Panoply™ Human BDNF Knockdown Stable Cell Line

Inhibitors of DNA binding and cell differentiation (ID) proteins regulate cellular differentiation and tumor progression. It remains unclear whether ID family proteins link pathological differentiation with cancer stemness in colorectal cancer. This study found that among LGR5-high colon cancer stem cells, only ID4-and not other ID family proteins-was highly expressed. High ID4 expression correlates with poor pathological differentiation of colorectal tumors and shorter patient survival. Knockdown of ID4 inhibits the growth and proliferation of colon cancer cells and enhances their chemosensitivity. Gene expression profiling identified brain-derived neurotrophic factor (BDNF) as a downstream target of ID4 in colorectal cancer. BDNF knockdown inhibits colon cancer cell growth and migration, whereas BDNF expression promotes proliferation, resistance to anoikis, and chemoresistance. Silencing ID4 attenuates epithelial-mesenchymal transition (EMT) characteristics in colon cancer cells. Gene clustering analysis revealed that ID4 and BDNF expression clustered with mesenchymal markers rather than epithelial genes; silencing BDNF reduced the expression of mesenchymal markers such as Vimentin, CDH2, and SNAI1. These results indicate that the ID4-BDNF signaling pathway regulates the survival of colorectal cancer cells and holds promise as a prognostic marker for the disease.

Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis confirmed that BDNF expression was significantly reduced in ID4-silenced cells (Figure 1A). Dot plot analysis revealed that colorectal cancer tissues with high ID4 expression tended to exhibit higher BDNF levels compared to those with low ID4 expression (Figure 1B). Correlation analysis indicated a positive correlation between BDNF and ID4 expression in colorectal cancer (Figure 1C). To further investigate the role of BDNF in ID4-mediated colon cancer progression, researchers knocked down BDNF in DLD1 cells and confirmed the reduction in BDNF expression via qRT-PCR and enzyme-linked immunosorbent assay (ELISA) (Figure 1D). Colony formation assays demonstrated that the colony-forming ability of BDNF-knockdown colon cancer cells was reduced (Figure 1E). Cell tracking analysis showed that the migration of BDNF-knockdown colon cancer cells was inhibited (Figure 1F). These results indicate that BDNF expression is involved in the ID4-regulated growth and migration of colon cancer cells.

Figure 1. ID4 induces BDNF, regulating oncogenesis of colon cancer cells. (Ha C T, et al., 2021)