Tumor suppressor genes: the puzzle and the promise

Effect of epigenetic changes in hypoxia induced factor (HIF) gene across cancer types

Cancer hypoxia, a crucial characteristic of malignancy, ranging from practically non-hypoxic to severe, impacts gene expression, metabolism and mechanisms associated with tumor formation serves as a key obstacle in cancer therapy. It triggers a complex network of cell signaling pathways, such as the NF-κB, PI3K, mTOR/AKT,MAPK, HIF and their associated genes regulating the effects of the same. The onset and advancement of cancer are attributed to genetic and epigenetic modifications which are intrinsically related. Off late, it has been observed that in disease progression, the epigenetic modifications lead to gene mutations that in turn alter the epigenome, presenting a major hurdle in fabricating treatment strategies. However, theprogress in science and technology has led to the emergence of various surfacing omics and multi-view clustering algorithms, which offer unparalleled prospects for further subtyping cancers, enhancing the prognosis and treatment results of these subtypes, and comprehending crucial pathophysiological mechanisms across diverse molecular strata. Multi-omics has allowed scientists to gain a more comprehensive understanding of the various ways that cellular malfunction can lead to cancer. So, it becomes of utmost importance to firstly understand the epigenetic changes taking place in tumor hypoxia at gene level. This review sheds light on the role of HIF gene in hypoxic milieu and its relationship with mechanisms of cancer epigenetics. It further glances as to how omics approach can be used to study the oncogenic cellular changes and how bioinformatic tools aid in identification of complex gene networks involved in disease progression. Lastly, it glimpses through the benefits and shortcomings of the existing epi drug therapy and how it can be used in developing novel treatment options.

ITIH5 as a multifaceted player in pancreatic cancer suppression, impairing tyrosine kinase signaling, cell adhesion and migration

Inter-alpha-trypsin inhibitor heavy chain 5 (ITIH5) has been identified as a metastasis suppressor gene in pancreatic cancer. Here, we analyzed ITIH5 promoter methylation and protein expression in The Cancer Genome Atlas (TCGA) dataset and three tissue microarray cohorts (n = 618), respectively. Cellular effects, including cell migration, focal adhesion formation and protein tyrosine kinase activity, induced by forced ITIH5 expression in pancreatic cancer cell lines were studied in stable transfectants. ITIH5 promoter hypermethylation was associated with unfavorable prognosis, while immunohistochemistry demonstrated loss of ITIH5 in the metastatic setting and worsened overall survival. Gain-of-function models showed a significant reduction in migration capacity, but no alteration in proliferation. Focal adhesions in cells re-expressing ITIH5 exhibited a smaller and more rounded phenotype, typical for slow-moving cells. An impressive increase of acetylated alpha-tubulin was observed in ITIH5-positive cells, indicating more stable microtubules. In addition, we found significantly decreased activities of kinases related to focal adhesion. Our results indicate that loss of ITIH5 in pancreatic cancer profoundly affects its molecular profile: ITIH5 potentially interferes with a variety of oncogenic signaling pathways, including the PI3K/AKT pathway. This may lead to altered cell migration and focal adhesion formation. These cellular alterations may contribute to the metastasis-inhibiting properties of ITIH5 in pancreatic cancer.

Phospholipase A and acyltransferase 4/retinoic acid receptor responder 3 at the intersection of tumor suppression and pathogen restriction

Phospholipase A and acyltransferase (PLAAT) 4 is a class II tumor suppressor with phospholipid metabolizing abilities. It was characterized in late 2000s, and has since been referred to as 'tazarotene-induced gene 3' (TIG3) or 'retinoic acid receptor responder 3' (RARRES3) as a key downstream effector of retinoic acid signaling. Two decades of research have revealed the complexity of its function and regulatory roles in suppressing tumorigenesis. However, more recent findings have also identified PLAAT4 as a key anti-microbial effector enzyme acting downstream of interferon regulatory factor 1 (IRF1) and interferons (IFNs), favoring protection from virus and parasite infections. Unveiling the molecular mechanisms underlying its action may thus open new therapeutic avenues for the treatment of both cancer and infectious diseases. Herein, we aim to summarize a brief history of PLAAT4 discovery, its transcriptional regulation, and the potential mechanisms in tumor prevention and anti-pathogen defense, and discuss potential future directions of PLAAT4 research toward the development of therapeutic approaches targeting this enzyme with pleiotropic functions.

Targeting p53 pathways: mechanisms, structures, and advances in therapy

The TP53 tumor suppressor is the most frequently altered gene in human cancers, and has been a major focus of oncology research. The p53 protein is a transcription factor that can activate the expression of multiple target genes and plays critical roles in regulating cell cycle, apoptosis, and genomic stability, and is widely regarded as the "guardian of the genome". Accumulating evidence has shown that p53 also regulates cell metabolism, ferroptosis, tumor microenvironment, autophagy and so on, all of which contribute to tumor suppression. Mutations in TP53 not only impair its tumor suppressor function, but also confer oncogenic properties to p53 mutants. Since p53 is mutated and inactivated in most malignant tumors, it has been a very attractive target for developing new anti-cancer drugs. However, until recently, p53 was considered an "undruggable" target and little progress has been made with p53-targeted therapies. Here, we provide a systematic review of the diverse molecular mechanisms of the p53 signaling pathway and how TP53 mutations impact tumor progression. We also discuss key structural features of the p53 protein and its inactivation by oncogenic mutations. In addition, we review the efforts that have been made in p53-targeted therapies, and discuss the challenges that have been encountered in clinical development.

Advances in Nanotechnology for Cancer Immunoprevention and Immunotherapy: A Review

One of the most effective cancer therapies, cancer immunotherapy has produced outstanding outcomes in the field of cancer treatment. However, the cost is excessive, which limits its applicability. A smart way to address this issue would be to apply the knowledge gained through immunotherapy to develop strategies for the immunoprevention of cancer. The use of cancer vaccines is one of the most popular methods of immunoprevention. This paper reviews the technologies and processes that support the advantages of cancer immunoprevention over traditional cancer immunotherapies. Nanoparticle drug delivery systems and nanoparticle-based nano-vaccines have been employed in the past for cancer immunotherapy. This paper outlines numerous immunoprevention strategies and how nanotechnology can be applied in immunoprevention. To comprehend the non-clinical and clinical evaluation of these cancer vaccines through clinical studies is essential for acceptance of the vaccines.

