Mitochondrial autophagosomes as a mechanism of drug resistance in breast carcinoma

Reduction of Mitochondrial Calcium Overload via MKT077-Induced Inhibition of Glucose-Regulated Protein 75 Alleviates Skeletal Muscle Pathology in Dystrophin-Deficient mdx Mice

Duchenne muscular dystrophy is secondarily accompanied by Ca2+ excess in muscle fibers. Part of the Ca2+ accumulates in the mitochondria, contributing to the development of mitochondrial dysfunction and degeneration of muscles. In this work, we assessed the effect of intraperitoneal administration of rhodacyanine MKT077 (5 mg/kg/day), which is able to suppress glucose-regulated protein 75 (GRP75)-mediated Ca2+ transfer from the sarcoplasmic reticulum (SR) to mitochondria, on the Ca2+ overload of skeletal muscle mitochondria in dystrophin-deficient mdx mice and the concomitant mitochondrial dysfunction contributing to muscle pathology. MKT077 prevented Ca2+ overload of quadriceps mitochondria in mdx mice, reduced the intensity of oxidative stress, and improved mitochondrial ultrastructure, but had no effect on impaired oxidative phosphorylation. MKT077 eliminated quadriceps calcification and reduced the intensity of muscle fiber degeneration, fibrosis level, and normalized grip strength in mdx mice. However, we noted a negative effect of MKT077 on wild-type mice, expressed as a decrease in the efficiency of mitochondrial oxidative phosphorylation, SR stress development, ultrastructural disturbances in the quadriceps, and a reduction in animal endurance in the wire-hanging test. This paper discusses the impact of MKT077 modulation of mitochondrial dysfunction on the development of skeletal muscle pathology in mdx mice.

Excessive lipid production shapes glioma tumor microenvironment

Disrupted lipid metabolism is a characteristic of gliomas. This study utilizes an ultrastructural approach to characterize the prevalence and distribution of lipids within gliomas. This study made use of tissue from IDH1 wild type (IDH1-wt) glioblastoma (n = 18) and IDH1 mutant (IDH1-mt) astrocytoma (n = 12) tumors. We uncover a prevalent and intriguing surplus of lipids. The bulk of the lipids manifested as sizable cytoplasmic inclusions and extracellular deposits in the tumor microenvironment (TME); in some tumors the lipids were stored in the classical membraneless spheroidal lipid droplets (LDs). Frequently, lipids accumulated inside mitochondria, suggesting possible dysfunction of the beta-oxidation pathway. Additionally, the tumor vasculature have lipid deposits in their lumen and vessel walls; this lipid could have shifted in from the tumor microenvironment or have been produced by the vessel-invading tumor cells. Lipid excess in gliomas stems from disrupted beta-oxidation and dysfunctional oxidative phosphorylation pathways. The implications of this lipid-driven environment include structural support for the tumor cells and protection against immune responses, non-lipophilic drugs, and free radicals.

Mechanisms of drug resistance in nutrient-depleted colorectal cancer cells: insights into lysosomal and mitochondrial drug sequestration

This Review delves into the mechanisms behind drug resistance in colorectal cancer (CRC), particularly examining the role of nutrient depletion and its contribution to multidrug resistance (MDR). The study highlights metabolic adaptations of cancer cells as well as metabolic adaptations of cancer cells under low nutrient availability, including shifts in glycolysis and lipid metabolism. It emphasizes the significance of MDR1 and its encoded efflux transporter, P-glycoprotein (P-gp/B1), in mediating drug resistance and how pathways such as HIF1α, AKT, and mTOR influence the expression of P-gp/B1 under limited nutrient availability. Additionally, the Review explores the dual roles of autophagy in drug sensitivity and resistance under nutrient limited conditions. It further investigates the involvement of lysosomes and mitochondria, focusing on their roles in drug sequestration and the challenges posed by lysosomal entrapment facilitated by non-enzymatic processes and ABC transporters like P-gp/B1. Finally, the Review underscores the importance of understanding the interplay between drug sequestration, lysosomal functions, nutrient depletion, and MDR1 gene modulation. It suggests innovative strategies, including structural modifications and nanotechnology, as promising approaches to overcoming drug resistance in cancer therapy.

