A novel antisense oligonucleotide inhibiting several antiapoptotic Bcl-2 family members induces apoptosis and enhances chemosensitivity in androgen-independent human prostate cancer PC3 cells

Theranostic DNA nanostructure based on phenotype-specific activation of antisense oligonucleotides

Antisense oligonucleotide (ASO) is a powerful agent for gene therapy, designed to form complementary pairs with specific mRNA to inhibit gene expression. However, low specificity limits its potential. To overcome this challenge, we developed a Y-shape DNA nanostructure that enhances the specificity in ASO-based treatment by introducing a detection trigger. The design incorporates the phenotype-specific miR21 activation and the sequential release of Bcl2 ASO. As a result, our Y-shape DNA nanostructure downregulates >50 % Bcl2 mRNA expression and induces >60 % cell death in breast cancer cells. Meanwhile, this approach shows no obvious damage to the non-cancerous cells, indicating the therapeutic potential as a theranostics agent in precision medicine with the combination of biomarker sensing and treatment. Overall, our Y-shape DNA nanostructure serves as a promising strategy providing potential in customized conformation design with specific target sequences in gene therapy.

Making Sense of Antisense Oligonucleotide Therapeutics Targeting Bcl-2

The B-cell lymphoma 2 (Bcl-2) family, comprised of pro- and anti-apoptotic proteins, regulates the delicate balance between programmed cell death and cell survival. The Bcl-2 family is essential in the maintenance of tissue homeostasis, but also a key culprit in tumorigenesis. Anti-apoptotic Bcl-2, the founding member of this family, was discovered due to its dysregulated expression in non-Hodgkin’s lymphoma. Bcl-2 is a central protagonist in a wide range of human cancers, promoting cell survival, angiogenesis and chemotherapy resistance; this has prompted the development of Bcl-2-targeting drugs. Antisense oligonucleotides (ASO) are highly specific nucleic acid polymers used to modulate target gene expression. Over the past 25 years several Bcl-2 ASO have been developed in preclinical studies and explored in clinical trials. This review will describe the history and development of Bcl-2-targeted ASO; from initial attempts, optimizations, clinical trials undertaken and the promising candidates at hand.

Induction of Apoptosis in MDA-MB-231 Cells Treated with the Methanol Extract of Lichen Physconia hokkaidensis

Physconia hokkaidensis methanol extract (PHE) was studied to identify anticancer effects and reveal its mechanism of action by an analysis of cytotoxicity, cell cycles, and apoptosis biomarkers. PHE showed strong cytotoxicity in various cancer cells, including HL-60, HeLa, A549, Hep G2, AGS, MDA-MB-231, and MCF-7. Of these cell lines, the growth of MDA-MB-231 was concentration-dependently suppressed by PHE, but MCF-7 was not affected. MDA-MB-231 cells, triple-negative breast cancer (TNBC) cells, do not express estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER-2), whereas MCF-7 cells are ER-positive, PR-positive, and HER-2-negative breast cancer cells. The number of cells in sub-G1 phase was increased after 24 h of treatment, and annexin V/PI staining showed that the population size of apoptotic cells was increased by prolonged exposure to PHE. Moreover, PHE treatment downregulated the transcriptional levels of Bcl-2, AMPK, and p-Akt, whereas it significantly upregulated the levels of cleaved caspase-3, cleaved caspase-9, and cleaved-PARP. In conclusion, it was confirmed that the PHE exhibited selective cytotoxicity toward MDA-MB-231, not toward MCF-7, and its cytotoxic activity is based on induction of apoptosis.

Nucleic acids therapeutics using PolyPurine Reverse Hoogsteen hairpins

PolyPurine Reverse Hoogsteen hairpins (PPRHs) are DNA hairpins formed by intramolecular reverse Hoogsteen bonds which can bind to polypyrimidine stretches in dsDNA by Watson:Crick bonds, thus forming a triplex and displacing the fourth strand of the DNA complex. PPRHs were first described as a gene silencing tool in vitro for DHFR, telomerase and survivin genes. Then, the effect of PPRHs directed against the survivin gene was also determined in vivo using a xenograft model of prostate cancer cells (PC3). Since then, the ability of PPRHs to inhibit gene expression has been explored in other genes involved in cancer (BCL-2, mTOR, topoisomerase, C-MYC and MDM2), in immunotherapy (SIRPα/CD47 and PD-1/PD-L1 tandem) or in replication stress (WEE1 and CHK1). Furthermore, PPRHs have the ability to target the complementary strand of a G-quadruplex motif as a regulatory element of the TYMS gene. PPRHs have also the potential to correct point mutations in the DNA as shown in two collections of CHO cell lines bearing mutations in either the dhfr or aprt loci. Finally, based on the capability of PPRHs to form triplexes, they have been incorporated as probes in biosensors for the determination of the DNA methylation status of PAX-5 in cancer and the detection of mtLSU rRNA for the diagnosis of Pneumocystis jirovecii. Of note, PPRHs have high stability and do not present immunogenicity, hepatotoxicity or nephrotoxicity in vitro. Overall, PPRHs constitute a new economical biotechnological tool with multiple biomedical applications.

Endomorphin-2 Analog Inhibits the Growth of DLD-1 and RKO Human Colon Cancer Cells by Inducing Cell Apoptosis

Background

In developed countries, colon cancer is a leading cause of cancer-associated mortality. Dietary changes have resulted in an increased incidence of colon cancer in Asia. This study aimed to investigate the effects of the structural analog of endomorphin-2 (H-Tyr-Pro-Phe-Phe-NH₂) on human colon cancer cells in vitro.

Material/Methods

Human DLD-1 and RKO colon cancer cells and CCD-18Co normal human colonic fibroblasts were treated with increasing doses of the structural analog of endomorphin-2. Cells underwent the MTT assay, fluorescence confocal flow cytometry, and Hoechst 33258 staining to investigate cell proliferation, the cell cycle, and apoptosis. Western blot was used to measure the expression levels of poly(ADP-ribose) polymerase-1 (PARP-1), cytochrome c, caspase-3, and caspase-9. The 2′,7′-dichlorofluorescein diacetate (DCFH-DA) fluorescence method measured reactive oxygen species (ROS).

Results

Cell proliferation of DLD-1 and RKO cells was inhibited by the endomorphin-2 analog in a dose-dependent manner, and a 100 μM dose reduced DLD-1 and RKO cell proliferation by 28% and 23%, respectively, at 72 h. Endomorphin-2 analog induced cell apoptosis and the generation of ROS, activated caspase-3 and caspase-9, and increased the levels of p53 and cytochrome c release, and down-regulated of Akt activation in DLD-1 and RKO cells in a dose-dependent manner. Treatment of the DLD-1 and RKO cells with the endomorphin-2 analog increased the expression of Bax and reduced the expression of Bcl-2.

Conclusions

Endomorphin-2 analog inhibited colon cancer cell proliferation, activated apoptosis, and down-regulated Akt phosphorylation of human DLD-1 and RKO colon cancer cells in vitro in a dose-dependent manner.

Topological properties and in vitro identification of essential nodes of the Paclitaxel and Vincristine interactomes in PC-3 cells

Background

Microtubule-targeting agents (MTAs) disrupt microtubule dynamics, thereby inducing apoptosis via mitochondrial pathway activation through the modulation in the expression of the Bcl-2 family.

Methods

To describe topological features of the MTAs networks associated to intrinsic apoptosis induction in p53-null prostate cancer cells, we predicted and compared the interactomes and topological properties of Paclitaxel and Vincristine, and thus, the essential nodes corresponding with the pro- and anti-apoptotic proteins and their kinetics were subjected to experimental analysis in PC-3 cell line.

