Electrogene therapy using endostatin, with or without suicide gene therapy, suppresses murine mammary tumor growth and metastasis

Abstract

Syngeneic inoculated metastatic mammary cancers received direct intratumoral injection of a plasmid vector containing either endostatin (pEndo) with or without a suicide gene (pHSVtk), pHSVtk alone or control vector once a week for 8 weeks. We applied electrogene transfer to the tumors after each injection and administered ganciclovir (GCV) to pHSVtk-transfected mice using an osmotic minipump. Anticancer efficacy was monitored using a variety of parameters, namely tumor volume, intratumoral microvessel density and DNA synthesis, number of mice with metastasis, and number of sites of metastasis per mouse. Tumor volume was significantly lower in all therapeutic groups, with the most effective growth suppression in the pEndo þ pHSVtk/GCV group. Lymph node metastasis was significantly less frequent in all therapeutic groups, whereas the multiplicity of lung metastases was significantly lower only in the pEndo and pEndo þ pHSVtk/GCV groups. All therapeutic groups showed significantly lower intratumor microvessel density and DNA synthesis. The pEndo and pEndo þ pHSVtk/GCV groups also showed a significant reduction in the numbers of dilated lymphatic vessels containing intralumenal tumor cells. Our data suggest that endostatin electrogene therapy alone or in combination with pHSVtk/GCV suicide gene therapy is more beneficial than suicide gene therapy alone. The observed antimetastatic activity of endostatin may be of high clinical significance in the treatment of metastatic breast cancer.

Combination therapy with short interfering RNA vectors against VEGF-C and VEGF-A suppresses lymph node and lung metastasis in a mouse immunocompetent mammary cancer model

“…Electric pulses were delivered directly into the tumor via 'forceps' platinum plate electrodes (CUY650-10; Nepa Gene Co., Ltd, Ichikawa, Japan) using a CUY21EDIT square-wave electropulser (Nepa Gene Co., Ltd). Although the parameters for optimal gene electrotransfer (intratumoral injection of 50 mg plasmid, 8 pulses with a pulse length of 20 ms at 100 V) had been previously determined by us, 13,15,18,20 the electropulser device has since been replaced, and thus updated optimal conditions were determined using the pGL3 luciferase expression vector. Two mice each received 25, 50, 75, 100 and 125 V per treatment.…”

“…T03 for BJMC3879 cells. 18 Subsequently, the cells were plated in six-well plates. At 48 h post-transfection, the cells were collected and total RNA was extracted using an RNeasy Mini Kit (Qiagen, GmbH, Hilden, Germany).…”

“…Several studies have further reported the efficacy of using in vivo gene electrotransfer in animal cancer models. 13,18,[25][26][27][28] Tumor cell dissemination is mediated by a number of mechanisms, including direct invasion into local tissue, lymphatic spread and hematogenous spread. In general, the most common pathway of initial dissemination is through the lymphatics, with patterns of spread through afferent ducts.…”

Endostatin gene therapy enhances the efficacy of paclitaxel to suppress breast cancers and metastases in mice

“…Its antiangiogenic activity involves binding to integrin a5b1 [11] or E-selectin [12], inhibiting metalloproteinases [13], or influencing a set of growth-associated gene networks in endothelial cells [14,15]. Endostatin either suppresses or induces the regression of a wide variety of established tumors [16], including breast cancers and metastases in animal models [17][18][19][20]. Furthermore, endostatin stabilized tumor growth after chemotherapy in a NOD/SCID mouse model of human high-grade non-Hodgkin lymphoma [21].…”

Inhibition of Tumor Growth and Metastasis by a Combination of Anti-VEGF-C and Enhanced IL-12 Therapy in an Immunocompetent Mouse Mammary Cancer Model

“…Electric pulses were delivered directly to the tumor via "forceps" platinum plate electrodes (CUY650-10; Nepa Gene Co., Ltd., Ichikawa, Japan) using a CUY21EDIT square-wave electropulser (Nepa Gene Co., Ltd.). We had previously determined the parameters for optimal gene electrotransfer: for intratumoral injection of 50-75 g plasmid (dependent on tumor size as mentioned above), 8 pulses with a pulse length of 20 milliseconds at 100 volts proved to be most efficient [13,24,27]. Using calipers, we measured the size of each treated mammary tumor weekly and calculated tumor volumes using the formula maximum diameter x (minimum diameter) 2 x 0.4 [28].…”