Gef gene therapy enhances the therapeutic efficacy of doxorubicin to combat growth of MCF-7 breast cancer cells

Evaluation of poly (lactic-co-glycolic acid) nanoparticles to improve the therapeutic efficacy of paclitaxel in breast cancer

Introduction: Paclitaxel (PTX) is a cornerstone in the treatment of breast cancer, the most common type of cancer in women. However, this drug has serious limitations, including lack of tissue-specificity, poor water solubility, and the development of drug resistance. The transport of PTX in a polymeric nanoformulation could overcome these limitations. Methods: In this study, PLGA-PTX nanoparticles (NPs) were assayed in breast cancer cell lines, breast cancer stem cells (CSCs) and multicellular tumor spheroids (MTSs) analyzing cell cycle, cell uptake (Nile Red-NR-) and α-tubulin expression. In addition, PLGA-PTX NPs were tested in vivo using C57BL/6 mice, including a biodistribution assay. Results: PTX-PLGA NPs induced a significant decrease in the PTX IC50 of cancer cell lines (1.31 and 3.03-fold reduction in MDA-MB-231 and E0771 cells, respectively) and CSCs. In addition, MTSs treated with PTX-PLGA exhibited a more disorganized surface and significantly higher cell death rates compared to free PTX (27.9% and 16.3% less in MTSs from MCF-7 and E0771, respectively). PTX-PLGA nanoformulation preserved PTX's mechanism of action and increased its cell internalization. Interestingly, PTX-PLGA NPs not only reduced the tumor volume of treated mice but also increased the antineoplastic drug accumulation in their lungs, liver, and spleen. In addition, mice treated with PTX-loaded NPs showed blood parameters similar to the control mice, in contrast with free PTX. Conclusion: These results suggest that our PTX-PLGA NPs could be a suitable strategy for breast cancer therapy, improving antitumor drug efficiency and reducing systemic toxicity without altering its mechanism of action.

The Antitumor Activity of Sodium Selenite Alone and in Combination with Gemcitabine in Pancreatic Cancer: An In Vitro and In Vivo Study

Sodium selenite acts by depleting enzymes that protect against cellular oxidative stress. To determine its effect alone or in combination with gemcitabine (GMZ) in pancreatic cancer, we used PANC-1 and Pan02 cell lines and C57BL mice bearing a Pan02-generated tumor. Our results demonstrated a significant inhibition of pancreatic cancer cell viability with the use of sodium selenite alone and a synergistic effect when associated with GMZ. The molecular mechanisms of the antitumor effect of sodium selenite alone involved apoptosis-inducing factor (AIF) and the expression of phospho-p38 in the combined therapy. In addition, sodium selenite alone and in association with GMZ significantly decreased the migration capacity and colony-forming ability, reduced tumor activity in multicellular tumor spheroids (MTS) and decreased sphere formation of cancer stem cells. In vivo studies demonstrated that combined therapy not only inhibited tumor growth (65%) compared to the untreated group but also relative to sodium selenite or GMZ used as monotherapy (up to 40%), increasing mice survival. These results were supported by the analysis of C57BL/6 albino mice bearing a Pan02-generated tumor, using the IVIS system. In conclusion, our results showed that sodium selenite is a potential agent for the improvement in the treatment of pancreatic cancer and should be considered for future human clinical trials.

Synthesis of cyclophosphamide metabolites by a peroxygenase from Marasmius rotula for toxicological studies on human cancer cells