Results

The essential nodes of the apoptotic pathways, TP53, and CASP3, were identified in both, Paclitaxel and Vincristine networks, but the intrinsic pathway markers BCL2, BAX, and BCL2L1 were identified as hub nodes only in the Paclitaxel network. An in vitro analysis demonstrated an increase in BimEL and the cleaved-caspase-3 proteins in PC-3 cells exposed to both treatments. Immunoprecipitation analysis showed that treatments induced the releasing of Bax from the anti-apoptotic complex with Bcl-2 protein and the role of BimEL as a de-repressor from sequestering complexes, in addition, new protein complexes were identified between BimEL or Bcl-2 and cleaved-caspase-3, contributing data to the Vincristine network for p53-null cells in response to MTAs.

Conclusion

The differences in sensitivities, protein profiles, and protein complex kinetics observed between the drugs confirmed that the selectivity and stimulation of the apoptotic system vary depending on the cell's genotype, the drug used and its exposure period.

Inhibition of Colon Cancer Cell Growth by Imidazole Through Activation of Apoptotic Pathway

Background

This study aimed to investigate the inhibitory effect of imidazole on colon cancer cell proliferation and understand the mechanism involved.

Material/Methods

MTT assay and flow cytometry using Hoechst 33258 staining were used to assess cell proliferation and morphology, respectively. Changes in protein expression was determined by western blotting assay. The reactive oxygen species (ROS) production in DLD-1 cells was analyzed by flow cytometry using DCFH-DA (2′,7′-dichlorofluorescein diacetate) stain.

Results

DLD-1 and HCT-116 cell viability was suppressed by imidazole in a concentration-based manner. At the concentration of 36 μM, imidazole reduced DLD-1 and HCT-116 cell viability to 22% and 28%, respectively. Treatment with imidazole led to chromatin material condensation, detaching of cells, and apoptotic nuclei. In imidazole treated cells, the G1/G0 phase cell proportion increased, whereas in the S and G2/M phases the cell proportion decreased. Imidazole treatment of DLD-1 cells markedly promoted activation of caspase-3, caspase-8, and caspase-9. The level of cleaved PARP1 was also upregulated in DLD-1 cells with imidazole treatment. Treatment of DLD-1 cells with imidazole suppressed Bcl-2 and promoted Bax, p53, and cytc expression. The Akt activation was suppressed by imidazole treatment in DLD-1 cells. ROS generation in DLD-1 cells was enhanced markedly by treatment with imidazole.

Conclusions

The present study demonstrated that imidazole inhibited colon cancer cell viability through activation of apoptosis and cell cycle arrest by increasing the generation of ROS, caspase activation, and apoptotic protein expression. Therefore, imidazole can act as a therapeutic molecule for the treatment of colon cancer.

Two-in-One Chemogene Assembled from Drug-Integrated Antisense Oligonucleotides To Reverse Chemoresistance

Combinatorial chemo and gene therapy provides a promising way to cure drug-resistant cancer, since the codelivered functional nucleic acids can regulate drug resistance genes, thus restoring sensitivity of the cells to chemotherapeutics. However, the dramatic chemical and physical differences between chemotherapeutics and nucleic acids greatly hinder the design and construction of an ideal drug delivery system (DDS) to achieve synergistic antitumor effects. Herein, we report a novel approach to synthesize a nanosized DDS using drug-integrated DNA with antisense sequences (termed "chemogene") to treat drug-resistant cancer. As a proof of concept, floxuridine (F), a typical nucleoside analog antitumor drug, was incorporated in the antisense sequence in the place of thymine (T) based on their structural similarity. After conjugation with polycaprolactone, a spherical nucleic acid (SNA)-like two-in-one chemogene can be self-assembled, which possesses the capabilities of rapid cell entry without the need for a transfection agent, efficient downregulation of drug resistance genes, and chronic release of chemotherapeutics for treating the drug-resistant tumors in both subcutaneous and orthotopic liver transplantation mouse models.

Overexpression of microRNA-183 promotes apoptosis of substantia nigra neurons via the inhibition of OSMR in a mouse model of Parkinson's disease

The present study aimed to investigate the effect of microRNA-183 (miR-183) on substantia nigra neurons by targeting oncostatin M receptor (OSMR) in a mouse model of Parkinson’s disease (PD). The positive expression rates of OSMR and the apoptosis of substantia nigra neurons were detected by immunohistochemistry and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling, respectively. Substantia nigra neurons in normal and PD mice were cultured in vitro. The association between miR-183 and OSMR was verified using a dual luciferase reporter gene assay. The expression of miR-183 and the phosphoinositide 3-kinase-Akt signaling pathway-associated genes were detected by reverse transcription-quantitative polymerase chain reaction and western blot analysis, respectively. Cell apoptosis was detected by flow cytometry. OSMR is the target gene of miR-183. The number of OSMR-positive cells and the apoptotic rate of substantia nigra neurons were increased in the PD group. Neurons transfected with miR-183 mimic exhibited elevated expression levels of miR-183, B-cell lymphoma 2 (Bcl-2)-associated X protein (Bax) and caspase-9 and increased apoptotic rate, and reduced expression levels of OSMR, Akt, phosphorylated (p-)Akt, glycogen synthase kinase-3 (GSK-3β), p-GSK-3β, Bcl-2, insulin-like growth factor 1 (IGF-1), mammalian target of rapamycin (mTOR) and p-mTOR. The miR-183 inhibitor decreased the expression levels of miR-183, Bax and caspase-9 and the apoptotic rate; however, increased the expression of OSMR, Akt, p-Akt, GSK-3β, p-GSK-3β, Bcl-2, IGF-1, mTOR and p-mTOR. The results of the present study provide evidence that the overexpression of miR-183 promotes the apoptosis of substantia nigra neurons by inhibiting the expression of OSMR.

PTBP1 enhances miR-101-guided AGO2 targeting to MCL1 and promotes miR-101-induced apoptosis

Myeloid cell leukemia 1 (MCL1) is a key anti-apoptotic protein belonging to the BCL-2 protein family. To preserve normal cellular homeostasis, cells must maintain strict control over MCL1 expression. Overexpression of MCL1 has been identified as a key contributor to tumorigenesis, and further enables resistance to a number of anti-cancer chemotherapies. Thus, there is an ongoing interest to develop selective MCL1 inhibitors. In order to better target MCL1, it is essential to understand the molecular mechanisms that regulate MCL1 expression in cells. While MCL1 expression is tightly controlled by multiple mechanisms, the post-transcriptional regulation of MCL1 mRNA is poorly studied. Our previous work identified that polypyrimidine tract binding protein 1 (PTBP1) binds to MCL1 mRNA and represses MCL1 expression by destabilizing MCL1 mRNA. In this report, we show that PTBP1 modulates MCL1 expression by regulating the microRNA (miRNA) direction of the miRNA-induced silencing complex (miRISC) to MCL1. We demonstrate that PTBP1 enhances miR-101-guided AGO2 interaction with MCL1, thereby regulating miR-101-induced apoptosis and clonogenic cell survival inhibition in cells. Taken together, not only do these studies expand our understanding on the regulation of MCL1, they also demonstrate that PTBP1 and miRNAs can function cooperatively on a shared target mRNA.

'Borono-lectin' based engineering as a versatile platform for biomedical applications

Boronic acids are well known for their ability to reversibly interact with the diol groups, a common motif of biomolecules including sugars and ribose. Due to their ability to interact with carbohydrates, they can be regarded as synthetic mimics of lectins, termed 'borono-lectins'. The borono-lectins can be tailored to elicit a broad profile of binding strength and specificity. This special property has been translated into many creative biomedical applications in a way interactive with biology. This review provides a brief overview of recent efforts of polymeric materials-based engineering taking advantage of such virtue of 'borono-lectins' chemistry, related to the field of biomaterials and drug delivery applications.

