A fluorescent orthotopic model of metastatic cervical carcinoma

Abstract

Currently, there is no mouse model of cervical cancer that allows for the study of the later stages of the disease, including metastasis. We report here the development of an orthotopic model of human cervical carcinoma in which tumor fragments are surgically implanted into the cervix of SCID mice. The human cervical carcinoma cell lines used in this study (CaSki, ME-180, and SiHa) have been engineered to stably express the fluorescent proteins enhanced green fluorescent protein (EGFP) or DsRed2, allowing for in vivo optical monitoring of tumor growth and metastasis. The cervical implants develop into large intraperitoneal masses involving the entire reproductive tract, with little local invasion of other abdominal structures. These tumors metastasize initially to local lymph nodes and later to lung, a pattern consistent with the clinical course of the disease. It was found that the use of the DsRed2 protein as a fluorescent marker has distinct advantages over EGFP due to the wavelength of its emission spectrum (575–625 nm vs 500–550 nm). Tissue penetration of light at this wavelength is greater, and the auto-fluorescence of mouse tissues is less intense, resulting in an enhanced signal to noise ratio compared to results obtained with EGFP. This model should allow for a more relevant investigation of the factors that affect the metastasis of cervical carcinoma and presents an opportunity to evaluate potential therapeutic strategies designed to prevent the spread of disease.

Abbreviations: SCID – severe combined immunodeficient; EGFP – enhanced green fluorescent protein; VEGF – vascular endothelial growth factor; PD-ECGF – platelet-derived endothelial cell growth factor; MMP – matrix metalloproteinase; HPV – human papilloma virus; ATCC – American type culture collection; α-MEM – alpha minimal essential medium; FBS – fetal bovine serum; CMV – cytomegalovirus; FACS – fluorescence activated cell sorting