率为 95 0 % (38/ 4 0 ) ,至少有一个发生LOH的频率为 5 7 8% (2 2 / 38)。与hMLH1基因连锁的两个微卫星多态标记 (D3S15 6 1和D3S16 12 )中至少有一个为杂合子的杂合率为 5 5 0 % (2 2 / 4 0 ) ,至少有一个发生LOH的频率为 5 9 1%(13/ 2 2 )。与VHL基因连锁的两个微卫星多态标记 (D3S10 38和D3S12 84 )中至少有一个为杂合子的杂合率为 90 0 % (36 / 4 0 ) ,至少有一个发生LOH的频率为 4 7 2 % (17/ 36 )。在所检测微卫星多态标记中仅D3S12 84的LOH与膀胱TCC的病理分期正相关 (P <0 0 5 ) ,余微卫星多态标记的LOH与膀胱移行细胞癌病理分级及病理分期均不相关 (P >0 0 5 )。结论 上述 3个基因在膀胱TCC中存在高频率LOH ,提示它们可能在膀胱TCC的发生发展中起重要作用。FHIT基因和hMLH1基因的缺失作为分子标志有可能为膀胱TCC的早期诊断提供新的途径和依据 。

Objective To investigate the potential effects of three tumor suppressor genes located at chromosome 3p, FHIT, hMLH1 and VHL, in carcinogenesis of transitional cell carcinoma (TCC) of urinary bladder in Chinese. Methods PCR was used to examine the heterozygosity and loss of heterozygosity (LOH) of the 6 microsatellite polymorphic markers inside of or flanking to the three genes tumor suppressor genes FHIT, hMLHi, and VHL in TCC tissues of 40 cases. Results The rates of heterozygosity and LOH were 55 0% (38/40) and 59 1% (22/38) for hMLH1 gene. The rates of heterozygosity and LOH were 90 0% (36/40) and 47 2% (17/36) The rate of heterozygosity of the two microsatellite polymorphic markers in the intron of FHIT gene, D2S1234 and D3S1300, were 70%(28/40)和67 5%(27/40),The LOH rates of D2S1234 and D3S1300 were 46 4%(13/28) and 37%(10/27) respectively. The rate that at least one the these 2 microsatellite polymorphic markers was heterozygote was 95 0%(38/40), the rate that LOH occurred for at least one of them was 57 8%(22/38). The heterozygosity rate of D3S1561 and D3S1612, two microsatellite polymorphic markers linked to hMLH1 gene, were 42 5%(17/40) and 30%(12/40) respectively, the LOH rates for these two markers were 41 2%(7/17) and 75.0%(9/12) respectively, the rate that at least one of these two markers was heterozygote was 59 1% (13/22). The heterozygosity rate of D3S10368 and D3S1284, two microsatellite polymorphic markers linked to VHL gene, were 70%(28/40) and 47 5% (19/40) respectively, the LOH rates for these two markers were 42 8% (12/28) and 42 1%(8/19) respectively, the rate that at least one of these two markers was heterozygote was 90 0%(36/40). High frequencies of LOH were found in tumor suppressor genes FHIT, hMLH1 and VH. Only the LOH of D3S1284 was positively correlated with the pathological staging of TCC of urinary bladder ( P <0 05). Conclusion LOH in tumor suppressor genes FHIT, hMLH1 and VHL may play an important role in carcinogenesis of human urinary bladder, and may provide new approaches for early detection of TCC. Loss of VHK gene may be a late event of carcinogenesis of TCC.