Multi-functional self-assembled nanoparticles for pVEGF-shRNA loading and anti-tumor targeted therapy

Although RNA interference (RNAi) technology shows great potential in cancer treatment, the tumor target delivery and sufficient cytosolic transport of RNAi agents are still the main obstacles for its clinical applications. Herein, we report a functional supramolecular self-assembled nanoparticle vector for RNAi agent loading and tumor target therapy. Molecular block adamantane-grafted poly(ethylene glycol) (Ad-PEG) was modified with epidermal growth factor receptor (EGFR)-specific binding ligand GE11 or pH-sensitive fusogenic peptide GALA and then used for self-assembly with cyclodextrin-grafted branched polyethylenimine (CD-PEI), adamantane-grafted polyamidoamine dendrimer (Ad-PAMAM), and plasmid DNA containing a small hairpin RNA expression cassette against vascular endothelial growth factor (VEGF) into functional DNA-loaded supramolecular nanoparticles (GE11&GALA-pshVEGF@SNPs) based on molecular recognition and charge interaction. These functional peptides facilitated the target cell binding, internalization, and endosomal escape of GE11&GALA-pshVEGF@SNPs, resulting in increased reporter gene expression and efficient targeted gene silencing. The systemic delivery of the GE11&GALA-pshVEGF@SNPs can efficiently downregulate the intratumoral VEGF protein levels, reduce blood vessel formation, and significantly inhibit A549 xenograft tumor growth. These results reveal the potential of these multifunctional self-assembled nanoparticles as a nucleic acid drug delivery system for the treatment of lung cancer.

Pan-Cancer and Single-Cell Modeling of Genomic Alterations Through Gene Expression

Cancer is a disease often characterized by the presence of multiple genomic alterations, which trigger altered transcriptional patterns and gene expression, which in turn sustain the processes of tumorigenesis, tumor progression, and tumor maintenance. The links between genomic alterations and gene expression profiles can be utilized as the basis to build specific molecular tumorigenic relationships. In this study, we perform pan-cancer predictions of the presence of single somatic mutations and copy number variations using machine learning approaches on gene expression profiles. We show that gene expression can be used to predict genomic alterations in every tumor type, where some alterations are more predictable than others. We propose gene aggregation as a tool to improve the accuracy of alteration prediction models from gene expression profiles. Ultimately, we show how this principle can be beneficial in intrinsically noisy datasets, such as those based on single-cell sequencing.

Genetic polymorphisms of TP53 Arg72Pro and Pro47Ser among Egyptian patients with colorectal carcinoma

BACKGROUND

Previous reports demonstrated the role of TP53 gene polymorphisms with CRC risk among several ethnic populations. The purpose of this study is to assess the association of the TP53 Arg72Pro and Pro47Ser variants with CRC risk among Egyptian patients.

SUBJECTS AND METHODS

This work was conducted on 120 unrelated CRC Egyptian patients who were compared to 140 healthy controls. DNA was genotyped for these variants using the PCR-RFLP technique.

RESULTS

CRC patients observed a significant association of the rare genotype of TP53 Arg72Pro polymorphism compared with healthy controls. On the contrast, all genetic models showed no statistical association of TP53 Pro47Ser polymorphism among CRC patients compared with healthy controls. On the contrast, CRC patients of the TP53 gene polymorphisms indicated no significant difference regarding their clinical and laboratory markers.

CONCLUSIONS

Our findings indicate a strong association with TP53 Arg72Pro variant within increased risk of CRC among Egyptian patients.

Integrative analysis of common genes and driver mutations implicated in hormone stimulation for four cancers in women

Cancer is one of the leading cause of death of women worldwide, and breast, ovarian, endometrial and cervical cancers contribute significantly to this every year. Developing early genetic-based diagnostic tools may be an effective approach to increase the chances of survival and provide more treatment opportunities. However, the current cancer genetic studies are mainly conducted independently and, hence lack of common driver genes involved in cancers in women. To explore the potential common molecular mechanism, we integrated four comprehensive literature-based databases to explore the shared implicated genetic effects. Using a total of 460 endometrial, 2,068 ovarian, 2,308 breast and 537 cervical cancer-implicated genes, we identified 52 genes which are common in all four types of cancers in women. Furthermore, we defined their potential functional role in endogenous hormonal regulation pathways within the context of four cancers in women. For example, these genes are strongly associated with hormonal stimulation, which may facilitate rapid diagnosis and treatment management decision making. Additional mutational analyses on combined the cancer genome atlas datasets consisting of 5,919 gynaecological and breast tumor samples were conducted to identify the frequently mutated genes across cancer types. For those common implicated genes for hormonal stimulants, we found that three quarter of 5,919 samples had genomic alteration with the highest frequency in MYC (22%), followed by NDRG1 (19%), ERBB2 (14%), PTEN (13%), PTGS2 (13%) and CDH1 (11%). We also identified 38 hormone related genes, eight of which are associated with the ovulation cycle. Further systems biology approach of the shared genes identified 20 novel genes, of which 12 were involved in the hormone regulation in these four cancers in women. Identification of common driver genes for hormone stimulation provided an unique angle of involving the potential of the hormone stimulants-related genes for cancer diagnosis and prognosis.

Bronchoscopic Therapies for Peripheral Lung Malignancies

Current advances in guided bronchoscopy methods permit minimally invasive access to essentially any area of the lungs. This provides a potential means to treat patients with localized lung malignancies who might not otherwise tolerate conventional treatment, which commonly relies on surgical resection. Ablation methods have long been used for bronchoscopic treatment of central airway malignancies and percutaneous treatment of peripheral lung cancer. This article reviews ablation technologies being adapted for use with guided bronchoscopy and the current state of investigation for the treatment of peripheral lung malignancies.

Key rates for the grades and transformation ability of glioma: model simulations and clinical cases

Tumor progression to higher grade is a fundamental property of cancer. The malignant advancement of the pathological features may either develop during the later stages of cancer growth (natural evolution) or it may necessitate new mutations or molecular events that alter the rates of growth, dispersion, or neovascularization (transformation). Here, we model the pathological and radiological features of grades 2-4 gliomas at the times of diagnosis and death and study grade development and the progression to higher grades. We perform a retrospective review of clinical cases based on model predictions. Simulations uncover two unusual patterns of glioma progression, which are supported by clinical cases: (1) some grades 2 and 3 gliomas lack the ability of progression to higher grades, and (2) grade 3 glioma may evolve to GBM in a few weeks. All 13 gliomas that recurred at the same grade carry either the IDH1-R132H or the ATRX mutation. All (five of five) grade 3 tumors are 1p/19q co-deleted, IDH1-R132H mutated and ATRX wt. Furthermore, three of seven grade 2 gliomas are both IDH1-R132H mutated and ATRX mutated. Simulations replicate the good prognosis of secondary GBM. The results support the hypothesis that constant rates of dispersion, proliferation, and angiogenesis prescribe either a natural evolution or the inability to progress to higher grades. Furthermore, the accrual of molecular events that change a tumor's ability to infiltrate, proliferate or neovascularize may transform the glioma either into a more aggressive tumor at the same grade or elevate its grade.

