Loss of heterozygosity and microsatellite instability of the h-ras gene in cancer of the head and neck

H-ras oncogene is involved in a wide range of human tumours. Its involvement in head and neck cancer has been demonstrated at the level of overexpression whereas ras mutations in these cancers are rare in the Western world. In this study we explored the incidence of the loss of heterozygosity (LOH) and microsateliite instability (MI) of a hexanucleotide repeat located in intron 1 of the H-ras gene, in 33 carcinomas of the head and neck. Five of the 33 (15%) SCCHN exhibited instability of the hexanucleotide repeat and 4 of the 16 (25%) informative specimens demonstrated LOH in the H-ras locus. An association was found between LOH in the H-ras locus and lymph node metastasis. These results indicate genomic instability and LOH in the H-ras gene in head and neck cancer, providing further evidence for the involvment of the H-ras gene in this disease.

Detection of human cytomegalovirus and epstein-barr-virus by the polymerase chain-reaction in patients with Beta-thalassemia

Infections caused by Human Cytomegalovirus (HCMV) and Epstein-Barr virus (EBV) are common in multiple transfused patients, such as patients with beta-thalassaemia. The ability of the Polymerase Chain Reaction (PCR) to amplify HCMV and EBV DNA from blood and other samples makes this technique a valuable diagnostic tool for the detection of both viruses in the early stages of the infection. PCR was used for the amplification of a 435 bp region of the immediate early-1 (IE-1) gene of HCMV and a 375 bp sequence from the EcoRI B fragment of EBV genome. Blood samples from 80 patients with beta-thalassaemia were examined. HCMV was found in 14 and EBV in 12 patients. The results obtained confirm the implications of HCMV and EBV in the diagnosis of viral infections in multiple transfused patients as well as the importance of PCR technique as a valuable diagnostic tool.

Detection of human papilloma virus (HPV) and K-ras mutations in human lung carcinomas

The purpose of our study was to assess the prevalence and prognostic significance of HPV infection as well as K-ras codon 12 point mutations in lung cancer. Patients diagnosed with lung carcinoma between 1988 and 1992 (N=99) were selected. HPV detection and typing was performed by PCR from paraffin-embedded tissues, while mutations in codon 12 of K-ras gene were detected using the restriction fragment length polymorphism (RFLP) analysis. The prevalence of HPV infection was 15%, while K-ras codon 12 point mutations were found in 18% of the specimens examined. In 50% of the HPV-positive cases, K-ras gene mutation coexisted. HPV 18 was the most frequent type. No correlation was found between K-ras mutation and HPV infection with sex, age and clinical outcome of the patient, or the histological type and the differentiation grade of the tumor. An association was found between K-ms codon 12 point mutations and the stage of the tumor, occurring more frequently at stage III (p=0.037). Infection with potentially oncogenic HPV types could co-operate with K-ras gene activation in the progression of the disease, since K-ras activation by point mutations seems to be a late event in lung carcinogenesis.

Hpv detection in stained cytological cervical specimens and correlation with cytology and histology

It has been suggested that detection of high risk human papillomavirus (HPV) in low grade cervical intraepithelial neoplasia contributes to transition to high grade lesions and cancer. Currently, the PAP smear is the primary screening tool to identify women with cervical disease, specifically cervical intraepithelial neoplasia (GIN). In the present study we examined the utility of HPV detection and typing by PCR, in women with cytological and/or histological evidence of low grade squamous lesion (LGSL), using stained PAP cervical smears. HPV infection was confirmed in 21 out of the 31 (68%) specimens examined.

Detection of k-ras mutations in nonsmall cell lung-carcinoma

Forty-five non-small cell lung cancers (NSCLC) were examined for the presence of K-ras mutations in codon 12 using RFLP (restriction fragment length polymorphism) and ARMS (amplification refractory mutation system) assays. The RFLP analysis consisted of a PCR and subsequent digestion of the product with BstNI. Three adenocarcinomas and one adenosquamous carcinoma were shown to have mutations at codon 12. All of these samples were also examined using the ARMS assay for mutations at codon 12 and second base G to A transitions at codon 13 of the K-ras gene. The same four samples were confirmed to have a single base change in codon 12. No G to A transitions were found at codon 13. The four mutations were: one G to C transversion, one G to A transition and two G to T transversions. All mutations occurred at the second position of codon 12 as shown by the ARMS assay. Both of these techniques are rapid and reproducible for the identification of mutations in the K-ras gene and have potential for use in cancer diagnosis.

The presence of herpesviruses in pterygium

Pterygium is a chronic disease of unknown origin and pathogenesis. It is a vision threatening disease where surgical excision is effective. We examined surgically excised symptomatic pterygia for the presence of herpesviruses such as cytomegalovirus (CMV), herpes simplex virus (HSV) and Epstein-Barr virus (EBV) DNA using the polymerase chain reaction (PCR) technique. Samples of normal conjuctival tissue from limpus at 12 or 6 hours were excised in some of the eyes treated; they were used as controls. HSV DNA was detected in 9 and CMV DNA in 8 out of the 20 examined samples. In 3 out of the 20 examined samples both HSV and CMV DNA were detected whereas EBV DNA was not found in any of the examined samples. These results suggest that HSV and CMV may contribute to the pathogenesis of pterygium.