HDAC inhibitor PAC-320 induces G2/M cell cycle arrest and apoptosis in human prostate cancer

HDAC inhibitors (HDACis) have been demonstrated with profound antiproliferative activities in various tumor types. Previously, we screened several polyoxometalate HDACis based on our p21 luciferase promoter system and demonstrated that such HDACis have antitumor activity. Here, we further investigate the antitumor mechanism of PAC-320, a compound among the polyoxometalates, in human prostate cancer. We demonstrate that PAC-320 is a broad-spectrum HDACi and could inhibit growth of prostate cancer cells in vitro and in vivo. Furthermore, we find that PAC-320 induces cell cycle arrest at G2/M phase and apoptosis. Mechanically, PAC-320 induced cell cycle arrest is associated with an increase of p21 and decrease of cyclin A and cyclin B1, while PAC-320 induced apoptosis is mediated through mitochondria apoptotic pathway and is closely associated with increase of BH3-only proteins Noxa and Hrk. Meanwhile, we demonstrate that p38 MAPK pathway is involved in PAC-320 induced antiproliferative activities in prostate cancer. Taken together, our data indicates that PAC-320 has potent prostate cancer inhibitory activity in vitro and in vivo, which is mediated by G2/M cell cycle arrest and apoptosis.

Embelin-Induced Apoptosis of Human Prostate Cancer Cells Is Mediated through Modulation of Akt and β-Catenin Signaling

There is increasing evidence that embelin, an active component of Embelia ribes, induces apoptosis in human cancer cells, but the detailed mechanisms are still unclear. Here, we have investigated the effect of embelin on the growth of human prostate cancer cells. Embelin strongly inhibited cell growth especially in human prostate cancer cell lines, including PC3, DU145, LNCaP-LN3 and normal prostate epithelial cell, RWPE-1 compared to breast cancer (MDA-MB-231, MCF-7, and T47D), hepatoma (HepG2, Hep3B, and HuH-7), or choriocarcinoma (JEG-3). We observed that embelin induced apoptosis of PC3 cells in a time-dependent manner correlated with decreased expression of Bcl-2, Bcl-xL, and Mcl-1, increased translocation of Bax into mitochondria, and a reduction in the mitochondrial membrane potential. Furthermore, embelin induced voltage-dependent anion channel (VDAC) 1 expression and oligomerization, which may promote cytochrome c and AIF release. Because embelin was able to inhibit Akt activation and cyclooxygenase-2 expression, the effects on Wnt/ β-catenin signaling were determined. Embelin activated glycogen synthase kinase (GSK)-3β by preventing phosphorylation and suppressed β-catenin expression. Attenuation of β-catenin-mediated TCF transcriptional activity and gene transcription, such as cyclin D1, c-myc, and matrix metalloproteinase (MMP)-7, were shown in embelin-treated cells. The changes in β-catenin levels in response to embelin were blocked by lithium chloride, a GSK-3 inhibitor, indicating that embelin may decrease β-catenin expression via GSK-3β activation. Furthermore, exposure of PC3 cells to embelin resulted in a significant decrease in cell migration and invasion. In conclusion, these findings suggest that inhibition of Akt signaling and activation of GSK-3β partially contributes to the pro-apoptotic effect of embelin in prostate cancer cells.

Harnessing the apoptotic programs in cancer stem-like cells

Elimination of malignant cells is an unmet challenge for most human cancer types even with therapies targeting specific driver mutations. Therefore, a multi-pronged strategy to alter cancer cell biology on multiple levels is increasingly recognized as essential for cancer cure. One such aspect of cancer cell biology is the relative apoptosis resistance of tumor-initiating cells. Here, we provide an overview of the mechanisms affecting the apoptotic process in tumor cells emphasizing the differences in the tumor-initiating or stem-like cells of cancer. Further, we summarize efforts to exploit these differences to design therapies targeting that important cancer cell population.

Design and Synthesis of Antitumor Heck-Coupled Sclareol Analogues: Modulation of BH3 Family Members by SS-12 in Autophagy and Apoptotic Cell Death

Sclareol, a promising anticancer labdane diterpene, was isolated from Salvia sclarea. Keeping the basic stereochemistry-rich framework of the molecule intact, a method for the synthesis of novel sclareol analogues was designed using palladium(II)-catalyzed oxidative Heck coupling reaction in order to study their structure-activity relationship. Both sclareol and its derivatives showed an interesting cytotoxicity profile, with 15-(4-fluorophenyl)sclareol (SS-12) as the most potent analogue, having IC50 = 0.082 μM against PC-3 cells. It was found that SS-12 commonly interacts with Bcl-2 and Beclin 1 BH3 domain proteins and enhances autophagic flux by modulating autophagy-related proteins. Moreover, inhibition of autophagy by autophagy inhibitors protected against SS-12-induced apoptosis. Finally, SS-12 effectively suppressed tumor growth in vivo in Ehrlich's ascitic and solid Sarcoma-180 mouse models.

Solena amplexicaulis induces cell cycle arrest, apoptosis and inhibits angiogenesis in hepatocarcinoma cells and HUVECs

Solena amplexicaulis (Lam.) Gandhi (SA) has been used as a traditional medicine for the treatment of dysentery, multiple abscess, gastralgia, urethritis, and eczema in the minority area of China. This study was aimed to examine the cell proliferation inhibitory activity of the SA extract (SACE) and its mechanism of action in human hepatoma cell line (HepG2) and evaluate its anti-angiogenesis activity in human umbilical vein endothelial cell line (HUVEC). SACE could inhibit the growth of HepG2 cells in a dose- and time-dependent manner. FCM analysis showed that SACE could induce G2/M phase arrest, cell apoptosis, the mitochondrial membrane potential loss (ΔΨm) and increase the production of intracellular ROS of HepG2 cells. After treatment with SACE, topical morphological changes of apoptotic body formation, obvious increase of apoptosis-related protein expressions, such as Bax, cytochrome c, caspase-3, PARP-1, and decrease of Bcl-2, procaspase-9 protein expressions were observed at the same time. Moreover, SACE caused the significant inhibition of endothelial cell migration and tube formation in HUVEC cells. The results suggested that SACE could act as an angiogenesis inhibitor and induce cell apoptosis via a caspase-dependent mitochondrial pathway. Therefore, SACE could be a potent candidate for the prevention and treatment of liver cancer.

MLN2238 synergizes BH3 mimetic ABT-263 in castration-resistant prostate cancer cells by induction of NOXA

Patients undergoing androgen blockade therapy develop castration-resistant prostate cancer (CRPC), which is associated with Bcl-2 upregulation and results in disease progression and death. In recent years, promising therapeutic agents, such as the BH3-only mimetic ABT-263 and proteasome inhibitors, have been developed and widely evaluated against a broad spectrum of cancer types, including prostate cancer, alone or in combination with other chemotherapeutic agents. In this study, the antitumor efficacy of ABT-263 and MLN2238 were evaluated as single agents and in combination in four CRPC cell lines: PC3, C4-2B, C4-2, and DU145. The viability of the treated cells and markers of apoptosis were assayed. Protein-protein interactions were analyzed by co-immunoprecipitation in drug-treated cells. Lentivirus-mediated short hairpin RNA was used to knockdown Bax, Mcl-1, and NOXA expressions. We found that ABT-263 and MLN2238 alone exhibited a mild cytotoxicity, and in combination, they elicited a synergistic cytotoxic effect in CRPC cells. The cell apoptosis induced by the combination drug treatment was evidenced by enhanced caspase-3 and Poly (ADP-ribose) polymerase (PARP) cleavage, and annexin-V-positive staining was significantly depleted by Bax knockdown. MLN2238 treatment upregulated NOXA and Mcl-1 expression, leading NOXA/Mcl-1 complexes to disassociate Bak from its complexes with Mcl-1 and enhancing ABT263-triggered Bax activation. NOXA knockdown by short hairpin RNA significantly attenuated the cytotoxicity of ABT-263 and MLN2238 co-administration. In conclusion, MLN2238 and ABT-263 synergistically triggered apoptosis in CRPC cells by upregulating NOXA and activating Bax, indicating a promising therapeutic strategy for the treatment of CRPC.

