Investigation of The Effects of The Toll-Like Receptor 4 Pathway on Immune Checkpoint Vista in Pancreatic Cancer

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is one of the most common malignant tumors of the pancreas. Preclinical studies show that it evades the immune system with immune checkpoints and promotes tumor development. V-domain Ig suppressor of T cell activation (VISTA) is a new immune-check point from the B7 family and is highly expressed in cancer cells. Overexpression of toll like receptor 4 (TLR4) in pancreatic adenocarcinoma is associated with inducing tumorigenesis, tumor growth and resistance to chemotherapy. Naloxone is an opioid and inhibits TLR4-ligand association. In this study, we investigated the connection of TLR4 and downstream pathway with immune-check point VISTA in pancreatic cancer proliferation. We first collected pancreatic cancer-related datasets using the GEPIA2 and UALCAN databases. Based on the data obtained the effect of different concentrations and incubation times of Naloxone were used on PANC-1 cells proliferation. Combination of Naloxone and VISTA-siRNA were applied, and effect of both Naloxone and combined reatment on TLR4, Interleukin 1 receptor associated kinase 4 (IRAK4) and VISTA gene expression were analysed in pancreatic cancer cells. As a result of analysis with Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR), gene expression levels of TLR4, IRAK4 and VISTA were significantly suppressed and cell proliferation was significantly reduced. We found that administration of Naloxone and VISTA-siRNA in combination to PDAC cells suppressed signaling. Therefore, we considered that the relationship between VISTA and TLR4 signaling pathways and the other possible associated signal molecules may be an important marker in determining the response of immune checkpoint inhibitors in cancer treatment.

IGSF11 and VISTA: a pair of promising immune checkpoints in tumor immunotherapy

“…The melanoma animal model shows that the block of VISTA promotes the proliferation, infiltration and effector role of T cells, reducing the count and inhibiting the activation of MDSCs and Tregs, finally, boosting the growth of the melanoma [34]. In PDAC (pancreatic ductal adenocarcinoma), the expression of VISTA may be associated with TLR4; the downregulation of VISTA and TLR4 by siRNA and naloxone, respectively, can inhibit the growth of PDAC, indicating that VISTA and TLR4, with their downstream signal pathways, are all involved in PDAC growth [83]. Given that VISTA is also accumulated in cytoplasm of tumor cells, we consider that VISTA may bind with IGSF11 in cytoplasm and exert in tumor proliferation, but this hypothesis warrants more confirmation (Fig.…”

Quercetin improves pancreatic cancer chemo‐sensitivity by regulating oxidative‐inflammatory networks

“…Upregulation of TLR4 in the tumor microenvironment will activate the signal transducer and activator of transcription 3 (STAT3) pathway that reduces the sensitivity of pancreatic cancer cells to chemotherapy (Zhang, Yan, Wang, & Jin, 2019). TLR4 signaling pathways are important to determine the activity of immune checkpoint inhibitors during pancreatic cancer therapy (Topcu, Korucu, Menevse, Kocak, & Duran, 2022). TLR4 may be a potential marker for predicting the prognosis in local pancreatic cancer (Lanki et al, 2018).…”