Analysis of h-ras, k-ras and N-ras genes for expression, mutation and amplification in laryngeal tumors

The levels of expression of the ras family genes, in 14 tumour specimens from squamous cell carcinomas of the larynx were analysed by reverse transcription-polymerase chain reaction. The H-ras was overexpressed in 12 (86%) samples, K-ras in 11 (78%) and N-ras in 8 (57%) samples. All tumours exhibited overexpression of at least one member of the I-as family. In addition, each member of the ras family was activated independently from the rest of the ras family genes. The incidence of amplification in the ms family genes was also analysed by differential PCR: K-rns was found amplified in 14% (2/14), N-ras in 7% (1/14) and H-ras in none of the samples tested. Amplification data exhibited no association with the expressional levels of the ras genes. Furthermore, we investigated the incidence of codon 12 point mutations in the ras family genes but no mutation was found. The present study indicates that overexpression of the ras family genes is important for the development of the disease and it is not associated with the amplification status of the genes. In addition, the differential regulation among the members of the ms family might play a role in the development of laryngeal tumours.

Mutational activation of k-ras oncogene in human breast-tumors

ras genes are thought to play an important role in human cancer since they have been found to be activated frequently in several types of human tumors. From preliminary studies it has been found however, that ras mutations are extremely rare in breast tumors and therefore it was of interest to examine the frequency of such mutations. In this study we examined 65 cases of primary breast carcinomas from paraffin blocks, for the presence of point mutations in codons 12 of the K-ras and H-ras genes. The polymerase chain reaction (PCR) technique was used to amplify a codon 12 containing 157 bp and a 312 bp region of the K-ras and the H-ras genes respectively, followed by restriction fragment length polymorphism (RFLP) analysis to identify the point mutations. Eight out of the 65 tumors (12.3%) were found to carry a K-ras mutation in codon 12 but none was found to carry a H-ras mutation. It is suggested that the mutational activation of the K-ras gene may be involved in the development of a small percentage of breast tumors.

Endometrial carcinoma in a breast cancer patient treated with tamoxifen

The use of tamoxifen for breast cancer therapy is linked to an increased danger of developing endometrial neoplasias in postmenopausal patients receiving the drug. Understanding the molecular mechanisms of the tumorigenic activity of tamoxifen may be of great prognostic and therapeutic significance. Our study suggests that tamoxifen treatment and alterations of the K-ras proto-oncogene may occur as parallel events in carcinogenesis of the endometrium.

Ras gene activation in human small intestinal tumors

Expression of the ras oncoprotein in thirteen human small intestinal tumors was investigated employing an immunohistochemical technique. The level of ras p21 was analysed using the monoclonal antibody Y13-259 and the biotin-streptavidin-peroxidace-DAB technique. Nine out of thirteen tumors including one hyperplastic - metaplastic polyp, one adenomatous and papillary polyp of the duodenum, one adenomatous polyp, one leiomyoma, one carcinoid, one lymphoma, one angiosarcoma of the jejunum, one leiomyosarcoma and one metastatic adenocarcinoma of the colon, were found to ''press the ras p21 oncoprotein at elevated levels, as compared to adjacent normal tissue. Whereas in one Brunner's gland adenoma of the duodenum, one neurilemoma, one adenocarcinoma of the small intestine and one metastatic adenocarcinoma of the colon expression of ras p21 was not elevated. The detection of H-ras mutations in codon 12 and K-ras mutations in codons 12 and 13 was also examined using the polymerase chain reaction technique. Four out of the thirteen small intestinal tumors examined possessed mutations of the H-ras gene in codon 12. These included the following, tumors: one Brunner's gland adenoma of the duodenum, one lymphoma, one leiomyo-sarcoma and one metastatic adenocarcinoma of the colon. This is the first demonstration of ras mutations in small intestinal tumors. None of the tumors had mutations in K-ras codons 12 or 13 (Gly-->Asp) It is suggested that the ras p21 oncoprotein may be involved in the pathogenesis and H-ras mutations and be a molecular genetic marker in small intestinal tumors.

Changes in fos/jun binding-activity on a negative regulatory element of C-myc during differentiation of mouse erythroleukemic cells

The binding activity of the AP-1 FOS/JUN complex to a negative regulatory element on the c-myc promoter was investigated and correlated with events characteristic of terminal differentiation of HMBA-induced mouse erythroleukemic cells. It is suggested that the altered AP-1 activity that was found upon induction of the erythroid differentiation may contribute to the late decline in c-myc mRNA.

TGF-beta 1 overexpression in breast cancer

TGF-beta 1 belongs to a family of pluripotent growth factors (TGF beta s) and has been implicated in the development and progression of human breast cancer. There are conflicting data though, suggesting that TGF-beta has the pontency both to promote and inhibit the progression of mammary neoplasia. We examined the expression of TGF-beta 1 mRNA in 24 breast carcinomas using the technique of the reverse transcription polymerase chain reaction (RT-PCR) to obtain quantitative results. Overexpression of TGF-beta 1 gene was found in 75% of the cases. We also correlated the overexpression of the TGF-beta 1 gene with clinicopathological parameters including histological grade, tumour cellularity, oestrogen receptor status (ER), progesterone receptor status (PR) and lymph node involvement. The results led us to the conclusion that the increasing ratio of overexpression related to the stage of cancer in an analogous way (P similar to 1). No significant association was identified between the ratio of overexpression and the grade, ER, PR, or lymph node involvement (r(s) = 0.5, 0.2, 0.1, 0.1 respectively; P < 0.0001) in all categories.

A primary cardiac leiomyosarcoma with mutation at H-ras codon 12

The presence of activating ras mutations in a cardiac leiomyosarcoma which occurred in the right atrium of the heart of a female patient was examined. The tumor had the appearance of leiomyosarcoma in rutine histopathological examination and the definite diagnosis was confirmed by a positive immunohistochemical reaction to smooth muscle actin. Molecular analysis by polymerase chain reaction (PCR) restriction fragment length polymorphism (RFLP) technique showed a point mutation of H-ras gene at codon 12. To the best of our knowledge, this is the first report describing ras gene mutation in a cardiac leiomyosarcoma implying a role for the ras oncogenes in the development of this tumor.