Molecular mechanism underlying hesperetin-induced apoptosis by in silico analysis and in prostate cancer PC-3 cells

AIM

To investigate the molecular mechanisms underlying triggering of apoptosis by hesperetin using in silico and in vitro methods.

METHODS

The mechanism of binding of hesperetin with NF-?B and other apoptotic proteins like BAX, BAD, BCL2 and BCLXL was analysed in silico using Schrodinger suite 2009. In vitro studies were also carried out to evaluate the potency of hesperetin in inducing apoptosis using the human prostate cancer PC-3 cell line.

RESULTS

Hesperetin was found to exhibit high-affinity binding resulting from greater intermolecular forces between the ligand and its receptor NF-?B (-7.48 Glide score). In vitro analysis using MTT assay confirmed that hesperetin reduced cell proliferation (IC50 values of 90 and 40μM at 24 and 48h respectively) in PC-3 cells. Hesperetin also downregulated expression of the anti-apoptotic gene BCLXL at both mRNA and protein levels and increased the expression of pro-apoptotic genes like BAD at mRNA level and BAX at mRNA as well as protein levels.

CONCLUSION

The results suggest that hesperetin can induce apoptosis by inhibiting NF-?B.

Reversing multidrug resistance in Caco-2 by silencing MDR1, MRP1, MRP2, and BCL-2/BCL-xL using liposomal antisense oligonucleotides

Multidrug resistance (MDR) is a major impediment to chemotherapy. In the present study, we designed antisense oligonucleotides (ASOs) against MDR1, MDR-associated protein (MRP)1, MRP2, and/or BCL-2/BCL-xL to reverse MDR transporters and induce apoptosis, respectively. The cationic liposomes (100 nm) composed of N-[1-(2,3-dioleyloxy)propyl]-n,n,n-trimethylammonium chloride and dioleoyl phosphotidylethanolamine core surrounded by a polyethylene glycol (PEG) shell were prepared to carry ASOs and/or epirubicin, an antineoplastic agent. We aimed to simultaneously suppress efflux pumps, provoke apoptosis, and enhance the chemosensitivity of human colon adenocarcinoma Caco-2 cells to epirubicin. We evaluated encapsulation efficiency, particle size, cytotoxicity, intracellular accumulation, mRNA levels, cell cycle distribution, and caspase activity of these formulations. We found that PEGylated liposomal ASOs significantly reduced Caco-2 cell viability and thus intensified epirubicin-mediated apoptosis. These formulations also decreased the MDR1 promoter activity levels and enhanced the intracellular retention of epirubicin in Caco-2 cells. Epirubicin and ASOs in PEGylated liposomes remarkably decreased mRNA expression levels of human MDR1, MRP1, MRP2, and BCL-2. The combined treatments all significantly increased the mRNA expressions of p53 and BAX, and activity levels of caspase-3, -8, and -9. The formulation of epirubicin and ASOs targeting both pump resistance of MDR1, MRP1, and MRP2 and nonpump resistance of BCL-2/BCL-xL demonstrated more superior effect to all the other formulations used in this study. Our results provide a novel insight into the mechanisms by which PEGylated liposomal ASOs against both resistance types act as activators to epirubicin-induced apoptosis through suppressing MDR1, MRP1, and MRP2, as well as triggering intrinsic mitochondrial and extrinsic death receptor pathways. The complicated regulation of MDR highlights the necessity for a multifunctional approach using an effective delivery system, such as PEGylated liposomes, to carry epirubicin and ASOs as a potent nanomedicine for improving the clinical efficacy of chemotherapy.

DMPPQA, a novel angiogenesis inhibitor, induces apoptosis in human colon cancer HCT-116 cells and HUVECs

Cytotoxic activity of 5,7-dimethoxy-2-phenyl-N-propylquinolin-4-amine (DMPPQA) was investigated in human colon cancer cells HCT-116 and umbilical vein endothelial cell line HUVEC. The IC(50) of DMPPQA on HCT-116 and HUVEC cells were respectively 1.26 and 7.43 µM after 72 h treatment. DMPPQA inhibited the growth of HCT-116 and HUVEC cells in concentration- and time-dependent manners. Typical morphological changes of apoptotic body formation were seen after DMPPQA with Hoechst 33258 staining. FCM analysis showed that DMPPQA induced apoptosis, mitochondrial membrane potential loss (ΔΨm) and increase in the production of intracellular reactive oxygen species (ROS) of HCT-116 cells. After treating with DMPPQA, apoptosis-related protein expression of Bax, cytochrome c, caspase-9, caspase-3, PARP-1 and P53 increased and Bcl-2 protein expression decreased. DMPPQA treatment of HUVECs reduced cell migration and microcapillary tube formation in a Matrigel matrix. It also decreased VEGF protein expression. Thus DMPPQA acts as an angiogenesis inhibitor and induces cell apoptosis by a caspase-dependent mitochondrial pathway.

Lycopene modulates growth and survival associated genes in prostate cancer

Lycopene is a fat soluble red-orange carotenoid pigment present in tomato that reduces the risk for prostate cancer, a common malignancy among men. However, the mechanism by which lycopene attenuates prostate cancer is not fully defined. In this study we examined the effect of lycopene on proliferation, survival, and biomarker gene expression in prostate cancer (PC-3) cells in culture. WST-1 assay showed that lycopene induces a biphasic effect on PC-3 cells with a modest increase in proliferation at 1-5 μM, no change at 10-25 μM and a decrease at 50-100 μM doses in culture. Interestingly, combination treatment with lycopene induced anti-proliferative effect of Temozolomide on PC-3 cells. Lycopene also augmented the anti-proliferative effect of peroxisome proliferator-activated receptor gamma (PPARγ) agonists, but not Doxorubicin or Taxol, in prostate cancer. Flow cytometry analyses showed that lycopene, in combination with chemotherapeutic agents and PPARγ agonists, induced modest cell cycle arrest with significant increase in cell death by apoptosis and necrosis on prostate cancer. Gene array and quantitative reverse transcription polymerase chain reaction analyses showed that lycopene alters the expression of growth and apoptosis associated biomarkers in PC-3 cells. These findings highlight that lycopene attenuates prostate cancer by modulating the expression of growth and survival associated genes.

Overcoming multidrug resistance using liposomal epirubicin and antisense oligonucleotides targeting pump and nonpump resistances in vitro and in vivo

Multidrug resistance (MDR) is a serious obstacle in cancer treatment. In this study, epirubicin (Epi), an anthracycline antineoplastic agent, and/or antisense oligonucleotides (ASOs) targeting MDR1, MDR-associated protein (MRP)1, MRP2, and BCL-2/BCL-xL were incorporated into polyethylene glycol-coated (PEGylated) liposomes to develop a suitable anticancer drug delivery system. We evaluated in vitro cytotoxicity, intracellular accumulation and cell cycle analysis of these formulations. We also assessed in vivo pharmacokinetics and antitumor efficacy of these formulations in Sprague-Dawley (SD) rats and mouse colon adenocarcinoma CT26-bearing Balb/c mice. ASOs in PEGylated liposomes significantly enhanced the cytotoxicity and the intracellular accumulation of Epi in CT26 cells. This combination also intensified Epi-induced apoptosis in CT26 cells. An in vivo pharmacokinetic study using SD rats showed that after intravenous administration of PEGylated liposomal Epi and ASOs, Epi had greater area under the curve and longer half-life than in an Epi solution. The treatment of PEGylated liposomal Epi and ASOs also demonstrated significant improvements in tumor growth inhibition and survival percentage in CT26-bearing Balb/c mice in vivo. The PEGylated liposomal formulation of Epi and ASOs against MDR1, MRP1, MRP2, and BCL-2/BCL-xL exhibited the most pronounced effect among all the formulations used in this study. This study pioneered in demonstrating that PEGylated liposomal ASOs targeting both pump and nonpump resistances increase antitumor efficacy in vivo through the simultaneous inhibition of MDR transporters and apoptosis induction. This approach provides a potential strategy to overcome MDR in cancer chemotherapy.

