Combined IFN-gamma-endostatin gene therapy and radiotherapy attenuates primary breast tumor growth and lung metastases via enhanced CTL and NK cell activation and attenuated tumor angiogenesis in a murine model.
BACKGROUND
Gene-radiotherapy, a combination of gene therapy and radiotherapy, is a new paradigm for cancer treatment, with the potential to simultaneously improve local and systemic breast cancer control. The aim of this study was to evaluate antitumor effect of interferon (IFN)-gamma-endostatin-based gene-radiotherapy in a murine metastatic breast tumor model, and to elucidate possible mechanisms involved.


METHODS
Murine mammary adenocarcinoma 4T1 cells transfected with pEgr-IFN-gamma and pEgr-endostatin plasmids were irradiated (2-20 Gy). IFN-gamma and endostatin levels in the culture supernatants were measured. In vivo female BALB/c mice were inoculated with 1 x 10(5) 4T1 cells by mammary fat pad injection and divided into control, empty vector, gene therapy (pEgr-IFN-gamma and pEgr-endostatin), radiotherapy, and combined gene-radiotherapy groups. Tumor growth, tumor/body weight ratio, lung metastases, and survival of the tumor-bearing mice were observed. Splenic cytotoxic T-lymphocyte (CTL) and natural killer (NK) cell activity and intratumor microvessel density were also assessed.


RESULTS
Irradiation significantly enhanced IFN-gamma and endostatin secretion from the transfected 4T1 cells. In vivo mice that received combined gene-radiotherapy showed maximal attenuation in tumor growth rate and lung metastases with increased survival compared with mice that received gene therapy or radiotherapy alone. This was associated with significantly enhanced CTL and NK cell activity and reduced intratumor microvessel density.


CONCLUSIONS
These results demonstrate that IFN-gamma-endostatin-based gene-radiotherapy provide a potent antitumor effect in a murine metastatic breast tumor model, which may relate to IFN-gamma-stimulated CTL and NK cell activation, and endostatin-induced antiangiogenic activity. Thus, gene-radiotherapy may represent a useful addition to neoadjuvant management of locally advanced breast cancer.
Liu
Lin Lin
LL
Department of Academic Surgery, University College Cork (UCC)/National University of Ireland (NUI), Cork University Hospital, Cork, Ireland.
Smith
Myles J
MJ
Sun
Bao Sheng
BS
Wang
Guan Jun
GJ
Redmond
H Paul
HP
Wang
Jiang Huai
JH
D000230:Adenocarcinoma / Q000235:genetics / Q000473:pathology / Q000556:secondary / Q000628:therapy*; D000818:Animals; D045744:Cell Line, Tumor; D003131:Combined Modality Therapy; D004195:Disease Models, Animal; D051766:Early Growth Response Protein 1 / Q000235:genetics; D043169:Endostatins / Q000008:administration & dosage; D005260:Female; D015316:Genetic Therapy; D007371:Interferon-gamma / Q000008:administration & dosage; D007694:Killer Cells, Natural / Q000187:drug effects / Q000276:immunology / Q000528:radiation effects; D008175:Lung Neoplasms / Q000235:genetics / Q000556:secondary / Q000628:therapy*; D015674:Mammary Neoplasms, Animal / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D051379:Mice; D008807:Mice, Inbred BALB C; D055806:Microvessels; D009389:Neovascularization, Pathologic / Q000628:therapy; D010957:Plasmids; D011878:Radiotherapy; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects / Q000276:immunology / Q000528:radiation effects
D051766:Early Growth Response Protein 1; C486109:Egr1 protein, mouse; D043169:Endostatins; D007371:Interferon-gamma