MDM2 Overexpression with Alteration of the p53 Protein and Gene Status in Oral Carcinogenesis

In this study, to better understand the mechanism of oral squamous cell carcinoma (SCC) carcinogenesis, alterations of the p53 gene and overexpression of MDM2 and p53 were analyzed in 38 oral SCC samples. Twelve of the 38 specimens revealed mutant-type p53. Moreover, coexpression of MDM2 and p53 was found most frequently in dysplastic lesions ( P < 0.05). Expression of MDM2 and p53 was significantly increased in accordance with the histological progression of multistep carcinogenesis ( P < 0.05). No significant correlation was found between the expression of MDM2 and the alteration of p53 protein or p53 gene status. MDM2 overexpression with mutant p53 was significantly associated with poorly differentiated SCCs ( P < 0.05) and tumor stages III and IV of oral SCCs ( P < 0.05). These results suggest that MDM2 overexpression is an early event in oral carcinogenesis through the functional inactivation of the wild-type p53 , and corresponding alterations of MDM2 and p53 contribute to the oral carcinogenesis. We propose that it would be clinically more instructive to evaluate MDM2 overexpression combined with p53 gene status, compared to the evaluation of either MDM2 or p53 alteration alone.     

皮肤鳞状细胞癌FHIT基因的异常改变及意义

目的检测脆性组氨酸三联体基因在皮肤SCC中外显子5和8的缺失和突变情况,分析该异常在皮肤SCC发生中的作用机制。方法PCR-SSCP方法检测皮肤SCC患者皮损FHIT基因外显子5和8的缺失和突变状况。结果10例CSCC组织中,E5有3例缺失,E8有8例缺失,其中有2例同时缺失E5和E8,对扩出的外显子进行SSCP分析没有检测到其突变。结论皮肤SCC中存在外显子5和8的缺失异常,没有发现其突变,这种异常与该肿瘤的发生可能有关,其具体的发生机制需做更进一步的探讨。     

MDM2 overexpression with alteration of the p53 protein and gene status in oral carcinogenesis.

In this study, to better understand the mechanism of oral squamous cell carcinoma (SCC) carcinogenesis, alterations of the p53 gene and overexpression of MDM2 and p53 were analyzed in 38 oral SCC samples. Twelve of the 38 specimens revealed mutant-type p53. Moreover, coexpression of MDM2 and p53 was found most frequently in dysplastic lesions (P < 0.05). Expression of MDM2 and p53 was significantly increased in accordance with the histological progression of multistep carcinogenesis (P < 0.05). No significant correlation was found between the expression of MDM2 and the alteration of p53 protein or p53 gene status. MDM2 overexpression with mutant p53 was significantly associated with poorly differentiated SCCs (P < 0.05) and tumor stages III and IV of oral SCCs (P < 0.05). These results suggest that MDM2 overexpression is an early event in oral carcinogenesis through the functional inactivation of the wild-type p53, and corresponding alterations of MDM2 and p53 contribute to the oral carcinogenesis. We propose that it would be clinically more instructive to evaluate MDM2 overexpression combined with p53 gene status, compared to the evaluation of either MDM2 or p53 alteration alone.     

结晶型NiS诱发恶性转化细胞中的p16基因和FHIT基因的变化

目的 检测结晶型NiS诱发永生化人支气管上皮细胞系(16HBE)恶性转化过程中脆性组氨酸三联体基因(FHIT)和p16基因的变化,探讨镍化合物致癌的分子机制。方法 采用RT-PCR、DNA序列分析、银染PCR—SSCP方法检测恶性转化细胞、成瘤细胞中FHIT基因和p16基因的变化。结果 与对照组16HBE相比,转化细胞、成瘤细胞p16基因第2外显子、第2-3外显子末见突变,mRNA表达末见异常;FHIT基因第5,6,7,8外显子及第1-4外显子、第5-9外显子末见突变,但发现转化细胞、成瘤细胞FHIT基因的mRNA失表达或出现异常转录本;对其中FHIT基因第5-9外显子的一异常转录本测序分析显示,FHIT第6,7,8外显子缺失,第5,9外显子异常拼接,且中间插入一个36bp的小片段。结论 在结晶型NiS诱发16HBE恶性转化过程中,p16基因在DNA和mRNA水平末见异常改变,提示p16基因在镍致癌过程中可能不发挥作用;FHIT基因在mRNA水平出现缺失或异常转录本,表明FHIT基因在镍致癌过程中可能发挥一定作用;镍诱导的FHIT基因异常,可能是将外源致癌物、染色体脆性部位不稳定性和细胞恶变相联系起来的一个分子事件,FHIT基因可能是镍等外源致癌物作用的主要靶基因之一。     

