KLHL18 inhibits the proliferation, migration, and invasion of non-small cell lung cancer by inhibiting PI3K/PD-L1 axis activity

Decoding dynamic miRNA:ceRNA interactions unveils therapeutic insights and targets across predominant cancer landscapes

Competing endogenous RNAs play key roles in cellular molecular mechanisms through cross-talk in post-transcriptional interactions. Studies on ceRNA cross-talk, which is particularly dependent on the abundance of free transcripts, generally involve large- and small-scale studies involving the integration of transcriptomic data from tissues and correlation analyses. This abundance-dependent nature of ceRNA interactions suggests that tissue- and condition-specific ceRNA dynamics may fluctuate. However, there are no comprehensive studies investigating the ceRNA interactions in normal tissue, ceRNAs that are lost and/or appear in cancerous tissues or their interactions. In this study, we comprehensively analyzed the tumor-specific ceRNA fluctuations observed in the three highest-incidence cancers, LUAD, PRAD, and BRCA, compared to healthy lung, prostate, and breast tissues, respectively. Our observations pertaining to tumor-specific competing endogenous RNA (ceRNA) interactions revealed that, in the cases of lung adenocarcinoma (LUAD), prostate adenocarcinoma (PRAD), and breast invasive carcinoma (BRCA), 3,204, 1,233, and 406 ceRNAs, respectively, engage in post-transcriptional intercommunication within tumor tissues, in contrast to their absence in corresponding healthy samples. We also found that 90 ceRNAs are shared by the three cancer types and that these ceRNAs participate in ceRNA interactions in tumor tissues compared to those in normal tissues. Among the 90 ceRNAs that directly interact with miRNAs, we uncovered a core network of 165 miRNAs and 63 ceRNAs that should be considered in RNA-targeted and RNA-mediated approaches in future studies and could be used in these three aggressive cancer types. More specifically, in this core interaction network, ceRNAs such as GALNT7, KLF9, and DAB2 and miRNAs like miR-106a/b-5p, miR-20a-5p, and miR-519d-3p may have potential as common targets in the three critical cancers. In contrast to conventional methods that construct ceRNA networks using differentially expressed genes compared to normal tissues, our proposed approach identifies ceRNA players by considering their context within the ceRNA:miRNA interactions. Our results have the potential to reveal distinct and common ceRNA interactions in cancer types and to pinpoint critical RNAs, thereby paving the way for RNA-based strategies in the battle against cancer.

The role of ubiquitination and deubiquitination in PI3K/AKT/mTOR pathway: A potential target for cancer therapy

The PI3K/AKT/mTOR pathway controls key cellular processes, including proliferation and tumor progression, and abnormally high activation of this pathway is a hallmark in human cancers. The post-translational modification, such as Ubiquitination and deubiquitination, fine-tuning the protein level and the activity of members in this pathway play a pivotal role in maintaining normal physiological process. Emerging evidence show that the unbalanced ubiquitination/deubiquitination modification leads to human diseases via PI3K/AKT/mTOR pathway. Therefore, a comprehensive understanding of the ubiquitination/deubiquitination regulation of PI3K/AKT/mTOR pathway may be helpful to uncover the underlying mechanism and improve the potential treatment of cancer via targeting this pathway. Herein, we summarize the latest research progress of ubiquitination and deubiquitination of PI3K/AKT/mTOR pathway, systematically discuss the associated crosstalk between them, as well as focus the clinical transformation via targeting ubiquitination process.

A Genome-Wide Association Study of Small Cell Lung Cancer

INTRODUCTION

Small cell lung cancer (SCLC) comprises 10-15% of all lung cancer cases and is the most aggressive histological type. Survival is poor and the molecular landscape of this disease is extraordinarily complex. The objective of this paper was to perform a Genome-Wide Association Study (GWAS) of this disease using a case-control study specifically designed for small cell lung cancer (SCLC).

