GFP/Luc Reporter Cell Line - RM-1

Cancer-induced bone pain (CIBP) is the most common and debilitating symptom of bone-metastatic cancer, severely impairing patients' quality of life. To better understand the factors and mechanisms underlying CIBP, it is crucial to establish animal models that are clinically relevant and accurately recapitulate the pain symptoms and disease progression observed in patients with bone-metastatic cancer. Here, researchers provide a detailed characterization of a syngeneic mouse model of prostate cancer-induced bone pain. They transfected a prostate cancer cell line (RM1) with green fluorescent protein (GFP) and luciferase reporter genes to enable longitudinal visualization of tumor growth in vivo and to assess the interplay between sensory neurons and tumor cells within the bone microenvironment. Following the intra-femoral injection of RM1 prostate cancer cells into male C57BL/6 mice, the researchers observed that between days 12 and 21 post-inoculation, tumor-bearing mice exhibited a progressive increase in spontaneous protective behaviors-specifically, painful limb avoidance-in the inoculated limb compared to sham-operated controls. During this same period (days 12 to 21 post-inoculation), tumor-bearing mice demonstrated a progressive decline in both total running distance and the percentage of time spent maintaining optimal speed, relative to the sham group. Furthermore, osteolytic lesions and aberrant periosteal bone formation were observed in the tumor-bearing femurs, findings that closely mirror the clinical imaging manifestations seen in patients with bone-metastatic prostate cancer. The tumor-bearing mice exhibited significant pathological alterations: expression of the injury marker ATF3 was markedly upregulated within the ipsilateral dorsal root ganglia (DRG), accompanied by an upward trend in the expression of the neuropeptides SP and CGRP; concurrently, levels of central sensitization and glial cell activation were significantly elevated within the ipsilateral spinal cord. This fully immunocompetent mouse model, particularly when utilized in conjunction with cell-type-specific transgenic mouse lines, promises to serve as an invaluable research tool.

Here, researchers injected RM1 prostate cancer cells co-expressing luciferase and GFP (RM1-GFP) into the femoral medullary cavities of male C57BL/6 mice (Figure 1A). Within three weeks post-inoculation, they observed progressive tumor growth, manifested as a gradual increase in bioluminescence imaging (BLI) signals associated with the ipsilateral hind limb. On days 7, 14, and 20 post-inoculation, the BLI signal intensity in the tumor-bearing group (but not in the sham-operated group) was significantly higher than that observed on day 1 post-inoculation (Figure 1B, C). During this period, no BLI signals exceeding background levels were detected in the contralateral hind limbs or other parts of the bodies of the tumor-bearing mice.

Figure 1. Disease progression in orthotopic model of prostate cancer (PCa) induced bone pain. (Jimenez-Andrade J M, et al., 2023)