Combination of taxol and Bcl-2 siRNA induces apoptosis in human glioblastoma cells and inhibits invasion, angiogenesis and tumour growth

Applications of CRISPR-Cas9 Technology to Genome Editing in Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is an aggressive malignancy of the brain and spinal cord with a poor life expectancy. The low survivability of GBM patients can be attributed, in part, to its heterogeneity and the presence of multiple genetic alterations causing rapid tumor growth and resistance to conventional therapy. The Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-CRISPR associated (Cas) nuclease 9 (CRISPR-Cas9) system is a cost-effective and reliable gene editing technology, which is widely used in cancer research. It leads to novel discoveries of various oncogenes that regulate autophagy, angiogenesis, and invasion and play important role in pathogenesis of various malignancies, including GBM. In this review article, we first describe the principle and methods of delivery of CRISPR-Cas9 genome editing. Second, we summarize the current knowledge and major applications of CRISPR-Cas9 to identifying and modifying the genetic regulators of the hallmark of GBM. Lastly, we elucidate the major limitations of current CRISPR-Cas9 technology in the GBM field and the future perspectives. CRISPR-Cas9 genome editing aids in identifying novel coding and non-coding transcriptional regulators of the hallmarks of GBM particularly in vitro, while work using in vivo systems requires further investigation.

Small interfering RNA (siRNA) to target genes and molecular pathways in glioblastoma therapy: Current status with an emphasis on delivery systems

Glioblastoma multiforme (GBM) is one of the worst brain tumors arising from glial cells, causing many deaths annually. Surgery, chemotherapy, radiotherapy and immunotherapy are used for GBM treatment. However, GBM is still an incurable disease, and new approaches are required for its successful treatment. Because mutations and amplifications occurring in several genes are responsible for the progression and aggressive behavior of GBM cells, genetic approaches are of great importance in its treatment. Small interfering RNA (siRNA) is a new emerging tool to silence the genes responsible for disease progression, particularly cancer. SiRNA can be used for GBM treatment by down-regulating genes such as VEGF, STAT3, ELTD1 or EGFR. Furthermore, the use of siRNA can promote the chemosensitivity of GBM cells. However, the efficiency of siRNA in GBM is limited via its degradation by enzymes, and its off-targeting effects. SiRNA-loaded carriers, especially nanovehicles that are ligand-functionalized by CXCR4 or angiopep-2, can be used for the protection and targeted delivery of siRNA. Nanostructures can provide a platform for co-delivery of siRNA plus anti-tumor drugs as another benefit. The prepared nanovehicles should be stable and biocompatible in order to be tested in human studies.

Switching from Conventional to Nano-natural Phytochemicals to Prevent and Treat Cancers: Special Emphasis on Resveratrol

BACKGROUND

Natural phytochemicals and their derivatives have been used in medicine since prehistoric times. Natural phytochemicals have potential uses against various disorders, including cancers. However, due to low bioavailability, their success in clinical trials has not been reproduced. Nanotechnology has played a vital role in providing new directions for diagnosis, prevention, and treatment of different disorders, and of cancer in particular. Nanotechnology has demonstrated the capability to deliver conventional natural products with poor solubility or a short half-life to target specific sites in the body and regulate the release of drugs. Among the natural products, the phytoalexin resveratrol has demonstrated therapeutic effects, including antioxidant, antiinflammatory, and anti-proliferative effects, as well as the potential to inhibit the initiation and promotion of cancer. However, low water solubility and extensive first-pass metabolism lead to poor bioavailability of resveratrol, hindering its potential. Conventional dosage forms of resveratrol, such as tablets, capsules, dry powder, and injections, have met with limited success. Nanoformulations are now being investigated to improve the pharmacokinetic characteristics, as well as to enhance the bioavailability and targetability of resveratrol.

OBJECTIVES

This review details the therapeutic effectiveness, mode of action, and pharmacokinetic limitations of resveratrol, as well as discusses the successes and challenges of resveratrol nanoformulations. Modern nanotechnology techniques to enhance the encapsulation of resveratrol within nanoparticles and thereby enhance its therapeutic effects are emphasized.

CONCLUSION

To date, no resveratrol-based nanosystems are in clinical use, and this review would provide a new direction for further investigations on innovative nanodevices that could consolidate the anticancer potential of resveratrol.

Ganoderic acid A/DM-induced NDRG2 over-expression suppresses high-grade meningioma growth

PURPOSE

N-myc downstream-regulated gene 2 (NDRG2) is down-regulated in grade-III meningioma [anaplastic meningioma (AM)] and associated with clinically aggressive behavior. Current therapies in the treatment of high-grade meningioma are lacking with limited success. This study aims to validate the effect of NDRG2-targeted therapy using structurally related bioactive triterpene compounds derived from the edible mushroom Ganoderma lucidum (ganoderic acid A:GA-A/ganoderic acid DM:GA-DM) in human AM in relevant pre-clinical models.

