ATM in breast and brain tumors: a comprehensive review.

The ATM gene is mutated in the syndrome, ataxia-telangiectasia (AT), which is characterized by predisposition to cancer. Patients with AT have an elevated risk of breast and brain tumors Carrying mutations in ATM, patients with AT have an elevated risk of breast and brain tumors. An increased frequency of ATM mutations has also been reported in patients with breast and brain tumors; however, the magnitude of this risk remains uncertain. With the exception of a few common mutations, the spectrum of ATM alterations is heterogeneous in diverse populations, and appears to be remarkably dependent on the ethnicity of patients. This review aims to provide an easily accessible summary of common variants in different populations which could be useful in ATM screening programs. In addition, we have summarized previous research on ATM, including its molecular functions. We attempt to demonstrate the significance of ATM in exploration of breast and brain tumors and its potential as a therapeutic target.

Expression Patterns of CXCL12 and its Receptor in Colorectal Carcinoma.

BACKGROUND: Stromal cell-derived factor-1 (also called CXCL12) and its receptor, CXCR4, have a key role in the pathogenesis and tumorigenesis of various cancers. The aims of the current study were to quantitatively examine the expression of CXCR4 and CXCL12 genes in colorectal cancer and to correlate their expression degree with clinicopathological features. METHODS: Tumor tissue samples were collected from 47 patients with CRC. Total RNA was isolated from resection tissues and real-time PCR analysis was performed to examine mRNA levels of CXCL12 and CXCR4 genes. RESULTS: No significant differences were observed for both CXCL12 and CXCR4 between tumor tissues and the adjacent non-affected tissues, although a borderline significant correlation (p = 0.052) were detected between gene expression of CXCL12 and CXCR4 in tumor tissues. Our results also indicated that there was no significant correlation between expression pattern of CXCL12/CXCR4 and clinicopathological variables. CONCLUSIONS: Our data showed that CXCL12 and CXCR4 are expressed simultaneously in colorectal carcinoma tissues, suggesting that expression of these chemokines and corresponding receptors may play a pivotal role in colorectal tumorigenesis, although it cannot be as a predictive factor for disease progression.

Deregulated expression of HDAC3 in colorectal cancer and its clinical significance.

BACKGROUND: To date, 4 classes of histone deacetylases (HDACs) have been identified in humans. Class I HDACs are zinc-dependent and NAD+-independent enzymes, and include 4 isoforms closely related to yeast RPD3: HDAC1, 2, 3, and 8. OBJECTIVES: The aims of the study were to quantitatively evaluate the expression of HDAC3 in colorectal cancer (CRC) and to correlate its expression levels with clinicopathological parameters. MATERIAL AND METHODS: We characterized expression patterns of HDAC3 as class I HDAC isoforms in a cohort of 48 CRC patients by quantitative (real-time) reverse transcription polymerase chain reaction (RT-PCR). In addition, the potential relationship between HDAC3 expression levels and clinicopathological parameters in patients suffering from CRC was explored. RESULTS: We found that HDAC3 was highly expressed in colorectal tumors compared to normal colorectal tissues (p < 0.05). Furthermore, we found significant correlations between HDAC3 expression levels and tumor differentiation grades (p < 0.05). CONCLUSIONS: In this prospective study we identified a pronounced HDAC3 expression pattern in CRC. Our findings support an important role of HDAC3 as a complementary molecular marker for existing histopathological diagnostic elements; it might also have applications in prognostic and targeted therapy. Furthermore, HDAC3 can be used as a biomarker to differentiate between tumor borders and margins, and it may also be useful for characterizing field cancerization in CRC.

Variants in GNPTAB, GNPTG and NAGPA genes are associated with stutterers.