Clusterin inhibition using OGX-011 synergistically enhances antitumour activity of sorafenib in a human renal cell carcinoma model

BACKGROUND

The objective of this study was to investigate whether the therapeutic activity of sorafenib could be enhanced by combining with OGX-011, an antisense oligodeoxynucleotide (ODN) targeting clusterin, in renal cell carcinoma (RCC).

METHODS

We investigated the effects of combined treatment with OGX-011 and sorafenib on a human RCC ACHN model both in vitro and in vivo.

RESULTS

Although clusterin expression was increased by sorafenib, additional treatment of ACHN with OGX-011 significantly blocked the upregulation of clusterin induced by sorafenib. Despite the lack of a significant effect on the growth of ACHN, OGX-011 synergistically enhanced the sensitivity to sorafenib, reducing the IC(50) by >50%. Apoptotic changes were intensively detected in ACHN after combined treatment with OGX-011 and a sublethal dose of sorafenib, but not either agent alone. Furthermore, this combined treatment resulted in the marked downregulation of phosphorylated Akt and p44/42 mitogen-activated protein kinase in ACHN compared with treatment with either agent alone. In vivo systemic administration of OGX-011 plus sorafenib significantly decreased the ACHN tumour volume compared with control ODN plus sorafenib.

CONCLUSION

Combined use with OGX-011 may be useful in enhancing the cytotoxic effect of sorafenib on RCC by inducing apoptosis and inactivating major signal transduction pathways.

Induction of DNA damage and caspase-independent programmed cell death by vitamin E

Vitamin E comprises 8 functionally unique isoforms and may be a suitable candidate for the adjuvant treatment of prostate cancer. In this study, we examined the ability of 2 vitamin E isoforms [α-tocotrienol (γ-TT) and δ-tocotrienol (δ-TT)] and 4 synthetic derivatives [γ- and δ-tocotrienol succinate (γ-TS, δ-TS), α-tocopheryl polyethylene glycol succinate (TPGS), and α-tocopheryl polyethylene glycol ether (TPGS-e)] of vitamin E to induce cell death in AR- (DU145 and PC-3) and AR+ (LNCaP) prostate cancer cell lines. Our results show that δ-TT and TPGS-e are the most effective isoform and synthetic derivative, respectively, of all compounds examined. Overall, the results of our study suggest that isoforms and synthetic derivatives of vitamin E have the potency to trigger both caspase-dependent and -independent DNA damage and dominant caspase-independent programmed cell death. The capacity of vitamin E to trigger caspase-independent programmed cell death suggests that it may be useful in the chemotherapy of prostate cancer since it may prevent the tumor resistance commonly associated with the use of classical chemotherapeutic agents that trigger caspase-dependent programmed cell death.

Pathways of chemotherapy resistance in castration-resistant prostate cancer

Chemotherapy remains the major treatment option for castration-resistant prostate cancer (CRPC) and limited cytotoxic options are available. Inherent chemotherapy resistance occurs in half of all patients and inevitably develops even in those who initially respond. Docetaxel has been the mainstay of therapy for 6 years, providing a small survival benefit at the cost of significant toxicity. Cabazitaxel is a promising second-line agent; however, it is no less toxic, whereas mitoxantrone provides only symptomatic benefit. Multiple cellular pathways involving apoptosis, inflammation, angiogenesis, signalling intermediaries, drug efflux pumps and tubulin are implicated in the development of chemoresistance. A thorough understanding of these pathways is needed to identify biomarkers that predict chemotherapy resistance with the aim to avoid unwarranted toxicities in patients who will not benefit from treatment. Until recently, the search for predictive biomarkers has been disappointing; however, the recent discovery of macrophage inhibitory cytokine 1 as a marker of chemoresistance may herald a new era of biomarker discovery in CRPC. Understanding the interface between this complex array of chemoresistance pathways rather than their study in isolation will be required to effectively predict response and target the late stages of advanced disease. The pre-clinical evidence for these resistance pathways and their progress through clinical trials as therapeutic targets is reviewed in this study.

Anticancer efficacy of deguelin in human prostate cancer cells targeting glycogen synthase kinase-3 β/β-catenin pathway

Activation of survival pathways has been associated with chemoresistance and progression of androgen independence which places a major obstacle to successful treatment of metastatic prostate cancer. Deguelin, a rotenoid isolated from Mundulea sericea, has an anticancer effect against several types of cancers; however, the mechanism of its antitumor effects on prostate cancer is not well understood. The aim of our study was to elucidate the effect of deguelin on the growth of prostate cancer cells and its putative mechanism of action. Deguelin decreased the viability of both androgen-dependent and -independent prostate cancer cells but not normal prostate epithelial cells. Downregulation of phosphorylated Akt and GSK-3β by deguelin promoted proteosomal degradation of β-catenin that resulted in decreased nuclear accumulation and inhibited transactivation of β-catenin-responsive genes. Deguelin-induced downregulation of proliferative (cyclin D1 and c-myc) and antiapoptotic proteins (Mcl-1, Bcl-xL and survivin) in prostate cancer cells culminated in the induction of apoptosis, inhibition of DNA synthesis and cell growth, altered membrane integrity, marked reduction of invasiveness, inhibition of anchorage-dependent and -independent colony formation. Our data demonstrated for the first time that deguelin inhibits the growth and survival of human androgen-independent prostate cancer cells, and its anticancer and antimetastatic activity occurs, at least in part through downregulating GSK-3β/β-catenin signaling pathway and antiapoptotic survival proteins. Taken together our study indicates that deguelin may have translational potential as therapeutic agent for advanced or metastatic prostate cancer.

Absence of p53 gene expression in selenium molecular prevention of chemically induced hepatocarcinogenesis in rats

BACKGROUND/AIM

p53 pathway is thought by many researchers to be critically involved in selenium's chemoprevention or in hepatocarcinogenesis. The aim of this study was to investigate the gene expression of p53, p21 and B-cell lymphoma-2 (bcl-2) using preventive and therapeutic approaches of selenium in chemically induced hepatocarcinogenesis in rats.

MATERIALS AND METHODS

Rats were divided randomly into six groups: Negative control, positive control (diethyl nitrosamine +2-acetylaminofluorene), preventive group, preventive control (respective control for preventive group), therapeutic group and therapeutic control (respective control for therapeutic group). p53, p21 and bcl-2 genes on liver tissues were measured using real-time polymerase chain reaction.

RESULTS

The expression of p53 was only significant in the therapeutic control. The expression of bcl-2 was insignificant in all the groups. p21 expression was significant in all the groups except the preventive group.

CONCLUSIONS

The selenium molecular mechanism for liver cancer prevention is not through the p53 pathway. Also, the absence of p53 is not necessary for chemically induced liver cancer in rats.

Inhibition of Bcl-2 and Bcl-X enhances chemotherapy sensitivity in hepatoblastoma cells

BACKGROUND

An increased expression of anti-apoptotic proteins is regularly found in malignant cells, contributing to their clonal expansion by conferring an improved survival ability. In Hepatoblastoma (HB) apoptosis regulation contributes to resistance and therapy failure, therefore we modulated apoptosis sensitivity of HB cells for an improved cytotoxic activity of commonly used drugs.

