Activation of Bak, Bax, and BH3-only proteins in the apoptotic response to doxorubicin

Doxorubicin and 4-nitrochalcone loaded in beeswax-based nanostructured lipid carriers: In vitro antitumoral screening and evaluation of synergistic effect on HepG-2 cells

Cancer is the second most deadly disease worldwide, and the most traditional approaches such as chemotherapy still face limitations associated to drug dosage and off-target side effects. To address these issues, we propose the simultaneous administration of 4-Nitrochalcone (4NC) and Doxorubicin (DOX) using beeswax based nanostructured lipid carriers (NLCs). The co-encapsulation of 4NC and DOX in the beeswax based NLCs was performed using the water/oil/water double emulsion technique in association with the melt dispersion approach. The system composed by semi-spherical NLCs with an average diameter around 200 nm and narrow size distribution, displayed colloidal stability before and after redispersion, keeping the zeta potential below -30 mV. The antitumor activity of the nanoparticles was screened on different tumor cell lines, and the induced cellular death and internal ROS levels were analyzed on hepatocarcinoma cells, which were found to be more affected by the combination of 4NC and DOX. The results indicated that 4NC + DOX-NCLs could promote cytotoxicity and oxidative damage-mediated apoptosis in a HepG-2 cell line.

Current trends in luminescence-based assessment of apoptosis

Apoptosis, the most extensively studied type of cell death, is known to play a crucial role in numerous processes such as elimination of unwanted cells or cellular debris, growth, control of the immune system, and prevention of malignancies. Defective regulation of apoptosis can trigger various diseases and disorders including cancer, neurological conditions, autoimmune diseases and developmental disorders. Knowing the nuances of the cell death type induced by a compound can help decipher which therapy is more effective for specific diseases. The detection of apoptotic cells using classic methods has brought significant contribution over the years, but innovative methods are quickly emerging and allow more in-depth understanding of the mechanisms, aside from a simple quantification. Due to increased sensitivity, time efficiency, pathway specificity and negligible cytotoxicity, these innovative approaches have great potential for both in vitro and in vivo studies. This review aims to shed light on the importance of developing and using novel nanoscale methods as an alternative to the classic apoptosis detection techniques.

p53 at the Crossroads between Doxorubicin-Induced Cardiotoxicity and Resistance: A Nutritional Balancing Act

Doxorubicin (DOX) is a highly effective chemotherapeutic drug, but its long-term use can cause cardiotoxicity and drug resistance. Accumulating evidence demonstrates that p53 is directly involved in DOX toxicity and resistance. One of the primary causes for DOX resistance is the mutation or inactivation of p53. Moreover, because the non-specific activation of p53 caused by DOX can kill non-cancerous cells, p53 is a popular target for reducing toxicity. However, the reduction in DOX-induced cardiotoxicity (DIC) via p53 suppression is often at odds with the antitumor advantages of p53 reactivation. Therefore, in order to increase the effectiveness of DOX, there is an urgent need to explore p53-targeted anticancer strategies owing to the complex regulatory network and polymorphisms of the p53 gene. In this review, we summarize the role and potential mechanisms of p53 in DIC and resistance. Furthermore, we focus on the advances and challenges in applying dietary nutrients, natural products, and other pharmacological strategies to overcome DOX-induced chemoresistance and cardiotoxicity. Lastly, we present potential therapeutic strategies to address key issues in order to provide new ideas for increasing the clinical use of DOX and improving its anticancer benefits.

Betulinic Acid-Doxorubicin-Drug Combination Induced Apoptotic Death via ROS Stimulation in a Relapsed AML MOLM-13 Cell Model

In this study, cell death regulation and induction in AML cell line from a relapsed MLL-rearranged cell model (MOLM-13) was investigated with doxorubin (Dox) and betulinic acid (BetA), singly and in combination. CyQUANT Direct^® and Annexin V/propidium iodide double staining were used to measure the cytotoxic and cell death induction effects of the compounds, respectively. Reactive oxygen species (ROS) generation was measured using 2′,7′-dichlorofluorescin diacetate staining. Expressions of proteins and genes were examined by Western blot and reverse transcription polymerase chain reaction analysis, respectively. BetA (20 μM) and Dox (1 μM) indicated a synergistic growth inhibitory effect on MOLM-13 cells. The combined drug caused more cells to reside in irreversible late apoptotic stage compared to the single treatments (p < 0.05). Elevation in ROS may be the synergistic mechanism involved in MOLM-13 cell death since ROS can directly disrupt mitochondrial activity. In contrast, in leukaemic U-937 cells, the combination treatments attenuated Dox-induced cell death. Dox and the drug combination selectively reduced (p < 0.05) a recently reported anti-apoptotic Bcl-2 protein isoform p15-20-Bcl-2 in MOLM-13 by our group, without affecting the usually reported p26-Bcl-2-α. Further studies using known inhibitors of apoptosis are required to confirm the potential of Dox-BetA combination to modulate these pathways.

Delivery of doxorubicin loaded P18 conjugated-poly(2-ethyl-oxazoline)-DOPE nanoliposomes for targeted therapy of breast cancer

Breast cancer, a heterogeneous disease, has the highest incidence rate and is a major cause of death in females worldwide. Drug delivery by using nanotechnology has shown great promise for improving cancer treatment. Nanoliposomes are known to have enhanced accumulation ability in tumors due to prolonged systemic circulation. Peptide 18 (P18), a tumor homing peptide targeting keratin-1 (KRT-1), was previously shown to have high binding affinity towards breast cancer cells. In this study, we investigate the ability of P18 conjugated PEtOx-DOPE nanoliposomes (P18-PEtOx-DOPE) for the targeted delivery of doxorubicin to AU565 breast cancer model. Toxicology studies of PEtOx-DOPE nanoliposomes performed on normal breast epithelial cells (MCF10A), showed minimal toxicity. Doxorubicin delivery by P18-PEtOx-DOPE to AU565 cells induces cytotoxicity in a dose and time dependent manner causing mitotic arrest in G2/M phase at 24 h. Anti-cancer activity of P18-PEtOx-DOPE-DOX nanoliposomes on AU565 cells was detected by Annexin V/PI apoptosis assay. In terms of in vivo antitumor efficacy, P18-PEtOx-DOPE-DOX nanoliposomes administration to AU565 CD-1 nu/nu mice model showed significant decrease in tumor volume suggesting that DOX delivered by these nanoliposomes elicited a strong antitumor response comparable to the free delivery of doxorubicin. Overall, our results offered preclinical proof for the use of P18-PEtOx-DOPE-DOX nanoliposomes in KRT-1⁺ breast cancer therapy.

BIK and GRP78 protein expression as possible markers of response to preoperative chemotherapy and survival in breast cancer

OBJECTIVE

BIK and GRP78 have shown differential expression profiles in breast cancer (BC) tissue, in addition to its important participation in the pathophysiology of cancer. The purpose of this study was to evaluate the association of BIK and GRP78 protein expression with clinical and pathologic response to preoperative chemotherapy, recurrence, disease-free survival (DFS) and overall survival (OS), in patients with BC.

MATERIAL AND METHODS

Fifty-three patients who received preoperative chemotherapy where included in an observational, analytical and retrospective study to assess the BIK and GRP78 protein expression by immunohistochemistry in microarrays of BC tissue obtained before treatment. Associations between BIK and GRP78 expression with clinicopathological characteristics, clinical and pathologic response to preoperative chemotherapy, and recurrence were analyzed using Chi-square or Fisher's exact test. OS and postoperative DFS were assessed at 5-year follow-up by Kaplan-Meir curves, and the difference according to BIK and GRP78 expression was evaluated using the log-rank test. Bivariate analysis was performed using Cox risk proportion model. A p value < 0.05 was considered to be statistically significant.

RESULTS

BIK and GRP78 staining revealed positive expression in 37 (71.2%) and 35 patients (72.9%) respectively. Association between pathological complete response (pCR) and positive expression of BIK (p = 0.046), as well as between clinical complete response (cCR) and negative expression of GRP78 was observed (p = 0.048). Patients with expression of GRP78 had lower DFS (HR = 3.46; 95% CI 1.01-11.80; p = 0.047) and shorter OS (HR = 3.49; 95% CI 1.04 a 11.72; p = 0.043).

