Clinical implications of the p53 gene

HPV infection and its correlation with p53 and Bcl-2 among pregnant mothers and their infants

The investigation of perinatal transmission of HPV is vital for early screening of cervical/oral cancers. Here, transmission of HPV from the pregnant women to their infants was studied. p53 and Bcl-2 expressions and their correlations with HPV infection were examined. HPV infection was detected in the cervical and oral swabs of 135 mother-baby pairs employing both PCR and HC-II methods. 1 year follow-up with an interim visit at 3 months for mothers and 6 months for babies was performed. Immunocytochemistry of p53 and Bcl-2 using the streptavidin-biotin peroxidase method was performed. Prevalence of HPV infection in the mothers was 28.14%, (38/135) and 30.37% (41/135) determined by the PCR and HC-II methods respectively. HPV 16 and/or 18 was identified in 81.57% (31/38) and 82.92% (34/41) of the HPV + women estimated by PCR and HC-II methods respectively. Prevalence rate of HPV 16 among the HPV + pregnant women was 63.15% (24/38) and 65.85% (27/41) determined by PCR and HC-II methods respectively. The frequency of perinatal transmission was 21.05% (8/38) and 21.95% (9/41) determined by PCR and HC-II methods respectively at birth. The HPV + infants in the follow up study cleared the infection within 6 weeks. An abnormal nuclear expression of p53 and cytoplasmic expression of Bcl-2 were observed in the HPV + mother-baby pairs. Cesarean section did not protect the infants against perinatal HPV transmission. The detection of p53 and Bcl-2 proteins in the HPV + mother-baby pairs suggests that these biomarkers may be important in the early screening of oral/cervix cancers in positive cases.

Cannabidiol-induced crosstalk of apoptosis and macroautophagy in colorectal cancer cells involves p53 and Hsp70

Although it has been established that cannabidiol (CBD), the major non-psychoactive constituent of cannabis, exerts antitumoral activities, the exact mechanism(s) via which tumor cells are killed by CBD are not well understood. This study provides new insights into the potential mechanisms of CBD-induced mutual antagonism of apoptosis and macroautophagy using wild type (HCT116 p53wt, LS174T p53wt), knockout (HCT116 p53-/-) and mutant (SW480 p53mut) human colorectal cancer cells (CRC). CBD causes a more pronounced loss in the viability of p53wt cells than p53-/- and p53mut cells, and a 5-week treatment with CBD reduced the volume of HCT116 p53wt xenografts in mice, but had no effect on the volume of HCT116 p53-/- tumors. Mechanistically, we demonstrate that CBD only significantly elevates ROS production in cells harboring wild-type p53 (HCT116, LS174T) and that this is associated with an accumulation of PARP1. CBD-induced elevated ROS levels trigger G0/G1 cell cycle arrest, a reduction in CDK2, a p53-dependent caspase-8/9/3 activation and macroautophagy in p53wt cells. The ROS-induced macroautophagy which promotes the activation of keap1/Nrf2 pathway might be positively regulated by p53wt, since inhibition of p53 by pifithrin-α further attenuates autophagy after CBD treatment. Interestingly, an inhibition of heat shock protein 70 (Hsp70) expression significantly enhances caspase-3 mediated programmed cell death in p53wt cells, whereas autophagy-which is associated with a nuclear translocation of Nrf2-was blocked. Taken together, our results demonstrate an intricate interplay between apoptosis and macroautophagy in CBD-treated colorectal cancer cells, which is regulated by the complex interactions of p53wt and Hsp70.

Human papillomavirus maybe is a critical player in the regulation of chemoresistance related factors (P53, Rb, TWIST, Bcl-2, Bcl-XL, c-IAP2, cytochrome C, and caspase 3) in breast cancer

As one of the frequent malignancies, breast cancer (BCa) is the foremost reason for cancer-related deaths among women. The role of Human papillomavirus (HPV) in chemoresistance has rarely been investigated in previous studies. The current study sets out to the possible role of HPV in BCa chemoresistance. In this research, 90 BCa tissue and 33 normal breast tissue were collected. We evaluated the presence of the HPV genome along with the viral (E2, E6, E7) and cellular gene expression associated with cell resistance to death. Statically significant differences in the prevalence of HPV between the BCa group (25.2% or 23/90) and the control group (21.8% or 7/32) were not found. HPV-16 and HPV-18 genotypes were the abundant HPV genotypes. Resistance to the Adriamycin-Cyclophosphamide (AC), paclitaxel regimen was elevated in the HPV- group (56/70) in comparison to the HPV+ group (14/70). Nevertheless, there was no significant difference in the prevalence of resistance to AC + paclitaxel + triple-negative breast cancer combination therapy between the HPV+ group (9/20) and in the HPV- group (11/20). In the BCa group in contrast to the control group, the expression level of Bcl-2, BCL-XL, and c-IAP2 demonstrated a significant decrease, while, the expression level of cytochrome C and caspase 3 was significantly increased. This study suggests that HPV infection might contribute to BCa chemoresistance through disrupt cellular genes involved in cell death.

Interrelated Oncogenic Viruses and Breast Cancer

Breast Cancer is a multifactorial disease and recent evidence that viruses have a greater role in its aetiology and pathophysiology than previously hypothesized, has garnered a lot of attention in the past couple of years. After the role of Mouse Mammary Tumour Virus (MMTV) in the oncogenesis of breast cancer has been proved in mice, search for similar viruses found quite a plausible relation of Human Papilloma Virus (HPV), Epstein–Barr virus (EBV), and Bovine Leukaemia Virus (BLV) with breast cancer. However, despite practical efforts to provide some clarity in this issue, the evidence that viruses cause breast cancer still remains inconclusive. Therefore, this article aims to clarify some ambiguity and elucidate the correlation of breast cancer and those particular viruses which are found to bring about the development of tumorigenesis by a previous infection or by their own oncogenic ability to manipulate the molecular mechanisms and bypass the immune system of the human body. Although many studies have reported, both, the individual and co-existing presence of HPV, EBV, MMTV, and BLV in patient sample tissues, particularly in Western women, and proposed oncogenic mechanisms, majority of the collective survey of literature fails to provide a delineated and strong conclusive evidence that viruses do, in fact, cause breast cancer. Measures to prevent these viral infections may curb breast cancer cases, especially in the West. More studies are needed to provide a definite conclusion.

Possible role of HPV/EBV coinfection in anoikis resistance and development in prostate cancer

BACKGROUND

This study aimed to evaluate the possible role of human papillomavirus (HPV) and Epstein-Barr virus (EBV) coinfection as an etiological factor for prostate cancer (PCa) development.

METHODS

This case-control study was conducted on 67 patients with PCa and 40 control subjects. The expression levels of cellular and viral factors involved in inflammation, tumor progression, and metastasis were quantified, using the enzyme-linked immunosorbent assay (ELISA) and quantitative real-time polymerase chain reaction (qRT-PCR) assay.

RESULTS

The EBV/HPV coinfection was reported in 14.9% of patients in the case group and 7.5% of the control subjects. The high-risk types of HPV, that is, HPV 16 and HPV 18, were responsible for 50 and 30% of HPV/EBV-coinfected PCa cases (n = 10), respectively. No significant relationship was observed between PCa and HPV/EBV coinfection (OR = 2.9, 95% CI: 0.18-45.2, P = 0.31). However, the highest percentage of HPV genome integration was found in the HPV/EBV-coinfected PCa group (8/10; 80%). Also, the mean expression levels of inflammatory factors (IL-17, IL-6, TNF-α, NF-κB, VEGF, ROS, and RNS), anti-apoptotic mediators (Bcl-2 and survivin), and anti-anoikis factors (Twist and N-cadherin) were significantly higher in the HPV/EBV-coinfected PCa group, compared to the non-coinfected PCa cases. Nevertheless, the tumor-suppressor proteins (p53 and pRb) and E-cadherin (inhibitor of anoikis resistance) showed significant downregulations in the HPV/EBV-coinfected PCa group, compared to the non-coinfected PCa cases.