Excessive Lipid Production Shapes Glioma Tumor Microenvironment

Disrupted lipid metabolism is a characteristic of gliomas. This study utilizes an ultrastructural approach to characterize the prevalence and distribution of lipids within gliomas. This study made use of tissue from IDH1 wild type (IDH1-wt) glioblastoma (n = 18) and IDH1 mutant (IDH1-mt) astrocytoma (n = 12) tumors. We uncover a prevalent and intriguing surplus of lipids. The bulk of the lipids manifested as sizable cytoplasmic inclusions and extracellular deposits in the tumor microenvironment (TME); in some tumors the lipids were stored in the classical membraneless spheroidal lipid droplets (LDs). Frequently, lipids accumulated inside mitochondria, suggesting possible dysfunction of the beta-oxidation pathway. Additionally, the tumor vasculature have lipid deposits in their lumen and vessel walls; this lipid could have shifted in from the tumor microenvironment or have been produced by the vessel-invading tumor cells. Lipid excess in gliomas stems from disrupted beta-oxidation and dysfunctional oxidative phosphorylation pathways. The implications of this lipid-driven environment include structural support for the tumor cells and protection against immune responses, non-lipophilic drugs, and free radicals.

Comparative survey of mitochondrial ultrastructure in IDH1-mutant astrocytoma and IDH1-wildtype glioblastoma (GBM)

Gliomas are the most common malignant brain tumors with poor prognosis. The WHO's classification recognizes isocitrate dehydrogenase 1 (IDH1) mutant astrocytoma and IDH1-wildtype glioblastoma (GBM). The IDH1 mutation confers a survival advantage over the wildtype. There are several explanations for the metabolic advantage of the IDH1 mutation, some involve mitochondrial implications. Since an ultrastructural comparison of both tumor genotypes is still lacking, we surveyed the ultrastructural effects of the IDH1 mutation on the mitochondria of the IDH1-mutant astrocytoma (n = 15) and IDH1-wildtype glioblastoma (n = 15) tumors. Our results show that both IDH1 genotypes have degenerate and uncoupled mitochondria; this has not been reported before. The presence of ample lipid inclusions and lipid droplets in the cytoplasm of both genotypes support our conclusion of dysfunctional uncoupled mitochondria. Thus, the IDH1 mutation may have no ultrastructural consequences on the mitochondria, and the aberrant mitochondria in both genotypes may be the result of other unknown mutations. The status of the mitochondria in these genotypes portends a clinical challenge since tumor cells with uncoupled mitochondria are more primitive, aggressive, and considerably treatment resistant.

An Ultrastructural Perspective on Cell Death

In the field of cell death, there is still a wide gap between the molecular models and their ultrastructural phenotypes. Because only very few published works included electron microscopy (EM) images, many ultrastructural features have not yet been incorporated into the descriptions of death modes. Some of the EM features that appear in dying cells have not been incorporated in describing death modes. It includes the accumulation of lipid droplets and glycogen, the appearance of extranuclear chromatin in the cytoplasm, and the various ways mitochondria become damaged. We argue that electron microscopy should be routinely included in these studies because it exposes some new features that molecular studies do not. It has successfully recognized new modes of cell death, such as entosis, methuosis, and paraptosis. Elucidating the precise sequence of events in death modes could be the cornerstone for offering the proper therapy of many diseases by slowing down or stopping the progression of degeneration. This review presents our own experience applying ultrastructural interpretations to death modes and explaining their biochemical implications. We complement the molecular and biochemical data and point out missing features that should be considered and studied.

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.

Smart Stimuli-Responsive and Mitochondria Targeting Delivery in Cancer Therapy

Dysfunction in the mitochondria (Mc) contributes to tumor progression. It is a major challenge to deliver therapeutic agents specifically to the Mc for precise treatment. Smart drug delivery systems are based on stimuli-responsiveness and active targeting. Here, we give a whole list of documented pathways to achieve smart stimuli-responsive (St-) and Mc-targeted DDSs (St-Mc-DDSs) by combining St and Mc targeting strategies. We present the formulations, targeting characteristics of St-Mc-DDSs and clarify their anti-cancer mechanisms as well as improvement in efficacy and safety. St-Mc-DDSs usually not only have Mc-targeting groups, molecules (lipophilic cations, peptides, and aptamers) or materials but also sense the surrounding environment and correspondingly respond to internal biostimulators such as pH, redox changes, enzyme and glucose, and/or externally applied triggers such as light, magnet, temperature and ultrasound. St-Mc-DDSs exquisitely control the action site, increase therapeutic efficacy and decrease side effects of the drug. We summarize the clinical research progress and propose suggestions for follow-up research. St-Mc-DDSs may be an innovative and sensitive precision medicine for cancer treatment.

