Analysis of p73 in human borderline and invasive ovarian tumor.
Analysis of p73 in human borderline and invasive ovarian tumor.
复制标题
人类交界性和侵袭性卵巢肿瘤中 p73 的分析。
作者：
Ng,SW;Yiu,GK;Liu,Y;Huang,LW;Palnati,M;Jun,SH;Berkowitz,RS;Mok,SC
p73是一个新基因，与抑癌基因p53具有高度的序列同源性和相似的基因结构。我们分析了 7 个卵巢癌细胞系和总共 63 个人类交界性和侵袭性卵巢肿瘤样本中的 p73。在 50% 的侵袭性肿瘤中观察到该基因座杂合性丢失，但没有在交界性肿瘤中观察到。在杂合肿瘤组织中观察到该基因的双等位基因表达。对与p53高度突变区同源的p73 cDNA序列进行直接测序和单链构象多态性分析，没有发现任何突变。与正常人卵巢表面上皮细胞和永生化细胞系的原代培养物相比，七种卵巢癌细胞系中的四种、71%的侵袭性肿瘤和92%的交界性肿瘤组织表达升高水平的p73转录物。除 OVCA3 细胞系外，从细胞系制备的核提取物的蛋白质印迹分析显示 p73 蛋白水平一致。我们的分析还证明，仅在癌细胞系和侵袭性肿瘤组织中表达了省略外显子 2 的 p73 转录本的剪接变体。该外显子 2 剪接转录物将产生没有 N 末端反式激活结构域的截短 p73 蛋白。让人想起另一个p53相关基因p63的N端截短变体的显性失活表型，卵巢肿瘤中截短的p73变体形式的表达可能在卵巢癌的发病机制中发挥重要作用。
p73 is a novel gene that has high sequence homology and similar gene structure to the tumor suppressor gene p53. We analysed p73 in seven ovarian carcinoma cell lines and a total of 63 human borderline and invasive ovarian tumor samples. Loss of heterozygosity at this locus was observed in 50% of invasive tumors but in none of the borderline tumors. Biallelic expression of the gene was observed in the heterozygous tumor tissues. Direct sequencing and single-strand conformation polymorphism analyses of the p73 cDNA sequence homologous to the highly mutatable region of p53 did not reveal any mutations. When compared to the primary cultures of normal human ovarian surface epithelial cells and immortalized cell lines, four of the seven ovarian carcinoma cell lines, 71% of the invasive tumors, and 92% of the borderline tumor tissues express elevated levels of p73 transcript. Except for the OVCA3 cell line, Western blot analysis of the nuclear extracts prepared from the cell lines showed concordant levels of p73 protein. Our analysis also demonstrated the expression of a spliced variant of p73 transcript with the omission of exon 2 solely in the cancer cell lines and invasive tumor tissues. This exon 2-spliced transcript would give rise to a truncated p73 protein without the N-terminal transactivation domain. In reminiscence of the dominant negative phenotype of the N-terminal truncated variants of another p53-related gene, p63, the expression of the truncated p73 variant form in ovarian tumors may play an important role in the pathogenesis of ovarian cancer.