Fully automatic brain extraction algorithm for axial T2-weighted magnetic resonance images

In this paper we propose two brain extraction algorithms (BEA) for T2-weighted magnetic resonance imaging (MRI) scans. The T2-weighted image is first filtered with a low pass filter (LPF) to remove or subdue the background noise. Then the image is diffused to enhance the brain boundaries. Using Ridler's method a threshold value for intensity is obtained. Using the threshold value a rough binary brain image is obtained. By performing morphological operations and using the largest connected component (LCC) analysis, a brain mask is obtained from which the brain is extracted. This method uses only 2D information of slices and is named as 2D-BEA. The concept of LCC failed in few slices. To overcome this problem, 3D information available in adjacent slices is used which resulted in 3D-BEA. Experimental results on 20 MRI data sets show that the proposed 3D-BEA gave excellent results. The performance of this 3D-BEA is better than 2D-BEA and other popular methods, brain extraction tool (BET) and brain surface extractor (BSE).

Glioblastoma-specific protein interaction network identifies PP1A and CSK21 as connecting molecules between cell cycle-associated genes

Glioblastoma (GBM; grade IV astrocytoma) is a very aggressive form of brain cancer with a poor survival and few qualified predictive markers. This study integrates experimentally validated genes that showed specific upregulation in GBM along with their protein-protein interaction information. A system level analysis was used to construct GBM-specific network. Computation of topological parameters of networks showed scale-free pattern and hierarchical organization. From the large network involving 1,447 proteins, we synthesized subnetworks and annotated them with highly enriched biological processes. A careful dissection of the functional modules, important nodes, and their connections identified two novel intermediary molecules CSK21 and protein phosphatase 1 alpha (PP1A) connecting the two subnetworks CDC2-PTEN-TOP2A-CAV1-P53 and CDC2-CAV1-RB-P53-PTEN, respectively. Real-time quantitative reverse transcription-PCR analysis revealed CSK21 to be moderately upregulated and PP1A to be overexpressed by 20-fold in GBM tumor samples. Immunohistochemical staining revealed nuclear expression of PP1A only in GBM samples. Thus, CSK21 and PP1A, whose functions are intimately associated with cell cycle regulation, might play key role in gliomagenesis.

ErbB-2 expression and its association with other biological parameters of breast cancer among Indian women

OBJECTIVES

Overexpression of the epidermal growth factor receptor family genes, which include ErbB-1, 2, 3 and 4, has been implicated in a number of cancers. We have studied the extent of ErbB-2 overexpression among Indian women with sporadic breast cancer.

METHODS

Immunohistochemistry and genomic polymerase chain reaction (PCR) were used to study the ErbB2 overexpression. ErbB2 status was correlated with other clinico-pathological parameters, including patient survival.

RESULTS

ErbB-2 overexpression was detected in 43.2% (159/368) of the cases by immunohistochemistry. For a sub-set of patients (n = 55) for whom total DNA was available, ErbB-2 gene amplification was detected in 25.5% (14/55) of the cases by genomic PCR. While the ErbB2 overexpression was significantly higher in patients with lymphnode (chi2 = 12.06, P < or = 0.001), larger tumor size (chi2 = 8.22, P = 0.042) and ductal carcinoma (chi2 = 15.42, P < or = 0.001), it was lower in patients with disease-free survival (chi2 = 22.13, P < or = 0.001). Survival analysis on a sub-set of patients for whom survival data were available (n = 179) revealed that ErbB-2 status (chi2 =25.94, P < or = 0.001), lymphnode status (chi2 = 12.68, P < or = 0.001), distant metastasis (chi2 = 19.49, P < or = 0.001) and stage of the disease (chi2 = 28.04, P < or = 0.001) were markers of poor prognosis.

CONCLUSIONS

ErbB-2 overexpression was significantly greater compared with the Western literature, but comparable to other Indian studies. Significant correlation was found between ErbB-2 status and lymphnode status, tumor size and ductal carcinoma. ErbB-2 status, lymph node status, distant metastasis and stage of the disease were found to be prognostic indicators.