METHODS

Tissue samples from the AM tumor regions of three human patients and control non-tumor samples were used to analyze the expression pattern of NDRG2. In vitro cell culture and in vivo cell-line-derived orthotopic xenograft animal models of AM were utilized to assess efficacy of treatment with GA-A/DM.

RESULTS

Downregulation of NDRG2 expression was observed in surgically resected high-grade meningiomas compared to normal brain. These results prompt us to use NDRG2-targeting agents GA-A/DM. In vitro results showed that 72-h treatments of 25 µM GA-A/DM induced AM cell death, upregulate NDRG2 protein expression, downregulate NDRG2 promoter methylation in meningioma cells as compared to azacitidine and decitabine, the most commonly used demethylating agents. Our results also demonstrated that GA-A/DM does not have any detrimental effect on normal human neurons and arachnoid cells. GA-A/DM promoted apoptotic factors (Bax) while suppressing MMP-9, p-P13K, p-AKT, p-mTOR, and Wnt-2 protein expression. RNAi-mediated knockdown of NDRG2 protein expression increased tumor proliferation, while forced expression of wt-NDRG2 decreased proliferation in an in vitro model. Magnetic resonance (MR) imaging and Hematoxylin (H&E) staining demonstrated gross reduction of tumor volume in GA-A/DM treated mice at 5 weeks when compared with saline-treated orthotopic AM xenografted controls. There was an overall decrease in tumor cell proliferation with increased survival in GA-A/DM-treated animals. Enzyme assays showed that GA-A/DM did not negatively impact hepatic function.

CONCLUSION

GA-A/DM may be a promising natural therapeutic reagent in the treatment of AM by suppressing growth via NDRG2 modulation and altering of intracellular signal pathways. We have shown it could potentially be an effective treatment for AM with decreased cellular proliferation in vitro, decreased tumor volume and increased survival in vivo.

Strategic use of nanotechnology in drug targeting and its consequences on human health: A focused review

Since the development of first lipid-based nanocarrier system, about 15% of the present pharmaceutical market uses nanomedicines to achieve medical benefits. Nanotechnology is an advanced area to meliorate the delivery of compounds for improved medical diagnosis and curing disease. Nanomedicines are gaining significant interest due to the ultra small size and large surface area to mass ratio. In this review, we discuss the potential of nanotechnology in delivering of active moieties for the disease therapy including their toxicity evidences. This communication will help the formulation scientists in understanding and exploring the new aspects of nanotechnology in the field of nanomedicine.

A strategy using mesoporous polymer nanospheres as nanocarriers of Bcl-2 siRNA towards breast cancer therapy

Small interference RNA (siRNA) has demonstrated unprecedented potential as a therapy for drug-resistant cancer. However, efficient cellular delivery is still a challenge due to hydrolytic sensitivity and poor cellular uptake of siRNA. Strategies to conjugate siRNA to the delivery vehicle and activate innate immunity have shown low in vivo efficacy. Therefore, nanomedicine approaches have become the main focus in this field. B-cell lymphoma 2 (Bcl-2) is the founding member of the Bcl-2 family of regulatory proteins that regulate cell death (apoptosis), by either inducing (pro-apoptotic) or inhibiting (anti-apoptotic) apoptosis. In this report, a nanomedicine system is constructed using Bcl-2 siRNA as the therapeutic agent and mesoporous polymer nanosphere (MPN) carriers to both improve cellular internalization and achieve Bcl-2 silencing and cell apoptosis. MPNs were prepared through a two-stage hydrothermal process at two different temperatures, which was deliberately designed to form nanospheres via self-assembly and create mesoporous structures by removing the pore-forming templates. Such MPNs were proved to be biodegradable. Without any carbonization process, MPNs still keep many active groups which endow them with excellent properties for functionalization purposes. Finally, the FA-targeted-Bcl-2-siRNA-loaded nanoparticles were constructed by a layer-by-layer assembly by electrostatic interactions after nitrification. These nanoparticles were efficiently delivered into breast cancer (BC) cells, showing a significant sequence-specific inhibition of Bcl-2 mRNA expression in BC cells, enhanced tumor cell apoptosis and tumor therapeutic efficacy. Taken together, this study establishes a novel therapeutic system for cancer therapy.