CONCLUSION

When finding association of GRP78 and BIK protein expression with the response (clinical and pathologic respectively) to preoperative chemotherapy, and GRP78 with DFS and OS, in patients with BC, our results suggest a potential prognostic value of both proteins; however, a larger sample size is required to confirm this.

Novel pyrrolopyrimidine derivatives induce p53-independent apoptosis via the mitochondrial pathway in colon cancer cells

A series of novel pyrrolopyrimidine urea derivatives were synthesized and evaluated for their anticancer activity against colon cancer cell lines. Compounds showed the remarkable cytotoxic activity on HCT-116 wt cell line. The most potent compound 4c (IC₅₀ = 0.14 μM) induced apoptosis in HCT-116 wt and HCT-116 p53-/- cell lines. Otherwise, treatment of HCT-116 BAX-/-BAK-/- cells with compound 4c didn't lead to activation of apoptosis, suggesting that compound 4c induces apoptotic cell death by activating BAX/BAK-dependent pathway. Moreover, while the compound 4c increase the activation of caspase-3 and caspase-9 levels in HCT-116 wt and HCT-116 p53-/- cells, caspase-3 or caspase-9 activation was not observed in HCT-116 BAX-/-BAK-/- cells. In addition, compound 4c induced mitochondrial apoptosis in cells grown as oncospheroids, which better mimic the in vivo milieu of tumors. 4c treatment also activated JNK along with inhibition of prosurvival kinases such as Akt and ERK 1/2 in HCT-116 wt and HCT-116 p53 -/- cells as well as in HCT-116 BAX-/-BAK-/- cells. Notably, our results indicated that compound 4c induced mitochondrial apoptosis through activation p53-independent apoptotic signaling pathways.

Doxorubicin selectively induces apoptosis through the inhibition of a novel isoform of Bcl‑2 in acute myeloid leukaemia MOLM‑13 cells with reduced Beclin 1 expression

The overexpression of anti-apoptotic Bcl-2 in acute myeloid leukaemia (AML) may contribute to difficulties in eradicating these cells during chemotherapy. In the present study, doxorubicin (Dox) was evaluated for its potential to induce selective apoptotic cell death in AML MOLM-13 cells and to modulate autophagy through Bcl-2 and Beclin 1 protein expression. Annexin V/propidium iodide and 5(6)-carboxyfluorescein diacetate succinimidyl ester (CFSE) flow cytometric analyses were conducted to determine the effects of Dox on cell death and cell proliferation, respectively, following 48 h of co-incubation with AML MOLM-13 or U-937 monocytic cells. The protein expression levels of Bcl-2 and Beclin 1 in untreated and treated cells were quantified by western blot analysis. Dox reduced the viability of MOLM-13 cells partly by inhibiting cell division and inducing cell apoptosis. Dox demonstrated a level of selectivity in its cytotoxicity against MOLM-13 compared to U-937 cells (P<0.05). Dox induced a significant decrease in Beclin 1 protein levels in MOLM-13 cells without significantly affecting the protein levels in U-937 monocytes. A novel Bcl-2 15-20 kDa (p15-20-Bcl-2) isoform was found to be selectively expressed in AML MOLM-13 cells (but absent in the leukaemic cell lines tested, OCI-AML2, CML K562 and U-937). Dox induced a highly significant inhibition of p15-20-Bcl-2 at concentrations of 0.5, 0.75 and 1 µM (P<0.01). However, the usual 26 kDa Bcl-2 (p26-Bcl-2-α) isoform protein expression was not affected by the drug in either the MOLM-13 or U-937 cells. It was thus postulated that Dox exhibited some selectivity by targeting the p15-20-Bcl-2 isoform in MOLM-13 cells and activating Beclin 1 to induce cell death.

Activation of JNK signaling promotes all-trans-retinal-induced photoreceptor apoptosis in mice

Disrupted clearance of all-trans-retinal (atRAL), a component of the visual (retinoid) cycle in the retina, may cause photoreceptor atrophy in autosomal recessive Stargardt disease (STGD1) and dry age-related macular degeneration (AMD). However, the mechanisms underlying atRAL-induced photoreceptor loss remain elusive. Here, we report that atRAL activates c-Jun N-terminal kinase (JNK) signaling at least partially through reactive oxygen species production, which promoted mitochondria-mediated caspase- and DNA damage-dependent apoptosis in photoreceptor cells. Damage to mitochondria in atRAL-exposed photoreceptor cells resulted from JNK activation, leading to decreased expression of Bcl2 apoptosis regulator (Bcl2), increased Bcl2 antagonist/killer (Bak) levels, and cytochrome c (Cyt c) release into the cytosol. Cytosolic Cyt c specifically provoked caspase-9 and caspase-3 activation and thereby initiated apoptosis. Phosphorylation of JNK in atRAL-loaded photoreceptor cells induced the appearance of γH2AX, a sensitive marker for DNA damage, and was also associated with apoptosis onset. Suppression of JNK signaling protected photoreceptor cells against atRAL-induced apoptosis. Moreover, photoreceptor cells lacking Jnk1 and Jnk2 genes were more resistant to atRAL-associated cytotoxicity. The Abca4 ^-/- Rdh8 ^-/- mouse model displays defects in atRAL clearance that are characteristic of STGD1 and dry AMD. We found that JNK signaling was activated in the neural retina of light-exposed Abca4 ^-/- Rdh8 ^-/- mice. Of note, intraperitoneal administration of JNK-IN-8, which inhibits JNK signaling, effectively ameliorated photoreceptor degeneration and apoptosis in light-exposed Abca4 ^-/- Rdh8 ^-/- mice. We propose that pharmacological inhibition of JNK signaling may represent a therapeutic strategy for preventing photoreceptor loss in retinopathies arising from atRAL overload.

Gene Amplification-Driven Long Noncoding RNA SNHG17 Regulates Cell Proliferation and Migration in Human Non-Small-Cell Lung Cancer

Lung cancer is the most common cancer all around the world, with high morbidity and mortality. Long noncoding RNA (lncRNA) has been reported to have a critical role in non-small-cell lung cancer (NSCLC) proliferation and migration. In the present study, we analyzed The Cancer Genome Atlas (TCGA) data, and we found that lncRNA Small Nucleolar RNA Host Gene 17 (SNHG17) was upregulated in NSCLC driven by the amplification of copy number, indicating the special role of SNHG17 in NSCLC. The full exact length of SNHG17 was determined by rapid amplification of cDNA ends (RACE). We modulated SNHG17 expression by RNAi and a series of functional assays were performed. Flow cytometry was used to explore the involvement of SNHG17 in NSCLC cell apoptosis. Results showed that the knockdown of SNHG17 inhibited the proliferation and migration and promoted the apoptosis of NSCLC cells. We acquired the global gene expression profile regulated by SNHG17 in A549 through RNA sequencing (RNA-seq) assays. We found 637 genes were upregulated while 581 genes were downregulated. We selected three genes (FOXA1, XAF1, and BIK) that were closely related to proliferation and apoptosis, and we confirmed their altered expression in A549 and PC-9 cells treated with small interfering RNA si-SNHG17. Our findings indicated gene amplification-driven lncRNA SNHG17 promotes cell proliferation and migration in NSCLC, suggesting its potential value as a biomarker in NSCLC.

