Enhancement of Apo2L/TRAIL-mediated cytotoxicity in esophageal cancer cells by cisplatin

Non-coding RNA transcripts, incredible modulators of cisplatin chemo-resistance in bladder cancer through operating a broad spectrum of cellular processes and signaling mechanism

Bladder cancer (BC) is a highly frequent neoplasm in correlation with significant rate of morbidity, mortality, and cost. The onset of BC is predominantly triggered by environmental and/or occupational exposures to carcinogens, such as tobacco. There are two distinct pathways by which BC can be developed, including non-muscle-invasive papillary tumors (NMIBC) and non-papillary (or solid) muscle-invasive tumors (MIBC). The Cancer Genome Atlas project has further recognized key genetic drivers of MIBC along with its subtypes with particular properties and therapeutic responses; nonetheless, NMIBC is the predominant BC presentation among the suffering individuals. Radical cystoprostatectomy, radiotherapy, and chemotherapy have been verified to be the common therapeutic interventions in metastatic tumors, among which chemotherapeutics are more conventionally utilized. Although multiple chemo drugs have been broadly administered for BC treatment, cisplatin is reportedly the most effective chemo drug against the corresponding malignancy. Notwithstanding, tumor recurrence is usually occurred following the consumption of cisplatin regimens, particularly due to the progression of chemo-resistant trait. In this framework, non-coding RNAs (ncRNAs), as abundant RNA transcripts arise from the human genome, are introduced to serve as crucial contributors to tumor expansion and cisplatin chemo-resistance in bladder neoplasm. In the current review, we first investigated the best-known ncRNAs, i.e. microRNAs (miRNAs), long ncRNAs (lncRNAs), and circular RNAs (circRNAs), correlated with cisplatin chemo-resistance in BC cells and tissues. We noticed that these ncRNAs could mediate the BC-related cisplatin-resistant phenotype through diverse cellular processes and signaling mechanisms, reviewed here. Eventually, diagnostic and prognostic potential of ncRNAs, as well as their therapeutic capabilities were highlighted in regard to BC management.

The next generation therapy for lung cancer: taking medicine by inhalation

The inhalation administration method which has been applied to treat respiratory diseases has the characteristics of painlessness high efficiency and non-invasiveness, and the drug can also be targeted at the organ level first to reduce the loss of drug during circulation. Therefore, delivering medicine by inhalation administration has brought a new turnaround for lung cancer treatment. Herein from the perspective of combining traditional drug delivery design strategies with new drug delivery methods how to improve lung targeting efficiency and treatment efficacy is discussed. We also discuss the comparative advantages of inhaled drug delivery and traditional administration in the treatment of lung cancer such as intravenous injection. And the researches are divided into different forms of inhalation administration studied in the treatment of lung cancer in recent years, such as single-component loaded and multi-component loaded systems and their advantages. Finally, the obstacles of the application of carrier materials for inhalation administration and the prospects for improvement of lung cancer treatment methods are presented.

Epigenetic silencing of miR-200b is associated with cisplatin resistance in bladder cancer

In this study, we identified microRNAs (miRNAs) involved in cisplatin (CDDP) resistance in bladder cancer (BCa). After establishing CDDP-resistant BCa cell lines (T24RC and EJ138RC), TaqMan arrays revealed that members of the miR-200 family (miR-200b, miR-200a and miR-429) were downregulated in T24RC as compared to parental T24 cells. miR-200b was associated with CDDP sensitivity in BCa cells, and its downregulation was associated with CpG island hypermethylation. Pharmacological demethylation using 5-aza-2’-deoxycytidine restored miR-200b expression, and the combination of 5-aza-2’-deoxycytidine + CDDP strongly inhibited T24RC cell proliferation. Microarray analysis revealed that miR-200b + CDDP induced genes involved in CDDP sensitivity or cytotoxicity, including IGFBP3, ICAM1 and TNFSF10, in the resistant cells. Expression and DNA methylation of miR-200b were inversely associated in primary BCa, and low expression/high methylation was associated with poor overall survival. These results suggest downregulation of miR-200b is associated with CDDP resistance in BCa. Epigenetic silencing of miR-200b may be a marker of CDDP resistance and a useful therapeutic target for overcoming CDDP resistance in BCa.

Downregulation of SKP2 in Papillary Thyroid Cancer Acts Synergistically With TRAIL on Inducing Apoptosis via ROS

CONTEXT AND OBJECTIVE

S-phase kinase protein 2 (SKP2) is an F-box protein with proteasomal properties and has been found to be overexpressed in a variety of cancers. However, its role in papillary thyroid cancer (PTC) has not been fully elucidated.

EXPERIMENTAL DESIGN

SKP2 expression was assessed by immunohistochemistry in a tissue microarray format on a cohort of >1000 PTC samples. In vitro and in vivo studies were performed using proteasome inhibitor bortezomib and proapoptopic death ligand tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) either alone or in combination on PTC cell lines.

