Two circPPFIA1s negatively regulate liver metastasis of colon cancer via miR-155-5p/CDX1 and HuR/RAB36

Abstract

Background Circular RNAs (circRNAs) play a critical role in colorectal cancer (CRC) progression, including metastasis. However, the detailed molecular mechanism is not fully understood. Methods Differentially expressed circRNAs between primary KM12C and liver metastatic KM12L4 colon cancer cells were identified by microarray. The expression of circRNAs was measured by semi-quantitative (semi-qPCR) and real time-quantitative PCR (RT-qPCR). Metastatic potential including invasive and migratory abilities, and liver metastasis were examined by transwell assays and intrasplenic injection, respectively. CircPPFIA1-associated microRNA (miRNA) and RNA-binding protein (RBP) were screened by an antisense oligonucleotide (ASO) pulldown experiment. The effects of circPPFIA1 on target gene expression were evaluated by RT-qPCR and western blot analyses. Results By analyzing circRNA microarray data, we identified two anti-metastatic circRNAs generated from PPFIA1 with different length, which named circPPFIA1-L (long) and -S (short). They were significantly downregulated in liver metastatic KM12L4 cells compared to primary KM12C cells. The knockdown of circPPFIA1s in KM12C enhanced metastatic potential and increased liver metastasis. Conversely, overexpression of circPPFIA1s weakened metastatic potential and inhibited liver metastasis. circPPFIA1s were found to function as sponges of oncogenic miR-155-5p and Hu antigen R (HuR) by an ASO pulldown experiment. circPPFIA1s upregulated tumor-suppressing CDX1 expression and conversely downregulated oncogenic RAB36 by decoying miR-155-5p and by sequestering HuR, respectively. Conclusion Our findings demonstrate that circPPFIA1s inhibit the liver metastasis of CRC via the miR-155-5p/CDX1 and HuR/RAB36 pathways.

Effects of hsa_circ_0074854 on colorectal cancer progression, construction of a circRNA–miRNA–mRNA network, and analysis of immune infiltration

“…After performing differential expression analysis on the database data, we identified four circRNAs that met the criteria, and we selected has_circ_0074854 for further investigation. Multiple studies have demonstrated that circRNAs can act as miRNA sponges to positively regulate downstream gene expression (Sang et al 2019 ; Wang et al 2021a , b , c ; Liu et al 2019 ; Ji et al 2022 ; Hu et al 2022 ). Therefore, we predicted the potential miRNAs targeted by circRNA.…”

Circular RNAs in hepatocellular carcinoma: biogenesis, function, and pathology

“…For instance, circPPFIA1s are generated from PPFIA1 with different length, including circPPFIA1-L (long) and -S (short). CircPPFIA1s binds to HuR and destroys the mRNA stability effect of HuR on oncogenic RAB36, thus decreasing RAB36 expression and inhibiting the liver metastasis of colorectal cancer (Ji et al, 2022). CircBACH1 is able to directly interact with HuR and facilitate HuR translocation to the cytoplasm, resulting in decreased p27 translation and increased HCC cell proliferation .…”

Circular RNAs: Promising Treatment Targets and Biomarkers of Ischemic Stroke

“…Upon binding with circPPFIA1s, HuR becomes unable to bind with the mRNA of the Member RAS oncogene family 36 (RAB36). Consequently, the stability of RAB36 mRNA decreases, leading to a reduction in RAB36 protein expression, which inhibits the metastasis of colorectal cancer [ 19 ]. In another case, circTHBS1 can strengthen the HuR-mediated mRNA stability of INHBA, which subsequently activated the TGF-β pathway [ 20 ].…”