HDAC inhibitor valproic acid enhances tumor cell kill in adenovirus-HSVtk mediated suicide gene therapy in HNSCC xenograft mouse model

Safety, efficacy and enhanced transgene expression are the primary concerns while using any vector for gene therapy. One of the widely used vectors in clinical trials is adenovirus which provides a safe way to deliver the therapeutic gene. However, adenovirus has poor transduction efficiency in vivo since most tumor cells express low coxsackie and adenovirus receptors. Similarly transgene expression remains low, possibly because of the chromatization of adenoviral genome upon infection in eukaryotic cells, an effect mediated by histone deacetylases (HDACs). Using a recombinant adenovirus (Ad-HSVtk) carrying the herpes simplex thymidine kinase (HSVtk) and GFP genes we demonstrate that HDAC inhibitor valproic acid can bring about an increase in CAR expression on host cells and thereby enhanced Ad-HSVtk infectivity. It also resulted in an increase in transgene (HSVtk and GFP) expression. This, in turn, resulted in increased cell kill of HNSCC cells, following ganciclovir treatment in vitro as well as in vivo in a xenograft nude mouse model.

BRCA1 and BRCA2 germline mutation analysis among Indian women from south India: identification of four novel mutations and high-frequency occurrence of 185delAG mutation

Mutations in the BRCA1 and BRCA2 genes profoundly increase the risk of developing breast and/or ovarian cancer among women. To explore the contribution of BRCA1 and BRCA2 mutations in the development of hereditary breast cancer among Indian women, we carried out mutation analysis of the BRCA1 and BRCA2 genes in 61 breast or ovarian cancer patients from south India with a positive family history of breast and/or ovarian cancer. Mutation analysis was carried out using conformation-sensitive gel electrophoresis (CSGE) followed by sequencing. Mutations were identified in 17 patients (28.0%); 15 (24.6%) had BRCA1 mutations and two (3.28%) had BRCA2 mutations. While no specific association between BRCA1 or BRCA2 mutations with cancer type was seen, mutations were more often seen in families with ovarian cancer. While 40% (4/10) and 30.8% (4/12) of families with ovarian or breast and ovarian cancer had mutations, only 23.1% (9/39) of families with breast cancer carried mutations in the BRCA1 and BRCA2 genes. In addition, while BRCA1 mutations were found in all age groups, BRCA2 mutations were found only in the age group of < or =40 years. Of the BRCA1 mutations, there were three novel mutations (295delCA; 4213T-->A; 5267T-->G) and three mutations that have been reported earlier. Interestingly, 185delAG, a BRCA1 mutation which occurs at a very high frequency in Ashkenazi Jews, was found at a frequency of 16.4% (10/61). There was one novel mutation (4866insT) and one reported mutation in BRCA2. Thus, our study emphasizes the importance of mutation screening in familial breast and/or ovarian cancers, and the potential implications of these findings in genetic counselling and preventive therapy.

Serum proteomics of glioma: methods and applications

The prognosis of patients with glioblastoma, the most malignant adult glial brain tumor, remains poor in spite of advances in treatment procedures, including surgical resection, irradiation and chemotherapy. Genetic heterogeneity of glioblastoma warrants extensive studies in order to gain a thorough understanding of the biology of this tumor. While there have been several studies of global transcript profiling of glioma with the identification of gene signatures for diagnosis and disease management, translation into clinics is yet to happen. Serum biomarkers have the potential to revolutionize the process of cancer diagnosis, grading, prognostication and treatment response monitoring. Besides having the advantage that serum can be obtained through a less invasive procedure, it contains molecules at an extraordinary dynamic range of ten orders of magnitude in terms of their concentrations. While the conventional methods, such as 2DE, have been in use for many years, the ability to identify the proteins through mass spectrometry techniques such as MALDI-TOF led to an explosion of interest in proteomics. Relatively new high-throughput proteomics methods such as SELDI-TOF and protein microarrays are expected to hasten the process of serum biomarker discovery. This review will highlight the recent advances in the proteomics platform in discovering serum biomarkers and the current status of glioma serum markers. We aim to provide the principles and potential of the latest proteomic approaches and their applications in the biomarker discovery process. Besides providing a comprehensive list of available serum biomarkers of glioma, we will also propose how these markers will revolutionize the clinical management of glioma patients.

