Kato M V, Ishizaki K, Shimizu T, Toguchida J, Kaneko A, Sasaki M S
Radiation Biology Center, Kyoto University, Japan.
Int J Cancer. 1995 Feb 20;64(1):3-8. doi: 10.1002/ijc.2910640103.
Loss of heterozygosity (LOH) on chromosome 13, which is associated with the functional inactivation of the retinoblastoma (RB) gene, is critical for the development of RB. To date, we have found that LOH-negative tumors develop earlier than LOH-positive tumors in hereditary cases of RB, an observation which suggests that loss of one allele on chromosome 13 may be disadvantageous with respect to growth of RB tumors. In this study, the parental origin of the lost allele on chromosome 13 and the age at operation of 13 patients with non-hereditary RB tumors that had been enucleated at the same stage were studied, in an attempt to determine whether there are any differences between tumors with loss of a maternal allele on chromosome 13 and tumors with loss of a paternal allele. Six tumors had lost the maternal allele and 7 tumors had lost the paternal allele on chromosome 13. The age (average 694 days) of patients at operation in the case of tumors with loss of the paternal allele was significantly lower than the age (average 1,079 days) of patients at operation for removal of tumors with loss of the maternal allele. RB tumors that had lost the maternal allele on chromosome 13 developed later than tumors that had lost the paternal allele. The possibility is discussed that loss of the maternal allele on chromosome 13 might be disadvantageous for growth of RB tumors.
13号染色体杂合性缺失（LOH）与视网膜母细胞瘤（RB）基因的功能失活相关，对RB的发生发展至关重要。迄今为止，我们发现在遗传性RB病例中，LOH阴性肿瘤比LOH阳性肿瘤发展得更早，这一观察结果表明13号染色体上一个等位基因的缺失可能对RB肿瘤的生长不利。在本研究中，对13例同期摘除的非遗传性RB肿瘤患者13号染色体上缺失等位基因的亲本来源及手术年龄进行了研究，以确定13号染色体上母源等位基因缺失的肿瘤与父源等位基因缺失的肿瘤之间是否存在差异。13号染色体上有6个肿瘤丢失了母源等位基因，7个肿瘤丢失了父源等位基因。父源等位基因缺失的肿瘤患者手术时的年龄（平均694天）显著低于母源等位基因缺失的肿瘤患者手术时的年龄（平均1079天）。13号染色体上母源等位基因缺失的RB肿瘤比父源等位基因缺失的肿瘤发展得更晚。文中讨论了13号染色体上母源等位基因缺失可能对RB肿瘤生长不利的可能性。
