Anticancer and chemosensitizing effects of 2,3-DCPE in ovarian carcinoma cell lines: link with ERK activation and modulation of p21WAF1/CIP1, Bcl-2 and Bcl-xL expression

Flavonoids Restore Platinum Drug Sensitivity to Ovarian Carcinoma Cells in a Phospho-ERK1/2-Dependent Fashion

Ovarian cancer (OC) is the second most common type of gynecological malignancy; it has poor survival rates and is frequently (>75%) diagnosed at an advanced stage. Platinum-based chemotherapy, with, e.g., carboplatin, is the standard of care for OC, but toxicity and acquired resistance to therapy have proven challenging. Despite advances in OC diagnosis and treatment, approximately 85% of patients will experience relapse, mainly due to chemoresistance. The latter is attributed to alterations in the cancer cells and is also mediated by tumor microenvironment (TME). Recently, we reported the synthesis of a platinum (IV) prodrug that exhibits equal potency toward platinum-sensitive and resistant OC cell lines. Here, we investigated the effect of TME on platinum sensitivity. Co-culture of OC cells with murine or human mesenchymal stem cells (MS-5 and HS-5, respectively) rendered them resistant to chemotherapeutic agents, including platinum, paclitaxel and colchicine. Platinum resistance was also conferred by co-culture with differentiated murine adipocyte progenitor cells. Exposure of OC cells to chemotherapeutic agents resulted in activation of phospho-ERK1/2. Co-culture with MS-5, which conferred drug resistance, was accompanied by blockage of phospho-ERK1/2 activation. The flavonoids fisetin and quercetin were active in restoring ERK phosphorylation, as well as sensitivity to platinum compounds. Exposure of OC cells to cobimetinib-a MEK1 inhibitor that also inhibits extracellular signal-regulated kinase (ERK) phosphorylation-which resulted in reduced sensitivity to the platinum compound. This suggests that ERK activity is involved in mediating the function of flavonoids in restoring platinum sensitivity to OC co-cultured with cellular components of the TME. Our data show the potential of combining flavonoids with standard therapy to restore drug sensitivity to OC cells and overcome TME-mediated platinum drug resistance.

Evaluation of the potential of a new ribavirin analog impairing the dissemination of ovarian cancer cells

Epithelial ovarian cancers are insidious pathologies that give a poor prognosis due to their late discovery and the increasing emergence of chemoresistance. Development of small pharmacological anticancer molecules remains a major challenge. Ribavirin, usually used in the treatment of hepatitis C virus infections and more recently few cancers, has been a suggestion. However, Ribavirin has many side-effects, suggesting that the synthesis of analogs might be more appropriate. We have investigated the effect of a Ribavirin analog, SRO-91, on cancer cell behavioral characteristics considered as some of the hallmarks of cancer. Two human ovarian adenocarcinoma cell lines (SKOV3 and IGROV1) and normal cells (mesothelial and fibroblasts) have been used to compare the effects of SRO-91 with those of Ribavirin on cell behavior underlying tumor cell dissemination. SRO-91, like Ribavirin, inhibits proliferation, migration, clonogenicity and spheroids formation of cancer cells. Unlike Ribavirin, SRO-91 is preferentially toxic to cancer compared with normal cells. An in vitro physiologically relevant model showed that SRO-91, like Ribavirin or cisplatin, inhibits cancer cell implantation onto peritoneal mesothelium. In conclusion, SRO-91 analog effects on tumor dissemination and its safety regarding non-cancerous (normal) cells are encouraging findings a promising drug for the treatment of ovarian cancer.

Co-delivery of carboplatin and paclitaxel via cross-linked multilamellar liposomes for ovarian cancer treatment

Cross-linked multilamellar liposomes offer an approach to achieve combinatorial delivery of hydrophobic paclitaxel and hydrophilic metallic carboplatin at a synergistic ratio to treat ovarian cancer.