Mortalin promotes breast cancer malignancy

Mortalin is a member of the heat shock protein 70 (HSP70) family that promotes the development of many cancers. It is reportedly a tumor promoter, but the mechanism of Mortalin in breast cancer is unclear. We designed a series of experiments to explore the correlation between Mortalin and the malignancy of breast cancer, and to assess the potential of Mortalin as a novel therapeutic target in breast cancer. The expression level of Mortalin in breast cancer tissues was detected. Then, we did a series of functional experiment. The findings indicated that Mortalin facilitates the proliferation, metastasis, and endothelial-to-mesenchymal transition (EMT) process of breast cancer. In our research, Mortalin is regulated EMT process and malignant progression of breast cancer through Wnt/β-Catenin signaling pathway. The findings imply that Mortalin significantly promotes the progression of breast cancer malignancy and reduces patient survival, suggesting that Mortalin as a biomarker and prognostic factor in breast cancer.

Folate-targeted PTEN/AKT/P53 signaling pathway promotes apoptosis in breast cancer cells

Objective Folate deficiency is closely related to the occurrence of human tumors and plays an important role in cell growth, differentiation, repair, and host defense. We studied the effects of folic acid on the apoptosis of breast cancer cells (MDA-MB-231) and on the activity of the PTEN/AKT/P53 signaling pathway in breast cancer cells.

Methods Breast cancer cells (MDA-MB-231) were treated with folate alone or in combination with a PTEN specific inhibitor, SF1670. Cell viability was detected by a MTT assay, and the expression levels of apoptosis-related proteins and PTEN/AKT/P53 signaling pathway were detected via Western blot analysis. Rate of apoptosis was measured via cytometry.

Results Folic acid inhibited the cell viability of MDAMB-231 cells and the expressions of Bcl-2 and p-AKT proteins and upregulate the expression of Bax, PTEN, and P53 proteins, thereby inducing apoptosis in these cells. SF1670 treatment inhibited the expressions of Bcl-2 and p-AKT protein and upregulate Bax, PTEN, and P53 protein expression.

Conclusion Folic acid has cytotoxic effects on MDAMB-231 cells and can induce apoptosis by targeting the PTEN/AKT/P53 signaling pathway.

Modulation of Diacylglycerol-Induced Melanogenesis in Human Melanoma and Primary Melanocytes: Role of Stress Chaperone Mortalin

Skin color/pigmentation is regulated through melanogenesis process in specialized melanin-producing cells, melanocytes, involving multiple signaling pathways. It is highly influenced by intrinsic and extrinsic factors such as oxidative, ultraviolet radiations and other environmental stress conditions. Besides determining the color, it governs response and tolerance of skin to a variety of environmental stresses and pathological conditions including photodamage, hyperpigmentation, and skin cancer. Depigmenting reagents have been deemed useful not only for cosmetics but also for pigmentation-related pathologies. In the present study, we attempted modulation of 1-oleoyl-2-acetyl-glycerol- (OAG-) induced melanogenesis in human melanoma and primary melanocytes. In both cell types, OAG-induced melanogenesis was associated with increase in enhanced expression of melanin, tyrosinase, as well as stress chaperones (mortalin and HSP60) and Reactive Oxygen Species (ROS). Treatment with TXC (trans-4-(Aminomethyl) cyclohexanecarboxylic acid hexadecyl ester hydrochloride) and 5/40 natural compounds resulted in their reduction. The data proposed an important role of mortalin and oxidative stress in skin pigmentation and the use of TXC and natural extracts for modulation of pigmentation pathways in normal and pathological conditions.