GRP75 modulates oncogenic Dbl-driven endocytosis derailed via the CHIP-mediated ubiquitin degradation pathway

BI1 Activates Autophagy and Mediates TDP43 to Regulate ALS Pathogenesis

Amyotrophic lateral sclerosis (ALS) is the most prevalent motor neuron disease in adults. Currently, there are no known drugs or clinical approaches that have demonstrated efficacy in treating ALS. Mitochondrial function and autophagy have been identified as crucial mechanisms in the development of ALS. While Bax inhibitor 1 (BI1) has been implicated in neurodegenerative diseases, its exact mechanism remains unknown. This study investigates the therapeutic impact of BI1 overexpression on ALS both in vivo and in vitro, revealing its ability to mitigate SOD1G93A-induced apoptosis, nuclear damage, mitochondrial dysfunction, and axonal degeneration of motor neurons. At the same time, BI1 prolongs onset time and lifespan of ALS mice, improves motor function, and alleviates neuronal damage, muscle damage, neuromuscular junction damage among other aspects. The findings indicate that BI1 can inhibit pathological TDP43 morphology and initially stimulate autophagy through interaction with TDP43. This study establishes a solid theoretical foundation for understanding the regulation of autophagy by BI1 and TDP43 while shedding light on the pathogenesis of ALS through their interaction - offering new concepts and targets for clinical implementation and drug development.

Vesicle-mediated transport-related genes predict the prognosis and immune microenvironment in hepatocellular carcinoma

Background: Liver hepatocellular carcinoma (LIHC) is one of the leading causes of cancer-related death. The prognostic outcomes of advanced LIHC patients are poor. Hence, reliable prognostic biomarkers for LIHC are urgently needed. Methods: Data for vesicle-mediated transport-related genes (VMTRGs) were profiled from 338 LIHC and 50 normal tissue samples downloaded from The Cancer Genome Atlas (TCGA). Univariate Cox regression and Least Absolute Shrinkage and Selection Operator (LASSO) regression analyses were performed to construct and optimize the prognostic risk model. Five GEO datasets were used to validate the risk model. The roles of the differentially expressed genes (DEGs) were investigated via Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) enrichment analyses. Differences in immune cell infiltration between the high- and low-risk groups were evaluated using five algorithms. The "pRRophetic" was used to calculate the anticancer drug sensitivity of the two groups. Transwell and wound healing assays were performed to assess the role of GDP dissociation inhibitor 2 (GDI2) on LIHC cells. Results: A total of 166 prognosis-associated VMTRGs were identified, and VMTRGs-based risk model was constructed for the prognosis of LIHC patients. Four VMTRGs (GDI2, DYNC1LI1, KIF2C, and RAB32) constitute the principal components of the risk model associated with the clinical outcomes of LIHC. Tumor stage and risk score were extracted as the main prognostic indicators for LIHC patients. The VMTRGs-based risk model was significantly associated with immune responses and high expression of immune checkpoint molecules. High-risk patients were less sensitive to most chemotherapeutic drugs but benefited from immunotherapies. In vitro cellular assays revealed that GDI2 significantly promoted the growth and migration of LIHC cells. Conclusions: A VMTRGs-based risk model was constructed to predict the prognosis of LIHC patients effectively. This risk model was closely associated with the immune infiltration microenvironment. The four key VMTRGs are powerful prognostic biomarkers and therapeutic targets for LIHC.

Suicide gene delivery by morphology-adaptable enantiomeric peptide assemblies for combined ovarian cancer therapy