The TP53 gene rs1042522 C>G polymorphism and neuroblastoma risk in Chinese children

TP53, a tumor suppressor gene, plays a critical role in cell cycle control, apoptosis, and DNA damage repair. Previous studies have indicated that the TP53 gene Arg72Pro (rs1042522 C>G) polymorphism is associated with susceptibility to various types of cancer. We evaluated the association of the TP53 gene rs1042522 C>G polymorphism with neuroblastoma susceptibility in a hospital-based study among the Chinese Han population. Enrolled were 256 patients and 531 controls. Odds ratios (ORs) and 95% confidence intervals (CIs) generated using logistic regression models were used to determine the strength of the association of interest. No association was detected between rs1042522 C>G polymorphism and neuroblastoma risk. In our stratification analysis of age, gender, sites of origin, and clinical stages, we observed that subjects with rs1042522 CG/GG genotypes had a lower risk of developing neuroblastoma in the mediastinum (Adjusted OR=0.52, 95% CI=0.33-0.82, P=0.005) than those carrying the CC genotype. These results indicate that TP53 gene rs1042522 C>G polymorphism may exert a weak and site-specific effect on neuroblastoma risk in Southern Chinese children and warrant further confirmation.

Association between TP53 gene Arg72Pro polymorphism and Wilms' tumor risk in a Chinese population

Wilms' tumor is one of the most prevalent pediatric malignancies, ranking fourth in childhood cancer worldwide. TP53 is a critical tumor suppressor gene, which encodes a 53 kDa protein, p53. The p53 functions to protect against cancer by regulating cell cycle and apoptosis and maintaining DNA integrity. TP53 gene is highly polymorphic. Several TP53 gene polymorphisms have been considered to be associated with cancer risk. Of them, a nonsynonymous polymorphism, Arg72Pro (rs1042522 C>G), has been most extensively studied for the association with cancer risk; however, few studies have investigated its effect on Wilms' tumor. Because of the central role of p53 in cell cycle control, the TP53 gene Arg72Pro polymorphism is also a good potential candidate predisposition locus for this pediatric cancer. We genotyped this polymorphism in 145 patients and 531 cancer-free controls recruited from Chinese children by Taqman methodology. Overall, our result suggested a lack of association between the TP53 gene Arg72Pro polymorphism and Wilms' tumor. In the stratified analysis, we found that carriers of CG/GG genotypes had a significantly increased Wilms' tumor risk in children not older than 18 months (adjusted odds ratio =2.04, 95% confidence interval =1.003-4.13, P=0.049) compared with CC genotype carriers. Our study indicated that the TP53 gene Arg72Pro polymorphism may have a weak, age-related effect on Wilms' tumor risk in Chinese children. These findings need further validations in other populations with larger sample size.

Chronic Inflammation and Breast Pathology: A Theoretical Model

Breast cell pathology results from biochemical and molecular changes that culminate in the cell’s loss of functional responsiveness. The epithelial cell compartment in the breast ductal system is the site of approximately 98% of malignant proliferations, and it is from within these cells that the first biochemical signal of change may be expressed as an inflammatory response. Inflammation may be represented by biomarkers of early pathologic changes in breast cells and be associated with risk for the development of breast cancer. A theoretical model of the inflammatory process is proposed showing predictive linkages among stimuli in the breast microenvironment and the development of breast pathology, in particular, breast cancer. This model fuels intervention concepts that may prevent malignant breast health outcomes.

Splenic gene expression profiling in White Leghorn layer inoculated with the Salmonella enterica serovar Enteritidis

Salmonella enterica serovar Enteritidis (SE) is a foodborne pathogen that can threaten human health through contaminated poultry products. Live poultry, chicken eggs and meat are primary sources of human salmonellosis. To understand the genetic resistance of egg-type chickens in response to SE inoculation, global gene expression in the spleen of 20-week-old White Leghorn was measured using the Agilent 4 × 44 K chicken microarray at 7 and 14 days following SE inoculation (dpi). Results showed that there were 1363 genes significantly differentially expressed between inoculated and non-inoculated groups at 7 dpi (I7/N7), of which 682 were up-regulated and 681 were down-regulated genes. By contrast, 688 differentially expressed genes were observed at 14 dpi (I14/N14), of which 371 were up-regulated genes and 317 were down-regulated genes. There were 33 and 28 immune-related genes significantly differentially expressed in the comparisons of I7/N7 and I14/N14 respectively. Functional annotation revealed that several Gene Ontology (GO) terms related to immunity were significantly enriched between the inoculated and non-inoculated groups at 14 dpi but not at 7 dpi, despite a similar number of immune-related genes identified between I7/N7 and I14/N14. The immune response to SE inoculation changes with different time points following SE inoculation. The complicated interaction between the immune system and metabolism contributes to the immune responses to SE inoculation of egg-type chickens at 14 dpi at the onset of lay. GC, TNFSF8, CD86, CD274, BLB1 and BLB2 play important roles in response to SE inoculation. The results from this study will deepen the current understanding of the genetic response of the egg-type chicken to SE inoculation at the onset of egg laying.

Tumor suppressor genes associated with drug resistance in ovarian cancer (review)

Ovarian cancer is a fatal gynecological cancer and a major cause of cancer-related mortality worldwide. The main limitation to a successful treatment for ovarian cancer is the development of drug resistance to combined chemotherapy. Tumor suppressor genes (TSGs) are wild-type alleles of genes which play regulatory roles in diverse cellular activities, and whose loss of function contributes to the development of cancer. It has been demonstrated that TSGs contribute to drug resistance in several types of solid tumors. However, an overview of the contribution of TSGs to drug resistance in ovarian cancer has not previously been reported. In this study, 15 TSGs responding to drug resistance in ovarian cancer were reviewed to determine the relationship of TSGs with ovarian cancer drug resistance. Furthermore, gene/protein-interaction and bio-association analysis were performed to demonstrate the associations of these TSGs and to mine the potential drug resistance-related genes in ovarian cancer. We observed that the 15 TSGs had close interactions with each other, suggesting that they may contribute to drug resistance in ovarian cancer as a group. Five pathways/processes consisting of DNA damage, apoptosis, cell cycle, DNA binding and methylation may be the key ways with which TSGs participate in the regulation of drug resistance. In addition, ubiquitin C (UBC) and six additional TSGs including the adenomatous polyposis coli gene (APC), death associated protein kinase gene (DAPK), pleiomorphic adenoma gene-like 1 (PLAGL1), retinoblastoma susceptibility gene (RB1), a gene encoding an apoptosis-associated speck-like protein (PYCARD/ASC) and tumor protein 63 (TP63), which had close interactions with the 15 TSGs, are potential drug resistance-related genes in ovarian cancer.

Molecular biology of the primitive neuroectodermal tumor: a review

In terms of its molecular biology and molecular genetics, medulloblastoma is the most thoroughly studied of the pediatric brain tumors. Alterations in chromosome 17, usually an isochromosome 17q, are the most common cytogenetic abnormalities. Similarly, deletion of the short arm of one 17 chromosome, the result of formation of an iso17q, is the most common molecular biological abnormality found. The gene or genes important in the development of medulloblastoma found on chromsome 17 have not yet been identified. Both a tumor suppressor gene and an oncogene have been identified that may play a role in the development of this tumor type. The Patched (PTC) tumor suppressor gene is inactivated in approximately 15% of medulloblatomas; this alteration may be specific to the desmoplastic variant. Oncogenic mutations in the beta-catenin gene are found in a small subset of medulloblastomas. Both of these genes play central roles in developmental pathways. Prognosis in this tumor type has been related to the level of expression of the neurotrophin receptor trkC. In this review, these and other molecular biological and genetic findings are discussed with respect to the development of medulloblastoma.

