Identification of microRNAs 758 and 33b as potential modulators of ABCA1 expression in human atherosclerotic plaques.

BACKGROUND AND AIM: Adenosine triphosphate (ATP)-binding cassette (ABC) transporters A1 and G1 are the main transporters involved in macrophage cholesterol efflux. The understanding of the molecular mechanism(s) of their regulation in atherosclerosis is crucial for potential therapeutic approaches. Preclinical studies support a role for microRNAs in the posttranscriptional regulation of these transporters; however, no evidence is still available on human atherosclerosis. Thus, the aim of this study was to investigate the modulation of the ABCA1 and ABCG1 pathway in human atherosclerotic plaques and microRNA involvement in its modulation. METHODS AND RESULTS: Thirty-one human atherosclerotic plaques were obtained from patients undergoing carotid endarterectomy for high-grade (>70%) vessel stenosis, and divided into normocholesterolemic (n = 15) and hypercholesterolemic groups (n = 16) according to the presence/absence of hypercholesterolemia. Both ABCA1 and ABCG1 messenger RNAs (mRNAs) were significantly upregulated in carotid plaques from hypercholesterolemic patients as assessed by real-time polymerase chain reaction (RT-PCR). Despite this result, no difference was found at the protein levels analyzed by Western blot, thus suggesting a strong posttranscriptional modulation. MicroRNA microarray and subsequent validation by RT-PCR showed a significant upregulation of ABCA1-linked miR-758 and miR-33b in plaques from hypercholesterolemic patients. CONCLUSION: We provide evidence of a strong posttranscriptional regulation of ABCA1 and ABCG1 expression in human atherosclerotic plaques from hypercholesterolemic patients. This effect is potentially due to the concomitant increase of miR-33b and miR-758, two well-established regulators of ABCA1 and ABCG1 expression. The identification of miR-33b and miR-758 as putative key regulators of ABCA1 protein expression within human atherosclerotic plaques provides further data for the realization of new anti-atherosclerotic drugs with specific targets based on anti-miRNA technologies.

Activating c-KIT mutations in a subset of thymic carcinoma and response to different c-KIT inhibitors.

BACKGROUND: To analyze a multi-institutional series of type C thymic carcinomas (TCs) (including neuroendocrine tumors), focusing on the expression and mutations of c-KIT. MATERIALS AND METHODS: Immunohistochemical expression of c-KIT/CD117, p63, CD5 and neuroendocrine markers, as well as mutational analysis of c-KIT exons 9, 11, 13, 14, 17 by direct sequencing of 48 cases of TCs. Immunohistochemical and molecular data were statistically crossed with clinicopathological features. RESULTS: Overall, 29 tumors (60%) expressed CD117, 69% were positive for CD5 and 85% (41 cases) for p63. Neuroendocrine markers stained all six atypical carcinoids and five poorly-differentiated thymic squamous cell carcinomas. Overall, six CD117-positive cases (12.5%) showed c-KIT mutation. No mutation was detected in CD117-negative tumors and carcinoids. All the mutations were found in poorly-differentiated thymic squamous cell carcinomas expressing CD117, CD5, p63 and lacking neuroendocrine markers (6 of 12 cases with these features). Mutations involved exon 11 (four cases: V559A, L576P, Y553N, W557R), exon 9 (E490K) and exon 17 (D820E). CONCLUSIONS: All TCs need an immunohistochemical screening with CD117, while c-KIT mutation analysis is mandatory only in CD117-positive cases, particularly when coexpressing CD5 and p63, lacking neuroendocrine differentiation. The finding of c-KIT mutation can predict efficacy with different c-KIT inhibitors.

Predictive markers in lung cancer: a few hints for the practicing pathologist.

This review article highlights some important points in the evolving area of predictive biomarkers determination in non-small-cell lung cancer toward standardization of testing practices, including EGFR mutations, ALK and ROS1 rearrangements and immunohistochemical expression of PD-L1. Considerations for selecting appropriate populations for molecular testing, and emergence of other targetable molecular alterations are also discussed.

The effects of acute passive smoke exposure on endothelium-dependent brachial artery dilation in healthy individuals.