Cytotoxicity of half sandwich ruthenium(II) complexes with strong hydrogen bond acceptor ligands and their mechanism of action

Neutral and cationic organometallic ruthenium(II) piano stool complexes of the type [(eta(6)-cymene)RuCl(X)(Y)] (complexes R1-R8) has been synthesized and characterized. In cationic complexes, X, Y is either a eta(2) phosphorus ligand such as 1,1-bis(diphenylphosphino)methane (DPPM) and 1,2-bis(diphenylphosphino)ethane (DPPE) or partially oxidized ligands such as 1,2-bis(diphenylphosphino)methane monooxide (DPPMO) and 1,2-bis(diphenylphosphino)ethane monooxide (DPPEO) which are strong hydrogen bond acceptors. In neutral complexes, X is chloride and Y is a monodentate phosphorous donor. Complexes with DPPM and DPPMO ligands ([(eta(6)-cymene)Ru(eta(2)-DPPM)Cl]PF(6) (R2), [(eta(6)-cymene)Ru(eta(2)-DPPMO)Cl]PF(6) (R3), [(eta(6)-cymene)Ru(eta(1)-DPPM)Cl(2)] (R5) and [(eta(6)-cymene)Ru(eta(1)-DPPMO)Cl(2)] (R6) show good cytotoxicity. Growth inhibition study of several human cancer cell lines by these complexes has been carried out. Mechanistic studies for R5 and R6 show that inhibition of cancer cell growth involves both cell cycle arrest and apoptosis induction. Using an apoptosis PCR array, we identified the sets of anti-apoptotic genes that were down regulated and pro-apoptotic genes that were up regulated. These complexes were also found to be potent metastasis inhibitors as they prevented cell invasion through matrigel. The complexes were shown to bind DNA in a non intercalative fashion and cause unwinding of plasmid DNA in cell-free medium by competitive ethidium bromide binding, viscosity measurements, thermal denaturation and gel mobility shift assays.

Novel glioblastoma markers with diagnostic and prognostic value identified through transcriptome analysis

PURPOSE

Current methods of classification of astrocytoma based on histopathologic methods are often subjective and less accurate. Although patients with glioblastoma have grave prognosis, significant variability in patient outcome is observed. Therefore, the aim of this study was to identify glioblastoma diagnostic and prognostic markers through microarray analysis.

EXPERIMENTAL DESIGN

We carried out transcriptome analysis of 25 diffusely infiltrating astrocytoma samples [WHO grade II--diffuse astrocytoma, grade III--anaplastic astrocytoma, and grade IV--glioblastoma (GBM)] using cDNA microarrays containing 18,981 genes. Several of the markers identified were also validated by real-time reverse transcription quantitative PCR and immunohistochemical analysis on an independent set of tumor samples (n = 100). Survival analysis was carried out for two markers on another independent set of retrospective cases (n = 51).

RESULTS

We identified several differentially regulated grade-specific genes. Independent validation by real-time reverse transcription quantitative PCR analysis found growth arrest and DNA-damage-inducible alpha (GADD45alpha) and follistatin-like 1 (FSTL1) to be up-regulated in most GBMs (both primary and secondary), whereas superoxide dismutase 2 and adipocyte enhancer binding protein 1 were up-regulated in the majority of primary GBM. Further, identification of the grade-specific expression of GADD45alpha and FSTL1 by immunohistochemical staining reinforced our findings. Analysis of retrospective GBM cases with known survival data revealed that cytoplasmic overexpression of GADD45alpha conferred better survival while the coexpression of FSTL1 with p53 was associated with poor survival.

