Cripto-1/Glucose-Regulated Protein 78 Affects Proliferation, Migration and Apoptosis of Ovarian Carcinoma Cells

Background: The Cripto-1 (CR-1)/glucose-regulated protein 78 (GRP78) complex was involved in enhancing survival in different types of cells. CR-1 presented increased levels in ovarian carcinoma tissue. However, the potential mechanism of CR-1/GRP78 was unclear in ovarian cancer. Thus, the study aimed to analyze the role of CR-1/GRP78 in ovarian carcinoma cells. Methods and materials: The CR-1 and GRP78 expression in different ovarian cancer cell lines were detected by RT-qPCR and Western blot (WB). Immunoprecipitation assay was performed to analyze whether Cripto-1 interacted with GRP78. The CR-1 interfering plasmids or GRP-78 overexpressing plasmids transfected into cells were used to decrease endogenous CR-1 levels and increase GRP-78 levels. Cell clonogenicity and proliferation capabilities were separately evaluated by clone growth assay, along with the detection of cell migration and invasion abilities by transwell and wound healing assay. In addition, Matrix Metalloproteinases (MMPs) levels were detected by WB. The cell apoptosis was analyzed by Flow Cytometer and the detection of apoptosis-related proteins. Results: The results showed that CR-1 and GRP78 levels were higher in SKOV3 than other cell lines. Furthermore, CR-1 interacted with GRP78 in cells, which formed protein complex. CR-1 silence significantly decreased GRP-78 levels. Moreover, GRP78 overexpression blocked the anti-survival effects caused by CR-1 knockdown. Conclusion: CR-1 silence inhibited cell proliferation and promoted apoptosis via GRP78. It replied that GRP-78 overexpression might enhance the biological functions of CR-1/GRP78 complex ameliorated by CR-1 silence. Thus, CR-1/GRP78 could be a potential target for treating ovarian carcinoma.

HSP70s in Breast Cancer: Promoters of Tumorigenesis and Potential Targets/Tools for Therapy

The high frequency of breast cancer worldwide and the high mortality among women with this malignancy are a serious challenge for modern medicine. A deeper understanding of the mechanisms of carcinogenesis and emergence of metastatic, therapy-resistant breast cancers would help development of novel approaches to better treatment of this disease. The review is dedicated to the role of members of the heat shock protein 70 subfamily (HSP70s or HSPA), mainly inducible HSP70, glucose-regulated protein 78 (GRP78 or HSPA5) and GRP75 (HSPA9 or mortalin), in the development and pathogenesis of breast cancer. Various HSP70-mediated cellular mechanisms and pathways which contribute to the oncogenic transformation of mammary gland epithelium are reviewed, as well as their role in the development of human breast carcinomas with invasive, metastatic traits along with the resistance to host immunity and conventional therapeutics. Additionally, intracellular and cell surface HSP70s are considered as potential targets for therapy or sensitization of breast cancer. We also discuss a clinical implication of Hsp70s and approaches to targeting breast cancer with gene vectors or nanoparticles downregulating HSP70s, natural or synthetic (small molecule) inhibitors of HSP70s, HSP70-binding antibodies, HSP70-derived peptides, and HSP70-based vaccines.

2-Amino-3-Methylimidazo[4,5-f]quinoline Triggering Liver Damage by Inhibiting Autophagy and Inducing Endoplasmic Reticulum Stress in Zebrafish (Danio rerio)

It is important to note that 2-Amino-3-methylimidazole[4,5-f]quinoline (IQ) is one of the most common heterocyclic amines (HCAs), which is a class of mutagenic/carcinogenic harmful compounds mainly found in high-protein thermal processed foods and contaminated environments. However, the pre-carcinogenic toxicity of IQ to the liver and its mechanism are poorly understood, further research is needed. In light of this, we exposed zebrafish to IQ (0, 8, 80, and 800 ng/mL) for 35 days, followed by comprehensive experimental studies. Histopathological and ultrastructural analysis showed that hepatocytes were damaged. TUNEL results showed that IQ induced apoptosis of liver cells, the expression of apoptosis factor gene was significantly increased, and the expression of Bcl-2 protein was significantly decreased. In addition, upregulated expression of the 78-kDa glucose-regulated protein (GRP78) and C/EBP homologous protein (CHOP) and endoplasmic reticulum stress (ERS)-related factors transcription levels were elevated obviously, suggesting that IQ induced ERS. Decreased protein expression of autophagy-related 5 (Atg5)-Atg12, Beclin1, and LC3-II, increased protein expression of p62, and autophagy-related factors transcription levels were significantly decreased, suggesting that IQ inhibited autophagy. Overall, our research showed that the potential harm of IQ to the liver before the occurrence of liver cancer was related to ERS and its mediated autophagy and apoptosis pathways.

Structural-Dynamics and Binding Analysis of RBD from SARS-CoV-2 Variants of Concern (VOCs) and GRP78 Receptor Revealed Basis for Higher Infectivity

Glucose-regulated protein 78 (GRP78) might be a receptor for SARS-CoV-2 to bind and enter the host cell. Recently reported mutations in the spike glycoprotein unique to the receptor-binding domain (RBD) of different variants might increase the binding and pathogenesis. However, it is still not known how these mutations affect the binding of RBD to GRP78. The current study provides a structural basis for the binding of GRP78 to the different variants, i.e., B.1.1.7, B.1.351, B.1.617, and P.1 (spike RBD), of SARS-CoV-2 using a biomolecular simulation approach. Docking results showed that the new variants bound stronger than the wild-type, which was further confirmed through the free energy calculation results. All-atom simulation confirmed structural stability, which was consistent with previous results by following the global stability trend. We concluded that the increased binding affinity of the B.1.1.7, B.1.351, and P.1 variants was due to a variation in the bonding network that helped the virus induce a higher infectivity and disease severity. Consequently, we reported that the aforementioned new variants use GRP78 as an alternate receptor to enhance their seriousness.

