Bioinformatics analysis of Rab GDP dissociation inhibitor beta and its expression in non-small cell lung cancer

Targeting GDP-Dissociation Inhibitor Beta (GDI2) with a Benzo[a]quinolizidine Library to Induce Paraptosis for Cancer Therapy

Inducing paraptosis, a nonapoptotic form of cell death, has great therapeutic potential in cancer therapy, especially for drug-resistant tumors. However, the specific molecular target(s) that trigger paraptosis have not yet been deciphered yet. Herein, by using activity-based protein profiling, we identified the GDP-dissociation inhibitor beta (GDI2) as a manipulable target for inducing paraptosis and uncovered benzo[a]quinolizidine BQZ-485 as a potent inhibitor of GDI2 through the interaction with Tyr245. Comprehensive target validation revealed that BQZ-485 disrupts the intrinsic GDI2-Rab1A interaction, thereby abolishing vesicular transport from the endoplasmic reticulum (ER) to the Golgi apparatus and initiating subsequent paraptosis events including ER dilation and fusion, ER stress, the unfolded protein response, and cytoplasmic vacuolization. Based on the structure of BQZ-485, we created a small benzo[a]quinolizidine library by click chemistry and discovered more potent GDI2 inhibitors using a NanoLuc-based screening platform. Leveraging the engagement of BQZ-485 with GDI2, we developed a selective GDI2 degrader. The optimized inhibitor (+)-37 and degrader 21 described in this study exhibited excellent in vivo antitumor activity in two GDI2-overexpressing pancreatic xenograft models, including an AsPc-1 solid tumor model and a transplanted human PDAC tumor model. Altogether, our findings provide a promising strategy for targeting GDI2 for paraptosis in the treatment of pancreatic cancers, and these lead compounds could be further optimized to be effective chemotherapeutics.

Identification of changed proteins by retinoic acid in cerebral ischemic damage: a proteomic study

Ischemic stroke is a severe neurodegenerative disease with a high mortality rate. Retinoic acid is a representative metabolite of vitamin A. It has many beneficial effects including anti-inflammatory, anti-apoptotic, and neuroprotective effects. The purpose of this study is to identify specific proteins that are regulated by retinoic acid in ischemic stroke. Middle cerebral artery occlusion (MCAO) was performed to induce focal cerebral ischemia. Retinoic acid (5 mg/kg) or vehicle was injected intraperitoneally into male rats for four days prior to MCAO operation. Neurobehavioral tests were performed 24 hr after MCAO and the cerebral cortex was collected for proteomic study. Retinoic acid alleviates neurobehavioral deficits and histopathological changes caused by MCAO. Furthermore, we identified various proteins that were altered by retinoic acid in MCAO damage. Among these identified proteins, adenosylhomocysteinase, isocitrate dehydrogenase [NAD+] subunit α, glycerol-3-phosphate dehydrogenase, Rab GDP dissociation inhibitor β, and apolipoprotein A1 were down-regulated in MCAO animals with vehicle treatment, whereas retinoic acid treatment alleviated these reductions. However, heat shock protein 60 was up-regulated in MCAO animals with vehicle, while retinoic acid treatment attenuated this increase. The changes in these expressions were confirmed by reverse transcription-PCR. These proteins regulate cell metabolism and mediate stress responses. Our results demonstrated that retinoic acid attenuates the neuronal damage by MCAO and regulates the various protein expressions that are involved in the survival of cells. Thus, we can suggest that retinoic acid exerts neuroprotective effects on focal cerebral ischemia by modulation of specific proteins.

Overexpression of GDP dissociation inhibitor 1 gene associates with the invasiveness and poor outcomes of colorectal cancer

GDP dissociation inhibitor (GDI) regulates the GDP/GTP exchange reaction of most Rab proteins by inhibiting GDP dissociation. This study evaluated the potential prognostic and predictive value of GDI1 in colorectal cancer (CRC). To address the prognostic power of GDI1, we performed individual and pooled survival analyses on six independent CRC microarray gene expression datasets. GDI1-enriched signatures were also analyzed. Kaplan-Meier and Cox proportional analyses were employed for survival analysis. An immunohistochemistry (IHC) analysis was performed to validate the clinical relevance and prognostic significance of the GDI1 protein level in CRC tissue samples. The results revealed that GDI1 mRNA level was significantly linked with the aggressiveness of CRC, which is compatible with gene set enrichment analysis. A meta-analysis and pooled analysis demonstrated that a higher mRNA GDI1 expression was dramatically correlated with a worse survival in a dose-dependent manner in CRC patients. Further IHC analysis validated that the protein expression of GDI1 in both cytoplasm and membrane also significantly impacted the outcome of CRC patients. In CRC patients with stage III, chemotherapy significantly reduced the relative risk of death in low-GDI1 subgroup (hazard ratio (HR) = 0.22; 95% confidence interval (95% CI) 0.09-0.56, p = 0.0003), but not in high-GDI1 subgroup (HR = 0.63; 95% CI 0.35-1.14, p = 0.1137). Therefore, both high mRNA and protein levels of GDI1 were significantly related to poor outcomes in CRC patients. GD11 may serve as a prognostic biomarker for CRC.

