MicroRNA-139 suppresses hepatocellular carcinoma cell proliferation and migration by directly targeting Topoisomerase I

Circular RNA circIPO11 drives self-renewal of liver cancer initiating cells via Hedgehog signaling

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most intractable tumors in the world due to its high rate of recurrence and heterogeneity. Liver cancer initiating cells also called cancer stem cells (CSCs) play a critical role in resistance against typical therapy and high tumor-initiating potential. However, the role of the novel circular RNA (circRNA) circIPO11 in the maintenance of liver cancer initiating cells remains elusive.

METHODS

CircRNAs highly conserved in humans and mice were identified from 3 primary HCC samples by circRNA array. The expression and function of circIPO11 were further evaluated by Northern blot, limiting dilution xenograft analysis, chromatin isolation by RNA purification-PCR assay (ChIRP) and HCC patient-derived tumor cells (PDC) models. CircIpo11 knockout (KO) mice were generated by a CRISPR/Cas9 technology.

RESULTS

CircIPO11 is highly expressed in HCC tumor tissues and liver CSCs. CircIPO11 is required for the self-renewal maintenance of liver CSCs to initiate HCC development. Mechanistically, circIPO11 recruits TOP1 to GLI1 promoter to trigger its transcription, leading to the activation of Hedgehog signaling. Moreover, GLI1 is also highly expressed in HCC tumor tissues and liver CSCs, and TOP1 expression levels positively correlate with the metastasis, recurrence and survival of HCC patients. Additionally, circIPO11 knockout in mice suppresses the progression of chemically induced liver cancer development.

CONCLUSION

Our findings reveal that circIPO11 drives the self-renewal of liver CSCs and promotes the propagation of HCC via activating Hedgehog signaling pathway. Antisense oligonucleotides (ASOs) against circIPO11 combined with TOP1 inhibitor camptothecin (CPT) exert synergistic antitumor effect. Therefore, circIPO11 and the Hedgehog signaling pathway may provide new potential targets for the treatment of HCC patients.

MicroRNA (MiR)-301a-3p regulates the proliferation of esophageal squamous cells via targeting PTEN

Human esophageal carcinoma (EC) is a common cancer, which leads to many deaths worldwide every year. Our study aimed to explore the mechanism of miR-301a-3p regulating the proliferation of esophageal squamous cell carcinoma (ESCC) cells. We had collected ESCC tissues and adjacent normal esophageal tissues from 47 patients. The relative levels of miR-301a-3p/U6 in ESCC tissues and cells were analyzed by real-time PCR. And we measured the relative protein levels of PTEN, BCL-2, BAX, and p-AKT/AKT by Western blot. Eca-109 cell proliferation was detected by MTT assay and colony formation. Compared with adjacent normal esophageal tissues, the relative level of miR-301a-3p/U6 was elevated in ESCC tissues. MiR-301a-3p could facilitate ESCC cell proliferation. And miR-301a-3p directly bind to PTEN 3ʹ-UTR and negatively regulated PTEN protein expression. Moreover, silencing PTEN could reversed inhibited proliferation of Eca-109 cells induced by miR-301a-3p inhibitor, while overexpression PTEN could reversed enhanced proliferation of Eca-109 cells induced by miR-301a-3p mimic. Taken together, miR-301a-3p promoted ESCC cell proliferation by supressing PTEN.