Relative expression of wild-type and activated ki-ras2 oncogene in colorectal carcinomas

A quantitative, competitive RT-PCR-RFLP assay was developed to detect and discriminate the expression of mutant versus wild-type alleles of the Ki-ras oncogene. The aim was to establish whether these alleles are differentially expressed in human malignant neoplasma, since experiments in vitro have shown stoichiometric representation and expression of ras genes does not necessarily engender a cancer phenotype. Sixteen primary colorectal carcinomas and two colorectal carcinoma xenografts, passed in immune-suppressed mice, were studied. Previous sequence analysis had established that 9 of the primary tumours and both xenografts had codon 12 Ki-ras mutations, 4 tumours had codon 13 mutations and 3 were wild-type controls. Wild-type and mutant Ki-ras were co-expressed in all the primary tumours, but the assay showed that stoichiometrically equivalent amounts of the two mRNA species were present in only one-third: in the others, mutant Ki-ras was overexpressed by around 30-60% relative to wild-type. The xenografts showed a similar range of values, despite their near-total lack of stroma. Ki-ras activation by point mutation is known to be involved in the early, adenoma phase of evolution of colorectal tumorigenesis, but these results show that differential expression of the mutant allele is common in carcinomas and may be associated with persisting growth advantage.

Specific recognition of a transcriptional element within the human h-ras protooncogene by the p53 tumor-suppressor

The nuclear phosphoprotein p53 is frequently inactivated in human cancer. Although it was previously classified as an oncoprotein, p53 has emerged as a tumor suppressor controlling cell cycle progression by regulating gene transcription. A major biochemical property of wild-type p53 is its ability to bind DNA in a sequence-specific manner. The human c-H-ras gene contains within its first intron sequences that partially match the p53 consensus binding site. We determined that these sequences represent a bona fide p53 element, since in vitro translated wild-type p53 recognized them with high affinity. Furthermore, wild-type p53 activated transcription from a reporter plasmid containing the c-H-ras element as an enhancer. These findings suggest that p53 regulates cellular growth by coordinate transcription of genes that suppress and promote cellular proliferation.

Binding of the glucocorticoid and estrogen-receptors to the human h-ras oncogene sequences

There is evidence that hormone regulation of cellular oncogenes plays an essential role in human cancer. The c-H-ras gene is implicated through both mutation and abnormal gene expression in many types of human cancer. Computer scanning of this gene has revealed two putative hormone response motifs: A possible Glucocorticoid Response Element (GRE) at position 1261 of the first intron of the H-ras1 gene and a putative Estrogen Response Element (ERE), at position 3007 of the fourth intron of the gene. In DNA binding assays, using the HeLa and LATK-cell lines, we showed specific binding of the corresponding receptors at both putative H-ras glucocorticoid and estrogen response sequences, suggesting that hormones could be contributing to H-ras transcriptional regulation through interaction with their corresponding Hormone Response Elements (HREs).

Ap-1 recognizes sequence elements on hiv-1 LTR in human epithelial tumor-cell lines

Investigation of the nucleotide sequence of the HIV-1 LTR showed the presence of four novel short DNA regions which are homologous to the recognition site for the cellular transcription factor AP-1. Four short oligonucleotide hybrids containing these potential AP-1 sites were constructed and used in gel retardation assays and in competition experiments in order to determine the role of the AP-L protein in the regulation of HIV-1 expression. The breast MDA MB 468 and cervical HeLa turner cell lines, which are known to overexpress the AP-1 protein were used in a gel retardation assay as a control to study the affinity of the AP-1 to synthesized oligonucleotide sequences. We have observed specific binding of nuclear factor AP-1 to three of these oligonucleotide hybrids. These results demonstrate the presence of three novel AP-1 binding sites on HIV-1 LTR, one of which was found within the TAR element and in the Tat protein binding region. Moreover, they suggest that AP-1 could be contributing to HIV-1 transcriptional regulation through its interaction with the AP-1 binding sites of HIV-1 LTR.

T24 h-ras gene-expression increases the activity of phosphoglycerate kinase, enolase and pyruvate-kinase and decreases the activity of adenosine-deaminase in fibroblast cells

We examined the possible implication of ras in the regulation of the activity of several metabolic enzymes by employing an inducible H-ras expression system (RFLSVrasLAP cell line), in which the addition of IPTG decreases the levels of ras p21 3-fold. We measured the activity of hexokinase (E.C. 2.7.1.1.), glucose phosphate isomerase (E.C. 5.3.1.9), phospho-fructokinase (E.C. 2.7.1.11), aldolase (E.C. 4.1.2.13), phosphoglycerate kinase (E.C. 2.7.2.3), enolase (E.C. 4.2.1.11), pyruvate kinase (E.C. 2.7.1.40), lactate dehydrogenase (E.C. 1.1.1.27), adenosine deaminase (E.C. 3.5.4.4) and purine nucleoside phosphorylase (E.C. 2.4.2.1) from cells grown in the presence and absence of IPTG. We found that the addition of IPTG to RFLSVrasLAP cells led to lower activity of phosphoglycerate kinase (p=0.004), enolase (p=0.027) and pyruvate kinase (p=0.031). Enolase mRNA levels were found to be increased in cells overexpressing either the normal or mutant H-ras. The total rate of glycolysis was not affected by H-ras expression indicating that the implication of H-ras in the activity of phosphoglycerate kinase, enolase and pyruvate kinase may be associated with glycolysis-independent functions of these enzymes. Adenosine deaminase activity was found to increase after IPTG addition (P=0.009), indicating also a possible role for H-ras in the control of the purine nucleotide salvage pathway.