Autophagic and Apoptotic Pathways as Targets for Chemotherapy in Glioblastoma

Glioblastoma multiforme is the most malignant and aggressive type of brain tumor, with a mean life expectancy of less than 15 months. This is due in part to the high resistance to apoptosis and moderate resistant to autophagic cell death in glioblastoma cells, and to the poor therapeutic response to conventional therapies. Autophagic cell death represents an alternative mechanism to overcome the resistance of glioblastoma to pro-apoptosis-related therapies. Nevertheless, apoptosis induction plays a major conceptual role in several experimental studies to develop novel therapies against brain tumors. In this review, we outline the different components of the apoptotic and autophagic pathways and explore the mechanisms of resistance to these cell death pathways in glioblastoma cells. Finally, we discuss drugs with clinical and preclinical use that interfere with the mechanisms of survival, proliferation, angiogenesis, migration, invasion, and cell death of malignant cells, favoring the induction of apoptosis and autophagy, or the inhibition of the latter leading to cell death, as well as their therapeutic potential in glioma, and examine new perspectives in this promising research field.

Polyethylenimine-Spherical Nucleic Acid Nanoparticles against Gli1 Reduce the Chemoresistance and Stemness of Glioblastoma Cells

Glioblastoma (GBM) is the most common and lethal primary brain tumor in adults, with nearly 100% of patients ultimately succumbing to the disease. Median patient survival is 15 months, and no standard of care currently exists for recurrent cases. Glioma stem cells (GSCs), a rare and highly aggressive subpopulation of cells within these tumors, have recently emerged as drivers of tumor initiation and recurrence, and a growing body of evidence suggests that they must be completely eradicated to prevent relapse. Toward this goal, we have developed polyethylenimine-wrapped spherical nucleic acid nanoparticles (PEI-SNAs) targeting Gli1, a transcription factor within the Hedgehog signaling pathway that is crucial for the maintenance of GSCs. Here, we demonstrate that Gli1 PEI-SNAs bind scavenger receptors on GBM cells to undergo endocytosis in a caveolae/lipid raft/dynamin-dependent manner. They further achieve ∼30% silencing of tumor-promoting Hedgehog pathway genes and downstream target genes that promote the aggressive, chemoresistant phenotype of GBM. This produces a 30% decrease in proliferation that correlates with a robust onset of GBM cell senescence as well as an ∼60% decrease in metabolic activity with or without cotreatment with temozolomide (TMZ), the frontline chemotherapy for GBM. Most importantly, Gli1 PEI-SNAs impair the self-renewal capacity of GBM cells as indicated by a 30-40% reduction in the expression of stemness genes and further impair the formation of stem-like neurospheres. They also substantially improve neurosphere chemosensitivity as demonstrated by a 2-fold increase in the fraction of cells undergoing apoptosis in response to low doses of TMZ. These results underscore the potential for siRNA therapeutics targeting Gli1 to reduce GBM resistance to therapy and warrant further development of PEI-SNAs and Gli1-targeted therapies to alleviate drug resistance and recurrence for GBM patients.

Garcinol sensitizes breast cancer cells to Taxol through the suppression of caspase-3/iPLA2 and NF-κB/Twist1 signaling pathways in a mouse 4T1 breast tumor model

Breast cancer is a significant threat to women's health and has high incidence and mortality. Metastasis in breast cancer patients is a major cause of cancer deaths among women worldwide. Clinical experience suggests that patients with metastatic triple-negative breast cancer (TNBC) relapse quickly and often have chemotherapy resistance. Taxol (paclitaxel) is an effective chemotherapeutic agent for treating metastatic breast cancer, but Taxol at high doses can cause adverse effects and recurrent resistance. Thus, the selection of a synergistic combination therapy is recommended, which is safer and has a more significant response rate than monotherapy. In this study, our strategy is to combine a low dose of Taxol (5 mg kg^-1, i.p.) and garcinol (1 mg kg^-1, i.g.) to investigate the synergistic antitumor and anti-metastasis effects and to determine the underlying mechanisms of these effects in vivo. For the in vivo study, metastasis-specific mouse mammary carcinoma 4T1 cells were inoculated in Balb/c mice to establish an orthotopic primary tumor and spontaneous metastasis model. Tumor growth and metastases were monitored. The mechanisms of synergistic efficacies were evaluated at different signaling pathways, including proliferation, survival, and epithelial-mesenchymal transition (EMT)-regulated metastatic propensity. We demonstrated that garcinol combined with Taxol significantly increased the therapeutic efficacy when compared with either treatment alone. The synergistic antitumor and anti-metastasis effects were enhanced primarily through the induction of Taxol-stimulated G2/M phase arrest and the inhibition of caspase-3/cytosolic Ca²⁺-independent phospholipase A2 (iPLA₂) and nuclear factor-κB (NF-κB)/Twist-related protein 1 (Twist1) drive downstream events including tumor cell repopulation, survival, inflammation, angiogenesis, invasion, and EMT. Our current findings provide the first experimental evidence that a combination of a low dose of Taxol and garcinol is a promising therapeutic strategy for controlling advanced or metastatic breast cancer. Finally, our results also point to the possible role of NF-κB/Twist1 and caspase-3/iPLA₂ signaling pathways as biomarkers to predict the tumor response to treatment.