Passive smoking has both short-term and long-term vascular effects. It is not clear whether impairment of endothelial function reflects the acute effects of passive smoke exposure or the chronic effects. The purpose of this study was to assess the hypothesis that short-term exposure to passive smoke impairs endothelium-dependent vasodilation in healthy nonsmokers. Eighteen healthy young never smokers (12 men, 6 women) 21 to 55 years old (mean +/- SD: 34 +/-9 years) underwent ultrasonography measuring baseline brachial-artery diameter and brachial-artery diameter during hyperemia and after sublingual administration of nitroglycerin, twice: in a smoke-free environment, and then in the same environment polluted by 30 to 35 ppm carbon monoxide. Each subject served as his/her control. Carboxyhemoglobin was measured in blood samples of subjects tested. Mean value of carboxyhemoglobin was 0.6 +/-0.5% in a smoke-free environment and 1.4 +/- 0.5% in a smoking environment (p <0.02). Mean values of flow-mediated dilation (FMD) were 12.6% +/- 7.8% in a smoke-free environment versus 6.8 +/- 7.8% in a smoking environment (p <0.01). On the contrary, nitroglycerin-induced vasodilation did not show any statistical difference (21 +/- 9.8% versus 23 +/-1.4%). Finally, the increase of carboxyhemoglobin was related statistically to the impairment of flow-mediated dilation (r = 0.51; p <0.002). Passive smoking impaired flow-mediated vasodilation in healthy never smokers in a smoking environment. The impairment was strongly related to carboxyhemoglobin level.

Is transcutaneous oxygen and carbon dioxide monitoring indispensable in short- and long-term therapeutic management of non-reconstructable lower critical limb ischemia?

AIM: The aim of this study was to evaluate the capacity of transcutaneous partial pressure of O(2) (TCpO(2)) and CO(2) (TCpCO(2)) to predict clinical response to pharmacological treatment in short- and long-term follow-up of unreconstructable critical limb ischemia (CLI) treated with prostanoids; to suggest a diagnostic and therapeutic algorithm able to define the possibility of prostanoid therapy in unreconstructable CLI at high risk of limb loss. METHODS: Twenty-six consecutive patients with CLI (21 with distal trophic lesions, 31 symptomatic limbs) considered unreconstructable after peripheral angiography and with a history of type 2 diabetes mellitus underwent daily parenteral Iloprost treatment for 2-3 weeks. RESULTS: Transcutaneous gas-analytic monitoring (TGM) in non-reconstructable CLI treated with Iloprost divided patients into 2 groups: early responders (ER) with increased TcpO(2) and normalization of TcpCO2, and non responders (NR) with unchanged TcpO(2) and TcpCO(2) parameters. In the NR who underwent a second cycle of Iloprost within a few months of the first, TGM further divided the patients into another subgroup of late responders (LR) with TcpO(2) and TcpCO(2) similar to the ER group and a subgroup of NR, who, after pharmacological treatment failure, should undergo eventual surgical re-timing and/or spinal cord stimulation in a final attempt to save the limb. CONCLUSIONS: In the short-term follow-up of CLI, a marked reduction in supine/dependent TcpO(2) and a marked increase in supine TcpCO(2) at the symptomatic forefoot proved to be significant predictors of major amputation risk. In the long-term follow-up period, TGM showed that, in ER and in LR, the favourable effect of pharmacological therapy observed in the first 6 months will disappear over the next 6 months, suggesting an algorithm of 2- to 3-week cycles of prostanoid therapy repeated every year. In NR treated with surgical and/or alternative therapies who did not undergo major amputations, prolonged instrumental TGM will provide a constant evaluation of metabolic parameters, thus providing the possibility to save the limb with additional pharmacological therapy.

p53 mutations and histological type of invasive breast carcinoma.