Interactions of miR-34b/c and TP53 polymorphisms on the risk of intracranial aneurysm

Several lines of evidence indicate that inflammatory processes play a key role in the happening and development of intracranial aneurysm (IA). Recently, polymorphisms in the TP53 gene were shown to be associated with inflammation and inflammatory disease. The aim of this study was to investigate the interactions of miR-34b/c and TP53 Arg72-Pro polymorphisms on the risk of IA in a Chinese population. A total of 590 individuals (including 164 patients with IA and 426 controls) were involved in this study. The polymorphisms (i.e., miR-34b/c rs4938723 and TP53 Arg72-Pro) were genotyped by polymerase chain reaction-restriction fragment length polymorphism assay and DNA sequencing. We found that the CC genotype of miR-34b/c rs4938723 was significantly associated with a decreased risk of IA compared with the TT genotype. Moreover, a significant gene interaction of the carriers with the combined genotypes of miR-34b/c rs4938723CC and TP53 Arg72Pro CG/CC/GG had a decreased risk of IA, compared with those carrying miR-34b/c rs4938723CT/TT+TP53 Arg72Pro GG/CG/CC combined genotypes. These findings suggest that the miR-34b/c rs4938723CC and TP53 Arg72-Pro polymorphisms may be involved in the susceptibility to IA.

TP53 Arg72Pro polymorphism and colorectal cancer risk: a systematic review and meta-analysis

BACKGROUND

The TP53 rs1042522 polymorphism (c.215C>G, Arg72Pro) has been extensively investigated as a potential risk factor for colorectal cancer, but the results have thus far been inconclusive.

METHODS

We searched multiple electronic databases to identify studies investigating the association between the Arg72Pro polymorphism and colorectal cancer. Individual study odds ratios (OR) and their confidence intervals were estimated using allele-frequency, recessive, and dominant genetic models. Summary ORs where estimated using random effects models.

RESULTS

We identified 23 eligible case-control studies, investigating 6,514 cases and 9,334 controls. There was significant between-study heterogeneity for all genetic models. The control group in one of the studies was not in Hardy-Weinberg equilibrium; only three studies reported that genotyping was blinded to case/control status and five studies used tumor tissue for case genotyping. Overall, we did not identify any association between rs1042522 and colorectal cancer risk under an allele-frequency comparison (OR, 0.99; 95% confidence interval, 0.89-1.09). Likewise, no association was evident under dominant or recessive models. Studies using tumor tissue for case genotyping found a protective effect for the Pro allele, compared with studies using somatic DNA (P(interaction) = 0.03). Results were also inconsistent between different genotyping methods (P(interaction) = 0.03).

CONCLUSION

We did not identify an association between TP53 rs1042522 and colorectal cancer. Published results seem to be driven by technical artifacts rather than true biological effects.

IMPACT

Future genetic association studies should use more rigorous genotyping methods and avoid the use of tumor tissue as a source of DNA to prevent genotype misclassification due to loss of heterozygosity.

Chromosome Damage Induced by High-LET α-particles in Plateau-phase C3H 10T1/2 Cells

Chromosome aberrations induced by X-rays and alpha-particles (LET = 177 keV/microns) were observed at the first mitosis in C3H 10T1/2 cells released from density-inhibited cultures. X-radiation induced more chromosome exchanges than breaks (71% vs 27% of total aberrations), while a predominance of breaks (63%) was observed after alpha-irradiation. A linear-quadratic dose-response relationship was obtained for X-rays, while that for alpha-particles was linear. The RBE values for total aberration induction (ranging from 5.1 at low doses to 4.4 at high doses) were very similar to the RBE for cell killing (from 5.2 to 4.3). The RBE for dicentric induction (approximately 2) was much lower than the RBE for the induction of both breaks (from 7 to 6) and interstitial deletions (from 9 to 7). This behaviour supports the hypothesis that chromosome deletions play a major role in the malignant transformation of 10T1/2 cells. A high correlation between cell killing and number of acentric fragments per cell was found. The number of acentrics/cell at the mean lethal dose was about 1.4. This number was reduced to 1.0 when asymmetrical interchanges, which generally result in very small deletions, were subtracted from acentrics. It could be hypothesized that very small deletions could not impair cell survival. However, an alternative hypothesis related to the aneuploid state of C3H 10T1/2 cells can be formulated. Robertsonian translocations were also observed at the first mitosis. The dose-response curve of these translocations appears to be very similar to the dose-response curve for induction of sister chromatid exchanges (observed at the second mitosis) reported by other authors studying the same cell line. This similarity could indicate a general mechanism of action of radiation on the process of recombination of genetic material.

Promoter hypermethylation of the SFRP2 gene is a high-frequent alteration and tumor-specific epigenetic marker in human breast cancer

BACKGROUND

We have previously reported that expression of the Wnt antagonist genes SFRP1 and SFRP5 is frequently silenced by promoter hypermethylation in breast cancer. SFRP2 is a further Wnt inhibitor whose expression was recently found being downregulated in various malignancies. Here we investigated whether SFRP2 is also implicated in human breast cancer, and if so whether SFRP2 promoter methylation might serve as a potential tumor biomarker.

METHODS

We analyzed SFRP2 mRNA expression and SFRP2 promoter methylation in 10 breast cell lines, 199 primary breast carcinomas, 20 matched normal breast tissues and 17 cancer-unrelated normal breast tissues using RT-PCR, realtime PCR, methylation-specific PCR and Pyrosequencing, respectively. SFRP2 protein expression was assessed by immunohistochemistry on a tissue microarray. Proliferation assays after transfection with an SFRP2 expression vector were performed with mammary MCF10A cells. Statistical evaluations were accomplished with SPSS 14.0 software.

RESULTS

Of the cancerous breast cell lines, 7/8 (88%) lacked SFRP2 mRNA expression due to SFRP2 promoter methylation (P < 0.001). SFRP2 expression was substantially restored in most breast cell lines after treatment with 5-aza-2'-deoxycytidine and trichostatin A. In primary breast carcinomas SFRP2 protein expression was strongly reduced in 93 of 125 specimens (74%). SFRP2 promoter methylation was detected in 165/199 primary carcinomas (83%) whereas all cancer-related and unrelated normal breast tissues were not affected by SFRP2 methylation. SFRP2 methylation was not associated with clinicopathological factors or clinical patient outcome. However, loss of SFRP2 protein expression showed a weak association with unfavorable patient overall survival (P = 0.071). Forced expression of SFRP2 in mammary MCF10A cells substantially inhibited proliferation rates (P = 0.045).

