Algorithmic assessment of cellular senescence in experimental and clinical specimens.

The development of genetic tools allowed for the validation of the pro-aging and pro-disease functions of senescent cells in vivo. These discoveries prompted the development of senotherapies-pharmaceutical interventions aimed at interfering with the detrimental effect of senescent cells-that are now entering the clinical stage. However, unequivocal identification and examination of cellular senescence remains highly difficult because of the lack of universal and specific markers. Here, to overcome the limitation of measuring individual markers, we describe a detailed two-phase algorithmic assessment to quantify various senescence-associated parameters in the same specimen. In the first phase, we combine the measurement of lysosomal and proliferative features with the expression of general senescence-associated genes to validate the presence of senescent cells. In the second phase we measure the levels of pro-inflammatory markers for specification of the type of senescence. The protocol can help graduate-level basic scientists to improve the characterization of senescence-associated phenotypes and the identification of specific senescent subtypes. Moreover, it can serve as an important tool for the clinical validation of the role of senescent cells and the effectiveness of anti-senescence therapies.

The DNA damage checkpoint precedes activation of ARF in response to escalating oncogenic stress during tumorigenesis.

Oncogenic stimuli trigger the DNA damage response (DDR) and induction of the alternative reading frame (ARF) tumor suppressor, both of which can activate the p53 pathway and provide intrinsic barriers to tumor progression. However, the respective timeframes and signal thresholds for ARF induction and DDR activation during tumorigenesis remain elusive. Here, these issues were addressed by analyses of mouse models of urinary bladder, colon, pancreatic and skin premalignant and malignant lesions. Consistently, ARF expression occurred at a later stage of tumor progression than activation of the DDR or p16(INK4A), a tumor-suppressor gene overlapping with ARF. Analogous results were obtained in several human clinical settings, including early and progressive lesions of the urinary bladder, head and neck, skin and pancreas. Mechanistic analyses of epithelial and fibroblast cell models exposed to various oncogenes showed that the delayed upregulation of ARF reflected a requirement for a higher, transcriptionally based threshold of oncogenic stress, elicited by at least two oncogenic 'hits', compared with lower activation threshold for DDR. We propose that relative to DDR activation, ARF provides a complementary and delayed barrier to tumor development, responding to more robust stimuli of escalating oncogenic overload.

Specific lipofuscin staining as a novel biomarker to detect replicative and stress-induced senescence. A method applicable in cryo-preserved and archival tissues.

There is shortage of extensive clinicopathologic studies of cellular senescence because the most reliable senescence biomarker, the detection of Senescence-Associated-beta-galactosidase activity (SA-ß-gal), is inapplicable in archival material and requires snap-frozen tissues. We validated the histochemical Sudan-Black-B (SBB) specific stain of lipofuscin, an aggregate of oxidized proteins, lipids and metals, known to accumulate in aged tissues, as an additional reliable approach to detect senescent cells independently of sample preparation. We analyzed cellular systems in which senescence was triggered by replicative exhaustion or stressful stimuli, conditional knock-in mice producing precancerous lesions exhibiting senescence, and human preneoplastic lesions known to contain senescent cells. In the above settings we demonstrated co-localization of lipofuscin and SA-ß-gal in senescent cells in vitro and in vivo (cryo-preserved tissue), strongly supporting the candidacy of lipofuscin for a biomarker of cellular senescence. Furthermore, cryo-preserved tissues positive for SA-ß-gal were formalin-fixed, paraffin-embedded, and stained with SBB. The corresponding SA-ß-gal positive tissue areas stained specifically for lipofuscin by SBB, whereas tissues negative for SA-ß-gal were lipofuscin negative, validating the sensitivity and specificity of the SBB staining to visualize senescent cells in archival material. The latter unique property of SBB could be exploited in research on widely available retrospective tissue material.

Late prosthetic shoulder hemiarthroplasty after failed management of complex proximal humeral fractures.