Sulforaphane-cysteine induces apoptosis by sustained activation of ERK1/2 and caspase 3 in human glioblastoma U373MG and U87MG cells

We previously demonstrated that sulforaphane (SFN) inhibited invasion via sustained activation of ERK1/2 in human glioblastoma cells. However, sulforaphane-cysteine (SFN-Cys), an analog of SFN, enriched in plasma with longer half-life, had more potentiality to induce apoptosis. Here we investigated the molecular mechanisms of SFN-Cys-induced apoptosis in human glioblastoma U373MG and U87MG cells. Cell viability assay showed that SFN-Cys inhibited cell viability in a dose-dependent manner. Cell morphology observation also showed SFN-Cys increased the phenotype of cell death in a dose-dependent manner. Furthermore, flow cytometry assay showed that SFN-Cys induced apoptosis significantly in a dose-dependent manner in both cell lines. Furthermore, western blot analysis demonstrated that SFN-Cys induced activation of ERK1/2 in a sustained manner and the activation contributed to upregulation of Bax/Bcl-2 ratio and cleaved caspase 3, and these results can be reversed by the ERK1/2 blocker PD98059. Our results showed that SFN-Cys induced cell apoptosis via sustained activation of ERK1/2 and the ERK1/2 mediated signaling pathways such as activation of caspase 3 and apoptosis-related proteins, thus indicating that SFN-Cys might be a more promising therapeutic agent versus SFN to resist glioblastoma cells, especially in Taxol-resistant cancer cells.

Co-delivery of VEGF and Bcl-2 dual-targeted siRNA polymer using a single nanoparticle for synergistic anti-cancer effects in vivo

Cancer is a multifactorial disease which involves complex genetic mutation and dysregulation. Combinatorial RNAi technology and concurrent multiple gene silencing are expected to provide advanced strategies for effective cancer therapy, but a safe and effective carrier system is a prerequisite to successful siRNA delivery in vivo. We previously developed an effective tumor-targeting siRNA delivery system for in vivo application. In response to the success of this development, herein we present a dual-gene targeted siRNA and its delivery system, to achieve synergistic effects in cancer therapy. Two different sequences of siRNA were chemically modified to be randomly copolymerized in a single backbone of siRNA polymer (Dual-poly-siRNA), and the resulting Dual-poly-siRNA was incorporated into tumor-homing glycol chitosan nanoparticles. Based on the stability in serum and delivery in a tumor-targeted manner, intravenously administered Dual-poly-siRNA carrying glycol chitosan nanoparticles (Dual-NP) demonstrated successful dual-gene silencing in tumors. Notably, co-delivery of VEGF and Bcl-2 targeting siRNA led to more effective cancer therapy for convenient application.

Plant derived substances with anti-cancer activity: from folklore to practice

Plants have had an essential role in the folklore of ancient cultures. In addition to the use as food and spices, plants have also been utilized as medicines for over 5000 years. It is estimated that 70-95% of the population in developing countries continues to use traditional medicines even today. A new trend, that involved the isolation of plant active compounds begun during the early nineteenth century. This trend led to the discovery of different active compounds that are derived from plants. In the last decades, more and more new materials derived from plants have been authorized and subscribed as medicines, including those with anti-cancer activity. Cancer is among the leading causes of morbidity and mortality worldwide. The number of new cases is expected to rise by about 70% over the next two decades. Thus, there is a real need for new efficient anti-cancer drugs with reduced side effects, and plants are a promising source for such entities. Here we focus on some plant-derived substances exhibiting anti-cancer and chemoprevention activity, their mode of action and bioavailability. These include paclitaxel, curcumin, and cannabinoids. In addition, development and use of their synthetic analogs, and those of strigolactones, are discussed. Also discussed are commercial considerations and future prospects for development of plant derived substances with anti-cancer activity.

Combination of BCL11A siRNA with vincristine increases the apoptosis of SUDHL6 cells

Background

B cell chronic lymphocytic leukemia/lymphoma 11 A (BCL11A) is associated with human B cell malignancy initiation. Our previous study has shown that downregulation of BCL11A mRNA by small interfering RNA (siRNA) is capable of inducing apoptosis in the SUDHL6 cell line. To further explore the effects of BCL11A siRNA on the enhanced cytotoxicity of a chemotherapeutic drug, we investigated the effects of BCL11A siRNA combined with vincristine (VCR) on SUDHL6 cell proliferation and apoptosis.

Methods

Chemically synthesized BCL11A siRNA was transfected into SUDHL6 cells using the HiPerFect Transfection Reagent in combination with VCR. Cell proliferation was measured by the CCK8 assay. The morphology of apoptotic cells was observed with Hoechst 33258 staining. The rate of cell apoptosis was determined by annexin V-fluorescein isothiocyanate/propidium iodide double staining using fluorescence-activated cell sorting (FACS) analysis.

