The acidic microenvironment promotes pancreatic cancer progression via the lncRNA-LOC100507424/E2F1/FOXM1 axis

Abstract

Pancreatic cancer is highly aggressive and sensitive to acidic microenvironments, which promote cancer cell survival and invasion. Long non-coding RNAs (lncRNAs) play crucial roles in cancer biology, helping cells adapt to microenvironmental changes, but their functions in the acidic microenvironment of pancreatic cancer are understudied. This study investigated the role of lncRNA LOC100507424 in pancreatic cancer, previously linked to glioma stem cells. Clinical specimens and cell line models cultured under acidic conditions showed that LOC100507424 was upregulated in pancreatic cancer tissues and further increased in acidic environments. Functional assays demonstrated that knockdown of LOC100507424 inhibited cell proliferation, invasion and metastasis. Mechanistically, LOC100507424 transcriptionally regulated FOXM1 expression through its interaction with E2F1. In vivo studies confirmed that LOC100507424 promoted tumor growth in nude mice. These findings highlight the significance of lncRNAs in the acidic microenvironment of pancreatic cancer and suggest potential therapeutic targets.

Keywords: Acidic microenvironment; Cancer progression; LOC100507424; LncRNA; Pancreatic cancer.

Fig. 1

LOC100507424 is highly expressed in human pancreatic cancer tissues with acidic microenvironment pancreatic cancer cell lines. A: Differential clustering heatmap showing high expression of LOC100507424 in pancreatic cancer tissues from 3 patients, including 3 pancreatic cancer samples and 3 adjacent non-tumor tissues. B: Graphical representation of GO and KEGG enrichment analysis. C: Nucleoplasmic separation assay localizing LOC100507424. D: Upregulation of LOC100507424 expression in acidic microenvironment

Fig. 2

Acidic microenvironment promotes pancreatic cancer development by upregulating LOC100507424. A: Validation of transfection efficiency. B-C: CCK-8 and colony formation assays for assessing cell viability and proliferation. D: Scratch assay for evaluating cell migration ability. E: Transwell assay for measuring cell invasive capacity. Scale of 200 μm

Fig. 3

Transcriptional regulation of FOXM1 by LOC100507424. A-B: GEPIA analysis showing high FOXM1 expression in pancreatic cancer tissues and its correlation with poor prognosis. C: Dual luciferase activity assay showing the effect of LOC100507424 on FOXM1 promoter activity. D: Schematic diagram of primers 1–7 used for promoter region analysis. E: Electrophoresis gel image of ChIRP assay products. F: ChIRP assay identifying specific binding sites of LOC100507424 on the FOXM1 promoter. G: RT-qPCR detecting FOXM1 expression

Fig. 4

FOXM1: role in acidic microenvironment-promotes pancreatic cancer development. A: Verification of transfection efficiency. B-C: Assessment of cell viability and proliferation using CCK-8 and colony formation assays. D: Evaluation of cell migration ability using the scratch assay. E: Evaluation of cell invasion ability using the transwell assay. Scale of 200 μm

Fig. 5

LOC100507424 interacts with E2F1. A: catRAPID prediction of LOC100507424 binding to E2F1. B: Silver staining image from RNA pull-down assay. C: Western blot analysis of RNA pull-down products. D: Electropherogram from RIP assay. E: Enrichment analysis of RIP products. F: GEPIA analysis showing the correlation between E2F1 and FOXM1. G-H: Validation of transfection efficiency. I: ChIP analysis of E2F1 binding to the FOXM1 promoter in sicon vs. siLOC100507424 cells

Fig. 6

Promotion of pancreatic cancer development by the LOC100507424-FOXM1 axis in acidic microenvironments is dependent on E2F1. A-B: Assessment of cell viability and proliferation using CCK-8 and colony formation assays. C: Evaluation of cell migration using the scratch assay. D: Evaluation of cell invasion using the transwell assay. E: RT-qPCR analysis of FOXM1 expression. Scale of 200 μm

Fig. 7

In Vivo, LOC100507424 Promotes Pancreatic Cancer Development. A: Verification of silencing efficiency in stably transfected PANC-1. B: Illustration of tumor mass. C: Changes in tumor volume. D: Tumor mass weight. E: In vivo validation of LOC100507424 silencing efficiency. F: FOXM1, CD206 and Arginase-1 expression detected by RT-qPCR in vivo. G: IHC staining illustration. H: Ki67 and E-cadherin expression levels (n = 5). Scale of 100 μm