PROCEDURE

Apoptosis-related proteins were quantified in HB cells (HuH6 and HepT1) using protein assays. Interaction of ABT-737, a small-molecule inhibitor of Bcl-2, Bcl-xL, and Bcl-W with cytotoxic drugs was monitored in a proliferation assay. Apoptosis induction was measured by caspase-3 activity.

RESULTS

We found high levels of the anti-apoptotic protein Bcl-2 and Bcl-X as well as low levels of pro-apoptotic protein Bax and Bad in both HB cell lines. ABT-737 induced apoptosis in HuH6 and HepT1 cells at concentrations higher than 1 µM. ABT-737 also enhanced the cytotoxic effect of cisplatin (CDDP), doxorubicin (DOXO), etoposide and paclitaxel when used as combination therapy. HuH6 expressed slightly higher pro-apoptotic and lower anti-apoptotic protein levels than HepT1, which may explain the stronger enhancement of cytostatic drug effects in HuH6 cells when treated in combination with ABT-737.

CONCLUSION

The observed anti-apoptotic phenotype in HB cell lines may contribute to resistance to cytotoxic drugs used in the standard treatment protocol of HB. These pre-clinical results suggest that apoptosis sensitizers with BH-3 mimicry, such as ABT-737, should be further evaluated in preclinical models of HB.

Chemosensitization of prostate cancer by modulating Bcl-2 family proteins

A major challenge in oncology is the development of chemoresistance. This often occurs as cancer progresses and malignant cells acquire mechanisms to resist insults that would normally induce apoptosis. The onset of androgen independence in advanced prostate cancer is a prime example of this phenomenon. Overexpression of the pro-survival/anti-apoptotic proteins Bcl-2, Bcl-xL, and Mcl-1 are hallmarks of this transition. Here we outline the evolution of therapeutics designed to either limit the source or disrupt the interactions of these pro-survival proteins. By either lessening the stoichiometric abundance of Bcl-2/xL/Mcl-1 in reference to their pro-apoptotic foils or freeing these pro-apoptotic proteins from their grip, these treatments aim to sensitize cells to chemotherapy by priming cells for death. DNA anti-sense and RNA interference have been effectively employed to decrease Bcl-2 family mRNA and protein levels in cell culture models of advanced prostate cancer. However, clinical studies are lagging due to in vivo delivery challenges. The burgeoning field of nanoparticle delivery holds great promise in helping to overcome the challenge of administering highly labile nucleic acid based therapeutics. On another front, small molecule inhibitors that block the hetero-dimerization of pro-survival with pro-apoptotic proteins have significant clinical advantages and have advanced farther in clinical trials with promising early results. Most recently, a peptide has been discovered that can convert Bcl-2 from a pro-survival to a pro-apoptotic protein. The future may lie in targeting multiple steps of the apoptotic pathway, including Bcl-2/xL/Mcl-1, to debilitate the survival capacity of cancer cells and make chemotherapy induced death their only option.

Lysosomal destabilization and cathepsin B contributes for cytochrome c release and caspase activation in embelin-induced apoptosis

XIAP is an important antiapoptotic protein capable of conferring resistance to cancer cells. Embelin, the small molecular inhibitor of XIAP, possesses wide spectrum of biological activities with strong inhibition of nuclear factor kappa B and downstream antiapoptotic genes. However, the mechanism of its cell death induction is not known. Our studies using colon cancer cells lacking p53 and Bax suggest that both lysosomes and mitochondria are prominent targets of embelin-induced cell death. Embelin induced cell-cycle arrest in G(1) phase through p21, downstream of p53. In the absence of p21, the cells are sensitized to death in a Bax-dependent manner. The loss of mitochondrial membrane potential induced by embelin was independent of Bax and p53, but lysosomal integrity loss was strongly influenced by the presence of p53 but not by Bax. Lysosomal role was further substantiated by enhanced cathepsin B activity noticed in embelin-treated cells. p53-dependent lysosomal destabilization and cathepsin B activation contribute for increased sensitivity of p21-deficient cells to embelin with enhanced caspase 9 and caspase 3 activation. Cathepsin B inhibitor reduced cell death and cytochrome c release in embelin-treated cells indicating lysosomal pathway as the upstream of mitochondrial death signaling. Deficiency of cell-cycle arrest machinery renders cells more sensitive to embelin with enhanced lysosomal destabilization and caspase processing emphasizing its potential therapeutic importance to address clinical drug resistance.

Molecular targeted therapies for diffuse large B-cell lymphoma based on apoptosis profiles

Diffuse large B-cell lymphoma (DLBCL) is the most common type of adult non-Hodgkin lymphoma and is treated with chemotherapy in combination with rituximab. Despite this aggressive therapy, the disease is fatal in 30-40% of patients. Inhibition of the apoptosis signalling pathways is strongly related to response to chemotherapy and eventual clinical outcome. In order to survive, lymphoma cells depend on disruption of the apoptosis pathway by mutations in apoptosis inducing genes or by continuous expression of anti-apoptotic proteins. The development of molecules targeting these apoptosis inhibitors provides a very promising opportunity to specifically target tumour cells without toxicity to non-malignant cells in DLBCL patients. Sensitivity for most of these antagonists can be predicted based on biological markers, suggesting the possibility of pre-defining patients who will most likely benefit from these targeted therapies. Experimental therapies aimed at restoring the upstream apoptosis pathway or targeting apoptosis inhibitors are currently being tested in clinical trials and are expected to be effective particularly in chemotherapy-refractory DLBCL, providing hope for patients who are refractory to current therapies.

Novel targeted therapies for prostate cancer

This article reviews the concepts and rationale behind targeted agents that are currently in clinical testing for patients with castration resistant prostate cancer (CRPC). Advances in our understanding of the molecular mechanisms underlying prostate cancer progression has translated into a variety of treatment approaches. Agents targeting androgen receptor activation and local steroidogenesis, angiogenesis, apoptosis, chaperone proteins, the insulinlike growth factor pathway, RANK ligand, endothelin receptors, and Src family kinases are entering, or have recently completed, accrual to phase III trials for patients with CRPC. There has also been interest generated by data from early-phase studies evaluating multitargeted tyrosine kinase inhibitors, agents effecting signal transduction pathways, and novel cytotoxics.

YQ36: a novel bisindolylmaleimide analogue induces KB/VCR cell death

Overexpression of multidrug resistance proteins P-glycoprotein (P-gp, MDR1) causes resistance of the tumor cells against a variety of chemotherapeutic agents. 3-(1-methyl-1H-indol-3-yl)-1-phenyl-4-(1-(3-(piperidin-1-yl)propyl)-1H-pyrazolo[3,4-b]pyridine-3-yl)-1H-pyrrole-2,5-dione (YQ36) is a novel analogue of bisindolylmaleimide, which has been reported to overcome multidrug resistance. Here, we dedicated to investigate the anticancer activity of YQ36 on KB/VCR cells. The results revealed that YQ36 exhibited great antiproliferative activity on three parental cell lines and MDR1 overexpressed cell lines. Moreover, the hypersensitivity of YQ36 was confirmed on the base of great apoptosis induction and unaltered intracellular drug accumulation in KB/VCR cells. Further results suggested that YQ36 could not be considered as a substrate of P-gp, which contributed to its successfully escaping from the efflux mediated by P-gp. Interestingly, we observed that YQ36 could accumulate in nucleus and induce DNA damage. YQ36 could also induce the activation of caspase-3, imposing effects on the mitochondrial function. Collectively, our data demonstrated that YQ36 exhibited potent activities against MDR cells, inducing DNA damage and triggering subsequent apoptosis via mitochondrial pathway.