Background. The purpose of this study was to report our experience with shoulder hemiarthroplasty in the context of old trauma. Methods. 33 patients with failed treatment for a complex proximal humeral fracture underwent prosthetic hemiarthroplasty. There were 15 men and 18 women with a mean age of 58.1 years. The average period from initial treatment was 14.9 months. Sequelae included 11 malunions, 4 nonunions, 15 cases with avascular necrosis (AVN) and 3 neglected posterior locked dislocations. Follow up investigation included radiological assessment and clinical evaluation using the Constant score and a visual analogue pain scale. Results. After a mean follow up of 82.5 months the median Constant score was 75.7 points, improved by 60% in comparison to preoperative values. Greater tuberosity displacement, large cuff tears and severe malunion were the factors most affected outcome. No cases of stem loosening or severe migration were noted. 60% of the patients were able to do activities up to shoulder level compared with 24% before reconstruction. Conclusions. Late shoulder hemiarthroplasty is technically difficult and the results are inferior to those reported for acute humeral head replacement, nonetheless remains a satisfactory reconstructive option when primary treatment fails.

The tumor suppressor gene ARF as a sensor of oxidative stress.

Oxidative stress as a result of either exogenous stimuli or cellular metabolism affects several cellular processes such as proliferation, apoptosis, cell death and senescence. Consequently, it is implicated in the pathogenesis of various human diseases like cancer, diabetes mellitus, atherosclerosis, neurodegenerative diseases and aging. Oxidative stress is implicated in carcinogenesis either by directly provoking DNA damage or through the regulation of intracellular signaling cascades. In both cases the cellular response to oxidative stress is determined by the cellular context. ARF, the alternative protein product of the CDKN2A locus has been recently recognized as a novel sensor of oxidative stress, in a ß-catenin and Hsp70-mediated manner. Since, improved understanding of cellular responses to oxidative stress may facilitate the design of novel antineoplastic regimens, we herein review the mechanisms by which oxidative stress promotes carcinogenesis, focusing on the role of ARF as a sensor of oxidative stress.

E2F-1 overexpression correlates with decreased proliferation and better prognosis in adenocarcinomas of Barrett oesophagus.

BACKGROUND: E2F-1 expression is positively associated with tumour growth in oesophageal squamous-cell carcinomas (OSCC), while it exhibits oncosuppressive features in colonic adenocarcinomas (AC). To date there are no data regarding E2F-1 expression and its relationship with tumour kinetics (proliferation, apoptosis) in adenocarcinomas that develop on Barrett oesophagus. AIM: As oesophageal adenocarcinomas occur almost exclusively in the metaplastic Barrett epithelium and the opposing E2F-1 behaviour seems to be cell and tissue-type dependent, we examined the manner in which E2F-1 acts in ACs of Barrett oesophagus. METHODS: We estimated the immunohistochemical expression of E2F-1, Ki-67, caspase-3 and p53 immunohistochemical status in 35 Barrett oesophagus ACs. RESULTS: E2F-1 immunopositivity correlated inversely with Ki-67, by semi-serial section and statistical analysis (p = 0.023, Spearman correlation). Semi-serial section analysis revealed a direct association between E2F-1 and caspase-3 staining. No correlation was found with p53 status. Cases with higher E2F-1 immunoexpression exhibited longer survival (p = 0.047, Cox-regression). CONCLUSIONS: E2F-1 expression was negatively related to tumour proliferation in ACs of Barrett oesophagus. Additionally, E2F-1 immunohistochemical status correlated positively with patient survival. These findings are opposite from those seen in OSCCs, suggesting that the tumour-suppressing E2F-1 behaviour in oesophageal adenocarcinomas is possibly due to the intestinal-type nature of the metaplastic Barrett mucosa.

Oncogene-induced replication stress preferentially targets common fragile sites in preneoplastic lesions. A genome-wide study.

Common fragile sites (CFSs) are regions of the genome prone to breakage by replication inhibitors (extrinsic replication stress). Recently, we and others observed that oncogene-induced replication stress (RS) induces DNA damage from the earliest stages of cancer. Our aim was to perform a genome-wide analysis in precancerous and cancerous experimental models to examine whether allelic imbalance occurs within CFSs. Subsequently, CFSs sequence characteristics were assessed. We used a growth-factor-induced human skin hyperplasia and a H-ras-induced mouse hyperplastic urothelium as preneoplastic models, along with an inducible U2OS-CDT1(Tet-ON) cancer cell line model, all bearing established oncogene-induced RS stimuli. Human DNA was analysed with Affymetrix SNP microarrays, while mouse DNA was analysed with Nimblegen array CGH. We studied 56 aphidicolin-type CFSs and 1914 regions of control, nonfragile DNA. Our theoretical in silico analysis spanned 2.16 billion nonoverlapping bases on human chromosomes 1-22. Our results provide direct experimental evidence indicating that genomic alterations were more common within CFSs in epidermal and urothelial preneoplastic lesions as well as in cancer. CFSs were on average less flexible than nonfragile regions, contained more guanine-cytosine (GC) and Alu sequences. Importantly, regions with loss-of-heterozygosity were also less flexible and had a higher Alu percentage.