RESULTS

SKP2 was overexpressed in 45.5% of PTC cases and was significantly associated with extrathyroidal extension (P = 0.0451), distant metastasis (P = 0.0435), and tall cell variant (P = 0.0271). SKP2 overexpression was also directly associated with X-linked inhibitor of apoptosis protein overexpression (P < 0.0001) and Bcl-xL overexpression (P = 0.0005) and inversely associated with death receptor 5 (P < 0.0001). The cotreatment of bortezomib and TRAIL synergistically induced apoptosis via mitochondrial apoptotic pathway in PTC cell lines. Furthermore, bortezomib and TRAIL synergistically induced reactive oxygen species (ROS) generation and caused death receptor 5 upregulation through activation of the extracellular signal-regulated kinase-C/EBP homologous protein signaling cascade. Finally, bortezomib treatment augmented the TRAIL-mediated anticancer effect on PTC xenograft tumor growth in nude mice.

CONCLUSION

These data suggest that SKP2 is a potential therapeutic target in PTC and that a combination of bortezomib and TRAIL might be a viable therapeutic option for the treatment of patients with aggressive PTC.

Co-delivery of gambogic acid and TRAIL plasmid by hyaluronic acid grafted PEI-PLGA nanoparticles for the treatment of triple negative breast cancer

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-based combination therapy and gene therapy are new strategies to potentially overcome the limitations of TRAIL, however, the lack of efficient and low toxic vectors remains the major obstacle. In this study, we developed a hyaluronic acid (HA)-decorated polyethylenimine-poly(d,l-lactide-co-glycolide) (PEI-PLGA) nanoparticle (NP) system for targeted co-delivery of TRAIL plasmid (pTRAIL) and gambogic acid (GA) in triple-negative breast cancer (TNBC) therapy. GA was encapsulated into the core of the PEI-PLGA NPs while pTRAIL was adsorbed onto the positive NP surface via charge adsorption. The coating of HA on PEI-PLGA NPs functions as a targeting ligand by binding to CD44 receptor of TNBC cells and a shell to neutralize the excess positive charge of inner NPs. The resultant pTRAIL and GA co-loaded HA-coated PEI-PLGA NPs exhibited spherical shape (121.5 nm) and could promote the internalization of loaded cargoes into TNBC cells through the CD44-dependent endocytic pathway. The dual drug-loaded NPs significantly augmented apoptotic cell death in vitro and inhibited TNBC tumor growth in vivo. This multifunctional NP system efficiently co-delivered GA and pTRAIL, thus representing a promising strategy to treat TNBC and bringing forth a platform strategy for co-delivery of therapeutic DNA and chemotherapeutic agents in combinatorial TNBC therapy.

Cisplatin or LA-12 enhance killing effects of TRAIL in prostate cancer cells through Bid-dependent stimulation of mitochondrial apoptotic pathway but not caspase-10

Searching for new strategies for effective elimination of human prostate cancer cells, we investigated the cooperative cytotoxic action of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and two platinum-based complexes, cisplatin or LA-12, and related molecular mechanisms. We demonstrated a notable ability of cisplatin or LA-12 to enhance the sensitivity of several human prostate cancer cell lines to TRAIL-induced cell death via an engagement of mitochondrial apoptotic pathway. This was accompanied by augmented Bid cleavage, Bak activation, loss of mitochondrial membrane potential, activation of caspase-8, -10, -9, and -3, and XIAP cleavage. RNAi-mediated silencing of Bid or Bak in Bax-deficient DU 145 cells suppressed the drug combination-induced cytotoxicity, further underscoring the involvement of mitochondrial signaling. The caspase-10 was dispensable for enhancement of cisplatin/LA-12 and TRAIL combination-induced cell death and stimulation of Bid cleavage. Importantly, we newly demonstrated LA-12-mediated enhancement of TRAIL-induced cell death in cancer cells derived from human patient prostate tumor specimens. Our results provide convincing evidence that employing TRAIL combined with cisplatin/LA-12 could contribute to more effective killing of prostate cancer cells compared to the individual action of the drugs, and offer new mechanistic insights into their cooperative anticancer action.

Combinatorial treatment with anacardic acid followed by TRAIL augments induction of apoptosis in TRAIL resistant cancer cells by the regulation of p53, MAPK and NFκβ pathways

TRAIL, an apoptosis inducing cytokine currently in phase II clinical trial, was investigated for its capability to induce apoptosis in six different human tumor cell lines out of which three cell lines showed resistance to TRAIL induced apoptosis. To investigate whether Anacardic acid (A1) an active component of Anacardium occidentale can sensitize the resistant cell lines to TRAIL induced apoptosis, we treated the resistant cells with suboptimal concentration of A1 and showed that it is a potent enhancer of TRAIL induced apoptosis which up-regulates the expression of both DR4 and DR5 receptors, which has been observed in the cellular, protein and mRNA levels. The death receptors upregulation consequent to A1 treatment was corroborated by the activation of p53 as well as phosphorylation of p38 and JNK MAP kinases and concomitant inactivation of NFκβ and ERK signaling cascades. Also, A1 modulated the expression of key apoptotic players like Bax, Bcl-2 and CAD along with the abatement of tumor angiogenesis in vivo in EAT mouse model. Thus, post A1 treatment the TRAIL resistant cells turned into TRAIL sensitive cells. Hence our results demonstrate that A1 can synergize TRAIL induced apoptosis through the upregulation of death receptors and downregulation of anti-apoptotic proteins in cancer context.