Carboplatin (CPT) and paclitaxel (PTX) used in combination is one of the most effective treatments for ovarian cancer. However, the traditional combination methods used to co-administrate CPT and PTX showed limited clinical efficacy due to their distinct pharmacokinetics. Although much effort has been devoted to developing nanoparticles capable of encapsulating drugs with different lipophilicites, co-delivery of carboplatin with paclitaxel by a single nanoparticle has rarely been reported. Here, we encapsulated and delivered this drug combination to ovarian cancer cells at a controlled ratio by a previously reported crosslinked multilamellar liposome vesicle (cMLV). A 1 : 1 CPT/PTX molar ratio for cMLVs (CPT/PTX) combination treatment was found to induce the strongest anti-tumor synergism and to target ALDH+ cancer stem cells (CSC) in vitro. Moreover, we demonstrated that this co-encapsulation strategy reduced systemic cytotoxicity and resulted in a stronger anti-tumor effect when compared to free drug combinations and individual drug-loaded cMLVs in an OVCAR8 ovarian cancer xenograft mouse model. Thus, this study suggests a potentially promising combination therapy for ovarian cancer in clinical practice.

Ascites-induced shift along epithelial-mesenchymal spectrum in ovarian cancer cells: enhancement of their invasive behavior partly dependant on αv integrins

At least one-third of patients with epithelial ovarian cancer (OC) present ascites at diagnosis and almost all have ascites at recurrence. The presence of ascites, which acts as a dynamic reservoir of active molecules and cellular components, correlates with the OC peritoneal metastasis and is associated with poor prognosis. Since epithelial-mesenchymal transition (EMT) is involved in different phases of OC progression, we have investigated the effect of the unique ascitic tumor microenvironment on the EMT status and the behavior of OC cells. The exposure of three OC cell lines to ascites leads to changes in cellular morphologies. Within ascites, OC cells harboring an initial intermediate epithelial phenotype are characterized by marked dislocation of epithelial markers (E-cadherin, ZO-1 staining) while OC cells initially harboring an intermediate mesenchymal phenotype strengthen their mesenchymal markers (N-cadherin, vimentin). Ascites differentially triggers a dissemination phenotype related to the initial cell features by either allowing the proliferation and the formation of spheroids and the extension of colonies for cells that present an initial epithelial intermediate phenotype, or favoring the migration of cells with a mesenchymal intermediate phenotype. In an ascitic microenvironment, a redeployment of αv integrins into cells was observed and the ascites-induced accentuation of the two different invasive phenotypes (i.e. spheroids formation or migration) was shown to involve αv integrins. Thus, ascites induces a shift toward an unstable intermediate state of the epithelial-mesenchymal spectrum and confers a more aggressive cell behavior that takes on a different pathway based on the initial epithelial-mesenchymal cell features.

A cell-based screening platform identifies novel mosquitocidal toxins

Pesticides currently in widespread use often lack species specificity and also become less effective as resistance emerges. Consequently, there is a pressing need to develop novel agents that are narrowly targeted and safe to humans. A cell-based screening platform was designed to discover compounds that are lethal to mosquito (Anopheles and Aedes) cells but show little or no activity against other insect (Drosophila) or human cell lines. Mosquito-specific, aqueous-stable cytotoxins were recovered at rare frequencies. Three of these were profiled for structure-activity relationships and also assessed in whole-animal toxicity assays. In at least one test case, species-specific cytotoxicity seen in culture effectively translated to the whole-animal level, with potent toxicity against Anopheles yet none against Drosophila. Therefore, this initiative has the potential to advance novel mosquitocidal agents and, in a broader sense, could establish a versatile platform for developing customized pesticides that selectively target other disease vectors as well.

ERK inhibition enhances TSA-induced gastric cancer cell apoptosis via NF-κB-dependent and Notch-independent mechanism

AIMS

To analyze the combined impact of the histone deacetylase inhibitor (HDACI) Trichostatin A (TSA) and the extracellular-signal-regulated kinase 1/2 (ERK1/2) inhibitor PD98059 on gastric cancer (GC) cell line SGC7901 growth.

MAIN METHODS

SGC7901 cells were treated with TSA, PD98059 or with a TSA-PD98059 combination. Effects of drug treatment on tumor cell proliferation, apoptosis, cell cycle progression, and cell signaling pathways were investigated by MTS assay, flow cytometry, Western blotting, chromatin immunoprecipitation (ChIP) assay, electrophoretic mobility shift assay (EMSA), and luciferase reporter assay, respectively.

KEY FINDINGS

PD98059 enhanced TSA-induced cell growth arrest, apoptosis and activation of p21(WAF1/CIP1), but reversed TSA-induced activation of ERK1/2 and nuclear factor-κB (NF-κB). TSA alone up-regulated Notch1 and Hes1, and down-regulated Notch2, but PD98059 did not affect the trends of Notch1 and Notch2 induced by TSA. Particularly, PD98059 did potentiate the ability of TSA to down-regulate phospho-histone H3 protein, but increased levels of the acetylated forms of histone H3 bound to the p21(WAF1/CIP1) promoter, leading to enhanced expression of p21(WAF1/CIP1) in SGC7901 cells.