Cyclophosphamide (CPA) represents a widely used anti-cancer prodrug that is converted by liver cytochrome P450 (CYP) enzymes into the primary metabolite 4-hydroxycyclophosphamide (4-OH-CPA), followed by non-enzymatic generation of the bioactive metabolites phosphoramide mustard and acrolein. The use of human drug metabolites as authentic standards to evaluate their toxicity is essential for drug development. However, the chemical synthesis of 4-OH-CPA is complex and leads to only low yields and undesired side products. In past years, fungal unspecific peroxygenases (UPOs) have raised to powerful biocatalysts. They can exert the identical selective oxyfunctionalization of organic compounds and drugs as known for CYP enzymes with hydrogen peroxide being used as sole cosubstrate. Herein, we report the efficient enzymatic hydroxylation of CPA using the unspecific peroxygenase from Marasmius rotula (MroUPO) in a simple reaction design. Depending on the conditions used the primary liver metabolite 4-OH-CPA, its tautomer aldophosphamide (APA) and the overoxidized product 4-ketocyclophosphamide (4-keto-CPA) could be obtained. Using a kinetically controlled approach 4-OH-CPA was isolated with a yield of 32% (purity > 97.6%). Two human cancer cell lines (HepG2 and MCF-7) were treated with purified 4-OH-CPA produced by MroUPO (4-OH-CPA^UPO). 4-OH-CPA^UPO–induced cytotoxicity as measured by a luminescent cell viability assay and its genotoxicity as measured by γH2AX foci formation was not significantly different to the commercially available standard. The high yield of 4-OH-CPA^UPO and its biological activity demonstrate that UPOs can be efficiently used to produce CYP-specific drug metabolites for pharmacological assessment.

Specific driving of the suicide E gene by the CEA promoter enhances the effects of paclitaxel in lung cancer

Classical chemotherapy for lung cancer needs new strategies to enhance its antitumor effect. The cytotoxicity, nonspecificity, and low bioavailability of paclitaxel (PTX) limits their use in this type of cancer. Suicide gene therapy using tumor-specific promoters may increase treatment effectiveness. We used carcinoembryonic antigen (CEA) as a tumor-specific promoter to drive the bacteriophage E gene (pCEA-E) towards lung cancer cells (A-549 human and LL2 mice cell lines) but not normal lung cells (L132 human embryonic lung cell line), in association with PTX as a combined treatment. The study was carried out using cell cultures, tumor spheroid models (MTS), subcutaneous induced tumors and lung cancer stem cells (CSCs). pCEA-E induced significant inhibition of A-549 and LL2 cell proliferation in comparison to L132 cells, which have lower CEA expression levels. Moreover, pCEA-E induced an important decrease in volume growth of A-549 and LL2 MTS producing intense apoptosis, in comparison to L132 MTS. In addition, pCEA-E enhanced the antitumor effects of PTX when combined, showing a synergistic effect. This effect was also observed in A-549 CSCs, which have been related to the recurrence of cancer. The in vivo study corroborated the effectiveness of the pCEA-E-PTX combined therapy, inducing a greater decrease in tumor volume compared to PTX and pCEA-E alone. Our results suggest that the CEA promoter is an excellent candidate for directing E gene expression specifically towards lung cancer cells, and may be used to enhance the effectiveness of PTX against this type of tumor.

Enhancement of Tumor Cell Death by Combining gef Gene Mediated Therapy and New 1,4-Benzoxazepin-2,6-Dichloropurine Derivatives in Breast Cancer Cells

New treatment modalities are urgently needed to better manage advanced breast cancer. Combination therapies are usually more effective than monotherapy. In this context, the use of cyclic and acyclic O,N-acetals derivative compounds in combination with the suicide gef gene shown a potent anti-tumor activity and represent a new generation of anticancer agents. Here, we evaluate the use of the gef gene to promote and increase the anti-tumor effect of cyclic and acyclic O,N-acetals purine derivatives and elucidate their mechanisms of action. Among all compounds tested, those with a nitro group and a cyclic pattern structures (FC-30b2, FC-29c, and bozepinib) are the most benefited from the gef gene effect. These compounds, in combination with gef gene, were able to abolish tumor cell proliferation with a minimal dose leading to more effective and less toxic chemotherapy. The effect of this combined therapy is triggered by apoptosis induction which can be found deregulated in the later stage of breast cancer. Moreover, the combined therapy leads to an increase of cell post-apoptotic secondary necrosis that is able to promote the immunogenicity of cancer cells leading to a successful treatment. This data suggests that this novel combination therapy represents a promising candidate for breast cancer treatment.

Tissue Specific Promoters in Colorectal Cancer

Colorectal carcinoma is the third most prevalent cancer in the world. In the most advanced stages, the use of chemotherapy induces a poor response and is usually accompanied by other tissue damage. Significant progress based on suicide gene therapy has demonstrated that it may potentiate the classical cytotoxic effects in colorectal cancer. The inconvenience still rests with the targeting and the specificity efficiency. The main target of gene therapy is to achieve an effective vehicle to hand over therapeutic genes safely into specific cells. One possibility is the use of tumor-specific promoters overexpressed in cancers. They could induce a specific expression of therapeutic genes in a given tumor, increasing their localized activity. Several promoters have been assayed into direct suicide genes to cancer cells. This review discusses the current status of specific tumor-promoters and their great potential in colorectal carcinoma treatment.