Thapsigargin sensitizes human esophageal cancer to TRAIL-induced apoptosis via AMPK activation

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising anticancer agent for esophageal squamous cell carcinoma (ESCC). Forced expression of CHOP, one of the key downstream transcription factors during endoplasmic reticulum (ER) stress, upregulates the death receptor 5 (DR5) levels and promotes oxidative stress and cell death. In this study, we show that ER stress mediated by thapsigargin promoted CHOP and DR5 synthesis thus sensitizing TRAIL treatment, which induced ESCC cells apoptosis. These effects were reversed by DR5 siRNA in vitro and CHOP siRNA both in vitro and in vivo. Besides, chemically inhibition of AMPK by Compound C and AMPK siRNA weakened the anti-cancer effect of thapsigargin and TRAIL co-treatment. Therefore, our findings suggest ER stress effectively sensitizes human ESCC to TRAIL-mediated apoptosis via the TRAIL-DR5-AMPK signaling pathway, and that activation of ER stress may be beneficial for improving the efficacy of TRAIL-based anti-cancer therapy.

Macrophage Apoptosis Triggered by IpaD from Shigella flexneri

Shigellosis, a potentially severe bacillary dysentery, is an infectious gastrointestinal disease caused by Shigella spp. Shigella invades the human colonic epithelium and avoids clearance by promoting apoptosis of resident immune cells in the gut. This process is dependent on the Shigella type III secretion system (T3SS), which injects effector proteins into target cells to alter their normal cellular functions. Invasion plasmid antigen D (IpaD) is a structural component that forms a complex at the tip of the T3SS apparatus needle. Recently, IpaD has also been shown to indirectly induce apoptosis in B lymphocytes. In this study, we explored the cytotoxicity profile during macrophage infection by Shigella and discovered that the pathogen induces macrophage cell death independent of caspase-1. Our results demonstrate that IpaD triggers apoptosis in macrophages through activation of host caspases accompanied by mitochondrial disruption. Additionally, we found that the IpaD N-terminal domain is necessary for macrophage killing and SipD, a structural homologue from Salmonella, was found to promote similar cytotoxicity. Together, these findings indicate that IpaD is a contributing factor to macrophage cell death during Shigella infection.

Exploiting the potential of autophagy in cisplatin therapy: A new strategy to overcome resistance

Resistance to cisplatin is a major challenge in the current cancer therapy. In order to explore new therapeutic strategies to cisplatin resistance, we evaluated, in a model of lung cancer (H1299 and H460 cell lines), the nature of the pathways leading to cell death. We observed that H1299 displayed a natural resistance to cisplatin due to an inability to trigger an apoptotic response that correlates with the induction of autophagy. However, pharmacological and genetic approaches showed how autophagy was a mechanism associated to cell death rather than to resistance. Indeed, pro-autophagic stimuli such as mTOR or Akt inhibition mediate cell death in both cell lines to a similar extent. We next evaluated the response to a novel platinum compound, monoplatin, able to promote cell death in an exclusive autophagy-dependent manner. In this case, no differences were observed between both cell lines. Furthermore, in response to monoplatin, two molecular hallmarks of cisplatin response (p53 and MAPKs) were not implicated, indicating the ability of this pro-autophagic compound to overcome cisplatin resistance. In summary, our data highlight how induction of autophagy could be used in cisplatin resistant tumours and an alternative treatment for p53 mutated patient in a synthetic lethally approach.

Synergistic induction of apoptosis by mapatumumab and anthracyclines in human bladder cancer cells

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) triggers apoptosis in a variety of tumor cells by engaging the death receptors 4 (DR4) and 5 (DR5). We investigated the effect of chemotherapeutic drugs on DR4-mediated apoptosis in human bladder cancer cells, using a human monoclonal agonistic antibody specific for DR4, mapatumumab. Cytotoxicity was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Synergy was assessed by isobolographic analysis. Treatment of human bladder cancer T24 cells with mapatumumab in combination with mitomycin C, vinblastine or gemcitabine did not overcome resistance to these agents. However, treatment with mapatumumab in combination with epirubicin (EPI) had a synergistic cytotoxic effect. Synergy was also obtained in KU7 and RT112 human bladder cancer cells. A synergistic effect was also observed with mapatumumab in combination with pirarubicin. The synergy obtained in cytotoxicity with mapatumumab and EPI was also achieved in apoptosis. EPI markedly increased DR4 expression in the bladder cancer cells at both the mRNA and protein levels. Furthermore, the combination-induced cytotoxicity was significantly suppressed by the DR4:Fc chimeric protein. The combination of EPI and mapatumumab significantly activated the caspase cascade, including caspase-8, -9 and -3, which are the downstream molecules of death receptors. These findings indicate that EPI sensitizes bladder cancer cells to DR4-mediated apoptosis through induction of DR4 and activation of caspases, suggesting that the combination therapy of EPI and mapatumumab may be effective for bladder cancer therapy.

