多基因表达对IIIA期非小细胞肺癌术后转移及生存期的影响

目的前瞻性探讨抑癌基因p53,癌基因K-ras、HER2, 血管内皮生长因子(VEGF),表皮生长因子受体(EGFR),粘连因子CD44,金属蛋白酶MMP9等蛋白表达对ⅢA期非小细胞肺癌(NSCLC)术后复发转移和生存期的影响.方法采用免疫组织化学方法检测32例ⅢA期非小细胞肺癌手术标本中上述蛋白表达.结果 p53、K-ras、VEGF、EGFR、CD44、MMP9和HER2蛋白表达率分别为62.5%(20/32)、34.3%(11/32)、25.0%(8/32)、46.9%(15/32)、78.1% (25/32)、50%(16/32)和43.8%(14/32).K-ras,EGFR蛋白表达与疾病进展时间(time to progression,TTP)有关(P=0.030, P=0.008).多变量Cox回归分析,K-ras,HER2蛋白表达是影响生存期的独立影响因素.Kaplan-M 生存分析显示K-ras,HER2 阳性组生存期明显短于阴性组(P=0.042,P=0.039).结论对于ⅢA期NSCLC,上述7种因子阳性表达率很高.K-ras,EGFR蛋白表达阳性患者术后更易发生远处转移, K-ras,HER2表达是影响生存期的独立影响因素.     

非小细胞肺癌中EGFR和K-ras基因突变与蛋白表达相关性的研究

背景与目的：当前表皮生长因子受体（epidermal growth factor receptor,EGFR）基因靶向治疗已成为晚期非小细胞肺癌（non-small cell lung cancer,NSCLC）治疗的研究的热点之一。本研究旨在探讨NSCLC患者中EGFR基因和K-ras（Kirsten rat sarcoma viral oncogene）基因突变的情况,分析其与蛋白表达的相关性及对吉非替尼（gefitinib）治疗的指导意义。方法：收集200例NSCLC患者新鲜组织,采用基因测序法检测EGFR及K-ras基因突变的状态;同时采用免疫组织化学法检测EGFR和K-ras蛋白的表达。结果：200例患者中,EGFR基因突变率为33%,主要发生在19号和21号外显子;K-ras基因突变率为5.5%,主要位于第12密码子;不存在同时携带有EGFR和K-ras两种基因突变的病例。腺癌尤其是含细支气管肺泡癌（bronchioloalveolar carcinoma,BAC）病理分型的患者、非吸烟患者和女性患者EGFR突变率较高。EGFR蛋白表达阳性率为16%,与总的EGFR突变无关（P〉0.05）,但与19号外显子突变具有统计学意义（P〈0.05）。K-ras蛋白表达阳性率为52.5%,与K-ras基因突变无关（P〉0.05）。15例携带有EGFR基因突变的NSCLC患者服用吉非替尼,12例（其中8例为EGFR蛋白表达阴性）有效。结论：EGFR蛋白表达与EGFR基因19号外显子突变具有一定相关性;联合检测EGFR和K-ras基因突变可用来筛选对EGFR酪氨酸激酶抑制剂（tyrosine kinase inhibitor,TKI）治疗敏感的人群,并预测吉非替尼治疗晚期NSCLC的疗效及预后。     

Specific inhibition of K-ras expression and tumorigenicity of lung cancer cells by antisense RNA

A human lung cancer cell line (H460a) with a homozygous spontaneous K-ras mutation was transfected with a recombinant plasmid that synthesizes a 2-kilobase genomic segment of the K-ras protooncogene in antisense orientation. Translation of the mutated K-ras mRNA in H460a cells was specifically inhibited, whereas expression of H-ras and N-ras was unchanged. A 3-fold growth inhibition occurred in H460a cells when expression of the mutated ras p21 protein was down-regulated by antisense RNA. However, cells remained viable despite the absence of K-ras expression. The growth of H460a tumors in nu/nu mice was substantially reduced by expressed K-ras antisense RNA.     