CONCLUSIONS

Our study reveals that GADD45alpha and FSTLI are GBM-specific whereas superoxide dismutase 2 and adipocyte enhancer binding protein 1 are primary GBM-specific diagnostic markers. Whereas GADD45alpha overexpression confers a favorable prognosis, FSTL1 overexpression is a hallmark of poor prognosis in GBM patients.

Mixed ligand ruthenium(II) complexes of bis(pyrid-2-yl)-/bis(benzimidazol-2-yl)-dithioether and diimines: study of non-covalent DNA binding and cytotoxicity

A series of mixed ligand ruthenium(II) complexes [Ru(pdto)(diimine)](ClO4)2/(PF6)2 1-3 and [Ru(bbdo)(diimine)](ClO4), 4-6, where pdto is 1,8-bis(pyrid-2-yl)-3,6-dithiooctane, bbdo is 1,8-bis(benzimidazol-2-yl)-3,6-dithiooctane and diimine is 1,10-phenanthroline (phen), dipyrido-[3,2-d:2',3'-f]-quinoxaline (dpq) and dipyrido[3,2-a:2',3'-c]phenazine (dppz), have been isolated and characterised by analytical and spectral methods. The complexes [Ru(pdto)(phen)](PF6)2 la, [Ru(pdto)(dpq)(Cl](PF6) 2a, [Ru(bbdo)(phen)](PF6)2 4a and [Ru(bbdo)(dpq)](ClO4)2 5 have been structurally characterized and their coordination geometries around ruthenium(II) are described as distorted octahedral. In la, 4a and 5 the two thioether sulfur and two py/bzim nitrogen atoms of the tetradentate pdto/bbdo ligand are folded around Ru(II) to give predominantly a "cis-alpha" configuration. (I)H NMR spectral data of the complexes support this configuration in solution. In [Ru(pdto)(dpq)Cl](PF6) 2a with a distorted octahedral coordination geometry, one of the two py nitrogens of pdto is not coordinated. The DNA binding constants (Kb: 2, 2.00 +/- 0.02 x 10(4) M(-1), s = 1.0; 3, 3.00 +/- 0.01 x 10(6) M(-1), s = 1.3) determined by absorption spectral titrations of the complexes with CT DNA reveal that 3 interacts with DNA more tightly than 2 through partial intercalation of the extended planar ring of coordinated dppz with the DNA base stack. The DNA binding affinities of the complexes increase with increase in the number of planar aromatic rings in the co-ligand, and on replacing both the py moieties in pdto complexes (1-3) by bzim moieties to give bbdo complexes (4-6). Upon interaction with CT DNA the complexes 1, 2, 5 and 6 show a decrease in anodic current in the cyclic voltammograms. On the other hand, interestingly, 3 and 4 show an increase in anodic current suggesting their involvement in electrocatalytic guanine oxidation. Interestingly, of all the complexes, only 6 alters the superhelicity of DNA upon binding with supercoiled pBR322 DNA. The cytotoxicities of the dppz complexes 3 and 6, which avidly bind to DNA, have been examined by screening them against cell lines of different cancer origins. It is noteworthy that 6 exhibits selectivity with higher cytotoxicity against the melanoma cancer cell line (A375) than other cell lines, potency approximately twice that of cisplatin and toxicity to normal cells 3 and 90 times less than cisplatin and adriamycin respectively.

