ABSTRACT
Gene therapy utilizing lipid-based delivery systems holds tremendous promise for the treatment of cancer. However, due to the potential adverse inflammatory and/or immune effects upon systemic administration, treatments thus far have been predominantly limited to intratumoral or regional treatment. Previous studies from our group have demonstrated the antitumor efficacy of systemically administered, folate-targeted, lipid-protamine-DNA complexes (LPD-PEG-Folate) against breast cancer using an immunodeficient xenogenic murine model. In the current study, the antitumor efficacy of LPD-PEG-Folate in a syngeneic, immune competent, murine model of breast cancer was examined. In this model, the potential inflammatory or immune responses and their effects on systemic delivery can be addressed. The 410.4 murine breast adenocarcinoma cell line was initially evaluated in vitro for its interactions with LPD-PEG-Folate and control LPD-PEG formulations. Utilizing fluorescently labeled formulations and fluorescence-activated cell sorting (FACS) analysis, a 1.6-fold enhancement of binding and internalization of LPD-PEG-Folate over LPD-PEG formulations was observed, suggestive of specific receptor interaction. Increased binding was manifested as 5-26-fold increases in luciferase gene expression in 410.4 cell transfection when comparing LPD-PEG-Folate to LPD-PEG. Moreover, in vivo treatment of 410.4 breast tumors in BALB/c mice with i.v. injected LPD-PEG-Folate delivering the HSV-1 thymidine kinase (TK) gene, in combination with gancyclovir treatment, resulted in a significant reduction in mean tumor volume (260.1 mm3) compared to the LPD-PEG-TK (914.1 mm3), as well as the vehicle (749.7 mm3) and untreated (825.3 mm3) control groups (day 25, P<.019). In addition to a reduced tumor volume, LPD-PEG-Folate-TK treatment also increased median survival from 25 days in the nontargeted LPD-PEG-TK groups to 31 days (P=.0011), which correlated with the termination of treatment. Together, these results demonstrate that in the context of a fully functional immune system, LPD-PEG-Folate-TK treatment possesses significant specific antitumor efficacy and the potential for further preclinical development.
Subject(s)
Adenocarcinoma/therapy , DNA/administration & dosage , Folic Acid/administration & dosage , Genetic Therapy/methods , Liposomes , Mammary Neoplasms, Experimental/therapy , Thymidine Kinase/genetics , Adenocarcinoma/immunology , Adenocarcinoma/pathology , Animals , Carrier Proteins/antagonists & inhibitors , Female , Folate Receptors, GPI-Anchored , Humans , Immunocompetence , Lipid Metabolism , Mammary Neoplasms, Experimental/immunology , Mammary Neoplasms, Experimental/pathology , Mice , Polyethylene Glycols , Protamines , Receptors, Cell Surface/antagonists & inhibitorsABSTRACT
The adenovirus type 5 E1A protein has been demonstrated to elicit antitumor effects through the induction of apoptosis, inhibition of cell cycle progression, induction of differentiated epithelial phenotypes, repression of oncogene expression and function, and sensitization to chemotherapeutic agents and radiation. These unique properties have led to use of the E1A gene in adenoviral and lipid-based gene therapy systems, and it has demonstrated antitumor effects in tumor xenograft model systems. However, the delivery systems used in those studies are best suited for local or intratumoral delivery rather than systemic delivery. Because the effective treatment of many primary tumors as well as metastatic disease requires systemic delivery systems, a novel gene delivery system composed of liposome/protamine/DNA (LPD) was investigated for systemic delivery of the E1A gene. Athymic nude mice bearing human breast (MDA-MB-361) or head and neck (WSUHN-31) tumor xenografts were treated i.v. with LPD-E1A, and the expression of E1A protein and effects on tumor growth were assessed. In the MDA-MB-361 breast model, expression of E1A protein was detected in the tumors after LPD-E1A treatment, which was associated with down-regulation of HER-2/neu protein expression and the presence of apoptotic cells. Tumor volume was also smaller in mice treated with LPD-E1A than in controls in both of the xenograft models. Lastly, LPD-E1A in combination with paclitaxel was more effective than LPD-E1A or paclitaxel alone in the MDA-MB-361 model. Additional preclinical and clinical development of LPD-E1A is warranted for the treatment of advanced or metastatic cancer.