Hyperglycemia Promotes Chemoresistance Through the Reduction of the Mitochondrial DNA Damage, the Bax/Bcl-2 and Bax/Bcl-XL Ratio, and the Cells in Sub-G1 Phase Due to Antitumoral Drugs Induced-Cytotoxicity in Human Colon Adenocarcinoma Cells

Diabetes and cancer are common, chronic, and potentially fatal diseases that frequently co-exist. Observational studies clearly indicate that the risk of several types of cancer is increased in diabetic patients and a number of cancer types have shown a higher mortality rate in patients with hyperglycemic associated pathologies. This scenario could be due, at least in part, to a lower efficacy of the cancer treatments which needs to be better investigated. Here, we evaluated the effects of a prolonged exposure to high glucose (HG) to the response to chemotherapy on human colon adenocarcinoma HT29 and LOVO cell lines. We observed that hyperglycemia protected against the decreased cell viability and cytotoxicity and preserved from the mitochondrial DNA lesions induced by doxorubicin (DOX) and 5-fluorouracil (5-FU) treatments by lowering ROS production. In HT29 cells the amount of intracellular DOX and its nuclear localization were not modified by HG incubation in terms of Pgp, BCRP, MRP1, 5 and 8 activity and gene expression. On the contrary, in LOVO cells, the amount of intracellular DOX was significantly decreased after a bolus of DOX in HG condition and the expression and activity of MPR1 was increased, suggesting that HG promotes drug chemoresistance in both HT29 and LOVO cells, but in a different way. In both cell types, HG condition prevented the susceptibility to apoptosis by decreasing the ratio Bax/Bcl-2 and Bax/Bcl-XL and diminished the level of cytosolic cytochrome c and the cleavage of full length of PARP induced by DOX and 5-FU. Finally, hyperglycemia reduced cell death by decreasing the cell percentage in sub-G1 peak induced by DOX (via a cell cycle arrest in the G2/M phase) and 5-FU (via a cell cycle arrest in the S phase) in HT29 and LOVO cells. Taken together, our data showed that a prolonged exposure to HG protects human colon adenocarcinoma cells from the cytotoxic effects of two widely used chemotherapeutic drugs, impairing the effectiveness of the chemotherapy itself.

Distinct apoptotic blocks mediate resistance to panHER inhibitors in HER2+ breast cancer cells

Despite the development of novel targeted therapies, de novo or acquired chemoresistance remains a significant factor for treatment failure in breast cancer therapeutics. Neratinib and dacomitinib are irreversible panHER inhibitors, which block their autophosphorylation and downstream signaling. Moreover, neratinib and dacomitinib have been shown to activate cell death in HER2-overexpressing cell lines. Here we showed that increased MCL1 and decreased BIM and PUMA mediated resistance to neratinib in ZR-75-30 and SKBR3 cells while increased BCL-XL and BCL-2 and decreased BIM and PUMA promoted neratinib resistance in BT474 cells. Cells were also cross-resistant to dacomitinib. BH3 profiles of HER2+ breast cancer cells efficiently predicted antiapoptotic protein dependence and development of resistance to panHER inhibitors. Reactivation of ERK1/2 was primarily responsible for acquired resistance in SKBR3 and ZR-75-30 cells. Adding specific ERK1/2 inhibitor SCH772984 to neratinib or dacomitinib led to increased apoptotic response in neratinib-resistant SKBR3 and ZR-75-30 cells, but we did not detect a similar response in neratinib-resistant BT474 cells. Accordingly, suppression of BCL-2/BCL-XL by ABT-737 was required in addition to ERK1/2 inhibition for neratinib- or dacomitinib-induced apoptosis in neratinib-resistant BT474 cells. Our results showed that different mitochondrial apoptotic blocks mediated acquired panHER inhibitor resistance in HER2+ breast cancer cell lines as well as highlighted the potential of BH3 profiling assay in prediction of panHER inhibitor resistance in breast cancer cells.

Doxorubicin-induced loss of DNA topoisomerase II and DNMT1- dependent suppression of MiR-125b induces chemoresistance in ALK-positive cells

Systemic anaplastic large-cell lymphoma (ALCL) is a childhood T cell neoplasm defined by the presence or absence of translocations that lead to the ectopic expression of anaplastic lymphoma kinase (ALK), with nucleophosmin-ALK (NPM-ALK) fusions being the most common. Polychemotherapy involving doxorubicin is the standard first-line treatment but for the 25 to 35% of patients who relapse and develop resistance the prognosis remains poor. We studied the potential role of the microRNA miR-125b in the development of resistance to doxorubicin in NPM-ALK(+) ALCL. Our results show that miR-125b expression is repressed in NPM-ALK(+) cell lines and patient samples through hypermethylation of its promoter. NPM-ALK activity, in cooperation with DNA topoisomerase II (Topo II) and DNA methyltransferase 1 (DNMT1), is responsible for miR-125b repression through DNA hypermethylation. MiR-125b repression was reversed by the inhibition of DNMTs with decitabine or the inhibition of DNA topoisomerase II with either doxorubicin or etoposide. In NPM-ALK(+) cell lines, doxorubicin treatment led to an increase in miR-125b levels by inhibiting the binding of DNMT1 to the MIR125B1 promoter and downregulating the pro-apoptotic miR-125b target BAK1. Reversal of miR-125b silencing, increased miR-125b levels and reduced BAK1 expression also led to a lower efficacy of doxorubicin, suggestive of a pharmacoresistance mechanism. In line with this, miR-125b repression and increased BAK1 expression correlated with early relapse in human NPM-ALK(+) ALCL primary biopsies. Collectively our findings suggest that miR-125b could be used to predict therapeutic outcome in NPM-ALK(+) ALCL.

Downregulation of transcription factor GATA4 sensitizes human hepatoblastoma cells to doxorubicin-induced apoptosis

Hepatoblastoma, the most common type of pediatric liver cancer, is treated with a combination of surgery and chemotherapy. An essential drug in the treatment of hepatoblastoma is doxorubicin, which in high doses is cardiotoxic. This adverse effect is due to downregulation of cardiac expression of transcription factor GATA4, leading in turn to diminished levels of anti-apoptotic BCL2 (B-cell lymphoma 2) protein family members. GATA4 is also expressed in early fetal liver, but absent from normal postnatal hepatocytes. However, GATA4 is highly expressed in hepatoblastoma tissue. In this study, we assessed the role of GATA4 in doxorubicin-induced apoptosis of hepatoblastoma cells. Herein, we demonstrate that doxorubicin decreases GATA4 expression and alters the expression pattern of BCL2 family members, most profoundly that of BCL2 and BAK, in the HUH6 hepatoblastoma cell line. Silencing of GATA4 by siRNA prior to doxorubicin treatment sensitizes HUH6 cells to the apoptotic effect of this drug by further shifting the balance of BCL2 family members to the pro-apoptotic direction. Specifically, expression levels of anti-apoptotic BCL2 were decreased and pro-apoptotic BID were increased after GATA4 silencing. On the whole, our results indicate that since high endogenous levels of transcription factor GATA4 likely protect hepatoblastoma cells from doxorubicin-induced apoptosis, these cells can be rendered more sensitive to the drug by downregulation of GATA4.

Sorafenib-induced defective autophagy promotes cell death by necroptosis

Autophagy is one of the main cytoprotective mechanisms that cancer cells deploy to withstand the cytotoxic stress and survive the lethal damage induced by anti-cancer drugs. However, under specific conditions, autophagy may, directly or indirectly, induce cell death. In our study, treatment of the Atg5-deficient DU145 prostate cancer cells, with the multi-tyrosine kinase inhibitor, sorafenib, induces mitochondrial damage, autophagy and cell death. Molecular inhibition of autophagy by silencing ULK1 and Beclin1 rescues DU145 cells from cell death indicating that, in this setting, autophagy promotes cell death. Re-expression of Atg5 restores the lipidation of LC3 and rescues DU145 and MEF atg5−/− cells from sorafenib-induced cell death. Despite the lack of Atg5 expression and LC3 lipidation, DU145 cells form autophagosomes as demonstrated by transmission and immuno-electron microscopy, and the formation of LC3 positive foci. However, the lack of cellular content in the autophagosomes, the accumulation of long-lived proteins, the presence of GFP-RFP-LC3 positive foci and the accumulated p62 protein levels indicate that these autophagosomes may not be fully functional. DU145 cells treated with sorafenib undergo a caspase-independent cell death that is inhibited by the RIPK1 inhibitor, necrostatin-1. Furthermore, treatment with sorafenib induces the interaction of RIPK1 with p62, as demonstrated by immunoprecipitation and a proximity ligation assay. Silencing of p62 decreases the RIPK1 protein levels and renders necrostatin-1 ineffective in blocking sorafenib-induced cell death. In summary, the formation of Atg5-deficient autophagosomes in response to sorafenib promotes the interaction of p62 with RIPK leading to cell death by necroptosis.