Human papilloma virus (HPV) vaccination in childhood: challenges and perspectives

Vaccination against human papilloma virus (HPV) in childhood is a significant step forward in the reduction of HPV associated morbidity and mortality and a considerable scientific achievement. However, many challenges remain to be overcome if an effective HPV vaccine programme is to be successfully introduced worldwide. The aim of this review is to identify and summarize the new issues concerning HPV vaccination that have emerged since its introduction into clinical practice in school-aged girls. According to the literature, the overall impact of HPV vaccination on cervical cancer is unlikely to be apparent for the next decade. Cost-effectiveness is of particular importance, particularly in developing countries. Determining the age at which the vaccine should be administered, whether to include boys in addition to girls, the costs and the implications for cervical screening are issues that need to be addressed by conducting further research.

Lamivudine monotherapy in HBeAg-negative chronic hepatitis B: prediction of response-breakthrough and long-term clinical outcome

BACKGROUND

Factors that predict response and breakthrough phenomenon to lamivudine monotherapy in patients with HBeAg-negative chronic hepatitis B have not been well defined.

AIM

To determine pre-treatment and on treatment variables that predict initial response and breakthrough in patients with HBeAg-negative chronic hepatitis B receiving long-term lamivudine.

METHODS

Seventy-nine patients, with chronic HBeAg-negative hepatitis B, who received lamivudine for a median of 31 months were included in the study.

RESULTS

Initial virologic and biochemical response was observed in 73 (92%) and 70 (89%) patients, respectively, while 34 (47%) and 15 (21%) patients developed virological and biochemical breakthrough, respectively. High levels of necroinflammation in liver biopsy were associated with a higher probability of initial virological and biochemical response. Patients with pre-treatment serum hepatitis B virus DNA concentrations of more than 10(6) copies/mL were three times more likely to develop virologic breakthrough. Two patients died, one with baseline cirrhosis because of liver failure during biochemical breakthrough while the second death was liver and treatment unrelated.

CONCLUSIONS

In HBeAg-negative chronic hepatitis B, initial response to lamivudine therapy is associated with necroinflammation, while baseline serum hepatitis B virus DNA exceeding 10(6) copies/mL is a strong predictor for breakthrough because of drug-resistant mutations. Severe complications are uncommon and are associated with biochemical breakthrough and pre-existing cirrhosis.

Microsatellite DNA instability and loss of heterozygosity in bronchial asthma

Genetic alterations, such as loss of heterozygosity (LOH) or microsatellite instability (MI), have been reported in both malignant and benign disorders. In order to identify loci of deoxyribonucleic acid (DNA) mutation in asthma, MI and LOH were studied in sputum cells. DNA was extracted from cells in the sputum and blood cells of 22 patients with moderate asthma. Cells were analysed for MI and LOH using 18 polymorphic markers on chromosome 5q, 6p, 11q, 14q. Microsatellite analysis was also performed in six healthy subjects. None of the healthy individuals exhibited any genetic alteration. Genetic alterations were found in 16 of 22 asthmatic patients (73%). In total, 12 (54.5%) patients exhibited LOH only, one (4.5%) MI only, while three showed both MI and LOH. The highest incidence of LOH and MI was found on chromosome 14q. Mean immunoglobulin E and blood eosinophil levels were significantly higher in asthmatics with three or more genetic alterations. A high incidence of genetic alterations in the deoxyribonucleic acid of the sputum cells was found in asthmatic patients. Further studies are needed to identify the role of loss of heterozygosity and microsatellite instability in the investigation of genetic susceptibility of asthma and thus, in its pathogenesis.

Mutations of retinoblastoma gene (Rb-1) as a prognostic factor in children with acute leukemia and neuroblastoma

Rb-1 is a tumor suppressor gene encoding for a nuclear phosphoprotein acting as a cell cycle regulator, normally expressed in hematopoietic cells and more often inactivated by point mutations with predominance for exons 20-24. The aim of this study is to correlate the retinoblastoma-1 (Rb-1) gene mutations with the prognosis and progression of childhood acute leukemia and neuroblastoma. Bone marrow slides from 26 children with leukemia (18 acute lymphoblastic leukemia [ALL] and 8 acute myeloid leukemia [AML]) and 4 children with neuroblastoma were studied. Exons 20, 21, and 22 were amplified using the polymerase chain reaction technique. Single strand conformational polymorphism (SSCP) and heterodoublex analysis were performed to detect mutations. In ALL cases, two samples in exon 20 (11.11%), one in exon 21 (5.56%), and four in exon 22 (22.22%) had altered conformation. All but one of these cases were classified as high-risk leukemia patients who either relapsed or never achieved remission. Two of the AML cases who did not achieve remission and one of the neuroblastoma cases with concomitant bone marrow infiltration had altered conformation as well. The SSCP and heterodoublex analysis showed that all but one who did not belong to the high-risk group had the same altered conformation. These data suggest that Rb-1 gene could possibly be used as an independent prognostic factor for the acute leukemia of childhood and result in the intensification of chemotherapy. In solid tumors with bone marrow involvement it could play a role as a marker of aggressive disease.

Microsatellite DNA instability in COPD

STUDY OBJECTIVES

Cigarette smoking is the prime cause of COPD; however, only a few smokers develop the disease. In a previous study, we demonstrated that microsatellite DNA instability (MSI) is a detectable phenomenon in sputum cells of COPD patients. Therefore, we hypothesize that this genetic alteration may indicate susceptibility to COPD.

DESIGN

In order to investigate this hypothesis, we compared smokers who developed COPD with smokers who did not develop COPD (referred to as non-COPD smokers).

SETTING

Seven highly polymorphic microsatellite markers were targeted on the DNA of sputum cells and of WBCs.

