Modeling germline mutations in pineoblastoma uncovers lysosome disruption-based therapy

Philip E.d Chung ,Zhe Jiang,David Shih,Livia Garzia,Jeff C Liu,Adrian M Dubuc ,Michael D Taylor,Dong‐Yu Wang ,Marc Remke,Ronak Ghanbari-Azarnier,Bryan Li,Yaacov Ben‐David ,Seok‐Gu Kang ,Jennifer Tsui,Xiao Xiao,Deena M.a Gendoo ,Benjamin Haibe‐Kains ,Sidney Croul,Annie Huang,Ben Ho,Eldad Zacksenhaus

doi:10.1038/s41467-020-15585-2

Abstract

Pineoblastoma is a rare pediatric cancer induced by germline mutations in the tumor suppressors RB1 or DICER1. Presence of leptomeningeal metastases is indicative of poor prognosis. Here we report that inactivation of Rb plus p53 via a WAP-Cre transgene, commonly used to target the mammary gland during pregnancy, induces metastatic pineoblastoma resembling the human disease with 100% penetrance. A stabilizing mutation rather than deletion of p53 accelerates metastatic dissemination. Deletion of Dicer1 plus p53 via WAP-Cre also predisposes to pineoblastoma, albeit with lower penetrance. In silico analysis predicts tricyclic antidepressants such as nortriptyline as potential therapeutics for both pineoblastoma models. Nortriptyline disrupts the lysosome, leading to accumulation of non-functional autophagosome, cathepsin B release and pineoblastoma cell death. Nortriptyline further synergizes with the antineoplastic drug gemcitabine to effectively suppress pineoblastoma in our preclinical models, offering new modality for this lethal childhood malignancy.

Highlights

Pineoblastoma is a rare pediatric cancer induced by germline mutations in the tumor suppressors RB1 or DICER1
We have made the fortuitous discovery that the whey acidic protein (WAP) promoter Cre deleter line (WAP-Cre)[13], commonly used to target mammary lobuloalveolar progenitors during the estrous cycle and pregnancy, is expressed in the pineal gland in both male and female mice, and that WAPCre:Rbflox/flox:p53flox/flox and WAP-Cre:Rbflox/flox:p53lsl_R270H/flox mice develop metastatic PBs that resemble the human disease with short latency and 100% penetrance
Disruption of Dicer[1] plus p53 induces PB, though with longer latency and reduced penetrance as observed in children. These results demonstrate the utility of the WAP-Cre transgene for modeling diverse types of PBs, and suggesting similar cell of origin for RB1- and DICER1deficient PB

Summary

Introduction

Pineoblastoma is a rare pediatric cancer induced by germline mutations in the tumor suppressors RB1 or DICER1. We report that inactivation of Rb plus p53 via a WAP-Cre transgene, commonly used to target the mammary gland during pregnancy, induces metastatic pineoblastoma resembling the human disease with 100% penetrance. We have made the fortuitous discovery that the whey acidic protein (WAP) promoter Cre deleter line (WAP-Cre)[13], commonly used to target mammary lobuloalveolar progenitors during the estrous cycle and pregnancy, is expressed in the pineal gland in both male and female mice, and that WAPCre:Rbflox/flox:p53flox/flox and WAP-Cre:Rbflox/flox:p53lsl_R270H/flox mice develop metastatic PBs that resemble the human disease with short latency and 100% penetrance. Disruption of Dicer[1] plus p53 induces PB, though with longer latency and reduced penetrance as observed in children These results demonstrate the utility of the WAP-Cre transgene for modeling diverse types of PBs, and suggesting similar cell of origin for RB1- and DICER1deficient PB. Deletion of the floxed Rb and p53 alleles, and loss of protein expression in these tumors were confirmed (Fig. 1e)

Methods

Results

Conclusion