CONCLUSION

The HPV/EBV coinfection may be an etiological factor for PCa through modulation of cellular behaviors.

The assessment of a possible link between HPV-mediated inflammation, apoptosis, and angiogenesis in Prostate cancer

BACKGROUND

The aim of this study was to determine the presence of HPV in patients with Prostate cancer (PCa) and its possible association with cancer progression.

METHODS

In this case-control study, fresh prostate tissues and blood samples were collected from 90 individuals, including 58 cases samples with PCa and 32 non-malignant prostate tissue samples as a control group. The expression level of viral genes (E2, E6, and E7) and cellular factors including tumor suppressor proteins (Rb and p53), anti-apoptotic mediators (Bcl-2 and survivin), and some mediators involved in inflammation and angiogenesis was evaluated.

RESULTS

The presence of the HPV genome was identified in 19 out of the 58 cases (32.7%) and five out of the 32 controls (15.6%). However, there was not any statistically significant relationship between the presence of the HPV genome and PCa (OR = 2.63, 95% C.I = 0.89-7.91, P-value = 0.078). Moreover, the HPV high-risk genotypes 16 and 18 were detected in 47.4% and 31.6% of HPV-infected PCa tissues, respectively. The expression level of the tumor suppressor proteins (Rb and p53) significantly decreased in the HPV-infected samples compared to the HPV negative specimens (P-value = 0.01, P-value = 0.01, respectively). However, the expression level of the anti-apoptotic mediators and those involved in angiogenesis and inflammation significantly increased in the HPV-infected PCa group compared to the HPV-negative PCa and control groups (P-value < 0.05, respectively).

CONCLUSION

Our study suggests that although it is not definitely known whether HPV causes PCa, this virus probably modulates PCa cell behavior by affecting inflammation, angiogenesis, and apoptosis mechanisms, which, in turn, promotes tumorigenesis.

Evaluating the scope of intramedullary invasion of malignant bone tumor by DCE-MRI quantitative parameters in animal study

The purpose was to analyze the value of quantitative parameters of DCE-MRI in evaluating micro-infiltration of malignant bone tumors.

METHODS

Thirty-nine New Zealand white rabbits were used to establish malignant bone tumor models by implanting VX2 tumor fragments into the right tibiae. After three weeks, models were examined by conventional MRI and DCE-MRI; then the right tibiae were cut into sagittal sections and partitioned into histology slices for comparison with microscopic findings. Micro-infiltration groups were selected and the range of infiltration was determined under the microscope, and corresponding DCE images analyzed to obtain the quantitative parameters include Ktrans, Kep, v_e and v_p in parenchyma areas, micro-infiltration areas and simple edema areas. One-way ANOVA was used to compare the differences of the parameters between the three areas. Receiver operating characteristic curves (ROCs) were plotted to determine the accuracy of different parameters by area under curves (AUCs).

RESULTS

22 cases (22/39, 56.4%) were included in the micro-infiltration group and the infiltration depth ranged from 1.3 mm to 4.6 mm, with an average depth of 3.2 mm ± 0.8 mm. The statistical results of quantitative parameters in the three areas were as follows: Ktrans values were (0.494 ± 0.052), (0.403  ±  0.049), (0.173 ± 0.047) min^-1 (p = =0.000), Kep values were (1.959 ± 0.65), (1.528 ± 0.372), (1.174 ± 0.486) min^-1 (p = =0.000), v_e values were (0.247 ± 0.068), (0.283 ± 0.057), (0.168 ± 0.062) min^-1 (p = =0.000), v_p values were (0.125 ± 0.036), (0.108 ± 0.033), (0.098 ± 0.025) min^-1 (p = =0.022), respectively. Ktrans and Kep values had significant difference in the three areas after comparing between-groups, respectively. However, there were no significant difference in v_p values between parenchyma and micro-infiltration areas (p = =0.078), micro-infiltration and simple edema areas (p = =0.315), and v_e values between parenchyma and micro-infiltration areas (p = =0.056). The v_e values were higher in parenchyma and micro-infiltration areas then simple edema areas. Ktrans had highest accuracy in differentiating different areas (AUC > 0.9), respectively.

CONCLUSION

Quantitative parameters Ktrans, Kep and v_e can assess the extent of intramedullary invasion of malignant bone tumors. Ktrans have highest accuracy in differentiating different regions.

Expression patterns and mutation analysis of p53 in fish Rita rita from polluted riverine environment

The present study was undertaken to investigate the alterations in gene expression patterns and for mutation analysis of p53 in the riverine catfish Rita rita collected from polluted riverine habitat. The partial p53 gene sequence of Rita rita generated showed a high degree of similarities with the DNA binding domains of fishes, mice and human. Transcriptomic analysis, carried out by quantitative real-time Polymerase Chain Reaction (RT-qPCR), showed significant down-regulation of p53 in fishes collected from most of the polluted stretches. Similar trend in protein abundance was observed by western blot analysis. Down-regulation of p53 was more pronounced in gill than liver. Expression patterns of p53 suggest that exposure to a multitude of contaminants in the natural riverine ecosystem could suppress the expression of p53. Genomic DNA showed a low stained smear pattern upon electrophoresis, with no evidence of DNA fragmentation. For mutation analysis PCR-SSCP followed by sequence analysis was carried out, which identified eight mutations; two at codon level and six missense mutations in the DNA binding domain IV and V. Secondary structure prediction showed that these mutations could lead to impairment of protein structure. Thus, the present study indicated that aquatic pollution has impacted these lower vertebrates which are reflected by the down-regulation of tumor suppressor protein (p53) in majority of the stretches studied.

HPV Status and Its Correlation with BCL2, p21, p53, Rb, and Survivin Expression in Breast Cancer in a Chinese Population

Despite recent evidence, the role of human papillomavirus (HPV) in breast carcinogenesis is controversial. The correlations of HPV infection with the clinicopathological features of breast cancer and the expression of cell cycle/apoptosis-associated proteins have not been well elucidated. In this study, we sought to determine the prevalence of high-risk HPVs (HR-HPVs) infection and BCL2, p21, p53, Rb, and survivin expression in breast cancer patients and to investigate the relationship of HPV with these cancer-related proteins, in an attempt to clarify the potential mechanism of HPV in breast cancer pathogenesis. HPV presence in 81 fresh breast cancer tissues was determined by hybrid capture 2 (HC2) assay, and expression of BCL2, p21, p53, Rb, and survivin was detected by immunohistochemistry. Here we showed that fourteen (17.3%) patients were HR-HPV positive. HPV infection demonstrated no significant correlation with the clinicopathological characteristics of breast cancer. HPV-positive tumors showed significantly higher BCL2 and lower p53 expression than HPV-negative tumors. Expression of p21, Rb, and survivin was not associated with HPV status. Our results suggest a possible role of HR-HPV in breast cancer carcinogenesis, in which BCL2 and p53 may be involved.

Immunohistochemical Expression of Human Epidermal Growth Factor Receptor 2 (HER2) and p53 in Gastric Adenocarcinoma: A Pilot Study from Northern India

INTRODUCTION

After the recent approval of Trastuzumab (anti-HER2 antibody) for the treatment of HER2 overexpressed Gastric Adenocarcinoma (GA), importance of HER2 testing is increasingly recognized. However, there is paucity of studies for HER2 overexpression in the Indian patients of GA. Similarly, study of p53 expression in the Indian patients of GA is infrequent.

AIM

To study immunohistochemical expression of HER2 and p53 in GA biopsy samples.

MATERIALS AND METHODS

This was a cross-sectional observational study. The expression of HER2 and p53 by immunohistochemistry were analyzed in 50 cases of GA. The HER2 expression was scored as negative (0 and 1+), equivocal (2+), and overexpression (3+). The p53 expression was quantified as negative (0-9% tumour cells) and positive (≥10% tumour cells). The intensity of p53 expression was assessed as strong and weak.

