<i>PHAROH</i> lncRNA regulates Myc translation in hepatocellular carcinoma via sequestering TIAR.

Yu, Allen T; Berasain, Carmen; Bhatia, Sonam; Rivera, Keith; Liu, Bodu; Rigo, Frank; Pappin, Darryl J; Spector, David L · Elife · 2021

basic_science · Level V

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Abstract

Hepatocellular carcinoma, the most common type of liver malignancy, is one of the most lethal forms of cancer. We identified a long non-coding RNA, <i>Gm19705</i>, that is overexpressed in hepatocellular carcinoma and mouse embryonic stem cells. We named this RNA <i><u>P</u>luripotency and <u>H</u>epatocyte <u>A</u>ssociated <u>R</u>NA <u>O</u>verexpressed in <u>H</u>CC</i>, or <i>PHAROH</i>. Depletion of <i>PHAROH</i> impacts cell proliferation and migration, which can be rescued by ectopic expression of <i>PHAROH</i>. RNA-seq analysis of <i>PHAROH</i> knockouts revealed that a large number of genes with decreased expression contain a <i>Myc</i> motif in their promoter. MYC is decreased in knockout cells at the protein level, but not the mRNA level. RNA-antisense pulldown identified nucleolysin TIAR, a translational repressor, to bind to a 71-nt hairpin within <i>PHAROH</i>, sequestration of which increases MYC translation. In summary, our data suggest that <i>PHAROH</i> regulates MYC translation by sequestering TIAR and as such represents a potentially exciting diagnostic or therapeutic target in hepatocellular carcinoma.

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