Oncosuppressor proteins of fragile sites are reduced in cervical cancer

FHIT and WWOX are tumor suppressor genes that span the common fragile sites FRA3B and FRA16D, respectively. To analyze possible synergisms among these genes in cervical cancer progression, we considered 159 cervical intraepithelial neoplasias, and 58 invasive squamous cell carcinomas of the uterine cervix. All cases were previously selected as high risk HPV. FHIT and WWOX proteins were examined by immunohistochemistry and their expression was inversely correlated with precancerous vs. invasive lesions. Statistics among biological markers indicated an association between FHIT and WWOX. Protein expression of these two genes was also absent or reduced in cancer cell lines. Thus, WWOX may be considered as a novel important genetic marker in cervical cancer and the association between the altered expression of FHIT and WWOX may be a critical event in the progression of this neoplasia.     

The fragile histidine triad gene: a molecular link between cigarette smoking and cervical cancer.

PURPOSE: Smoking is an epidemiologic risk factor for cervical cancer. The fragile histidine triad (FHIT) gene is a tumor suppressor gene that is altered in 80% of tobacco-associated lung cancers. We hypothesized that reduced FHIT protein expression, homozygous deletions (HD) or hemizygous deletions (HemiD) and microsatellite alterations (MA) at the FHIT/FRA3B locus occur more commonly in cervical cancers of smokers than nonsmokers. EXPERIMENTAL DESIGN: Archival tissues of 58 patients with stage IA1 to IB2 squamous cell carcinoma of the cervix were identified. FHIT protein expression was studied with immunohistochemistry. Laser capture microdissection was used to isolate tumor and normal DNA. HD/HemiD of FHIT exons 4 and 5 were analyzed by monoplex real-time PCR. MA at FHIT/FRA3B were studied with multiplex nested PCR with three fluorescently labeled microsatellite markers (D3S1300, D3S1312, and D3S1480). RESULTS: Eighteen of 26 tumors from smokers (69%) and 13 of 32 nonsmokers (41%; P < 0.05) showed loss of FHIT protein expression. Thirty-seven stage IB tumors yielded sufficient DNA for analyses. HD or HemiD of both exons tested occurred in 8 of 17 smokers (47%) and 2 of 20 nonsmokers (10%; P < 0.05). MA at more than two sites were found in 11 of 17 tumors of smokers (65%) and 6 of 20 nonsmokers (30%; P < 0.05). Mean composite genomic FHIT alteration scores were significantly higher for tumors of smokers versus nonsmokers (0.67 versus 0.40; P < 0.02). CONCLUSION: Loss of FHIT expression, HD, HemiD, and MA at the FHIT/FRA3B locus occur significantly more commonly in cervical cancers of smokers. These findings suggest that the tumor suppressor gene FHIT may represent a molecular target in cigarette smoking-associated cervical carcinogenesis.     

Abnormal structure and expression of PTEN/MMAC1 gene in human uterine cancers

The PTEN/MMAC1 gene, located on human chromosome 10q23, has recently been implicated as a candidate tumor suppressor gene in human cancers. In the present study, 12 uterine cancer cell lines and 87 uterine cancers of various grades and histological type were analyzed for PTEN/MMAC1 gene. Three of 44 endometrial carcinoma (7%) showed no PTEN/MMAC1 mRNA expression by RT-PCR analysis. Sequencing analysis of entire coding region of PTEN/MMAC1 gene revealed mutations in three of six endometrial cancer cell lines (50%) and 17 of 44 endometrial cancer tissues (39%). In contrast, for cervical cancers, only one of six cancer cell lines (2%) showed mutation, and one of 43 cancer tissues (2%) had an abnormality. Overall, 36% of the abnormal spots were located in exon 5, 24% were in exon 8, 16% were in exon 3, and 8% were in exon 6, and single cases of abnormality were found in exons 1, 4, and 7. Our results revealed that, in total, 60% of abnormalities were clustered in exons 5 and 8. Exon 5 is a functional domain of the PEN/MMAC1 gene, and therefore, abnormalities in this region may be important for loss of PTEN/MMAC1 gene function. Finally, we found a high frequency of PTEN/MMAC1 gene abnormalities in endometrial carcinomas but a low frequency in cervical carcinomas. These findings suggest that disruption of PTEN/MMAC1 by mutation or absence of expression may contribute to the pathogenesis or neoplastic evolution in a large proportion of endometrial carcinomas but in a small proportion of cervical carcinomas.     