RESULTS

Mean age of the patients was 56.8±14.8 years. Male:female ratio was 2:1. Histological types of adenocarcinoma were intestinal (68%), diffuse (28%), and indeterminate (4%). HER2 overexpression and equivocal results were present in 10% cases, each. Overall, a positive expression of p53 was seen in 72% (strong and weak intensities: 66.7% and 33.3% cases, respectively).

CONCLUSION

As compared to HER2 overexpression, a higher incidence of p53 expression was seen (10% vs.72%) in GA.

TP53 Y220C Is a Hotspot Mutation in Oropharyngeal Squamous Cell Carcinoma

OBJECTIVES

Although TP53 mutations in head and neck squamous cell carcinoma (HNSCC) have been extensively studied, their association with the different subsites in the head and neck region has never been described.

METHODS

Sanger sequence analysis evaluating exons 4-9 in the TP53 gene was performed on 116 HNSCC patients. The exon location, exact codon and corresponding substitution in relation to the anatomical site (subsite) of the HNSCC were evaluated.

RESULTS

We found nonsynonymous TP53 mutations in 70% (81/116) of the patients. In oral cavity carcinomas, most mutations occurred in exon 7 (37%). In oropharyngeal and laryngeal tumors, mutations were mainly found in exons 6 and 7. The most common mutation was located in codon 220, and all of these were an Y220C mutation. Five out of nine (56%) Y220C mutations occurred in oropharyngeal tumors. Additionally, 22% of all mutations observed in oropharyngeal squamous cell carcinoma (OPSCC) consisted of Y220C mutations.

CONCLUSION

In this study, the subsite-related distribution of TP53 mutations underlines the biological diversity between tumors arising from different anatomical regions in the head and neck region. Moreover, the Y220C mutation was by far the most prevalent TP53 mutation in HNSCC and a relative hotspot mutation in the oropharynx. © 2015 S. Karger AG, Basel.

Distinct Rayleigh scattering from hot spot mutant p53 proteins reveals cancer cells

The scattering of light redirects and resonances when an electromagnetic wave interacts with electrons orbits in the hot spot core protein and oscillated electron of the gold nanoparticles (AuNP). This report demonstrates convincingly that resonant Rayleigh scattering generated from hot spot mutant p53 proteins is correspondence to cancer cells. Hot spot mutants have unique local electron density changes that affect specificity of DNA binding affinity compared with wild types. Rayleigh scattering changes introduced by hot-spot mutations were monitored by localized surface plasmon resonance (LSPR) shift changes. The LSPR λmax shift for hot-spot mutants ranged from 1.7 to 4.2 nm for mouse samples and from 0.64 nm to 2.66 nm for human samples, compared to 9.6 nm and 15 nm for wild type and mouse and human proteins, respectively with a detection sensitivity of p53 concentration at 17.9 nM. It is interesting that hot-spot mutants, which affect only interaction with DNA, launches affinitive changes as considerable as wild types. These changes propose that hot-spot mutants p53 proteins can be easily detected by local electron density alterations that disturbs the specificity of DNA binding of p53 core domain on the surface of the DNA probed-nanoplasmonic sensor.

Molecular Diagnostic Applications in Colorectal Cancer

Colorectal cancer, a clinically diverse disease, is a leading cause of cancer-related death worldwide. Application of novel molecular diagnostic tests, which are summarized in this article, may lead to an improved survival of colorectal cancer patients.  Distinction of these applications is based on the different molecular principles found in colorectal cancer (CRC). Strategies for molecular analysis of single genes (as KRAS or TP53) as well as microarray based techniques are discussed. Moreover, in addition to the fecal occult blood testing (FOBT) and colonoscopy some novel assays offer approaches for early detection of colorectal cancer like the multitarget stool DNA test or the blood-based Septin 9 DNA methylation test. Liquid biopsy analysis may also exhibit great diagnostic potential in CRC for monitoring developing resistance to treatment. These new diagnostic tools and the definition of molecular biomarkers in CRC will improve early detection and targeted therapy of colorectal cancer.

Liposomal formulations of Etoposide and Docetaxel for p53 mediated enhanced cytotoxicity in lung cancer cell lines

The objective of present investigation was to develop and assess comparative enhancement in cytotoxicity of liposomal Etoposide and Docetaxel in non-small cell lung cancer cell lines after pre-treatment and co-administration of p53 tumor suppressor gene and to assess direct lung targeting of optimized formulations by dry powder inhaler technology. Cationic liposomes with and without drug were prepared and allowed to form p53-lipoplex for undertaking cytotoxicity studies in H-1299 (p53 null) and A-549 (p53 wt) cell lines. The optimized lipoplexes showed average size of 200-350 nm, zeta potential of 25-32 mV and sustained drug release up to 16-24 h. The developed liposomes and lipoplexes showed significant intracellular uptake and demonstrated enhanced cytotoxicity of 13-28 % after p53-drug co-administration and 41-63 % after p53 pre-treatment. The p53 mediated enhanced cytotoxicity by increased apoptosis and necrosis was also confirmed using Annexin V - FITC assay. The increased apoptosis suggested restored p53 function and reduced anti-apoptotic drug resistance theirby causing cell sensitization and synergism towards cytotoxicity. The studies conducted above demonstrated significant cell chemo-sensitization after p53 pre-treatment followed by Etoposide/Docetaxel liposomes administration than p53-Etoposide or p53-Docetaxel lipoplex co-administration; more significantly in Docetaxel and in H 1299 cell line. All the formulations when developed as dry powder inhalers showed significant in vitro lung deposition pattern in cascade impactor with fine particle faction of 33-37%. The study opens up a new strategy to treat lung cancer especially in cases of drug resistance. Moreover direct delivery to lung may provide an important role in complete remission of the disease due to target specificity.

Present and future directions of translational research on aflatoxin and hepatocellular carcinoma. A review

The aflatoxins were discovered in toxic peanut meal causing "turkey X" disease, which killed large numbers of turkey poults, ducklings and chicks in the UK in the early 1960s. Extracts of toxic feed induced the symptoms in experimental animals, and purified metabolites with properties identical to aflatoxins B(1) and G(1) (AFB(1) and AFG(1)) were isolated from Aspergillus flavus cultures. Structure elucidation of aflatoxin B(1) was accomplished and confirmed by total synthesis in 1963. AFB(1) is a potent liver carcinogen in rodents, non-human primates, fish and birds, operating through a genotoxic mechanism involving metabolic activation to an epoxide, formation of DNA adducts and, in humans, modification of the p53 gene. Aflatoxins are unique among environmental carcinogens, in that elucidation of their mechanisms of action combined with molecular epidemiology provides a foundation for quantitative risk assessment; extensive evidence confirms that contamination of the food supply by AFB(1) puts an exposed population at increased risk of developing hepatocellular carcinoma (HCC). Molecular biomarkers to quantify aflatoxin exposure in individuals were essential to link aflatoxin exposure with liver cancer risk. Biomarkers were validated in populations with high HCC incidence in China and The Gambia, West Africa; urinary AFB(1)-N (7)-Guanine excretion was linearly related to aflatoxin intake, and levels of aflatoxin-serum albumin adducts also reflected aflatoxin intake. Two major cohort studies employing aflatoxin biomarkers identified their causative role in HCC etiology. Results of a study in Shanghai men strongly support a causal relationship between HCC risk and the presence of biomarkers for aflatoxin and HBV infection, and also show that the two risk factors act synergistically. Subsequent cohort studies in Taiwan confirm these results. IARC classified aflatoxin as a Group 1 human carcinogen in 1993, based on sufficient evidence in humans and experimental animals indicating the carcinogenicity of naturally occurring mixtures of aflatoxins, aflatoxin B(1), G(1) and M(1). Aflatoxin biomarkers have also been used to show that primary prevention to reduce aflatoxin exposure can be achieved by low-technology approaches at the subsistence farm level in sub-Saharan Africa. Also, in residents of Qidong, China, oral dosing with chlorophyllin, a chlorophyll derivative, prior to each meal led to significant reduction in aflatoxin-DNA biomarker excretion, supporting the feasibility of preventive measures to reduce HCC risk in populations experiencing unavoidable aflatoxin exposure. The systematic, comprehensive approach used to create the total aflatoxin database justifies optimism for potential success of preventive interventions to ameliorate cancer risk attributable to aflatoxin exposure. This strategy could serve as a template for the development, validation and application of molecular and biochemical markers for other carcinogens and cancers as well as other chronic diseases resulting from environmental exposures.

