Ubiquitin-specific peptidase 17 promotes cisplatin resistance via PI3K/AKT activation in non-small cell lung cancer

The roles of KLHL family members in human cancers

The Kelch-like (KLHL) family members consist of three domains: bric-a-brac, tramtrack, broad complex/poxvirus and zinc finger domain, BACK domain and Kelch domain, which combine and interact with Cullin3 to form an E3 ubiquitin ligase. Research has indicated that KLHL family members ubiquitinate target substrates to regulate physiological and pathological processes, including tumorigenesis and progression. KLHL19, a member of the KLHL family, is associated with tumorigenesis and drug resistance. However, the regulation and cross talks of other KLHL family members, which also play roles in cancer, are still unclear. Our review mainly explores studies concerning the roles of other KLHL family members in tumor-related regulation to provide novel insights into KLHL family members.

A Case Series Exploration of Multi-Regional Expression Heterogeneity in Triple-Negative Breast Cancer Patients

Extensive intratumoral heterogeneity (ITH) is believed to contribute to therapeutic failure and tumor recurrence, as treatment-resistant cell clones can survive and expand. However, little is known about ITH in triple-negative breast cancer (TNBC) because of the limited number of single-cell sequencing studies on TNBC. In this study, we explored ITH in TNBC by evaluating gene expression-derived and imaging-derived multi-region differences within the same tumor. We obtained tissue specimens from 10 TNBC patients and conducted RNA sequencing analysis of 2-4 regions per tumor. We developed a novel analysis framework to dissect and characterize different types of variability: between-patients (inter-tumoral heterogeneity), between-patients across regions (inter-tumoral and region heterogeneity), and within-patient, between-regions (regional intratumoral heterogeneity). We performed a Bayesian changepoint analysis to assess and classify regional variability as low (convergent) versus high (divergent) within each patient feature (TNBC and PAM50 subtypes, immune, stroma, tumor counts and tumor infiltrating lymphocytes). Gene expression signatures were categorized into three types of variability: between-patients (108 genes), between-patients across regions (183 genes), and within-patients, between-regions (778 genes). Based on the between-patient gene signature, we identified two distinct patient clusters that differed in menopausal status. Significant intratumoral divergence was observed for PAM50 classification, tumor cell counts, and tumor-infiltrating T cell abundance. Other features examined showed a representation of both divergent and convergent results. Lymph node stage was significantly associated with divergent tumors. Our results show extensive intertumoral heterogeneity and regional ITH in gene expression and image-derived features in TNBC. Our findings also raise concerns regarding gene expression based TNBC subtyping. Future studies are warranted to elucidate the role of regional heterogeneity in TNBC as a driver of treatment resistance.

Hypoxic Microenvironment-Induced Reduction in PTEN-L Secretion Promotes Non-Small Cell Lung Cancer Metastasis through PI3K/AKT Pathway

Objective

Lung cancer is the leading cause of cancer-related deaths worldwide. The aim of this study was to investigate the effects of hypoxic microenvironment on PTEN-L secretion and the effects of PTEN-L on the metastasis of non-small cell lung cancer (NSCLC) and the potential mechanisms.

Methods

The expression levels of PTEN-L in NSCLC tissues, cells, and cell culture media were detected. The transfection of PTEN-L overexpression construct or HIF-1α-siRNAs was conducted to manipulate the expression of PTEN-L or HIF-1α. NSCLC cells were introduced into 200 μM CoCl2 medium for 72 hours under 37°C to simulate hypoxia. The proliferation and apoptosis of the A549 cells were determined by the Cell Counting Kit-8 assay and Annexin V-FITC/PI-stained flow cytometry assay, respectively. Wound healing assay and transwell invasion assay were used to measure the migration and invasion of A549 cells. The protein expression of PTEN, PTEN-L, PI3K/AKT pathway-related proteins, and HIF-1α was detected by Western blot.

Results

PTEN and PTEN-L are downregulated in lung cancer tissues and cells. The protein expression of PTEN-L in the culture medium of lung cancer cell lines is decreased. The hypoxic microenvironment inhibits PTEN-L secretion. The low level of PTEN-L promotes cell proliferation, migration, and invasion, as well as inhibits apoptosis of A549 cells. The overexpression of PTEN-L attenuated the activation of the PI3K/AKT pathway by the hypoxic microenvironment. The knockdown of HIF-1α upregulates PTEN-L secretion under hypoxia.

Conclusions

The hypoxic microenvironment inhibits PTEN-L secretion and thus activates PI3K/AKT pathway to induce proliferation, migration, and invasion promotion, and apoptosis inhibition in NSCLC cells.

Dimethylaminomicheliolide Sensitizes Cancer Cells to Radiotherapy for Synergistic Combination with Immune Checkpoint Blockade

Radiotherapy (RT) has demonstrated synergy with immune checkpoint blockade (ICB) in preclinical models. However, its potential as an immunoadjuvant is limited by low immunogenicity at low radiation doses and immunosuppression at high radiation doses. It is hypothesized that radiosensitizers can enhance both the anticancer and immunogenic effects of low-dose radiation. Herein the authors report the antitumor immunity of combined RT and immunotherapy with dimethylaminomicheliolide (DMAMCL), a prodrug of the anti-inflammatory sesquiterpene lactone micheliolide (MCL). DMAMCL sensitized cancer cells to a single fraction of RT in vitro by inducing apoptosis and DNA double-strand breaks. DMAMCL with 5 fractions of 2 Gy focal X-ray irradiation led to significant anticancer efficacy in subcutaneous and spontaneous models of murine cancer. DMAMCL-sensitized RT upregulated programmed death-ligand 1 (PD-L1) expression in the tumors. Combination of DMAMCL-sensitized RT with anti-PD-L1 ICB significantly enhanced antitumor efficacy by increasing tumor-infiltrating CD4+ and CD8+ T cells and establishing immune memory.

The role of the deubiquitinating enzyme DUB3/USP17 in cancer: a narrative review

The balance between ubiquitination and deubiquitination is critical for the degradation, transport, localization, and activity of proteins. Deubiquitinating enzymes (DUBs) greatly contribute to the balance of ubiquitination and deubiquitination, and they have been widely studied due to their fundamental role in cancer. DUB3/ubiquitin-specific protease 17 (USP17) is a type of DUB that has attracted much attention in cancer research. In this review, we summarize the biological functions and regulatory mechanisms of USP17 in central nervous system, head and neck, thoracic, breast, gastrointestinal, genitourinary, and gynecologic cancers as well as bone and soft tissue sarcomas, and we provide new insights into how USP17 can be used in the management of cancer.