METHODS

Incident cases were consecutively recruited from 8 hospitals from different regions of Spain. Controls were recruited from the same hospitals using a frequency sampling based on age and sex distribution of cases. Biological samples were obtained along with detailed information on cases and controls lifestyle, including tobacco and radon exposure.

RESULTS

We included 271 SCLC cases and 557 controls. We found evidence (p-values<10-5) of an association in the complete dataset for several loci, while MAP4 showed a significant association in the gene-based analysis. Pathway analysis suggested that ATR, ATRIP, MCM4, MCM5, ORC4, RPA3 and CDC25A genes have a role on the onset of SCLC.

CONCLUSION

This study provides biological evidence for pathways related to SCLC, offering novel loci for further research.

The roles of protein ubiquitination in tumorigenesis and targeted drug discovery in lung cancer

The malignant lung cancer has a high morbidity rate and very poor 5-year survival rate. About 80% - 90% of protein degradation in human cells is occurred through the ubiquitination enzyme pathway. Ubiquitin ligase (E3) with high specificity plays a crucial role in the ubiquitination process of the target protein, which usually occurs at a lysine residue in a substrate protein. Different ubiquitination forms have different effects on the target proteins. Multiple short chains of ubiquitination residues modify substrate proteins, which are favorable signals for protein degradation. The dynamic balance adapted to physiological needs between ubiquitination and deubiquitination of intracellular proteins is beneficial to the health of the organism. Ubiquitination of proteins has an impact on many biological pathways, and imbalances in these pathways lead to diseases including lung cancer. Ubiquitination of tumor suppressor protein factors or deubiquitination of tumor carcinogen protein factors often lead to the progression of lung cancer. Ubiquitin proteasome system (UPS) is a treasure house for research and development of new cancer drugs for lung cancer, especially targeting proteasome and E3s. The ubiquitination and degradation of oncogene proteins with precise targeting may provide a bright prospect for drug development in lung cancer; Especially proteolytic targeted chimerism (PROTAC)-induced protein degradation technology will offer a new strategy in the discovery and development of new drugs for lung cancer.

Development of Clioquinol Platinum(IV) Conjugates as Autophagy-Targeted Antimetastatic Agents

A series of autophagy-targeted antimetastatic clioquinol (CLQ) platinum(IV) conjugates were designed and prepared by incorporating an autophagy activator CLQ into the platinum(IV) system. Complex 5 with the cisplatin core bearing dual CLQ ligands with potent antitumor properties was screened out as a candidate. More importantly, it displayed potent antimetastatic properties both in vitro and in vivo as expected. Mechanism investigation manifested that complex 5 induced serious DNA damage to increase γ-H2AX and P53 expression and caused mitochondria-mediated apoptosis through the Bcl-2/Bax/caspase3 pathway. Then, it promoted prodeath autophagy by suppressing PI3K/AKT/mTOR signaling and activating the HIF-1α/Beclin1 pathway. The T-cell immunity was elevated by restraining the PD-L1 expression and subsequently increasing CD3⁺ and CD8⁺ T cells. Ultimately, metastasis of tumor cells was suppressed by the synergistic effects of DNA damage, autophagy promotion, and immune activation aroused by CLQ platinum(IV) complexes. Key proteins VEGFA, MMP-9, and CD34 tightly associated with angiogenesis and metastasis were downregulated.