Results

After BCL11A siRNA plus VCR treatment, cell proliferation was significantly decreased in comparison with VCR or BCL11A siRNA treatment alone and negative control siRNA plus VCR treatment (P <0.05). The apoptotic rate of BCL11A siRNA plus VCR treated cells was significantly increased compared with BCL11A siRNA and VCR treatment alone and negative control siRNA plus VCR treatment (P <0.05).

Conclusions

The combination of BCL11A siRNA and VCR increases apoptosis in SUDHL6 cells. Our study implies that BCL11A siRNA in combination with VCR may be a useful approach for improving effective treatment for B cell lymphoma.

Multifunctional hierarchically assembled nanostructures as complex stage-wise dual-delivery systems for coincidental yet differential trafficking of siRNA and paclitaxel

Development of multifunctional nanostructures that can be tuned to codeliver multiple drugs and diagnostic agents to diseased tissues is of great importance. Hierarchically assembled theranostic (HAT) nanostructures based on anionic cylindrical shell cross-linked nanoparticles and cationic shell cross-linked knedel-like nanoparticles (cSCKs) have recently been developed by our group to deliver siRNA intracellularly and to undergo radiolabeling. In the current study, paclitaxel, a hydrophobic anticancer drug, and siRNA have been successfully loaded into the cylindrical and spherical components of the hierarchical assemblies, respectively. Cytotoxicity, immunotoxicity, and intracellular delivery mechanism of the HAT nanostructures and their individual components have been investigated. Decoration of nanoparticles with F3-tumor homing peptide was shown to enhance the selective cellular uptake of the spherical particles, whereas the HAT nanoassemblies underwent an interesting disassembly process in contact with either OVCAR-3 or RAW 264.7 cell lines. The HAT nanostructures were found to "stick" to the cell membrane and "trigger" the release of spherical cSCKs templated onto their surfaces intracellularly, while retaining the cylindrical part on the cell surface. Combination of paclitaxel and cell-death siRNA (siRNA that induces cell death) into the HAT nanostructures resulted in greater reduction in cell viability than siRNA complexed with Lipofectamine and the assemblies loaded with the individual drugs. In addition, a shape-dependent immunotoxicity was observed for both spherical and cylindrical nanoparticles with the latter being highly immunotoxic. Supramolecular assembly of the two nanoparticles into the HAT nanostructures significantly reduced the immunotoxicity of both cSCKs and cylinders. HAT nanostructures decorated with targeting moieties, loaded with nucleic acids, hydrophobic drugs, radiolabels, and fluorophores, with control over their toxicity, immunotoxicity, and intracellular delivery might have great potential for biomedical delivery applications.

Knockdown of the Bcl-2 gene increases sensitivity to EGFR tyrosine kinase inhibitors in the H1975 lung cancer cell line harboring T790M mutation

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are being widely used as targeted therapy in non-small cell lung cancer (NSCLC), but most cases acquire drug-resistance in 9 months. However, the mechanisms of resistance are still not fully understood. Since it has been demonstrated that EGFR-TKI-mediated repression of downstream signaling cascades and apoptosis induction is a key mechanism through which EGFR-TKIs exert their cytotoxic effects, we reasoned that activation of downstream signaling pathways and changes in the expression of apoptosis-related proteins contribute to the acquired resistance to EGFR-TKIs. We analyzed the protein levels of p-Akt, Bcl-2, Bax between gefitinib-sensitive and gefitinib-resistant lung cancer cell lines and evaluated whether targeting the anti-apoptotic protein Bcl-2 induces cell apoptosis and further sensitizes resistant H1975 cells to gefitinib. The data showed that p-Akt was activated and accompanied by substantial Bcl-2 in the H1975 lung cancer cell line, whereas no evidence was observed in HCC827 cells. Using small interfering RNA (siRNA) to silence Bcl-2 in H1975 cells led to significant downregulation of Bcl-2 protein expression, decreased cell viability in vitro and induced intrinsic apoptosis confirmed by flow cytometry and PARP cleavage. In Bcl-2 siRNA-transfected cells, adding gefitinib further reduced the number of viable cells, induced apoptosis to a greater extent compared to either treatment alone. These preclinical data suggested that downregulation of Bcl-2 by RNAi in the gefitinib-resistant H1975 lung cancer cell line with T790M mutation enhanced the effects of gefitinib and may offer a novel therapeutic strategy for the treatment of NSCLC.

miR-138 overexpression is more powerful than hTERT knockdown to potentiate apigenin for apoptosis in neuroblastoma in vitro and in vivo