Targeted expression of BikDD combined with metronomic doxorubicin induces synergistic antitumor effect through Bax activation in hepatocellular carcinoma

Conventional chemotherapy is commonly used to treat advanced non-resectable hepatocellular carcinoma (HCC) but this treatment modality has not demonstrated convincing survival benefit in HCC patients. Our previous studies indicated that targeted expression of therapeutic BikDD driven by a liver cancer-specific α-fetoprotein promoter/enhancer (eAFP) in the VISA backbone (eAFP-VISA-BikDD) significantly and specifically kills HCC cells in multiple orthotopic animal models. To enhance its therapeutic efficacy, we combined eAFP-VISA-BikDD with chemotherapeutic agents and found that eAFP-VISA-BikDD plus doxorubicin (Dox) or 5-fluorouracil (5-FU) demonstrated synergistic cytotoxicity in HCC cells. Specifically, the combination of eAFP-VISA-BikDD plus Dox markedly induced apoptosis via increased Bax mitochondrial translocation and cytoplasmic cytochrome c release. Compared with either agent alone, a low dose of Dox combined with eAFP-VISA-BikDD induced better antitumor effect and prolonged longer survival of mice in two orthotopic liver cancer xenograft models. Our findings provide strong preclinical support for evaluating the combined therapy of eAFP-VISA-BikDD and Dox in a clinical setting as a treatment option for HCC.

Apoptosis of human pancreatic carcinoma cell-1 cells induced by Yin Chen Hao Decoction

AIM

To evaluate human pancreatic carcinoma cell line (PANC-1) cells apoptosis and Bcl-2 and Bax expression induced by Yin Chen Hao Decoction (YCHD).

METHODS

The cell growth inhibitory rate was determined by MTT assay. Apoptosis of PANC-1 cells before and after treatment with YCHD was determined by TUNEL staining. Expression of the apoptosis-associated genes, Bcl-2 and Bax, was detected by immunohistochemical staining and reverse transcription -PCR.

RESULTS

YCHD inhibited the growth of PANC-1 cells. Following treatment with YCHD for 24-96 h, the apoptotic rate of PANC-1 cells increased with time. In addition, the positive rate of Bcl-2 protein expression decreased in a time-dependent manner, whereas the positive rate of Bax protein expression increased in a time-dependent manner. Following treatment of with YCHD for 24-96h, expression of BAX mRNA increased gradually and BCL-2 mRNA reduced gradually with time.

CONCLUSION

YCHD induces apoptosis of PANC-1 cells mediated in part via up-regulation of BAX and down-regulation of BCL-2.

The Tumor Suppressive Effects of HPP1 Are Mediated Through JAK-STAT-Interferon Signaling Pathways

HPP1, a novel tumor suppressive epidermal growth factor (EGF)-like ligand, mediates its effects through signal transducer and activators of transcription (STAT) activation. We previously demonstrated the importance of STAT1 activation for HPP1 function; however the contribution of STAT2 remains unclear. We sought to delineate the components of JAK-STAT-interferon (IFN) signaling specifically associated with HPP1s biological effects. Using stable HPP1-HCT116 transfectants, expression analyses were performed by polymerase chain reaction (PCR)/western blotting while expression knockdowns were achieved using siRNA. Growth parameters evaluated included proliferation, cell cycle distribution, and anchorage-independent growth. STAT dimerization, translocation, and DNA binding were examined by reporter assays, fluorescent microscopy, and chromatin immunoprecipitation (ChIP), respectively. Forced expression of HPP1 in colon cancer cell lines results in the upregulation of total and activated levels of STAT2. We have also determined that JAK1 and JAK2 are activated in response to HPP1 overexpression, and are necessary for subsequent STAT activation. Overexpression of HPP1 was associated with significant increases in STAT1:STAT1 (p=0.007) and STAT1:STAT2 (p=0.036) dimer formation, as well as subsequent nuclear translocation. By ChIP, binding of activated STAT1 and STAT2 to the interferon-signaling regulatory element promoter sites of the selected genes, protein kinase RNA-activated (PKR), IFI44, and OAS1 was demonstrated. STAT2 knockdown resulted in partial abrogation of HPP1s growth suppressive activity with increased proliferation (p<0.0001), reduced G1/G0 phase cell cycle fraction, and a restoration of growth potential in soft agar (p<0.01). Presumably as a consequence of upregulation of IFN signaling elements, HPP1 overexpression resulted in an acquisition of exogenous IFN sensitivity. Physiologic doses of IFN-α resulted in a significant reduction in proliferation (p<0.001) and increase in G1/G0 cell cycle arrest in HPP1 transfectants. STAT2 is necessary for HPP1-associated growth suppression, and mediates these effects through activation of IFN-α pathways. Given the interest in therapeutic targeting of oncogenic erbB proteins, further understanding of HPP1s role as a tumor suppressive EGF-like ligand is warranted.

ChBax/Bak as key regulators of the mitochondrial apoptotic pathway: cloned and characterized in Crassostrea hongkongensis

Apoptosis has been primarily investigated in mammals, and little is known about apoptosis in mollusks. The proteins Bax and Bak play critical roles in the mitochondrial apoptosis pathway and in determining cell fate. In this study, ChBax and ChBak, homologs of the well-known Bax and Bak proteins, were identified from the oyster Crassostrea hongkongensis. The ChBax/Bak proteins consist of 207/232 amino acids with the typical domains found in BCL-2 family members. ChBax and ChBak mRNA expression were detected in all 8 of the selected oyster tissues and at the different stages of development. Fluorescence microscopy revealed that the full-length proteins of ChBax/Bak were located in the cytoplasm and mitochondrial outer membrane, of HEK293T cells, respectively. Furthermore, both of the genes' expression levels were found to increase in the hemocytes of oysters challenged with pathogens. The over-expression of ChBax or ChBak activates the p53-Luc reporter gene in HEK293T cells in a dose-dependent manner. These results indicate that ChBax and ChBak may play important roles in the mitochondrial apoptotic pathway in oysters.

Small molecule inhibitor YM155-mediated activation of death receptor 5 is crucial for chemotherapy-induced apoptosis in pancreatic carcinoma

Despite much effort, pancreatic cancer survival rates are still dismally low. Novel therapeutics may hold the key to improving survival. YM155 is a small molecule inhibitor that has shown antitumor activity in a number of cancers by reducing the expression of survivin. The aim of our study is to understand the mechanisms by which YM155 functions in pancreatic cancer cells. We established the antitumor effect of YM155 with in vitro studies in cultured cells, and in vivo studies using a mouse xenograft model. Our data demonstrated that YM155 reduced the expression of survivin; however, downregulation of survivin itself is insufficient to induce apoptosis in pancreatic cancer cells. We showed for the first time that treatment with YM155 increased death receptor 5 (DR5) expression in pancreatic cancer cells. We found that YM155 induced apoptosis by broad-spectrum inhibition of IAP family member proteins (e.g., CIAP1/2 and FLIP) and induced proapoptotic Bak protein upregulation and activation; the antitumor effect of YM155 treatment with either the DR5 agonist lexatumumab or gemcitabine on pancreatic cancer cells was synergistic. Our data also revealed that YM155 inhibits tumor growth in vivo, without apparent toxicity to the noncancerous human pancreatic ductal epithelial cell line. Together, these findings suggest that YM155 could be a novel therapeutic agent for pancreatic cancer.

Small Molecule Inhibitor YM155-Mediated Activation of Death Receptor 5 Is Crucial for Chemotherapy-Induced Apoptosis in Pancreatic Carcinoma

Despite much effort, pancreatic cancer survival rates are still dismally low. Novel therapeutics may hold the key to improving survival. YM155 is a small molecule inhibitor that has shown antitumor activity in a number of cancers by reducing the expression of survivin. The aim of our study is to understand the mechanisms by which YM155 functions in pancreatic cancer cells. We established the antitumor effect of YM155 with in vitro studies in cultured cells, and in vivo studies using a mouse xenograft model. Our data demonstrated that YM155 reduced the expression of survivin; however, downregulation of survivin itself is insufficient to induce apoptosis in pancreatic cancer cells. We showed for the first time that treatment with YM155 increased death receptor 5 (DR5) expression in pancreatic cancer cells. We found that YM155 induced apoptosis by broad-spectrum inhibition of IAP family member proteins (e.g., CIAP1/2 and FLIP) and induced proapoptotic Bak protein upregulation and activation; the antitumor effect of YM155 treatment with either the DR5 agonist lexatumumab or gemcitabine on pancreatic cancer cells was synergistic. Our data also revealed that YM155 inhibits tumor growth in vivo, without apparent toxicity to the noncancerous human pancreatic ductal epithelial cell line. Together, these findings suggest that YM155 could be a novel therapeutic agent for pancreatic cancer. Mol Cancer Ther; 14(1); 80–89. ©2014 AACR.