Investigation of Differences in P53 Gene Polymorphisms between Schizophrenia and Lung Cancer Patients in the Turkish Population

Objective. The reduced incidence of cancer observed in schizophrenia patients may be related to differences in genetic background. It has been suggested that genetic predisposition towards schizophrenia is associated with reduced vulnerability to lung cancer, and p53 gene is one of the candidate genes. In our study, we aimed to investigate polymorphisms in the BstUI in exon 4 and MspI in intron 6 restriction sites of the p53 gene in Turkish schizophrenia patients, lung cancer patients, and controls. Material and Methods. Allele and genotype incidence of these polymorphisms with their haplotype combinations were studied in 100 Turkish lung cancer and schizophrenia patients and 100 controls without malignant and schizophrenia diseases. The genotype characteristics were determined by PCR-based RFLP method using DNA extracted from peripheral blood. Results. For the BstUI and MspI polymorphism, there were found significant differences in the genotype and allele frequencies between schizophrenia and lung cancer patients with control groups (P < .01). The analysis based on haplotype frequencies showed the presence of BstUI-MspI 2-1 haplotype in cancer patients (12%) in contrast to the absence of this haplotype in schizophrenia and controls. Only in lung cancer patients we found both significant decrease of A1 allele of the p53 codon 72 (OR 0.23, 95% CI 0.9–0.58) and A1/A1 homozygous genotype (P < .0001, OR 0.19). Conclusion. The results of this study suggest a protective effect of A1 allele against lung cancer, and the p53 MspI polymorphism may modify the susceptibility to lung cancer as a single factor rather than in combination with BstUI polymorphism.

The tumor microenvironment and DNA repair

Genetic instability is one of the hallmarks of cancer cells. As tumors grow, they progressively acquire mutations that ultimately allow them to invade normal tissues and metastasize to distant sites. This increased propensity for mutation also leads to cancers that are resistant to therapeutic intervention. Recent evidence has shown that the tumor microenvironment plays a major role in the etiology of this phenomenon; as tumors are exposed to repeated cycles of hypoxia and reoxygenation, they downregulate a number of DNA repair pathways, thus leading to genetic instability. Understanding the mechanisms involved in this process may provide insights into the development of novel treatment strategies.

Metabolism and brain cancer

Cellular energy metabolism is one of the main processes affected during the transition from normal to cancer cells, and it is a crucial determinant of cell proliferation or cell death. As a support for rapid proliferation, cancer cells choose to use glycolysis even in the presence of oxygen (Warburg effect) to fuel macromolecules for the synthesis of nucleotides, fatty acids, and amino acids for the accelerated mitosis, rather than fuel the tricarboxylic acid cycle and oxidative phosphorylation. Mitochondria biogenesis is also reprogrammed in cancer cells, and the destiny of those cells is determined by the balance between energy and macromolecule supplies, and the efficiency of buffering of the cumulative radical oxygen species. In glioblastoma, the most frequent and malignant adult brain tumor, a metabolic shift toward aerobic glycolysis is observed, with regulation by well known genes as integrants of oncogenic pathways such as phosphoinositide 3-kinase/protein kinase, MYC, and hypoxia regulated gene as hypoxia induced factor 1. The expression profile of a set of genes coding for glycolysis and the tricarboxylic acid cycle in glioblastoma cases confirms this metabolic switch. An understanding of how the main metabolic pathways are modified by cancer cells and the interactions between oncogenes and tumor suppressor genes with these pathways may enlighten new strategies in cancer therapy. In the present review, the main metabolic pathways are compared in normal and cancer cells, and key regulations by the main oncogenes and tumor suppressor genes are discussed. Potential therapeutic targets of the cancer energetic metabolism are enumerated, highlighting the astrocytomas, the most common brain cancer.

Tobacco, Genetic Susceptibility and Lung cancer

Exposure to tobacco smoke is an established risk factor for lung cancer, although a possible role for genetic susceptibility in the development of lung cancer has been inferred from familial clustering of the disease and segregation analysis. Findings of familial aggregation and statistical evidence for a major susceptibility gene have led to the search for high penetrant, rare, single genes and low penetrant, high frequency susceptibility genes for lung cancer. The relatively small number of linkage studies conducted to date, have identified potential lung cancer susceptibility loci on chromosomes 6q, 12p, and 19q. A variety of studies have examined single nucleotide polymorphisms of several low penetrant, high frequency genes encoding for enzymes involved in the metabolism of carcinogens and DNA damage repair, as likely candidate susceptibility genes. These studies have produced somewhat conflicting findings and, when significant, only modest associations have been reported. Relatively few studies have looked for potential gene-environment interactions, explored associations between two or more genetic polymorphisms or evaluated interactions between genetic polymorphisms and endogenous risk factors. Few large scale genome wide association studies conducted recently have provided evidence that common variation on chromosome 15q25.1, 5p15.33 and 6p21.33 influences lung cancer risk and cancer types with strong environmental risk factors. It is hoped that newer research strategies, selecting candidate genes within pathways and genotype at multiple markers within a gene, employing new technologies, may allow complete coverage of the variation within candidate genes in multiple pathways and to unravel the genetic susceptibility to lung cancer. This knowledge could, in turn, be used to identify persons at risk, to individualize treatments such as chemoprevention, to personalize harms of smoking and to motivate cessation.

Interactions between MDM2 and TP53 Genetic Alterations, and Their Impact on Response to MDM2 Inhibitors and Other Chemotherapeutic Drugs in Cancer Cells

PURPOSE: MDM2 is a key negative regulator of the p53 signaling pathway. We aimed to evaluate the inter-relationships between MDM2 SNP309, mRNA expression, amplification, and TP53 mutations, as well as their correlations with responsiveness to MDM2 inhibitors and other commonly used cytotoxic drugs tested in the NCI-60 cancer cell panel. EXPERIMENTAL DESIGN: SNP309 was genotyped in the NCI-60 cancer cell lines. MDM2 mRNA levels and gene copy number were measured using real-time PCR. We assessed the inter-relationship between MDM2 genetic alterations, TP53 mutations, and the cytotoxicity of two MDM2 inhibitors (RITA and Nutlin-3) as well as 111 other drugs with known mechanisms of action. RESULTS: In the overall NCI-60 cell panel, MDM2 mRNA levels were not associated with SNP309 but with increased gene copy number. However, SNP309 strongly determined the MDM2 mRNA expression in cancer cells with wild-type TP53. Cancer cells with wild-type TP53 also had significantly higher MDM2 copies. In the overall panel, MDM2 copy number was independently correlated with increased sensitivity to commonly used alkylating agents and topoisomerase I and II inhibitors. SNP309 was significantly associated with increased sensitivity to alkylating agents and topoisomerase I inhibitors in the cells with wild-type TP53. In addition, TP53 mutations were the only factor significantly associated with cellular resistance to the MDM2 inhibitor RITA. CONCLUSIONS: Our results suggest that MDM2 copy number and SNP309 may predict for response to alkylating agents and topoisomerase inhibitors. These markers should be tested further, particularly in combination with other putative predictive biomarkers. (Clin Cancer Res 2009;15(24):7602-7).

