Pharmacokinetics of combined gene therapy expressing constitutive human GM-CSF and hyperthermia-regulated human IL-12.

BACKGROUND: An adenovirus that expresses both interleukin (IL)-12 and granulocyte-macrophage colony-stimulating-factor (GM-CSF) has been proven to be very effective in treating several tumors, but causes serious normal tissue toxicities. METHODS: In this study, a novel adenoviral vector was constructed by placing the human GM-CSF gene under the control of the CMV-IE promoter and human IL-12 gene under the control of heat shock protein 70B gene promoter. Both hGM-CSF and hIL-12 expressions in virus-infected tumor cells were analyzed in vitro and in vivo when underlying single or multiple rounds of hyperthermia. RESULTS: We observed constitutive high expression of human GM-CSF and heat-induced expression of human IL-12 after a single round of hyperthermia post viral infection. The heat-induced hIL-12 expression exhibited a pulse-like pattern with a peak at 24 hrs followed by a decline 48 hrs post heat stress. Repeated heat treatment was more effective in inducing hIL-12 expression than a one-time heat treatment. Interestedly, we also observed that constitutive expression of hGM-CSF could be stimulated by heat stress in tested tumor cells. CONCLUSION: Our study provided a novel strategy for combined gene therapy that allows constitutive expression of a non-toxic gene such as GM-CSF and heat-induced expression of a toxic gene such as IL-12. In addition, our study also showed that hyperthermia can be used to trigger gene expression in temporal and special manner.

Antitumor-promoting activity of lignans: inhibition of human cytomegalovirus IE gene expression.

BACKGROUND: Chemoprevention is a promising new approach to cancer prevention. Since the beginning of chemoprevention studies, short-term in vitro models used in the study of carcinogenesis have been applied in the identification of antitumor-promoting agents. MATERIALS AND METHODS: The lignans threo-4,4'-dihydroxy-3-methoxylignan, (-)-dihydroguaiaretic acid, 4'-hydroxy-3,3',4-trimethoxylignan, 3,3',4,4'-tetramethoxylignan, 4,4'-diacetyl-3,3'-dimethoxylignan, talaumidin, heliobuphthalmin, (-)-dihydro-cubebin, and hinokinin were evaluated for their ability to inhibit human cytomegalovirus (HCMV) IE-antigen expression in lung cancer cells (A549). RESULTS: Most of the evaluated compounds reduced IE-antigen expression of HCMV, the best result being obtained with 4,4'-dihydroxy-3-methoxylignan. However, a dose-dependent significant increase of IE-antigen expression was found for the derivative (-)-dihydrocubebin. CONCLUSION: The results of this study suggest that some of these lignans might be valuable as potential cancer chemopreventive agents.

Preclinical evaluation of synergistic effect of telomerase-specific oncolytic virotherapy and gemcitabine for human lung cancer.

A phase I dose-escalation study of telomerase-specific oncolytic adenovirus, OBP-301 (Telomelysin), is now under way in the United States to assess feasibility and to characterize its pharmacokinetics in patients with advanced solid tumors. The present preclinical study investigates whether OBP-301 and a chemotherapeutic agent that is commonly used for lung cancer treatment, gemcitabine, are able to enhance antitumor effects in vitro and in vivo. The antitumor effects of OBP-301 infection and gemcitabine were evaluated by 2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide inner salt assay. In vivo antitumor effects of intratumoral injection of OBP-301 in combination with systemic administration of gemcitabine were assessed on nu/nu mice s.c. xenografted with human lung tumors. OBP-301 infection combined with gemcitabine resulted in very potent synergistic cytotoxicity in human lung cancer cells. The three human lung cancer cell lines treated with OBP-301 for 24 hours tended to accumulate in S phase compared with controls. The proportion of cells in S phase increased from 43.85% to 56.41% in H460 cells, from 46.72% to 67.09% in H322 cells, and from 38.22% to 57.67% in H358 cells. Intratumoral injection of OBP-301 combined with systemic administration of gemcitabine showed therapeutic synergism in human lung tumor xenografts. Our data suggest that the combination of OBP-301 and gemcitabine enhances the antitumor effects against human lung cancer. We also found that the synergistic mechanism may be due to OBP-301-mediated cell cycle accumulation in S phase. These results have important implications for the treatment of human lung cancer.

A large animal model to evaluate the effects of Hsp90 inhibitors for the treatment of lung adenocarcinoma.

Ovine pulmonary adenocarcinoma (OPA) is a naturally occurring lung cancer of sheep caused by Jaagsiekte sheep retrovirus (JSRV). The JSRV envelope glycoprotein (Env) functions as a dominant oncoprotein in vitro and in vivo. In order to develop the basis for the use of OPA as a lung cancer model, we screened a variety of signal transduction inhibitors for their ability to block transformation by the JSRV Env. Most inhibitors were not effective in blocking JSRV Env-induced transformation. On the contrary, various Hsp90 inhibitors efficiently blocked JSRV transformation. This phenomenon was at least partly due to Akt degradation, which is activated in JSRV-transformed cells. Hsp90 was found expressed in tumor cells of sheep with naturally occurring OPA. In addition, Hsp90 inhibitors specifically inhibited proliferation of immortalized and moreover primary cells derived from OPA tumors. Thus, OPA could be used as a large animal model for comprehensive studies investigating the effects of Hsp90 inhibitors in lung adenocarcinoma.

Macrocyclic lathyrane diterpenes as antitumor promoters.

Human cytomegalovirus (CMV) preferentially infects tumor tissues and the accumulated CMV immediate-early (IE) antigen may lead to tumor promotion and progression. The development of strategies to inhibit human CMV IE antigen expression and/or function is an important goal to prevent and treat certain forms of cancers associated with human CMV. The aim of this study was to search for antitumor promoters from plant sources. The effect of six macrocyclic lathyrane-type diterpenoids, latilagascenes A-E (1-5) and jolkinol B (6), isolated from the methanol extract of Euphorbia lagascae, on the expression of IE antigen in lung cancer cells (A549) infected by CMV was studied. All the compounds, except latilagascene D (4), decreased IE antigen expression of CMV.