Efficient activation of p53 pathway in A549 cells exposed to L2, a novel compound targeting p53-MDM2 interaction

The tumor suppressor p53 plays a key role in the regulation of cell cycle, apoptosis, DNA repair, and senescence. It acts as a transcriptional factor, and is able to activate various genes to exert specific functions. MDM2, the main regulator of p53, inhibits the function of p53 through direct interaction. On the basis of this finding, inhibiting the MDM2-p53 interaction can be a potentially important target for cancer therapy. We showed here that L2, an analog of small-molecule MDM2 antagonist nutlins, stabilized p53 and selectively activated the p53 pathway in p53 wild-type A549 cells, resulting in a pronounced antiproliferation effect through inducing cell cycle arrest and apoptosis. Meanwhile, we confirmed by immunoprecipitation analysis that L2 could also inhibit MDM2-p53 interaction, similar to nutlin-1. Real-time PCR results revealed that L2 had no effect on the p53 gene transcriptional level, but it could induce the upregulation of p21 at the transcriptional level, which was the downstream of p53. Therefore, we concluded that the accumulation of p53 caused by L2 was mainly because of the decrease of the protein degradation rather than the elevation of p53 gene expression. Furthermore, no phosphor-p53 formed after L2 treatments, indicating that a genetoxic mechanism was unlikely to contribute to the activation of p53 by L2. In conclusion, the data acquired from A549 cells indicated that L2 exhibited high antiproliferation activity by disrupting MDM2-p53 interaction, and that the mechanism was derived from the activation of p53 and the p53 pathway. It was also surprising that L2 showed high antiproliferation effect against p53 null HL60 cells, which was quite different from nutlin-1. G2/M phase arrest might have contributed to the high antiproliferation activity of L2 on HL60 cells. The changes of p53 and MDM2 protein levels in L2-treated HL60 cells indicated that the mechanisms involved in the cell cycle arrest in A549 and HL60 cells were probably different, to which our future research would be devoted.

Systemic delivery of siRNA specific to tumor mediated by atelocollagen: combined therapy using siRNA targeting Bcl-xL and cisplatin against prostate cancer

The largest obstacle to the effective use of short interfering RNA (siRNA) in an animal body is the ability to deliver it to the target tissue. Here we showed a systemic delivery method of siRNA specific to pregrown solid tumors via atelocollagen. Atelocollagen facilitated the selective uptake of siRNA into the tumors when an siRNA/atelocollagen complex was administered intravenously to mice. We chose a Bcl-xL protein as a model target to prove the therapeutic efficacy of the atelocollagen-mediated method. Bcl-xL acts as an anti-apoptotic factor, which is overexpressed in many cancers, including prostate cancer. One of the four designed siRNAs to human Bcl-xL potently inhibited the expression of Bcl-xL by the PC-3 human prostate cancer cell line in vitro, leading to cell apoptosis. Intravenous injections for3 consecutive days (siRNA, 100 microg/injection per day as a complex with atelocollagen) effectively downregulated Bcl-xL expression in the PC-3 xenograft. We administered four series of 3 consecutive days of intravenous injections each, for a total of 12 injections, which significantly inhibited tumor growth when the treatment was combined with cisplatin (2 mg/kg). Local injection of Bcl-xL siRNA also potently inhibited tumor growth. All of the tumors treated with Bcl-xL siRNA/atelocollagen complex via both intravenous and intratumoral injection showed terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive apoptosis. There were no severe side effects such as interferon-alpha induction and liver or renal damage in mice. Our results indicate that systemic delivery of siRNA via atelocollagen, which specifically targets tumors, is safe and feasible for cancer therapy.

Growth factor receptors and apoptosis regulators: signaling pathways, prognosis, chemosensitivity and treatment outcomes of breast cancer

Biomarkers of breast cancer are necessary for prognosis and prediction to chemotherapy. Prognostic biomarkers provide information regarding outcome irrespective of therapy, while predictive biomarkers provide information regarding response to therapy. Candidate prognostic biomarkers for breast cancers are growth factor receptors, steroid receptors, Ki-67, cyclins, urokinase plasminogen activator, p53, p21, pro- and anti-apoptotic factors, BRCA1 and BRCA2. But currently, the predictive markers are Estrogen and Progesterone receptors responding to endocrine therapy, and HER-2 responding to herceptin. But there are numerous breast cancer cases, where tamoxifen is ineffective even after estrogen receptor positivity. This lead to search of new prognostic and predictive markers and the number of potential markers is constantly increasing due to proteomics and genomics studies. However, most biomarkers individually have poor sensitivity or specificity, or other clinical value. It can be resolved by studying various biomarkers simultaneously, which will help in better prognosis and increasing sensitivity for chemotherapeutic agents. This review is focusing on growth factor receptors, apoptosis markers, signaling cascades, and their correlation with other associated biomarkers in breast cancers. As our knowledge regarding molecular biomarkers for breast cancer increases, prognostic indices will be developed that combine the predictive power of individual molecular biomarkers with specific clinical and pathologic factors. Rigorous comparison of these existing as well as emerging markers with current treatment selection is likely to see an escalation in an era of personalized medicines to ensure the breast cancer patients receive optimal treatment. This will also solve the treatment modalities and complications related to chemotherapeutic regimens.

Depletion of intrinsic expression of Interleukin-8 in prostate cancer cells causes cell cycle arrest, spontaneous apoptosis and increases the efficacy of chemotherapeutic drugs

Background

The progression of all cancers is characterized by increased-cell proliferation and decreased-apoptosis. The androgen-independent prostate cancer (AIPC) is the terminal stage of the disease. Many chemokines and cytokines are suspects to cause this increased tumor cell survival that ultimately leads to resistance to therapy and demise of the host. The AIPC cells, but not androgen-responsive cells, constitutively express abundant amount of the pro-inflammatory chemokine, Interleukin-8 (IL-8). The mechanism of IL-8 mediated survival and therapeutic resistance in AIPC cells is unclear at present. The purpose of this report is to show the pervasive role of IL-8 in malignant progression of androgen-independent prostate cancer (AIPC) and to provide a potential new therapeutic avenue, using RNA interference.

Results

The functional consequence of IL-8 depletion in AIPC cells was investigated by RNA interference in two IL-8 secreting AIPC cell lines, PC-3 and DU145. The non-IL-8 secreting LNCaP and LAPC-4 cells served as controls. Cells were transfected with RISC-free siRNA (control) or validated-pool of IL-8 siRNA. Transfection with 50 nM IL-8 siRNA caused >95% depletion of IL-8 mRNA and >92% decrease in IL-8 protein. This reduction in IL-8 led to cell cycle arrest at G₁/S boundary and decreases in cell cycle-regulated proteins: Cyclin D1 and Cyclin B1 (both decreased >50%) and inhibition of ERK1/2 activity by >50%. Further, the spontaneous apoptosis was increased by >43% in IL-8 depleted cells, evidenced by increases in caspase-9 activation and cleaved-PARP. IL-8 depletion caused significant decreases in anti-apoptotic proteins, BCL-2, BCL-xL due to decrease in both mRNA and post-translational stability, and increased levels of pro-apoptotic BAX and BAD proteins. More significantly, depletion of intracellular IL-8 increased the cytotoxic activity of multiple chemotherapeutic drugs. Specifically, the cytotoxicity of Docetaxel, Staurosporine and Rapamycin increased significantly (>40% at IC₅₀ dose) in IL-8 depleted cells as compared to that in C-siRNA transfected cells.

Conclusion

These results show the pervasive role of IL-8 in promoting tumor cell survival, and resistance to cytotoxic drugs, regardless of the cytotoxic mechanism of antiproliferative drugs, and point to potential therapeutic significance of IL-8 depletion in men with AIPC.

Castration-resistant prostate cancer: from new pathophysiology to new treatment targets

CONTEXT

Castration-resistant prostate cancer (CRPC) refers to patients who no longer respond to surgical or medical castration. Standard treatment options are limited.

OBJECTIVE

To review the concepts and rationale behind targeted agents currently in late-stage clinical testing for patients with CRPC.

