Panoply™ Human TNFSF13B Over-expressing Stable Cell Line

Although B-cell activating factor (BAFF, Tnfsf13b) is known to influence B-cell survival and proliferation, its specific role within the tumor microenvironment remains unclear. Here, researchers investigated how BAFF overexpression in breast cancer cells affects tumor growth and the functions of T and B cells within the tumor microenvironment. The results demonstrated that BAFF overexpression in 4T1 cells promoted in vivo tumor growth, suppressed CD8+ T-cell activity, and increased the population of intratumoral IL-10-producing CD5+ regulatory B cells. Through the interaction between BAFF and the BAFF receptor (BAFF-R), 4T1/BAFF cells directly enhanced the IL-10-producing capacity of CD5+ B cells, while the IL-10 derived from these CD5+ B cells inhibited IFN-γ secretion by T cells. Depletion of B cells partially reversed the pro-tumorigenic effects induced by BAFF overexpression. These findings reveal a novel mechanism by which BAFF promotes tumor progression: the induction of IL-10-producing regulatory B cells to suppress anti-tumor T-cell responses appears to be a critical step in BAFF's pro-tumorigenic activity.

Tumor growth was significantly accelerated in mice inoculated with BAFF-overexpressing 4T1 cells (4T1/BAFF). To determine whether this accelerated growth stemmed from the 4T1/BAFF cells themselves or the host immune system, the researchers first examined the growth characteristics of 4T1 cells following BAFF overexpression. The results showed that the in vitro growth rate of the BAFF-overexpressing tumor cells remained unchanged (Figure 1A). Furthermore, the researchers assessed apoptosis and found no significant induction of apoptosis associated with BAFF overexpression (Figure 1B). Tumor cells often suppress anti-tumor immune responses and facilitate immune escape by upregulating PD-L1 and downregulating CD86 and MHC class I molecules; therefore, the researchers examined changes in the expression of these surface molecules on the tumor cells. The results demonstrated that the expression levels of PD-L1 (Figure 1C), CD86 (Figure 1D), and MHC class I molecules (Figure 1E) did not change significantly in BAFF-overexpressing 4T1 cells. These findings indicate that BAFF overexpression in tumor cells affects neither cell growth nor the expression of molecules involved in cell-surface antigen presentation. Consequently, it is inferred that the accelerated tumor growth observed in mice inoculated with 4T1/BAFF cells is likely attributable to alterations in the host immune system.

Figure 1. Overexpression of BAFF in 4T1 tumor cells does not affect cell proliferation, apoptosis, or expression of antigen presentation-related molecules. (Lv Z, et al., 2025)