PATIENTS AND PARTICIPANTS

We studied 60 non-COPD smokers and 59 severe COPD patients with a similar smoking history (mean +/- SD) of 48+/-25 and 54+/-33 pack-years, respectively (p = 0.77). Non-COPD smokers were tested once; COPD smokers were tested twice, with an interval of 24 months between tests.

RESULTS

MSI was detected in 14 COPD patients (24%) but in none of the non-COPD smokers. In 10 COPD patients, MSI was exhibited by one microsatellite marker; in the remaining 4 COPD patients, MSI was exhibited by two different alleles. The most commonly affected marker was THRA1 on chromosome 17 (43%). No significant differences were found between MSI-positive and MSI-negative COPD patients for clinical or laboratory parameters, survival, and development of lung cancer. No change in the microsatellite alleles was found between the tests performed with a 24-month interval.

CONCLUSIONS

This study demonstrated that MSI was found exclusively in the sputum cells of smokers with COPD. The results support the hypothesis that MSI could be part of the complex genetic basis of COPD, and it could be a marker of the genetic alteration caused by smoking that allows COPD to develop.

Detection of hepatitis C virus in sera and genotyping according to the 5' non-coding region

A reverse transcription (RT)-polymerase chain reaction (PCR) method was used for detection of the RNA of hepatitis C virus (HCV) in 120 samples of sera from Crete, which were positive for HCV-specific antibodies, by ELISA and Western blot analyses. A segment of 255 bp, located in the most conserved region of the HCV genome (the 5' untranslated region, 5' UTR), was amplified. For the identification of sequence variation from the HCV-1 strain, twenty of these samples were sequenced and compared to prototype strain (HCV-1) according to current genotypic classification. We were able to identify fourteen of the twenty as type 1a (i.e. similar to the prototype), two as type 1b, two as type 3a and two as type 4a. These findings generally agree with the geographic distribution of the already identified genotypes, though 3a type has not been reported previously in Crete (Greece).

SV40-transformation of embryonic human diploid fibroblasts results in multiple molecular changes

Attempts were made to identify the cellular and molecular changes associated with SV40-transformation of human fibroblasts, MRC-5. SV40-transformed human fibroblasts, MRC-5V1, displayed a polygonal to round morphology, grew slowly, had reduced plating efficiencies but high saturation densities. However, they could be propagated in low serum-containing medium and grew very efficiently in soft agar. These altered growth properties of MRC-5V1 suggested that SV40 induced changes in cell adhesion and growth factor requirements. Indeed, MRC-5V1 expressed markedly reduced levels of cellular fibronectin, high levels of tPA and the expression of procollagen alpha 2(I) and decorin were absent. Moreover, MRC-5V1 did not express HGF/SF, a paracrine effector of epithelial cells and expressed very low levels of EGF receptor. However, SV40 induced the expression of TGF alpha, one of the ligands of the EGF receptor, TGF beta 1 and TGF beta 2, all of which are associated with cellular transformation. Given the establishment of autocrine loops in MRC-5V1 and the fact that decorin interacts with fibronectin and collagens and negatively regulates the activity of TGF beta s, these changes could account for the altered growth and transformation properties of MRC-5V1. Several studies have provided a link between oncogenic transformation, transcriptional and translational control. SV40 markedly reduced the expression of junB but not c-jun in MRC-5V1 and the expression of EIF-4E and EF1 delta were not significantly affected. The data shows that SV40-transformation of human fibroblasts is associated with multiple genetic changes affecting the expression of genes involved in cell adhesion, signal transduction and transcription, hence suggesting the breakdown of several cellular control mechanisms.

Microsatellite instability in patients with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a relatively common disease, affecting mainly males in the western world. Although substantial data are available as regards the clinicopathological characterization of COPD, little is known of the molecular basis of the disease. In the present study we analysed the incidence of microsatellite instability (MI) in cytological specimens from patients with COPD. MI reflects increased mutational rate and is associated with decreased accuracy in the DNA repair, resulting in the accumulation of somatic mutations in cells manifesting this genetic alteration. Among 31 specimens tested, 7 (23%) exhibited MI in at least one among 6 microsatellite markers tested. 5 cases were affected in only one marker while the remaining two cases exhibited evidence of MI in two microsatellite markers. These data suggest that an elevated mutational rate as reflected by the increased incidence of MI is associated with the development of the disease.

Definition of a tumor suppressor gene locus on the short arm of chromosome 3 in squamous cell carcinoma of the head and neck by means of microsatellite markers

BACKGROUND

Tumor suppressor genes are important in the development of head and neck cancer. Using microsatellite markers that map close to the region 3p24-pter, we determined the frequency of allele loss close to this site with a view to narrowing the search for a putative tumor suppressor gene involved in the development of squamous cell carcinoma of the head and neck, which may facilitate future positional cloning techniques.

DESIGN

Laboratory-based project with tumor and normal specimens subjected to molecular genetic analysis. Tumor-normal tissue DNA pairs were analyzed for allelic imbalance and microsatellite instability on chromosome 3p in the region 3p24-pter by the polymerase chain reaction and microsatellite markers D3S1304, D3S656, D3S1252, D3S1293, THRB, and D3S1266.

SETTING

Molecular genetics and oncology research laboratory.

PATIENTS

Paired tumor-normal DNA samples were obtained from 46 patients with tumors of the head and neck.

MAIN OUTCOME MEASURES

Detection of loss of heterozygosity and microsatellite instability on chromosome 3 in the region 3p24-p25.1.

RESULTS

We found loss of heterozygosity with at least one marker in 48% of informative cases and loss of heterozygosity or microsatellite instability in 57% of informative cases. The minimal region of loss was found in the region bounded by D3S656 and D31293.

CONCLUSION

A putative tumor suppressor gene in head and neck cancer lies between D3S656 and D3S1293 in the 3p25.1 region.