Shift in AP-2alpha localization characterizes astrocytoma progression

Activator protein 2alpha (AP-2alpha) has been shown to be lost in the advanced stages of many cancers, including gliomas. In this study, we wanted to analyze the expression of AP-2alpha in astrocytoma samples of different grades both at the RNA level, by real-time qPCR and at the protein level, by immunohistochemistry, and to examine its correlation, if any, with patient outcome. Five Grade I, 14 Grade II, 18 Grade III, 72 Grade IV samples and 13 normal brain controls were included. We did not find any clear pattern of regulation at the RNA level with tumor grade. The RNA expression levels however, correlated to a large extent with the nuclear AP-2alpha staining in these samples (72.09%; 31/43). Further, we did not find a complete loss of nuclear AP-2alpha expression in the higher grades, in contrast to previous reports. Interestingly, we found cytoplasmic AP-2alpha expression in a majority of higher grade astrocytomas (Grade IV-85%; 33/39 and Grade III-74%; 14/19) in comparison to lower grades (Grade I-0%; 0/5 and Grade II-37.5%; 3/8) suggesting that the translocation of this protein from the nucleus to the cytoplasm may be responsible for the increased malignancy. The nuclear expression in these grades was found to be concomitantly reduced. Within GBMs, we found that decreased nuclear expression was indicative of a better prognosis. The striking observation was the shift in localization of this protein from the nucleus to the cytoplasm with increasing tumor grade, pointing to a crucial role for this transcription factor in the progression of astrocytomas.

Survival signaling by Notch1: mammalian target of rapamycin (mTOR)-dependent inhibition of p53

Notch signaling is believed to promote cell survival in general. However, the mechanism is not clearly understood. Here, we show that cells expressing intracellular domain of human Notch1 (NIC-1) are chemoresistant in a wild-type p53-dependent manner. NIC-1 inhibited p53 by inhibiting its activating phosphorylations at Ser(15), Ser(20), and Ser(392) as well as nuclear localization. In addition, we found that inhibition of p53 by NIC-1 mainly occurs through mammalian target of rapamycin (mTOR) using phosphatidylinositol 3-kinase (PI3K)-Akt/protein kinase B (PKB) pathway as the mTOR inhibitor, rapamycin treatment abrogated NIC-1 inhibition of p53 and reversed the chemoresistance. Consistent with this, rapamycin failed to reverse NIC-1-induced chemoresistance in cells expressing rapamycin-resistant mTOR. Further, ectopic expression of eukaryotic initiation factor 4E (eIF4E), a translational regulator that acts downstream of mTOR, inhibited p53-induced apoptosis and conferred protection against p53-mediated cytotoxicity to similar extent as that of NIC-1 overexpression but was not reversed by rapamycin, which indicates that eIF4E is the major target of mTOR in Notch1-mediated survival signaling. Finally, we show that MCF7 (breast cancer) and MOLT4 (T-cell acute lymphoblastic leukemia) cells having aberrant Notch1 signaling are chemoresistant, which can be reversed by both PI3K and mTOR inhibitors. These results establish that Notch1 signaling confers chemoresistance by inhibiting p53 pathway through mTOR-dependent PI3K-Akt/PKB pathway and imply that p53 status perhaps is an important determinant in combination therapeutic strategies, which use mTOR inhibitors and chemotherapy.

Apoptosis induction by activator protein 2alpha involves transcriptional repression of Bcl-2