A polymerase chain reaction-single strand conformation polymorphism assay was used to assess p53 mutations in 148 invasive breast carcinomas, selected on the basis of their histotype. They comprised 56 lobular, 47 ductal, 19 mucinous, 18 medullary, and 8 papillary carcinomas. The distribution of p53 mutations was significantly different (P = 0.006) in the histotypes examined: mutations were frequent in medullary (39%) and ductal (26%), less common in lobular (12%), and absent in mucinous and papillary carcinomas. The frequency of mutations in the exon 5 of the p53 gene was significantly higher in medullary carcinomas than in the other histotypes: 5 (63%) of the mutations found in exon 5 were observed in medullary carcinomas (P = 0.012). One hundred twenty-two tumors from the total were also examined by immunohistochemistry for p53 overexpression using antibody PAb 1801. A specific immunostaining in neoplastic cells was present in 12 tumors. A strong correlation (P < 0.001) was observed between p53 mutations and nuclear accumulation of the p53 protein: 10 tumors were scored positive for both p53 mutation and overexpression. However, in 9 cases having a mutated p53 gene we failed to find a positive immunoreaction. A significant association (P = 0.01) was present between mutations in the p53 gene and high proliferative activity of the tumors determined by immunohistochemistry with monoclonal antibody Ki-67. Moreover, a significantly higher expression of the Ki-67 antigen was found in medullary carcinomas compared to the other histotypes. Our findings indicate that in invasive breast carcinomas structural abnormalities of the p53 gene are mainly seen in medullary and ductal tumors and that the other histological types, especially those associated with a high level of differentiation and favorable prognosis, show a very low incidence of p53 mutations.

p53 alterations in non-small cell lung cancers correlate with metastatic involvement of hilar and mediastinal lymph nodes.

Alterations of p53 are one of the most common molecular changes found in all types of lung tumors, suggesting a crucial role for p53 in bronchial carcinogenesis. However, the prognostic significance of p53 abnormalities in lung cancer patients is still unclear. By using genetic and immunohistochemical methods we have found p53 alterations in 40 of 53 (75%) primary, resected non-small cell lung cancer. A strong association (P = 0.0015) was found between deletions on chromosome region 17p13.3 and p53 mutations suggesting that loss of the wild-type p53 allele might be necessary for tumorigenesis. Correlations to clinicopathological parameters showed that p53 alterations (structural aberration of the gene and/or nuclear accumulation of the protein) are significantly linked with metastatic involvement of hilar and mediastinal lymph nodes (P < 0.01). Since the latter are well established prognostic factors for non-small cell lung cancer, p53 aberrations may also be a predictor of tumor aggressiveness.

Association between cigarette smoking and FHIT gene alterations in lung cancer.

Epidemiologic data have strongly indicated that cigarette smoking is linked to the development of lung cancer. However, little is known of the molecular targets of carcinogens contained in tobacco smoke. To identify genetic lesions characteristic of tobacco damage, we undertook a molecular analysis of microsatellite alterations within the FHIT gene and FRA3B, as well as at an independent locus on chromosome 10, D10S197, in lung tumors from heavy smokers and in tumors from never smokers. Loss of heterozygosity affecting at least one locus of the FHIT gene was observed in 41 of 51 tumors in the smokers group (80%) but in only 9 of 40 tumors in nonsmokers (22%). The comparison between the frequency of losses in FHIT in smokers and nonsmokers was statistically significant (P = 0.0001), whereas no difference in loss of heterozygosity rate was observed at D10S197 locus. These findings suggest that FHIT is a candidate molecular target of carcinogens contained in tobacco smoke.

p21 RNA and protein expression in non-small cell lung carcinomas: evidence of p53-independent expression and association with tumoral differentiation.

p21, the product of the WAF1/CIP1/SDI1/mda-6 gene, is an inhibitor of cyclin-dependent kinases. In cell cultures p21 is induced by p53-dependent and p53-independent pathways by DNA damage and induction of differentiation. We investigated p21 RNA and immunohistochemical expression in 43 non-small cell lung carcinomas and corresponding normal lung samples previously investigated for p53 and WAF1 gene status and p53 protein expression. p21 RNA and protein expression in normal and neoplastic tissues were strictly associated (p-0.0001). In normal tissue p21 RNA was expressed at low levels and p21 immunoreactivity was seen in scattered differentiated bronchial, alveolar and stromal cells. In the majority of neoplasms p21 protein and RNA were expressed at higher levels than in the corresponding normal tissues: p21 overexpression was seen in 27 (63%) and 28 (65%) cases respectively. p21 was expressed independently from p53 gene/protein alterations. p21 overexpression was more frequent in well differentiated tumors (P=0.01 and P=0.022 for RNA and protein respectively), and p21 immunoreactivity was usually seen in foci of more pronounced differentiation. We conclude that p21 expression is related to tumor differentiation, and that p53-independent p21 expression is a common feature of in vivo neoplasms.