Non-syndromic stuttering is a neurodevelopmental disorder characterized by disruptions in normal flow of speech in the form of repetition, prolongation and involuntary halts. Previously, mutations with more severe effects on GNPTAB and GNPTG have been reported to cause Mucolipidosisll (ML-ll) and Mucolipidosislll (ML-lll), two lysosomal storage disorders with multiple pathologies. We used homozygosity mapping and Sanger sequencing to investigate variants of the three genes in 25 Iranian families with at least two first degree related non-syndromic stutterers. Bioinformatic evaluation and Segregation analysis of the found variants helped us define probable consequences. We also compared our findings with those related to Mucolipidosis. 14 variations were found in the three genes 3 of which, including a novel variant within intronic region of GNPTG and a heterozygous 2-bp deletion in coding region of GNPTAB, co-segregated with stuttering in the families they were found. Bioinformatics analysis predicted all three variants causing deleterious effects on gene functioning. Our findings support the role of these three variants in non-syndromic stuttering. This finding may challenge the current belief that variations causing stuttering are at different sites and have less severe consequences than genetic changes that cause ML-ll and ML-lll.

Prognostic significance of MYCN gene amplification and protein expression in primary brain tumors: Astrocytoma and meningioma.

BACKGROUND: Astrocytoma and meningioma are the most common primary brain tumors. MYCN as a member of MYC proto-oncogenes has recently appeared as an attractive therapeutic target. Functions of MYCN are critical for growth of nervous system and neural differentiation. OBJECTIVE: We examined MYCN amplification and protein expression in astrocytoma and meningioma cases. METHODS: In this study, we used real-time PCR, FISH assay and flowcytometry to analyze DNA amplification and protein expression of MYCN. RESULTS: Among 30 samples of brain tumor, 14 cases (46.6%) revealed MYCN amplification. High-protein expression of MYCN was also observed in 43.3% of patients. There was a significant correlation between MYCN gene amplification and protein expression (r= 0.523; p= 0.003), interestingly five case showed discrepancy between the gene amplification and protein expression. Although MYCN amplification fails to show correlation with poor prognosis (p= 0.305), protein high-expression of MYCN significantly reduce disease-free survival (p= 0.019). CONCLUSIONS: Our results challenge the concept of the neural specificity of MYCN by demonstrating contribution of MYCN in meningioma. Moreover, this study highlights the importance of research at both level of DNA and protein, to determine the biological functions and medical impacts of MYCN.

Clinical significance of NDRG3 in patients with breast cancer.

AIM: The expression level of NDRG3 gene is investigated among breast cancer (BC) patients. METHODS: Real-time quantitative PCR was performed. RESULTS:  NDRG3 was downregulated in BC patients particularly in advanced stage of the disease. HER2 status was significantly correlated with the expression of NDRG3. Also, triple-negative BC patients showed low levels of NDRG3 expression in comparison to other subtypes. Lastly, the expression of NDRG3 had significant impact on survival, with NDRG3 downregulated patients having the worst event-free survival rate among others. CONCLUSION: We have presented that NDRG3 might be a tumor suppressor candidate. NDRG3 downregulation might be involved in the tumorigenesis and development of invasive BC in an advanced phase of the disease.

High expression of CEACAM19, a new member of carcinoembryonic antigen gene family, in patients with breast cancer.

Carcinoembryonic antigen (CEA) family members play important roles in malignancies and are introduced as biomarkers in different types of cancers. Among them CEACAM19 (CEAL1) gene, a new member of the CEA family, remains to be fully elucidated. The aim of this study was investigating the mRNA expression level of CEACAM19 in tumor samples of breast cancer patients compared to breast tissue of normal individuals. We evaluated the expression level of this gene in 75 breast tumors by using real-time quantitative PCR. Also, we studied the correlation between CEACAM19 expression and clinicopathological features and hormone receptors status, including estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 of patients. Out of the enrolled patients, six of them (7.9%) showed low expression, ten (13.2%) showed normal expression and 59 (77.6%) showed high expression of CEACAM19. There was a significant correlation between high expression of CEACAM19 gene in tumor samples compared to normal tissues (P = 0.039). No significant correlation was seen between clinicopathological factors and disease-free survival with mRNA levels of CEACAM19 in tumor samples, while the difference between the expression of CEACAM19 in ER/PR-positive and ER/PR-negative breast cancer patients was statistically significant (P = 0.046). In conclusion, CEACAM19 showed high expression in tumor samples compared to normal mammary tissue. In addition, CEACAM19 may represent as a novel therapeutic target in certain subgroups of breast cancer patients such as ER/PR-negative. Critical roles of CEA proteins in tumor progression may nominate them as robust potential targets for therapeutic intervention in near future.

