Targeted therapy based on ubiquitin-specific proteases, signalling pathways and E3 ligases in non-small-cell lung cancer

Exploiting E3 ligases for lung cancer therapy: The promise of DCAF-PROTACs

Lung cancer remains the leading cause of cancer-related mortality, underscoring the urgent need for novel therapeutic strategies. One emerging approach in drug development targets oncogenic proteins via the ubiquitin-proteasome system (UPS), specifically through proteolysis-targeting chimeras (PROTACs). Among the various E3 ligase complexes, the CRL4 complex-comprising DDB1 and CUL4-associated factors (DCAFs)-has garnered attention for its roles in cellular homeostasis, DNA repair, and oncogenesis. This review explores the therapeutic potential of DCAF-based PROTACs (DCAF-PROTACs) in lung cancer by focusing on the substrate receptors DCAF13, DCAF15, and DCAF16, which mediate CRL4-dependent ubiquitination. We first discuss the dysregulation of DCAF proteins in lung cancer and then elaborate on their mechanistic role in facilitating target-specific protein degradation via DCAF-E3 ligase complexes. Recent studies show that DCAF-PROTACs selectively degrade oncogenic proteins, addressing treatment resistance and tumor heterogeneity. Notably, DCAF13 promotes lung adenocarcinoma by destabilizing p53, while DCAF15-PROTACs target and degrade RBM39 effectively. Additionally, the development of electrophilic PROTACs targeting DCAF16 presents a promising avenue for degrading nuclear proteins. Despite these advancements, several challenges must be addressed prior to clinical translation, including issues related to drug bioavailability, stability, and emerging resistance mechanisms. This review also explores the potential of combination therapies, particularly with immunotherapy, to enhance tumor specificity and therapeutic efficacy. Ultimately, the deployment of DCAF-PROTACs marks a significant advancement in precision oncology, offering a novel and targeted approach to protein degradation-based cancer treatment.

Exploring the cancerous nexus: the pivotal and diverse roles of USP39 in cancer development

The ubiquitin-proteasome system enables post-transcriptional protein modification and is a major pathway for the degradation of most of them in eukaryotic cells. Among these, the ubiquitin-specific protease (USP) family is the most extensively studied. As an important member of the USP family, ubiquitin-specific protease 39 (USP39) plays an essential role in RNA splicing and protein regulation. This review comprehensively summarizes the structural characteristics and molecular functions of USP39, emphasizing its pivotal role in the regulation of cellular processes. Dysregulation of USP39 is closely associated with the progression of various cancers through mechanisms such as immune evasion, modulation of oncogenic signaling pathways, and altered RNA splicing. These processes impact key aspects of cancer biology, including proliferation, metastasis, and therapy resistance, underscoring the broad implications of USP39 in tumor progression. Recent studies position USP39 as a promising target for cancer treatment. Future research should explore its upstream regulatory networks, develop small-molecule inhibitors, and evaluate its potential for precision oncology. This review integrates the latest insight into USP39, providing a foundation for its clinical application in cancer therapy.

Ubiquitin-Specific Protease Inhibitors for Cancer Therapy: Recent Advances and Future Prospects

Cancer management has traditionally depended on chemotherapy as the mainstay of treatment; however, recent advancements in targeted therapies and immunotherapies have offered new options. Ubiquitin-specific proteases (USPs) have emerged as promising therapeutic targets in cancer treatment due to their crucial roles in regulating protein homeostasis and various essential cellular processes. This review covers the following: (1) the structural and functional characteristics of USPs, highlighting their involvement in key cancer-related pathways, and (2) the discovery, chemical structures, mechanisms of action, and potential clinical implications of USP inhibitors in cancer therapy. Particular attention is given to the role of USP inhibitors in enhancing cancer immunotherapy, e.g., modulation of the tumor microenvironment, effect on regulatory T cell function, and influence on immune checkpoint pathways. Furthermore, this review summarizes the current progress and challenges of clinical trials involving USP inhibitors as cancer therapy. We also discuss the complexities of achieving target selectivity, the ongoing efforts to develop more specific and potent USP inhibitors, and the potential of USP inhibitors to overcome drug resistance and synergize with existing cancer treatments. We finally provide a perspective on future directions in targeting USPs, including the potential for personalized medicine based on specific gene mutations, underscoring their significant potential for enhancing cancer treatment. By elucidating their mechanisms of action, clinical progress, and potential future applications, we hope that this review could serve as a useful resource for both basic scientists and clinicians in the field of cancer therapeutics.

Clinically relevant stratification of lung squamous carcinoma patients based on ubiquitinated proteasome genes for 3P medical approach

Relevance

The proteasome is a crucial mechanism that regulates protein fate and eliminates misfolded proteins, playing a significant role in cellular processes. In the context of lung cancer, the proteasome's regulatory function is closely associated with the disease's pathophysiology, revealing multiple connections within the cell. Therefore, studying proteasome inhibitors as a means to identify potential pathways in carcinogenesis and metastatic progression is crucial in in-depth insight into its molecular mechanism and discovery of new therapeutic target to improve its therapy, and establishing effective biomarkers for patient stratification, predictive diagnosis, prognostic assessment, and personalized treatment for lung squamous carcinoma in the framework of predictive, preventive, and personalized medicine (PPPM; 3P medicine).

Methods

This study identified differentially expressed proteasome genes (DEPGs) in lung squamous carcinoma (LUSC) and developed a gene signature validated through Kaplan-Meier analysis and ROC curves. The study used WGCNA analysis to identify proteasome co-expression gene modules and their interactions with the immune system. NMF analysis delineated distinct LUSC subtypes based on proteasome gene expression patterns, while ssGSEA analysis quantified immune gene-set abundance and classified immune subtypes within LUSC samples. Furthermore, the study examined correlations between clinicopathological attributes, immune checkpoints, immune scores, immune cell composition, and mutation status across different risk score groups, NMF clusters, and immunity clusters.

Results

This study utilized DEPGs to develop an eleven-proteasome gene-signature prognostic model for LUSC, which divided samples into high-risk and low-risk groups with significant overall survival differences. NMF analysis identified six distinct LUSC clusters associated with overall survival. Additionally, ssGSEA analysis classified LUSC samples into four immune subtypes based on the abundance of immune cell infiltration with clinical relevance. A total of 145 DEGs were identified between high-risk and low-risk score groups, which had significant biological effects. Moreover, PSMD11 was found to promote LUSC progression by depending on the ubiquitin-proteasome system for degradation.

Conclusions

Ubiquitinated proteasome genes were effective in developing a prognostic model for LUSC patients. The study emphasized the critical role of proteasomes in LUSC processes, such as drug sensitivity, immune microenvironment, and mutation status. These data will contribute to the clinically relevant stratification of LUSC patients for personalized 3P medical approach. Further, we also recommend the application of the ubiquitinated proteasome system in multi-level diagnostics including multi-omics, liquid biopsy, prediction and targeted prevention of chronic inflammation and metastatic disease, and mitochondrial health-related biomarkers, for LUSC 3PM practice.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-024-00352-w.