Specific Colon Cancer Cell Cytotoxicity Induced by Bacteriophage E Gene Expression under Transcriptional Control of Carcinoembryonic Antigen Promoter

Colorectal cancer is one of the most prevalent cancers in the world. Patients in advanced stages often develop metastases that require chemotherapy and usually show a poor response, have a low survival rate and develop considerable toxicity with adverse symptoms. Gene therapy may act as an adjuvant therapy in attempts to destroy the tumor without affecting normal host tissue. The bacteriophage E gene has demonstrated significant antitumor activity in several cancers, but without any tumor-specific activity. The use of tumor-specific promoters may help to direct the expression of therapeutic genes so they act against specific cancer cells. We used the carcinoembryonic antigen promoter (CEA) to direct E gene expression (pCEA-E) towards colon cancer cells. pCEA-E induced a high cell growth inhibition of human HTC-116 colon adenocarcinoma and mouse MC-38 colon cancer cells in comparison to normal human CCD18co colon cells, which have practically undetectable levels of CEA. In addition, in vivo analyses of mice bearing tumors induced using MC-38 cells showed a significant decrease in tumor volume after pCEA-E treatment and a low level of Ki-67 in relation to untreated tumors. These results suggest that the CEA promoter is an excellent candidate for directing E gene expression specifically toward colon cancer cells.

Enhanced antitumor activity of doxorubicin in breast cancer through the use of poly(butylcyanoacrylate) nanoparticles

The use of doxorubicin (DOX), one of the most effective antitumor molecules in the treatment of metastatic breast cancer, is limited by its low tumor selectivity and its severe side effects. Colloidal carriers based on biodegradable poly(butylcyanoacrylate) nanoparticles (PBCA NPs) may enhance DOX antitumor activity against breast cancer cells, thus allowing a reduction of the effective dose required for antitumor activity and consequently the level of associated toxicity. DOX loading onto PBCA NPs was investigated in this work via both drug entrapment and surface adsorption. Cytotoxicity assays with DOX-loaded NPs were performed in vitro using breast tumor cell lines (MCF-7 human and E0771 mouse cancer cells), and in vivo evaluating antitumor activity in immunocompetent C57BL/6 mice. The entrapment method yielded greater drug loading values and a controlled drug release profile. Neither in vitro nor in vivo cytotoxicity was observed for blank NPs. The 50% inhibitory concentration (IC50) of DOX-loaded PBCA NPs was significantly lower for MCF-7 and E0771 cancer cells (4 and 15 times, respectively) compared with free DOX. Furthermore, DOX-loaded PBCA NPs produced a tumor growth inhibition that was 40% greater than that observed with free DOX, thus reducing DOX toxicity during treatment. These results suggest that DOX-loaded PBCA NPs have great potential for improving the efficacy of DOX therapy against advanced breast cancers.

Gef gene therapy enhances the therapeutic efficacy of cytotoxics in colon cancer cells

The potential use of gene therapy to improve the response of patients with advanced cancer is being intensively analyzed. We evaluated the cytotoxic impact of the gef gene, a suicide gene, which has a demonstrated antiproliferative activity in tumor cells, in colon carcinoma cells in order to improve the antitumour effect of chemotherapeutic drugs used as first line treatment in the management of advanced colon cancer. We found that the gef gene induced a marked decrease in cell viability (50% in 24h) in T-84 cells through cell death by apoptosis. Interestingly, when gef gene expression was combined with drugs of choice in the clinical treatment of colon cancer (5-fluorouracil, oxaliplatin and irinotecan), a strong synergistic effect was observed with approximately a 15-20% enhancement of the antiproliferative effect. Our data demonstrate, for the first time, that gef gene expression induces significant growth arrest in colon cancer cells and that it is able to enhance the effect of some cytotoxic drugs compared with a single therapeutic approach. These results indicate the potential therapeutic value of the gef gene in colon cancer combination therapy.