Oligonucleotide probe array for p53 gene alteration analysis in DNA from formalin-fixed paraffin-embedded breast cancer tissues

Mutations in the TP53 tumor-suppressor (p53) gene represent the most common molecular changes in various malignancies, including breast cancer (BC). We sequenced the p53 gene in DNA extracted from archival paraffin-embedded BC tissues and compared the results obtained from direct sequencing with those obtained by oligonucleotide probe array (OPA). DNA was extracted from 34 samples. OPA correctly detected 13 genetic alterations in 14 cases, with a mutation frequency of 41.2%. No changes were detected in exons 3, 4, 9, 10, and 11 and no polymorphisms were found. Direct manual sequencing in which DNA was amplified by PCR showed 21 genetic mutations in 19 (55.9%) cases. Eight mutations were identified by both OPA and PCR methods. Although OPA detected fewer gene alterations than direct sequencing, the difference was not significant (P= 0.11). In conclusion, the OPA may be safely used to identify individual genetic variations of human p53 gene in BC specimens.

Isorhamnetin protects rat ventricular myocytes from ischemia and reperfusion injury

Ischemia/reperfusion (I/R) has been known to cause damages to ventricular myocytes. Isorhamnetin, one member of flavonoid compounds, has cardioprotective effect, the effect that suggests a possible treatment for I/R damages. In the present investigation, we found that isorhamnetin could significantly promote the viability of neonatal rat ventricular myocytes that were exposed to ischemia/reperfusion (I/R) in vitro. Ventricular myocytes were obtained from neonatal SD rats, and then were divided randomly into three groups, namely I/R-/isor-, I/R+/isor- and I/R+/isor+ group. Before the whole experiment, the most appropriate concentration of isorhamnetin (4 μM) was determined by MTT assay. Our results showed that isorhamnetin could alleviate the damages of I/R to ventricular myocytes through inhibiting lactate dehydrogenase (LDH) activity, and repressing apoptosis. Compared with the counterpart of the I/R+/isor- group, LDH activity in the isorhamnetin-treated group weakened, halving from 24.1 ± 2.3 to 11.4 ± 1.2U/L. Additionally, flow cytometry showed the apparently increased apoptosis rate induced by I/R, the result that was further confirmed by transmission electron microscope. Administration of isorhamnetin, however, assuaged the apoptosis induced by I/R. Corresponding to the reduced apoptosis rate in the I/R+/isor+ group, western blotting assay showed increased amount of Bcl-2 and p53, decreased amount of Bax, and nuclear accumulation of NF-κB/p65.

A meta-analysis of TP53 codon 72 polymorphism and lung cancer risk: evidence from 15,857 subjects

The genetic polymorphism of TP53 codon 72 is thought to have significant effect on lung cancer risk, but the results are inconsistent. In this meta-analysis, we assessed 23 published studies involving 15,857 subjects of the association between TP53 codon 72 polymorphism and risk of lung cancer. For the homozygote Pro/Pro and Pro allele carriers (Pro/Pro+Pro/Arg), the ORs for all studies combined (7495 cases and 8362 controls) were 1.221 (95% CI=1.046-1.425; P=0.021 for heterogeneity) and 1.148 (95% CI=1.040-1.266; P=0.008 for heterogeneity). In the stratified analysis by ethnicity, significantly increased risks were found in Asians (3254 cases and 3350 controls) for both the homozygote Pro/Pro (OR=1.395; 95% CI=1.206-1.613; P=0.806 for heterogeneity) and the Pro allele carriers (OR=1.109; 95% CI=1.000-1.228; P=0.458 for heterogeneity). In Caucasians (3359 cases and 3953 controls), significantly elevated risk was associated with Pro allele carriers (OR=1.180; 95% CI=1.029-1.353; P=0.073 for heterogeneity). In the subgroup analyses by pathological type, the ORs for the homozygote Pro/Pro and Pro allele carriers were 1.289 (95% CI=1.027-1.618; P=0.096 for heterogeneity) and 1.168 (95% CI=1.062-1.284; P=0.231 for heterogeneity) for lung adenocarcinoma (2724 cases and 6591 controls). When stratified by smoking status, the pooled OR was 1.440 (95% CI=1.078-1.923; P=0.042 for heterogeneity) for the Pro allele carriers among smokers (1480 cases and 1414 controls). Although some statistical bias could not be eliminated, this meta-analysis suggests that the Pro allele is a low-penetrant risk factor for developing lung cancer. Additionally, we found that this phenomenon was more prominent in subgroups such as in Asians and Caucasians, in lung adenocarcinoma, or in smokers.

The value of diffusion-weighted imaging in assessing the ADC changes of tissues adjacent to breast carcinoma

Background

To define a threshold value of apparent diffusion coefficient (ADC) with which malignant breast lesions can be distinguished from benign lesions, and to evaluate the ADC change of peri-tumor tissue in breast carcinoma by echo planar-diffusion weighted imaging (EPI-DWI).

Methods

57 breast lesions were scanned by routine MRI and EPI-DWI. The ADC values were compared between malignant and benign lesions. The sensitivity and specificity of EPI-DWI and the threshold ADC value were evaluated by Receiver Operating Characteristic curve (ROC). The ADC values of malignant lesion and layered peri-tumor tissues (from innermost layer 1 to outermost layer 4 with 5 mm every layer) in different directions were compared and the ADC values among different layers were compared.

Results

The ADC value of 35 malignant lesions was statistically lower than that of 22 benign lesions (P < 0.05). In ROC curve, the threshold value was 1.24 +/- 0.25*10E-3 mm²/s (b = 500) or 1.20 +/- 0.25*10E-3 mm²/s (b = 1000). The ADC value of malignant lesions was statistically lower than that of peri-tumor tissues in different directions (P < 0.05). For peri-tumor tissues, the ADC values increased gradually from layer 1 to layer 4 and there was a significant difference between the ADC values of layer 1 and layer 2 (P < 0.05); while from layer 2 outwards, there was no statistical difference among different layers.

Conclusion

ADC value was a sensitive and specific parameter that could help to differentiate benign and malignant breast lesions. ADC changes in tissues adjacent to breast carcinoma could be detected by EPI-DWI, which made EPI-DWI a promising method for helping to determine surgical scope of breast carcinoma.

Microsatellite instability at a tetranucleotide repeat in type I endometrial carcinoma

BACKGROUND

Microsatellite instability (MSI) at tri- or tetranucleotide repeat markers (elevated microsatellite alterations at selected tetranucleotide repeat, EMAST) has been recently described. But, the underlying genetic mechanism of EMAST is unclear. This study was to investigate the prevalence of EMAST, in type I endometrial carcinoma, and to determine the correlation between the MSI status and mismatch repair genes (MMR) or p53.

METHODS

We examined the 3 mono-, 3 di-, and 6 tetranucleotide repeat markers by PCR in 39 cases of type I endometrial carcinoma and performed the immunohistochemistry of hMSH2, hMLH1, and p53 protein.

RESULTS

More than two MSI at mono- and dinucleotide repeat markers was noted in 8 cases (MSI-H, 20.5%). MSI, at a tetranucleotide repeat, was detected in 15 cases (EMAST, 38.5%). In remaining 16 cases, any MSI was not observed. (MSS, 42.1%), MSI status was not associated with FIGO stage, grade or depth of invasion. The absence of expression of either one of both hMSH2 or hMLH1 was noted in seven (87.5%) of eight MSI-H tumors, one (6.3%) of 16 MSS tumors, and five (33.3%) of 15 EMAST tumors. (p = 0.010) The expression of p53 protein was found in one (12.5%) of eight MSI-H tumors, five (31.3%) of 16 MSS tumors, and seven of 15 EMAST tumors. (p = 0.247)

CONCLUSION

Our results showed that about 38.5% of type I endometrial carcinomas exhibited EMAST, and that EMAST was rarely associated with alteration of hMSH2 or hMLH1.