CONCLUSION

The SFRP2 gene is a high-frequent target of epigenetic inactivation in human breast cancer. Its methylation leads to abrogation of SFRP2 expression, conferring a growth advantage to epithelial mammary cells. This altogether supports a tumor suppressive function of SFRP2. Although clinical patient outcome was not associated with SFRP2 methylation, the high frequency of this epimutation and its putative specificity to neoplastic cells may qualify SFRP2 promoter methylation as a potential candidate screening marker helping to improve early breast cancer detection.

Phase I study of adenovirus p53 administered by bronchoalveolar lavage in patients with bronchioloalveolar cell lung carcinoma: ECOG 6597

PURPOSE

This pilot phase I trial evaluated the safety and maximum-tolerated dose of p53 gene transfer using an adenovirus vector (Ad-p53) delivered via bronchoalveolar lavage (BAL) to patients with bronchioloalveolar lung carcinoma (BAC).

PATIENTS AND METHODS

Patients were initially administered two treatments of Ad-p53 to a single involved lobe, beginning at 2 x 10(9) viral particles (vp) per dose and escalated to a maximum of 2 x 10(12) vp. If a clinical benefit was seen and the treatment was well tolerated, additional doses could be administered to additional lobes.

RESULTS

Twenty-five patients were treated at doses between 2 x 10(9) and 2 x 10(12) vp. At 2 x 10(12) vp, one patient experienced grade 4 pulmonary toxicity, and one patient died 25 days after his second cycle; therefore, a cohort of 10 patients was treated at the recommended phase II dose of 5 x 10(11) vp, with no grade 4 toxicity observed. The most frequent toxicities included low-grade fever, hypoxia, and dyspnea. Of the 23 assessable patients, 16 had stable disease as their best response. Subjective improvement in breathing was noted in eight patients. Limited distribution of vector was observed, with transient detection in patient sputum for 1 to 2 days after administration.

CONCLUSION

Ad-p53 can be administered safely by BAL at 5 x 10(11) vp with repeated dosing. Stabilization of disease and symptomatic improvement may warrant further studies of Ad-p53 or other adenoviruses administered by BAL in patients with BAC.

[Genetic abnormalities of digestive tract adenocarcinomas and correlation with the histologic sequence of their development]

Over 90% of digestive tract malignancies are adenocarcinomas (ADC) and almost 95% of them have gastric (G), colorectal (CR) or pancreatic (P) localizations. The objectives of this work are to review the genetic abnormalities of ADC in these locations and their potential coincidences, along with the histogenetic correlation of their emergence. Genetic abnormalities affecting over 50% of cases include: in G-ADC, inactivation of suppressor genes of p53, APC and DCC tumor in its intestinal variant, hypoexpression of of caderine E in the diffuse variant and hyperexpression of cyclooxygenase-2 and cyclyn D in the intestinal form; in in CR-ADC, inactivation of of genes p53, APC and DCC together with mutational activation of k-ras oncogen, and in P-ADC, the inactivation of suppressor genes p53, p16 and DPC4 along with mutational activation of k-ras oncogen. P-ADC is the one showing a more characteristic and exclusive genetic mark, followed by CR-ADC. Finally, the histogenetic correlation in the tumorigenic sequence is more evident in CR-ADC, followed by P-ADC. The complex biologic reality of G-ADC makes it more difficult to draw its genetic profile and its histogenetic correlation. In order to understand better the arguments of this work, the authors comment on the genetic-molecular basis governing the life and death of normal somatic cells and the biologic profile of the groups of genes mainly involved in tumorigenesis.

Establishment of a liquid chromatographic/mass spectrometry method for quantification of tetrandrine in rat plasma and its application to pharmacokinetic study

A rapid and sensitive liquid chromatography-tandem mass spectrometric method (LC/MS/MS) for the determination of tetrandrine in rat plasma has been developed, fully validated and successfully applied to pharmacokinetic study in Sprague-Dawley (SD) rats after a single oral administration. Sample preparation involves a liquid-liquid extraction with n-hexane-dichlormethane (65:35, containing 1% 2-propanol isopropyl alcohol, v/v). Tetrandrine and brodimoprim (internal standard) were well separated by LC with a Dikma C(18) column using acetonitrile-methanol-ammonium formate aqueous solution (20mM) containing 0.3% formic acid (20:30:50, v/v/v) as mobile phase. Detection was performed on a triple quadrupole mass spectrometer in multiple reaction monitoring mode. The ionization was optimized using ESI(+) and selectivity was achieved using MS/MS analysis, m/z 623.0-->381.0 and m/z 339.0-->281.0 for tetrandrine and I.S., respectively. The present method exhibited good linearity over the concentration range of 5-2,000 ng/mL for tetrandrine in rat plasma with a lower limit of quantification of 5 ng/mL. The intra- and inter-day precision were 2.0-9.2% and 4.5-9.4%, and the intra- and inter-day accuracy ranged from -7.6 to 10.3% and -6.0 to 5.3%, respectively. No endogenous compounds were found to interfere with the analysis, and tetrandrine was stable during the whole assay period. The method was successfully applied to a pharmacokinetic study after an intragastric administration (i.g.) of tetrandrine to SD rats with a single dose of 50mg/kg. The results confirm that the assay is suitable for the pharmacokinetic study of tetrandrine.

The extracellular matrix protein ITIH5 is a novel prognostic marker in invasive node-negative breast cancer and its aberrant expression is caused by promoter hypermethylation

Inter-alpha-trypsin inhibitors (ITIs) are protease inhibitors stabilizing the extracellular matrix. ITIs consist of one light (bikunin) and two heavy chains (ITIHs). We have recently characterized ITIH5, a novel member of the ITIH gene family, and showed that its messenger RNA is lost in a high proportion of breast tumours. In the present study, an ITIH5-specific polyclonal antibody was generated, validated with western blot and used for immunohistochemical analysis on a tissue microarray; ITIH5 was strongly expressed in epithelial cells of normal breast (n=11/15), while it was lost or strongly reduced in 42% (92/217) of invasive breast cancers. ITIH5 expression in invasive carcinomas was associated with positive expression of oestrogen receptor (P=0.008) and histological grade (P=0.024). Correlation of ITIH5 expression with clinical outcome revealed that patients with primary tumours retaining abundant ITIH5 expression had longer recurrence-free survival (RFS; P=0.037) and overall survival (OS; P=0.044), compared to those with reduced expression (mean RFS: 102 vs 78 months; mean OS: 120 vs 105 months). Methylation-specific PCR analysis frequently showed strong methylation of the ITIH5 promoter in primary breast tumours (41%, n=109) and breast cancer cell lines (n=6). Methylation was significantly associated with mRNA loss (P<0.001; n=39), and ITIH5 expression was induced after treatment of tumour cell lines with the demethylating agent 5-aza-2'-deoxycytidine. Moreover, ITIH5 promoter methylation was significantly associated with reduced OS (P=0.008). The cellular function of ITIH5 was evaluated by forced expression of a full-length ITIH5 complementary DNA in the breast cancer cell line MDA-MB-231, which does not endogenously express ITIH5. ITIH5-expressing clones showed a 40% reduced proliferation rate compared to mock-transfected cells. Overall, these data show that promoter methylation-mediated loss of ITIH5 expression is associated with unfavourable outcome in breast cancer patients, and thus ITIH5 could be used as a prognostic marker, although this marker is not multivariate independent due to its close association with ER expression. Our data indicate that ITIH5 is a candidate class II tumour suppressor gene and could be involved in tumour progression, invasion and metastasis, as its absence is associated with increased proliferation rates and a prognostic value indicating poor clinical outcome.