Decrease in expression of the tumor suppressor microRNA-138 (miR-138) correlates well with an increase in telomerase activity in many human cancers. The ability of almost all human cancer cells to grow indefinitely is dependent on presence of telomerase activity. The catalytic component of human telomerase reverse transcriptase (hTERT) regulates telomerase activity in most of the human cancers including malignant neuroblastoma. We observed an indirect increase in the expression of miR-138 after the transfection with hTERT short hairpin RNA (shRNA) plasmid in human malignant neuroblastoma SK-N-DZ and SK-N-BE2 cell lines. Transfection with hTERT shRNA plasmid followed by treatment with the flavonoid apigenin (APG) further increased expression of miR-138. Direct transfection with miR-138 mimic was more powerful than transfection with hTERT shRNA plasmid in potentiating efficacy of APG for decreasing cell viability and colony formation capability of both cell lines. Upregulation of miR-138 was also more effective than down regulation of hTERT in enhancing efficacy of APG for induction of apoptosis in malignant neuroblastoma cells in vitro and in vivo. We delineated that apoptosis occurred with induction of molecular components of the extrinsic and intrinsic pathways in SK-N-DZ and SK-N-BE2 cells both in vitro and in vivo. In conclusion, these results demonstrate that direct miR-138 overexpression is more powerful than hTERT down regulation in enhancing pro-apoptotic effect of APG for controlling growth of human malignant neuroblastoma in cell culture and animal models.

Sequential hTERT knockdown and apigenin treatment inhibited invasion and proliferation and induced apoptosis in human malignant neuroblastoma SK-N-DZ and SK-N-BE2 cells

Human telomerase reverse transcriptase (hTERT) plays a key role in conferring immortality to human malignant neuroblastomas. We first determined differential expression of hTERT in four human malignant neuroblastoma SH-SY5Y, SK-N-DZ, SK-N-BE2, and IMR-32 cell lines. We then used SK-N-DZ and SK-N-BE2 cell lines, which showed the highest expression of hTERT, to investigate the therapeutic effects of sequential hTERT knockdown and apigenin (APG) treatment. We performed cell invasion assay and studied alterations in expression of matrix metalloproteinases and cell cycle regulatory molecules after this combination therapy. We also investigated induction of apoptosis by using in situ Wright staining, Annexin V staining, and Western blotting. Sequential hTERT knockdown and APG treatment significantly downregulated expression of hTERT so as to cause over 90 % inhibition of cell invasion and 70 % induction of apoptosis in both SK-N-DZ and SK-N-BE2 cell lines. Western blotting demonstrated downregulation of the molecules involved in cell invasion and proliferation, but upregulation of the cell cycle inhibitor and apoptosis-inducing molecules. In conclusion, our current results clearly showed that sequential hTERT knockdown and APG treatment could be a promising therapeutic strategy for effective inhibition of invasion and proliferation and induction of apoptosis in hTERT overexpressing malignant neuroblastoma cells.

Nanoformulation of natural products for prevention and therapy of prostate cancer

There is a need for developing improved therapeutic options for the management of prostate cancer, able to inhibit proliferation of precancerous and malignant lesions and/or to improve the effectiveness of conventional chemopreventive and chemotherapeutic agents. In this perspective, application of nanotechnology based strategies for the delivery of natural compounds for effective management of the disease is being actively researched. Here, after highlighting the most promising natural compounds for chemoprevention and chemotherapy of prostate cancer, the state of the art nanotherapeutics and the recent proof-of-concept of "nanochemoprevention", as well as the clinical development of promising targeted nanoprototypes for use in the prostate cancer treatment are being discussed.

Synergistic anti-cancer mechanisms of curcumin and paclitaxel for growth inhibition of human brain tumor stem cells and LN18 and U138MG cells

Glioblastoma, the deadliest brain tumor in humans, responds poorly to conventional chemotherapeutic agents because of existence of highly chemoresistant human brain tumor stem cells (HBTSC). An effective therapeutic strategy is urgently needed to target HBTSC as well as other glioblastoma cells. We explored synergistic efficacy of a low dose of curcumin (CCM) and a low dose of paclitaxel (PTX) in HBTSC and human glioblastoma LN18 (p53 mutant and PTEN proficient) and U138MG (p53 mutant and PTEN mutant) cells. The highest expression of the cancer stem cell markers aldehyde dehydrogenase 1 (ALDH1) and CD133 occurred in HBTSC when compared with LN18 and U138MG cells. Combination of 20μM CCM and 10nM PTX worked synergistically and more effectively than either drug alone in decreasing viability in all cells. Combination of CCM and PTX was highly effective in inducing both morphological and biochemical features of apoptosis. Apoptosis required activation of caspase-8, cleavage of Bid to tBid, increase in Bax:Bcl-2 ratio, and mitochondrial release of cytochrome c, Smac, and apoptosis-inducing factor (AIF). Phosphorylation of Bcl-2 following combination therapy appeared to promote Bax homodimerization and mitochondrial release of pro-apoptotic factors into the cytosol. Increases in activities of cysteine proteases confirmed the completion of apoptotic process. Combination therapy inhibited invasion of cells, reduced expression of survival and proliferation factors and also angiogenic factors, and prevented HBTSC, LN18, and U138MG cells from promoting network formation. Collectively, the combination of CCM and PTX worked as a promising therapy for controlling the growth of HBTSC and other glioblastoma cells.