Activator protein 2alpha (AP-2alpha) induces cytotoxicity by inducing cell cycle arrest and apoptosis. In this study we investigated the mechanism of apoptosis induction by AP-2alpha. We found that AP-2alpha induced apoptosis efficiently in cells treated with benzyloxycar-bonyl-IETD-fluoromethyl ketone or FADD-silenced cells but failed to do so in benzyloxycarbonyl-LEHD-fluoromethyl ketone-treated or apoptosis protease activation factor-1 (Apaf1)-silenced cells, suggesting the central role of mitochondria in AP-2alpha-induced apoptosis. In good correlation, cells overexpressing AP-2alpha showed a reduction in mitochondrial membrane potential (Deltapsi(m)), cytochrome c and Smac/DIABLO release into cytosol, and Bax translocation into mitochondria. We found that the pro-apoptotic protein Bax is important for AP-2alpha-induced apoptosis as adenovirus AP2 failed to induce apoptosis in HCT116 Bax(-/-) cells. However, we found the IAP (inhibitor of apoptosis) inhibitor Smac/DIABLO may have a limited role in AP-2alpha-induced apoptosis as we found the IAP member Survivin down-regulated by AP-2alpha. Although the total Bax level remains unaltered, we found a time-dependent increase in the activated form of Bax in adenovirus AP2-infected cells. In addition, we show that AP-2alpha transcriptionally represses Bcl-2 by binding to its promoter both in vitro and in vivo and that this is essential for AP-2alpha-induced apoptosis as ectopic expression of Bcl-2 efficiently inhibited apoptosis induced by AP-2alpha. Furthermore, we show that chemotherapy-induced endogenous AP-2alpha down-regulates Bcl-2 and induces apoptosis in an AP-2alpha-dependent manner. Moreover, we demonstrate that inhibition of okadaic acid or staurosporine-sensitive pathways in AP-2alpha overexpressing breast cancer cells resulted in AP-2alpha-dependent apoptosis induction. These results suggest that AP-2alpha induces apoptosis by down-regulating Bcl-2 and utilizing a bax/cytochrome c/Apaf1/caspase 9-dependent mitochondrial pathway.

Upregulation of ASCL1 and inhibition of Notch signaling pathway characterize progressive astrocytoma

Astrocytoma is the most common type of brain cancer constituting more than half of all brain tumors. With an aim to identify markers describing astrocytoma progression, we have carried out microarray analysis of astrocytoma samples of different grades using cDNA microarray containing 1152 cancer-specific genes. Data analysis identified several differentially regulated genes between normal brain tissue and astrocytoma as well as between grades II/III astrocytoma and glioblastoma multiforme (GBM; grade IV). We found several genes known to be involved in malignancy including Achaete-scute complex-like 1 (Drosophila) (ASCL1; Hash 1). As ASCL has been implicated in neuroendocrine, medullary thyroid and small-cell lung cancers, we chose to examine the role of ASCL1 in the astrocytoma development. Our data revealed that ASCL1 is overexpressed in progressive astrocytoma as evidenced by increased levels of ASCL1 transcripts in 85.71% (6/7) of grade II diffuse astrocytoma (DA), 90% (9/10) of grade III anaplastic astrocytoma (AA) and 87.5% (7/8) of secondary GBMs, while the majority of primary de novo GBMs expressed similar to or less than normal brain levels (66.67%; 8/12). ASCL1 upregulation in progressive astrocytoma is accompanied by inhibition of Notch signaling as seen by uninduced levels of HES1, a transcriptional target of Notch1, increased levels of HES6, a dominant-negative inhibitor of HES1-mediated repression of ASCL1, and increased levels of Notch ligand Delta1, which is capable of inhibiting Notch signaling by forming intracellular Notch ligand autonomous complexes. Our results imply that inhibition of Notch signaling may be an important early event in the development of grade II DA and subsequent progression to grade III AA and secondary GBM. Furthermore, ASCL1 appears to be a putative marker to distinguish primary GBM from secondary GBM.

Activator Protein 2α Status Determines the Chemosensitivity of Cancer Cells: Implications in Cancer Chemotherapy

Cancer chemotherapeutic drugs induce apoptosis by several pathways. Inactivation of proapoptotic genes, or activation of survival signaling, leads to chemoresistance. Activator protein 2alpha (AP-2alpha), a developmentally regulated sequence-specific DNA-binding transcription factor, has been shown to function like a tumor suppressor. Here, we show that controlled expression of AP-2alpha, using tetracycline-inducible system, increased the chemosensitivity of cancer cells by severalfold by sensitizing cells to undergo apoptosis upon chemotherapy. Under these conditions, neither AP-2alpha expression nor drug treatment resulted in apoptosis induction, whereas in combination the cancer cells underwent massive apoptosis. We found that endogenous AP-2alpha protein is induced posttranscriptionally by various chemotherapeutic drugs. Blocking the endogenous AP-2alpha by small interfering RNA in human cancer cells lead to decreased apoptosis, increased colony formation, and chemoresistance irrespective of their p53 status upon chemotherapy. We further show that 5-aza-2'-deoxycytidine induced reexpression of AP-2alpha in MDA-MB-231 breast cancer cells (wherein AP-2alpha expression is silenced by hypermethylation), resulted in massive apoptosis induction, increased chemosensitivity, decreased colony formation, and loss of tumorigenesis upon chemotherapy. However, in MDA-MB-231 cells transfected with AP-2alpha small interfering RNA, 5-aza-2'-deoxycytidine treatment failed to increase apoptosis and chemosensitivity. The treatment also resulted in increased colony formation and efficient tumor formation upon chemotherapy. These results establish an important role for AP-2alpha in cancer cell chemosensitivity and provide new insights for modifying the chemosensitivity of cancer cells by activating apoptotic pathways.