Telomerase activity as a prognostic indicator in stage I non-small cell lung cancer.

Patients with stage I non-small cell lung cancer (NSCLC) are typically treated with surgical resection alone. However, about one-third of such patients develop disease recurrence and die within 5 years after complete resection. The ability to predict recurrence could represent an important contribution to treatment planning. This study evaluates the presence of telomerase activity in tumor cells as a predictor of disease recurrence and cancer-related death after operation for stage I NSCLC patients. The activity of the telomerase enzyme was investigated by telomeric repeat amplification protocol (TRAP) in tumors and matching normal lung tissue samples obtained from 107 consecutive operable patients with pathological stage I NSCLC. Telomerase activity was detected in 66 (62%) of the 107 tumors examined and in none of the corresponding adjacent noncancerous lung tissue samples. Correlation with pathological parameters showed that telomerase activity was associated with histopathological grade (P = 0.0135) but not with tumor size or histological type. Univariate survival curves, estimated using the method of Kaplan and Meier, defined a significant association between telomerase activity and both disease-free survival (P = 0.0115) and overall survival (P = 0.0129). In multivariate analyses, performed by Cox's proportional hazards regression models, the presence of telomerase activity was the only strong predictor of disease-free survival (P = 0.0173) and overall survival (P = 0.0187). Our data indicate that telomerase activity can be an important prognostic factor that should be considered in future prospective trials of adjuvant therapy for high-risk stage I NSCLC patients.

Prognostic value of p21(WAF1) and p53 expression in breast carcinoma: an immunohistochemical study in 261 patients with long-term follow-up.

p21 protein (p21) inhibitor of cyclin-dependent kinases is a critical downstream effector in the p53-specific pathway of growth control and can also be induced by p53-independent pathways in relation to terminal differentiation. We investigated p21 immunoreactivity in 261 breast carcinomas (141 node negative and 120 node positive) with long-term follow-up (median, 73 months; range, 37-119). p21 was seen in 214 (82%) infiltrating tumors, staining was nuclear and heterogeneous, and the p21 labeling index ranged from 0 to 90%. Sixty-eight (32%) patients showed p21 overexpression (>10% of reactive tumor cells). p21 overexpression was associated with large tumor size, positive nodal status, high histological grade, and high mitotic count and was related to short disease-free survival (DFS) in the whole series of patients (P = 0.04), in the node-negative subgroup (P = 0.004), and in the group of patients who did not undergo systemic adjuvant therapy (P = 0.003). In patients treated with systemic adjuvant therapy, bivariate analysis of the combined p21 and p53 phenotypes showed that p21+/p53+ tumors were associated with long DFS and overall survival (OS), whereas p21-/p53+ tumors had the worst prognosis. In treated patients, multivariate analysis showed that the p21-/53+ phenotype was independently associated with short DFS and OS. Our present data support the hypothesis that p21/p53 heterogeneous expression may be of clinical relevance for the therapeutic response to chemotherapy/hormonotherapy. The p21-/p53+ phenotype could correspond to a situation where p53 overexpression really reflects complete abrogation of p53 function. These cases with disrupted p53 function should have impaired the G1 checkpoint and may not be able to activate the apoptotic cascade in response to DNA-damaging drugs.

Reduced expression of INT-6/eIF3-p48 in human tumors.