Ethanolic Neem (Azadirachta indica) Leaf Extract Prevents Growth of MCF-7 and HeLa Cells and Potentiates the Therapeutic Index of Cisplatin

The present study was designed to gain insight into the antiproliferative activity of ethanolic neem leaves extract (ENLE) alone or in combination with cisplatin by cell viability assay on human breast (MCF-7) and cervical (HeLa) cancer cells. Nuclear morphological examination and cell cycle analysis were performed to determine the mode of cell death. Further, to identify its molecular targets, the expression of genes involved in apoptosis, cell cycle progression, and drug metabolism was analyzed by RT-PCR. Treatment of MCF-7, HeLa, and normal cells with ENLE differentially suppressed the growth of cancer cells in a dose- and time-dependent manner through apoptosis. Additionally, lower dose combinations of ENLE with cisplatin resulted in synergistic growth inhibition of these cells compared to the individual drugs (combination index <1). ENLE significantly modulated the expression of bax, cyclin D1, and cytochrome P450 monooxygenases (CYP 1A1 and CYP 1A2) in a time-dependent manner in these cells. Conclusively, these results emphasize the chemopreventive ability of neem alone or in combination with chemotherapeutic treatment to reduce the cytotoxic effects on normal cells, while potentiating their efficacy at lower doses. Thus, neem may be a prospective therapeutic agent to combat gynecological cancers.

Doxorubicin-loaded porous PLGA microparticles with surface attached TRAIL for the inhalation treatment of metastatic lung cancer

Inhalable highly porous large PLGA microparticles with incorporated doxorubicin and surface-attached with TRAIL (TRAIL/Dox PLGA MP) were fabricated using a w/o/w double emulsification method using ammonium bicarbonate as a gas-foaming agent for the treatment of lung cancer. The TRAIL/Dox PLGA MP produced were highly porous and 11.5 ± 0.4 μm in diameter, and the loading efficiencies of Dox and TRAIL were 86.5 ± 6.5% and 91.8 ± 2.4%, respectively. TRAIL and doxorubicin were gradually released by TRAIL/Dox PLGA over 7 days, and pulmonary administration resulted in the deposition of TRAIL/Dox PLGA MP in mouse lungs, and they remained in situ for up to a week. The anti-tumor efficacy of pulmonary administered TRAIL/Dox PLGA MP was evaluated in a BALB/c nu/nu mice mouse model of H226 cell metastasis. Tumors in H226-implanted mice treated with TRAIL/Dox PLGA MP were markedly smaller and fewer in number than mice treated with TRAIL or Dox PLGA MP alone. Furthermore, this improved performance was found to be due to the synergistic apoptotic effects of the two drugs. We believe that TRAIL/Dox PLGA MP offer a promise of a sustained-release, long-acting, inhalable anti-lung cancer agent. Furthermore, the synergism observed between TRAIL and doxorubicin suggests that the doxorubicin dosage could be substantially reduced and its side effects minimized.

PMN and anti-tumor immunity--the case of bladder cancer immunotherapy

Urothelial carcinoma of the bladder accounts for ∼5% of all cancer deaths in humans. The majority of bladder tumors are non-muscle invasive at diagnosis, and there is a high rate of tumor recurrence and progression even after local surgical therapy. Thus, many patients require lifelong follow-up examinations that include additional prophylactic treatments in the event of recurrence. Since its first use in 1976, Mycobacterium bovis bacillus Calmette-Guerin (BCG) has been the treatment of choice for non-muscle invasive bladder cancer. Despite nearly 40 years of clinical use, the mechanism(s) by which intravesical administration of BCG results in elimination of bladder tumors remains undefined. Granulocytes (polymorphonuclear neutrophils (PMN)) are the predominant immune cell (in number) that enters the bladder after BCG installation, and a number of studies have highlighted the importance of PMN in the antitumor activity of BCG. Studies from our laboratory demonstrated presence of intracellular stores of the apoptosis-inducing protein TNF-related apoptosis-inducing ligand (TRAIL) in PMN that are rapidly released after interaction with BCG cell wall components, along with a correlation between increased urinary levels of TRAIL and BCG responsiveness. Mature PMN in circulation are terminally differentiated cells with limited biosynthetic capacity, so the proteins located in the distinct PMN granule populations are compartmentalized concomitant with their synthesis during myelopoiesis. Thus, understanding PMN production, localization, and release of TRAIL is important in the design of future BCG-based bladder tumor immunotherapy protocols.