p53 enhances gefitinib-induced growth inhibition and apoptosis by regulation of Fas in non-small cell lung cancer

Treatment with gefitinib, a specific inhibitor of epidermal growth factor receptor tyrosine kinase (EGFR-TK), has resulted in dramatic responses in some patients with non-small cell lung cancer (NSCLC). Most patients who respond to gefitinib have EGFR-TK mutations; however, >10% of patients with EGFR-TK mutations do not respond. Similarly, some patients without EGFR-TK mutations respond to this drug, suggesting that other factors determine sensitivity to gefitinib. Aberrations of the tumor suppressor gene p53 are frequently associated with drug resistance. In this study, we investigated the role of p53 in growth-inhibitory and apoptotic effects of gefitinib in the human NSCLC cell lines NCI-H1299 and A549, which have no EGFR-TK mutations. NCI-H1299 cells, which had a p53-null genotype, were more resistant to gefitinib compared with A549 cells, which were wild-type p53 (IC(50), 40 micromol/L in NCI-H1299 and 5 micromol/L in A549). Treatment of A549 with gefitinib resulted in the translocation of p53 from cytosol to nucleus and the up-regulation of Fas, which was localized to the plasma membrane. In the stable H1299 cell line with tetracycline-inducible p53 expression, induced p53 enhanced growth inhibition and apoptosis by gefitinib through the up-regulation of Fas and restoration of caspase activation. A caspase inhibitor, Z-VAD-fmk, reduced these effects. Conversely, inhibition of p53 using antisense oligonucleotide in A549 caused a significant decrease in apoptosis by gefitinib and down-regulation of Fas under the same conditions. In conclusion, p53 may play a role in determining gefitinib sensitivity by regulating Fas expression in NSCLC.     

The K-ras gene regulates vascular endothelial growth factor gene expression in non-small cell lung cancers

Tumor angiogenesis is an essential step for tumor cell growth, progression and metastasis. Vascular endothelial growth factor (VEGF) is mitogen specific for endothelial cells, and therefore is believed to play a key role in tumor angiogenesis. However, the mechanisms underlying the regulation of VEGF expression remain virtually unknown and the only major regulator of VEGF expression has been reported to be hypoxia. Recently, it was reported that a mutant p53 in#duced the expression of VEGF mRNA, and that wild-type p53 down-regulated endogenous VEGF mRNA levels. In contrast, it has also been reported that mutant ras oncogenes were associated with the marked up-regulation of VEGF in transformed epithelial cells. Based on these results, we performed a retrospective study of the p53 and K-ras genes status and VEGF gene expression in the tumor tissues from 181 patients with non-small cell lung cancer using SSCP, sequencing, RT-PCR and immunohistochemical techniques. Forty-six carcinomas (25.4%) were evaluated as having high VEGF expression, and 135 tumors (74.6%) had low VEGF expression. Of the 181 primary NSCLC studied, 63 carcinomas (34.8%) contained mutations of p53, whereas only 14 carcinomas (7.7%) had mutations of K-ras. There were no significant relationships between VEGF expression and p53 status or each mutant exon of p53. In contrast, a significant difference was found between VEGF expression and K-ras status. Of the 14 tumors with mutant K-ras genes, 7 cases (50.0%) had high VEGF expression whereas only 39 of the 167 tumors with wild-type K-ras (23.4%) had high VEGF expression (p=0.0278). The mean VEGF conservation rate for the 14 tumors with mutant K-ras genes was 0.77+/-0.58 and the rate of the 167 tumors with wild-type K-ras genes was 0.49+/-0.46 (p=0. 0350). Moreover, the overall survival rate of patients with high VEGF expression was lower than patients with low VEGF expression (45.7% vs 60.7%, p=0.0419). On the other hand, there was no significant difference in the overall survival rate between patients with a mutant p53 and those with a wild-type p53; there was also no difference in the overall survival between patients with a mutant K-ras and those with a wild-type K-ras. The Cox regression model analysis indicated that three variables, VEGF status, K-ras status and nodal status, were found to be significant indicators for prognosis (p=0.0236, p=0.0172 and p<0.0001, respectively). Our data suggest that a high expression of VEGF in lung cancer may be associated with a poor prognosis. This may be a clue to improving lung cancer diagnoses and therapies aimed at inhibiting tumor angiogenesis due to VEGF.     