Detection of herpesvirus-like DNA sequences in Mediterranean Kaposi's sarcoma

The aetiology of Kaposi's sarcoma remains obscure, however, epidemiological studies indicate that the disease possesses an infectious aetiology. Recent data revealed the presence of specific herpesvirus-like DNA sequences (KHSV) in all forms of Kaposi's sarcoma indicating that a novel virus may be the infectious agent which causes the disease. The aim of the present investigation was to assess the incidence of this herpesvirus-like DNA sequence in 28 Mediterranean Kaposi's sarcomas. DNA was extracted from formalin-fixed paraffin-embedded tissues and analysed by a sensitive PCR based assay. The KSHV specific DNA sequences were found in 22 of 28 (79%) cases suggesting a potential important role in the development of the disease.

Binding of wild-type and mutant forms of p53 protein from human tumors to a specific DNA-sequence of the first intron of the h-ras oncogene

p53 is the most frequent target for genetic alterations in a wide variety of human cancers. The product of the p53 tumor suppressor gene binds to DNA and activates transcription from promoters containing its consensus binding site. In the accompanying paper we have found that P53 tumor suppressor protein recognizes specifically a transcriptional element within the human H-ras protooncogene (Spandidos DA, et al, Int J Oncol 7: 1029-1034, 1995). We transfected Saos-2 cells, which are p53-null cells, with plasmids encoding for the wild type (wt) and for one 'hot spot' mutant (mt) of the p53 gene (H 273). Using the resulted nuclear extracts for gel retardation assays, we showed binding of both the wild-type and the mutant form of p53 to the H-ras DNA. Furthermore, using nuclear extracts from head and neck tumors and from adjacent normal tissues in gel retardation assays, we found binding of both the wild-type and the p53 mutant in the same responsive element of the H-ras oncogene. These experimental results suggest a direct role of p53 in regulation of H-ras. Identification of cellular proto-oncogenes as mediators of the transcriptional effects of wild-type and mutant forms of p53 gene, will be a step towards a better understanding of the role of oncogenes and once-suppressor genes in tumor promotion.

Expression of ras p21, p53 and c-erbB-2 in advanced breast cancer and response to first line hormonal therapy

Several oncogenes and tumour-suppressor genes have been identified that may have an important role in the development of human breast carcinoma. Furthermore, some of these gene alterations may be linked to the development of invasion and subsequent metastasis. Alterations in the expression of ras p21, p53 and c-erbB-2 have all been linked to tumours with rapid cellular proliferation, but the evidence that they are of prognostic importance in patients with breast cancer is conflicting. This study explores the relationship between expression of these oncoproteins and clinical outcome in 92 patients with either locally advanced or metastatic breast cancer treated with primary endocrine therapy. Specimens of the primary carcinoma were available for analysis of hormone receptor, Ki67 labelling index, epidermal growth factor receptor (EGFR), c-erbB-2, p53 and ras p21. Clinical response was measured according to UICC criteria after 6 months of treatment and all patients were followed for time to progression and overall survival. As shown previously, oestrogen receptor (ER) negativity, high Ki67 labelling index and EGFR overexpression were associated with a shorter time to progression and overall survival. However, no statistically significant relationship existed between expression of ras p21, p53 or c-erbB-2 and response to treatment, time to progression or overall survival. We conclude that staining for these three oncoproteins has no role in therapeutic decision-making in patients with advanced breast cancer. The negative finding implies that while abnormal expression of these genes may have an important role in the development of breast cancer, the variations in growth characteristics of advanced breast cancer may be influenced by other factors.

Instability at microsatellite sequences in spontaneously aborted human embryos provides evidence for a novel mechanism for recurrent miscarriages

Several factors have been proposed to confer a risk for abortion of the embryo. However, the aetiology of spontaneous abortions remains unclear. In the present study we investigated if an increased mutational rate occurs in the embryonic tissue and whether this phenomenon is associated with recurrent miscarriage. The mutational rate was assessed in 30 spontaneously aborted embryos using a bank of 8 highly polymorphic microsatellite markers, each one located on a different chromosome. The microsatellite sequences of DNA extracted from distal sites of each embryo were amplified by the polymerase chain reaction and the electrophoretic patterns were compared. Shifts in the mobility of the microsatellites indicating instability were scored for 12 among 30 (40%) specimens, thus suggesting that microsatellite instability (MI) is a relatively common feature of spontaneously aborted embryonic tissues. Association was found between instability and the absence of normal childbirth: 11 among 18 cases without a normal childbirth exhibited evidence of MI while only one among 12 cases with normal childbirth was positive for MI. Our results suggest that instability at microsatellite sequences which indicate decreased fidelity in DNA replication and repair are associated with the recurrent abortion of the embryo, particularly in cases without a normal childbirth.

Mutations of ras genes in human tumors (review)

Ras family genes (H-, K- and N-ras) are implicated in a wide range of human rumours. Mutations are a major activating mechanism for the ras family genes, mainly in codons 12, 13 and 61, resulting in their conversion from proto-oncogenes to activated oncogenes. The detection of mutant ras alleles in human tumours has been performed by several investigators in a wide range of tissues. The aim of our review was to summarize the data obtained from these studies and to investigate whether the presence of mutant ras alleles was associated with particular clinical parameters.

