Knockdown of BAP31 Downregulates Galectin-3 to Inhibit the Wnt/β-Catenin Signaling Pathway to Modulate 5-FU Chemosensitivity and Cancer Stemness in Colorectal Cancer

Abstract

Increased stemness is causally linked to the development of chemoresistance in cancers. B-cell receptor-associated protein 31 (BAP31) has been identified to play an oncogenic role in many types of cancer. However, the role of BAP31 in 5-fluorouracil (5-FU) chemosensitivity and stemness of colorectal cancer (CRC) is still unknown. The aim of this study was to investigate the biological function and molecular mechanism of BAP31 in regulating 5-FU chemosensitivity and stemness. The correlation between BAP31 expression and 5-FU chemosensitivity was examined using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide and colony formation assays. Cancer stemness was analyzed using tumor sphere formation and Western blot assays. Western blot and immunofluorescence analyses of the knockdown cell lines were performed to explore the possible mechanisms. Finally, we investigated the function of BAP31 by constructing xenograft nude mouse models in vivo. In this study, we demonstrated that BAP31 was increased in CRC cells, and knockdown of BAP31 reduced the half maximal inhibitory concentration (IC50) of 5-FU, while this effect was reversed by overexpression of BAP31. In addition, knockdown of BAP31 substantially reduced the stemness of CRC cells in vitro. Consistently, knockdown of BAP31 significantly suppressed the tumorigenicity and stemness of CRC in vivo. The functional study further suggested that knockdown of BAP31 downregulated galectin-3 to inhibit the accumulation of β-catenin, which in turn repressed the transcription of downstream target genes (c-MYC, SOX2) of the Wnt/β-catenin signaling pathway. Knockdown of BAP31 reduced stemness by inhibiting the Wnt/β-catenin signaling pathway to increase 5-FU chemosensitivity. Importantly, intrabodies against BAP31 suppressed tumor growth and enhanced the antitumor effects of 5-FU in vivo. Therefore, using intrabodies against BAP31 may be a strategy for improving the antitumor effect of 5-FU in CRC.

TLR2 and TLR9 Blockade Using Specific Intrabodies Inhibits Inflammation-Mediated Pancreatic Cancer Cell Growth

“…Moreover, antibodies that clearly work in advanced colon cancer through a signaling blockade during angiogenesis did not show relevant benefits in patients with pancreatic cancer. To overcome the limitation of desirable intracellular signaling blockades in tumor cells, intrabodies have been designed that are capable of targeting intracellular tumor-associated antigens and neoantigens in cells and xenograft mouse models [27,29,[51][52][53][54][55][56][57][58][59][60]. This strongly supports the further development of relevant intrabodies, with the goal of setting up clinical trials.…”

BAP31 Promotes Angiogenesis via Galectin-3 Upregulation in Neuroblastoma

“…HIF-1α positively correlated with BAP31 overexpression, and the knockdown of BAP31 reduced the expression of HIF-1α despite protein stabilization with MG132 ( Figure 3 ). In a recent study, BAP31 knockdown positively correlated with GAL-3 in colorectal cancer and affected cancer cell stemness [ 22 ]. These findings underscore the role of BAP31 in mediating the expression of GAL-3 and VEGFA in neuroblastoma.…”

“…BAP31 is linked to cancer cell proliferation, metastasis, and shortened survival [ 19 , 20 , 21 ]. Recently, BAP31 was reported to promote angiogenesis in colorectal cancer [ 22 ]. Due to its widespread expression, BAP31 has emerged as a promising candidate for potential cancer therapy strategies aimed at inducing apoptosis and advancing vaccine development.…”

Galectin-3 and Autophagy in Renal Acute Tubular Necrosis

“…This kind of bidirectional relationship often implies a feedback loop, where the activation of one component influences the activity of the other, creating a dynamic regulatory network. The identification of Gal-3 as a novel binding partner of β-catenin adds another layer to the complexity of the interactions between Gal-3 and signaling pathways related to cell proliferation and survival [42]. The involvement of Gal-3 in various cellular processes, including its associations with NF-κB and β-catenin, suggests a multifaceted role for Gal-3 in modulating cell functions and responses to stress or inflammation.…”