Induction of apoptosis by doxorubicin-transferrin conjugate compared to free doxorubicin in the human leukemia cell lines

In our research we compared the effect of doxorubicin (DOX) and doxorubicin-transferrin (DOX-TRF) conjugate on the induction of programmed cell death. All experiments were carried out on human leukemia cells: CCRF-CEM, K562 sensitive and resistant to DOX, (K562/DOX), which are the molecular model for the chronic and acute form of hematological malignancies, respectively. At the same time, studies were also performed on normal, peripheral blood mononuclear cells (PBMCs). The first stages of apoptosis, connected with externalization of phosphatidylserine (PS), were evaluated after comparing the viability of tested cell lines treated with DOX-TRF conjugate or free DOX. Morphological changes of nuclei connected with apoptosis were analyzed by double staining Hoechst 33258/propidium iodide. Subsequently, we conducted a more accurate evaluation of DOX-TRF-trigged cell death by using DNA ladder assay, measuring the activation of caspase-3, -8 and -9 and changes in poly-ADP ribose polymerase (PARP) activity. The percentage of apoptotic cells reached its maximum at 24 and 48 h incubation. Prolonged treatment time with DOX-TRF conjugate progressively increased the level of necrotic cells. At 24-48 h time points, we observed a significant increase in the activity of apoptosis-characterized enzymes (caspases -8, -9, -3). This study provided the evidence that DOX-TRF conjugate triggers apoptotic pathway connected with DNA damage mediated by the activation of pro-caspases and PARP cleavage.

Doxorubicin induced apoptosis was potentiated by neferine in human lung adenocarcima, A549 cells

Doxorubicin (DOX) is the best anticancer agent that has ever been used, but acquired tumor resistance and dose limiting toxicity are major road blocks. Concomitant use of natural compounds is a promising strategy to overcome this problem. Neferine, a proven anticancer agent is found in green embryos of lotus seed. The study demonstrates that neferine acts as an effective enhancer of DOX-induced cell death in A549 cells through ROS mediated apoptosis with MAPK activation and inhibition of NF-κB nuclear translocation. Cotreatment of cells with neferine significantly enhanced intracellular DOX-accumulation. Neferine and DOX in combination also triggered oxidative stress through intracellular Ca(2+) accumulation and dissipation of mitochondrial membrane potential in addition to significant loss of cellular antioxidant pool. The MAPK inhibitor effectively decreased the cell-death induced by neferine and DOX. Pretreatment of cells with glutathione reversed the apoptosis induced by combined regimen and recovered the Bcl2/Bax ratio. Moreover, neferine treatment significantly increased the cell viability of DOX-treated cardiomyocytes indicating a possible protective role of neferine towards DOX-induced cardiotoxicity. Taken together, our results suggest that a strategy of using neferine and DOX in combination could be helpful to increase the efficacy of DOX and to achieve anticancer synergism by curbing the toxicity.

Argon gas: a potential neuroprotectant and promising medical therapy

Argon is a noble gas element that has demonstrated narcotic and protective abilities that may prove useful in the medical field. The earliest records of argon gas have exposed its ability to exhibit narcotic symptoms at hyperbaric pressures greater than 10 atmospheres with more recent evidence seeking to display argon as a potential neuroprotective agent. The high availability and low cost of argon provide a distinct advantage over using similarly acting treatments such as xenon gas. Argon gas treatments in models of brain injury such as in vitro Oxygen-Glucose-Deprivation (OGD) and Traumatic Brain Injury (TBI), as well as in vivo Middle Cerebral Artery Occlusion (MCAO) have largely demonstrated positive neuroprotective behavior. On the other hand, some warning has been made to potential negative effects of argon treatments in cases of ischemic brain injury, where increases of damage in the sub-cortical region of the brain have been uncovered. Further support for argon use in the medical field has been demonstrated in its use in combination with tPA, its ability as an organoprotectant, and its surgical applications. This review seeks to summarize the history and development of argon gas use in medical research as mainly a neuroprotective agent, to summarize the mechanisms associated with its biological effects, and to elucidate its future potential.

Doxorubicin-induced death in tumour cells and cardiomyocytes: is autophagy the key to improving future clinical outcomes?

Objectives

Doxorubicin, a commonly used frontline chemotherapeutic agent for cancer, is not without side-effects. The original thinking that the drug causes necrosis in tumours has largely given way to its link with apoptosis over the past two decades.

Key findings

More recently, major biomarkers such as AMPK, p53 and Bcl-2 have been identified as important to apoptosis induction by doxorubicin. It is Bcl-2 and its interaction with Beclin-1 that has refocussed research attention on doxorubicin, albeit this time for its ability to induce autophagy. Autophagy can be either anticancerous or procancerous however, so it is critical that the reasons for which cancer cells undergo this type of cell biological event be clearly identified for future exploitation.

Summary

Taking a step back from treating patients with large doses of doxorubicin, which causes toxicity to the heart amongst other organs, and further research with this drug's molecular signalling in not only neoplastic but normal cells, may indeed redefine the way doxorubicin is used clinically and potentially lead to better neoplastic disease management.

Bax and Bak function as the outer membrane component of the mitochondrial permeability pore in regulating necrotic cell death in mice

A critical event in ischemia-based cell death is the opening of the mitochondrial permeability transition pore (MPTP). However, the molecular identity of the components of the MPTP remains unknown. Here, we determined that the Bcl-2 family members Bax and Bak, which are central regulators of apoptotic cell death, are also required for mitochondrial pore-dependent necrotic cell death by facilitating outer membrane permeability of the MPTP. Loss of Bax/Bak reduced outer mitochondrial membrane permeability and conductance without altering inner membrane MPTP function, resulting in resistance to mitochondrial calcium overload and necrotic cell death. Reconstitution with mutants of Bax that cannot oligomerize and form apoptotic pores, but still enhance outer membrane permeability, permitted MPTP-dependent mitochondrial swelling and restored necrotic cell death. Our data predict that the MPTP is an inner membrane regulated process, although in the absence of Bax/Bak the outer membrane resists swelling and prevents organelle rupture to prevent cell death.

DOI:http://dx.doi.org/10.7554/eLife.00772.001

In all multicellular plants and animals, cells are continuously dying and being replaced. There are a number of different types of cell death, but two of the best studied are apoptosis and necrosis. Apoptosis, sometimes referred to as ‘cell suicide’, is a form of programmed cell death that is generally beneficial to the organism. Necrosis, however, occurs whenever cells are damaged—for example, due to a lack of oxygen—and can trigger harmful inflammation in surrounding tissue. Although the processes leading up to apoptosis and necrosis are very different, they both involve regulated changes in mitochondria—the organelles that supply cells with chemical energy.

Mitochondria have a distinctive appearance, being enclosed by two membranes, the innermost of which is highly folded. During apoptosis, large pores form in the outer membranes of mitochondria. These pores are generated by two proteins—Bax and Bak—and they enable the mitochondrion to release proteins that activate processes involved in apoptosis. Pores also form in the mitochondrial membrane during necrosis. However, these mitochondrial permeability transition pores (MPTPs) occur simultaneously in both the inner and outer membranes and are thought to lead to swelling and rupture of mitochondria.

Now, Karch et al. have shown that Bax and Bak are also involved in the formation of these permeability pores that underlie necrosis. When mouse cells that had been genetically modified to lack Bak and Bax were grown in cell culture, they were found to be resistant to substances that normally induce necrosis. Instead, their mitochondria continued to function normally, suggesting that MPTPs cannot form in the absence of Bak and Bax.

