Why is Mortalin a Potential Therapeutic Target for Cancer?

Mixtures of Three Mortaparibs with Enhanced Anticancer, Anti-Migration, and Antistress Activities: Molecular Characterization in p53-Null Cancer Cells

Mortalin, a member of the Hsp70 family of proteins, is commonly enriched in many types of cancers. It promotes carcinogenesis and metastasis in multiple ways of which the inactivation of the tumor suppressor activity of p53 has been firmly established. The downregulation of mortalin and/or disruption of mortalin-p53 interactions by small molecules has earlier been shown to activate p53 function yielding growth arrest/apoptosis in cancer cells. Mortaparibs (Mortaparib, MortaparibPlus, and MortaparibMild) are chemical inhibitors of mortalin isolated by cell-based two-way screening involving (i) a shift in the mortalin staining pattern from perinuclear (characteristics of cancer cells) to pancytoplasmic (characteristics of normal cells) and (ii) the nuclear enrichment of p53. They have similar structures and also cause the inhibition of PARP1 and hence were named Mortaparibs. In the present study, we report the anticancer and anti-metastasis activity of MortaparibMild (4-[(4-amino-5-thiophen-2-yl-1,2,4-triazol-3-yl)sulfanylmethyl]-N-(4-methoxyphenyl)-1,3-thiazol-2-amine) in p53-null cells. By extensive molecular analyses of cell proliferation, growth arrest, and apoptosis pathways, we demonstrate that although it causes relatively weaker cytotoxicity compared to Mortaparib and MortaparibPlus, its lower concentrations were equally potent to inhibit cell migration. We developed combinations (called MortaparibMix-AP, MortaparibMix-AM, and MortaparibMix-AS) consisting of different ratios of three Mortaparibs for specifically enhancing their anti-proliferation, anti-migration, and antistress activities, respectively. Based on the molecular analyses of control and treated cells, we suggest that the three Mortaparibs and their mixtures may be considered for further laboratory and clinical studies validating their use for the treatment of cancer as well as prevention of its relapse and metastasis.

Mortalin promotes the evolution of androgen-independent prostate cancer through Wnt/β-catenin signaling pathway

Prostate cancer (PC) is a major global health concern affecting male individuals. Among its variants, androgen-independent prostate cancer exhibits slow progression and lacks effective treatment targets, rendering it insensitive to hormone therapy. Recent reports have highlighted the significance of Mortalin, an important oncogene, in tumor migration and invasion through various signaling pathways. Experimental evidence from in-vivo and in-vitro studies indicate upregulated expression of Mortalin in prostate cancer tissues. Moreover, it has been shown to regulate the epithelial-mesenchymal transition (EMT) process via the Wnt/β-catenin signaling pathway, thereby promoting prostate cancer proliferation and metastasis. These findings suggest that Mortalin may serve as a promising novel immunotherapeutic target for prostate cancer.

Polydatin and Nicotinamide Rescue the Cellular Phenotype of Mitochondrial Diseases by Mitochondrial Unfolded Protein Response (mtUPR) Activation

Primary mitochondrial diseases result from mutations in nuclear DNA (nDNA) or mitochondrial DNA (mtDNA) genes, encoding proteins crucial for mitochondrial structure or function. Given that few disease-specific therapies are available for mitochondrial diseases, novel treatments to reverse mitochondrial dysfunction are necessary. In this work, we explored new therapeutic options in mitochondrial diseases using fibroblasts and induced neurons derived from patients with mutations in the GFM1 gene. This gene encodes the essential mitochondrial translation elongation factor G1 involved in mitochondrial protein synthesis. Due to the severe mitochondrial defect, mutant GFM1 fibroblasts cannot survive in galactose medium, making them an ideal screening model to test the effectiveness of pharmacological compounds. We found that the combination of polydatin and nicotinamide enabled the survival of mutant GFM1 fibroblasts in stress medium. We also demonstrated that polydatin and nicotinamide upregulated the mitochondrial Unfolded Protein Response (mtUPR), especially the SIRT3 pathway. Activation of mtUPR partially restored mitochondrial protein synthesis and expression, as well as improved cellular bioenergetics. Furthermore, we confirmed the positive effect of the treatment in GFM1 mutant induced neurons obtained by direct reprogramming from patient fibroblasts. Overall, we provide compelling evidence that mtUPR activation is a promising therapeutic strategy for GFM1 mutations.

Circulating mortalin in blood and activation of the alternative complement pathway as risk indicators in COVID-19 infection

Background

Mortalin/GRP75 is a ubiquitous mitochondrial chaperone related to the cytosolic heat shock protein 70. It protects cells from various types of damages and from senescence. Our goal was to determine whether COVID-19 patients have circulating mortalin in their blood and to assess its prognostic value in anticipating disease severity.

Methods

Mortalin was determined by ELISA in the sera of 83 COVID-19 patients enrolled in the study. Patients were categorized into 4 groups: critical patients who died (FATAL) or required intensive care and survived (ICU), patients of mild severity (hospitalized but not critical) who required nasal oxygen support (HOSP+O2), and patients who did not need oxygen therapy (HOSP).

