PVT1 dependence in cancer with MYC copy-number increase

Pvt1 overexpression in mice contributes to high Myc levels due to 8q24.21 gain and to MYC-driven tumorigenesis. An RNA tied to MYC-driven cancers Many cancer cells carry extra copies of chromosomal region 8q24.21, encompassing the MYC oncogene. Anindya Bagchi and colleagues have now investigated the role of a nearby long non-coding RNA gene, PVT1 , that tends to be co-amplified. They show in engineered mouse models that PVT1 overexpression contributes to high MYC levels due to the 8q24.21 amplifications and to MYC-driven tumorigenesis. MYC and PVT1 levels are also correlated in human tumours, suggesting a similar cooperation. The authors suggest that targeting PVT1 may offer an alternative therapeutic strategy. ‘Gain’ of supernumerary copies of the 8q24.21 chromosomal region has been shown to be common in many human cancers 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 and is associated with poor prognosis 7 , 10 , 14 . The well-characterized myelocytomatosis ( MYC ) oncogene resides in the 8q24.21 region and is consistently co-gained with an adjacent ‘gene desert’ of approximately 2 megabases that contains the long non-coding RNA gene PVT1 , the CCDC26 gene candidate and the GSDMC gene. Whether low copy-number gain of one or more of these genes drives neoplasia is not known. Here we use chromosome engineering in mice to show that a single extra copy of either the Myc gene or the region encompassing Pvt1 , Ccdc26 and Gsdmc fails to advance cancer measurably, whereas a single supernumerary segment encompassing all four genes successfully promotes cancer. Gain of PVT1 long non-coding RNA expression was required for high MYC protein levels in 8q24-amplified human cancer cells. PVT1 RNA and MYC protein expression correlated in primary human tumours, and copy number of PVT1 was co-increased in more than 98% of MYC -copy-increase cancers. Ablation of PVT1 from MYC-driven colon cancer line HCT116 diminished its tumorigenic potency. As MYC protein has been refractory to small-molecule inhibition, the dependence of high MYC protein levels on PVT1 long non-coding RNA provides a much needed therapeutic target.