Genetic relationship among atypical adenomatous hyperplasia, bronchioloalveolar carcinoma and adenocarcinoma of the lung

Atypical adenomatous hyperplasia (AAH) has been recently defined by WHO as a small lesion, not exceeding 5mm in major axis, composed of slightly enlarged alveolar septa lined by pneumocytes with plump, atypical nuclei. AAH is frequently found in tissue surrounding lung adenocarcinoma and is considered a precursor of this subtype of lung cancer by many Authors. However, the genetic relationship between adenocarcinoma and the associated foci of AAH is not well defined. In particular, it is not clear whether multiple foci of AAH and of adenocarcinoma in the same patients are clonally related to each other or represent independent neoplastic foci. To clarify if AAH and the associated cancer are clonally related, we evaluated the genetic distance between these two lesions in 16 patients, using direct sequencing of mitochondrial DNA (D-loop region). Furthermore, LOH analysis for 7 microsatellites (D3S1478 at 3p21, D3S1300 at 3p14.2, D9S942 at 9p21, D5S346 at 5q21, D17S261 at 17p13.1, D18S46 at 18q21, D19S246 at 19q13.2) was also performed. Our results indicate that, in at least 9 out of 13 informative cases (69.2%), AAH and the associated cancer were not clonally related as they showed a different mutation pattern in the mitochondrial D-loop region. These findings were also in agreement with the LOH data which showed losses in different loci in at least three cases. On the contrary an identical LOH pattern between BAC and AAH was found in one case. Similar but not identical LOH pattern between AAH and related tumors was found in other three cases. Therefore, our results suggest that AAH and the associated cancer are genetically independent in agreement with the concept of cancerization field. Less frequently AAH foci could represent an early spread of cells from the main tumor, rather than a precursor lesion.

Age of diagnosis of colorectal cancer in HNPCC patients is more complex than that predicted by R72P polymorphism in TP53

Hereditary nonpolyposis colorectal cancer (HNPCC) is an autosomal dominantly inherited cancer syndrome associated with germline mutations in DNA mismatch repair (MMR) genes. Recently a polymorphism at codon 72 (R72P) in the tumour suppressor gene TP53 has been implicated in the age of disease onset in HNPCC. In this report we have studied a large cohort of HNPCC patients to assess the impact of this polymorphism on disease expression and age of diagnosis of colorectal cancer (CRC). DNA samples from 218 HNPCC mutation positive patients from Australia and Poland were genotyped for the arginine to proline change at codon 72 in the TP53 gene. The association between the polymorphism and disease characteristics (mutation status, disease expression and age of diagnosis of CRC) was tested using Pearson's Chi-square and Kaplan-Meier survival analysis. Our study of Australian and Polish HNPCC patients does not provide evidence for an association between the Arg/Pro (GC) genotype of the R72P polymorphism and age of diagnosis of CRC. The R72P polymorphism was examined in HNPCC patients and found to be not associated with disease development in either the Australian or Polish populations. When gene mutation status (hMLH1 or hMSH2) was included in the analysis some evidence of an affect was observed. The genotyping revealed in the Australian population that the R72P polymorphism was under-represented in the hMSH2 group whereas it was over-represented in the Polish hMSH2 group. A similar trend was observed for hMLH1 in both groups but was not significant. Age of diagnosis of CRC in HNPCC patients is therefore more complex than that predicted by the R72P TP53 polymorphism alone, suggesting an inter-relationship with other genetic and/or environmental factors.

Cytokeratin expression in oral submucous fibrosis--an immunohistochemical study

BACKGROUND

Oral submucous fibrosis (OSF) is a pre-malignant condition caused by habitual use of areca nut, affecting the oro-pharynx and characterized by progressive fibrosis. Alteration of cytokeratin (CK) expression has been documented in leukoplakia and oral cancer (OC). However, very little is known of CK alterations in OSF. The present study was carried out to characterize the CK profile in OSF and ascertain if this could be used as a surrogate marker for malignant transformation.

METHODS

Paraffin-embedded tissues of OSF (n = 50), normal (n = 10) and OC (n = 10) were stained with pancytokeratin (PanCK), high molecular weight cytokeratin (HMWCK), CKs 18, 14, 8, 5, 4 and 1 by immunohistochemistry.

RESULTS

Significant difference in the CK staining pattern was seen between normal, OSF and cancer. Significant changes in OSF included increased intensity of staining for PanCK and HMWCK, aberrant expression of CK8 and decreased expression of CKs 5 and 14.

CONCLUSION

Cytokeratin profile of OSF was significantly different from normals for PanCK, HMWCK, CK8, 5 and 14 suggesting their potential to be used as surrogate markers of malignant transformation. Further studies will help in better defining the nature and clinical implications of these alterations.

Multiple mechanisms underlie the aberrant expression of the human kallikrein 6 gene in breast cancer

Human kallikrein 6 (KLK6) was identified based on its transient upregulation in a primary breast tumor and its subsequent silencing in a metastatic tumor from the same patient. The molecular mechanism(s) underlying the deregulated expression of KLK6 during cancer progression are currently unknown. Here, we provide evidence that aberrant expression of KLK6 is regulated at the level of transcription by multiple cooperating mechanisms. KLK6 can be reactivated in non-expressing breast cancer cells by treatment with 5-aza-2'-deoxycytidine (5-aza-dC), a compound causing DNA demethylation. Trichostatin A (TSA), an inhibitor of histone deacetylases, resulted in moderate induction of KLK6 only in MDA-MB-231 cells. However, combined 5-aza-dC/TSA treatment resulted in synergistic activation of KLK6. We show that KLK6 inactivation is associated with hypermethylation of specific CpG dinucleotides located in the KLK6 proximal promoter and overexpression with complete demethylation. These results indicate a causal role of DNA methylation and chromatin structure in cancer-associated loss of KLK6 expression. In some breast cancer cell lines, KLK6 expression could be restored by the vitamin D3 analog EB1089. Our data indicate that transcriptional deregulation of KLK6 in cancer cells during breast cancer progression is complex and certainly not uniform in different tumors, involving epigenetic mechanisms as well as pathways regulated by nuclear receptors. This allows for the pharmacological modulation of KLK6 with potential therapeutic implications.

Downregulation of human kallikrein 10 (KLK10/NES1) by CpG island hypermethylation in breast, ovarian and prostate cancers

OBJECTIVE

The human kallikrein 10 (KLK10)/normal epithelial cell-specific-1 (NES1) gene is highly expressed in normal mammary, ovary and prostate cells, but its expression is dramatically decreased in cancer cell lines. Recently, it has been shown that CpG island hypermethylation of the KLK10 gene is responsible for the tumor-specific loss of KLK10 gene expression in certain breast cancer cell lines.

