Potential role of tubulin tyrosine ligase-like enzymes in tumorigenesis and cancer cell resistance

VASH2 enhances KIF3C-mediated EGFR-endosomal recycling to promote aggression and chemoresistance of lung squamous cell carcinoma by increasing tubulin detyrosination

Lung squamous cell carcinoma (LUSC) is associated with high mortality and has few therapeutic options. Chemotherapy remains the main treatment for LUSC patients, but multi-drug resistance has become the dominant challenge in the failure of chemotherapy in various cancers. Therefore, the effective therapeutic strategy for LUSC patients is an urgent unmet need. Here, we found vasohibin-2 (VASH2) was a prognostic biomarker for LUSC patients, and VASH2 promoted the malignant biological behaviors of LUSC cells and chemoresistance by increasing the detyrosination of α-tubulin. The high level of detyrosinated-tubulin was negatively associated with patient prognosis. Blocking the tubulin carboxypeptidase (TCP) activity of VASH2 inhibited the xenograft tumor growth and improved the treatment efficacy of paclitaxel in vivo. Results revealed that VASH2-induced increase in tubulin detyrosination boosted the binding of kinesin family member 3C (KIF3C) to microtubules and enhanced KIF3C-dependent endosomal recycling of EGFR, leading to the prolonged activation of PI3K/Akt/mTOR signaling. This study demonstrated that VASH2 was not only a prognostic biomarker but also a promising therapeutic target in LUSC, which offers a novel insight that combination of chemotherapy and EpoY, a TCP inhibitor, may be a promising treatment strategy for LUSC patients.

Bioinformatic identification of differentially expressed genes regulated by DNA-methylation in glioblastoma

DNA methylation-driven differentially expressed genes (DEGs) play potentially important roles in glioblastoma (GBM). In the present study, we applied bioinformatic analyses to identify key methylation-regulated DEGs (MeDEGs) in glioblastoma and elucidate their functions. Gene expression and methylation profile data from glioblastoma samples along with clinical information were obtained from GEO and TCGA databases. A total of 65 genes were identified as MeDEGs from the aforementioned data. Subsequently, gene ontology and kyoto encyclopedia of genes and genomes enrichment analyses of these MeDEGs exhibited that MeDEGs were mostly enriched in several tumor-related terms such as "activation of cysteine-type endopeptidase activity involved in apoptotic process" and "phospholipid scrambling". Kaplan-Meier survival analysis demonstrated significant correlation of CASP1, CFH, and TTLL7 hyper-methylation with patient prognosis. Finally, CASP1 protein could indirectly interact with CFH protein, but interaction of TTLL7 protein with CASP1 or CFH protein was not evident. Based on gene set enrichment analysis, hyper-methylation of CASP1, CFH, and TTLL7 were found enriched in tumor-related KEGG terms, such as "RNA degradation", "apyruvate metabolism", and "nitrogen metabolism". Methylation levels of CASP1, CFH, and TTLL7 were addressed to negatively correlate with their mRNA levels in GBM cell lines. In sum, the present identification of MeDEGs associated with overall survival put forth potential molecular targets for translation towards improved diagnosis and treatment of GBM and specifically, methylation levels of CASP1, CFH, and TTLL7 genes could serve as key prognostic biomarkers in GBM.

Comprehensive analysis of lncRNA-associated ceRNA network reveals the novel potential of lncRNA, miRNA and mRNA biomarkers in human rectosigmoid junction cancer