EVIDENCE ACQUISITION

Novel targeted therapies in clinical trials were identified from registries. The MEDLINE database was searched for all relevant reports published from 1996 to October 2009. Bibliographies of the retrieved articles and major international meeting abstracts were hand-searched to identify additional studies.

EVIDENCE SYNTHESIS

Advances in our understanding of the molecular mechanisms underlying prostate cancer (PCa) progression has translated into a variety of treatment approaches. Agents targeting androgen receptor (AR) activation and local steroidogenesis, angiogenesis, immunotherapy, apoptosis, chaperone proteins, the insulin-like growth factor (IGF) pathway, RANK-ligand, endothelin receptors, and the Src family kinases are entering or have recently completed accrual to phase 3 trials for patients with CRPC.

CONCLUSIONS

A number of new agents targeting mechanisms of PCa progression with early promising results are in clinical trials and have the potential to provide novel treatment options for CRPC in the near future.

ZD6474 inhibits Src kinase leading to apoptosis of imatinib-resistant K562 cells

ZD6474 is an orally available, small-molecule tyrosine kinase inhibitor. This study explores the effect of ZD6474 on imatinib-resistant K562 cell lines, which show markedly increased SRC family kinases (SFKs) activity. ZD6474 induces growth arrest and apoptosis of imatinib-resistant and parental K562 cells, as well as inhibition of Src activity and its downstream effectors, the anti-apoptotic Bcl-2 family. ZD6474 treatment also inhibits the activity of STAT3 and reactivation of its activity results in suppression of the anti-tumor effects of SFKs inhibitors. A single oral administration of ZD6474 produced dose-dependent inhibition of imatinib-resistant K562 cells xenograft tumors. These results suggest that clinical assessment of ZD6474 against imatinib-resistant CML is warranted.

Statistical interpretation of CA125 and Bcl-2 in serum of patients with late stage ovarian cancer

OBJECTIVES

The present study was conducted to investigate the sensitivity, specificity, predictive values and accuracy of serum CA125 and Bcl-2 levels and their combination in advanced epithelial ovarian cancer patients.

METHODS

Healthy controls (n = 117) with no gynecologic problems and patients with ovarian carcinoma (n = 117), pathologically verified, consecutively admitted to the Istanbul University, Oncology Institute during a one-year period were investigated. Serum Bcl-2 and CA125 were determined by using enzyme linked immunosorbent assay method.

RESULTS

The serum bcl-2 and CA125 levels were significantly higher in patients with ovarian cancer than in the control group (P < 0.001). The diagnostic sensitivity and specificity, predictive values and accuracies were calculated for each marker and their combination.

CONCLUSION

The best result was achieved with the combination of CA125-bcl-2. This combination fulfills the need of diagnosis of ovarian carcinoma for the best sensitivity and specificity.

Fish oil targets PTEN to regulate NFkappaB for downregulation of anti-apoptotic genes in breast tumor growth

The molecular mechanism for the beneficial effect of fish oil on breast tumor growth is largely undefined. Using the xenograft model in nude mice, we for the first time report that the fish oil diet significantly increased the level of PTEN protein in the breast tumors. In addition, the fish oil diet attenuated the PI 3 kinase and Akt kinase activity in the tumors leading to significant inhibition of NFkappaB activation. Fish oil diet also prevented the expression of anti-apoptotic proteins Bcl-2 and Bcl-XL in the breast tumors with concomitant increase in caspase 3 activity. To extend these findings we tested the functional effects of DHA and EPA, the two active omega-3 fatty acids of fish oil, on cultured MDA MB-231 cells. In agreement with our in vivo data, DHA and EPA treatment increased PTEN mRNA and protein expression and inhibited the phosphorylation of p65 subunit of NFkappaB in MDA MB-231 cells. Furthermore, DHA and EPA reduced expression of Bcl-2 and Bcl-XL. NFkappaB DNA binding activity and NFkappaB-dependent transcription of Bcl-2 and Bcl-XL genes were also prevented by DHA and EPA treatment. Finally, we showed that PTEN expression significantly inhibited NFkappaB-dependent transcription of Bcl-2 and Bcl-XL genes. Taken together, our data reveals a novel signaling pathway linking the fish oil diet to increased PTEN expression that attenuates the growth promoting signals and augments the apoptotic signals, resulting in breast tumor regression.

Chemosensitization of gemcitabine-resistant human bladder cancer cell line both in vitro and in vivo using antisense oligonucleotide targeting the anti-apoptotic gene, clusterin

OBJECTIVE

To characterize changes in clusterin (sCLU-2) expression in bladder cancer cells after continuous treatment with gemcitabine and to determine whether knockdown of sCLU-2 can re-introduce sensitivity of gemcitabine-resistant cells to treatment with gemcitabine.

MATERIALS AND METHODS

A human bladder cancer cell line, UM-UC-3, was continuously exposed to increasing doses of gemcitabine in vitro, and a gemcitabine-resistant cell line UM-UC-3R was developed. The role of sCLU-2 in chemoresistant phenotype acquired in both in vitro and in vivo was then analysed using antisense oligonucleotide targeting the sCLU-2 gene (OGX-011).

RESULTS

Treatment of parental UM-UC-3 cells (UM-UC-3P) with gemcitabine induced transient up-regulation of sCLU-2 protein. There was a sustained increase in sCLU-2 expression levels in UM-UC-3R compared with UM-UC-3P cells (6.4-fold). Treatment of UM-UC-3R cells with OGX-011 resulted in a dose-dependent and sequence- specific inhibition in sCLU-2 expression. Furthermore, OGX-011 chemo-sensitized UM-UC-3R cells to gemcitabine in vitro with a reduction in the concentration that reduces the effect by 50% (IC50) from 100 nm to 10 nm. Tumour volume and the incidence of metastasis in nude mice injected with UM-UC-3R cells was significantly greater than those of nude mice injected with UM-UC-3P cells; however, systemic administration of OGX-011 plus a low dose of gemcitabine significantly suppressed tumour volume and the incidence of metastasis in both groups.

CONCLUSION

These findings suggest that sCLU-2 plays a significant role in the acquisition of chemoresistant phenotype in bladder cancer cells and the knockdown of sCLU-2 using OGX-011 combined with a chemotherapeutic agent could be an attractive approach for advanced bladder cancer through the enhancement of chemosensitivity.

Adenovirus-mediated restoration of expression of the tumor suppressor gene DLC1 inhibits the proliferation and tumorigenicity of aggressive, androgen-independent human prostate cancer cell lines: prospects for gene therapy

Our recent study showing highly recurrent loss of function of DLC1 (deleted in liver cancer 1), a tumor suppressor gene in primary prostate carcinoma (PCA), implicates this gene in the pathogenesis of this disease. To evaluate the response of PCA to oncosuppressive activity of DLC1, we examined now the effects of adenoviral vector for human DLC1 transduction into the DLC1-deficient, androgen-independent (AI) and aggressive human PCA cell lines PC-3 and C4-2-B2. Adenovirus-mediated restoration of DLC1 expression inhibited the proliferation, invasiveness and anchorage-independent growth of PC-3 and C4-2-B2 cells in vitro as well as the tumorigenicity of PC-3 cells in nude mice. It also induced cell-cycle arrest, inhibited the activation of RhoA and the formation of actin stress fibers. DLC1 induced apoptosis in C4-2-B2 cells, whereas it did not elicit such an effect in PC-3 cells. The abundance of the antiapoptotic protein Bcl-2 was greater in PC-3 cells than in C4-2-B2 cells, and PC-3 cells were rendered sensitive to DLC1-induced apoptosis by treatment with the Bcl-2 inhibitor HA14-1. These results suggest that adenovirus-mediated DLC1 transfer, alone or together with other agents, such as inhibitors of Bcl-2 or histone deacetylase, might prove effective in the treatment of aggressive, AI-PCA.