The int-6 gene, originally identified as a common integration site for the mouse mammary tumor virus (MMTV) in mouse mammary tumors, encodes the p48 component of the eukaryotic translation initiation factor-3 (eIF3-p48). Int-6/eIF3-p48 is expressed in all adult tissues which have been tested and early in embryonic development. Int-6/eIF3-p48 has been highly conserved throughout evolution and the deduced amino acid sequence of the human gene product is identical to the mouse protein. Viral insertions at the Int-6/eIF3-p48 locus in mouse mammary tumors result in production of chimeric Int-6/eIF3-p48/MMTV products that may act as dominant negative oncoproteins. Int-6/eIF3-p48 has also been identified as a human protein that binds to the human T-cell leukemia virus type I Tax oncoprotein. The role of Int-6/eIF3-p48 in human carcinogenesis is unknown at the present time. In this study we have examined Int-6/eIF3-p48 gene status and expression in two of the most common forms of cancer in humans, breast and lung tumors. Sixty-two breast carcinomas and 78 non-small cell lung carcinomas (NSCLC) were investigated. LOH at the Int-6/eIF3-p48 locus was observed in 5 (21%) of 24 informative breast tumors and 10 (29%) of 34 informative lung tumors. A reduced expression of Int-6/eIF3-p48 was seen in 23 (37%) of breast cancer samples and 24 (31%) of NSCLC samples. An association between Int-6/eIF3-p48 expression and LOH at the Int-6/eIF3-p48 locus was observed. Int-6/eIF3-p48 expression was not related to commonly used pathological parameters in breast cancer patients, while in NSCLC patients int-6/eIF3-p48 expression was mainly seen in adenocarcinomas (P<0.0001). In conclusion, our data show for the first time a decreased expression of Int-6/eIF3-p48 in a consistent portion of human breast and lung carcinomas, frequently associated with LOH at the Int-6/eIF3-p48 locus. Additional studies on larger series of tumor specimens with long-term follow-up are needed to determine whether Int-6/eIF3-p48 expression may represent a new prognostic or predictive marker.

P53 and C-erbb-2 alterations in in-situ and invasive ductal breast carcinomas - a genetic and immunohistochemical analysis.

p53 mutations, c-erbB-2 amplifications and expression of the related proteins were evaluated in a panel of ductal breast carcinomas selected on the basis of their invasive component. The tumors comprised: 8 ductal carcinomas in situ (DCIS); 8 carcinomas with a minimal (less than 20%) invasive component, hereafter referred to as DCIC (<20%); 13 carcinomas with 20%-50% invasiveness, DCIC (20-50%), and 48 infiltrating carcinomas with more than 50% invasive component, DCIC (>50%). Tumors were further subdivided into large pleomorphic cell type or small regular cell type. A strong association was present between p53 gene mutations and p53 protein overexpression (p<0.001) as well as between amplification of the c-erbB-2 gene and expression of its protein product (p=0.006). p53 aberrations (gene mutation and/or protein overexpression) were observed in 1 (12%) of 8 DCIS, 1 (11%) of 9 DCIC (<20%), 3 (23%) of 13 DCIC (20%-50%), and 13 (28%) of 47 DCIC (>50%). Amplification and/or overexpression of c-erbB-2 were found in 30 (39%) of the 77 breast carcinomas analyzed and were more frequent in DCIC (<20%) and in DCIC (20%-50%) (56% and 46% respectively) than in DCIS or DCIC (>50%) (12% and 38% respectively). Irrespective of the presence of invasion, tumors with p53 or c-erbB-2 alterations showed more frequently large cells with pleomorphic nuclei, (for p53, p=0.027; for c-erbB-2, p=0.014). Our data suggest that p53 and c-erbB-2 alerations may occur in the earliest recognized phase of breast cancer and may be important in the evolution of small cell to large cell mammary carcinoma during tumor progression.

Absence of somatic mutations in the coding region of the waf1/cip1 gene in human breast, lung and ovarian carcinomas - a polymorphism at codon-31.

Seventy-four invasive ductal, breast carcinomas, 73 non-small cell lung carcinomas and 36 ovarian adenocarcinomas, obtained from 183 unrelated patients, were investigated for mutations in the WAF1/CIP1 coding sequence by reverse transcriptase-polymerase chain reaction-single strand conformation polymorphism analysis. No somatic mutations were present in the WAF1/CIP1 open reading frame (ORF) in tumor samples. A polymorphism at codon 31 was observed in 16 (8.7%) cancer patients and in 9 (8.8%) of 102 unrelated normal individuals. The polymorphic allele changes the codon 31 AGC to AGA, thus implying an aminoacid substitution from serine to arginine, and creates a Hga-1 restriction site which might be useful for deletion studies. The polymorphism was present in the heterozygous state, except for the case of a 70-year-old male lung cancer patient who was homozygous: Our results indicate that the coding region of WAF1/CIP1 is not a frequent target for somatic mutations in breast, lung and ovarian cancer.