Overexpression of cyclin B1 antagonizes chemotherapeutic-induced apoptosis through PTEN/Akt pathway in human esophageal squamous cell carcinoma cells

The role of cyclin B1 in the clinical therapeutic sensitivity of human esophageal squamous cell carcinoma (ESCC) remains to be defined. In this study, we found that elevated cyclin B1 expression attenuated the apoptosis induced by cisplatin or paclitaxel, while knockdown of cyclin B1 enhanced cisplatin or paclitaxel sensitivity in ESCC cells. Cyclin B1-mediated apoptosis may rely on the Bcl-2-dependent mitochondria-regulated intrinsic death pathway, and the antagonizing effect of cyclin B1 on chemotherapeutic agent-induced apoptosis was through PTEN/Akt pathway. Therefore, cyclin B1 might be a therapeutic target for the development of specific and efficient approaches in the treatment of ESCC.

Doxorubicin-loaded human serum albumin nanoparticles surface-modified with TNF-related apoptosis-inducing ligand and transferrin for targeting multiple tumor types

Human serum albumin (HSA) nanoparticles (NPs) surface modified with tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) and transferrin, and containing doxorubicin were designed and prepared. Surface amines of HSA were reversibly protected with dimethylmaleic anhydride (DMMA), and HSA-NPs were prepared using a desolvation technique. Furthermore, the surfaces of HSA-NPs were modified with thiolated TRAIL or transferrin using sulfosuccinimidyl-4-(N-maleimidomethyl)cyclohexane-1-carboxylate (Sulfo-SMCC). The prepared TRAIL/transferrin plus doxorubicin HSA-NPs were characterized by TEM, FE-SEM, and particle size analysis, and their cytotoxic and apoptotic activities were evaluated in several cancer cell lines, namely, HCT 116, doxorubicin-resistant MCF-7, and CAPAN-1. In addition, the tumor-targeting abilities of NPs were assessed using an infrared imaging system in HCT 116-xenografted nu/nu mice. Results showed that the TRAIL/transferrin/doxorubicin HSA-NPs had remarkable cytotoxic and apoptotic activities in all cancer cells examined with a general or a drug-resistant character, and that these NPs had obvious synergistic cytotoxic effects particularly on CAPAN-1 cells. Moreover, these HSA-NPs were effectively localized to tumors in a HCT 116-xenografted nu/nu mouse over 32 h. The findings of this study suggest that the described TRAIL/transferrin/doxorubicin HSA-NPs are a useful targeting agent capable of killing different types of tumor cells in various tissue organs.

Targeting p53 as a therapeutic strategy in sensitizing TRAIL-induced apoptosis in cancer cells

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) has been intensively studied as a cancer therapeutic agent due to its unique ability to induce apoptosis in malignant cells but not in normal cells. However, as more human cancer cells are reported to be resistant to TRAIL treatment, it is important to develop new therapeutic strategies to overcome this resistance. p53 is an important tumor suppressor that is widely involved in cellular responses to various stresses. In this mini-review, we aim to provide an overview of the intricate relationship between p53 and the TRAIL-mediated apoptosis pathway, and to summarize the current approaches of targeting p53 as a therapeutic strategy to sensitize TRAIL-induced apoptosis in human cancer cells. Although in some cases TRAIL kills cancer cells in a p53-independent manner, it is believed that in cancers with wild-type and functional p53, targeting p53 may be an important strategy for overcoming TRAIL-resistance in cancer therapy.

Phosphatidylinositol 3-Kinase-C2β Inhibits Cisplatin-Mediated Apoptosis via the Akt Pathway in Oesophageal Squamous Cell Carcinoma

A major problem in treating oesophageal squamous cell carcinoma (ESCC) with cisplatin is the development of drug resistance. In order to determine whether phosphatidylinositol 3-kinase (PI3K)-C2β (encoded by the PIK3C2B gene) reduced the sensitivity of ESCC to cisplatin, transfected Eca109 cells that overexpressed PIK3C2B were produced. Additionally, PI3K-C2β-siRNA was used to silence endogenous PI3K-C2β in EC9706 cisplatin-resistant cells. The relationship between PIK3C2B expression and clinicopathological characteristics was also investigated in samples from 61 patients. The overexpression of PIK3C2B in Eca109 cells significantly inhibited cisplatin-induced apoptosis and cleavage of caspase-3. Knockdown of PI3K-C2β enhanced cisplatin-induced apoptosis in EC9706 cells. PIK3C2B expression was associated with an increased level of phosphorylated Akt. Based on the tumour samples, expression of PIK3C2B was associated with tumour metastasis and in vitro assay suggested that it mediated cell migration. These results indicated that PI3K-C2β, via the Akt signalling pathway, might play a key role in cisplatin resistance and that targeting this pathway might be useful in treating cisplatin-resistant tumours.

Novel Anticancer Platinum(IV) Complexes with Adamantylamine: Their Efficiency and Innovative Chemotherapy Strategies Modifying Lipid Metabolism

The impressive impact of cisplatin on cancer on one side and severe side effects, as well as the development of drug resistance during treatment on the other side, were the factors motivating scientists to design and synthesize new more potent analogues lacking disadvantages of cisplatin. Platinum(IV) complexes represent one of the perspective groups of platinum-based drugs. In this review, we summarize recent findings on both in vitro and in vivo effects of platinum(IV) complexes with adamantylamine. Based on a literary overview of the mechanisms of activity of platinum-based cytostatics, we discuss opportunities for modulating the effects of novel platinum complexes through interactions with apoptotic signaling pathways and with cellular lipids, including modulations of the mitochondrial cell death pathway, oxidative stress, signaling of death ligands, lipid metabolism/signaling, or intercellular communication. These approaches might significantly enhance the efficacy of both novel and established platinum-based cytostatics.