Karch et al. then generated mice with heart cells that lack Bax and Bak, and deprived their hearts of oxygen to simulate a heart attack. Compared to normal mice, the genetically modified animals experienced less damage to their heart muscle, suggesting that the absence of Bax and Bak prevents cell death due to necrosis. If Bax and Bak are involved in both apoptosis and necrosis, inhibiting them could be a powerful therapeutic approach for preventing all forms of cell death during heart attacks or in certain degenerative diseases.

DOI:http://dx.doi.org/10.7554/eLife.00772.002

Molecular mechanisms of the antitumor activity of SB225002: a novel microtubule inhibitor

SB225002 (SB) is an IL-8 receptor B (IL-8RB) antagonist that has previously been shown to inhibit IL-8-based cancer cell invasion, and to possess in vivo anti-inflammatory and anti-nociceptive effects. The present study presented an evidence for the cell cycle-targeting activity of SB in a panel of p53-mutant human cancer cell lines of different origin, and investigated the underlying molecular mechanisms. A combination of cell cycle analysis, immunocytometry, immunoblotting, and RNA interference revealed that SB induced a BubR1-dependent mitotic arrest. Mechanistically, SB was shown to possess a microtubule destabilizing activity evidenced by hyperphosphorylation of Bcl2 and BclxL, suppression of microtubule polymerization and induction of a prometaphase arrest. Molecular docking studies suggested that SB has a good affinity toward vinblastine-binding site on β-tubulin subunit. Of note, SB265610 which is a close structural analog of SB225002 with a potent IL-8RB antagonistic activity did not exhibit a similar antimitotic activity. Importantly, in P-glycoprotein overexpressing NCI/Adr-Res cells the antitumor activity of SB was unaffected by multidrug resistance. Interestingly, the mechanisms of SB-induced cell death were cell-line dependent, where in invasive hepatocellular carcinoma HLE cells the significant contribution of BAK-dependent mitochondrial apoptosis was demonstrated. Conversely, SB activated p38 MAPK signaling in colorectal adenocarcinoma cells SW480, and pharmacologic inhibition of p38 MAPK activity revealed its key role in mediating SB-induced caspase-independent cell death. In summary, the present study introduced SB as a promising antitumor agent which has the potential to exert its activity through dual mechanisms involving microtubules targeting and interference with IL-8-drivin cancer progression.

miR-125b develops chemoresistance in Ewing sarcoma/primitive neuroectodermal tumor

Background

Diverse functions of microRNAs (miRNAs), including effects on tumorigenesis, proliferation, and differentiation, have been reported, and several miRNAs have also been demonstrated to play an important role in apoptosis. In this study, we investigated the possible role that miRNAs may play in the development of chemoresistance in Ewing sarcoma/primitive neuroectodermal tumor (EWS).

Methods

We screened doxorubicin (Dox)-resistant EWS cells to identify any distinct miRNA sequences that may regulate the chemoresistance of EWS cells. The effects of miRNAs were evaluated using a chemosensitivity assay. The possible target genes of the miRNAs were predicted using a web-based prediction program.

Results

We found miR-125b to be upregulated in two different Dox-resistant EWS cell lines. The upregulation of miR-125b was also confirmed in the EWS tumors having survived chemotherapy regimen which includes doxorubicin. When miR-125b was knocked down in EWS cells, both the Dox-resistant and parental cells showed an enhanced sensitivity to doxorubicin, which was associated with the upregulation of the pro-apoptotic molecules, p53 and Bak. Inversely, the overexpression of miR-125b in parental EWS cells resulted in enhanced drug resistance, not only to doxorubicin, but also to etoposide and vincristine.

Conclusions

Our findings suggest that miR-125b may play a role in the development of chemoresistance in EWS by suppressing the expression of the apoptotic mediators, such as p53 and Bak.

PI3K inhibition potentiates Bcl-2-dependent apoptosis in renal carcinoma cells

Inhibitors of PI3-K/Akt are currently being assessed clinically in patients with advanced RCC. Identification of therapeutic strategies that might enhance the efficacy of PI3-K/Akt inhibitors is therefore of great interest. As PI3-K inhibition would be expected to have many pro-apoptotic effects, we hypothesized that there may be unique synergy between PI3-K inhibitors and BH3-mimetics. Towards this end, we assessed the combination of the PI3K inhibitor LY 294002 and the Bcl-2 family inhibitor ABT-737 in RCC cell lines. We found that the combinatorial treatment with these agents led to a significant increase in PARP cleavage and cell death in all RCC cell lines. The synergized cell death was correlated with decreased levels of Mcl-1 and XIAP, and increased levels in Bim, and appears critically dependent upon the activation of caspase 3 and 8. The enhanced lethality observed with the combination also appears dependent upon the regulation of XIAP, Mcl-1 and Bim levels. Our results suggest that the combination of PI3-K inhibitors with BH3-mimetics may be a viable therapeutic strategy in RCC.

Increased neuronal apoptosis in medial prefrontal cortex is accompanied with changes of Bcl-2 and Bax in a rat model of post-traumatic stress disorder

Post-traumatic stress disorder (PTSD) is an anxiety disorder caused by traumatic experience, which affects a patient's quality of life and social stability. The objective of this study was to determine the apoptosis-related genes B-cell lymphoma 2 (Bcl-2) and BCL2-associated X (Bax) expressions and medial prefrontal cortex (mPFC) neuronal apoptosis after PTSD in rat model and therefore to provide experimental evidence to reveal PTSD pathogenesis. The single-prolonged stress (SPS) method was used to set up the rat PTSD models. Chemiluminescence was used to determine serum corticosterone levels. Neuronal apoptosis was detected using transmission electron microscopy, Hoechst staining, and terminal deoxynucleotidyl transferase dUTP nick end labeling staining. Immunohistochemistry, immunofluorescence, RT-PCR, and Western blot were used to detect the expressions of Bcl-2 and Bax protein in mPFC. Our results showed an increased mPFC neuronal apoptosis after SPS stimulation. The number of apoptotic cells peaked on day 7. The expressions of Bcl-2 and Bax peaked on days 4 and 7. The Bcl-2/Bax ratio elevated on days 1 and 4 but decreased markedly on day 7. These results indicated that SPS stimulation increased the number of apoptotic neurons, up-regulated the expressions of Bcl-2 and Bax, and altered the Bcl-2/Bax ratio in the mPFC of PTSD rats.

Sorafenib has potent antitumor activity against multiple myeloma in vitro, ex vivo, and in vivo in the 5T33MM mouse model

Multiple myeloma (MM) is a B-cell malignancy characterized by the expansion of clonal plasma blasts/plasma cells within the bone marrow that relies on multiple signaling cascades, including tyrosine kinase activated pathways, to proliferate and evade cell death. Despite emerging new treatment strategies, multiple myeloma remains at present incurable. Thus, novel approaches targeting several signaling cascades by using the multi-tyrosine kinase inhibitor (TKI), sorafenib, seem a promising treatment approach for multiple myeloma. Here, we show that sorafenib induces cell death in multiple myeloma cell lines and in CD138(+)-enriched primary multiple myeloma patient samples in a caspase-dependent and -independent manner. Furthermore, sorafenib has a strong antitumoral and -angiogenic activity in the 5T33MM mouse model leading to increased overall survival. Multiple myeloma cells undergo autophagy in response to sorafenib, and inhibition of this cytoprotective pathway potentiated the efficacy of this TKI. Mcl-1, a survival factor in multiple myeloma, is downregulated at the protein level by sorafenib allowing for the execution of cell death, as ectopic overexpression of this protein protects multiple myeloma cells. Concomitant targeting of Mcl-1 by sorafenib and of Bcl-2/Bcl-xL by the antagonist ABT737 improves the efficacy of sorafenib in multiple myeloma cell lines and CD138(+)-enriched primary cells in the presence of bone marrow stromal cells. Altogether, our data support the use of sorafenib as a novel therapeutic modality against human multiple myeloma, and its efficacy may be potentiated in combination with ABT737.