Detection of p53 mutations by single-strand conformation polymorphisms (SSCP) gel electrophoresis. A comparative study of radioactive and nonradioactive silver-stained SSCP analysis.

p53 mutations are the most common genetic abnormality in humans tumors, but their clinical significance remains to be precisely elucidated. Conventional single-strand conformation polymorphism (SSCP) analysis, a well-established technique for detecting p53 mutations, uses radioactively labeled polymerase chain reaction (PCR) products, which migrate abnormally in the presence of mutations. We performed radioactive PCR-SSCP analysis in a series of 30 formalin-fixed, paraffin-embedded ovarian carcinomas and two cell lines (SW480 and Caov4) harboring known homozygous p53 mutations and compared the results with nonradioactive silver-stained SSCP. The purpose was to assess whether nonradioactive SSCP is suitable for detecting p53 mutations in a rapid, sensitive, cost-effective fashion, without the need of radioactive isotopes. We accomplished PCR amplification of p53 exons 5 through 8 in 26 carcinomas, and radioactive SSCP detected p53 mutations in 13 tumors; three mutations were localized in exon 5, six in exon 6, two in exon 7, and two in exon 8. All mutations were correctly identified with nonradioactive SSCP, except for one exon 8 mutation. To establish the sensitivity of nonradioactive SSCP, DNA samples of SW480 and Caov4 were mixed with increasing amounts (0-90%) of normal DNA and subjected to PCR-SSCP analysis. Mutations were detected until the concentration of SW480 and Caov4 was 15% and 10%, respectively, of the total sample. The results of our investigation demonstrate that nonradioactive silver-stained SSCP is a sensitive, rapid, and simple technique to detect p53 mutations, even in formalin-fixed tissues, and could be easily used to investigate large series of patients to assess the clinical significance of p53 mutations in human tumors.

mdm2 gene amplification and overexpression in non-small cell lung carcinomas with accumulation of the p53 protein in the absence of p53 gene mutations.

Fifty-three non-small cell lung carcinomas (NSCLC), previously investigated for p53 abnormalities, were studied to evaluate the status of the mdm2 gene by Southern and Northern blot analysis and expression of the mdm2 protein by immunohistochemistry with specific monoclonal antibodies. Amplification and overexpression of the mdm2 gene and nuclear accumulation of its protein product were observed in three (6%) of the NSCLC examined. All of the tumors having mdm2 abnormalities belonged to a subset of NSCLC characterized by a strong accumulation of the p53 protein in the absence of p53 gene mutations. Since mdm2 is capable of forming tight complexes with p53, possibly stabilizing it, our results suggest that this event may take place in a low percentage of NSCLC. Moreover, all of the mdm2-positive tumors were histologically classified as lung adenocarcinomas. This may indicate that the mdm2 gene is preferentially altered in this particular subtype of lung tumors.

Enriched SSCP: a highly sensitive method for the detection of unknown mutations. Application to the molecular diagnosis of lung cancer in sputum samples.

Detection of gene mutations by sensitive polymerase chain reaction (PCR)-based methods can allow to identify occult neoplastic cells in a great excess of nonmalignant cells. These molecular approaches have an enormous potential in terms of early diagnosis, detection of occult micrometastases of solid tumors, and minimal residual disease in patients with hematopoietic malignancies. Currently, the applications of such methods are limited, mainly because the high sensitivity required for the identification of rare mutated alleles can be achieved only in cases in which mutations occur in few specific codons of a gene or when the mutation is already known. No methods are available by which few alleles with unknown mutations in tumor genes can be recognized in a great excess of wild-type alleles. We have developed an extremely sensitive method, termed enriched single-strand conformational polymorphism (E-SSCP), which permits detection of a rare alleles with unknown mutations. The method is based on the observation that after a conventional SSCP analysis the vast majority of mutated bands migrate close to the wild-type bands. The area of the gel having the highest chance to hold mutated alleles is physically isolated and is used as substrate for a second round of SSCP. Serially diluted DNA samples containing gene mutations demonstrated detection of 1 mutant/10(6) normal alleles. The E-SSCP assay was first applied to six sputum samples of patients affected by lung cancers with known p53 mutations showing in sputa the same mutations observed in tumors. The technique was then applied to eight cytologically negative sputum samples obtained from patients who later developed a clinically manifested lung carcinoma. In three cases, harboring a p53 mutation in tumor tissue, the E-SSCP analysis allowed the detection of the mutations in sputa months before clinical diagnosis. In conclusion, we have presented a general, highly sensitive technique for the detection of unknown mutations that may have several potential applications and may hold considerable promise for the early detection and study of cancer.

