The long noncoding RNA lnc-FANCI-2 restricts RAS signaling and phosphorylation of Akt and Erk in HPV16-infected cervical cancer cells

We recently discovered increased expression of a cytoplasmic long noncoding RNA, lnc-FANCI-2, coinciding with cervical lesion progression from CIN1, CIN2-3 to cervical cancer. Viral E7 of high-risk HPVs and host transcription factor YY1 are two major factors promoting lnc-FANCI-2 expression. To explore possible roles of lnc-FANCI-2 in HPV-induced cervical carcinogenesis, we ablated the expression of lnc-FANCI-2 in the HPV16-positive cervical cancer cell line, CaSki. Knock-out (KO) single cell clones expressed HPV16 oncogenes normally but displayed altered cell morphology and reduced proliferation and migration when compared with the parental cells. Proteomic profiling of cytosolic and secreted proteins from the parental and KO cells showed that lnc-FANCI-2 regulates expression of a subset of cell surface and adhesion-related proteins, including inhibition of MCAM, PODXL2 and ECM1 and increased levels of ADAM8 and TIMP2. RNA-seq analyses revealed that, relative to the parental cells, KO cells exhibited significantly increased RAS signaling but decreased IFN pathways. In KO cells, phosphorylated Akt and Erk1/2, two important RAS pathway effectors, were increased more than 3-fold, accompanied by increase of MCAM, VIM, and CCND2 (cyclin D2) and decrease of RAC3. Accordingly, high levels of lnc-FANCI-2 and lower levels of MCAM in cervical cancer patients are associated with improved survival. We found that lnc-FANCI-2 in CaSki cells interacts specifically with 32 host proteins, including H13, HNRH1, K1H1, MAP4K4, and RNPS1, and knockdown of MAP4K4 led to decreased phosphorylation of Akt and Erk1/2. In summary, a key function of lnc-FANCI-2 is to regulate RAS signaling, thereby affecting cervical cancer outcome. ### Competing Interest Statement The authors have declared no competing interest. NCBI GEO database Accession# GSE190904 for CaSki cell RNA-seq.