Glucocorticoid resistance in chronic lymphocytic leukaemia is associated with a failure of upregulated Bim/Bcl-2 complexes to activate Bax and Bak

Glucocorticoids (GCs) represent an important component of modern treatment regimens for fludarabine-refractory or TP53-defective chronic lymphocytic leukemia (CLL). However, GC therapy is not effective in all patients. The molecular mechanisms responsible for GC-induced apoptosis and resistance were therefore investigated in primary malignant cells obtained from a cohort of 46 patients with CLL. Dexamethasone-induced apoptosis was unaffected by p53 dysfunction and more pronounced in cases with unmutated IGHV genes. Cross-resistance was observed between dexamethasone and other GCs but not fludarabine, indicating non-identical resistance mechanisms. GC treatment resulted in the upregulation of Bim mRNA and protein, but to comparable levels in both GC-resistant and sensitive cells. Pre-incubation with Bim siRNAs reduced GC-induced upregulation of Bim protein and conferred resistance to GC-induced apoptosis in previously GC-sensitive cells. GC-induced upregulation of Bim was associated with the activation of Bax and Bak in GC-sensitive but not -resistant CLL samples. Co-immunoprecipitation experiments showed that Bim does not interact directly with Bax or Bak, but is almost exclusively bound to Bcl-2 regardless of GC treatment. Taken together, these findings suggest that the GC-induced killing of CLL cells results from the indirect activation of Bax and Bak by upregulated Bim/Bcl-2 complexes, and that GC resistance results from the failure of such activation to occur.

Melatonin potentiates chemotherapy-induced cytotoxicity and apoptosis in rat pancreatic tumor cells

Melatonin has antitumor activity via several mechanisms including its antiproliferative and proapoptotic effects in addition to its potent antioxidant action. Thus, melatonin has proven useful in the treatment of tumors in association with chemotherapeutic drugs. This study was performed to evaluate the effect of melatonin on the cytotoxicity and apoptosis induced by three different chemotherapeutic agents, namely 5-fluorouracil (5-FU), cisplatin, and doxorubicin in the rat pancreatic tumor cell line AR42J. We found that both melatonin and the three chemotherapeutic drugs induce a time-dependent decrease in AR42J cell viability, reaching the highest cytotoxic effect after 48 hr of incubation. Furthermore, melatonin significantly augmented the cytotoxicity of the chemotherapeutic agents. Consistently, cotreatment of AR42J cells with each of the chemotherapeutic agents in the presence of melatonin increased the population of apoptotic cells, elevated mitochondrial membrane depolarization, and augmented intracellular reactive oxygen species (ROS) production compared to treatment with each chemotherapeutic agent alone. These results provide evidence that in vitro melatonin enhances chemotherapy-induced cytotoxicity and apoptosis in rat pancreatic tumor AR42J cells and, therefore, melatonin may be potentially applied to pancreatic tumor treatment as a powerful synergistic agent in combination with chemotherapeutic drugs.

Enhanced apoptosis of ovarian cancer cells via nanocarrier-mediated codelivery of siRNA and doxorubicin

A folate conjugated ternary copolymer, FA–PEG–PEI–PCL, of poly(ethylene glycol) (PEG), poly(ethylene imine) (PEI), and poly(ɛ-caprolactone) (PCL) was synthesized. The copolymer self-assembled into cationic micelles capable of co-delivering siRNA and the anticancer drug doxorubicin (DOX). This dual functional nanocarrier demonstrated low cytotoxicity and high performance in drug/siRNA delivery. Upon the codelivery of siRNA, targeting the Bcl-2 gene, and DOX, using the folate-targeted nanocarrier, DOX-induced apoptosis in the skov-3 cells overexpressing folate receptor was significantly enhanced through a mechanism of downregulating the antiapoptotic protein Bcl-2, while simultaneously upregulating the proapoptotic protein Bax. This work suggested that the combination of Bcl-2 siRNA and DOX therapies is feasible, based on our dual functional nanocarrier, which set up a good basis for a future in vivo test.

Targeting of distinct signaling cascades and cancer-associated fibroblasts define the efficacy of Sorafenib against prostate cancer cells

Sorafenib, a multi-tyrosine kinase inhibitor, kills more effectively the non-metastatic prostate cancer cell line 22Rv1 than the highly metastatic prostate cancer cell line PC3. In 22Rv1 cells, constitutively active STAT3 and ERK are targeted by sorafenib, contrasting with PC3 cells, in which these kinases are not active. Notably, overexpression of a constitutively active MEK construct in 22Rv1 cells stimulates the sustained phosphorylation of Bad and protects from sorafenib-induced cell death. In PC3 cells, Src and AKT are constitutively activated and targeted by sorafenib, leading to an increase in Bim protein levels. Overexpression of constitutively active AKT or knockdown of Bim protects PC3 cells from sorafenib-induced killing. In both PC3 and 22Rv1 cells, Mcl-1 depletion is required for the induction of cell death by sorafenib as transient overexpression of Mcl-1 is protective. Interestingly, co-culturing of primary cancer-associated fibroblasts (CAFs) with 22Rv1 or PC3 cells protected the cancer cells from sorafenib-induced cell death, and this protection was largely overcome by co-administration of the Bcl-2 antagonist, ABT737. In summary, the differential tyrosine kinase profile of prostate cancer cells defines the cytotoxic efficacy of sorafenib and this profile is modulated by CAFs to promote resistance. The combination of sorafenib with Bcl-2 antagonists, such as ABT737, may constitute a promising therapeutic strategy against prostate cancer.

Anticancer activity of S-allylmercapto-L-cysteine on implanted tumor of human gastric cancer cell

Allylmercapto glutathione S-conjugate, S-allylmercapto-L-cysteine (SAMC), which is biotransformed from allyl sulfides and from naturally occurring water-soluble garlic derivatives, has been known to inhibit tumorigenesis. We found that SAMC was able to induce apoptosis in gastric cancer cells in vitro. We report that SAMC inhibited tumor growth rate by 31.36% and 37.78% at doses of 100 and 300 mg/kg, respectively. Apoptosis in the implanted tumor cells was manifested by apoptotic characteristics, including morphological changes of chromatin crescent, cell shrinkage and membrane blebbing. The apoptosis index of 100 mg/kg and 300 mg/kg of SAMC was 20.74 ± 2.50% and 30.61 ± 2.42%, respectively, by terminal deoxy-nucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) nick-end labeling (TUNEL) staining. The positive rate of B-cell lymphoma 2 (bcl-2) protein expression of control, 100 mg/kg SAMC and 300 mg/kg SAMC was 15.20 ± 1.67%, 10.94 ± 1.57%, and 8.24 ± 1.07%, respectively, by immunohistochemical staining. The positive rate of bax protein expression of control, 100 mg/kg SAMC and 300 mg/kg SAMC was 15.30 ± 1.90%, 23.18 ± 1.81%, and 25.26 ± 3.03%, respectively. We also observed decreases in bcl-2 mRNA and increases in bax mRNA by SAMC in a dose-dependent manner by reverse transcription-polymerase chain reaction (RT-PCR). These results suggest that SAMC may regulate bcl-2 and bax to induce apoptosis in transplanted tumor cells.

Engineered nanostructural materials for application in cancer biology and medicine

Nanotechnology covers a wide variety of fields of research, including chemistry, physics, biology and medicine, with extensive applications in cancer, ranging from accurate, early detection of malignant lesions to minimizing metastasis. Continued development of cancer-targeted therapy has promising advantages: maximizing the effectiveness of anticancer drugs while decreasing the harmful systemic effects; tumor destruction via heating that takes advantage of magnetic nanoparticles' size, magnetization and biocompatibility; novel drug-delivery systems; and gene therapy functions to facilitate controlled drug loading and release inside the cytoplasm. These and other nanotechnology applications can contribute essential new knowledge in the fight against cancer.