Spectrum of MYBPC3 Gene Mutations in Patients with Hypertrophic Cardiomyopathy, Reporting Two Novel Mutations from North-West of Iran.

BACKGROUND: Hypertrophic cardiomyopathy (HCM) is the leading cause of sudden cardiac death (SCD) in children and young adults and is the most frequent genetically determined cardiovascular disease following autosomal dominant pattern of inheritance. A number of genes have been shown to be responsible for HCM including MYBPC3. Cmybc, the protein encoded by MYBPC3 is a sarcomeric thick filament protein that interacts with titin, myosin, and actin to control sarcomeric gathering. Mutations in the MYBPC3 gene have been found to be associated with a history of sudden cardiac death in HCM patients. The main objective of the present study was to investigate the type and frequency of mutations in the MYBPC3 gene in HCM patients from the North-West of Iran. METHODS: All the exons and exon-intron flanking regions of the MYBPC3 gene were assessed by PCR-SSCP, and the PCR products with divergent pattern of bands on polyacrylamide gel were sent for bi-directional sequencing. RESULTS: Mutational screening of a cohort of 42 HCM cases led to the identification of 14 MYBPC3 variations. Three cases out of those variations were frameshift, 1 case was splice site, 3 cases were missense, 2 cases were synonymous, and 5 cases were intronic variants. MYBPC3 mutations (28.5%) represent the most prevalent cause of inherited HCM. The age of onset was 39.3 in MYBPC3 carrier patients. Multiple gene mutations were recognized in 1 case (2.3%). CONCLUSIONS: The results obtained from the present study indicate a significant role of MYBPC3 gene mutations in HCM disease and can be used for pre-symptomatic diagnosis of at risk family members of affected individuals.

STC1 and NF-κB p65 (Rel A) is Constitutively Activated in Colorectal Cancer.

BACKGROUND: Stanniocalcin-1 (STC1) and nuclear factor (NF)-κB subunit p65 transcription factor are involved in various types of human malignancies. The roles of STC1 and NFκB-p65 in colorectal cancer (CRC) are still not fully understood. We investigated expression levels of NF-κB p65 and STC1 and also correlations between STC1 and NF-κB p65 expression and clinicopathological features in CRC. METHODS: Tumor tissue samples were collected from 48 patients with CRC. RT-PCR and Real-time PCR analysis was performed to examine mRNA levels of STC1 and NF-κB p65. RESULTS: The relative mRNA levels of STC1 and NF-κB p65 were significantly higher in tumor tissues than in adjacent mucosa (p = 0.025 and p = 0.044, respectively). The data also showed that STC1 and NF-κB p65 mRNA levels were not significantly associated with clinicopathological characteristics. In addition, there was no association between expression levels of STC1 and NF-κB p65 in tumor samples. CONCLUSIONS: Our data indicate that STC1 and NF-κBp65 is activated constitutively in colorectal carcinoma tissues, suggesting that activation of these factors might play an important role in colorectal tumorigenesis. Future studies should examine STC1 and NF-κBp65 as a molecular target for the treatment of CRC.

BCL-1 Gene Rearrangements in Iranian Non-Hodgkin Lymphoma Patients.