Sensitization of human bladder tumor cells to TNF-related apoptosis-inducing ligand (TRAIL)-induced apoptosis with a small molecule IAP antagonist

Urothelial carcinoma of the bladder accounts for approximately 5% of all cancer deaths in humans. The large majority of bladder tumors are non-muscle invasive at diagnosis, but even after local surgical therapy there is a high rate of local tumor recurrence and progression. Current treatments extend time to recurrence but do not significantly alter disease survival. The objective of the present study was to investigate the tumoricidal potential of combining the apoptosis-inducing protein TNF-related apoptosis-inducing ligand (TRAIL) with a small molecule inhibitor of apoptosis proteins (IAP) antagonist to interfere with intracellular regulators of apoptosis in human bladder tumor cells. Our results demonstrate that the IAP antagonist Compound A exhibits high binding affinity to the XIAP BIR3 domain. When Compound A was used at nontoxic concentrations in combination with TRAIL, there was a significant increase in the sensitivity of TRAIL-sensitive and TRAIL-resistant bladder tumor lines to TRAIL-mediated apoptosis. In addition, modulation of TRAIL sensitivity in the TRAIL-resistant bladder tumor cell line T24 with Compound A was reciprocated by XIAP small interfering RNA-mediated suppression of XIAP expression, suggesting the importance of XIAP-mediated resistance to TRAIL in these cells. These results suggest the potential of combining Compound A with TRAIL as an alternative therapy for bladder cancer.

Oxaliplatin enhances TRAIL-induced apoptosis of gastric cancer BGC823 cells

AIM: To determine whether there is a synergistic effect between oxaliplatin and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in inducing the apoptosis of gastric cancer BGC823 cells.

METHODS: After BGC823 cells were cultured and treated with TRAIL and/or oxaliplatin, cell proliferation was measured using MTT assay; cell apoptosis was determined by flow cytometry after propidium iodide staining; and the distribution of lipid rafts and death receptors 4 (DR4) on cell membrane was analyzed by immunofluorescence staining with anti-cholera toxin B subunit, anti-DR4 antibody and rhodamine-conjugated fluorescent secondary antibody.

RESULTS: After BGC823 cells were treated with 1-1 000 µg/L TRAIL for 24 h, the reduced rates of cell proliferation did not exceed 20%. Treatment with 100 µg/L TRAIL for 24 h induced about 10% inhibition of cell proliferation and 4.12% ± 1.26% cell apoptosis. After BGC823 cells were treated with 1-50 mg/L oxaliplatin for 24 h, it was found that the half maximal inhibitory concentration (IC₅₀) was 37.36 mg/L ± 8.12 mg/L. Treatment with oxaliplatin (38 mg/L, IC₅₀ dose) plus TRAIL resulted in a dramatic increase in cell apoptosis when compared to treatment with TRAIL alone (19.83% ± 4.21% vs 40.42% ± 5.78%, P < 0.05). TRAIL at a concentration of 100 µg/L did not induce obvious lipid raft aggregation or DR4 clustering. Oxaliplatin (38 mg/L) significantly promoted lipid raft aggregation and DR4 clustering and induced the co-localization of DR4 and lipid rafts. Treatment with oxaliplatin and TRAIL for 24 h also induced DR4 clustering into aggregated lipid rafts.

CONCLUSION: Oxaliplatin enhances TRAIL-induced BGC823 cell apoptosis by clustering DR4 into lipid rafts.

Bortezomib sensitizes human esophageal squamous cell carcinoma cells to TRAIL-mediated apoptosis via activation of both extrinsic and intrinsic apoptosis pathways

Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive human cancers, and novel treatment modalities are required. We investigated the therapeutic potential of the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL/Apo2L) in combination with the proteasome inhibitor bortezomib (Velcade) on human ESCC cell lines. Bortezomib enhanced the susceptibility to TRAIL in 12 of the 15 ESCC cell lines tested, although most showed low sensitivity to TRAIL as a single agent. The enhancement of TRAIL-induced apoptosis by bortezomib was caspase dependent. Increased processing of caspase-8 often accompanied enhancement of TRAIL-induced apoptosis by bortezomib. However, the increased cell surface expression of death receptors observed on bortezomib treatment did not seem to be crucial for this effect. For some ESCC, bortezomib treatment resulted in a more efficient recruitment of caspase-8 and the Fas-associated death domain to the death-inducing signaling complex. Additional downregulation of the cellular FLICE-inhibitory protein long isoform [c-FLIP(L)] could cooperate in the activation of the extrinsic pathway in some cases. For other ESCC, the crucial effect of bortezomib treatment seemed to be increased signaling via the intrinsic apoptotic pathway on subsequent exposure to TRAIL. Thus, bortezomib could sensitize ESCC to TRAIL apoptosis by multiple molecular mechanisms of action. Therefore, the combination of bortezomib and TRAIL might be a novel therapeutic strategy for ESCC patients who fail to respond to standard chemoradiotherapy that predominantly targets the mitochondrial apoptotic pathway.