Impact of nanotechnology in cancer: emphasis on nanochemoprevention

Since its advent in the field of cancer, nanotechnology has provided researchers with expertise to explore new avenues for diagnosis, prevention, and treatment of the disease. Utilization of nanotechnology has enabled the development of devices in nanometer (nm) sizes which could be designed to encapsulate useful agents that have shown excellent results but otherwise are generally toxic due to the doses intended for extended use. In addition, examples are also available where these devices are easily conjugated with several purposeful moieties for better localization and targeted delivery. We introduced a novel concept in which nanotechnology was utilized for enhancing the outcome of chemoprevention. This idea, which we termed as “nanochemoprevention,” was subsequently exploited by several laboratories worldwide and has now become an advancing field in chemoprevention research. This review examines some of the up and coming applications of nanotechnology for cancer detection, imaging, treatment, and prevention. Further, we detail the current and future utilization of nanochemoprevention for prevention and treatment of cancer.

Selective aurora kinase inhibitors identified using a taxol-induced checkpoint sensitivity screen

The members of the Aurora kinase family play critical roles in the regulation of the cell cycle and mitotic spindle assembly and have been intensively investigated as potential targets for a new class of anticancer drugs. We describe a new highly potent and selective class of Aurora kinase inhibitors discovered using a phenotypic cellular screen. Optimized inhibitors display many of the hallmarks of Aurora inhibition including endoreduplication, polyploidy, and loss of cell viability in cancer cells. Structure-activity relationships with respect to kinome-wide selectivity and guided by an Aurora B co-crystal structure resulted in the identification of key selectivity determinants and discovery of a subseries with selectivity toward Aurora A. A direct comparison of biochemical and cellular profiles with respect to published Aurora inhibitors including VX-680, AZD1152, MLN8054, and a pyrimidine-based compound from Genentech demonstrates that compounds 1 and 3 will become valuable additional pharmacological probes of Aurora-dependent functions.

Drug resistance in glioblastoma: a mini review

Glioblastoma multiforme (GBM) is recognized as the most common and lethal form of central nervous system cancer. Currently used surgical techniques, chemotherapeutic agents, and radiotherapy strategies have done very little in extending the life expectancies of patients diagnosed with GBM. The difficulty in treating this malignant disease lies both in its inherent complexity and numerous mechanisms of drug resistance. In this review, we summarize several of the primary mechanisms of drug resistance. We reviewed available published literature in the English language regarding drug resistance in glioblastoma. The reasons for drug resistance in glioblastoma include drug efflux, hypoxic areas of tumor cells, cancer stem cells, DNA damage repair, and miRNAs. Many potential therapies target these mechanisms, including a series of investigated alternative and plant-derived agents. Future research and clinical trials in glioblastoma patients should pursue combination of therapies to help combat drug resistance. The emerging new data on the potential of plant-derived therapeutics should also be closely considered and further investigated.

Nanoparticle delivery of natural products in the prevention and treatment of cancers: current status and future prospects

The advent of nanotechnology has had a revolutionary impact on many aspects of 21^st century life. Nanotechnology has provided an opportunity to explore new avenues that conventional technologies have been unable to make an impact on for diagnosis, prevention, and therapy of different diseases, and of cancer in particular. Entities in nanometer sizes are excellent platforms to incorporate various drugs or active materials that can be delivered effectively to the desired action site without compromising the activity of the incorporated drug or material. In particular, nanotechnology entities can be used to deliver conventional natural products that have poor solubility or a short half life. Conventional natural products used with entities in nanometer sizes enable us to solve many of the inherent problems (stability, solubility, toxicity) associated with natural products, and also provide a platform for targeted delivery to tumor sites. We recently introduced the novel concept of using nanotechnology for enhancing the outcome of chemoprevention, which we called ‘nanochemoprevention’. This idea was subsequently exploited by several laboratories worldwide and has now become an advancing field in chemoprevention research. This review examines some of the applications of nanotechnology for cancer prevention and therapy using natural products.