The correlations between HPV16 infection and expressions of c-erbB-2 and bcl-2 in breast carcinoma

Breast carcinoma (BC) is a prevalent malignant tumour occurring in women. Many studies have indicated the role of human papilloma virus type 16 (HPV16) in the pathogenesis of BC; however, the correlations of HPV16 infection with the clinicopathologic features of BC and the expressions of c-erbB-2 and bcl-2 have not yet been elucidated. In this study, HPV16 was detected by amplifying the HPV16 E6 gene by the polymerase chain reaction method, and the expressions of c-erbB-2 and bcl-2 in 40 BCs and 20 normal breast tissue samples, obtained from Shaanxi Province, were examined using the streptavidin-peroxidase method with monoclonal antibodies specific to c-erbB-2 and bcl-2. The infection rate of HPV16 E6 and the positive expression rate of c-erbB-2 were significantly higher in the BCs than in the normal tissues (HPV16 E6: 60% vs. 5%; c-erbB-2: 42.5% vs. 5%, P < 0.05). However, the positive expression rate of bcl-2 was significantly lower in the BCs than in the normal tissues (67.5% vs. 95%, P < 0.05). The infection rate of HPV16 did not correlate with any of the pathological features observed (P > 0.05). HPV16 infection correlated with bcl-2 expression (P = 0.015) but not with c-erbB-2 expression (P = 0.747) in the BCs. Interestingly, HPV16 infection correlated with bcl-2 expression in grade I BCs (P = 0.018) but not in grade II-III BCs (P = 0.633). Our data suggest that HPV16 infection is correlated with bcl-2 expression in BCs.

New alternative phosphorylation sites on the cyclin dependent kinase 1/cyclin a complex in p53-deficient human cells treated with etoposide: possible association with etoposide-induced apoptosis

Cell cycle arrest is a major cellular response to DNA damage preceding the decision to repair or die. Many malignant cells have non-functional p53 rendering them more "aggressive" in nature. Arrest in p53-negative cells occurs at the G2M cell cycle checkpoint. Failure of DNA damaged cells to arrest at G2 results in entry into mitosis and potential death through aberrant mitosis and/or apoptosis. The pivotal kinase regulating the G2M checkpoint is Cdk1/cyclin B whose activity is controlled by phosphorylation. The p53-negative myeloid leukemia cell lines K562 and HL-60 were used to determine Cdk1 phosphorylation status during etoposide treatment. Cdk1 tyrosine 15 phosphorylation was associated with G2M arrest, but not with cell death. Cdk1 tyrosine 15 phosphorylation also led to suppression of nuclear cyclin B-associated Cdk1 kinase activity. However cell death, associated with broader tyrosine phosphorylation of Cdk1 was not attributed to tyrosine 15 alone. This broader phosphoryl isoform of Cdk1 was associated with cyclin A and not cyclin B. Alternative phosphorylations sites were predicted as tyrosines 4, 99 and 237 by computer analysis. No similar pattern was found on Cdk2. These findings suggest novel Cdk1 phosphorylation sites, which appear to be associated with p53-independent cell death following etoposide treatment.

Docosahexaenoic Acid (DHA), a Primary Tumor Suppressive Omega-3 Fatty Acid, Inhibits Growth of Colorectal Cancer Independent of p53 Mutational Status

Human colon carcinoma COLO 205, carrying wild type p53, grown subcutaneously in athymic mice was inhibited 80% by a high fat menhaden oil diet containing a mixture of omega-3 fatty acids compared to the low fat corn oil diet containing omega-6 fatty acids. Feeding a high fat diet of golden algae oil containing docosahexaenoic acid (DHA) as the sole long chain omega-3 fatty acid resulted in 93% growth inhibition. Similar findings were previously reported for WiDr colon carcinoma containing mutated p53 (His237). In vitro, 125 muM DHA inhibited COLO 205 growth by 81%, WiDr by 42%, while eicosapentaenoic acid (EPA) marginally inhibited growth of both lines by approximately 30%. DHA inhibited cell proliferation by 41% in WiDr but did not significantly inhibit proliferation in COLO 205. Cell cycle analysis revealed that DHA arrested cell cycle at Resting/Gap 1 (G0/G1 phase) in WiDr and at Gap 2/Mitosis (G2/M) phase in COLO 205. DHA induced apoptosis in COLO 205 but not in WiDr, and EPA did not induce apoptosis in either line. Taken together, these findings suggest DHA is the primary tumor suppressive omega-3 fatty acid in vivo and in vitro and inhibits cancer growth by p53 dependent and independent pathways, while the marginal inhibition by EPA is p53 independent.

Detection of p53 Protein in Induced Sputum After Occupational Exposure to Crystalline Silica

OBJECTIVE

To examine the possibility of detecting p53 protein in the supernatant of induced sputum (IS) of workers exposed to crystalline silica.

METHODS

Personal interviews were used to obtain demographic data, occupational and exposure histories, and health habits of the study participants. Sputum samples were collected from all subjects.

RESULTS

The all-male study cohort included 35 workers (mean age 43.8 years) exposed to silica and 7 unexposed workers (34.7 years, P < 0.05). The mean duration of exposure was 13.4 years, and the range of exposure levels to silica was 0.02 to 0.33 ppm. The mean level of p53 protein was higher in the exposed group compared with in the unexposed group (76.47 pg/mL and 62.43 pg/mL, respectively).

CONCLUSIONS

p53 may serve as a biomarker to identify workers at high risk for developing pulmonary malignancies. IS can detect p53 protein in sputum.

Fast, hungry and unstable: finding the Achilles' heel of small-cell lung cancer

Over 95% of patients with small-cell lung cancer (SCLC) die within five years of diagnosis. The standard of care and the dismal prognosis for this disease have not changed significantly over the past 25 years. Some of the characteristics of SCLC that have defined it as a particularly virulent form of cancer -- rapid proliferation, excessive metabolic and angiogenic dependence, apoptotic imbalance and genetic instability -- are now being pursued as tumor-specific targets for intervention both in preclinical and early phase clinical studies. Here, we summarize areas of ongoing anti-cancer drug development, including classes of agents that target essential pathways regulating proliferation, angiogenesis, apoptotic resistance, chromosomal and protein stability, and cell-cell and cell-matrix interaction.

Methionine inhibits cellular growth dependent on the p53 status of cells

BACKGROUND

Methionine, an essential amino acid, is important for normal growth and development, as it is required for both protein and polyamine synthesis as well as in methylation reactions. It has been reported that high concentrations of methionine inhibit cellular growth and gene expression in the human breast tumor-derived MCF-7 cells. These effects are thought to be mediated by the modulation of p53. However, the generalizability of this observation and the precise role of p53 in methionine-induced growth suppression needs to be determined.

METHODS

To determine if the inhibition of cell growth by methionine applies to other cell lines and to characterize further the role of p53 in methionine-induced growth suppression, we have assessed the effects of methionine on cellular growth and proliferation and p53 expression in cells expressing native p53, eg, breast cancer MCF-7 cells and prostate cancer LNCaP cells, and also in cells expressing a mutated (point) form of p53, eg, prostate cancer DU-145 cells. These cell lines were treated with varying concentrations of L-methionine. The effects of L-methionine on cell growth were assayed by using cell viability assays and immunostaining for Ki-67, a cell proliferation marker. The effects of methionine on p53 expression were assessed by using reverse transcriptase-polymerase chain reaction (RT-PCR), immunohistochemistry, and Western blot analysis. The role of p53 in L-methionine-mediated growth suppression was evaluated using short-interference RNA for p53 (siRNA-p53), immunoprecipitation, and direct DNA sequencing.

RESULTS

We demonstrated that methionine at a concentration of 1 to 5 mg/mL inhibited the growth of both MCF-7 and LNCaP cells. In association with the inhibition of growth, methionine also inhibited native p53 expression at the mRNA and protein levels, respectively. Furthermore, transfection with siRNA-p53, to knock down p53 expression, increased cell growth and proliferation of the LNCaP cells even when they were exposed to methionine. In contrast, the same treatment did not diminish growth or proliferation of the DU-145 cells. Also, the expression of mutated p53 at the mRNA or protein levels was not altered.