Gene amplification is a relatively frequent event leading to ZBTB7A (Pokemon) overexpression in non-small cell lung cancer.

ZBTB7A (Pokemon) is a member of the POK family of transcriptional repressors. Its main function is the suppression of the p14ARF tumour suppressor gene. Although ZBTB7A expression has been found to be increased in various types of lymphoma, there are no reports dealing with its expression in solid tumours. Given that p14(ARF) inhibits MDM2, the main negative regulator of p53, we hypothesized that overexpression of ZBTB7A could lead indirectly to p53 inactivation. To this end, we examined the status of ZBTB7A and its relationship with tumour kinetics (proliferation and apoptosis) and nodal members of the p53 network in a panel of 83 non-small cell lung carcinomas (NSCLCs). We observed, in the majority of the samples, prominent expression of ZBTB7A in the cancerous areas compared to negligible presence in the adjacent normal tissue elements. Gene amplification (two- to five-fold) was found in 27.7% of the cases, denoting its significance as a mechanism driving ZBTB7A overproduction in NSCLCs. In the remaining non-amplified group of carcinomas, analysis of the mRNA and protein expression patterns suggested that deregulation at the transcriptional and post-translational level accounts for ZBTB7A overexpression. Proliferation was associated with ZBTB7A expression (p = 0.033) but not apoptosis. The association with proliferation was reflected in the positive correlation between ZBTB7A expression and tumour size (p = 0.018). The overexpression of ZBTB7A in both p53 mutant and p53 wild-type cases, implies either a synergistic effect or that ZBTB7A exerts its oncogenic properties independently of the p14(ARF)-MDM2-p53 axis. The concomitant expression of ZBTB7A with p14(ARF) (p = 0.039), instead of the anticipated inverse relation, supports the latter notion. In conclusion, regardless of the pathway followed, the distinct expression of ZBTB7A in cancerous areas and the association with proliferation and tumour size pinpoints a role for this novel cell cycle regulator in the pathogenesis of lung cancer.

Evaluation of claspin as a proliferation marker in human cancer and normal tissues.

Claspin is a nuclear protein involved in DNA replication and the DNA damage response. Its structural and functional properties suggest that it may represent a potentially useful proliferation marker. To this end, a monoclonal antibody was generated and the expression of claspin was investigated in normal fibroblasts and various cancer cell lines, as well as in tumour and normal tissues from patients with primary epithelial carcinomas. Immunoblotting analysis confirmed the specificity of the antibody, while immunohistochemistry demonstrated its applicability in archival material. In normal cells and tissues, claspin expression was weak, whereas increased levels were observed in cancer cell lines and tumour specimens. Claspin staining correlated strongly with Ki67 staining in both normal (p < 0.001) and tumour tissues (p < 0.001). However, the labelling index (LI) of claspin was consistently lower than that of Ki67, suggesting that claspin expression may be limited to a narrower part of the cell cycle. Co-localization assays with cyclin A and cell synchronization experiments indicated that claspin expression coincides with the S phase. Interestingly, the relative increase of the claspin LI in tumour samples compared with normal tissues was significantly higher (14-fold) than that of the Ki67 LI (five-fold), suggesting that claspin may be a more sensitive marker of aberrant proliferation.

Centrosome abnormalities are frequently observed in non-small-cell lung cancer and are associated with aneuploidy and cyclin E overexpression.

Centrosome abnormalities are observed in human cancers and have been associated with aneuploidy, a driving force in tumour progression. However, the exact pathways that tend to cause centrosome abnormalities have not been fully elucidated in human tumours. Using a series of 68 non-small-cell lung carcinomas and an array of in vitro experiments, the relationship between centrosome abnormalities, aneuploidy, and the status of key G1 to S-phase transition cell-cycle molecules, involved in the regulation of centrosome duplication, was investigated. Centrosome amplification and structural abnormalities were common (53%), were strongly related to aneuploidy, and, surprisingly, were even seen in adjacent hyperplastic regions, suggesting the possibility that these are early lesions in lung carcinogenesis. Cyclin E and E2F1 overexpression, but not p53 mutation, was observed to correlate with centrosome abnormalities in vivo (p = 0.029 and p = 0.015, respectively). This was further strengthened by the observation that cyclin E was specifically present in the nucleus and/or cytoplasm of the cells that contained centrosome aberrations. The cytoplasmic cyclin E signal may be attributed, in part, to the presence of truncated low-molecular-weight isoforms of cyclin E. In order to isolate the effect of cyclin E on the appearance of centrosome abnormalities, a U2OS tetracycline-repressible cyclin E cell line that has a normal centrosome profile by default was used. With this system, it was confirmed in vitro that persistent cyclin E overexpression is sufficient to cause the appearance of centrosome abnormalities.