In the present study, our aim was to assess the incidence of BCL-1 gene rearrangements in formalin-fixed paraffin embedded (FFPE) tissue in patients with non-Hodgkin lymphomas (NHL). The BIOMED-2 protocol was applied to assess the BCL-1 gene rearrangements in NHL patients. PCR amplification was carried out on FFPE in 100 patients with B-cell lymphoma including 89 cases with diffused large B-cell lymphoma (DLBCL) (15 cases under 18 years old) and 11 cases with mantle cell lymphoma (MCL). Out of the 100 patients, 19 cases (19%) were identified to have concurrent translocation involving BCL-1. The significant association was seen between BCL-1 gene rearrangements and the lymphomas in patients older than 55 years (P<0.05). Out of 100 cases, 80 cases were positive and 20 cases were negative regarding CD20. No significant association was found between DLBCL lymphoma in patients under 18 years old and BCL-1 gene rearrangements (P>0.05). In addition, the positive and negative expressions of LCA/CD45 marker were 76% (76/100) and 26% (26/100), respectively. Our findings revealed that BCL-1 gene rearrangement assays using BIOMED-2 protocol can be considered as a valuable approach in detection of the lymphomas.

HER2 gene amplification in patients with prostate cancer: Evaluating a CISH-based method.

Prostate cancer (PCa) is one of the most widespread malignancies in the world. The role of the human epidermal growth factor receptor 2 (HER2) in the pathogenesis and progression of human PCa remains poorly understood. In contradiction with breast cancer, studies on HER2 overexpression and gene amplification in PCa have produced varying results, although the HER2 oncogene has been implicated in the biology of numerous tumor types, and serves as a prognostic marker and therapeutic target in breast cancer. Technical challenges are considered the main reasons for data discrepancies. Amplification of the HER2 gene has previously been reported in PCa, in which it was associated with tumor progression. The present study aimed to evaluate the prevalence and clinical significance of HER2 amplification in PCa. A total of 32 biopsy samples obtained from human prostate adenocarcinomas were evaluated by chromogenic in situ hybridization (CISH) to determine the frequency of patients with HER2 gene amplifications. High copy numbers of HER2 were detected in 19 of the prostate tumors analyzed. The results of the present study suggested that, in patients without amplification of HER2, high levels of prostate-specific antigen or a high Gleason score were not significantly correlated with a high pathologic stage. Furthermore, amplification levels of the HER2 gene were directly associated with pathologic stage in patients with PCa. Therefore, the potential use of HER2 as a prognostic factor or therapeutic target for PCa warrants further study.

Inhibitor of Aurora Kinase B Induces Differentially Cell Death and Polyploidy via DNA Damage Response Pathways in Neurological Malignancy: Shedding New Light on the Challenge of Resistance to AZD1152-HQPA.

Aurora kinase B (AURKB), a crucial regulator of malignant mitosis, is involved in chromosome segregation and cytokinesis. AZD1152-HQPA is a selective inhibitor for AURKB activity and currently bears clinical assessment for several malignancies. However, the effect of this drug still needs to be elucidated in neurological malignancies. In this study, we investigated the restrictive potentials of AZD1152-HQPA in U87MG and SK-N-MC. AZD1152-HQPA treatment resulted in growth arrest, modification of cell cycle, and inhibition of colony formation in both cell lines. Furthermore, lower concentrations of AZD1152-HQPA profoundly induced apoptosis in U87GM (p53/p73 wild type) cells in parallel with an upregulation of p53 and its target genes BAX, BAD, APAF1, and PUMA. But remarkably, SK-N-MC (p53/p73 double null) responded to AZD1152-HQPA at much higher concentrations with an upregulation of genes involved in cell cycle progression, induction of excessive endoreduplication, and polyploidy rather than apoptosis. Although SK-N-MC was resistant to AZD1152-HQPA, we did not find a mutation in the coding sequence of Aurora B gene or overexpressions of ABCG2 and ABCB1 as reported previously to be resistance mechanisms. However, our results suggest that p53/p73 status could be an important mechanism for the type of response and resistance of the tumor cells to AZD1152-HQPA. Collectively, inhibition of Aurora kinase B differentially induced cell death and polyploidy via DNA damage response pathways, depending on the status of p53/p73. We suggest p53/p73 could be a key regulator of sensitivity to AZD1152-HQPA and their status should be explored in clinical response to this ongoing drug in clinical trials.

