OXCT1 Enhances Gemcitabine Resistance Through NF-κB Pathway in Pancreatic Ductal Adenocarcinoma

Hypoxic and Acidic Tumor Microenvironment-Driven AVL9 Promotes Chemoresistance of Pancreatic Ductal Adenocarcinoma via the AVL9-IκBα-SKP1 Complex

BACKGROUND & AIMS

Gemcitabine combined with albumin-paclitaxel (AG) is a crucial therapeutic option for pancreatic ductal adenocarcinoma (PDAC). However, the response to chemotherapy is relatively poor, with rapid development of resistance. The aim of this study was to explore the mechanism of resistance to AG and to develop strategies that can sensitize the AG regimen.

METHODS

We used organoid models, patient-derived xenografts, and genetically engineered mouse models in our study. Chromatin immunoprecipitation, double luciferase assay, co-immunoprecipitation, and far-western blotting analysis were performed to investigate the mechanism. The AVL9 inhibitors were identified through protein structure analysis and molecular docking analysis, and their efficacy was verified in patient-derived xenografts, patient-derived organoids-based xenograft, and KPC models.

RESULTS

Through multistrategy screening, we identified AVL9 as a key target for AG resistance in PDAC. Its tumor-promoting effects were confirmed in our clinical cohorts. Mechanistically, HIF-1α, a hypoxia-related transcription factor, drives the expression of AVL9. AVL9 acts as a scaffold that facilitates the binding of IκBα to SKP1, leading to enhanced ubiquitination and degradation of IκBα, which further activates the nuclear factor-κB pathway. The potential AVL9-targeting inhibitor, Edotecarin, was shown to reverse AG chemo-resistance in PDAC.

CONCLUSION

AVL9 expression is driven by HIF-1α in PDAC. The physical interaction of AVL9, IκBα, and SKP1 provides a novel molecular mechanism for the abnormal activation of the nuclear factor-κB pathway. Therefore, the AVL9-targeting drug Edotecarin could be a promising therapeutic strategy for sensitizing PDAC to AG.

ATF3-induced activation of NF-κB pathway results in acquired PARP inhibitor resistance in pancreatic adenocarcinoma

PURPOSE

Olaparib, an inhibitor of poly-(adenosine diphosphate-ribose) polymerase (PARP), has been shown to have anticancer benefits in patients with pancreatic cancer who have a germline mutation in BRCA1/2. However, resistance acquired on long-term exposure to olaparib significantly impedes clinical efficacy.

METHODS

In this study, the chromatin accessibility and differentially expressed transcripts of parental and olaparib-resistant pancreatic cancer cell lines were assessed using the Assay for Transposase Accessible Chromatin with sequencing (ATAC-seq) and mRNA-seq. Detection of downstream genes regulated by transcription factors using ChIP (Chromatin immunoprecipitation assay).

RESULTS

According to pathway enrichment analysis, differentially expressed genes in olaparib-resistant cells were remarkably enriched in the NF-κB signaling pathway. With ATAC-seq, we identified chromatin regions with higher accessibility in olaparib-resistant cells and predicted a series of important transcription factors. Among them, activating transcription factor 3 (ATF3) was significantly highly expressed. Functional experiments verified that inhibition of ATF3 suppressed the NF-κB pathway significantly and restored olaparib sensitivity in olaparib-resistant cells.

CONCLUSION

Experiments in vitro and in vivo indicate ATF3 enhances olaparib resistance through the NF-κB signaling pathway, suggesting that ATF3 could be employed as an olaparib sensitivity and prognostic indicator in patients with pancreatic cancer.

ACAT2 may be a novel predictive biomarker and therapeutic target in lung adenocarcinoma

BACKGROUND

Acyl-coenzyme A cholesterol acyltransferase (ACAT) is a membrane-binding enzyme localized in the endoplasmic reticulum. ACAT2 can promote the development of colon cancer, but its efficacy in lung adenocarcinoma (LUAD) remains uncertain.

METHOD

ACAT2 expression was performed by using the TIMER2.0 database. The GEPIA database was utilized to analyze the correlation between ACAT2 expression and pathological stage of the tumor. Clinical prognosis was assessed through the Kaplan-Meier analysis. The CancerSEA database was employed to scrutinize the correlations between the ACAT2 expression and the functional status of various tumors, which were subsequently visualized as a heatmap. Furthermore, molecular interaction network analysis was performed by the STRING tool.

RESULTS

High ACAT2 expression was associated with a poor DFS and OS in LUAD patients. Cox regression analysis indicated that the poor outcomes may be related to tumor stage, nodal stage, distant metastatic stage. ACAT2 was found to play a crucial role in various biological processes, including the cell cycle, DNA repair, DNA damage response, and proliferation. Enrichment pathway analysis revealed four ACAT2 related genes, ACOX1, EHHADH, OXCT1, and DLAT.

CONCLUSION

Our study showed that ACAT2 was upregulated in LUAD, and had a worse survival. ACAT2 could be a novel predictive biomarker and therapeutic target in LUAD.

Knockdown of TANK-Binding Kinase 1 Enhances the Sensitivity of Hepatocellular Carcinoma Cells to Molecular-Targeted Drugs

The protein kinase, TANK-binding kinase 1 (TBK1), not only regulates various biological processes but also functions as an important regulator of human oncogenesis. However, the detailed function and molecular mechanisms of TBK1 in hepatocellular carcinoma (HCC), especially the resistance of HCC cells to molecular-targeted drugs, are almost unknown. In the present work, the role of TBK1 in regulating the sensitivity of HCC cells to molecular-targeted drugs was measured by multiple assays. The high expression of TBK1 was identified in HCC clinical specimens compared with paired non-tumor tissues. The high level of TBK1 in advanced HCC was associated with a poor prognosis in patients with advanced HCC who received the molecular-targeted drug, sorafenib, compared to patients with advanced HCC patients and a low level of TBK1. Overexpression of TBK1 in HCC cells induced their resistance to molecular-targeted drugs, whereas knockdown of TBK1 enhanced the cells’ sensitivity to molecular-targeted dugs. Regarding the mechanism, although overexpression of TBK1 enhanced expression levels of drug-resistance and pro-survival-/anti-apoptosis-related factors, knockdown of TBK1 repressed the expression of these factors in HCC cells. Therefore, TBK1 is a promising therapeutic target for HCC treatment and knockdown of TBK1 enhanced sensitivity of HCC cells to molecular-targeted drugs.