P53 destabilizing protein skews asymmetric division and enhances NOTCH activation to direct self-renewal of TICs

Hye Yeon Choi,Mengmei Zheng,Da-Wei Yeh,Stanley M Tahara,Ratna B Ray,Dinesh Babu Uthaya Kumar,Chia-Lin Chen,Keigo Machida,Yi Kou,Peleg Winer,Lin Chen,Hidekazu Tsukamoto,Hifzur R Siddique,Chengyu Liang,Tatsuya Machida,Alejandro Pita,Vasu Punj,Linda Sher

doi:10.1038/s41467-020-16616-8

Abstract

Tumor-initiating stem-like cells (TICs) are defective in maintaining asymmetric cell division and responsible for tumor recurrence. Cell-fate-determinant molecule NUMB-interacting protein (TBC1D15) is overexpressed and contributes to p53 degradation in TICs. Here we identify TBC1D15-mediated oncogenic mechanisms and tested the tumorigenic roles of TBC1D15 in vivo. We examined hepatocellular carcinoma (HCC) development in alcohol Western diet-fed hepatitis C virus NS5A Tg mice with hepatocyte-specific TBC1D15 deficiency or expression of non-phosphorylatable NUMB mutations. Liver-specific TBC1D15 deficiency or non-p-NUMB expression reduced TIC numbers and HCC development. TBC1D15–NuMA1 association impaired asymmetric division machinery by hijacking NuMA from LGN binding, thereby favoring TIC self-renewal. TBC1D15–NOTCH1 interaction activated and stabilized NOTCH1 which upregulated transcription of NANOG essential for TIC expansion. TBC1D15 activated three novel oncogenic pathways to promote self-renewal, p53 loss, and Nanog transcription in TICs. Thus, this central regulator could serve as a potential therapeutic target for treatment of HCC.

Highlights

Tumor-initiating stem-like cells (TICs) are defective in maintaining asymmetric cell division and responsible for tumor recurrence
The percentage of CD133+ TICs in total tumor cells of Alb::CreERT2;Tbc1d15f/f;NA5A mice was decreased by 70% (Fig. 1h, top)
We previously showed that the N-terminal region of TBC1D15 (NTBC1D15, aa 2–158) containing the 50 aa Canoe homology domain is indispensable for NUMB association and p53 degradation[9]

Summary

Introduction

Tumor-initiating stem-like cells (TICs) are defective in maintaining asymmetric cell division and responsible for tumor recurrence. We tested first if hepatocyte-specific TBC1D15 deficiency prevented loss of p53 and liver tumor development by using the inducible Alb::CreERT approach described above (Fig. 1b). Based on this meta-analysis we examined the expression of NANOG, TBC1D15, p53, N1ICD, and p-(S265) NUMB in liver protein extracts of normal human subjects vs patients with alcoholic cirrhosis/hepatitis (Fig. 3b, c).

Results

Conclusion