Panoply™ Human MCAM Knockdown Stable Cell Line

Prostate cancer is the most common cancer in men and the second leading cause of cancer-related death. This study aimed to test the therapeutic applicability of a mAb targeting melanoma cell adhesion molecule (MCAM; CD146) for osteolytic prostate cancer bone metastases. The researchers evaluated the efficacy of MCAM targeting using an in vivo preclinical bone metastasis model and an in vitro bone microenvironment co-culture system. To demonstrate the impact of MCAM targeting and therapeutic applicability, an anti-MCAM mAb was used in vivo. MCAM is elevated in prostate cancer metastases resistant to androgen ablation. Treatment with DHT demonstrated upregulation of MCAM after castration. The researchers investigated MCAM function in a direct co-culture model of human prostate cancer cells and human osteoblasts and found that human osteoblasts exhibited reduced responses to MCAM knockdown in human prostate cancer cells. Furthermore, in an animal model of prostate cancer bone metastasis, inoculation of MCAM-deficient human prostate cancer cells into bone significantly reduced the formation of osteolytic lesions. RNA sequencing (RNA-seq) analysis supported this phenotype. Importantly, in vivo administration of anti-MCAM human monoclonal antibodies reduced tumor growth and osteolytic lesions. These results highlight the functional role of MCAM in the development of lytic bone metastasis and suggest that MCAM is a potential therapeutic target for prostate cancer bone metastasis.

To test the effect of MCAM knockdown on prostate cancer cell bone metastasis, researchers intraosseoinoculated male mice (sham-operated mice served as controls) with PC-3M-Pro4 MCAM knockdown cells and NT control cells expressing luciferase 2 (Luc2). Animals were monitored via bioluminescent imaging (BLI) throughout the experiment (Figure 1A). Animal body weight was monitored throughout the experiment, and bone lesion development was assessed by X-ray measurements (Figure 1B). MCAM knockdown significantly reduced the lytic phenotype of PC-3M-Pro4 cells compared to NT controls. This was confirmed by bone morphometric analysis (Figure 1C) and histological assessment (Figure 1D). Bone morphometric measurements revealed bone area in the knockdown groups similar to that of the sham-operated group, while bone area in mice injected with MCAM knockdown cells was significantly greater than that in mice injected with NT control cells (Figure 1E), despite BLI measurements showing similar tumor burden between the MCAM knockdown and NT control groups (Figure 1F). Finally, compared with NT controls, expression of the oncogene CRIPTO/TDGF1 was strongly suppressed in MCAM-knockdown cells, and molecules involved in bone remodeling (such as PTHLH and DKK1; Figure 1G) were generally regulated. Downregulation of CRIPTO/TDGF1 in MCAM-knockdown cells was also confirmed at the protein level (Figure 1H). Together, these data suggest that MCAM influences the expression of molecules that are important regulators of bone remodeling and bone metastasis.

Figure 1. MCAM knockdown reduces prostate cancer lytic bone metastasis in a preclinical mouse model. (Zoni E, et al., 2019)