肺癌组织和转移性肺门淋巴结中FHIT基因和p16基因的变化

目的 研究肺癌组织和转移性肺门淋巴结中组氨酸三联体基因和Ｐ１６基因的突变方法 采用ＲＴ－ＰＣＲ和ＲＴ－ＰＣＲ－ＳＳＣＰ方法对４９例肺 １６例相应的转移性肺门淋巴结进行Ｐ１６基因和ＦＨＩＴ基因检测,其中２例肺癌组织仅行Ｐ１６基因检测。结果 ３２例（６８．１％）肺癌原发灶（包括２例肺鳞状细胞原位癌）和１５例（９３．８％）转移性肺门淋巴结出现ＦＨＩＴ转录本缺失,二者失率相比,差异有显著性。ＦＨＩＴ基因转     

FHIT基因与喉癌相关性的研究

目的 研究ＦＨＩＴ基因在喉癌发生中的作用。方法 应用ＲＴ－ＰＣＲ技术筛查了喉细胞系Ｈｅｐ－２，宫颈癌细胞系ＨｅＬａ和２０例原发性喉癌的ＦＨＩＴ基因转录本，对其中的２例异常转录本进行了测序分析。同时，对另外６０例原发性喉癌ＦＨＩＴ基因进行了微卫星多态分析。结果 在２０例喉癌中，１４例，显示ＦＨＩＴ基因异常转录本，Ｈｅｐ－２和ＨｅＬａ细胞系ＦＨＴ基因转录本均存在缺失。     

FHIT基因在肺癌中的缺失与HPV感染的研究

目的　探讨肺癌发生的分子生物学机制。方法　采用逆转录 -巢式聚合酶链反应 (reverse tapepolymerasechainreaction)的方法对 42例肺癌及 10例正常肺组织中的FHIT(Fragilehistidinetriad)基因的缺失情况进行检测 ,并用PCR技术检测了肺癌组织中人乳头状瘤病毒 (humanpapillomavirus ,HPV)的DNA片段。 结果　 66.7% (2 8/4 2 )肺癌组织中检测到FHIT基因的缺失 ,而正常组织中未检测到FHIT基因的缺失 ,二者差别有显著意义 (P <0 .0 1)。 42例肺癌组织中有 8例检测到HPV的片段 ,阳性率为 19% (8/4 2 ) ,正常组织中未检测到HPV的片段 ,且在 8例HPV阳性的标本中均有FHIT基因缺失。结论　 (1)FHIT基因的缺失在肺癌的发生中起一定的作用。 (2 )FHIT基因的缺失与肺癌的不同病理分型、分化程度、临床分期无关。与吸烟有一定的相关性。 (3 )HPV的感染与肺癌的发生有一定关系 ,且与FHIT基因缺失有正相关关系。     

Clinicopathological significance of the fragile histidine triad transcription protein expression in laryngeal carcinogenesis

The fragile histidine triad (FHIT), frequently lost in many cancers, was identified as a candidate tumor suppressor gene at chromosome 3p locus 14.2. Loss of the FHIT protein because of the alteration or loss of heterozygosity by genetic deletion occurs in a variety of epithelial tumors including head and neck cancer. However, the biological function of the FHIT protein is still unknown and its role in intrinsic cellular proliferation remains particularly controversial in preinvasive lesions and invasive tumors of the head and neck. To clarify the role of the FHIT protein in laryngeal squamous cell carcinoma (LSCC) and to examine whether the expression of FHIT could be a prognostic parameter for laryngeal carcinogenesis, we investigated the relationship between the expression of the FHIT protein, other tumor suppressor gene products (p53 and p16), the cellular proliferation marker (Ki-67) and the survival time of patients with LSCC. In our study, there were significant differences (p<0.05) in the expression of FHIT between low grade dysplasia and LSCC. Additionally, survival time analysis showed a significant correlation between the reduction of FHIT expression and the length of disease-free survival (p<0.05) in patients with T1-T2 N0 laryngeal carcinoma. However, we did not confirm a relationship between the expression of FHIT, the other tumor suppressor gene products (p53 and p16) or the cellular proliferation marker (Ki-67). In conclusion, we provided evidence that the reduction of FHIT levels may be a useful prognostic indicator for the clinical outcome of laryngeal SCC. Our findings indicated that FHIT utilizes a pathway independent of p53 and is involved in abnormal cell proliferation via the breakdown of G0-G1 arrest in the larynx and apoptosis during multistep carcinogenesis of the larynx.     