p73 beta-expressing recombinant adenovirus: a potential anticancer agent

Tumor suppressor p53-based gene therapy strategy is ineffective in certain conditions. p73, a p53 homologue, could be a potential alternative gene therapy agent as it has been found to be an important determinant of chemosensitivity in cancer cells. Previously, we have reported the generation of a replication-deficient adenovirus expressing p73 beta (Ad-p73). In this study, we evaluated the therapeutic potential of Ad-p73 against a panel of cancer cells (n=12) of different tissue origin. Ad-p73 infected all the cell lines tested very efficiently resulting in several-fold increase in p73 beta levels, which is also functional as it activated the known target gene p21(WAF1/CIP1). Infection with Ad-p73 resulted in potent cytotoxicity in all the cell lines tested. The mechanism of p73-induced cytotoxicity in these cell lines is found to be due to a combination of cell cycle arrest and induction of apoptosis. In addition, exogenous overexpression of p73 by Ad-p73 infection increased the chemosensitivity of cancer cells by many fold to commonly used drug adriamycin. Moreover, Ad-p73 is more efficient than Ad-p53 in enhancing the chemosensitivity of mutant p53 harboring cells. Furthermore, Ad-p73 infection did not induce apoptosis in human normal lung fibroblasts (HEL 299) and human immortalized keratinocytes (HaCaT). These results suggest that Ad-p73 is a potent cytotoxic agent specifically against cancer cells and could be developed as a cancer gene therapy agent either alone or in combination with chemotherapeutic agents.

Role of p53 status in chemosensitivity determination of cancer cells against histone deacetylase inhibitor sodium butyrate

Histone deacetylases inhibitors (HDIs) induce growth arrest and apoptosis in a variety of human cancer cells. Sodium butyrate (NaB), a histone deacetylase inhibitor, has been shown to cause a G(1) cell cycle arrest by inducing p21(WAF1/CIP1) in a p53-independent manner. In this report, we present evidence for activation of p53 pathway by NaB and its role in the NaB-mediated growth suppression. Addition of NaB increased the levels of p53 involving a p14(ARF)-dependent post-transcriptional mechanism. NaB induced p53 is functional as it activated p53-specific reporter, induced the level of p21(WAF1/CIP1), inhibited cellular DNA synthesis and induced apoptosis. By using HPV 16 E6 stable transfectants as well as p53 null cancer cells, we show that NaB suppresses the growth of WT p53 containing cells more efficiently. NaB inhibited DNA synthesis to similar extent both in the presence and absence of p53. However, NaB treatment lead to a major G(2)/M arrest of cells in the presence of p53, while cells without wild-type p53 accumulated mainly in G(1) phase of the cell cycle. Furthermore, apoptosis induction by NaB is greatly reduced in the absence of p53. These results suggest that p53 pathway mediates in part growth suppression by NaB and the p53 status may be an important determinant of chemosensitivity in HDI based cancer chemotherapy.