TRAIL and doxorubicin combination induces proapoptotic and antiangiogenic effects in soft tissue sarcoma in vivo

PURPOSE

Novel therapeutic approaches for complex karyotype soft tissue sarcoma (STS) are crucially needed. Consequently, we assessed the efficacy of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), in combination with chemotherapy, on local and metastatic growth of human STS xenografts in vivo.

EXPERIMENTAL DESIGN

TRAIL was evaluated alone and combined with low-dose doxorubicin in two human STS severe combined immunodeficient mouse xenograft models using fibrosarcoma (HT1080; wild-type p53) and leiomyosarcoma (SKLMS1; mutated p53), testing for effects on local growth, metastasis, and overall survival. Magnetic resonance imaging was used to evaluate local growth and bioluminescence was used to longitudinally assess lung metastases. Tissues were evaluated through immunohistocemistry and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining for treatment effects on tumor cell proliferation, apoptosis, angiogenesis, angiogenic factors, and TRAIL receptor expression. Quantitative real-time polymerase chain reaction (QRTPCR) angiogenesis array was used to assess therapy-induced gene expression changes.

RESULTS

TRAIL/doxorubicin combination induced marked STS local and metastatic growth inhibition in a p53-independent manner. Significantly increased (P < 0.001) host survival was also demonstrable. Combined therapy induced significant apoptosis, decreased tumor cell proliferation, and increased TRAIL receptor (DR4 and DR5) expression in all treated tumors. Moreover, decreased microvessel density was observed, possibly secondary to increased expression of the antiangiogenic factor CXCL10 and decreased proangiogenic interleukin-8 cytokine in response to TRAIL/doxorubicin combination, as was also observed in vitro.

CONCLUSIONS

Given the urgent need for better systemic approaches to STS, clinical trials evaluating TRAIL in combination with low-dose chemotherapy are potentially warranted.

Enhancement of lexatumumab-induced apoptosis in human solid cancer cells by Cisplatin in caspase-dependent manner

PURPOSE

This study was designed to evaluate the apoptotic effect of mapatumumab or lexatumumab, human agonistic antibodies that target the tumor necrosis factor-related apoptosis-inducing ligand receptor 1 (TRAIL-R1) and receptor 2 (TRAIL-R2), in combination with chemotherapeutic agents, against human solid cancer cells.

EXPERIMENTAL DESIGN

Cytotoxicity was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Synergy was assessed by isobolographic analysis.

RESULTS

Treatment of ACHN human renal cell carcinoma cells with cisplatin combined with mapatumumab did not overcome resistance to these agents. However, treatment with cisplatin in combination with lexatumumab had a synergistic cytotoxicity. Synergy was also achieved in six primary renal cell carcinoma cell cultures. Lexatumumab and cisplatin also synergistically enhanced apoptosis. Pretreatment with cisplatin followed by lexatumumab resulted in high cytotoxicity compared with the reverse sequence. Cisplatin significantly increased TRAIL-R2 expression at both the mRNA and the protein levels. Furthermore, the combination of lexatumumab and cisplatin significantly enhanced caspase-8 activity, Bid cleavage, up-regulation of Bax, cytochrome c release, and caspase-9, caspase-6, and caspase-3 activities. Importantly, the activation of caspase-8 was significantly abrogated by the specific inhibitors of caspase-9, caspase-6, and caspase-3. Furthermore, combination-induced cytotoxicity was significantly suppressed by the DR5:Fc chimeric protein and the specific inhibitors of caspase-8, caspase-9, caspase-6, and caspase-3. A similar effect was observed in prostate cancer, bladder cancer, lung cancer, and cervical cancer cells.

CONCLUSIONS

Cisplatin sensitizes solid cancer cells to lexatumumab-induced apoptosis by potentiation of the extrinsic and intrinsic apoptotic pathways that lead to amplification of caspase activation, particularly caspase-8, suggesting the combination treatment of solid cancers with cisplatin and lexatumumab might overcome their resistance.

TRAIL and Taurolidine induce apoptosis and decrease proliferation in human fibrosarcoma

BACKGROUND

Disseminated soft tissue sarcoma still represents a therapeutic dilemma because effective cytostatics are missing. Therefore we tested TRAIL and Tarolidine (TRD), two substances with apoptogenic properties on human fibrosarcoma (HT1080).

METHODS

Viability, apoptosis and necrosis were visualized by TUNEL-Assay and quantitated by FACS analysis (Propidiumiodide/AnnexinV staining). Gene expression was analysed by RNA-Microarray and the results validated for selected genes by rtPCR. Protein level changes were documented by Western Blot analysis. NFKB activity was analysed by ELISA and proliferation assays (BrdU) were performed.