Analysis of K-ras, p53, bcl-2 and Rb expression in non-small cell lung cancer cell lines

Six non-small cell lung cancer (NSCLC) cell lines (A-549, Ca-Lu-6, SK-Lu-1, Ca-Lu-1, SK-Mes-1 and LX-1) were studied to assess the presence of multiple concomitant alterations of different oncogenes (K-ras, bcl-2) and tumor suppressor genes (p53, Rb) in NSCLC. K-ras (exon 1) and p53 (exons 5-8) gene mutations were determined via a PCR-based-DGGE (Denaturing Gradient Gel Electro-phoresis) and by sequencing approach. Different mutations were found in the Ist exon of K-ras gene in 5 of 6 cell lines examined. Five of six cell lines contained K-ras mutations at codon 12 (A-549, SK-Lu-1, LX-1) or codon 13 (SK-Mes-1, Ca-Lu-1). In addition, 5 of 6 cell lines showed p53 mutations of exon 8 (SK-Mes-1, Ca-Lu-1 cod. 280; LX-1 cod. 273) or exon 6 (Ca-Lu-6 cod. 196; SK-Lu-1 cod. 193). In 4 of these cell lines, p53 protein nuclear expression was also confirmed with DO-7 mAb immunocytochemistry. Expression of cytoplasmic bcl-2 protein, by anti-bcl-2 mAb flow cytometric analysis, was found in A-549, Ca-Lu-1, SK-Lu-1, SK-Mes-1 cell lines. In contrast, RT-PCR analysis of Rb gene could not identify any change in the cell lines examined. In conclusion, most NSCLC cell lines tested displayed concomitant multiple oncogene/tumor suppressor gene alterations.     

Prognostic significance of K-ras,p53, bcl-2, PCNA,CD34 in radically resected non-small cell lung cancers

The aim of this study was to investigate the prognostic significance of a panel of biological parameters in patients with radically resected non-small cell lung cancers (NSCLC). 269 cases with pathological stage I-IIIA NSCLC were retrospectively analysed. Immunohistochemistry was performed to detect protein expression of p53, bcl-2, proliferating cell nuclear antigen (PCNA) and CD34. Polymerase chain reaction (PCR)/direct nucleotide sequencing method was used to detect mutations in K-ras (codons 12, 13, 61, exons 1-2). The Kaplan-Meier estimates of survival were calculated for clinical and biological variables using the Cox model for multivariate analysis. Histological subtype and the pathologic tumour extension (pT) were the most powerful clinical-pathological prognostic factors for survival (P=0.030 and P=0.031, respectively), whereas among the biological parameters, p53 overexpression (P=0.032) and K-ras mutation (P=0.078) had a negative prognostic role, as demonstrated by multivariate analysis. Conversely, bcl-2, PCNA and CD34 expression were not correlated with survival. Statistically significant associations between p53 expression and the squamous cell carcinoma (SCC) subtype, bcl-2 expression and SCC subtype, K-ras mutation and p53 negative expression, p53 and bcl-2, bcl-2 and PCNA overexpression were observed. In conclusion, some biological characteristics such as the K-ras and p53 status may provide useful prognostic information in resected NSCLC patients, in addition to the classical clinico-pathological parameters. However, further studies are needed to clarify the value of adopting biological prognostic factor into clinical practice.     