SIGNIFICANCE

PD98059 synergistically potentiates TSA-induced GC growth arrest and apoptosis by manipulating NF-κB and p21(WAF1/CIP1) independent of Notch. Therefore, concomitant administration of HDACIs and ERK1/2 inhibitors may be a promising treatment strategy for individuals with GC.

PKC Signaling is Involved in the Regulation of Progranulin (Acrogranin/PC-Cell-Derived Growth Factor/Granulin-Epithelin Precursor) Protein Expression in Human Ovarian Cancer Cell Lines

Objective

Overexpression of progranulin (also named acrogranin, PC-cell-derived growth factor, or granulin-epithelin precursor) is associated with ovarian cancer, specifically with cell proliferation, malignancy, chemoresistance, and shortened overall survival. The objective of the current study is to identify the signaling pathways involved in the regulation of progranulin expression in ovarian cancer cell lines.

Methods

We studied the relation of protein kinase C (PKC), phosphatidylinositol 3-kinase, protein kinase A, P38, extracellular signal-regulated kinase, and Akt pathways on the modulation of progranulin expression levels in NIH-OVCAR-3 and SK-OV-3 ovarian cancer cell lines. The different pathways were examined using pharmacological inhibitors (calphostin C, LY294002, H89, SB203580, PD98059, and Akt Inhibitor), and mRNA and protein progranulin expression were analyzed by reverse transcriptase polymerase chain reaction and Western blot techniques, respectively.

Results

Inhibition of PKC signal transduction pathway by calphostin C decreased in a dose-dependent manner protein but not mRNA levels of progranulin in both ovarian cancer cell lines. LY294002 but not wortmannin, which are phosphatidylinositol 3-kinase inhibitors, also diminished the expression of progranulin in both cell lines. In addition, LY294002 treatment produced a significant reduction in cell viability. Inhibition of protein kinase A, P38, extracellular signal-regulated kinase, and Akt did not affect progranulin protein expression.

Conclusions

These results suggest that the PKC signaling is involved in the regulation of progranulin protein expression in 2 different ovarian cancer cell lines. Inhibiting these intracellular signal transduction pathways may provide a future therapeutic target for hindering the cellular proliferation and invasion in ovarian cancer produced by progranulin.

Synergistic efficacy of a novel combination therapy controls growth of Bcl-x(L) bountiful neuroblastoma cells by increasing differentiation and apoptosis

Neuroblastoma is the most prevalent extracranial solid tumor mainly in pediatric patients. We explored the efficacy of the combination of 2[(3-[2,3-dichlorophenoxy]propyl)amino]ethanol (2,3-DCPE, a small molecule inhibitor of the anti-apoptotic protein Bcl-x(L)) and N-(4-hydroxyphenyl) retinamide (4-HPR, a synthetic retinoid) in inducing differentiation and apoptosis in human malignant neuroblastoma cells. Immunofluorescence confocal microscopy and flow cytometry showed that the highest level of Bcl-x(L) expression occurred in SK-N-DZ cells followed by SH-SY5Y and IMR-32 cells. Combination of 20 μM 2,3-DCPE and 1 μM 4-HPR acted synergistically in decreasing viability of SK-N-DZ and SH-SY5Y cells. In situ methylene blue staining and protein gel blotting showed the efficacy of this combination of drugs in inducing neuronal differentiation morphologically and also biochemically with upregulation of the neuronal markers such as neurofilament protein (NFP) and neuron specific enolase (NSE) and downregulation of the differentiation inhibiting molecules such as N-Myc and Notch-1 in SK-N-DZ and SH-SY5Y cells. Annexin V-FITC/PI staining showed the synergistic action of this combination therapy in increasing apoptosis in both cell lines. Protein gel blotting manifested that combination therapy increased apoptosis with downregulation of the anti-apoptotic proteins Bcl-x(L), Bcl-2 and Mcl-1 and upregulation of the pro-apoptotic proteins Bax, p53, Puma (p53 upregulated modulator of apoptosis), and Noxa, ultimately causing activation of caspase-3. In conclusion, our results appeared highly encouraging in advocating the use of 2,3-DCPE and 4-HPR as a novel combination therapy for increasing both differentiation and apoptosis in human malignant neuroblastoma cells having Bcl-x(L) overexpression.