KLHL21/CYLD signaling confers aggressiveness in bladder cancer through inactivating NF-κB signaling

Bladder carcinoma (BC) is one of the most commonly diagnosed malignant cancers worldwide. Kelch-like protein 21 (KLHL21) has been shown to be involved in a number of human tumors. The study aimed to investigate the effects and mechanism of KLHL21 on BC progression. We found that KLHL21 expression was significantly decreased in human BC tissues and cell lines compared with the paired normal samples, and patients with lower KLHL21 expression exhibited poorer overall survival. In vitro studies then showed that KLHL21 over-expression significantly reduced the proliferation, migration and invasion in BC cells, while KLHL21 knockdown markedly accelerated the proliferative, migratory and invasive properties of BC cells. Animal studies confirmed that KLHL21 exhibited anti-tumor function in the xenograft mouse models, as indicated by the reduced tumor growth rates, and mice with KLHL21 knockdown showed the opposite tumor growth profile. Additionally, we found that KLHL21 negatively mediated the nuclear factor-κB (NF-κB) signaling activation, as well as its down-streaming molecules involved in the biological regulation of cell survival, death and migratory processes. Mechanistically, cylindromatosis (CYLD) expression levels were significantly up-regulated in BC cells over-expressing KLHL21, but were down-regulated upon KLHL21 knockdown. We further uncovered that KLHL21 directly interacted with CYLD in BC cells. Of note, we found that KLHL21 mainly in cytoplasm could restrain CYLD degradation by prohibiting its ubiquitination in BC cells. More importantly, our in vitro experiments displayed that KLHL21-inhibited progression and NF-κB/p65 activation in BC cells were completely abolished by CYLD deletion, revealing that CYLD expression was required for KLHL21 to perform its anti-tumor function in BC. Collectively, all these findings uncovered that KLHL21/CYLD axis may be a promising therapeutic target for BC treatment.

Upregulation of KLHL17 promotes the proliferation and migration of non-small cell lung cancer by activating the Ras/MAPK signaling pathway

Analysis of the Gene Expression Profiling Interactive Analysis (GEPIA) database revealed that Kelch-like 17 (KLHL17) is overexpressed in non-small cell lung cancer (NSCLC) including adenocarcinoma (ADC) and squamous cell carcinoma (SCC). We therefore explored the role of KLHL17 in the development and progression of NSCLC. Immunohistochemistry and western blotting showed that KLHL17 expression was significantly higher in the tumor tissues from 173 patients with NSCLC, compared with the corresponding non-neoplastic tissue. In addition, upregulated KLHL17 expression was positively correlated with tumor size, lymph node metastasis and tumor node metastasis (TNM) stage, and affected the overall survival (OS) of patients with NSCLC. Consistent with clinical samples, in vitro studies demonstrated that KLHL17 expression was higher in various cell lines of NSCLC (A549, H1299, H460 and SK cells) as compared to normal human bronchial epithelial cells (HBE cells). Overexpression of KLHL17 in the cell lines of NSCLC with KLHL17-Flag plasmid promoted the proliferation and migration of tumor cells, which was associated with elevated activation of Rat sarcoma/Mitogen-activated protein kinases (Ras/MAPK) signaling and increased expression of cyclin D1, cyclin D-dependent kinases 4 (CDK4), matrix metalloproteinase 2 (MMP2) and Ras homolog gene family member A (RhoA). In contrast, knockdown of KLHL17 in the cell lines of NSCLC using KLHL17 small interfering RNA suppressed the proliferation and migration of tumor cells, in association with reduced activation of Ras/MAPK signaling and decreased expression of cyclin D1, CDK4, MMP2 and RhoA. Moreover, treatment of tumor cells with Ras inhibitor salirasib prevented KLHL17-induced Ras/MAPK activity as well as tumor proliferation and migration. These results suggest that upregulated KLHL17 in NSCLC promotes the proliferation and migration of tumor by activating Ras/MAPK signaling pathway. Therefore, KLHL17 may be a novel therapeutic target for the treatment of NSCLC.

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.

CUL3/SPOP complex prevents immune escape and enhances chemotherapy sensitivity of ovarian cancer cells through degradation of PD-L1 protein

BACKGROUND

Cancer immune escape is a main obstacle in designing effective anticancer therapeutic approaches. Our work was aimed to explore the function of cullin 3 (CUL3) in ovarian cancer cell immune escape and chemosensitivity.