p53 nuclear accumulation in preneoplastic lesions and stage I uterine endometrioid adenocarcinoma.

A total of 118 endometrial neoplastic and preneoplastic lesions comprising 43 uterine endometrioid adenocarcinoma at stage I, 40 complex (adenomatous) hyperplasias and 35 atypical hyperplasias were examined for p53 nuclear accumulation to assess the incidence of p53 alterations in infiltrating carcinomas and to verify if p53 aberrations may allow the identification of a subset of premalignant cases with high risk of progression. No specific immunostaining was observed in the cases of complex hyperplasia without atypias. One (3%) of 35 atypical hyperplasias showed focal areas of p53 immuno-reactivity. The overall frequency of p53 overexpression in endometrial carcinomas was 54%. The distribution of cases with nuclear accumulation of p53 was significantly different (p=0.01) in tumours with different degree of invasiveness. In addition, p53 nuclear accumulation was observed more often in tumours with moderate (G2) or poor differentiation (G3) (p=0.03). Our data indicate that p53 aberrations are not early events in endometrial carcinogenesis and may be related with tumour progression and aggressiveness.

Lung tumours from non-smoking subjects: A p53-related genetic instability in a subset of cases.

Tumours developed in non-smoking patients represent about 10% of all lung neoplasms and show peculiar morphologic and genetic features. In a previous study, we found a constant association between p53 gene alterations and loss of heterozygosity (LOH) at the FHIT locus in a subset of non-smoking tumours (7 cases out of 35 analyzed), so we hypothesized that a genomic instability associated with p53 mutations could be the cause of FHIT LOH in these neoplasms. To test this hypothesis, in the same panel of tumours, we investigated the presence of LOH at 7 other microsatellite loci located on different chromosomes. Interestingly we found that all of the tumours with p53 alterations and LOH at the FHIT locus showed loss of heterozygosity at all of the informative tested loci. This association was statistically significant (p=0.0001). Our data indicate the presence of a generalized genomic instability in this subset of lung tumours. Since p53 alterations were mostly G:C --> A:T transitions and frameshift deletions, we are tempted to hypothesize that the genomic instability observed in non-smoking patients could be caused by particular p53 alterations. In fact, other kind of p53 mutations (G:C --> T:A transversions), frequently found in a series of 35 tumours of smokers used as control, were not associated with LOH at microsatellites loci. However, we cannot exclude that p53 alterations are a consequence and not the cause of the genomic instability. In this case, we have to admit that a gene(s), upstream of p53, is implicated in genome destabilisation in a subset of lung adenocarcinomas developed in non-smoking patients.

Multidrug resistance related genes and p53 expression in human non small cell lung cancer.

BACKGROUND: Many genes (mdr1, mrp, DNA topoisomerases II) are known to be involved in the resistance to unrelated drugs (the MDR phenomenon), but the mechanisms of their activation have to be further investigated. MATERIALS AND METHODS: Because several authors showed that p53 mutated gene was able to induce mdr1 overexpression, we evaluated in 51 non small cell lung cancer samples, already tested for p53 mutations, the expression of mdr1, mrp, DNA topoisomerase II alpha and beta mRNAs by qualitative RT-PCR assays. RESULTS: Mutations of p53 were found in 56% of cases. Mdr1 expression was detected in 27%, mrp in 100%, topoisomerase alpha in 82% and beta in 94% of the samples. CONCLUSIONS: It was not possible to detect any relationship between the expression of the MDR-related genes and tumor histological type, stage or lymph node involvement. Nevertheless, a close association between p53 alterations and either mdr1 gene (p = 0.001) or DNA topoisomerase II alpha (p = 0.003) expression was found.