Although accumulating evidence has confirmed the potential biological functions of long non-coding RNAs (lncRNAs) as competitive endogenous RNAs (ceRNAs) in colorectal tumorigenesis and progression, few studies have focused on rectosigmoid junction cancer. In the present study, a comprehensive analysis was conducted to explore lncRNA-mediated ceRNA implications and their potential value for prognosis. lncRNA, microRNA (miR/miRNA) and mRNA expression profiles were downloaded from The Cancer Genome Atlas database. Subsequently, a lncRNA-miRNA-mRNA regulatory network was constructed to evaluate the functions of these differentially expressed genes on overall survival (OS) for rectosigmoid junction cancer. As a result, a rectosigmoid junction cancer-specific ceRNA network was successfully constructed with 7 differentially expressed (DE)lncRNAs, 16 DEmiRNAs and 71 DEmRNAs. Among the network, one DElncRNA (small nucleolar RNA host gene 20) and three mRNAs (sodium- and chloride-dependent taurine transporter, fibroblast growth factor 13 and tubulin polyglutamylase TTLL7) were significantly associated with OS (P<0.05). Additionally, two lncRNAs (KCNQ1OT1 and MIR17HG) interacted with most of the DEmiRNAs. Notably, two top-ranked miRNAs (hsa-miR-374a-5p and hsa-miR-374b-5p) associated networks were identified to be markedly associated with the pathogenesis. Furthermore, four DEmRNAs (caveolin-1, MET, filamin-A and AKT3) were enriched in the Kyoto Encylopedia of Gene and Genomes pathway analysis, as well as being included in the ceRNA network. In summary, the present results revealed that a specific lncRNA-miRNA-mRNA network was associated with rectosigmoid junction cancer, providing several molecules that may be used as novel prognostic biomarkers and therapeutic targets.

Expression of ATP/GTP Binding Protein 1 Has Prognostic Value for the Clinical Outcomes in Non-Small Cell Lung Carcinoma

ATP/GTP binding protein 1 (AGTPBP1) encodes a crucial protein, cytosolic carboxypeptidase 1 (CCP1), which plays a role in modulating the polyglutamylation of tubulin and has been studied in degenerative diseases. However, the role of AGTPBP1 in malignancy has not been completely studied yet. In this study, we examined the role of AGTPBP1 in cancer progression, its association with patient survival, and related mechanisms in lung cancer, using the A549 cell line and lung cancer gene expression datasets. AGTPBP1 knockdown increased the proliferation, migration, sphere formation, and drug resistance of A549 cells. Lung cancer datasets revealed significantly lower mRNA and protein expression levels of AGTPBP1 in lung cancer tissues, as compared to those in normal tissues. Importantly, AGTPBP1 expression positively correlated with patient survival. Analysis of co-expressed genes revealed that AGTPBP1 expression positively correlated with immune infiltration in lung cancer. Our results conclusively suggested that AGTPBP1 expression was correlated with cancer progression and immune infiltration in lung cancer.

Cross-Linking of Thiolated Paclitaxel-Oligo(p-phenylene vinylene) Conjugates Aggregates inside Tumor Cells Leads to "Chemical Locks" That Increase Drug Efficacy

How to reduce the resistance of certain tumor cells to paclitaxel (PTX) and related taxoid anticancer drugs is a major challenge for improving cure rates. An oligo(p-phenylenevinylene) unit with thiol groups and a PTX unit (OPV-S-PTX), which enhances drug efficacy and reverses resistance is thus designed. The mechanism involves diffusion of OPV-S-PTX into the cell, where π-π interactions lead to aggregation. Cross-linking of the aggregates via oxidation of thiol groups is favored in tumor cells because of the higher reactive oxygen species (ROS) concentration. Cross-linked aggregates "chemically lock" the multichromophore particle for a more persistent effect. The IC₅₀ of OPV-S-PTX for tumor cell line A549 is reduced down to 0.33 × 10^-9 m from that observed for PTX itself (41 × 10^-9 m). Enhanced efficacy by OPV-S-PTX is proposed to proceed via acceleration of microtubule bundle formation. A549/T-inoculated xenograft mice experiments reveal suppression of tumor growth upon OPV-S-PTX treatment. Altogether, these results show that the internal cross-linking of OPV-S-PTX through ROS provides a means to discriminate between tumor and healthy cells and the formation of the chemically locked particles enhances drug efficacy and helps in reducing resistance.

