CSF3R-AS promotes hepatocellular carcinoma progression and sorafenib resistance through the CSF3R/JAK2/STAT3 positive feedback loop.

Antisense circular RNA is a special type of circular RNA that is derived from the antisense complementary strand of parental mRNA. However, the function of antisense circRNA in hepatocellular carcinoma (HCC) is still unclear. Here, we reported that CSF3R-AS was upregulated in HCC and correlated with a poor prognosis. CSF3R-AS promoted the proliferation, angiogenesis, and metastasis of HCC, and inhibited apoptosis. Mechanistically, CSF3R-AS has a 180-base complementary pairing sequence with its parental mRNA CSF3R, which can directly bind to CSF3R and recruit RBMS3 to stabilize its parental mRNA, and finally activate JAK2/STAT3 signaling pathway. Interestingly, STAT3 can act as a transcription factor of CSF3R-AS, which means that there is a CSF3R-AS/CSF3R/JAK2/STAT3 positive feedback loop in HCC. Finally, the CSF3R-AS/CSF3R/JAK2/STAT3 positive feedback loop was also activated in HCC sorafenib-resistant cells, and blocking this loop was expected to improve the sensitivity of HCC to sorafenib. These findings suggested that the CSF3R-AS/CSF3R/JAK2/STAT3 positive feedback loop could promote HCC progression and sorafenib resistance. Blocking this loop is expected to provide new research directions and therapy targets for HCC.