Telomerase activity in gynecological tumors

The aim of this study was to define the clinical implications of semi-quantitative telomerase activity in gynecological tumors by comparing the telomerase activity of cancerous lesion and the adjacent non-cancerous lesion. In 118 cases of gynecologic tumors, including 41 uterine cervical tumors, 43 uterine body tumors and 34 ovarian tumors, telomerase activities were determined using TRAPeze telomerase detection kit for the extension reaction of the telomere sequence and the PCR reaction for amplification of the sequence, and using fluorecence-based telomere repeat amplification protocol (F-TRAP) method for the detection. In all gynecologic cancers examined, telomerase activity of the cancerous lesion was significantly higher than that of the non-cancerous lesion. Telomerase activity in the uterine cervix increased in the following order of the normal uterine cervix, cervical dysplasia and cervical cancer. Regarding the endometrial cancer, telomerase activity at the primary lesion in patients with lymph node metastases was significantly higher than that in patients without lymph node metastases. When telomerase activity was compared by histologic subtypes of the ovarian cancer, clear cell adenocarcinoma showed significantly lower telomerase activity than the other subtypes, especially endometrioid adenocarcinoma. In all gynecologic cancers examined, there was no clear correlation between the telomerase activity and age at diagnosis or age of menopause. Although all tumors with 100 units or more telomerase activity were cancerous, the sensitivity was 39% in cervical cancer, 41% in endometrial cancer and 21% in ovarian cancer, respectively. Cervical intraepithelial neoplasia (CIN) had already increased telomerase activity and endometrial cancer with lymph node metastases had also greater activity than that without lymph node metastases. Although telomerase activity in ovarian cancer tended to increase as stage advances, it is noteworthy that clear cell adenocarcinoma showed significantly lower telomerase activity than endometrioid adenocarcinoma.     

Prospective Study of Antibody to Human Papilloma Virus type 16 and Risk of Cervical, Endometrial, and Ovarian Cancers (United States)

Objective: Human papilloma virus (HPV) is frequently detectable in cancers of the cervix, vagina, and vulva, but its role in endometrial and ovarian cancers is less certain. This analysis aimed to examine the association of presence of HPV type 16 (HPV-16) antibodies with subsequent risk of cervical, endometrial, and ovarian cancers. Methods: In a prospective study enrolling over 15,000 pregnant women, pre-cancer sera from women who developed cervical (n = 83), endometrial (n = 34), and ovarian (n = 35) cancers were compared with sera from 172 control women frequency-matched by age group and race. Results: HPV-16 seropositivity (OR = 2.0, 95% CI 1.0–3.4) was associated with cervical cancer, with the association more prominent for cancers occurring within 10 years of serum sampling (OR = 2.3, 95% CI 1.0–5.3) than cancers occurring later (OR = 1.6, 95% CI 0.75–3.6). Overall, the associations between HPV-16 seropositivity and endometrial (OR = 1.6, 95% CI 0.64–3.8) and ovarian cancers (OR = 1.1, 95% CI 0.43–2.8) were not significant, although the odds ratios for those cancers occurring within 20 years after serum sampling were similar to that for cervical cancer (OR = 2.2 for both). Conclusions: Our results confirm that HPV-16 infection precedes the development of cervical cancer. Predictability of HPV-16 seropositivity for risk of other female cancers warrants further investigation.     

Do FHIT gene alterations play a role in human solid tumors?

The fragile histidine triad (FHIT) gene encloses an active common chromosomal fragile site, FRA3B. This gene is known to be associated with genomic instability, apoptosis and DNA damage. FHIT disturbances have been related to carcinogenesis in different types of human tumor. Despite this, there are some controversies about the exact role of the FHIT gene in relation to tumor biology. Several pieces of evidence support the hypothesis that FHIT acts as a tumor suppressor gene. A loss or decrease in the Fhit protein expression appears to be related to tumor progression, poor prognostic factors and lower survival rates. The most frequent causes of FHIT expression changes are gene mutations, epigenetic alteration and loss of heterozygosity. This literature review aims to clarify the involvement of the FHIT gene in carcinogenesis, tumor progression and clinical outcome in prevalent solid malignancies, such as breast, lung, cervical, esophageal, gastric and colorectal cancers.     

PIK3CA gene mutations and amplifications in uterine cancers, identified by methods that avoid confounding by PIK3CA pseudogene sequences

PIK3CA codes for a Class IA p110-alpha catalytic subunit of the PI3Ks (phosphatidylinositol 3-kinases) that regulate various signaling pathways important for neoplasia, including cell proliferation, motility, adhesion, and survival. Pro-oncogenic mutations in exons 9 and 20 of the PIK3CA gene have been frequently observed in numerous types of human malignancies. Amplification of the PIK3CA gene has been reported in uterine cervical cancers. In this study, we have done in depth analysis of uterine cervical and endometrial cancers for PIK3CA gene mutations and amplifications. In uterine cervical cancers, PIK3CA mutations were found in 3 of 22 cases (14%), all of them in exon 9. In endometrial cancers, a similar incidence of mutations was found, in 3 of 29 cases (10%), however they were all within exon 20. Amplification of the PIK3CA gene was also detected in 2 out of 22 (9%) cervical cancers and 3 out of 29 (10%) endometrial cancers. In this study, we were unable to find a clear association between PIK3CA mutations and gene amplifications, nor with tumor histological subtypes or staging. Mutations and amplifications of the PIK3CA gene are relatively infrequent in human cervical and endometrial cancers; however, PIK3CA gene alteration may still play a role in some subset of uterine cancers.     

