A Portal Vein Injection Model to Study Liver Metastasis of Breast Cancer

Abstract

Breast cancer is the leading cause of cancer-related mortality in women worldwide. Liver metastasis is involved in upwards of 30% of cases with breast cancer metastasis, and results in poor outcomes with median survival rates of only 4.8 -15 months. Current rodent models of breast cancer metastasis, including primary tumor cell xenograft and spontaneous tumor models, rarely metastasize to the liver. Intracardiac and intrasplenic injection models do result in liver metastases, however these models can be confounded by concomitant secondary-site metastasis, or by compromised immunity due to removal of the spleen to avoid tumor growth at the injection site. To address the need for improved liver metastasis models, a murine portal vein injection method that delivers tumor cells firstly and directly to the liver was developed. This model delivers tumor cells to the liver without complications of concurrent metastases in other organs or removal of the spleen. The optimized portal vein protocol employs small injection volumes of 5 -10 μl, ≥ 32 gauge needles, and hemostatic gauze at the injection site to control for blood loss. The portal vein injection approach in Balb/c female mice using three syngeneic mammary tumor lines of varying metastatic potential was tested; high-metastatic 4T1 cells, moderate-metastatic D2A1 cells, and low-metastatic D2.OR cells. Concentrations of ≤ 10,000 cells/injection results in a latency of ~ 20 -40 days for development of liver metastases with the higher metastatic 4T1 and D2A1 lines, and > 55 days for the less aggressive D2.OR line. This model represents an important tool to study breast cancer metastasis to the liver, and may be applicable to other cancers that frequently metastasize to the liver including colorectal and pancreatic adenocarcinomas.

The Rodent Liver Undergoes Weaning-Induced Involution and Supports Breast Cancer Metastasis

“…This model permits outgrowth of liver lesions without concomitant metastasis in other organs (26). Further, to avoid cachexia, we utilized the less aggressive, isogenic, murine D2A1 mammary tumor cell line.…”

“…Mice were anesthetized, abdominal hair removed, and 5,000 D2A1 isogenic mammary tumor cells/10 µl PBS injected into the portal vein as described (26). Mice were euthanized at 5 weeks post-injection (Nullip, n=18; Inv2, n=17; R, n=8) and visible liver metastasis assessed at necropsy.…”

Fraser extracellular matrix complex subunit 1 promotes liver metastasis of gastric cancer

“…However, only allografts form liver metastasis using this technique, and tumor formation and proliferation in the spleen affects metastatic potential. In the present study, we administered portal vein injections, which proved suitable for evaluating liver metastasis . We used this model to show that engrafted FRAS1 ‐KO cells did not form detectable tumors, whereas tumors were rapidly generated by MKN1 cells.…”

“…In the present study, we administered portal vein injections, which proved suitable for evaluating liver metastasis. 50 We used this model to show that engrafted FRAS1-KO cells did not form detectable tumors, whereas tumors were rapidly generated by MKN1 cells. In contrast, the rate of suppression rate of tumor formation was 33% in the subcutaneous xenograft model.…”

HIF-1α promotes autophagic proteolysis of Dicer and enhances tumor metastasis

“…This model enables the spontaneous metastasis of the primary tumor through the portal system, thus mimicking the metastatic pattern in human colon cancer and generating liver and lung metastasis (47)(48)(49)(50). miR-200b was restored in CT-26/Luc cells stably expressing either WT or HLH-truncated HIF-1α for metastasis in animal experiments.…”