Suicide gene therapy is a promising therapeutic model for ovarian cancer (OC), while suffering from poor gene delivery and limited therapeutic efficacy. To address this concern, here we reported the GSH-responsive morphology-transformable enantiomeric peptide assemblies as delivering vehicles for suicide genes and co-delivery of paclitaxel (PTX). Connecting a lipid-like amphiphile and a hydrophilic arginine segment through disulfide bonds led to the enantiomeric peptides. The enantiomeric peptide assemblies are able to simultaneously uptake plasmid DNA (pDNA) and PTX based on electrostatic and hydrophobic interactions. The resulting co-assemblies underwent GSH-responsive disulfide cleavage and thereby promoting their assembly from nanoparticles to nanofibers, leading to the co-release of pDNA and PTX. Cellular and animal studies confirmed the co-delivery of pDNA and PTX into OC cells and the cell apoptosis by the enantiomeric peptides. In addition, in vitro and in vivo experiments supported the advanced uptake and cytotoxicity for L-type peptide vehicles by OC cells, and their great potential for OC-imaging, growth-inhibition and apoptosis-induction compared to D-counterpart. Our results demonstrate that the GSH-responsive morphology-transformable chiral peptide assemblies accurately and simultaneously release suicide genes and chemodrugs at tumor sites, thus providing a new strategy for the development of delivering vehicles for suicide gene and establishment of new therapeutic models for ovarian cancer. STATEMENT OF SIGNIFICANCE: Appropriate delivery carriers are essential for the clinical translation of cancer gene therapy, including the emerging suicide gene therapy. By combining the advantages of morphological transformable vehicles with the chirality peptides towards their bioactivity, we developed the GSH-responsive morphology-transformable enantiomeric peptide assemblies as delivering vehicles for suicide genes and co-delivery of paclitaxel. The GSH-responsive assembly of the enantiomeric peptides allows for precise release of plasmid DNA and paclitaxel in cancer cells, and promotes the formation of nanofibrils that facilitate gene entering nuclei for transfection. The enantiomeric peptide-based vehicles show the chirality-dependent capability for inducing cell apoptosis and inhibiting tumor growth. Our findings demonstrate a new strategy for developing therapeutic models for ovarian cancer.

GRP75-driven, cell-cycle-dependent macropinocytosis of Tat/pDNA-Ca2+ nanoparticles underlies distinct gene therapy effect in ovarian cancer

Practice of tumor-targeted suicide gene therapy is hampered by unsafe and low efficient delivery of plasmid DNA (pDNA). Using HIV-Tat-derived peptide (Tat) to non-covalently form Tat/pDNA complexes advances the delivery performance. However, this innovative approach is still limited by intracellular delivery efficiency and cell-cycle status. In this study, Tat/pDNA complexes were further condensed into smaller, nontoxic nanoparticles by Ca²⁺ addition. Formulated Tat/pDNA-Ca²⁺ nanoparticles mainly use macropinocytosis for intercellular delivery, and their macropinocytic uptake was persisted in mitosis (M-) phase and highly activated in DNA synthesis (S-) phase of cell-cycle. Over-expression or phosphorylation of a mitochondrial chaperone, 75-kDa glucose-regulated protein (GRP75), promoted monopolar spindle kinase 1 (MPS1)-controlled centrosome duplication and cell-cycle progress, but also driven cell-cycle-dependent macropinocytosis of Tat/pDNA-Ca²⁺ nanoparticles. Further in vivo molecular imaging based on DF (Fluc-eGFP)-TF (RFP-Rluc-HSV-ttk) system showed that Tat/pDNA-Ca²⁺ nanoparticles exhibited highly suicide gene therapy efficiency in mouse model xenografted with human ovarian cancer. Furthermore, arresting cell-cycle at S-phase markedly enhanced delivery performance of Tat/pDNA-Ca²⁺ nanoparticles, whereas targeting GRP75 reduced their macropinocytic delivery. More importantly, in vivo targeting GRP75 combined with cell-cycle or macropinocytosis inhibitors exhibited distinct suicide gene therapy efficiency. In summary, our data highlight that mitochondrial chaperone GRP75 moonlights as a biphasic driver underlying cell-cycle-dependent macropinocytosis of Tat/pDNA-Ca²⁺ nanoparticles in ovarian cancer.

Insights Into the Role of Mortalin in Alzheimer’s Disease, Parkinson’s Disease, and HIV-1-Associated Neurocognitive Disorders

Mortalin is a chaperone protein that regulates physiological functions of cells. Its multifactorial role allows cells to survive pathological conditions. Pharmacological, chemical, and siRNA-mediated downregulation of mortalin increases oxidative stress, mitochondrial dysfunction leading to unregulated inflammation. In addition to its well-characterized function in controlling oxidative stress, mitochondrial health, and maintaining physiological balance, recent evidence from human brain autopsies and cell culture–based studies suggests a critical role of mortalin in attenuating the damage seen in several neurodegenerative diseases. Overexpression of mortalin provides an important line of defense against accumulated proteins, inflammation, and neuronal loss, a key characteristic feature observed in neurodegeneration. Neurodegenerative diseases are a group of progressive disorders, sharing pathological features in Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, and HIV-associated neurocognitive disorder. Aggregation of insoluble amyloid beta-proteins and neurofibrillary tangles in Alzheimer’s disease are among the leading cause of neuropathology in the brain. Parkinson’s disease is characterized by the degeneration of dopamine neurons in substantia nigra pars compacta. A substantial synaptic loss leading to cognitive decline is the hallmark of HIV-associated neurocognitive disorder (HAND). Brain autopsies and cell culture studies showed reduced expression of mortalin in Alzheimer’s, Parkinson’s, and HAND cases and deciphered the important role of mortalin in brain cells. Here, we discuss mortalin and its regulation and describe how neurotoxic conditions alter the expression of mortalin and modulate its functions. In addition, we also review the neuroprotective role of mortalin under neuropathological conditions. This knowledge showcases the importance of mortalin in diverse brain functions and offers new opportunities for the development of therapeutic targets that can modulate the expression of mortalin using chemical compounds.

