Inhibition of Ubiquitin Specific Protease 1 Sensitizes Colorectal Cancer Cells to DNA-Damaging Chemotherapeutics

Abstract

Mutations and altered expression of deubiquitinating enzymes (DUBs) have been found associated with many human diseases including cancers. In this study, Ubiquitin specific protease 1 (USP1) expression was found significantly increased in some colorectal cancers (CRC). The elevated USP1 level was associated with short overall survival of patients and with advanced stages of cancers. In cultured CRC cells, knockdown of USP1 induced growth arrest at G 2 /M of cell cycle and reduced the expression of anti-apoptotic proteins Bcl-2 and Mcl-1. Its knockdown also led to reduction of DNA-repair related substrates FANCD2 and ID1. Further investigations found that small molecular inhibitor of USP1 ML323 sensitized CRC cells to DNA-targeting chemotherapeutics, including doxorubicin, TOPI/II inhibitors, and PARP inhibitor, but not to 5-Fu. These results indicate that USP1 plays a critical in colorectal cancer cell survival and is a promising target for anti-colorectal cancer chemotherapy. Targeting USP1 may represent an effective strategy to regulate the DNA-repairing system.

Inhibition of BMI-1 Induces Apoptosis through Downregulation of DUB3-Mediated Mcl-1 Stabilization

“…Protein ubiquitination via the regulation of UPS plays a crucial role in anti-apoptotic protein degradation, including Bcl-2, Bcl-xL, and Mcl-1, resulting in the induction of cancer cell death [ 28 ]. Because E3 ubiquitin ligases and DUBs are associated with protein stability through the UPS pathway, we investigated the alteration of these enzymes, which are capable of regulating Mcl-1 [ 29 , 30 , 31 , 32 , 33 ]. As shown in Figure 4 B,C, Mcl-1-targeting E3 ligases (FBW7 and β-TrCP) were not altered by PTC596, whereas USP1 and DUB3 were decreased.…”

Mutation of aspartic acid 199 in USP1 disrupts its deubiquitinating activity and impairs DNA repair

“…Elevated expression of USP1 has been reported in several human cancers [19–23,37], suggesting that USP1 functions as an oncogene. However, because as USP1 is critical for deubiquitination of PCNA [11], USP1 activity could impact on PCNA‐dependent TLS [10,12,38,39].…”

“…USP1 inhibition by selective USP1 inhibitors sensitized lung cancer cells to cisplatin treatment and induced apoptosis in multiple myeloma cells [16–18]. Recently, it has been reported that the expression of USP1 is elevated in several human cancers, such as osteosarcoma, non‐small‐cell lung cancer (NSCLC), and colorectal cancers [19–23], suggesting that USP1 could be a promising anticancer target for at least certain types of human cancers. At present, a total of 297 somatic mutations in USP1 were identified by COSMIC (Catalogue Of Somatic Mutations In Cancer) mutation database (https://cancer.sanger.ac.uk/cosmic/).…”

Inhibition of DNA Repair in Cancer Therapy: Toward a Multi-Target Approach

“…DNA cross-linking agents [180][181][182] USP1/UAF1 ML323 Topoisomerase I and II inhibitors PARP1 inhibition [183,184] For each target it is reported: name of the drugs currently in analysis; combination of target inhibition and classic anti-cancer therapy under study; possible synthetic lethality interaction; references.…”

“…Several molecules that inhibit specific components of the FA pathway have been identified acting at different levels; for instance, phenylbutyrate sensitizes head and neck cancer cells to cisplatin by reducing the expression of FANCS [179], curcumin acts on the mono-ubiquitination step of FANCD2 sensitizing ovarian and breast tumor cell lines to cisplatin and glioma cell lines to alkylating agents, also MLN4924 suppresses FANCD2 mono-ubiquitination sensitizing cells to DNA ICLs agents [180][181][182] (Table 6). The USP1/UAF1 complex has been identified as a druggable target: ML323 inhibits it, leading to sensitization of colorectal cancer, non-small cell lung cancer, and osteosarcoma cells to DNA-damaging chemotherapeutics and PARP inhibitors (Table 6); inhibiting this complex also compromises TLS due to reduced deubiquitination of PCNA, thus this drug could act on FA by simultaneously targeting two steps [183,184].…”