as a Candidate Gene for an Infection-Induced Acute Encephalopathy Characterized by a Cyst and Calcification of the Pons and Cerebellar Atrophy

Three siblings born to Turkish parents from the same village had normal brain development until acute neurological deterioration between 12 months and 8 years of age. Consequent loss of all acquired motor, social, and language functions following infections was associated with a pontine cyst, calcification, and cerebellar atrophy. Exome sequencing revealed a homozygous c.1297G&#x3e;A (p.Gly433Ser) alteration in <i>BEND4</i>, which was predicted to be deleterious in in silico analysis tools and segregated in multiple affected individuals in the family. <i>BEND4</i> has not been associated with any existing disease. Immunofluorescence microscopy analysis of wild-type and mutant BEND4 expressing Vero cells showed nuclear and cytoplasmic localization. Wild-type BEND4 displayed a network-like distribution, whereas mutant BEND4 showed a juxtanuclear distribution pattern. Differential proteome analysis of Vero cells expressing BEND4 revealed that mutant BEND4 expression caused selective increase in reticulocalbin-1 and endoplasmic reticulum resident protein-29. Both proteins are associated with the endoplasmic reticulum and are primarily involved in protein processing and folding pathways. Any defect or stress in protein folding creates stress on cells and may cause chronic damage. This is the first study showing that pathogenic <i>BEND4</i> variants may lead to an infection-induced acute necrotizing encephalopathy as demonstrated in characteristic neuroimaging findings.

Rac1-PAK1 regulation of Rab11 cycling promotes junction destabilization

Rac1 GTPase is hyperactivated in tumors and contributes to malignancy. Rac1 disruption of junctions requires its effector PAK1, but the precise mechanisms are unknown. Here, we show that E-cadherin is internalized via micropinocytosis in a PAK1–dependent manner without catenin dissociation and degradation. In addition to internalization, PAK1 regulates E-cadherin transport by fine-tuning Rab small GTPase function. PAK1 phosphorylates a core Rab regulator, RabGDIβ, but not RabGDIα. Phosphorylated RabGDIβ preferentially associates with Rab5 and Rab11, which is predicted to promote Rab retrieval from membranes. Consistent with this hypothesis, Rab11 is activated by Rac1, and inhibition of Rab11 function partially rescues E-cadherin destabilization. Thus, Rac1 activation reduces surface cadherin levels as a net result of higher bulk flow of membrane uptake that counteracts Rab11-dependent E-cadherin delivery to junctions (recycling and/or exocytosis). This unique small GTPase crosstalk has an impact on Rac1 and PAK1 regulation of membrane remodeling during epithelial dedifferentiation, adhesion, and motility.

Inhibition of EZH2 via the STAT3/HOTAIR signalling axis contributes to cell cycle arrest and apoptosis induced by polyphyllin I in human non-small cell lung cancer cells

OBJECTIVE

To explore the potential mechanism of polyphyllin I (PPI)-induced apoptosis in lung cancer cells.

METHODS AND MATERIALS

The pathological changes in lung cancer tissues and paracancerous tissues were first analysed by H&E staining and IHC staining. After PPI treatment, cell viability and apoptosis were detected by MTT assays, cell cycle analyses and flow cytometry. The expression levels of EZH2 and apoptosis-related molecules were evaluated by qRT-PCR and Western blotting.

RESULTS

EZH2 overexpression decreased proapoptotic proteins, and this effect was reversed by PPI. Knockdown of HOTAIR downregulated EZH2 expression, upregulated proapoptotic proteins, and enhanced the effect of PPI treatment. Moreover, knockdown of STAT3 could counteract the effect of HOTAIR overexpression, which significantly increased the expression of EZH2, thus facilitating cell apoptosis in lung cancer.

CONCLUSIONS

PPI induced cell cycle arrest and apoptosis in lung cancer by inhibiting EZH2 through the STAT3/HOTAIR signalling pathway.

RAB14 activates MAPK signaling to promote bladder tumorigenesis

Bladder cancer (BC) is a fatal invasive malignancy accounting for approximately 5% of all cancer deaths in humans; however, the underlying molecular mechanisms and potential targeted therapeutics for BC patients remain unclear. We report herein that RAB14 was overexpressed in BC tissues and cells with high metastatic potential and its abundance was significantly associated with lymph node metastasis (P = 0.001), a high-grade tumor stage (P = 0.009), poor differentiation (P < 0.001) and unfavorable prognoses of BC patients (P = 0.003, log-rank test). Interference by RAB14 mediated a reduction in the TWIST1 protein and inhibited cell migration and invasion (P < 0.05). Moreover, silencing RAB14 reduced cell proliferation and induced apoptosis in vitro and suppressed tumorigenesis in a mouse xenograft model. We demonstrated that RAB14-promoted BC cancer development and progression were associated with activation of mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase signaling through upregulation of MAPK1/MAPK8 and downregulation of dual-specificity protein phosphatase 6/Src homology 2 domain containing transforming protein/Fos proto-oncogene, AP-1 transcription factor subunit (FOS). We provide evidence that RAB14 acts as a tumor promoter and modulates the invasion and metastatic potential of BC cells via activating the MAPK pathway.

