高转移性人肺癌细胞系p53基因突变的研究

MUTATION OF P53 GENE IN A HIGHLY METASTATIC HUMAN LUNG CANCER CELL LINE

ＰＧ癌系为来自人巨细胞型肺癌的体外细胞系，具有生长快和成瘤率高的特性。裸小鼠移植后，肺和淋巴结的自发转移性频率高，而且稳定。为了深入了解其生物学特性的分子基础，对其细胞和分子生物学改变作了系统的分析。结果表明：免疫组化发现ｐ５３蛋白的异常高表达；用非同位素ＰＣＲ－ＳＳＣＰ法检测到第７外显子的单链多态性变化，提示有碱基组成的改变。对该外显子的两条链用热循环ＤＮＡ测序法分析后，证实第２４８密码子有ＣＧＧ→ＣＴＴ的碱基颠换；同时以上述方法检测了Ｋｉ－ｒａｓ癌基因的点突变，未发现ｋｉ－ｒａｓ突变。结合文献探讨了ｐ５３基因突变的生物学意义，这一研究为进一步研究ｐ５３基因与ＰＧ癌细胞生物学特性的关系奠定了基础。

AbstractPG cell line , derived from a lung giant cell carcinoma,has the characteristics of rapid growthand high tumorigenicity. When transplanted to nude mice , spontanious metastasis to lung andlymphnode is high in frequency and stable. To understandthe molecular basis of PG’s biologicalbehaviors , expression of tumor suppressor gene p53 was studied. It was found that expression ofp53 protein was increased as demonstrated by immunohistochemical stainning. A change in poly-morphsim in exon 7 of p53 gene was detected by nonisotopic PCR-SSCP, suggesting a change inbase composition. Thermalcycling sequencing of both strands of exon 7 demonstrated a transver-sion of CGG to CTT at codon 248. Similar study with the same methods on Ki-ras oncogene wasdone , but no mutation was found. The relationship between p53 gene mutation and the metastat-ic potential of PG cells needs further exploration.