Wnt/β-catenin signaling and p68 conjointly regulate CHIP in colorectal carcinoma

Emerging evidences suggest abundant expression of Carboxy terminus of Hsc70 Interacting Protein or CHIP (alias STIP1 Homology and U-box Containing Protein 1 or STUB1) in colorectal carcinoma, but the mechanistic detail of this augmented expression pattern is unclear. The signature driver of canonical Wnt pathway, β-catenin, and its co-activator RNA helicase p68, are also overexpressed in colorectal carcinoma. In this study, we describe a novel mechanism of Wnt/β-catenin and p68 mediated transcriptional activation of CHIP gene leading to enhanced proliferation of colorectal carcinoma cells. Bioinformatic analyses reconfirmed an elevated CHIP expression level in colorectal carcinoma datasets. Wnt3A treatment and pharmacological activation of canonical Wnt signaling pathway resulted in increased nuclear translocation of β-catenin, augmenting CHIP expression. Likewise, immunoblotting and Real time PCR following overexpression and knockdown of β-catenin and p68 demonstrated upregulated and downregulated CHIP expression, respectively, at both mRNA and protein levels. p68 along with β-catenin were found to occupy Transcription Factor 4 (TCF4) binding sites on endogenous CHIP promoter and regulate its transcription. After cloning CHIP promoter, the increased and decreased promoter activities of CHIP induced by overexpression and knockdown of either β-catenin or p68 further confirmed transcriptional regulation of CHIP gene by Wnt/β-catenin signaling cascade. Finally, enhanced cellular propagation and migration of colorectal carcinoma cells induced by 'Wnt/β-catenin-p68-CHIP' axis established the significance of this pathway in oncogenesis. To the best of our knowledge, this is the first report elucidating the mechanistic details of transcriptional regulation of CHIP (STUB1) gene expression.

DAB2IP suppresses tumor malignancy by inhibiting GRP75-driven p53 ubiquitination in colon cancer

Increasing evidence has shown that DAB2IP acts as a tumor suppressor and plays an inhibitory role in many signals associated with tumorigenesis. However, the underlying mechanism of this function remains unclear. Our study shows that DAB2IP was positively associated with a good prognosis in patients with colorectal cancer and wild-type p53 expression. An in vitro assay showed that DAB2IP elicited potent tumor-suppressive effects by inhibiting cell invasiveness and colony formation and promoting cell apoptosis in wild-type p53 colon cancer cells. In addition, DAB2IP improved the stability of wild-type p53 by inhibiting its degradation in a ubiquitin-proteasome-dependent manner. Using mass spectrometry profiling, we revealed that DAB2IP and p53 interacted with the ubiquitin ligase-related protein GRP75. Mechanistically, DAB2IP is competitively bound to GRP75, thus reducing GRP75-driven p53 ubiquitination and degradation. Moreover, the Ras-GAP domain was required for the DAB2IP-GRP75 interaction and DAB2IP-mediated p53 ubiquitination. Finally, animal experiments revealed that DAB2IP inhibited tumor progression in vivo. In conclusion, our study presents a novel function of DAB2IP in GRP75-driven wild-type p53 degradation, providing new insight into DAB2IP-induced tumor suppression and a novel molecular interpretation of the p53 pathway.

Arf6-mediated macropinocytosis-enhanced suicide gene therapy of C16TAB-condensed Tat/pDNA nanoparticles in ovarian cancer

