The impact of the ovarian microenvironment on the anti-tumor effect of SPARC on ovarian cancer

Orthotopic, syngeneic mouse model to study the effects of epithelial-stromal interaction

One of the difficulties in studying ovarian cancer historically has been the lack of a suitable animal model that replicates the human disease. Mouse models that utilize intraperitoneal implantation of tumorigenic cells lack interaction between the transformed ovarian epithelial cells and the ovarian stroma, which we have shown to be an integral component in replicating the etiology seen in human epithelial ovarian cancer (Greenaway, Gynecol Oncol 108:385-394, 2008). Xenograft models generally require the use of immunocompromised hosts, which then eliminates the influence of the immune system in disease progression, which also has been shown to be an important part of the progression of epithelial ovarian cancer (EOC). In this chapter, we describe the generation and optimization of an orthotopic, syngeneic mouse model and illustrate the importance of facilitating epithelial-stromal cell interaction to more closely replicate human EOC.

SPARC is a key regulator of proliferation, apoptosis and invasion in human ovarian cancer

Background

Secreted protein acidic and rich in cysteine (SPARC), a calcium-binding matricellular glycoprotein, is implicated in the progression of many cancers. In this study, we investigated the expression and function of SPARC in ovarian cancer.

Methods

cDNA microarray analysis was performed to compare gene expression profiles of the highly invasive and the low invasive subclones derived from the SKOV3 human ovarian cancer cell line. Immunohistochemistry (IHC) staining was performed to investigate SPARC expression in a total of 140 ovarian tissue specimens. In functional assays, effects of SPARC knockdown on the biological behavior of ovarian cancer cells were investigated. The mechanisms of SPARC in ovarian cancer proliferation, apoptosis and invasion were also researched.

Results

SPARC was overexpressed in the highly invasive subclone compared with the low invasive subclone. High SPARC expression was associated with high stage, low differentiation, lymph node metastasis and poor prognosis of ovarian cancer. Knockdown of SPARC expression significantly suppressed ovarian cancer cell proliferation, induced cell apoptosis and inhibited cell invasion and metastasis.

Conclusion

SPARC is overexpressed in highly invasive subclone and ovarian cancer tissues and plays an important role in ovarian cancer growth, apoptosis and metastasis.