Detection of activating mutations in the ras family genes in cytological specimens from lung-tumors

Mutations in the ras family genes (K-ras mainly) represent a common event in lung tumorigenesis which is frequently associated with poor clinical outcome. In order to investigate whether K-ras mutations are detectable in cytological material obtained from patients with lung cancer, 37 cytological specimens (16 fine needle aspiration and 21 bronchoscopy) were assessed for codon 12 point mutations in the H-, K- and N-ras genes by combined polymerase chain reaction-restriction fragment length polymorphism. K-ras codon 12 point mutations were found in 8 out of 37 (22%) specimens while no mutations were found in the H-ras and N-ras genes. Mutations were found in 27% (3 out of 11) of adenocarcinomas while in squamous cell carcinomas the incidence of mutations was 18% (3 out of 17). In addition, a K-ras codon 12 point mutation was found in one (12%) among 8 small cell carcinomas and in the only Hodgkin's lymphoma with metastasis in the lung. Our results are in agreement with previous results that recognise high incidence of K-ras activation in lung carcinomas, and indicate that detection of mutant ras alleles is possible in cytological material.

Loss of heterozygosity on chromosome-8 in squamous-cell carcinomas of the head and neck

LOH studies provide evidence for the implication of novel TSGs in human tumours. The p arm of chromosome 8 has been reported to harbour tumour suppressor genes (TSGs) which are very likely to be involved in the development of colon, lung, bladder and hepatocellular carcinomas. In addition, the c-myc proto-oncogene which is located on the 8q arm, has been found to be overexpressed in SCCHN. In the present study we have investigated the incidence of loss of heterozygosity (LOH) in chromosome 8 in 37 tumour specimens of squamous cell carcinomas of the head and neck (SCCHN), using a bank of 11 polymorphic microsatellite markers. The aim of this work was to assess whether there was an 8p TSG(s) in SCCHN, as reported in other tumours and also to investigate whether other areas of chromosome 8 exhibit a high LOH. A relatively high incidence of LOH was found for the markers D8S87 (29%) on 8p12 and ANK1 (20%) on 8p21.2-p11. These two markers are located in the area in which TSG(s) for other cancers have been previously described. When the data on D8S87 and ANK1 were analyzed together it was found that 13/35 (37%) of the SCCHN specimens had a loss at one or other of these markers, thus indicating that a putative TSG(s) in this region may play a role in the development of the SCCHN. No correlation was found between the LOH data and any of the clinicopathological parameters. We also investigated the incidence of c-myc amplification in 144 SCCHN specimens but only 4% were found to have an amplified c-myc allele, thus indicating that the overexpression of c-myc in SCCHN was not the result of gene amplification.

Genetic determinants of feline leukemia virus-induced lymphoid tumors: patterns of proviral insertion and gene rearrangement

The genetic basis of feline leukemia virus (FeLV)-induced lymphoma was investigated in a series of 63 lymphoid tumors and tumor cell lines of presumptive T-cell origin. These were examined for virus-induced rearrangements of the c-myc, flvi-2 (bmi-1), fit-1, and pim-1 loci, for T-cell receptor (TCR) gene rearrangements, and for the presence of env recombinant FeLV (FeLV-B). The myc locus was most frequently affected in naturally occurring lymphomas (32%; n = 38) either by transduction (21%) or by proviral insertion (11%). Proviral insertions were also common at flvi-2 (24%). The two other loci were occupied in a smaller number of the naturally occurring tumors (fit-1, 8%; pim-1, 5%). Examination of the entire set of tumors showed that significant numbers were affected at two (19%) or three (5%) of the loci. Occupation of the fit-1 locus was observed most frequently in tumors induced by FeLV-myc strains, while flvi-2 insertions occurred with similar frequency in the presence or absence of obvious c-myc activation. These results suggest a hierarchy of mutational events in the genesis of feline T-cell lymphomas by FeLV and implicate insertion at fit-1 as a late progression step. The strongest links observed were with T-cell development, as monitored by rearrangement status of the TCR beta-chain gene, which was positively associated with activation of myc (P < 0.001), and with proviral insertion at flvi-2 (P = 0.02). This analysis also revealed a genetically distinct subset of thymic lymphomas with unrearranged TCR beta-chain genes in which the known target loci were involved very infrequently. The presence of env recombinant FeLV (FeLV-B) showed a negative correlation with proviral insertion at fit-1, possibly due to the rapid onset of these tumors. These results shed further light on the multistep process of FeLV leukemogenesis and the relationships between lymphoid cell maturation and susceptibility to FeLV transformation.

Genomic instability and loh at 2 polymorphic sites in the h-ras1 gene

Several repetitive elements have been associated with and identified in the surrounding region and within the human c-H-ras1 gene. The polymorphism exhibited by these sites provides valuable information regarding the function and structure of the H-ras gene. We have investigated two such polymorphic sites: i) a hexanucleotide microsatellite region (HRMS) within intron 1 of H-ras and ii) the VTR region at the 3' end of the gene. Comparison between normal and tumor tissues from 25 samples of bladder cancer revealed that 5 samples (20%) exhibited LOH at these polymorphic sites indicating that an allelic loss had occured at the H-ras locus. Furthermore, instability was detected in 4 cases at the hexanucleotide locus, while the VTR region was found unaffected. The two polymorphic sites are in a strong linkage disequilibrium in normal tissues, while in tumor tissues with genomic instability this linkage is altered, possibly leading to differential regulation of the H-ras. Also a previously reported allele at the HRMS locus was found to behave in a manner that preserves the linkage between the two polymorphic sites in normal tissues.

Detection of hsv, CMV and ebv by the polymerase chain-reaction technique in patients with inflammatory eye-diseases

Herpes simplex virus (HSV), cytomegalovirus (CMV) and Epstein-Barr virus (EBV) have been recognized as pathogenic agents of intraocular inflammatory conditions. The ability of the Polymerase Chain Reaction (PCR) technique to amplify HSV, CMV and EBV DNA from aqueous specimens makes this technique a valuable diagnostic tool for the detection of these viral pathogens in patients with ophthalmic lesions. We used PCR for the amplification of a 476 bp long sequence from the pol I gene of HSV genome, a 435 bp region of the immediate early-1 (IE-1) gene of CMV and a 375 bp sequence from the EcoRI B fragment of EBV genome. We examined 22 aqueous humour specimens from patients with uveitis and retinitis, inflammatory eye diseases, diagnosed clinically. We found HSV in 4 (18.2%), CMV in 6 (27.3%) and EBV in 1 (4.5%) out of the 22 examined patients. None of the 22 examined samples was found to be infected with more than one of the examined viral pathogens. These data confirm the implications of the members of Herpesvirus family in inflammatory inner eye diseases and the importance of PCR technique as a diagnostic tool in clinical virology.