Detection of aberrant methylated SEPT9 and NTRK3 genes in sporadic colorectal cancer patients as a potential diagnostic biomarker.

Colorectal cancer (CRC) is one of the most common malignancies, and the third leading cause of cancer mortality worldwide. Timely detection of CRC in patients with earlier stages provides the highest rate of survival. Epigenetic alterations are important in the occurrence and progression of CRC, and represent the primary modifications of cancer cells. Therefore, detection of these alterations in CRC cases are thought to hold great promise as diagnostic biomarkers. It has been shown that the SEPT9 and NTRK3 genes are aberrantly methylated and their detection can be used as biomarkers for early diagnosis of CRC. The present study analyzed promoter methylation status of these genes in CRC patients. Genomic DNA was extracted from 45 CRC and paired adjacent healthy tissues and undergone bisulfite conversion, and the methylation status of NTRK3 and SEPT9 were defined using the MS-HRM assay. Our results showed that there are statistically significant differences in methylation status of NTRK3 and specially SEPT9 between CRC and adjacent normal tissues (P<0.001). High sensitivity and specificity for a specific location in SEPT9 gene promoter as a diagnostic biomarker was observed. SEPT9 promoter hypermethylation may serve as a promising biomarker for the detection of CRC development. However, to validate the biomarker potential of NTRK3 there is a requirement for further investigation.

Molecular Analysis of IGH and Incomplete IGH D-J Clonality Gene Rearrangements in Hodgkin Lymphoma Malignancies.

BACKGROUND: We evaluated molecular clonality in immunoglobulin heavy chain (IGH) and incomplete IGH D-J genes for improvement of clinical diagnosis of Hodgkin's lymphoma (HL). We applied BIOMED-2 protocols in HL cases, which were previously approved by clonality detection in non-Hodgkin lymphoma (NHL) cases. METHODS: We investigated 50 consecutive FFPE samples of classical HL (cHL) patients to assess IGH and IGH D-J clonal gene rearrangements by multiplex PCR protocols, which were provided by the European Biomedicine and Health (BIOMED-2) Concerted Action Project BMH4-CT98-3936. RESULTS: In the present study, there was a monoclonality of 86% (43/50) including a clonality of 74% (37/50) for IGH and a clonality of 42% (21/50) in IGHD-J. In addition, a lack of clonality was detected in 14% (7/50) of cases. Frequent gene rearrangements were detected in framework (FR) III (54%) and FRII (20%), whereas no clonality was seen in FRI. Furthermore, a monoclonality of 28% and 14% was detected in the DH(1-6)-JH and DH(see symbol)-JH gene rearrangements, respectively. CONCLUSIONS: The present study suggests that the complete IGH and incomplete IGH D-J clonality gene rearrangement assays using BIOMED-2 protocols could be considered a valuable method for detection of clonal gene rearrangements, especially in HL cases.

Molecular Characterization of KRAS, BRAF, and EGFR Genes in Cases with Prostatic Adenocarcinoma; Reporting Bioinformatics Description and Recurrent Mutations.