The use of cell-penetrating peptides (CPPs), typically HIV-Tat, to deliver therapeutic genes for cancer treatment is hampered by the inefficient delivery and complicated uptake route of plasmid DNA (pDNA). On the one hand, surface charges, particle size and shape essentially contribute to the endocytosis pathway of Tat/pDNA nanocomplexes, and on the other hand, endogenous cellular factors dominantly determine their intracellular trafficking fate and biological outcome. Recent advances in surfactant-modified nanomaterial and dual molecular imaging technology have offered new opportunities for suicide gene therapy. In this study, we employed the cationic surfactant C16TAB to further condense Tat/pDNA nanocomplexes for improving their delivery efficiency and tested the therapeutic effect of Tat/pDNA/C16TAB (T-P-C) nanoparticles carrying the GCV-converted HSV-ttk suicide gene for ovarian cancer. The cellular endocytosis pathway and underlying signal mechanism of T-P-C nanoparticles were further determined. The obtained T-P-C nanoparticles exhibited a small size, positive surface charge, irregular granular shape and high pDNA encapsulation efficiency. The in vitro experiments showed that T-P-C nanoparticles mainly used the macropinocytosis pathway for uptake in ovarian cancer cells. Their internalization and payload gene expression were controlled by the Arf6 GTPase-dependent, Rab GTPase-activated signal axis. Further in vivo molecular imaging based on DF (Fluc-eGFP)-TF (RFP-Rluc-HSV-ttk) system showed that T-P-C nanoparticles significantly increased the targeted delivery and suicide gene therapy in a mouse model xenografted with human ovarian cancer. More importantly, Arf6-mediated macropinocytosis remarkably enhanced the delivery efficiency and suicide gene therapy effect of T-P-C nanoparticles. Therefore, these C16TAB-condensed Tat/pDNA nanoparticles combined with the dual molecular imaging strategy provides a novel intracellular delivery platform for high-efficient, precise suicide gene therapy of ovarian cancer.

Chaperone-assisted E3 ligase CHIP: A double agent in cancer

The carboxy-terminus of Hsp70-interacting protein (CHIP) is a ubiquitin ligase and co-chaperone belonging to Ubox family that plays a crucial role in the maintenance of cellular homeostasis by switching the equilibrium of the folding-refolding mechanism towards the proteasomal or lysosomal degradation pathway. It links molecular chaperones viz. HSC70, HSP70 and HSP90 with ubiquitin proteasome system (UPS), acting as a quality control system. CHIP contains charged domain in between N-terminal tetratricopeptide repeat (TPR) and C-terminal Ubox domain. TPR domain interacts with the aberrant client proteins via chaperones while Ubox domain facilitates the ubiquitin transfer to the client proteins for ubiquitination. Thus, CHIP is a classic molecule that executes ubiquitination for degradation of client proteins. Further, CHIP has been found to be indulged in cellular differentiation, proliferation, metastasis and tumorigenesis. Additionally, CHIP can play its dual role as a tumor suppressor as well as an oncogene in numerous malignancies, thus acting as a double agent. Here, in this review, we have reported almost all substrates of CHIP established till date and classified them according to the hallmarks of cancer. In addition, we discussed about its architectural alignment, tissue specific expression, sub-cellular localization, folding-refolding mechanisms of client proteins, E4 ligase activity, normal physiological roles, as well as involvement in various diseases and tumor biology. Further, we aim to discuss its importance in HSP90 inhibitors mediated cancer therapy. Thus, this report concludes that CHIP may be a promising and worthy drug target towards pharmaceutical industry for drug development.

Blocking MCT4 SUMOylation inhibits the growth of breast cancer cells

Monocarboxylate transporter 4 (MCT4) is highly expressed in various types of solid neoplasms including breast cancer (BC); however, the pro-tumor functions underlying its increased expression have not been explained. Here, we examined the roles of posttranslational modifications to MCT4 in BC, particularly SUMOylation. Our findings revealed that SUMOylation of MCT4 inhibited its degradation and stabilized MCT4 protein levels, while ubiquitination facilitated MCT4 degradation. The E3 ubiquitin ligases β-TRCP and FBW7 interacted with MCT4 at the DSG-box and TPETS sequences, respectively, and Lys448 (K448) of MCT4 could be modified by SUMO chains. Our key finding was that K448 was crucial for MCT4 SUMOylation. Moreover, mutations of K448 abolished MCT4 expression, delaying the growth of BC. This study suggested that SUMOylation of K448 increased MCT4 levels, and mutations of K448 in MCT4 could have therapeutic significance in BC.

Biomarkers of tumor invasiveness in proteomics (Review)

Over the past two decades, quantitative proteomics has emerged as an important tool for deciphering the complex molecular events involved in cancers. The number of references involving studies on the cancer metastatic process has doubled since 2010, while the last 5 years have seen the development of novel technologies combining deep proteome coverage capabilities with quantitative consistency and accuracy. To highlight key findings within this huge amount of information, the present review identified a list of tumor invasive biomarkers based on both the literature and data collected on a biocollection of experimental cell lines, tumor models of increasing invasiveness and tumor samples from patients with colorectal or breast cancer. Crossing these different data sources led to 76 proteins of interest out of 1,245 mentioned in the literature. Information on these proteins can potentially be translated into clinical prospects, since they represent potential targets for the development and evaluation of innovative therapies, alone or in combination. Herein, a systematical review of the biology of each of these proteins, including their specific subcellular/extracellular or multiple localizations is presented. Finally, as an important advantage of quantitative proteomics is the ability to provide data on all these molecules simultaneously in cell pellets, body fluids or paraffin‑embedded sections of tumors/invaded tissues, the significance of some of their interconnections is discussed.