Results

The mortalin concentration in the serum of all COVID-19 patients in the cohort was 194-2324 pg/mL. A comparison of the mortalin levels by peak severity among the various patient groups showed a highly significant difference between the HOSP and FATAL groups and a significant difference between the HOSP and the ICU groups. COVID-19 patients who eventually failed to survive had at hospitalization a markedly higher level of mortalin in their sera. Cox regression analysis revealed a high mortality hazard (HR=3.96, p<0.01) in patients with high mortalin circulating levels (above the median, ≥651 pg/mL). This was confirmed in survival curve analysis (Kaplan-Meier; p=0.0032, log-rank test). Mortalin remained an independent predictor of mortality even after adjusting for age and sex or various complement activation products. Complement activation data collected in an earlier study in the same cohort was compared regarding the mortalin levels. Patients with higher circulating mortalin levels also had higher levels of complement C3a but reduced levels of properdin.

Discussion

This is the first report on circulating mortalin in COVID-19 patients. Higher mortalin levels were associated with more severe illnesses and a higher risk of death. We claim that quantifying the blood levels of mortalin and activated complement proteins will provide important information on the prognosis of COVID-19 patients and will serve as a useful tool for guiding their clinical management and treatment.

Cucurbitacin-B inhibits cancer cell migration by targeting mortalin and HDM2: computational and in vitro experimental evidence

Cancer metastasis, a highly complex process wherein cancer cells move from the primary site to other sites in the body, is a major hurdle in its therapeutics. A large array of synthetic chemotherapeutic molecules used for the treatment of metastatic cancers, besides being extremely expensive and unaffordable, are known to cause severe adverse effects leading to poor quality of life (QOL) of the patients. In this premise, natural compounds (considered safe, easily available and economic) that possess the potential to inhibit migration of cancer cells are deemed useful and hence are on demand. Cucurbitacin-B (19-(10→9β)-abeo-10-lanost-5-ene triterpene, called Cuc-B) is a steroid mostly found in plants of Cucurbitaceae family. It has been shown to possess anticancer activity although the molecular mechanism remains poorly defined. We present evidence that Cuc-B has the ability to interact with mortalin and HDM2 proteins that are enriched in cancer cells, suppress wild type p53 function and promote cancer cell migration. Computational analyses showed that Cuc-B interacts with mortalin similar to MKT077 and Withanone, both have been shown to reactivate p53 function and inhibit cell migration. Furthermore, Cuc-B interacted with HDM2 similar to Y30, a well-known inhibitor of HDM2. Experimental cell and molecular analyses demonstrated the downregulation of several proteins, critically involved in cell migration in Cuc-B (low non-toxic doses)-treated cancer cells and exhibited inhibition of cell migration. The data suggested that Cuc-B is a potential natural drug that warrants further mechanistic and clinical studies for its use in the management of metastatic cancers.Communicated by Ramaswamy H. Sarma.

Mitochondrial Quality Control via Mitochondrial Unfolded Protein Response (mtUPR) in Ageing and Neurodegenerative Diseases

Mitochondria play a key role in cellular functions, including energy production and oxidative stress regulation. For this reason, maintaining mitochondrial homeostasis and proteostasis (homeostasis of the proteome) is essential for cellular health. Therefore, there are different mitochondrial quality control mechanisms, such as mitochondrial biogenesis, mitochondrial dynamics, mitochondrial-derived vesicles (MDVs), mitophagy, or mitochondrial unfolded protein response (mtUPR). The last item is a stress response that occurs when stress is present within mitochondria and, especially, when the accumulation of unfolded and misfolded proteins in the mitochondrial matrix surpasses the folding capacity of the mitochondrion. In response to this, molecular chaperones and proteases as well as the mitochondrial antioxidant system are activated to restore mitochondrial proteostasis and cellular function. In disease contexts, mtUPR modulation holds therapeutic potential by mitigating mitochondrial dysfunction. In particular, in the case of neurodegenerative diseases, such as primary mitochondrial diseases, Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), Amyotrophic Lateral Sclerosis (ALS), or Friedreich's Ataxia (FA), there is a wealth of evidence demonstrating that the modulation of mtUPR helps to reduce neurodegeneration and its associated symptoms in various cellular and animal models. These findings underscore mtUPR's role as a promising therapeutic target in combating these devastating disorders.

Unveiling the dark side of glucose-regulated protein 78 (GRP78) in cancers and other human pathology: a systematic review

Glucose-Regulated Protein 78 (GRP78) is a chaperone protein that is predominantly expressed in the lumen of the endoplasmic reticulum. GRP78 plays a crucial role in protein folding by assisting in the assembly of misfolded proteins. Under cellular stress conditions, GRP78 can translocate to the cell surface (csGRP78) were it interacts with different ligands to initiate various intracellular pathways. The expression of csGRP78 has been associated with tumor initiation and progression of multiple cancer types. This review provides a comprehensive analysis of the existing evidence on the roles of GRP78 in various types of cancer and other human pathology. Additionally, the review discusses the current understanding of the mechanisms underlying GRP78's involvement in tumorigenesis and cancer advancement. Furthermore, we highlight recent innovative approaches employed in downregulating GRP78 expression in cancers as a potential therapeutic target.