Electron microscopy evidence that cytoplasmic localization of the p16(INK4A) "nuclear" cyclin-dependent kinase inhibitor (CKI) in tumor cells is specific and not an artifact. A study in non-small cell lung carcinomas.

It is well established that p16(INK4A) protein acts as a cell cycle inhibitor in the nucleus. Therefore, cytoplasmic localization of p16 (INK4A) usually is disregarded by investigators as nonspecific. Three recent studies reported findings that differ from the current view concerning p16(INK4A) immunohistochemical localization. All three demonstrated that breast and colon cancers expressing cytoplasmic p16(INK4) represent distinct biological subsets. We previously detected in a percentage of non-small cell lung carcinomas simultaneous nuclear and cytoplasmic p16(INK4A) staining. In view of the reports concerning breast and colon carcinomas, we conducted an ultrastructural re-evaluation of our cases to clarify the specificity of p16(INK4A) cytoplasmic expression. We observed p16 (INK4A) immunolocalization in both the nucleus and the cytoplasm of a proportion of tumor cells. Diffuse dense nuclear staining was detected in the nucleoplasm, whereas weaker granular immunoreactivity was observed in the cytoplasm near the rough endoplasmic reticulum. Negative tumor cells also were visible. In the tumor-associated stromal, cells p16(INK4A) immunoreactivity was detected only in the nuclei. We have demonstrated that p16(INK4A) cytoplasmic staining is specific and suggest that it represents a mechanism of p16(INK4A) inactivation similar to that observed in other tumor suppressor genes.

Interferon-a2b reduces neo-microvascular density in the 'normal' urothelium adjacent to the tumor after transurethral resection of superficial bladder carcinoma.

BACKGROUND: As angiogenesis represents one of the hallmarks of cancer we investigated whether intravesically administered interferon-a (IFN-a2b) reduces neo-angiogenesis in the 'normal' urothelium adjacent to the tumor in patients with superficial bladder carcinoma after complete transurethral resection (TUR) of the tumor. PATIENTS AND METHODS: In the present study 47 patients after TUR of the tumor were examined. 10 patients (group A) received no further treatment (control group); 37 patients (group B) received intravesical treatment with IFN-a2b. The instillations started within 7 days after TUR, were performed weekly for 2 months, twice a month for the next 4 months, and thereafter monthly for 6 more months. Cold cup biopsies were taken before TUR of the transitional cell carcinoma (TCC): from the tumor (T), near tumor (NT) and from normal epithelium (N). Cold cup biopsies 'near tumor', were also taken during follow-up cystoscopy (C1, C2, and C3) 2, 6, and 12 months after TUR, respectively. Angiogenesis was estimated by counting the microvessels detected with CD31 immunostaining. RESULTS: Significant differences of microvascular density (MVD) between patients of group A and B appear after TUR (p < 0.005, Kruskal-Wallis and Wilcoxon test). The MVD difference was maximal 6 months after TUR (C2(A)-C2(B), second cystoscopy) and measured at 12.17 microvessels/ mm(2) (26.2%). CONCLUSION: Our results show that the intravesical administration of IFN-a2b after TUR significantly decreases the angiogenic potential of the 'healthy' urothelium adjacent to the tumor in patients with TCC. This observation could possibly explain, to a certain extent, the mechanism by which IFN-a2b reduces the recurrence rate of primary TCC.

Immunohistochemical localization of c-mos at the light and electron microscope level in non-small cell lung carcinomas.

