Chemoinducible gene therapy: A strategy to enhance doxorubicin antitumor activity

Synergistic therapeutic strategies and engineered nanoparticles for anti-vascular endothelial growth factor therapy in cancer

Angiogenesis is one of the defining characteristics of cancer. Vascular endothelial growth factor (VEGF) is crucial for the development of angiogenesis. A growing interest in cancer therapy is being caused by the widespread use of antiangiogenic drugs in treating several types of human cancer. However, this therapeutic approach can worsen resistance, invasion, and overall survival. As we proceed, refining combination strategies and addressing the constraint of targeted treatments are paramount. Therefore, major challenges in using novel combinations of antiangiogenic agents with cytotoxic treatments are currently focused on illustrating the potential of synergistic therapeutic strategies, alongside advancements in nanomedicine and gene therapy, present opportunities for more precise interference with angiogenesis pathways and tumor environments. Nanoparticles have the potential to regulate several crucial activities and improve several drug limitations such as lack of selectivity, non-targeted cytotoxicity, insufficient drug delivery at tumor sites, and multi-drug resistance based on their unique features. The goal of this updated review is to illustrate the enormous potential of novel synergistic therapeutic strategies and the targeted nanoparticles as an alternate strategy for t treating a variety of tumors employing antiangiogenic therapy.

Docetaxel increases antitumor efficacy of oncolytic prostate-restricted replicative adenovirus by enhancing cell killing and virus distribution

BACKGROUND

We explored multiple molecular mechanisms of the combination of docetaxel and an oncolytic prostate-restricted replication competent adenovirus (Ad) (PRRA) in advanced prostate cancer (PCa) models. The combinational therapy has potential to overcome the therapeutic limitations of poor virus distribution inside solid tumors.

METHODS

We evaluated the effect of docetaxel on the antitumor efficacy and efficiency of virus transduction, transgene expression and virus distribution of PRRA in a prostate-specific antigen/prostate-specific membrane antigen-positive tumor xenograft model. We also evaluated the effect of docetaxel on apoptosis induction, cell killing and the efficiency of transgene expression and virus replication in vitro.

RESULTS

Tumor growth inhibition was significantly enhanced when docetaxel was administrated before intratumor injection of PRRA. In vivo dual-photon microscopy and ex vivo fluorescence microscopy and immunohistochemistry showed that docetaxel increased transgene expression and expanded virus distribution. The combination of docetaxel and PRRA also increased cell apoptosis. In vitro, docetaxel significantly increased cell killing in PRRA-treated PCa cells. Docetaxel significantly increased Ad-mediated trangene expression independent of Ad binding receptors and replication capability. Docetaxel increased the activity of cytomegalovirus (CMV) promoter but not of a chimeric prostate-specific enhancer, resulting in higher transgene expression. The enhanced CMV promoter activity resulted from activation of p38 mitogen-activated protein kinase (MAPK) because inhibition of p38 MAPK blocked the docetaxel-induced increase in CMV promoter activity.

CONCLUSIONS

Combining docetaxel with an oncolytic PRRA improved therapeutic potential by expanding virus distribution and enhancing cell apoptosis and killing. These studies suggested a novel mechanism for enhancing the effect of therapeutic genes delivered by a PRRA.

Doxorubicin Directs the Accumulation of Interleukin-12–Induced IFNγ into Tumors for Enhancing STAT1–Dependent Antitumor Effect

PURPOSE

To examine the mechanism by which doxorubicin plus interleukin-12 (IL-12) gene transfer induces enhanced therapeutic efficacy against tumors.

EXPERIMENTAL DESIGN

Tumor-bearing mice were treated with doxorubicin, IL-12-encoding plasmid DNA, doxorubicin plus IL-12-encoding plasmid DNA, or plasmid DNA control. Doxorubicin was systemically given via i.p. injection, and IL-12 was systemically expressed via i.m. injection. To show that doxorubicin enhances the accumulation of IL-12-induced IFN gamma into tumors and the signal transducer and activator of transcription 1 (Stat1)-dependent antitumor efficacy, the distribution of IFN gamma and the therapeutic end points, such as T-cell infiltration, inhibition of tumor vessel density, tumor growth inhibition, and inhibition of spontaneous tumor metastasis in wild-type and Stat1(-/-) host and tumors were determined after the treatment at the indicated time points.

RESULTS

In this study, a novel mechanism was unveiled. We discovered that doxorubicin enhances the accumulation of IL-12-induced IFN gamma in tumors. The doxorubicin-mediated accumulation of IFN gamma in tumors is caused by an increased accumulation of IFN gamma-secreting immune cells and not by a direct translocation of IFN gamma protein into tumors. Depletion of immune cells reverses the doxorubicin-mediated accumulation of IFN gamma into tumors and reverses the inhibition of tumor vessel density induced by coadministration of doxorubicin and IL-12 DNA. Knocking out IFN gamma signaling in the tumor host reverses the significant inhibition of tumor growth by coadministration of doxorubicin and IL-12.

CONCLUSIONS

The enhanced antitumor efficacy by coadministration of doxorubicin and IL-12 is dependent on the accumulation of IFN gamma in tumors. This discovery provides a possible strategy to reduce side effects caused by IL-12.