BACKGROUND: Prostate cancer is one of the most common cancers which develops by mutations and/or other genetic alterations in specific genes. Regarding the previous studies in literature predominant mutations take place in KRAS, BRAF, and EGFR genes in special types of cancers. In this research, we attempt to identify the prevalence and significant role of the possible mutations in EGFR exons 18-21, KRAS codon 12, 13, and 61, and BRAF codon 600 mutations in tumoral tissue specimens from patients with prostatic adenocarcinoma. Furthermore, in this research, it has been attempted to investigate the molecular characteristics of these genes in terms of bioinformatic aspects. METHODS: A total of 35 prostatic adenocarcinoma fresh tissue samples, enriched in neoplastic cells, were obtained from the Cancer Institute of Iran. The presence of mutations at codons 12, 13 and 61 of KRAS, codon 600 of BRAF and EGFR exons 18-21 were determined by direct Sanger sequencing. To evaluate the molecular features, structure, and post-translation modification of those genes, a bioinformatics survey was performed using the SWISS-MODEL (http://swissmodel.expasy.org) and NetPhos 2.0 (http://www.cbs.dtu.dk/services/NetPhos/) Server. Also, using bioinformatics software, the phylogeny tree of the mutations was drawn. RESULTS: Mutations of codons 12 and 13 of KRAS were found in 2 of the 35 prostatic adenocarcinomas. Two cases carried homozygous mutations on exon 2 in codon 12 (G12V) and codon 13 (G13D). Also, no mutation was detected at BRAF codon 600 and EGFR exons 18-21 in any of the samples. CONCLUSIONS: Based on the group of patients with prostate adenocarcinoma, our research shows that the mutations in codons 12 and 13 of KRAS are the most common in prostate carcinomas. Noting these results and the molecular pathway of this gene, there is a possible more perceptible role for this gene in the pathogenesis of prostatic carcinoma. However, according to our finding, as in previous studies, the role of BRAF and EGFR gene mutations in prostate adenocarcinoma are less than in the KRAS gene and, therefore, we assume that these common mutations of the KRAS gene can be used as an early determining marker for early diagnosis of prostate adenocarcinoma. In the future, due to the complexity of etiological parameters in prostate cancer development, the case specific tumor molecular identification and treatment for each affected subject are urgently needed.

A Case of Tuberous Sclerosis Without Multiorgan Involvement.

Tuberous sclerosis or Tuberous sclerosis complex (TSC) is a relatively rare autosomal dominant and progressive neurocutaneous disorder involves multiple organs mainly brain, heart, kidney, lung, liver, skin and eye. The diagnosis is typically made clinically. Here, we are reporting a case of TSC presented mainly with dermatologic findings and only neurologic manifestations on MRI. A 15-year-old female with intellectual disability is followed up at neurology clinic for history of seizure. Intelligence evaluation showed that she has intellectual disability. She had wart like lesions distributed in form of butterfly over the face especially involving nose. She did not have any sign and symptom of heart, kidney, lung, bone and eye involvement. Also, her laboratory tests were normal. Despite the physical examination showed absolutely intact neurologic examination, but brain MRI and CT scan revealed several cortical and subcortical tubers, and subependymal glial nodules; no evidence of giant cell astrocytomas and aneurysm. Hypesignal foci are seen at subcortical white matter on long TR images. Fibers are involved. In this case, there is no evidence of giant cell astrocytomas and aneurysm. It seems that TSC could be the prevalent disorder and referring intellectual disability patients in birth with normal organs could be diagnosed as TSC. Therefore, there is necessary need to design genetic natal and post natal tests for diagnosis of TSC cases. Also, there is pivotal that similar cases must be reported; perhaps TSC is more prevalent than to be considered.

Expression Analysis of Aurora-C and Survivin, Two Testis-Specific Genes, in Patients with Colorectal Cancer.

BACKGROUND: Colorectal cancer (CRC) is one of the leading causes of cancer-related death worldwide. The high frequency of positive families shows the importance of public awareness and screening strategies in those families. Cancer/testis (CT) antigens such as Aurora-C and Survivin are a group of antigens expressed in various tumor types of human cancers. Therefore, the aim of this study was to investigate the expression of Aurora-C and Survivin genes in malignant and normal tissues and their correlation to clinicopathological characteristics. METHODS: Tumor samples were obtained from 33 patients and adjacent non-tumorous tissues from 7 patients were also used as control. Patients were diagnosed with various stages of colorectal cancer. The level of Aurora-C and Survivin genes were evaluated by using real-time quantitative Polymerase Chain Reaction. RESULTS: The expression pattern of Survivin and Aurora-C revealed significant changes in tumor tissues when compared with normal tissues (p < 0.05). Also, these expressions were associated with the grade of disease and tumor size. There was no significant relationship between the expression of Survivin and Aurora-C genes (p > 0.05). CONCLUSIONS: In conclusion, the overexpression of Aurora-C and Survivin genes may play an important role in the development of colorectal cancer and may play a potential role in cancer therapy.