METHOD

We examined the role of CpG island hypermethylation in the tumor-specific loss of KLK10 expression in breast, ovarian and prostate cancers. We treated cells with the demethylating agent 5-aza-2'-deoxycytidine (dC) and monitored changes in KLK10 mRNA by RT-PCR and secreted hK10 protein expression by ELISA. The following cell lines were used: MDA-MB-231, MDA-MB-468, MCF-7, ZR-75-1, T-47D and BT-474 (breast); BG-1, MDAH-2774, HTB-75, HTB-161, PA-1 and ES-2 (ovary), and LNCaP and PC-3 (prostate).

RESULTS

Upregulation of KLK10 mRNA levels, which was accompanied by an increase in secreted hK10 protein concentration, was observed for a subset of breast, ovarian, and prostate tumor cell lines after 5-aza-2'-dC. Genomic sequencing of sodium-bisulfite-treated DNA demonstrated that CpG sites within the KLK10 gene exon 3 were highly methylated. Hypermethylation of exon 3 CpG regions was also detected in primary ovarian cancers.

CONCLUSION

These data suggest that CpG island hypermethylation plays an important role in the downregulation of kallikrein 10 mRNA and protein expression, but it cannot explain the pattern of expression of this gene in all cell lines or tissue tested.

Isolation of mesenchymal stem cells from cryopreserved human umbilical cord blood

Umbilical cord blood (UCB) is well known to be a rich source of hematopoietic stem cells with practical and ethical advantages. Because mesenchymal stem cells (MSCs) from bone marrow have been regarded as good materials for cell/gene therapy as well as for tissue engineering because of their multidifferentiation potential, a number of trials have been undertaken to isolate MSCs from UCB. However, the results have been controversial, and little has become known about the effect of cryopreservation on the isolation of these stem cells. In this study, we examined the ability of cryopreserved UCB-derived cells to produce MSCs. Various culture conditions, including the seeding concentrations of cells and the media used, were investigated. We were able to obtain adherent cell populations after 3 to 5 weeks in our culture conditions from UCB-derived mononuclear cell fractions that had undergone cryopreservation for 0.1 to 5 years. These cells exhibited a fibroblast-like morphology and typical mesenchymal-like immunophenotypes. The results indicate that cryopreserved human UCB fractions can be used as an alternative source of MSCs for experimental and clinical applications as well as for tissue engineering.

Current strategies in cancer gene therapy

Cancer gene therapy is the most studied application of gene therapy. Many genetic alterations are involved in the transformation of a normal cell into a neoplastic one. The two main gene groups involved in cancer development are oncogenes and tumor suppressor genes. While the latter eliminates cancerous cells via apoptosis, the former enhances cell proliferation. Therefore, apoptotic genes and anti-oncogenes are widely used in cancer gene therapy. In addition to oncogenes and tumor suppressor genes, chemotherapy and gene therapy can be combined through suicide gene strategy. A suicide gene encodes for a non-mammalian enzyme; this enzyme is used to convert a non-toxic prodrug into its active cytotoxic metabolite within the cancerous cells. Tumor suppressor genes, anti-oncogenes and suicide genes target cancer cells on the molecular level. On the other hand, cancer is immunogenic in nature; therefore, it can also be targeted on the immunological level. Boosting the immune response against cancerous cells is usually achieved via genes encoding for cytokines. Interleukin-12 gene, for example, is one of the most studied cytokine genes for cancer gene therapy applications. DNA vaccines are also used after conventional treatments to eliminate remnant malignant cells. All these therapeutic strategies and other strategies namely anti-angiogenesis and drug resistant genes are briefly reviewed and highlighted in this article.

Gene therapy in clinical medicine

Although the field of gene therapy has experienced significant setbacks and limited success, it is one of the most promising and active research fields in medicine. Interest in this therapeutic modality is based on the potential for treatment and cure of some of the most malignant and devastating diseases affecting humans. Over the next decade, the relevance of gene therapy to medical practices will increase and it will become important for physicians to understand the basic principles and strategies that underlie the therapeutic intervention. This report reviews the history, basic strategies, tools, and several current clinical paradigms for application.

Gene therapy in heart and lung disease

PURPOSE OF REVIEW

Gene therapy utilizes viral and non-viral vectors to transfer genetic material into a host in the hope of treating disease. This article will review the potential applications of gene therapy in the treatment of cardiac and pulmonary diseases.

RECENT FINDINGS

The results from several phase I and II clinical trials have recently been published. In patients with ischemic heart disease, evidence of coronary revascularization has been observed after the delivery of angiogenic factors. Several trials have demonstrated a reduction in anginal symptoms, increases in exercise tolerance, and objective improvements in myocardial perfusion. Evidence of the transfer of therapeutic genes has been observed in human trials of inherited pulmonary diseases. Unfortunately, there has been little evidence of clinical efficacy in these studies. A variety of gene therapy strategies are being explored in the treatment of thoracic malignancies. Partial antitumor responses have occurred in some of the subjects enrolled in these studies.

SUMMARY

Significant progress has been made in the field of gene therapy in the past decade. Data from these early animal and human clinical trials will provide important information to guide future studies.

Intraepidermal cells of paget’s carcinoma of the breast can be genetically different from those of the underlying carcinoma

Paget's carcinoma (PC) of the breast is characterized by neoplastic cells of "glandular" type located within the epidermis of the nipple-areolar complex, often associated with an underlying ductal carcinoma, either in situ or invasive. At present the origin of PC cells is controversial, although there is a widespread opinion that PC cells are "foreign" elements to the epidermis resulting from an epidermotropic migration of neoplastic elements from an underlying ductal carcinoma. An alternative view is that some cases result from neoplastic transformation of preexisting, innocent intraepidermal clear cells of the nipple-areolar complex (Toker cells) that migrate from nonneoplastic ducts. Consequently, 10 cases were studied using methods for clonality (ie, loss of heterozygosity and mitochondrial DNA displacement loop sequence analysis). Microdissection of intraepidermal neoplastic cells and of cells from underlying duct carcinomas and metastases was performed. In no fewer than 2 cases, PC cells were genetically different from underlying lesions, which showed consistent homology among themselves. Therefore, it is suggested that the rule of epidermotropism by neoplastic cells from an underlying carcinoma is not applicable to all cases, and that in some cases PC cells might be the result of neoplastic transformation of preexisting intraepidermal nonneoplastic cells. Consequently, the underlying tumors are coincidental neoplastic lesions (collision tumors).