The p53 status of cultured human premalignant oral keratinocytes.

Around 60% of oral squamous cell carcinomas (SCCs) have been shown to harbour p53 mutations, and other studies have demonstrated mutant p53 genes in normal and dysplastic squamous epithelium adjacent to these SCCs. In line with these earlier studies we show here that DOK, a keratinocyte cell line derived from a dysplasia, displays elevated levels of p53 protein and harbours a 12 bp in-frame deletion of the p53 gene spanning codons 188-191. In contrast, the coding region of the p53 gene was normal in a series of six benign recurrent laryngeal papillomas and a series of four premalignant oral erythroplakia biopsies and their cell cultures. All but one of these lesions were free of malignancy at the time of biopsy, in contrast to the premalignant lesions studied by previous investigators, but keratinocytes cultured from these lesions all displayed a partially transformed phenotype that was less pronounced than that of DOK. Since three out of four of the erythroplakia patients developed SCC within 1 year of biopsy, these lesions were by definition premalignant. The availability of strains of partially transformed keratinocytes from premalignant erythroplakias which possess normal p53 genes should enable us to test the role of mutant p53 in the progression of erythroplakia to SCC. The premalignant tissues and cultures were also tested for the presence of human papillomavirus (HPV), which is known to inactivate p53 function in some cases. Only the benign papillomas were shown to contain high levels of either HPV 6 or HPV 11 E6 DNA, but not both, and none of the samples contained detectable levels of HPV 16, HPV 18 or HPV 33 E6 DNA or L1 DNA of several other HPV types. There was therefore no evidence to suggest that p53 was being inactivated by a highly oncogenic HPV in these samples.     

Fluorescence in situ hybridization for detecting genomic alterations of cyclin D1 and p16 in oral squamous cell carcinomas

BACKGROUND: Cyclin D1 (CCND1) and p16 alterations have been detected in oral squamous cell carcinomas (SCCs), suggesting that abnormalities of these genes may play an important role in the genesis or progression of oral SCCs and serve as independent prognostic indicators. The detection of CCND1 and p16 aberrations using a simple and sensitive method would be valuable for the development of effective treatment modalities for oral cancer. The objective of the current study was to determine whether CCND1 numerical aberrations and p16 deletions in oral SCCs detected by fluorescence in situ hybridization (FISH) have any impact on clinical outcome. METHODS: Using genomic DNA probes for CCND1 and p16, FISH was performed on specimens that were obtained by fine-needle aspiration (FNA) from 57 primary oral SCCs. RESULTS: The CCND1 numerical aberration was observed in 28 of 57 patients (49%) with oral SCCs and was associated significantly with reduced disease-free survival (P = .0004) and overall survival (P = .0179). Conversely, p16 deletion was detected in 22 of 57 patients (39%). The disease-free and overall survival rates for patients with p16 deletion were lower than those among patients without the p16 deletion, although the difference just failed to reach statistical significance (P = .0516 and P = .1878, respectively). The p16 deletion in the presence of the CCND1 numerical aberration conferred significantly worse disease-free survival (P = .0002) and overall survival (P = .0153). CONCLUSIONS: Although the CCND1 numerical aberration was a good predictor of aggressive tumors, recurrence, and poor prognosis in patients with oral SCCs, the authors were able to identify subgroups of patients that had early disease recurrence and a poor prognosis more efficiently by assessment of p16 deletion in addition to CCND1 genetic status using FISH on FNA biopsy samples compared with the analysis of either alteration alone.