Mechanism of Cytotoxicity of Copper(I) Complexes of 1,2-Bis(diphenylphosphino)ethane

The cytotoxic properties of arylphosphines are regulated by metals. We have synthesized a series of copper(I) complexes of 1,2-bis(diphenylphosphino)ethane (DPPE) and tested their in vitro cytotoxicity in a human lung carcinoma cell line H460. One of the complexes [Cu(2)(DPPE)(3)(CH(3)CN)(2)](ClO(4))(2) (C1), showed maximum cytotoxicity comparable to that of adriamycin. Treatment of cells with C1 caused DNA damage in vitro and activated the p53 pathway. Flow cytometry revealed that growth inhibition by C1 was due to a combination of cell cycle arrest and apoptosis. Simultaneous addition of C1 and adriamycin increased the cytotoxicity of either compound, suggesting the potential use of adriamycin in combination with C1. DNA binding and simulation studies suggest that adriamycin binds to DNA synergistically in the presence of C1. Thus, we have identified C1, a copper(I) complex of DPPE, as a potential chemotherapeutic drug for further testing, which could be used either alone or in combination with other chemotherapeutic drugs.

Expression profiling of sodium butyrate (NaB)-treated cells: identification of regulation of genes related to cytokine signaling and cancer metastasis by NaB

Histone deacetylase (HDAC) inhibitors induce growth arrest and apoptosis in a variety of human cancer cells. Sodium butyrate (NaB), a short chain fatty acid, is a HDAC inhibitor and is produced in the colonic lumen as a consequence of microbial degradation of dietary fibers. In order to dissect out the mechanism of NaB-induced growth inhibition of cancer cells, we carried out expression profiling of a human lung carcinoma cell line (H460) treated with NaB using a cDNA microarray. Of the total 1728 genes analysed, there were 32 genes with a mean expression value of 2.0-fold and higher and 66 genes with a mean expression value 3.0-fold and lower in NaB-treated cells. For a few selected genes, we demonstrate that their expression pattern by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis is matching with the results obtained by microarray analysis. Closer view at the expression profile of NaB-treated cells revealed the downregulation of a total of 16 genes associated with cytokine signaling, in particular, interferon gamma (IFNgamma) pathway. In good correlation, NaB-pretreated cells failed to induce interferon regulatory factor 1, an INFgamma target gene, efficiently upon IFNgamma addition. These results suggest that NaB inhibits proinflammatory cytokine signaling pathway, thus providing proof of mechanism for its anti-inflammatory activity. We also found that NaB induced three genes, which are known metastatic suppressors, and downregulated 11 genes, which have been shown to promote metastasis. Upregulation of metastatic suppressor Kangai 1 (KAI1) by NaB in a time-dependent manner was confirmed by RT-PCR analysis. The differential regulation of metastasis-associated genes by NaB provides explanation for the anti-invasive properties of NaB. Therefore, our study presents new evidence for pathways regulated by NaB, thus providing evidence for the mechanism behind anti-inflammatory and antimetastatic activities of NaB.

Pharmacogenomics in breast cancer: current trends and future directions

Pharmacogenomics is the study of genetic variations between individuals to predict the risk of toxic side effects and the probability that a patient will respond to single- or multidrug chemotherapy. Breast cancer remains one of the most common cancers among women worldwide and is second only to lung cancer in cancer-related death. A better understanding of the mechanisms of initiation and progression of breast cancer is needed for early diagnosis and development of better therapeutic methodologies. Differences in cancer patients' responses to chemotherapy have often been attributed to pathogenesis and severity of the disease, drug interactions, patient's age, gender, nutritional status, organ functions and tumor biology. It is now well recognized that genetic variations in drug target genes, disease pathway genes and drug metabolizing enzymes can have greater influence on drug efficacy and toxicity. In addition, germline variants can be used to study breast cancer susceptibility, as well as the variable response to both drug and radiation therapy used in the treatment of breast cancer. This review discusses clinically relevant individual gene variations that influence breast cancer susceptibility and cancer therapy, as well as the microarray-based expression profiling studies that have great potential in cancer pharmacogenomics in terms of tumor classification, drug and biomarker discovery and drug efficacy testing.