Fluorescence‐guided surgery of human prostate cancer experimental bone metastasis in nude mice using anti‐CEA DyLight 650 for tumor illumination

Abstract

The present report demonstrates efficacy of fluorescence-guided surgery (FGS) to resect and prevent recurrence of experimental skeletal metastasis in a nude-mouse model of human prostate cancer. Green fluorescent protein (GFP)-expressing PC-3 human prostate cancer cells were injected into the intramedullary cavity of the tibia in 25 nude mice. One week after implantation, monoclonal antibodies, specific for carcinoembryonic antigen (CEA), labeled with DyLight 650, were injected into the tail vein of 13 mice. Thirteen mice underwent FGS and 12 mice underwent bright-light surgery (BLS). Weekly GFP fluorescence imaging of the mice was performed to observe tumor recurrence. The extent of residual tumor after BLS was 13-fold greater than after FGS (p < 0.001). Time-course imaging visualized rapid growth of the residual tumor in the BLS group, whereas the FGS group showed only slight tumor growth and significantly improved disease-free survival of the treated mice. Our study demonstrated that FGS significantly reduced residual tumor as well as the recurrence of experimental prostate-cancer bone metastasis. The present results suggest that FGS will be effective for resection of skeletal metastases in selected patients with prostate cancer. Keywords: prostate cancer; bone metastasis; GFP; fluorescence-guided surgery; CEA Our laboratory has developed fluorescence-guided surgery (FGS) of cancer using clinically relevant mouse models of major types of cancer. [1][2][3][4][5][6][7][8][9][10][11] We have used green fluorescent protein, including delivery by tumorspecific adenovirus to label tumors for FGS, 2-4,10,11 as well as fluorophore-conjugated tumor-specific antibodies. 1,[5][6][7] We previously developed a model for fluorescenceguided surgery of tumors in the bone using human 143B osteosarcoma cells expressing red fluorescent protein (RFP), which were injected into the intramedullary cavity of the tibia in nude mice. The fluorescent areas of residual tumors after bright-light surgery (BLS) were approximately 100-fold greater than after FGS. BLS-treated mice had significant recurrence. In contrast, the FGS mice had very little recurring tumor growth. Disease-free survival (DFS) in the BLS-treated mice was 12.5% compared to 75.0% in the FGS-treated mice. 8 Bone metastasis in prostate cancer is a major problem for morbidity of this disease. We have previously developed mouse models of prostate cancer experimental and spontaneous bone metastasis. [12][13][14][15][16] In the present report, we demonstrate the strong efficacy of FGS on prostate-cancer experimental bone metastasis. MATERIALS AND METHODSCell Lines and Cell Culture Human PC-3 prostate cancer cells genetically engineered to express GFP using a retrovirus expression vector 12 were used in the current study. PC-3-GFP cells were cultured in DMEM supplemented with 1% penicillin/streptomycin (Invitrogen, Carlsbad, CA) and 10% fetal bovine serum (SigmaAldrich, St. Louis, MO) at 37˚C with 95% air and 5% CO 2 .

Non-invasively Imageable Tibia-tumor-fragment Implantation Experimental-bone-metastasis Mouse Model of GFP-expressing Prostate Cancer

“…In the present study, we established an experimental tibia-bone metastasis mouse model of prostate cancer. Compared to previous tibia-bone metastasis models (7)(8)(9)(10), in which cell injection was performed, this new procedure proved to be more accurate and efficient, since tumors grew in all the mice, a 100% establishment rate, compared to an approximately 90% in a previous study (8). The lower establishment rate by cell injection may be due to cells leaking out of the medullary cavity of the bone.…”

“…Evaluation of metastasis by detection of green fluorescent protein (GFP) fluorescence is a very powerful technique (7). Experimental tibia-metastasis mouse models of PC-3-GPF prostate cancer, with cell injection into the bone marrow, have been previously established (7)(8)(9)(10). However, the establishment ratio is inconsistent, depending on the technical level of the procedure and the quality of cells which are injected.…”

Therapeutic Efficacy of Cancer Stem Cell Vaccines in the Adjuvant Setting

“…There are many factors associated with tumor recurrence (4, 5). Several reports have described strategies to eliminate residual tumor cells after surgery (3, 6). However, effectively preventing local tumor recurrence remains a significant challenge.…”