Synthetic Small Molecule Modulators of Hsp70 and Hsp40 Chaperones as Promising Anticancer Agents

A class of chaperones dubbed heat shock protein 70 (Hsp70) possesses high relevance in cancer diseases due to its cooperative activity with the well-established anticancer target Hsp90. However, Hsp70 is closely connected with a smaller heat shock protein, Hsp40, forming a formidable Hsp70-Hsp40 axis in various cancers, which serves as a suitable target for anticancer drug design. This review summarizes the current state and the recent developments in the field of (semi-)synthetic small molecule inhibitors directed against Hsp70 and Hsp40. The medicinal chemistry and anticancer potential of pertinent inhibitors are discussed. Since Hsp90 inhibitors have entered clinical trials but have exhibited severe adverse effects and drug resistance formation, potent Hsp70 and Hsp40 inhibitors may play a significant role in overcoming the drawbacks of Hsp90 inhibitors and other approved anticancer drugs.

The Challenges and Prospects of p53-Based Therapies in Ovarian Cancer

It has been well established that mutations in the tumor suppressor gene, p53, occur readily in a vast majority of cancer tumors, including ovarian cancer. Typically diagnosed in stages three or four, ovarian cancer is the fifth leading cause of death in women, despite accounting for only 2.5% of all female malignancies. The overall 5-year survival rate for ovarian cancer is around 47%; however, this drops to an abysmal 29% for the most common type of ovarian cancer, high-grade serous ovarian carcinoma (HGSOC). HGSOC has upwards of 96% of cases expressing mutations in p53. Therefore, wild-type (WT) p53 and p53-based therapies have been explored as treatment options via a plethora of drug delivery vehicles including nanoparticles, viruses, polymers, and liposomes. However, previous p53 therapeutics have faced many challenges, which have resulted in their limited translational success to date. This review highlights a selection of these historical p53-targeted therapeutics for ovarian cancer, why they failed, and what the future could hold for a new generation of this class of therapies.

mtUPR Modulation as a Therapeutic Target for Primary and Secondary Mitochondrial Diseases

Mitochondrial dysfunction is a key pathological event in many diseases. Its role in energy production, calcium homeostasis, apoptosis regulation, and reactive oxygen species (ROS) balance render mitochondria essential for cell survival and fitness. However, there are no effective treatments for most primary and secondary mitochondrial diseases to this day. Therefore, new therapeutic approaches, such as the modulation of the mitochondrial unfolded protein response (mtUPR), are being explored. mtUPRs englobe several compensatory processes related to proteostasis and antioxidant system mechanisms. mtUPR activation, through an overcompensation for mild intracellular stress, promotes cell homeostasis and improves lifespan and disease alterations in biological models of mitochondrial dysfunction in age-related diseases, cardiopathies, metabolic disorders, and primary mitochondrial diseases. Although mtUPR activation is a promising therapeutic option for many pathological conditions, its activation could promote tumor progression in cancer patients, and its overactivation could lead to non-desired side effects, such as the increased heteroplasmy of mitochondrial DNA mutations. In this review, we present the most recent data about mtUPR modulation as a therapeutic approach, its role in diseases, and its potential negative consequences in specific pathological situations.

Synthesis, docking studies, biological activity of carbon monoxide release molecules based on coumarin derivatives

In the present work, we synthesized seven complexes. All complexes were identified by ESI-HRMS, ¹H-NMR, ¹⁹F-NMR and ¹³C-NMR spectroscopies. The synthesized complexes were tested for their anticancer activities in vitro against three different human cell lines, including breast MDAMB231, cervical Hela, liver HepG2. IC₅₀ values of complexes 1-7 were 34.98–667.35 µM. Complex 5 revealed higher sensitivity towards MDAMB231 cells with IC₅₀ values 34.98 μM in comparison to 5-FU as positive control. Moreover, complex 5 caused a decrease of mitochondrial membrane potential and effectively induced ROS production against MDAMB231 cells. Western blot analysis showed that complex 5 could up-regulate the expression of Bax protein and down-regulate the expression of Bcl-2, activate Caspase-3, slightly down-regulate the expression of HO-1. The docking studies showed that complex 5 could be interacted with Bcl-2 protein through hydrophobic interactions, hydrogen bonds and salt bridges to enhance the binding affinity. All the analyzed coumarins obeyed the Lipinski’s rule of five for orally administered drugs. Based on the aforementioned results, it suggests that the complex induced apoptosis cell via mitochondria pathways. Collectively, complex 5 could be considered as a promising hit for new anti-breast cancer agents. Carbonyl cobalt CORMs, as potential anticancer therapeutic agents, provided a new idea for the development of metal anticancer drugs.