Human BTLA Stable Cell Line-CHO-K1

B and T lymphocyte attenuator (BTLA) is an immune checkpoint molecule that mediates tumor cell evasion of immune surveillance. Therefore, BTLA and its ligand herpes virus entry mediator (HVEM) are potential immunotherapy targets. Here, the study showed that BTLA is expressed in a variety of tumor cells. Loss of BTLA or HVEM promoted cell proliferation and colony formation, while overexpression of BTLA in BTLA knockout cells reversed this phenomenon. Conversely, overexpression of BTLA or HVEM inhibited tumor cell proliferation and colony formation. In addition, the proliferation rate of the high BTLA subpopulation was significantly slower than that of the low BTLA subpopulation. Mechanistically, the synergistic effect of BTLA and HVEM inhibited its major downstream extracellular regulated protein kinase (ERK1/2) signaling pathway, thereby preventing tumor cell growth. This study suggests that tumor cell-intrinsic BTLA/HVEM is a potential tumor suppressor and may have potential antagonists of immunotherapy, thus representing a potential biomarker for optimal cancer immunotherapy.

To functionally dissect the potential role of tumor-intrinsic BTLA in tumor cells, the researchers used two short hairpin RNAs (shRNAs) targeting different sequences in NCI-H1299 and A549 cells to knock down endogenous BTLA, and the results showed that cell proliferation and clone formation rates were significantly higher than those in the control group (Figure 1A-C). In addition, they used CRISPR-Cas9 technology to construct two BTLA knockout (KO) cell lines in NCI-H1299, which also led to increased cell proliferation. In contrast, overexpression of BTLA in both cell lines showed that cell proliferation and clone formation rates were inhibited (Figure 1D-1F), and increased mRNA and protein levels were observed.

Figure 1. Inhibition of tumor cell growth by tumor cell-intrinsic BTLA. (Cheng T Y, et al., 2022)