RESULTS AND DISCUSSION

The single substances TRAIL and TRD induced apoptotic cell death and decreased proliferation in HT1080 cells significantly. Gene expression of several genes related to apoptotic pathways (TRAIL: ARHGDIA, NFKBIA, TNFAIP3; TRD: HSPA1A/B, NFKBIA, GADD45A, SGK, JUN, MAP3K14) was changed. The combination of TRD and TRAIL significantly increased apoptotic cell death compared to the single substances and lead to expression changes in a variety of genes (HSPA1A/B, NFKBIA, PPP1R15A, GADD45A, AXL, SGK, DUSP1, JUN, IRF1, MYC, BAG5, BIRC3). NFKB activity assay revealed an antipodal regulation of the several subunits of NFKB by TRD and TRD+TRAIL compared to TRAIL alone.

CONCLUSION

TRD and TRAIL are effective to induce apoptosis and decrease proliferation in human fibrosarcoma. A variety of genes seems to be involved, pointing to the NFKB pathway as key regulator in TRD/TRAIL-mediated apoptosis.

Cisplatin-mediated sensitivity to TRAIL-induced cell death in human granulosa tumor cells

OBJECTIVES

The goal of the present study was to determine the efficacy of combinatorial treatment using cisplatin and tumor necrosis factor-related apoptosis including ligand (TRAIL) to promote apoptosis in granulosa cell tumor (GCT) lines, in vitro.

METHODS

Two human GCT lines (COV434 and KGN) were treated with cisplatin or TRAIL, alone or in combination. The cytotoxic effects of each treatment were evaluated using a methyl tetrazolium salt (MTS) assay. Initiation of TRAIL-induced apoptosis was verified by PARP- and FLIP-cleavage. Overexpression and knockdown studies were conducted to evaluate the role of p53 in TRAIL-induced cell death. Real-time PCR was used for gene expression analysis of the TRAIL receptor dr5 and the pro-apoptotic bax following treatment with cisplatin.

RESULTS

Treatment with TRAIL (100-200 ng/ml) led to a slight, but significant, loss of cell viability following an 18-h culture. This effect was enhanced following pre-treatment with cisplatin (25 microM) for 2 or 18 h. Moreover, pre-treatment with cisplatin decreased the maximal effective dose of TRAIL from 100 ng/ml to as low as 3 ng/ml in both cell lines. GCT lines overexpressing or deficient in p53 were used to determine the requirement for p53 on TRAIL-induced apoptosis. While the level of p53 expression enhanced both the death-inducing and TRAIL-sensitizing effects of cisplatin, TRAIL-induced cell death was found to occur independent of p53.

CONCLUSIONS

These data suggest that the efficacy of cisplatin in GCT cells can be enhanced through combinatorial treatment with TRAIL. This result is due to both p53-dependent (cisplatin) and -independent (TRAIL) mechanisms. Combinatorial treatment of GCTs with cisplatin and TRAIL may provide an efficacious addition to cisplatin-based regimens.

The Essential Role of the Mitochondria and Reactive Oxygen Species in Cisplatin-Mediated Enhancement of Fas Ligand-Induced Apoptosis in Malignant Pleural Mesothelioma

Cytotoxic chemotherapeutic drugs such as cisplatin (CDDP) synergistically interact with soluble Fas ligand (sFasL) to mediate profound induction of apoptosis in cancer cells, particularly those refractory to this death-inducing ligand. The goal of this study was to evaluate the roles of the mitochondria-dependent apoptotic cascade and the CDDP-generated reactive oxygen species (ROS) in mediating the supra-additive enhancement of cytotoxicity and apoptosis in combination-treated malignant pleural mesothelioma (MPM) cells. MPM cells were treated with sequential CDDP/sFasL in vitro. Cell viability and apoptosis were determined by MTT and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assays. Stable transfectants expressing high levels of Bcl2 were created by retroviral gene transfer. Specific proteolytic activity of caspases 3, 8, and 9 were measured using fluorescent substrates. Pretreating MPM cells with CDDP increased their susceptibility to sFasL by 2- to more than 20-fold. Overexpression of either Bcl-2, the selective caspase 9 inhibitor z-LEHD-fmk, or the antioxidant N-acetylcysteine significantly abrogated combination-induced cytotoxicity and apoptosis. Moreover, the robust activation of caspase 8 in combination-treated cells was completely suppressed by Bcl-2 overexpression, thus implicating a mitochondria-mediated amplification feedback loop. As an in vivo correlate, sequential intraperitoneal administration of CDDP and sFasL significantly inhibited the growth of intraperitoneal MPM human xenografts in nude mice. Our data indicate that the mitochondria-dependent feedback loop of the caspase activation cascade and the generation of ROS are both essential in mediating profound cytotoxicity and apoptosis of MPM cells treated with CDDP and sFasL. This mechanistic study establishes a the translational framework for the clinical application of sequential CDDP/sFasL in the treatment of MPM.