Cyr61 suppresses the growth of non-small-cell lung cancer cells via the beta-catenin-c-myc-p53 pathway

Cysteine-rich protein 61 (Cyr61) is a growth factor-inducible, immediate-early gene that has multifaceted activities in various cancers. In a previous study, we found that Cyr61 inhibited the growth of the H520 and H460 non-small-cell lung cancer (NSCLC) cell lines. In further studies, we now report that p53 plays a pivotal role in Cyr61-dependent cellular growth arrest. Blocking Cyr61 with a Cyr61 antibody resulted in the downregulation of expression of p53 and p21, as well as partially reversing the growth suppression of H520-Cyr61 cells. Proliferation of NSCLC cell lines (NCI-H157, H125, H1299), having a mutant p53, were not suppressed by Cyr61. Inhibition of wild-type p53, by either human papilloma virus type 16 E6 or a dominant-negative p53, resulted in the rescue of the growth suppression mediated by Cyr61 in the H520-Cyr61 cells. The enhanced levels of p21WAF1 and p130/RB2, in the Cyr61-expressing H520-Cyr61 cells, were also inhibited by blocking p53 showing that p21 and p130 were induced by p53 in these cells. In addition, levels of both c-myc and beta-catenin increased in Cyr61 stably transfected H520 cells. Moreover, beta-catenin was translocated into the nucleus in these cells. Inhibition of c-myc expression in the H520-Cyr61 cells with antisense c-myc resulted in their decreased levels of p53. Transfecting cells with a dominant-negative T-cell factor (TCF4), the specific inhibitor of the beta-catenin/TCF4 complex, downregulated the expression of c-myc. Taken together, the data suggest that Cyr61 suppressed the growth of NSCLC cells by triggering a signal transduction pathway through beta-catenin. In this pathway, Cyr61 activated the beta-catenin/TCF4 complex, which promoted the expression of c-myc and the latter induced expression of p53, and p53 upregulated p21WAF1 and p130/RB2, resulting in growth arrest.     

Ras and p53 expression in non-small-cell lung-cancer patients - p53 over-expression correlates with a poor prognosis

Expression of the tumor suppressor gene p53 and the ras oncogene were examined in 46 tumor and nodal specimens of non-small cell lung cancer (NSCLC) using the antibodies p53 pAb 240 and ras Y13-259 respectively. p53 expression was elevated in 46% and ras p21 was over-expressed in 85% of the tumor specimens analyzed. Fifteen cases of benign lessions were also assessed for both ras p21 and p53 expression; all were found to have negative staining. p53 over-expression was found to correlate with a poor prognosis in both the tumor specimens (p<0.05) and in the nodal tissues (p<0.005). Ras p21 over-expression was found to be associated with survival (p<0.1) in both the tumor and the nodal specimens. Stage of the disease correlated with survival; similarly both p53 and ras p21 over-expression correlated with stage. No correlations were found with the pathological grade of the tumors nor with a history of smoking or duration of smoking. No K-ras mutations at codon 12 were observed in a further 15 NSCLC specimens analyzed. These results indicate that the p53 gene in particular plays a role in the stages of NSCLC.     

Vascular endothelial growth factor and nitric oxide synthase expression in human lung cancer and the relation to p53.

Vascular endothelial growth factor (VEGF) expression and mutations of cancer-related genes increase with cancer progression. This correlation suggests the hypothesis that oncogenes and tumour suppressors regulate VEGF, and a significant correlation between p53 alteration and increased VEGF expression in human lung cancer was reported recently. To further examine this hypothesis, we analysed VEGF protein expression and mutations in p53 and K-ras in 27 non-small-cell lung cancers (NSCLC): 16 squamous cell, six adenocarcinomas, one large cell, two carcinoids and two undifferentiated tumours. VEGF was expressed in 50% of the squamous cell carcinomas (SCC) and carcinoids but none of the others. p53 mutations occurred in 14 tumours (52%), and K-ras mutations were found in two adenocarcinomas and one SCC; there was no correlation between the mutations and VEGF expression. As nitric oxide also regulates angiogenesis, we examined NOS expression in NSCLC. The Ca2+-dependent NOS activity, which indicates NOS1 and NOS3 expression, was significantly reduced in lung carcinomas compared with adjacent non-tumour tissue (P < 0.004). Although the Ca2+-independent NOS activity, which indicates NOS2 expression, was low or undetectable in non-tumour tissues and most carcinomas, significant activity occurred in three SCC. In summary, our data do not show a direct regulation of VEGF by p53 in NSCLC. Finally, we did not find the up-regulation of NOS isoforms during NSCLC progression that has been suggested for gynaecological and breast cancers.     