Glucocorticoid-induced cell death is mediated through reduced glucose metabolism in lymphoid leukemia cells

Malignant cells are known to have increased glucose uptake and accelerated glucose metabolism. Using liquid chromatography and mass spectrometry, we found that treatment of acute lymphoblastic leukemia (ALL) cells with the glucocorticoid (GC) dexamethasone (Dex) resulted in profound inhibition of glycolysis. We thus demonstrate that Dex reduced glucose consumption, glucose utilization and glucose uptake by leukemic cells. Furthermore, Dex treatment decreased the levels of the plasma membrane-associated glucose transporter GLUT1, thus revealing the mechanism for the inhibition of glucose uptake. Inhibition of glucose uptake correlated with induction of cell death in ALL cell lines and in leukemic blasts from ALL patients cultured ex vivo. Addition of di-methyl succinate could partially overcome cell death induced by Dex in RS4;11 cells, thereby further supporting the notion that inhibition of glycolysis contributes to the induction of apoptosis. Finally, Dex killed RS4;11 cells significantly more efficiently when cultured in lower glucose concentrations suggesting that modulation of glucose levels might influence the effectiveness of GC treatment in ALL. In summary, our data show that GC treatment blocks glucose uptake by leukemic cells leading to inhibition of glycolysis and that these effects play an important role in the induction of cell death by these drugs.

Resveratrol induces apoptosis of human nasopharyngeal carcinoma cells via activation of multiple apoptotic pathways

Resveratrol, a naturally occurring dietary compound with chemopreventive properties has been reported to trigger a variety of cancer cell types to apoptosis. Whether resveratrol shows any activity on human nasopharyngeal carcinoma (NPC) cells remained to be determined. The aim of this study was to investigate the effect and mechanism of resveratrol on human NPC cells. Treatment of resveratrol resulted in significant decrease in cell viability of NPC cell lines in a dose- and time-dependent manner. A dose-dependent apoptotic cell death was also measured by flow cytometery analysis. Molecular mechanistic studies of apoptosis unraveled resveratrol treatment resulted in a significant loss of mitochondrial transmembrane potential, release of cytochrome c, enhanced expression of Fas ligand (FasL), and suppression of glucose-regulated protein 78 kDa (GRP78). These were followed by activation of caspases-9, -8, -4, and -3, subsequently leading to DNA fragmentation and cell apoptosis. Furthermore, up-regulation of proapoptotic Bax and down-regulation of antiapoptotic Bcl-2 protein were also observed. Taken together, resveratrol induces apoptosis in human NPC cells through regulation of multiple apoptotic pathways, including death receptor, mitochondria, and endoplasmic reticulum (ER) stress. Resveratrol can be developed as an effective compound for human NPC treatment.

Aven blocks DNA damage-induced apoptosis by stabilising Bcl-xL

Induction of apoptosis by DNA-damaging agents involves the activation of mitochondrial apoptotic pathway. Aven has been identified as an antiapoptotic protein and has been shown to activate ATM in response to DNA damage. In this study, we demonstrated that enforced expression of Aven blocks UV-irradiation-, SN-38- or cisplatin-induced apoptosis upstream of mitochondria by stabilising Bcl-xL protein levels in breast cancer cells. Aven silencing by RNA interference markedly enhanced apoptotic response following treatment with DNA-damaging agents. Aven is complexed with Bcl-xL in untreated breast cancer cells and treatment with DNA-damaging agents led to decreased Aven/Bcl-xL interaction. Importantly, Bcl-xL was necessary for the prosurvival activity of Aven and depletion of Bcl-xL abrogated Aven-mediated protection against DNA damage-induced apoptosis. Analysis of breast cancer tissue microarrays revealed decreased Aven nuclear expression in breast cancer tissues compared with non-neoplastic breast tissues. In particular, we detected reduced nuclear expression of Aven in infiltrating ductal carcinoma and papillary carcinoma breast cancer subtypes compared with non-neoplastic breast tissues and infiltrating lobular breast cancer tissues. Our results suggest that Aven is an important mediator in DNA damage-induced apoptotic signalling in breast cancer cells and its nuclear expression is altered in breast cancer tissues, which may contribute to genomic instability in breast cancer tumours.

Doxorubicin and etoposide sensitize small cell lung carcinoma cells expressing caspase-8 to TRAIL

BACKGROUND

TRAIL is considered as a promising anti-cancer agent, because of its ability to induce apoptosis in cancer but not in most normal cells. However, growing evidence exist that many cancer cells are resistant to its apoptotic effects. SCLC is a typical example of tumor entity where TRAIL monotherapy is not efficient.

RESULTS

We demonstrated that doxorubicin and etoposide markedly sensitized SCLC cells expressing caspase-8 to apoptotic effects of TRAIL. The drug-mediated sensitization of these cells was associated with increase of surface and total DR5 protein level, specific cleavage of cFLIPL, decrease of cFLIPS level, and a strong activation of caspase-8. The involvement of mitochondria-mediated pathway was demonstrated by enhanced Bid cleavage, Bax activation, and cytochrome c release. Activation of caspase-8 induced by combined treatment was shown to occur upstream of mitochondria and effector caspases.

CONCLUSIONS

Our results highlight significant applicability of doxorubicin and etoposide in sensitization of SCLC cells expressing caspase-8 to treatment with TRAIL.

Different contribution of BH3-only proteins and caspases to doxorubicin-induced apoptosis in p53-deficient leukemia cells

Bcl-2 family proteins are key regulators of the intrinsic apoptotic pathway, either facilitating (Bax, Bak, BH3-only) or inhibiting (Bcl-2, Bcl-x(L), Mcl-1, A1) mitochondrial release of apoptogenic factors. The role of caspases in this process is a matter of controversy. We have analyzed the relative contribution of caspases and Bcl-2 family of proteins in the induction phase of apoptosis triggered by doxorubicin in two p53-deficient leukemia cell lines, Jurkat and U937. First, we have found that caspases are dispensable for the induction phase of doxorubicin-induced apoptosis in both cell lines but they are needed to speed up the execution phase in Jurkat cells, not expressing Bax. Thus, down-regulation of Bak expression by siRNA significantly prevented doxorubicin-induced apoptosis in Jurkat but not in U937 cells. Reduction of Mcl-1 protein levels with siRNA increased sensitivity to apoptosis in both cell lines. Moreover, our results indicate that the contribution of BH3-only proteins to apoptosis is cell line specific. In Jurkat cells simultaneous silencing of Bim and PUMA was necessary to reduce doxorubicin-induced apoptosis. In U937 cells silencing of Bim or Noxa reduced sensitivity to doxorubicin. Immunoprecipitation experiments discarded an interaction between Mcl-1 and Bak in both cell lines and underscored the role of Bim and PUMA as mediators of Bax/Bak activation.

Erucylphospho-N,N,N-trimethylpropylammonium (erufosine) is a potential antimyeloma drug devoid of myelotoxicity

PURPOSE

Erufosine is an i.v. injectable alkylphosphocholine which is active against various haematological malignancies in vitro. In the present study, its effects on multiple myeloma (MM) cell lines and on murine and human hematopoietic progenitor cells (HPCs) were investigated.

METHODS

The following MM cell lines were used: RPMI-8226, U-266 and OPM-2. The cytotoxicity of erufosine against these cell lines was determined by the MTT-dye reduction assay. Bcl-2, Bcl-X(L) and pAkt expression levels, activation of caspases, as well as cleavage of PARP, were studied by Western blotting. Migration was evaluated by a modified Boyden-chamber assay. The haematologic toxicity of erufosine was assessed using clonogenicity assays with normal HPCs of murine or human origin.

RESULTS

Significant cytotoxic activity of erufosine against the MM cell lines was found. Comparison of the characteristics of erufosine-induced cell death in the three cell lines revealed a complex mode of action with apoptotic mechanisms prevailing in OPM-2 cells and non-apoptotic mechanisms prevailing in U-266 cells. The sensitivity of the MM cell lines to erufosine-induced apoptosis correlated inversely with the Bcl-X(L) expression level. Erufosine participated in synergistic interactions with various drugs. Furthermore, it showed potent migration-inhibiting activity in RPMI-8226 cells. Erufosine was not toxic to normal HPCs of murine or human origin and even stimulated progenitors from human umbilical cord blood to form granulocyte/macrophage colonies. Moreover, erufosine ameliorated the toxicity of bendamustine to murine HPCs.

CONCLUSIONS

Overall, the data presented reveal that erufosine could have potential as an antimyeloma drug and deserves further development.