C-mos is a cytoplasmic upstream activator of the mitogen-activating protein kinase pathway with serine-threonine kinase activity. It plays a well established and vital role in oocyte maturation by participating in metaphase II arrest and meiotic asymmetric division, but little is known about its function in somatic cells. Recently, we observed overexpressed c-mos in a portion of non-small cell lung carcinomas (NSCLCS). In particular, c-mos immunoreactivity was detected in tumor cell nuclei in addition to its expected cytoplasmic localization, and c-mos overexpression was associated with chromosomal instability among other findings. To verify our earlier observations and to clarify further the role of c-mos in NSCLCS, we examined its distribution by both light and electron microscopy. We detected c-mos in the cytoplasm and/or nucleus of a portion of tumor cells and fibroblasts. In particular, granular immunoreactivity was observed in the cytoplasm closely associated with the rough endoplasmic reticulum. Nuclear staining was confirmed and was often found near the nuclear membrane, as well as in some large multilobular, possibly aneuploid, nuclei. C-mos positivity was also found in the nuclei of tumor cells undergoing apoptosis. Furthermore, c-mos was detected in areas with diminished vascularization. It should be noted that nuclear staining was found at the ultrastructural level more extensively than at the light microscope study. This suggests a masking effect by the hematoxylin nuclear counterstain.

Relationship of the K-ras/c-mos expression patterns with angiogenesis in non-small cell lung carcinomas.

BACKGROUND: Neo-angiogenesis is an acquired capability vital for a tumor to grow and metastasize. Evidence has shown that the mitogen-activated protein (MAP) kinase pathway is involved in this process. Alterations of K-ras and c-mos, two pivotal components of this pathway, have been implicated in non-small cell lung carcinogenesis. In the present report, we examine, in a series of non-small cell lung carcinomas (NSCLCs), the status of K-ras and c-mos oncoproteins in correlation with the tumor neo-angiogenesis state and the major angiogenic factor, vascular endothelial growth factor (VEGF). MATERIALS AND METHODS: c-mos and p-ERK1/2 status was evaluated immunohistochemically in a total of 65 NSCLCs, whereas the presence of K-ras mutations was examined by reverse transcriptase-polymerase chain reaction (RT-PCR) restriction fragment length polymorphism (RFLP) in available matched normal tumor material from 56 cases. Microvessel density (MVD) was estimated by immunodetection of CD3, endothelial marker, and VEGF expression was assessed by immunohistochemistry. All possible associations were examined by a series of statistical methods. RESULTS: Expression of oncogenic activated K-ras and c-mos overexpression was observed in 12 of 49 (25%) and in 16 of 61 (26%) informative cases, respectively. Only 1 of the 25 deregulated for K-ras or c-mos cases exhibited both alterations, suggesting a mutually exclusive relationship between activated K-ras and c-mos overexpression (p = 0.074) in a subset of NSCLCs. In these cases, the MAPK kinase kinase/MEK/ERK pathway was found to be activated. MVD and VEGF expression were 36.9 +/- 10.6 mv/mm2 and 73.1 +/- 20.0%, respectively. The most intriguing finding was that the [K-ras(No)/c-mos(P)] profile was significantly associated with low MVD levels compared to normal cases (p = 0.004); by contrast, no correlation was found between the other K-ras/c-mos patterns and MVD. Furthermore, the former group exhibited the lowest VEGF levels. CONCLUSIONS: The mutually exclusive relationship between mutated K-ras and c-mos overexpression in a subset of NSCLCs implies a common signal transduction pathway in lung carcinogenesis. The effect of this pathway on NSCLC neo-angiogenesis seems to depend upon the status of c-mos, which acts as a molecular "switch," possibly exerting a negative selective pressure on tumor progression.

Sensitive differential detection of genetically related mycobacterial pathogens in archival material.

A polymerase chain reaction (PCR) assay targeted to the immunogenic protein MPB64 gene was used to detect members of the Mycobacterium tuberculosis complex, and an outward-primed PCR (OPPCR) designed on the IS6110 element allowed differentiation between Mycobacterium bovis and Mycobacterium tuberculosis. Additionally, the amplification of IS1110 and 16S ribosomal RNA sequences combined with a dot blotting assay were able to differentially detect Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium paratuberculosis. The validity of the experimental procedure was tested on reference material and formalin-fixed paraffin-embedded samples from patients with tuberculosis, sarcoidosis, or Crohn disease. We demonstrated mycobacterial DNA in 59 of 75 cases with histologic lesions typical of tuberculosis; we detected M tuberculosis and M paratuberculosis in 6 of 25 sarcoidosis cases and in 7 of 20 Crohn disease specimens, respectively. The proposed diagnostic procedure is directly applicable to archival material and allows differentiation of genetically related mycobacterial pathogens in more detail than other molecular methods. It provides a tool for the diagnostic study of tuberculosis, sarcoidosis, and Crohn disease.