A method to detect and quantitate the expression of normal versus mutant h-ras transcripts at codon-12

We describe a PCR based method for qualitative and quantitative analysis of the H-ras gene. For qualitative analysis the aim was to detect codon 12 point mutations at transcriptional and genomic levels by a non-radioactive RFLP assay. Quantitative analysis was achieved by constructing an internal competitor with the same primer site requirements and sequence homology to the H-ras1 gene. The internal control was cloned into an expression vector allowing quantification at the genomic as well as transcriptional level. Two cell lines harbouring normal and T24 H-ras1 respectively, were employed as controls for qualitative and quantitative analysis. Theoretical implications of competitive quantification are also evaluated for increased estimation efficiency.

Inducible h-ras gene-expression controlled by an allosterically regulated transactivator

Inducible promoters have been employed widely to control the transcription of specific genes and thus to elucidate their role. We constructed a plasmid in which three lac operator sequences and the SV40 early promoter were placed upstream of the T24 H-ras1 gene. This plasmid was co-introduced in rat fibroblasts with a plasmid coding for a fusion protein containing the DNA binding domain of the lac repressor protein and the transactivation domain VP16 from HSV1. In the clones derived from this co-transfection, the transcription of the exogenous H-ras1 gene is dependent on the interaction between the transactivator protein and the lac operators. Given that this interaction is inhibited by IPTG, such a cell line overexpresses the H-ras gene encoded protein ras p21 and the addition of isopropyl beta-D-thiogalactopyranoside (IPTG) into the culture medium diminishes overexpression. The decrease of ms expression levels after the addition of IPTG was confirmed by Western blot analysis and by quantitative Reverse Transcription PCR based on comparison of amplification levels between the target cellular H-ras1 gene transcript and an in vitro produced deletion mutant H-ras reference transcript.

Detection of ras gene-mutations and hpv in lesions of the human female reproductive-tract

Compatible with the epidemiology and natural history of cervical cancer and with experimental findings that HPV-immortalized nontumorigenic cells are similar to cervical carcinoma cells, in terms of the quantity and type of viral RNA expressed, it is believed that additional cellular genetic events are necessary for tumorigenic conversion. In the current study we detected codon 12 point mutations of the K-ras oncogene with an incidence of 28.2% in malignant lesions of the cervix, as well as HPV 1 8 at a higher rate than HPV16 (30.2% vs 27.9%) in genital lesions, by PCR and RFLP analysis. Codon 12 point mutations of K-, H- and N-ras were also found in benign lesions of the cervix, in endometrial and in ovarian carcinomas, although at a lower frequency. It is suggested that the mutationally activated ras oncogenes cooperate with HPV in the early stages of carcinogenesis of the human female reproductive tract.

Detection of human cytomegalovirus by the polymerase chain-reaction in immunosuppressed and immunocompromised patients

Infections caused by Human Cytomegalovirus (HCMV) are very common in patients who undergo immunosuppression or immunocompromisation. The techniques used for routine HCMV detection are time-consuming and lack specificity and sensitivity. The ability of the Polymerase Chain Reaction (PCR) to amplify HCMV DNA from clinical samples of the patients is a valuable diagnostic tool for the detection of HCMV in the early stages of the infection. We used a pair of primers to amplify a 435 bp region of the immediate early-1 gene, to detect HCMV DNA in clinical samples from patients at high risk for HCMV infection. We found HCMV in the following type of patients: 6 out of 20 in immunosuppressed, 11 out of 31 in immunocompromised, 5 out of 8 in pregnant women, 4 out of 25 in patients with high anti-CMV IgM and IgG titres, 1 out of 2 in patients with kidney failure, and 6 out of 14 in patients with opthalmic disorders. Sixty-seven specimens, which were found to be negative for CMV by the PCR technique, were used to inoculate human fibroblast monolayer cultures and PCR was performed to the DNA extracted from the cultured cells. Only in 1 out of the 67 cases HCMV DNA was detected.

Detection of epidermal growth-factor receptor and C-erbb-2 gene amplification in transitional-cell bladder-carcinoma using the differential PCR technique

Amplification of genes associated with cell control and differentiation is found in many human tumours and its detection may have important value in predicting tumour progression. In this study we examined 72 DNA samples extracted from paraffin-fixed formalin-embedded transitional cell carcinomas with a novel differential PCR technique that can detect variations in gene dosage using small amounts of tumour DNA. We have observed that this technique under certain conditions has many advantages over traditional gene analysis techniques. Our study revealed EGF-r and c-erbB-2 gene amplification in 2/72 (3%) and 11/72 (15%) bladder carcinomas, respectively. EGF-r gene was amplified in 2/24 (8%) grade III carcinomas while c-erbB-2 was amplified in 2/25 (8%) and 9/24 (37.5%) grade II and grade III carcinomas, respectively. All cases with EGF-r and c-erbB-2 gene increased copy number were classified as invasive on the basis of muscularis propia invasion. The association between c-erbB-2 amplification and tumour grade as well as stage of the carcinomas was statistically significant indicating direct linkage to bladder carcinoma progression, while the relationship between EGF-r gene amplification and the above mentioned parameters did not reach significance.