Murine Experimental Model of Original Tumor Development and Peritoneal Metastasis via Orthotopic Inoculation with Ovarian Carcinoma Cells

Summary

To clarify the multistep process of peritoneal dissemination of ovarian carcinoma, the current study presents a murine experimental model of original tumor development and peritoneal metastasis via orthotopic inoculation with these tumor cells.

Abstract

Epithelial ovarian carcinoma (EOC) is associated with a poor prognosis because it shows peritoneal dissemination. To improve the prognosis, it is important to control peritoneal dissemination. However, it is still unclear how tumor cells detach from primary lesions and attach to the mesothelium. The establishment of an appropriate animal model is needed to gain an understanding of the mechanism of peritoneal dissemination in vivo. In the current study, we introduce the process from the local injection of EOC cells into the murine ovarian surface to the development of metastasis, including the peritoneum and distant organs. Female nude mice (BALB/c nu/nu) at 8 weeks of age were used. Under a microscopic field of view, EOC cells (1 x 10⁵ cells/µl of medium-extracellular matrix (ECM)-based hydrogel/unilateral ovary/mouse) were injected into murine ovaries through a retroperitoneal approach from the dorsal flank. This proposed method is a less invasive procedure for the mouse and minimizes damage to the ovary. Here, we describe the methodological steps in the development of the original and metastatic tumor formation of EOC.

Introduction

Epithelial ovarian carcinoma (EOC) accounts for the highest rate of cancer-related mortality among gynecological malignancies¹. EOC is associated with a poor prognosis, primarily due to its late symptomatology, and is often associated with multiple intraperitoneal disseminations and distant metastases^2-4. Peritoneal dissemination is a multi-step process. Firstly, tumor cells detach from the primary lesions, and migrate into the abdominal cavity. When the tumor cells attach to the peritoneal mesothelium, they start to invade tissues through the mesothelium^5,6. In order to better understand the tumor biology (e.g., cancer progre....

Protocol

The treatment protocol follows the guidelines for animal experimentation adopted by Nagoya University.

1. Preparation of Cell Suspensions

1. Human ovarian clear cell carcinoma cell line.
   1. Maintain ES-2 cells¹² in RPMI-1640 medium with 10% fetal bovine serum (FBS) and penicillin/streptomycin (penicillin: 100 units/ml, streptomycin: 0.1 mg/ml). Culture cells at 37 °C in a 5% CO₂ humidified incubator.
   2. Collect cells in the logarithmic growth phase in 0.05% trypsin/0.02% EDTA solution (trypsin/EDTA).
      1. First, remove the old media from the cell culture vessel, then wash the cel....

Results

Six nude mice had their ovaries inoculated with the human clear cell carcinoma cell line ES-2, as described in this protocol. As shown in Figure 1A, after 2 weeks, 5 of the 6 mice had a tumor in the ovary inoculated with ES-2 cells, but there was no tumor in the contralateral ovary without inoculation (used as a control). Moreover, 2 of the 5 mice showed multiple peritoneal disseminations with ascites. Cells metastasize to the liver (Figure 1B). The ovari.......

Discussion

Animal models are essential to analyze the mechanisms of tumor development, progression, metastasis, and drug efficacy against cancer cells. Mice bearing human ovarian cancer cells also have been used as an animal model. Here, we describe a less invasive procedure for the administration of ovarian tumor cells at an orthotopic site. Using this procedure, inoculation into the ovary through a retroperitoneal approach from the dorsal flank offers significant advantages over other commonly used techniques. Firstly, orthotopic.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Matrigel matrix	BD	354234	ECM-based hydrogel
Insulin syringe	TERUMO	SS-05M2913	1/2 cc, 29 G x 1/2"
Suturing needle with suture			11 mm, 3/8, Nylon6-0
Reflex 7 mm Wound Clip Applier	CellPoint Scientific	204-1000
Reflex 7 mm wound clips	CellPoint Scientific	203-1000