Eukaryotic expression vectors bearing genes encoding cytotoxic proteins for cancer gene therapy

Cancer gene therapy is a promising direction for the treatment of cancer patients. A primary goal of all cancer therapies is to selectively target and kill tumour cells. Such therapies are administered via different approaches, including both viral and non-viral delivery; however, both methods have advantages and disadvantages. Transcriptional targeting enables genes encoding toxic proteins to be expressed directly in cancer cells. Numerous vectors have been created with the purpose of killing cancer cells, and some have successfully suppressed malignant tumours. Data concerning the function of vectors bearing genes that encode cytotoxic proteins under the control of different promoters, including tissue/tumour specific and constitutive promoters, is summarised here. This review focuses on vectors that bear genes encoding diphtheria toxin, Pseudomonas exotoxin A, caspases, gef, streptolysin, and melittin. Data describing the efficacy of such vectors have been summarised. Notably, there are vectors that killed cancer cell lines originating from the same type of cancer with differential efficiency. Thus, there is differential inhibition of cancer cell growth dependent on the cell line. In this review, the constructs employing genes whose expression induces cell death and the efficiency with which they suppress cancer cell growth will be summarised.

Catalase overexpression in mammary cancer cells leads to a less aggressive phenotype and an altered response to chemotherapy

Because reactive oxygen species (ROS) are naturally produced as a consequence of aerobic metabolism, cells have developed a sophisticated set of antioxidant molecules to prevent the toxic accumulation of these species. However, compared with normal cells, malignant cells often exhibit increased levels of intracellular ROS and altered levels of antioxidant molecules. The resulting endogenous oxidative stress favors tumor growth by promoting genetic instability, cell proliferation and angiogenesis. In this context, we assessed the influence of catalase overexpression on the sensitivity of breast cancer cells towards various anticancer treatments. Our data show that catalase overexpression in MCF-7 cells leads to a 7-fold increase in catalase activity but provokes a 40% decrease in the expression of both glutathione peroxidase and peroxiredoxin II. Interestingly, proliferation and migration capacities of MCF-7 cells were impaired by the overexpression of catalase, as compared to parental cells. Regarding their sensitivity to anticancer treatments, we observed that cells overexpressing catalase were more sensitive to paclitaxel, etoposide and arsenic trioxide. However, no effect was observed on the cytotoxic response to ionizing radiations, 5-fluorouracil, cisplatin or doxorubicin. Finally, we observed that catalase overexpression protects cancer cells against the pro-oxidant combination of ascorbate and menadione, suggesting that changes in the expression of antioxidant enzymes could be a mechanism of resistance of cancer cells towards redox-based chemotherapeutic drugs.

Synergistic antitumoral effect of combination E gene therapy and Doxorubicin in MCF-7 breast cancer cells

The low effectiveness of conventional therapies to achieve the long-term survival of metastatic breast cancer patients calls for the development of novel options. Genes encoding cytotoxic proteins have been proposed as a new strategy to enhance the antiproliferative activity of drugs. Combined therapy using these genes and classical antitumoral drugs are under intensive study. The E gene from ϕX174 encodes a membrane protein with a toxic domain that leads to a decrease in the tumour cell growth rate. With the aim of improving the anti-tumour effect on breast cancer cells of the currently used chemotherapeutic drugs (Paclitaxel, Docetaxel and Doxorubicin), we investigated the association of E suicide gene with these drugs. The effect of the combined therapy (gene therapy and cytotoxic) was determined by treating transfected MCF-7 cells and multicellular tumour spheroids (MTS) with drugs gradient concentrations. Our results showed that E gene has a direct oncolytic effect inducing a significant decrease in the proliferation rate of the MCF-7 cells. The E gene antitumoral activity was mediated by the induction of apoptosis (mitochondrial pathway). In addition, a significant enhancement of proliferation inhibition was observed when E gene transfection was associated with cytotoxic drugs in comparison to single treatments. The use of the combined therapy E gene-Doxorubicin obtained the greatest effect on the MCF-7 growth arrest. This therapeutic association also induced a significant enhancement of the MTS volume growth inhibition. Anti-tumour activity of the chemotherapeutic drugs classically used in the treatment of breast cancer was enhanced by E gene. Our in vitro results indicate that experimental therapeutic strategy based in the combined therapy E gene and cytotoxic drugs may be of potential therapeutic value as a new strategy for patients with advanced breast cancer.