Pavelic K, Hrascan R, Kapitanovic S, Vranes Z, Cabrijan T, Spaventi S, Korsic M, Krizanac S, Li Y Q, Stambrook P, Gluckman J L, Pavelic Z P
Department of Molecular Medicine, Ruder Boskovic Institute, Zagreb, Croatia.
Anticancer Res. 1996 Jul-Aug;16(4A):1707-17.
Malignant insulinoma is an rare form of cancer with poor prognosis and a reported 5-year survival of 35%. Relatively little is known about the etiology of this disease or of the oncogenes and tumor suppressor genes that participate in its genesis and progression. To address this issue, several protooncogenes, including K-ras, N-ras, erbB-2, erbB-3,c-myc, c-fos, c-jun were examined. Also analyzed was the expression of the growth factors TGF-alpha, EGF, and insulin as well as the EGF receptor (EGF-R), p53 and the putative anti-metastasis gene nm23-H1. These were examined in malignant insulinomas, benign insulinomas, pancreatic B cell hyperplasias and in normal endocrine pancreas. Normal endocrine pancreas showed moderate immunoreaction for c-myc and a strong reaction for insulin. All other parameters were negative. Benign pancreatic B cell hyperplasias were slightly or moderately positive for N-ras and TGF-alpha, and were weakly positive for EGF-R. They were strongly positive for c-myc and insulin. In malignant insulinomas there was strong immunoreaction for c-myc, TGF-alpha, N-ras, K-ras and p53. Insulin reaction was moderate or strong. Molecular genetic studies have been performed for the presence of activating point mutations in codon 12 of the c-K-ras oncogene. Mutations were detected using primer-mediated, mutant-enriched, polymerase chain reaction-restriction fragment length polymorphism analysis and were further characterized by allele-specific oligonucleotide hybridization. Four out of six patients with malignant insulinoma and two out of eight patients with benign insulinoma harbored K-ras point mutations at codon 12. All patients with mutated K-ras oncogene also had elevated levels of p53 protein as well as c-myc and TGF-alpha. In one extremely malignant case we found concomitant mutation at codon 12 of K-ras and codon 61 of the N-ras gene. Our data are consistent with the idea that malignant progression is accompanied by the progressive accumulation of multiple genetic lesions and suggest that activation of myc, TGF-alpha and ras genes may be early events in the development of insulinoma.
恶性胰岛素瘤是一种罕见的癌症，预后较差，据报道其5年生存率为35%。关于这种疾病的病因以及参与其发生和发展的癌基因和肿瘤抑制基因，人们所知相对较少。为了解决这个问题，研究了几种原癌基因，包括K-ras、N-ras、erbB-2、erbB-3、c-myc、c-fos、c-jun。还分析了生长因子TGF-α、EGF和胰岛素以及EGF受体（EGF-R）、p53和假定的抗转移基因nm23-H1的表达。在恶性胰岛素瘤、良性胰岛素瘤、胰腺B细胞增生以及正常内分泌胰腺中对这些进行了检测。正常内分泌胰腺对c-myc呈中度免疫反应，对胰岛素呈强反应。所有其他参数均为阴性。良性胰腺B细胞增生对N-ras和TGF-α呈轻度或中度阳性，对EGF-R呈弱阳性。它们对c-myc和胰岛素呈强阳性。在恶性胰岛素瘤中，对c-myc、TGF-α、N-ras、K-ras和p53呈强免疫反应。胰岛素反应为中度或强阳性。已经对c-K-ras癌基因第12密码子中的激活点突变进行了分子遗传学研究。使用引物介导的、富含突变体的聚合酶链反应-限制性片段长度多态性分析检测突变，并通过等位基因特异性寡核苷酸杂交进一步表征。6例恶性胰岛素瘤患者中有4例以及8例良性胰岛素瘤患者中有2例在第12密码子处存在K-ras点突变。所有K-ras癌基因突变的患者p53蛋白以及c-myc和TGF-α水平也升高。在1例极恶性病例中，我们发现K-ras第12密码子和N-ras基因第61密码子同时发生突变。我们的数据与恶性进展伴随着多种基因损伤的逐步积累这一观点一致，并表明myc、TGF-α和ras基因的激活可能是胰岛素瘤发生发展的早期事件。