Frequent FHIT gene loss of heterozygosity in human papillomavirus-infected non-smoking female lung cancer in Taiwan

The fragile histidine triad (FHIT), located in chromosome region 3p14.2, had been reported to be a frequent allele with loss of heterozygosity (LOH) in smoking lung cancer and HPV-associated cervical cancer. Additionally, FHIT LOH may act as a tumor suppressor gene to involve in smoking-related lung tumorigenesis and HPV-related cervical tumorigenesis, respectively. In our previous report, a high prevalence of HPV 16/18 infection has been observed in non-smoking female lung cancer patients, and thus it was speculated that HPV 16/18 infection may increase the LOH frequency of FHIT in female cases to implicate in lung tumorigenesis. In this study, 157 lung cancer patients were enrolled and subjected to FHIT LOH analysis with three microsatellite markers. As expected, the frequency of FHIT LOH in males, smokers, and squamous cell carcinomas lung cancer patients was significantly higher than that of their corresponding counterpart (P=0.020 for gender, P<0.001 for smoking status, and P=0.038 for tumor type). Interestingly, a correlation between HPV 16 infection and FHIT LOH was observed in female lung cancer cases. To be more specifically, FHIT LOH frequency was remarkably increased from 18% (6 of 33) in HPV 16 non-infected female cases to 46% (11 of 24) in HPV 16 infected cases. The higher frequency of FHIT LOH observed in HPV 16-infected female lung tumors suggested that the involvement of HPV infection in lung tumorigenesis may, at least in part, be mediated through FHIT LOH.     

Frequent aberration of the transforming growth factor‐β receptor II gene in cell lines but no apparent mutation in pre‐invasive and invasive carcinomas of the uterine cervix

The type II transforming growth factor‐β (TGF‐β) receptor (RII) gene located at 3p22 plays an important role in regulating growth and differentiation of epithelium, including that of the uterine cervix. Loss‐of‐function mutations of RII have frequently been found in gastrointestinal cancers, with a replication‐error (RER) phenotype characterized by the presence of microsatellite instability (MI). In this study, genomic PCR, SSCP and DNA sequencing were conducted to investigate the coding sequences of the RII gene in cell lines (n = 5) and tissues (n = 15) of squamous carcinomas of the uterine cervix. Intragenic deletions were noted in 2 of 5 cervical‐cancer cell lines (ME180 and HeLa cells). However, no mutation, other than DNA polymorphisms, was found in 15 cervical cancers with either alleleic loss at 3p22 (n = 11) or MI (n = 4). Further analysis of squamous intraepithelial lesions (SIL) with (n = 12) or without (n = 4) MI for the (A)₁₀ change, a prototypic mutation found in over 90% of RER‐positive colon cancers, also showed no aberration. Our study concludes that the RII gene is frequently disrupted in cervical‐cancer cell lines, but is rarely mutated in CC and SIL tissues, including those showing MI or alleleic loss at 3p22. The underlined mechanism of genomic instability in CC and SIL may thus differ from that of colorectal cancer. The allelic loss at 3p22‐24 in CC does not involve the coding sequence of the RII gene. The non‐coding sequence of RII or an unidentified gene may be responsible for it. Int. J. Cancer 80:506–510, 1999. © 1999 Wiley‐Liss, Inc.     

Analysis of the fragile histidine triad (FHIT) gene in lobular breast cancer

The fragile histidine triad (FHIT) gene is a candidate tumour suppressor gene in breast and other cancers. We investigated deletions within the FHIT gene in lobular breast cancer and found that 16% of cases showed loss of heterozygosity (LOH) within the gene. We compared LOH within FHIT in lobular and ductal breast tumours and found a significant association between LOH at FHIT and the ductal histological type (P<0.001). To determine whether genomic alteration of the FHIT gene in lobular breast cancer leads to Fhit inactivation we have assessed the level of Fhit expression by immunohistochemical detection and determined that 27% (15 of 55) consecutive sporadic lobular tumours showed negative or reduced Fhit expression. A significant association was found between LOH at the FHIT gene and reduced Fhit expression in lobular and ductal tumours (P=0.025 and P=0.001, respectively). Thus, genetic alterations within the FHIT gene, leading to loss of Fhit protein, may play an important role in the carcinogenesis of a significant number of sporadic lobular breast cancers, even though the apparent frequency of genomic alterations within the gene is lower than in ductal breast cancer.     

人非小细胞肺癌中FHIT基因转录本异常的研究

目的 探讨ＦＨＩＴ基因转录表达异常在人肺癌发生、发展中的作用。方法 ３应用ｎｅｓｔｅｄ ＲＴ－ＰＣＲ方法对３５例人非小细胞肺癌（ＮＳＣＬＣ）组织、癌旁组织和远癌肺组织。１０例肺良性病变肺组织以及４株肺癌细胞株中ＦＨＩＴ基因转录表达异常进行了研究。结果 ３５例肺癌中１４例肺癌组织存在ＦＨＩＴ转录表达异常,异常率为４０％;在这１４例癌组织转录本异常病例中,５例癌旁组织亦见转隶本异常（３５．７１％,５／