Reduced cytosolic carboxypeptidase 6 (CCP6) level leads to accumulation of serum polyglutamylated DNAJC7 protein: A potential biomarker for renal cell carcinoma early detection

Renal cell carcinoma (RCC) is frequently diagnosed at advanced stages of disease, although early diagnosis has much favorable prognosis. This study assessed aberrant expression of cytosolic carboxypeptidase 6 (CCP6) leading to accumulation of serum polyglutamylated DNAJC7 as a biomarker for early RCC detection. A total of 835 RCCs, 143 chronic nephritis, 170 kidney stones and 415 health controls were collected for qRT-PCR, immunohistochemistry and Western blot analysis of CCP6 expression and mass spectrometry of DNAJC7 and polyglutamylated DNAJC7. The data showed that CCP6 expression was significantly decreased in 30 RCC tissues and that mass spectrometric and pull-down analysis identified DNAJC7 as a substrate of CCP6 and showed upregulated polyglutamylated-DNAJC7 (polyE-DNAJC7) in sera of RCC patients. The electrochemiluminescence immunoassay of large-scale serum samples from multi-institutes further confirmed the remarkable increase of polyE-DNAJC7 in 805 RCCs compared to that of 385 healthy controls (p < 0.001), 128 patients with chronic nephritis (p < 0.001), and 153 with kidney stone (p < 0.001). Serum level of DNAJC7-polyE protein was also associated with advanced RCC stage and grade in 805 patients. The data from the current study for the first time demonstrated increased serum polyglutamylated DNAJC7 as a potential biomarker for RCC early detection and association with advanced tumor stages and grade, which provides support of further polyglutamylation research in RCC.

Self-Catalyzed Assembly of Peptide Scaffolded Nanozyme as a Dynamic Biosensing System

In this work, a new strategy of biosensor design is developed based on the assembly of amyloid beta and its multiple interactions with other bioactive species. These interactions can enable amyloid beta peptide as a multifunctional sensing element, so the immobilization of sensing probe and the step-by-step modification of the sensing interface have all been dispensed with. Instead, the kinetics of the assembly of a peptide-based catalytic network serves to convert the quantity of analyte into amplified signal readout. The designed dynamic assembling and biosensing system has also been successfully applied in detecting the activity of polyglutamylation, an essential post translation modification controlling cell skeleton and cell cycle, in biological complex samples. Further studies reveal that the serum abundance of a polyglutamylase, tubulin tyrosine ligase-like protein 12, may show parallel with the degree of development of prostate cancer and the discrimination between early cancerous development and benign conditions. And the obtained result is more distinct than that based on PSA detection, the current gold standard. This study may also point to the prospective of extending this design strategy to broader range of biosensing applications in the future.

Emerging microtubule targets in glioma therapy

Major advances in the genomics and epigenomics of diffuse gliomas and glioblastoma to date have not been translated into effective therapy, necessitating pursuit of alternative treatment approaches for these therapeutically challenging tumors. Current knowledge of microtubules in cancer and the development of new microtubule-based treatment strategies for high-grade gliomas are the topic in this review article. Discussed are cellular, molecular, and pharmacologic aspects of the microtubule cytoskeleton underlying mitosis and interactions with other cellular partners involved in cell cycle progression, directional cell migration, and tumor invasion. Special focus is placed on (1) the aberrant overexpression of βIII-tubulin, a survival factor associated with hypoxic tumor microenvironment and dynamic instability of microtubules; (2) the ectopic overexpression of γ-tubulin, which in addition to its conventional role as a microtubule-nucleating protein has recently emerged as a transcription factor interacting with oncogenes and kinases; (3) the microtubule-severing ATPase spastin and its emerging role in cell motility of glioblastoma cells; and (4) the modulating role of posttranslational modifications of tubulin in the context of interaction of microtubules with motor proteins. Specific antineoplastic strategies discussed include downregulation of targeted molecules aimed at achieving a sensitization effect on currently used mainstay therapies. The potential role of new classes of tubulin-binding agents and ATPase inhibitors is also examined. Understanding the cellular and molecular mechanisms underpinning the distinct behaviors of microtubules in glioma tumorigenesis and drug resistance is key to the discovery of novel molecular targets that will fundamentally change the prognostic outlook of patients with diffuse high-grade gliomas.