Overexpression of MDM2 in MCF-7 Promotes Both Growth Advantage and p53 Accumulation in Response to Estradiol

The overexpression of the oncogene product MDM2 is often observed in human breast cancer cells, especially in estrogen receptor (ER)-positive ones. To study the role of MDM2 protein in ER-positive breast cancer, we have established cell lines derived from MCF-7 which stably express increased and decreased levels of MDM2 by transfection of a mammalian expression vector containing human mdm2 cDNA in sense and antisense orientations, respectively. Interestingly, MDM2 overexpression in MCF-7 cells afforded a remarkable growth advantage under estradiol (E2)-sup-plemented condition. Then, we analyzed the expression of p53, which is an important regulator of growth and the cell cycle. Unexpectedly, the p53 accumulation induced by E2 was remarkably higher in MCF-7 cells stably overexpressing MDM2 than in the parent MCF-7 cells. On the other hand, reduction of MDM2 suppressed the E2-induced increase in p53 protein. Moreover, mdm2 antisense oligonucleotides prevented E₂-induced accumulation of p53. In the steady state, the cellular levels of p53 were also correlated with those of MDM2. These interactions are not consistent with the well-known role of MDM2, which acts as a negative regulator for p53 by inhibiting its function and promoting its rapid degradation. These results suggest that MDM2 may regulate the expression of p53 in the steady state and in response to E2 in breast cancer cells, and imply a novel and important role of MDM2 during breast carcinogenesis.     

Overexpression of MDM2 in MCF-7 promotes both growth advantage and p53 accumulation in response to estradiol.

The overexpression of the oncogene product MDM2 is often observed in human breast cancer cells, especially in estrogen receptor (ER)-positive ones. To study the role of MDM2 protein in ER-positive breast cancer, we have established cell lines derived from MCF-7 which stably express increased and decreased levels of MDM2 by transfection of a mammalian expression vector containing human mdm2 cDNA in sense and antisense orientations, respectively. Interestingly, MDM2 overexpression in MCF-7 cells afforded a remarkable growth advantage under estradiol (E2)-supplemented condition. Then, we analyzed the expression of p53, which is an important regulator of growth and the cell cycle. Unexpectedly, the p53 accumulation induced by E2 was remarkably higher in MCF-7 cells stably overexpressing MDM2 than in the parent MCF-7 cells. On the other hand, reduction of MDM2 suppressed the E2-induced increase in p53 protein. Moreover, mdm2 antisense oligonucleotides prevented E2-induced accumulation of p53. In the steady state, the cellular levels of p53 were also correlated with those of MDM2. These interactions are not consistent with the well-known role of MDM2, which acts as a negative regulator for p53 by inhibiting its function and promoting its rapid degradation. These results suggest that MDM2 may regulate the expression of p53 in the steady state and in response to E2 in breast cancer cells, and imply a novel and important role of MDM2 during breast carcinogenesis.     

Lack of prognostic significance of p53 and K-ras mutations in primary resected non-small-cell lung cancer on E4592: a Laboratory Ancillary Study on an Eastern Cooperative Oncology Group Prospective Randomized Trial of Postoperative Adjuvant Therapy.