Arf6-driven endocytic recycling of CD147 determines HCC malignant phenotypes

BACKGROUND

Adhesion molecules distributed on the cell-surface depends upon their dynamic trafficking that plays an important role during cancer progression. ADP-ribosylation factor 6 (Arf6) is a master regulator of membrane trafficking. CD147, a tumor-related adhesive protein, can promote the invasion of liver cancer. However, the role of Arf6 in CD147 trafficking and its contribution to liver cancer progression remain unclear.

METHODS

Stable liver cancer cell lines with Arf6 silencing and over-expression were established. Confocal imaging, flow cytometry, biotinylation and endomembrane isolation were used to detect CD147 uptake and recycling. GST-pull down, gelatin zymography, immunofluorescence, cell adhesion, aggregation and tight junction formation, Transwell migration, and invasion assays were used to examine the cellular phenotypes. GEPIA bioinformatics, patient's specimens and electronic records collection, and immunohistochemistry were performed to obtain the clinical relevance for Arf6-CD147 signaling.

RESULTS

We found that the endocytic recycling of CD147 in liver cancer cells was controlled by Arf6 through concurrent Rab5 and Rab22 activation. Disruption of Arf6-mediated CD147 trafficking reduced the cell-matrix and cell-cell adhesion, weakened cell aggregation and junction stability, attenuated MMPs secretion and cytoskeleton reorganization, impaired HGF-stimulated Rac1 activation, and markedly decreased the migration and invasion of liver cancer cells. Moreover, high-expression of the Arf6-CD147 signaling components in HCC (hepatocellular carcinoma) was closely correlated with poor clinical outcome of patients.

CONCLUSIONS

Our results revealed that Arf6-mediated CD147 endocytic recycling is required for the malignant phenotypes of liver cancer. The Arf6-driven signaling machinery provides excellent biomarkers or therapeutic targets for the prevention of liver cancer.

YIPF2 is a novel Rab-GDF that enhances HCC malignant phenotypes by facilitating CD147 endocytic recycle

An increased surface level of CIE (clathrin-independent endocytosis) proteins is a new feature of malignant neoplasms. CD147 is a CIE glycoprotein highly up-regulated in hepatocellular carcinoma (HCC). The ability to sort out the early endosome and directly target the recycling pathway confers on CD147 a prolonged surface half-life. However, current knowledge on CD147 trafficking to and from the cell-surface is limited. In this study, an MSP (membrane and secreted protein)-cDNA library was screened against EpoR/LR-F3/CD147EP-expressed cells by MAPPIT (mammalian protein–protein interaction trap). CD147 co-expressing with the new binder was investigated by GEPIA (gene expression profiling interactive analysis). The endocytosis, ER-Golgi trafficking and recycling of CD147 were measured by confocal imaging, flow cytometry, and biotin-labeled chase assays, respectively. Rab GTPase activation was checked by GST-RBD pull-down and MMP activity was measured by gelatin zymography. HCC malignant phenotypes were determined by cell adhesion, proliferation, migration, Transwell motility, and invasion assays. An ER-Golgi-resident transmembrane protein YIPF2 was identified as an intracellular binder to CD147. YIPF2 correlated and co-expressed with CD147, which is a survival predictor for HCC patients. YIPF2 is critical for CD147 glycosylation and trafficking functions in HCC cells. YIPF2 acts as a Rab-GDF (GDI-displacement factor) regulating three independent trafficking steps. First, YIPF2 recruits and activates Rab5 and Rab22a GTPases to the endomembrane structures. Second, YIPF2 modulates the endocytic recycling of CD147 through distinctive regulation on Rab5 and Rab22a. Third, YIPF2 mediates the mature processing of CD147 via the ER-Golgi trafficking route. Decreased YIPF2 expression induced a CD147 efficient delivery to the cell-surface, promoted MMP secretion, and enhanced the adhesion, motility, migration, and invasion behaviors of HCC cells. Thus, YIPF2 is a new trafficking determinant essential for CD147 glycosylation and transport. Our findings revealed a novel YIPF2-controlled ER-Golgi trafficking signature that promotes CD147-medated malignant phenotypes in HCC.