Gene expression profiling of spontaneously occurring canine mammary tumours: Insight into gene networks and pathways linked to cancer pathogenesis

Spontaneously occurring canine mammary tumours (CMTs) are the most common neoplasms of unspayed female dogs leading to thrice higher mortality rates than human breast cancer. These are also attractive models for human breast cancer studies owing to clinical and molecular similarities. Thus, they are important candidates for biomarker studies and understanding cancer pathobiology. The study was designed to explore underlying molecular networks and pathways in CMTs for deciphering new prognostic factors and therapeutic targets. To gain an insight into various pathways and networks associated with the development and pathogenesis of CMTs, comparative cDNA microarray expression profiling was performed using CMT tissues and healthy mammary gland tissues. Upon analysis, 1700 and 1287 differentially expressed genes (DEGs, P ≤ 0.05) were identified in malignant and benign tissues, respectively. DEGs identified from microarray analysis were further annotated using the Ingenuity Systems Pathway Analysis (IPA) tool for detection of deregulated canonical pathways, upstream regulators, and networks associated with malignant, as well as, benign disease. Top scoring key networks in benign and malignant mammary tumours were having central nodes of VEGF and BUB1B, respectively. Cyclins & cell cycle regulation and TREM1 signalling were amongst the top activated canonical pathways in CMTs. Other cancer related significant pathways like apoptosis signalling, dendritic cell maturation, DNA recombination and repair, Wnt/β-catenin signalling, etc. were also found to be altered. Furthermore, seven proteins (ANXA2, APOCII, CDK6, GATC, GDI2, GNAQ and MYH9) highly up-regulated in malignant tissues were identified by two-dimensional gel electrophoresis (2DE) and MALDI-TOF PMF studies which were in concordance with microarray data. Thus, the study has uncovered ample number of candidate genes associated with CMTs which need to be further validated as therapeutic targets and prognostic markers.

Identification of CEA-interacting proteins in colon cancer cells and their changes in expression after irradiation

Purpose

The serum carcinoembryonic antigen (CEA) level has been recognized as a prognostic factor in colorectal cancer, and associated with response of rectal cancer to radiotherapy. This study aimed to identify CEA-interacting proteins in colon cancer cells and observe post-irradiation changes in their expression.

Materials and Methods

CEA expression in colon cancer cells was examined by Western blot analysis. Using an anti-CEA antibody or IgG as a negative control, immunoprecipitation was performed in colon cancer cell lysates. CEA and IgG immunoprecipitates were used for liquid chromatography–tandem mass spectrometry (LC-MS/MS) analysis. Proteins identified in the CEA immunoprecipitates but not in the IgG immunoprecipitates were selected as CEA-interacting proteins. After radiation treatment, changes in expression of CEA-interacting proteins were monitored by Western blot analysis.

Results

CEA expression was higher in SNU-81 cells compared with LoVo cells. The membrane localization of CEA limited the immunoprecipitation results and thus the number of CEA-interacting proteins identified. Only the Ras-related protein Rab-6B and lysozyme C were identified as CEA-interacting proteins in LoVo and SNU-81 cells, respectively. Lysozyme C was detected only in SNU-81, and CEA expression was differently regulated in two cell lines; it was down-regulated in LoVo but up-regulated in SNU-81 in radiation dosage-dependent manner.

Conclusion

CEA-mediated radiation response appears to vary, depending on the characteristics of individual cancer cells. The lysozyme C and Rab subfamily proteins may play a role in the link between CEA and tumor response to radiation, although further studies are needed to clarify functional roles of the identified proteins.

Rab14 is overexpressed in ovarian cancers and promotes ovarian cancer proliferation through Wnt pathway

The Rab GTPase family protein Rab14 has been implicated in cancer development. However, its clinical significance in ovarian cancers and its biological effects have not been examined. The present study aims to examine the clinical significance, biological roles, and molecular mechanism of Rab14 in ovarian cancer progression. We examined expression pattern of Rab14 in 122 cases of ovarian cancer specimens using immunohistochemistry and found Rab14 overexpression correlated with FIGO stage (p = 0.0041). We depleted Rab14 in SKOV3 cells using siRNA and overexpressed Rab14 in SW626 cells. Knockdown of Rab14 inhibited cell growth and invasion while its overexpression facilitated cell growth and invasion. In addition, Rab14 overexpression increased paclitaxel resistance in SW626 cells while its depletion reduced drug resistance. Then, we investigated the role of Rab14 in the regulation of WNT/β-catenin signaling, demonstrating Rab14 overexpression regulated GSK3β phosphorylation and nuclear β-catenin accumulation. Rab14 depletion inhibited while its overexpression enhanced TCF transcriptional activity with corresponding change of Wnt target genes including MMP7 and c-myc. Wnt inhibitor abolished the effect of Rab14 on cell proliferation and Wnt target genes. In conclusion, the present study demonstrated that Rab14 promotes aggressiveness of ovarian cancer cell through, at least partly, Wnt signaling pathway.