CONCLUSION

Our results extend a prior observation to other cell lines and demonstrate that high concentrations of methionine suppress the expression of native but not mutated p53. These inhibitory effects on cellular growth are, in part, due to inhibition of cellular proliferation probably via a p53-dependent pathway.

Mutations in Exons 6 and 7 of TP53 Gene Correlate Positively with Serum Tumor Necrosis Factor Alpha Independent of Microsatellite Instability in BAT26 Gene in Egyptian Patients with Endometrial Carcinoma

Abnormalities in the TP53 gene are the most frequent genetic alterations in human cancers. The role and mechanism of TP53 mutations have been well studied in many types of human cancer. Similarly, the presence of microsatellite instability (MSI) in the DNA mismatch repair system (hMSH2) may provide evidence of faulty DNA mismatch repair. One of the most important locations of MSI is the BAT26 gene. In addition, deranged serum cytokines, especially elevated levels of the tumor necrosis factor (TNF) alpha, have been found in many gynecological conditions.

Aims

The current study aimed at evaluating mutations in exons 6 and 7 of TP53 and the presence of microsatellite instability in BAT26 of the hMSH2 system in Egyptian patients with endometrial carcinoma. The study also evaluated whether there was a correlation between any of these genetic mutations/instability and the tissue expression of estrogen and progesterone receptors and the serum TNF-alpha level.

Patients and methods

The current study included 2 groups: a control group comprising 20 healthy women aged 52.21 ± 5.80 years attending the clinic for routine checkups and 40 patients with endometrial cancer aged 55.30 ± 6.21 years. Mutations in TP53 and BAT26 were evaluated using polymerase chain reaction–single-strand conformational polymorphism (PCR-SSCP) and automated sequencing while serum TNF-alpha was measured using an ELISA technique. Estrogen and progesterone receptor expression in biopsy tissue was evaluated using immunohistochemical staining.

Results

Seven of the 40 patients (17.5%) were positive for TP53 gene alterations in exon 6, while 9 patients (22.5%) were positive for TP53 alterations in exon 7. Cases positive for TP53 mutations had higher tumor stages. Ten patients (25%) showed MSI in BAT26. Nearly all patients with mutations in BAT26 had a strong family history for endometrial cancer (χ2=13.33, p<0.05). There was no positive correlation between the presence of MSI in the BAT26 gene and mutations in the TP53 gene or high serum TNF-alpha levels. Cases positive for TP53 mutations had a significantly higher level of TNF-alpha than cases negative for TP53 mutations (p<0.05). Cases showing mutations in exon 6 or 7 of TP53 showed a significantly higher intensity of immunohistochemical staining for estrogen and progesterone receptor expression in biopsy tissue than cases negative for mutations. (χ2=8.11, p<0.05).

Conclusion

Our results suggest that the development of endometrial carcinoma is probably mediated through a multi-step carcinogenesis pathway and mutation of TP53 does not necessarily result from the presence of microsatellite instability in BAT26. The high serum TNF-alpha levels detected in our patients may represent an immunological antitumor response that was particularly evident in cases positive for TP53 mutations.

The ERK cascade: a prototype of MAPK signaling

Sequential activation of protein kinases within the mitogen-activated protein kinase (MAPK) cascades is a common mechanism of signal transduction in many cellular processes. Four such cascades have been elucidated thus far, and named according to their MAPK tier component as the ERK1/2, JNK, p38MAPK, and ERK5 cascades. These cascades cooperate in transmitting various extracellular signals, and thus control cellular processes such as proliferation, differentiation, development, stress response, and apoptosis. Here we describe the classic ERK1/2 cascade, and concentrate mainly on the properties of MEK1/2 and ERK1/2, including their mode of regulation and their role in various cellular processes and in oncogenesis. This cascade may serve as a prototype of the other MAPK cascades, and the study of this cascade is likely to contribute to the understanding of mitogenic and other processes in many cell lines and tissues.

Two germ line polymorphisms of the tumour suppressor gene p53 may influence the biology of chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL) is characterised by the accumulation of mature B lymphocytes. Defects in the tumour suppressor gene p53 pathway are known to be important in CLL and p53 inactivation is associated with a particularly aggressive form of CLL. A single nucleotide polymorphism (SNP) in codon 72 of TP53 leads to a single amino acid change leading to a change in apoptotic potential and alters prognosis in squamous carcinomas. A polymorphism within intron 6 of TP53 has been postulated to alter the susceptibility to lung cancer. Our study looked at the influence of these two polymorphisms in a cohort of approximately 200 CLL patients. The codon 72 polymorphism A2/A2 genotype (homozygous arginine) was associated with an increased susceptibility to CLL and CD38 negativity but did not appear to influence other biological behaviour or clinical response. The intron 6 polymorphism A2/A2 genotype was strongly associated with early stage disease, CD38 negativity and a longer time to first treatment. The effect on time to treatment did not retain significance in multivariate analysis and the polymorphism did not predict for overall survival (OS). Detailed investigation of the complete TP53 genotype is warranted to further characterise the role of SNPs in p53 and their influence on CLL.

Role of metabolism and viruses in aflatoxin-induced liver cancer

The use of biomarkers in molecular epidemiology studies for identifying stages in the progression of development of the health effects of environmental agents has the potential for providing important information for critical regulatory, clinical and public health problems. Investigations of aflatoxins probably represent one of the most extensive data sets in the field and this work may serve as a template for future studies of other environmental agents. The aflatoxins are naturally occurring mycotoxins found on foods such as corn, peanuts, various other nuts and cottonseed and they have been demonstrated to be carcinogenic in many experimental models. As a result of nearly 30 years of study, experimental data and epidemiological studies in human populations, aflatoxin B(1) was classified as carcinogenic to humans by the International Agency for Research on Cancer. The long-term goal of the research described herein is the application of biomarkers to the development of preventative interventions for use in human populations at high-risk for cancer. Several of the aflatoxin-specific biomarkers have been validated in epidemiological studies and are now being used as intermediate biomarkers in prevention studies. The development of these aflatoxin biomarkers has been based upon the knowledge of the biochemistry and toxicology of aflatoxins gleaned from both experimental and human studies. These biomarkers have subsequently been utilized in experimental models to provide data on the modulation of these markers under different situations of disease risk. This systematic approach provides encouragement for preventive interventions and should serve as a template for the development, validation and application of other chemical-specific biomarkers to cancer or other chronic diseases.

p53 Mutations in human cholangiocarcinoma: a review

The reported mortality from intrahepatic bile duct tumours is increasing markedly in industrialised countries, for reasons that remain unknown. Inactivation of the tumour suppressor gene p53, is the commonest genetic abnormality in human cancer and has been implicated in the genesis of cholangiocarcinoma in various immunohistochemical and molecular epidemiological investigations, including gene sequencing studies. The structure and function of p53 and its role in linking cancer to specific carcinogens by way of mutational signatures is reviewed. The findings of previous p53 studies and their relevance in human cholangiocarcinoma are summarised.

Colorimetric approach to high-throughput mutation analysis

High-throughput genomic mutation screening for primary tumors has characteristically been expensive, labor-intensive, and inadequate to detect low levels of mutation in a background of wild-type signal. We present a new, combined PCR and colorimetric approach that is inexpensive, simple, and can detect the presence of 1% mutation in a background of wild-type. We compared manual dideoxy sequencing of p53 for eight lung cancer samples to a novel assay combining a primer extension step and an enzymatic colorimetric step in a 96-well plate with covalently attached oligonucleotide sequences. For every sample, we were able to detect the presence or absence of the specific mutation with a statistically significant difference between the sample optical density (OD) and the background OD, with a sensitivity and specificity of 100%. This assay is straightforward, accurate, inexpensive, and allows for rapid, high-throughput analysis of samples, making it ideal for genomic mutation or polymorphism screening studies in both clinical and research settings.

Expression of p53 and markers for apoptosis in breast tissue during long-term hormone therapy in cynomolgus monkeys

OBJECTIVE

The purpose of this study was to analyze the expression of p53 and markers for apoptosis in breast tissue during long-term hormone therapy in cynomolgus monkeys.