METHOD

Gain and loss of function assays were conducted to investigate the interactions among CUL3, speckle type POZ protein (SPOP) and programmed death ligand-1 (PD-L1) as well as their effects on ovarian cell malignant phenotypes and chemosensitivity. A mouse model of xenografted ovarian cells was further established for in vivo substantiation.

RESULT

Poorly-expressed CUL3 and SPOP were found in ovarian cancer. Overexpression of CUL3 reduced malignant features as well as immune escape of ovarian cancer cells but enhanced chemosensitivity. Functionally, CUL3 degraded PD-L1 protein by forming complex with SPOP. Overexpression of CUL3 inhibited tumor formation and enhanced chemosensitivity of ovarian cancer cells in mice by degrading PD-L1 protein.

CONCLUSION

All in all, CUL3/SPOP formed a complex to promote PD-L1 degradation to inhibit ovarian cancer cell immune escape and increase chemosensitivity, offering a therapeutic target for ovarian cancer treatment.

Improvement of the anticancer efficacy of PD-1/PD-L1 blockade via combination therapy and PD-L1 regulation

Immune checkpoint molecules are promising anticancer targets, among which therapeutic antibodies targeting the PD-1/PD-L1 pathway have been widely applied to cancer treatment in clinical practice and have great potential. However, this treatment is greatly limited by its low response rates in certain cancers, lack of known biomarkers, immune-related toxicity, innate and acquired drug resistance, etc. Overcoming these limitations would significantly expand the anticancer applications of PD-1/PD-L1 blockade and improve the response rate and survival time of cancer patients. In the present review, we first illustrate the biological mechanisms of the PD-1/PD-L1 immune checkpoints and their role in the healthy immune system as well as in the tumor microenvironment (TME). The PD-1/PD-L1 pathway inhibits the anticancer effect of T cells in the TME, which in turn regulates the expression levels of PD-1 and PD-L1 through multiple mechanisms. Several strategies have been proposed to solve the limitations of anti-PD-1/PD-L1 treatment, including combination therapy with other standard treatments, such as chemotherapy, radiotherapy, targeted therapy, anti-angiogenic therapy, other immunotherapies and even diet control. Downregulation of PD-L1 expression in the TME via pharmacological or gene regulation methods improves the efficacy of anti-PD-1/PD-L1 treatment. Surprisingly, recent preclinical studies have shown that upregulation of PD-L1 in the TME also improves the response and efficacy of immune checkpoint blockade. Immunotherapy is a promising anticancer strategy that provides novel insight into clinical applications. This review aims to guide the development of more effective and less toxic anti-PD-1/PD-L1 immunotherapies.

KLHL38 involvement in non-small cell lung cancer progression via activation of the Akt signaling pathway

Lung cancer is the leading cause of cancer-related death worldwide. KLHL38 has been reported to be upregulated during diapause but downregulated after androgen treatment during the reversal of androgen-dependent skeletal muscle atrophy. This study aimed to clarify the role of KLHL38 in non-small cell lung cancer (NSCLC). KLHL38 expression was evaluated in tumor and adjacent normal tissues from 241 patients with NSCLC using immunohistochemistry and real-time PCR, and its association with clinicopathological parameters was analyzed. KLHL38 levels positively correlated with tumor size, lymph node metastasis, and pathological tumor-node-metastasis stage (all P < 0.001). In NSCLC cell lines, KLHL38 overexpression promoted PTEN ubiquitination, thereby activating Akt signaling. It also promoted cell proliferation, migration, and invasion by upregulating the expression of genes encoding cyclin D1, cyclin B, c-myc, RhoA, and MMP9, while downregulating the expression of p21 and E-cadherin. In vivo experiments in nude mice further confirmed that KLHL38 promotes NSCLC progression through Akt signaling pathway activation. Together, these results indicate that KLHL38 is a valuable candidate prognostic biomarker and potential therapeutic target for NSCLC.