5-Aminolevulinic Acid Attenuates Glucose-Regulated Protein 78 Expression and Hepatocyte Lipoapoptosis via Heme Oxygenase-1 Induction

Endoplasmic reticulum (ER) stress plays a pivotal role in the progression of steatohepatitis. 5-aminolevulinic acid (5-ALA), a precursor in the heme biosynthetic pathway, has recently been reported to induce heme oxygenase (HO)-1. HO-1 exerts important cytoprotective actions. In this study, we aimed to explore the therapeutic potential of 5-ALA on palmitate-induced ER stress and lipoapoptosis. Huh-7 cells were treated with palmitic acid (PA) (800 μM) to induce steatosis for eight hours. Steatosis was evaluated by Lipi-green staining. 5-ALA (200 μM) was added with PA. The gene expression levels of the nuclear factor erythroid 2–related factor 2 (NRF2), HO-1, Glucose-regulated protein 78 (GRP78), activating transcription factor 6 (ATF6), PKR-like endoplasmic reticulum kinase (PERK), inositol-requiring enzyme 1 (IRE1), C/EBP homologous protein (CHOP), and B-cell lymphoma 2 (BCL-2) were evaluated by RT-PCR. Caspase-3/7 activity was evaluated by fluorescein active Caspase-3/7 staining. Cell death was evaluated by Annexin V/SYTOX green staining. PA significantly induced steatosis and increased GRP78 expression in Huh-7 cells. 5-ALA significantly induced HO-1 and decreased GRP78 expression. ATF6 was subsequently decreased. However, NRF2 and CHOP expression were not altered. Anti-apoptotic BCL-2 expression significantly increased, and Caspase 3/7 activity and cell death also decreased. 5-ALA has a therapeutic potential on hepatic steatosis by suppressing ER stress and lipoapoptosis by attenuating GRP78 via HO-1 induction.

Endoplasmic Reticulum Chaperones in Viral Infection: Therapeutic Perspectives

Viruses are intracellular parasites that subvert the functions of their host cells to accomplish their infection cycle. The endoplasmic reticulum (ER)-residing chaperone proteins are central for the achievement of different steps of the viral cycle, from entry and replication to assembly and exit. The most abundant ER chaperones are GRP78 (78-kDa glucose-regulated protein), GRP94 (94-kDa glucose-regulated protein), the carbohydrate or lectin-like chaperones calnexin (CNX) and calreticulin (CRT), the protein disulfide isomerases (PDIs) and the DNAJ chaperones.

Brain adiponectin signaling controls peripheral insulin response in Drosophila

The brain plays a key role in energy homeostasis, detecting nutrients, metabolites and circulating hormones from peripheral organs and integrating this information to control food intake and energy expenditure. Here, we show that a group of neurons in the Drosophila larval brain expresses the adiponectin receptor (AdipoR) and controls systemic growth and metabolism through insulin signaling. We identify glucose-regulated protein 78 (Grp78) as a circulating antagonist of AdipoR function produced by fat cells in response to dietary sugar. We further show that central AdipoR signaling inhibits peripheral Juvenile Hormone (JH) response, promoting insulin signaling. In conclusion, we identify a neuroendocrine axis whereby AdipoR-positive neurons control systemic insulin response.

Deficient synthesis of melatonin in COVID-19 can impair the resistance of coronavirus patients to mucormycosis

Though it is thought that uncontrolled diabetes and the excessive use of corticosteroids are responsible for COVID-19 associated mucormycosis (CAM), researchers are on the lookout for additional reasons to explain the recent spurt of CAM in India. In the present paper it is argued that melatonin deficiency in COVID-19 plays a major role in CAM. Incidentally, melatonin is synthesized from tryptophan via the serotonin pathway and melatonin deficiency in COVID-19 arises from the faulty absorption of tryptophan from the food because SARS-COV-2 downregulates angiotensin-converting enzyme-2, which is the chaperone of the transporter of tryptophan, a key component in the process of uptake of tryptophan. The melatonin deficiency enhances the fungal virulence by facilitating iron acquisition and by promoting morphological transition of the mucor species from the yeast to the virulent hyphal form. Additionally, melatonin deficiency aggravates the suppression of T-cell immunity in the patients receiving steroids. Hence, the restoration of melatonin level should resolve the issues and help in defeating CAM, given the fact that melatonin is an iron chelator, inhibitor of myeloperoxidase, inhibitor of ferroptosis and pyroptosis and calmodulin blocker. Also, by lowering the expression of glucose-regulated protein-78, melatonin can further increase the resistance of diabetic patients to mucormycosis. Hence, clinical trials should be carried out to ascertain how tryptophan supplementation, administration of selective serotonin reuptake inhibitors (to increase serotonin, the precursor of melatonin), and exogenous melatonin help in correcting the melatonin deficiency and eliminating or reducing the propensity of the patients to CAM.