Panoply™ Human CD47 Knockdown Stable Cell Line

CD47 plays a crucial role in the immune escape of tumor cells, but its role in regulating immune-independent biological processes such as proliferation and metastasis is still unclear. Here, researchers aimed to explore the immune-independent function of CD47 in colorectal cancer (CRC). These results showed that CD47 expression was upregulated in CRC patients and was associated with poor prognosis. Functional analysis showed that CD47 promoted the growth and metastasis of CRC cells both in vivo and in vitro. CD47 interacted with ENO1 and protected it from ubiquitin-mediated degradation, thereby promoting glycolytic activity and ERK phosphorylation in colorectal cancer cells. Inhibition of ENO1 reduced CD47-mediated cell growth and migration. Clinically, the combined expression of CD47 and ENO1 can provide a reliable predictive biomarker for the prognosis of colorectal cancer patients. These studies reveal an unconventional role for CD47, suggesting that targeting the CD47-ENO1 axis may provide a new therapeutic approach for colorectal cancer.

In control DLD1 and HCT8 cells, ENO1 protein levels were significantly reduced after treatment with the protein synthesis inhibitor cycloheximide (CHX), but CD47 overexpression partially rescued the CHX-induced decrease in ENO1 protein levels (Figure 1A-D). In contrast, accelerated ENO1 degradation was observed in CD47 knockdown HCT116 and SW480 cells. Protein degradation is mainly dependent on the proteasome system. Interestingly, the proteasome inhibitor MG132 blocked ENO1 turnover induced by CD47 knockdown in HCT116 and SW480 cells. In addition, regardless of the involvement of MG132, the endogenous ENO1 ubiquitination level in CD47 knockdown cells was increased compared with the control group (Figure 1E). In contrast, CD47 overexpression inhibited the turnover of ENO1 in HCT8 and DLD1 cells. These results suggest that CD47 may increase the stability of ENO1 by inhibiting proteasome-mediated degradation of ENO1 in colon cancer cells. The researchers then investigated whether CD47 regulates the ubiquitination level of ENO1. As expected, the ubiquitination level of ENO1 was significantly decreased in CD47-overexpressing HT29 colon cancer cells, whereas it was increased in CD47-knockdown HT29 cells (Figure 1F).

Figure 1. CD47 inhibits FBXW7-mediated ubiquitylation and degradation of ENO1. (Hu T, et al., 2020)