Survivin knockdown and concurrent 4-HPR treatment controlled human glioblastoma in vitro and in vivo

Survivin is highly expressed in most cancers, including glioblastoma, and it plays a significant role in inhibiting apoptosis and promoting tumor growth. Treatment of cancer cells with N-(4-hydroxyphenyl) retinamide (4-HPR) induces apoptosis through destabilization of mitochondrial membrane and activation of caspase-mediated apoptotic pathways. We studied the efficacy of a combination of survivin knockdown and 4-HPR treatment to induce apoptosis and inhibit invasion, angiogenesis, and growth of human glioblastomas in vitro and in vivo. Using a plasmid encoding survivin shRNA, we downregulated survivin in glioblastoma U251MG and U118MG cells and simultaneously treated with 1 µM 4-HPR for 48 hours. Cells following treatments were subjected to the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and invasion assays. In vivo angiogenesis and tumor regression studies were performed in nude mice. TUNEL assay demonstrated apoptosis in more than 80% of cells after survivin knockdown and 4-HPR treatment. Matrigel invasion assays demonstrated marked decreases in tumor cell invasion. In vivo angiogenesis studies depicted a remarkable inhibition of neovascularization due to the knockdown of survivin and 4-HPR treatment. Imaging of intracerebral tumorigenesis and longitudinal studies on subcutaneous solid tumor formation showed dramatic decreases in tumorigenesis and solid tumor progression, respectively, after treatment with the combination. Studies to elucidate the molecular mechanisms of the inhibition of angiogenesis and tumor regression demonstrated marked decreases in proliferating cell nuclear antigen, metalloproteinase-9, vascular endothelial growth factor, basic fibroblast growth factor, and CD31 in solid tumors. Our data demonstrated that survivin knockdown and concurrent 4-HPR treatment could be a novel therapeutic strategy for controlling growth of human glioblastomas.

Knockdown of hTERT and concurrent treatment with interferon-gamma inhibited proliferation and invasion of human glioblastoma cell lines

Human telomerase reverse transcriptase (hTERT) is the catalytic component of telomerase that facilitates tumor cell invasion and proliferation. Telomerase and hTERT are remarkably upregulated in majority of cancers including glioblastoma. Interferon-gamma (IFN-gamma) modulates several cellular activities including cell cycle and multiplication through transcriptional regulation. The present investigation was designed to unravel the molecular mechanisms of the inhibition of cell proliferation, migration, and invasion of human glioblastoma SNB-19 and LN-18 cell lines after knockdown of hTERT using a plasmid vector based siRNA and concurrent treatment with IFN-gamma. We observed more than 80% inhibition of cell proliferation, migration, and invasion of both cell lines after the treatment with combination of hTERT siRNA and IFN-gamma. Our studies also showed accumulation of apoptotic cells in subG1 phase and an increase in cell population in G0/G1 with a reduction in G2/M phase indicating cell cycle arrest in G0/G1 phase for apoptosis. Semiquantitative and real-time RT-PCR analyses demonstrated significant downregulation of c-Myc and upregulation of p21 Waf1 and p27 Kip1. Western blotting confirmed the downregulation of the molecules involved in cell proliferation, migration, and invasion and also showed upregulation of cell cycle inhibitors. In conclusion, our study demonstrated that knockdown of hTERT and concurrent treatment with IFN-gamma effectively inhibited cell proliferation, migration, and invasion in glioblastoma cells through downregulation of the molecules involved in these processes and cell cycle inhibition. Therefore, the combination of hTERT siRNA and IFN-gamma offers a potential therapeutic strategy for controlling growth of human glioblastoma cells.

Combination of hTERT knockdown and IFN-gamma treatment inhibited angiogenesis and tumor progression in glioblastoma

PURPOSE

The limitless invasive and proliferative capacities of tumor cells are associated with telomerase and expression of its catalytic component, human telomerase reverse transcriptase (hTERT). IFN-gamma modulates several cellular activities, including signaling pathways and cell cycle, through transcriptional regulation.

EXPERIMENTAL DESIGN

Using a recombinant plasmid with hTERT siRNA cDNA, we downregulated hTERT during IFN-gamma treatment in human glioblastoma SNB-19 and LN-18 cell lines and examined whether such a combination could inhibit angiogenesis and tumor growth in nude mice. In vitro angiogenesis assay was done using coculture of tumor cells with human microvascular endothelial cells. In vivo angiogenesis assay was done using diffusion chambers under the dorsal skin of nude mice. In vivo imaging of intracerebral tumorigenesis and longitudinal solid tumor development studies were conducted in nude mice.

RESULTS

In vitro and in vivo angiogenesis assays showed inhibition of capillary-like network formation of microvascular endothelial cells and neovascularization under dorsal skin of nude mice, respectively. We observed inhibition of intracerebral tumorigenesis and s.c. solid tumor formation in nude mice after treatment with combination of hTERT siRNA and IFN-gamma. Western blotting of solid tumor samples showed significant downregulation of the molecules that regulate cell invasion, angiogenesis, and tumor progression.

CONCLUSIONS

Our study showed that the combination of hTERT siRNA and IFN-gamma effectively inhibited angiogenesis and tumor progression through the downregulation of molecules involved in these processes. Therefore, the combination of hTERT siRNA and IFN-gamma is a promising therapeutic strategy for controlling the growth of human glioblastoma.