PURPOSE: To determine the prognostic and predictive significance of p53 and K-ras mutations in patients with completely resected non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Patients were randomized preoperatively to receive adjuvant postoperative radiotherapy (Arm A) or radiotherapy plus concurrent chemotherapy (Arm B). p53 protein expression was studied by immunohistochemistry (IHC) and p53 mutations in exons 5 to 8 were evaluated by single-strand conformational analysis. K-ras mutations in codons 12, 13, and 61 were determined using engineered restriction fragment length polymorphisms. RESULTS: Four hundred eighty-eight patients were entered onto E3590; 197 tumors were assessable for analysis. Neither presence nor absence of p53 mutations, p53 protein expression, or K-ras mutations correlated with survival or progression-free survival. There was a trend toward improved survival for patients with wildtype K-ras (median, 42 months) compared with survival of patients with mutant K-ras who were randomized to chemotherapy plus radiotherapy (median, 25 months; P = .09). Multivariate analysis revealed only age and tumor stage to be significant prognostic factors, although there was a trend bordering on statistical significance for K-ras (P = .066). Analysis of survival difference by p53 by single-stranded conformational polymorphism and IHC, interaction of p53 and K-ras, interaction of p53 and treatment arm, nodal station, extent of surgery, weight loss, and histology did not reach statistical significance. CONCLUSION: p53 mutations and protein overexpression are not significant prognostic or predictive factors in resected stage II or IIIA NSCLC. K-ras mutations may be a weak prognostic marker. p53 or K-ras should not be routinely used in the clinical management of these patients.     

非小细胞肺癌CT与相关基因表达的研究

目的：研究非小细胞（ＮＳＣＬＣ）肺癌ＣＴ征象与肺癌相关基因ｐ５３,Ｃ－ｍｙｃ,Ｋ－ｒａｓ,及Ｃ－ｅｒｂＢ２表达间的关系。方法：运用免疫组化法,检测５４例经手术病理证实的非小细胞肺癌组织中的ｐ５３,Ｃ－ｍｙｃ,Ｋ－ｒａｓ及Ｃ－ｅｒｂＢ２基因的表达,并分析其与术前ＣＴ征象间的关系。结果：ｐ５３表达与非小细胞肺癌期别及ＣＴ征象中瘤体大小,深分叶征,毛刺征,空洞征,及纵隔淋巴结转移有关,但与组织类型胸,胸     

多基因表达预测可手术ⅢA期非小细胞肺癌新辅助化疗疗效的探讨

背景与目的ⅢA期非小细胞肺癌(non-smallcelllungcancer,NSCLC)新辅助化疗作用仍存在争议,多种基因表达虽然存在一定预后意义,但对预测ⅢA期NSCLC新辅助化疗作用仍未明了。本研究拟探讨多种基因表达对可手术ⅢA期NSCLC新辅助化疗疗效的预测作用。方法在对比ⅢA期NSCLC新辅助化疗与单纯手术疗效的前瞻性随机对照研究中,同期采用免疫组化法,检测抑癌基因p53,癌基因K-ras、HER2,血管内皮生长因子(vascularendothelialgrowthfactor,VEGF),表皮生长因子受体(epidermalgrowthfactorreceptor,EGFR),粘连因子CD44,金属蛋白酶-9(matrixmetalloproteinase-9,MMP-9)等蛋白表达。结果新辅助化疗组与单纯手术组的高基因表达率为58.3%比40.6%(P=0.145)。在新辅助化疗患者,组织学病理缓解有效与无效组两年无病生存率及生存期均无显著性差异(P=0.903,P=0.238);高基因表达与病理有效率亦无相关性(P=0.862);高基因与低基因表达组患者的平均无疾病生存分别为(14.1±9.8)月和(27.2±13.6)月(P=0.032),两年无疾病生存率分别为38.1%比46.7%(P=0.607),两组生存曲线出现明显分离,(P=0.093)。结论新辅助化疗患者的高基因表达预示术后更易发生远处转移,对这些患者是否术后加用化疗仍需进一步研究。     

Interleukin-10-deficient mice and inflammatory bowel disease associated cancer development