Expression Analysis of p16, c-Myc, and mSin3A in Non-small Cell Lung Cancer by Computer Aided Scoring and Analysis (CASA).

BACKGROUND: Immunohistochemical analysis (IHC) of tissue microarray (TMA) slides enables large sets of tissue samples to be analyzed simultaneously on a single slide. However, manual evaluation of small cores on a TMA slide is time consuming and error prone. METHODS: We describe a computer aided scoring and analysis (CASA) method to allow facile and reliable scoring of IHC staining using TMA containing 300 non-small cell lung cancer (NSCLC) cases. In the two previous published papers utilizing our TMA slides of lung cancer we examined 18 proteins involved in the chromatin machinery. We developed our study using more proteins of the chromatin complex and several transcription factors that facilitate the chromatin machinery. Then, a total of 78 antibodies were evaluated by CASA to derive a normalized intensity value that correlated with the overall staining status of the targeting protein. The intensity values for TMA cores were then examined for association to clinical variables and predictive significance individually and with other factors. RESULTs: Using our TMA, the intensity of several protein pairs were significantly correlated with an increased risk of death in NSCLC. These included c-Myc with p16, mSin3A with p16 and c-Myc with mSinA. Predictive values of these pairs remained significant when evaluated based on standard IHC scores. CONCLUSIONS: Our results demonstrate the usefulness of CASA as a valuable tool for systematic assessment of TMA slides to identify potential predictive biomarkers using a large set of primary human tissues.

Carbon nanotubes part I: preparation of a novel and versatile drug-delivery vehicle.

INTRODUCTION: It is 23 years since carbon allotrope known as carbon nanotubes (CNT) was discovered by Iijima, who described them as "rolled graphite sheets inserted into each other". Since then, CNTs have been studied in nanoelectronic devices. However, CNTs also possess the versatility to act as drug- and gene-delivery vehicles. AREAS COVERED: This review covers the synthesis, purification and functionalization of CNTs. Arc discharge, laser ablation and chemical vapor deposition are the principle synthesis methods. Non-covalent functionalization relies on attachment of biomolecules by coating the CNT with surfactants, synthetic polymers and biopolymers. Covalent functionalization often involves the initial introduction of carboxylic acids or amine groups, diazonium addition, 1,3-dipolar cycloaddition or reductive alkylation. The aim is to produce functional groups to attach the active cargo. EXPERT OPINION: In this review, the feasibility of CNT being used as a drug-delivery vehicle is explored. The molecular composition of CNT is extremely hydrophobic and highly aggregation-prone. Therefore, most of the efforts towards drug delivery has centered on chemical functionalization, which is usually divided in two categories; non-covalent and covalent. The biomedical applications of CNT are growing apace, and new drug-delivery technologies play a major role in these efforts.

Carbon nanotubes part II: a remarkable carrier for drug and gene delivery.

INTRODUCTION: Carbon nanotubes (CNT) have recently been studied as novel and versatile drug and gene delivery vehicles. When CNT are suitably functionalized, they can interact with various cell types and are taken up by endocytosis. AREAS COVERED: Anti-cancer drugs cisplatin and doxorubicin have been delivered by CNT, as well as methotrexate, taxol and gemcitabine. The delivery of the antifungal compound amphotericin B and the oral administration of erythropoietin have both been assisted using CNT. Frequently, targeting moieties such as folic acid, epidermal growth factor or various antibodies are attached to the CNT-drug nanovehicle. Different kinds of functionalization (e.g., polycations) have been used to allow CNT to act as gene delivery vectors. Plasmid DNA, small interfering RNA and micro-RNA have all been delivered by CNT vehicles. Significant concerns are raised about the nanotoxicology of the CNT and their potentially damaging effects on the environment. EXPERT OPINION: CNT-mediated drug delivery has been studied for over a decade, and both in vitro and in vivo studies have been reported. The future success of CNTs as vectors in vivo and in clinical application will depend on achievement of efficacious therapy with minimal adverse effects and avoidance of possible toxic and environmentally damaging effects.