Increased efficacy of doxorubicin delivered in multifunctional microparticles for mesothelioma therapy

Abstract

New and effective treatment strategies are desperately needed for malignant mesothelioma (MM), an aggressive cancer with a poor prognosis. We have shown previously that acid-prepared mesoporous microspheres (APMS) are nontoxic after intrapleural or intraperitoneal (IP) administration to rodents. The purpose here was to evaluate the utility of APMS in delivering chemotherapeutic drugs to human MM cells in vitro and in two mouse xenograft models of MM. Uptake and release of doxorubicin (DOX) alone or loaded in APMS (APMS-DOX) were evaluated in MM cells. MM cell death and gene expression linked to DNA damage/repair were also measured in vitro. In two severe combined immunodeficient mouse xenograft models, mice received saline, APMS, DOX or APMS-DOX injected directly into subcutaneous (SC) MM tumors or injected IP after development of human MMs peritoneally. Other mice received DOX intravenously (IV) via tail vein injections. In comparison to DOX alone, APMS-DOX enhanced intracellular uptake of DOX, MM death and expression of GADD34 and TP73. In the SC MM model, 33 weekly SC injections of APMS-DOX or DOX alone significantly inhibited tumor volumes, and systemic DOX administration was lethal. In mice developing IP MMs, significant (p < 0.05) inhibition of mesenteric tumor numbers, weight and volume was achieved using IP administration of APMS-DOX at one-third the DOX concentration required after IP injections of DOX alone. These results suggest APMS are efficacious for the localized delivery of lower effective DOX concentrations in MM and represent a novel means of treating intracavitary tumors.

Delivery of chemotherapeutic drugs in tumour cell-derived microparticles

“…The concentration of chemotherapeutic drug in MPs was measured by HPLC. Briefly, H22 tumour cell-derived, doxorubicin-packaging MPs were processed by lysis buffer, proteinase K, phenylmethylsulphonyl fluoride and DNase I according to previous description 54 . The HPLC system consisted of a 1525 Binary HPLC Pump, a 717 Plus Autosampler and a 2475 Multi-Wavelength Fluorescence Detector (Waters Corporation, Milford, CT).…”

Extracellular Signal-Regulated Kinase 5 and Cyclic AMP Response Element Binding Protein Are Novel Pathways Inhibited by Vandetanib (ZD6474) and Doxorubicin in Mesotheliomas

“…Images from viability studies were captured using an Olympus IX70 inverted light microscope (Olympus 24 hours, and total cell numbers were determined. Results (using both the colorimetric MTS Cell Proliferation Assay and counting of adherent, viable cells at 24 h) of dose-response studies using Dox at a range of concentration from 0.1 to 100 mM concentrations have been previously reported for the HMESO and H2373 (also referred to as PPM Mill) mesothelioma cell lines (11,37). Based on these results, concentrations of Dox (25 mM for HMESO and 100 mM for the more resistant H2373 line) were selected for studies here.…”

“…We selected Dox for our studies because this DNA intercalating agent is the most successful drug of choice to treat MMs in single-agent studies (33,34) and is used to treat MM and a number of other neoplasms in combination with other chemotherapeutic agents (35,36). In studies described here, we performed dose-response toxicity studies with Van and Dox alone and in combination on two well-characterized MM cell lines that are known to be sensitive (HMESO) or resistant (H2373) to Dox (37). We then examined, using Western blot analysis, levels of phosphorylated and total EGFR, ERK1, ERK2, ERK5, AKT, and CREB under these identical circumstances.…”

“…Cells were grown to 80 to 90% confluence and maintained in medium including 0.5% FBS for 24 hours before the addition of agents. Cell viability was studied using Van alone (5 mM), Dox alone (25 mM for HMESO and 100 mM for chemoresistant H2373 cells (37), and Van pretreatment 1 hour before Dox. Both cell lines were evaluated in doseresponse studies for Dox toxicity that were used here (37).…”

“…Cell viability was studied using Van alone (5 mM), Dox alone (25 mM for HMESO and 100 mM for chemoresistant H2373 cells (37), and Van pretreatment 1 hour before Dox. Both cell lines were evaluated in doseresponse studies for Dox toxicity that were used here (37). Twenty-five mM Dox is approximately equal to Dox concentrations in peritoneal fluids (average, 18.4 mM) after intracavitary Dox chemotherapy in patients with mesotheliomas (39).…”