Demonstration of cytokeratin-5 non-expression in tobacco related oral carcinogenesis—use of reverse transcriptase polymerase chain reaction as a sensitive assay

Cytokeratins (CK) are the epithelia specific intermediate filament proteins. We have shown consistent non-expression of CK-5 protein in human oral pre-cancer and cancer, in earlier studies. To investigate whether non-expression of CK-5 protein is the result of transcriptional or translational block and to evaluate the possibility if CK-5 non-expression can be used as a marker for early diagnosis of tobacco related oral cancer, RT-PCR using CK-5 specific primers was conducted. Out of 36 precancerous lesions and 29 squamous cell carcinomas (SCC) of buccal mucosa (BM) samples studied, 11 and 13 samples respectively of precancer and SCC did not show CK-5 product in RT-PCR. Down regulation of CK-5 mRNA expression was also observed in some samples. Thus, in conclusion, our results have shown that CK-5 non-expression is the result of transcriptional block. We proposed CK-5 non-expression as a potential marker for the early diagnosis of tobacco related oral cancer.

Immortalization of normal human embryonic fibroblasts by introduction of either the human papillomavirus type 16 E6 or E7 gene alone

The ability of the human papillomavirus type 16 (HPV-16) E6 or E7 gene to induce immortalization of normal human embryonic fibroblast WHE-7 cells was examined. WHE-7 cells at 9 population doublings (PD) were infected with retrovirus vectors encoding either HPV-16 E6 or E7 alone or both E6 and E7 (E6/E7). One of 4 isolated clones carrying E6 alone became immortal and is currently at >445 PD. Four of 4 isolated clones carrying E7 alone escaped from crisis and are currently at >330 PD. Three of 5 isolated clones carrying E6/E7 were also immortalized and are currently at >268 PD. The immortal clone carrying E6 only and 2 of the 3 immortal clones carrying E6/E7 expressed a high level of E6 protein, and all the immortal clones carrying E7 alone and the other immortal clone carrying E6/E7 expressed a high level of E7 protein when compared to their mortal or precrisis clones. The immortal clones expressing a high level of E6 or E7 protein were positive for telomerase activity or an alternative mechanism of telomere maintenance, respectively, known as ALT (alternative lengthening of telomeres). All the mortal or precrisis clones were negative for both phenotypes. All the immortal clones exhibited abrogation of G1 arrest after DNA damage by X-ray irradiation. The expression of INK4a protein (p16(INK4a)) was undetectable in the E6-infected mortal and immortal clones, whereas Rb protein (pRb) was hyperphosphorylated only in the immortal clone. The p16(INK4a) protein was overexpressed in all the E7-infected immortal clones and their clones in the pre-crisis period as well as all the E6/E7-infected mortal and immortal clones, but the pRb expression was downregulated in all of these clones. These results demonstrate for the first time to our knowledge that HPV-16 E6 or E7 alone can induce immortalization of normal human embryonic fibroblasts. Inactivation of p16(INK4a)/pRb pathways in combination with activation of a telomere maintenance mechanism is suggested to be necessary for immortalization of normal human embryonic fibroblasts by these viral oncogenes. The susceptibility of human cells to immortalization may be related to the state of differentiation of the cells.

Thrombospondin-1 induces matrix metalloproteinase-2 activation in vascular smooth muscle cells

INTRODUCTION

Thrombospondin-1 (TSP-1), an extracellular matrix (ECM) glycoprotein, is associated with a variety of cellular processes relevant to atherosclerosis and intimal hyperplasia, including vascular smooth muscle cell (VSMC) migration. Matrix metalloproteinase-2 (MMP2) is associated with basement membrane and ECM degradation, important processes for cell migration. We hypothesized that TSP-1 modulates MMP2 activity in VSMCs and is critical for VSMC migration.

METHODS

Quiescent bovine aortic VSMCs (48 hours) were incubated in serum-free media (SFM) with or without TSP-1 (10 or 20 microg/mL). Gelatinase activity was measured with zymography to determine pro-MMP2 and MMP2 activity. MMP2 messenger RNA expression was determined with Northern blot analysis. Invasion assays were performed. A binding assay was used to determine the specificity of TSP-1 binding to MMP2. Blots were quantified with densitometry, and all comparisons were made with a paired t test.

RESULTS

TSP-1 induced production of activated forms of MMP2, as well as upregulation of pro-MMP2. MMP2 mRNA was upregulated 1.7-fold by TSP-1 at 10 and 20 microg/mL. GM6001, an MMP inhibitor, inhibited VSMC migration across the matrix barrier, whereas migration that occurred in the absence of the matrix barrier was unaffected. With a binding assay, TSP-1 interacted physically with MMP2, and TSP-1-bound MMP2 showed the strongest binding activity in comparison with collagen I, fibronectin, and elastin.

CONCLUSION

TSP-1 induced MMP2 activation through transcriptional and posttranslational mechanisms. These findings imply that MMP2 activation is relevant to the mechanism of TSP-1-induced VSMC migration.

Simultaneous acceleration of the cell cycle and suppression of apoptosis by splice variant delta-6 of the candidate tumour suppressor LUCA-15/RBM5

BACKGROUND

The short arm of chromosome 3 is thought to include one or more tumour suppressor genes (TSGs), since carcinoma of various tissues display deletions in this region. Many genes mapping to this region have recently been identified, including the LUCA-15/RBM5 gene.

RESULTS

In this study we report the cloning from human bone marrow library of a splice variant of LUCA-15 which lacks exon 6, resulting in a frameshift and producing a truncated protein of 150 amino acids instead of 815 amino acids. This variant is widely expressed at a low level in normal tissues and is expressed at increased levels in T-leukaemic cell lines. Over-expression of this splice variant after electroporation both shortened the cell cycle and inhibited CD95-mediated apoptosis in CEM-C7 T-cells. In marked contrast, over-expression of the full length LUCA-15/RBM5 suppressed cell proliferation both by inducing apoptosis and by extending the G1 phase of the cell cycle.

CONCLUSION

These results, taken together with previous observations from ourselves and others, suggest that LUCA-15 is involved in the control of both apoptosis and the cell cycle. Since oncogenesis often relies on separate changes in molecules regulating apoptosis on the one hand, and proliferation, on the other, the discovery of a candidate tumour suppressor gene which affects both processes simultaneously is likely to be of major significance.

Molecular biology and genetics of breast cancer development: a clinical perspective

Understanding the molecular and genetic events affecting breast cancer development not only helps oncologists address important questions commonly asked by their patients but also helps clinicians gain insights into the biology of the disease. Although the molecular and genetic determinants of most sporadic breast cancer remain unknown, significant advances in the understanding of events that contribute to breast cancer formation have been made. It is now recognized that mutations in some tumor suppressor genes, such as p53, BRCA1, BRCA2, PTEN, or ATM, or epigenetic functional inactivation of other tumor suppressor genes, such as SYK and NES1, appear to play important early roles in the formation of some breast cancers. In addition, alterations in proto-oncogenes, such as HER2/neu, may contribute to the development of some breast cancer. The goal of this article is to further introduce clinicians to molecular and genetic pathways that contribute to breast cancer formation. By participating in the study of breast cancer development at the molecular as well as the histopathological level, oncologists can help develop novel prevention, diagnostic, and therapeutic approaches for the future.