Interleukin-10-deficient mice develop colitis and colorectal cancer similar to the inflammatory bowel disease associated cancer in humans. The aim of this study was to identify possible mutations of oncogenes and tumour suppressor genes involved in tumorigenesis in Interleukin-10 (IL-10)-deficient mice. Twenty colon carcinomas from IL-10-deficient mice were screened for mutations in the K-ras and p53 genes by 'cold' single-strand-conformation polymorphism. Immunohistochemical staining was performed to detect mutations in the proteins P53, APC and MSH2, and the transforming growth factor beta type II receptor. Microsatellite instability was analysed at eight chromosomal loci and plasma levels of transforming growth factor beta1 (TGF-beta1) were also measured. At 9 weeks, 14% of the animals developed colorectal cancer, and at 10-31 weeks the incidence of carcinoma was 65%. No mutations were detected in the analysed oncogene and tumour suppressor genes. Plasma TGF-beta1 levels in IL-10-deficient mice 10-31 weeks old were higher than in wild-type littermates e.g. 45.7 +/- 4.6 ng/ml versus 19.8 +/- 4.5 ng/ml (P<0.01). No alterations in K-ras, p53, APC: and Msh2 genes suggests that other genes are involved in the development of these tumours. Elevated TGF-beta1 plasma levels correspond to the high incidence of dysplasia and cancer. Normal expression of the TGF-beta II receptors hints at genetic alterations in other members of the TGF-beta receptor signal transduction pathway.     

Increased expression of insulin-like growth factor I receptor in malignant cells expressing aberrant p53: functional impact

We investigated the functional impact of p53 on insulin-like growth factor I receptor (IGF-IR) expression in malignant cells. Using the BL-41tsp53-2 cell line, a transfectant carrying temperature-sensitive (ts) p53 and endogenous mutant p53 (codon 248), we demonstrated a drastic down-regulation of plasma membrane-bound IGF-IRs on induction of wild-type p53. However, a similar response was obtained by treatment of BL-41tsp53-2 cells expressing mutant ts p53 with a p53 antisense oligonucleotide. Thus, even if the negative effect of wild-type p53 predominates under a competitive condition, these data indicate that mutant p53 may be important for up-regulation of IGF-IR. To further elucidate this issue, three melanoma cell lines (BE, SK-MEL-5, and SK-MEL-28) that overexpressed p53 were investigated. The BE cell line has a "hot spot" mutation (codon 248) and expresses only codon 248-mutant p53. SK-MEL-28 has a point mutation at codon 145. SK-MEL-5 cells did not exhibit any p53 mutations, but the absence of p21Waf1 expression suggested functionally aberrant p53. Our data suggest that interaction with Mdm-2 may underlie p53 inactivation in these cells. Using p53 antisense oligonucleotides, we demonstrated a substantial down-regulation of cell surface expression of IGF-IR proteins in all melanoma cell lines after 24 h. This was paralleled by decreased tyrosine phosphorylation of IGF-IR and growth arrest, and, subsequently, massive cell death was observed (this was also seen in BL-41tsp53-2 cells with mutant conformation of ts p53). Taken together, our results suggest that up-regulation of IGF-IR as a result of expression of aberrant p53 may be important for the growth and survival of malignant cells.     

三氯乙烯药疹样皮炎病人外周血c-fos、c-myc、K-ras和p53 mRNA表达水平的研究

目的:探讨三氯乙烯(trichloroethylene,TCE)药疹样皮炎病人外周血癌基因c-fos、c-myc、K-ras、p53 mRNA表达水平的变化情况。方法:分别抽取4例健康人(对照组)及4例三氯乙烯致变态反应病人(病例组)抗凝外周全血,采用实时荧光定量PCR(real-time quantitative PCR)技术检测外周血中c-fos、c-myc、K-ras和p53 mRNA的表达水平。结果:与健康对照者比较,三氯乙烯药疹样皮炎病人外周血c-fos mRNA表达水平升高352%,c-myc mRNA升高41%,K-ras mRNA升高136%,p53 mRNA升高64%,两组间上述基因mRNA表达水平的差异均有统计学意义(P0.01或P0.05)。结论:三氯乙烯药疹样皮炎病人外周血癌基因表达水平增加,提示三氯乙烯可能有一定的致癌风险。