STUDY DESIGN

Sixty oophorectomized macaques were randomized to receive tibolone, conjugated equine estrogens (CEE), CEE+medroxyprogesterone acetate (MPA), or no hormonal treatment. Breast tissue was collected at necropsy after 2 years, and stained for p53, p21, and cleaved caspase-3.

RESULTS

Differences were seen between treatment groups. The expression of p53 and caspase-3 was significantly lower in tibolone-treated animals (P<.01). Levels of p53 and caspase-3 were lower in the combined treatment group (CEE+MPA) when compared to both estrogen only and control groups.

CONCLUSION

Alternative regimens for hormonal therapy seem to have different effects on p53 expression and apoptotic activity within the breast. A combined effect of increased proliferation and decreased apoptosis could be one possible mechanism to explain an increased risk for breast cancer.

DNA microarrays on a dendron-modified surface improve significantly the detection of single nucleotide variations in the p53 gene

Selectivity and sensitivity in the detection of single nucleotide polymorphisms (SNPs) are among most important attributes to determine the performance of DNA microarrays. We previously reported the generation of a novel mesospaced surface prepared by applying dendron molecules on the solid surface. DNA microarrays that were fabricated on the dendron-modified surface exhibited outstanding performance for the detection of single nucleotide variation in the synthetic oligonucleotide DNA. DNA microarrays on the dendron-modified surface were subjected to the detection of single nucleotide variations in the exons 5-8 of the p53 gene in genomic DNAs from cancer cell lines. DNA microarrays on the dendron-modified surface clearly discriminated single nucleotide variations in hotspot codons with high selectivity and sensitivity. The ratio between the fluorescence intensity of perfectly matched duplexes and that of single nucleotide mismatched duplexes was >5-100 without sacrificing signal intensity. Our results showed that the outstanding performance of DNA microarrays fabricated on the dendron-modified surface is strongly related to novel properties of the dendron molecule, which has the conical structure allowing mesospacing between the capture probes. Our microarrays on the dendron-modified surface can reduce the steric hindrance not only between the solid surface and target DNA, but also among immobilized capture probes enabling the hybridization process on the surface to be very effective. Our DNA microarrays on the dendron-modified surface could be applied to various analyses that require accurate detection of SNPs.

Low density DNA microarray for detection of most frequent TP53 missense point mutations

Background

We have developed an oligonucleotide microarray (genosensor) utilizing a double tandem hybridization technique to search for 9 point mutations located in the most frequently altered codons of the TP53 gene. Isolated and multiplexed PCR products, 108 and 92 bp long, from exons 7 and 8, respectively, were obtained from 24 different samples. Single-stranded target DNA was then prepared from isolated or multiplexed PCR products, through cyclic DNA synthesis. Independent ssDNA's were annealed with the corresponding pairs of labeled stacking oligonucleotides to create partially duplex DNA having a 7-nt gap, which contains the sequence that will be interrogated by the capture probes forming double tandem hybridization. In the case of multiplexed ssPCR products, only two stacking oligonucleotides were added per target, therefore the gap for the PCR products having two consecutive codons to be interrogated in exon 7 was 12 nt long, so only single tandem hybridization was produced with these respective probes.

Results

18 codon substitutions were found by DNA sequencing. In 13 of them a perfect correlation with the pattern of hybridization was seen (In 5 no signal was seen with the wt probe while a new signal was seen with the appropriate mutant probe, and in 8 more, as expected, no signal was seen with any probe due to the absence of the corresponding probe in the array). In 3 other cases a mutation was falsely suggested by the combination of the absence of the wild type signal along with a false signal in the other probe. In the other 2 cases the presence of the mutation was not detected due to the production of a false hybridization signal with the wild type probe. In both cases (false mutation or no mutation detected) relatively stable mismatched target/probe duplexes should be formed. These problems could be avoided by the addition of probes to improve the performance of the array.

Conclusion

Our results demonstrate that a simple TP53 microarray employing short (7-mer) probes, used in combination with single or double tandem hybridization approach and a simple or multiplex target preparation method, can identify common TP53 missense mutations from a variety of DNA sources with good specificity.

Protein quadratic indices of the "macromolecular pseudograph's alpha-carbon atom adjacency matrix". 1. Prediction of Arc repressor alanine-mutant's stability

This report describes a new set of macromolecular descriptors of relevance to protein QSAR/QSPR studies, protein's quadratic indices. These descriptors are calculated from the macromolecular pseudograph's alpha-carbon atom adjacency matrix. A study of the protein stability effects for a complete set of alanine substitutions in Arc repressor illustrates this approach. Quantitative Structure-Stability Relationship (QSSR) models allow discriminating between near wild-type stability and reduced-stability A-mutants. A linear discriminant function gives rise to excellent discrimination between 85.4% (35/41)and 91.67% (11/12) of near wild-type stability/reduced stability mutants in training and test series, respectively. The model's overall predictability oscillates from 80.49 until 82.93, when n varies from 2 to 10 in leave-n-out cross validation procedures. This value stabilizes around 80.49% when n was > 6. Additionally, canonical regression analysis corroborates the statistical quality of the classification model (Rcanc = 0.72, p-level <0.0001). This analysis was also used to compute biological stability canonical scores for each Arc A-mutant. On the other hand, nonlinear piecewise regression model compares favorably with respect to linear regression one on predicting the melting temperature (tm)of the Arc A-mutants. The linear model explains almost 72% of the variance of the experimental tm (R = 0.85 and s = 5.64) and LOO press statistics evidenced its predictive ability (q2 = 0.55 and scv = 6.24). However, this linear regression model falls to resolve t(m) predictions of Arc A-mutants in external prediction series. Therefore, the use of nonlinear piecewise models was required. The tm values of A-mutants in training (R = 0.94) and test(R = 0.91) sets are calculated by piecewise model with a high degree of precision. A break-point value of 51.32 degrees C characterizes two mutants' clusters and coincides perfectly with the experimental scale. For this reason, we can use the linear discriminant analysis and piecewise models in combination to classify and predict the stability of the mutants' Arc homodimers. These models also permit the interpretation of the driving forces of such a folding process. The models include protein's quadratic indices accounting for hydrophobic (z1), bulk-steric (z2), and electronic (z3) features of the studied molecules. Preponderance of z1 and z3 over z2 indicates the higher importance of the hydrophobic and electronic side chain terms in the folding of the Arc dimer. In this sense, developed equations involve short-reaching (k < or = 3), middle- reaching (3 < k < or = 7) and far-reaching (k= 8 or greater) z1, 2, 3-protein's quadratic indices. This situation points to topologic/topographic protein's backbone interactions control of the stability profile of wild-type Arc and its A-mutants. Consequently, the present approach represents a novel and very promising way to mathematical research in biology sciences.

Redox-cycling of anthracyclines by thioredoxin system: increased superoxide generation and DNA damage

Anthracyclines such as doxorubicin and daunomycin undergo bioreductive activation by redox-cycling, and this is associated with generation of reactive oxygen species. Toxicity of anthracyclines is attributed to DNA intercalation by an anthracycline semiquinone radical that is generated via redox-cycling. Flavoprotein enzymes catalyze the bioreductive activation of anthracyclines. Thioredoxin reductase (TR), which is also a flavoprotein enzyme, participates in bioreductive activation of anthracyclines. In the present study we showed that addition of E. coli thioredoxin (Trx) enhances the rate of superoxide production by E. coli TR in the presence of anthracyclines. The superoxide generated in this redox-cycling process induced DNA damage as determined by an in vitro plasmid DNA damage assay. In addition, Trx-SH enhanced the activity of cyto-chrome P450 reductase and the redox-cycling of anthracyclines independently of NADPH. Furthermore,when A549 cells were incubated with E. coli Trx followed by doxorubicin treatment, increased levels of ROS generation were observed. Taken together, these results show a novel property of the Trx system in bioreductive activation of anthracyclines.