Optimized anti-tumor effects of anthracyclines plus Vinca alkaloids using a novel, mechanism-based application schedule

Application of anthracyclines and Vinca alkaloids on the same day represents a hallmark of polychemotherapy protocols for hematopoietic malignancies. Here we show, for the first time, that both drugs might act most efficiently if they are applied on different days. Proof-of-concept studies in 18 cell lines revealed that anthracyclines inhibited cell death by Vinca alkaloids in 83% of cell lines. Importantly, in a preclinical mouse model, doxorubicin reduced the anti-tumor effect of vincristine. Both drugs acted in a sequence-dependent manner and the strongest anti-tumor effect was obtained if both drugs were applied on different days. Most notably for clinical relevance, in 34% of 35 fresh primary childhood leukemia cells tested in vitro, doxorubicin reduced the anti-tumor effect of vincristine. As underlying mechanism, doxorubicin activated p53, p53 induced cell-cycle arrest, and cell-cycle arrest disabled inactivation of antiapoptotic Bcl-2 family members by vincristine; therefore, vincristine was unable to activate downstream apoptosis signaling. As molecular proof, antagonism was rescued by knockdown of p53, whereas knockdown of cyclin A inhibited vincristine-induced apoptosis. Our data suggest evaluating anthracyclines and Vinca alkaloids on different days in future trials. Selecting drug combinations based on mechanistic understanding represents a novel conceptional strategy for potent polychemotherapy protocols.

Lipoplatin formulation review article

Patented platform technologies have been used for the liposomal encapsulation of cisplatin (Lipoplatin) into tumor-targeted 110 nm (in diameter) nanoparticles. The molecular mechanisms, preclinical and clinical data concerning lipoplatin, are reviewed here. Lipoplatin has been successfully administered in three randomized Phase II and III clinical trials. The clinical data mainly include non-small-cell lung cancer but also pancreatic, breast, and head and neck cancers. It is anticipated that lipoplatin will replace cisplatin as well as increase its potential applications. For the first time, a platinum drug has shown superiority to cisplatin, at least in non-squamous non-small-cell lung cancer as reported in a Phase III study which documented a simultaneous lowering of all of the side effects of cisplatin.

Clinical overview on Lipoplatin: a successful liposomal formulation of cisplatin

Nanoparticle formulations for packaging existing drugs have been used to treat cancer. Lipoplatin is a liposomal cisplatin encapsulated into liposome nanoparticles of an average diameter of 110 nm. Lipoplatin has substantially reduced the renal toxicity, peripheral neuropathy, ototoxicity, myelotoxicity as well as nausea/vomiting and asthenia of cisplatin in Phase I, II and III clinical studies with enhanced or similar efficacy to cisplatin. During clinical development, 10- to 200-fold higher accumulation of Lipoplatin in solid tumors compared to adjacent normal tissue was found in patients. Targeting of tumor vasculature by Lipoplatin in animals suggested its antiangiogenesis potential and Lipoplatin was proposed to act like a double-sword: as chemotherapy and an antiangiogenesis drug. Lipoplatin has finished successfully one Phase III non-inferiority clinical study as first-line against NSCLC in its combination with paclitaxel showing statistically significant reduction in nephrotoxicity; two more Phase III studies are in progress, one in NSCLC with gemcitabine also showing noninferiority with reduced toxicity and another in squamous cell carcinoma of the head and neck with 5-fluorouracil. A registrational Phase II/III study against pancreatic cancer is in progress under the orphan drug status granted to Lipoplatin by the European Medicines Agency. Phase II studies are continuing in advanced breast cancer with vinorelbine and gastrointestinal cancers with radiotherapy and 5-fluorouracil. The highlights of the clinical development of Lipoplatin are reviewed.

Gene-expression profiling in epithelial ovarian cancer

DNA-microarray technology has made it possible to simultaneously analyze the expression of thousands of genes in a small sample of tumor tissue. In epithelial ovarian cancer, gene-expression profiling has been used to provide prognostic information, to predict response to first-line platinum-based chemotherapy, and to discriminate between different histologic subtypes. Furthermore, DNA-microarray technology might permit identification of novel markers for early detection of disease and provide insights into the mechanisms of cancer growth and chemotherapy resistance. In this Review, we summarize the contributions of gene-expression profiling to the diagnosis and management of epithelial ovarian cancer and discuss ways in which this technique could become a useful tool in clinical management.