Mitochondrial HER2 stimulates respiration and promotes tumorigenicity

BACKGROUND

Amplification of HER2, a receptor tyrosine kinase and a breast cancer-linked oncogene, is associated with aggressive disease. HER2 protein is localised mostly at the cell membrane, but a fraction translocates to mitochondria. Whether and how mitochondrial HER2 contributes to tumorigenicity is currently unknown.

METHODS

We enriched the mitochondrial (mt-)HER2 fraction in breast cancer cells using an N-terminal mitochondrial targeting sequence and analysed how this manipulation impacts bioenergetics and tumorigenic properties. The role of the tyrosine kinase activity of mt-HER2 was assessed in wild type, kinase-dead (K753M) and kinase-enhanced (V659E) mtHER2 constructs.

RESULTS

We document that mt-HER2 associates with the oxidative phosphorylation system, stimulates bioenergetics and promotes larger respiratory supercomplexes. mt-HER2 enhances proliferation and invasiveness in vitro and tumour growth and metastatic potential in vivo, in a kinase activity-dependent manner. On the other hand, constitutively active mt-HER2 provokes excessive mitochondria ROS generation, sensitises to cell death, and restricts growth of primary tumours, suggesting that regulation of HER2 activity in mitochondria is required for the maximal pro-tumorigenic effect.

CONCLUSIONS

mt-HER2 promotes tumorigenicity by supporting bioenergetics and optimal redox balance.

MicroRNA-495: a therapeutic and diagnostic tumor marker

Therapeutic and diagnostic progresses have significantly reduced the mortality rate among cancer patients during the last decade. However, there is still a high rate of mortality among cancer patients. One of the important reasons involved in the high mortality rate is the late diagnosis in advanced tumor stages that causes the failure of therapeutic strategies in these patients. Therefore, investigating the molecular mechanisms involved in tumor progression has an important role in introducing the efficient early detection markers. MicroRNAs (miRNAs) as stable factors in body fluids are always considered as non-invasive diagnostic and prognostic markers. In the present review, we investigated the role of miR-495 in tumor progression. It has been reported that miR-495 has mainly a tumor suppressor function through the regulation of transcription factors and tyrosine kinases as well as cellular processes such as multidrug resistance, chromatin remodeling, and signaling pathways. This review can be an effective step towards introducing the miR-495 as a non-invasive diagnostic/prognostic marker as well as a suitable target in tumor therapy.

SPI1 Mediates N-Myristoyltransferase 1 to Advance Gastric Cancer Progression via PI3K/AKT/mTOR Pathway

Gastric cancer (GC) is a common digestive tract malignancy worldwide. N-myristoyltransferase 1 (NMT1) has been implicated in many cancers, but its association with gastric cancer remains to be clarified. Thus, this paper elucidated the role of NMT1 in GC. The NMT1 expression level in GC and normal tissue samples as well as the relationship between NMT1 high or low expression and overall survival in GC was analyzed via GEPIA. GC cells were transfected with NMT1 or SPI1 overexpression plasmid and short hairpin RNA against NMT1 (shNMT1) or shSPI1. NMT1, SPI1, p-PI3K, PI3K, p-AKT, AKT, p-mTOR, and mTOR levels were detected through qRT-PCR and western blot. MTT, wound healing, and transwell assays were applied to test cell viability, migration, and invasion. The binding relationship of SPI1 and NMT1 was determined through a dual-luciferase reporter assay and chromatin immunoprecipitation. NMT1 was upregulated in GC, the high level of which connected with a poor prognosis. Overexpressed NMT1 elevated viability, migration rate, and invasion rate of GC cells, whereas NMT1 knockdown leads to the opposite results. Besides, SPI1 could bind to NMT1. Overexpressed NMT1 reversed the effects of shSPI1 on decreasing viability, migration, invasion, p-PI3K/PI3K, p-AKT/AKT, and p-mTOR/mTOR in GC cells, and NMT1 knockdown reversed the effects of SPI1 overexpression on increasing viability, migration, invasion, p-PI3K/PI3K, p-AKT/AKT, and p-mTOR/mTOR. SPI1 upregulated NMT1 to facilitate the malignant behaviors of GC cells through the PI3K/AKT/mTOR pathway.

Guf1 overexpression improves pancreatic β cell functions in type 2 diabetes mellitus rats with Roux-en-Y gastric bypass (RYGB) surgery

The Roux-en-Y gastric bypass (RYGB) is a one-of-a-kind treatment among contemporary bariatric surgical procedures, and its therapeutic effects for type 2 diabetes mellitus (T2DM) are satisfactory. The present study performed isobaric tags for relative and absolute quantification (iTRAQ) combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis identifying different proteomics between T2DM rats with or without Roux-en-Y gastric bypass (RYGB) surgery, and GTP binding elongation factor GUF1 (Guf1) was first found to be significantly upregulated in rats from the T2DM plus RYGB group. In the cellular lipotoxicity model induced by palmitic acid stimulation of rat pancreatic beta cell line, INS-1, palmitic acid treatment inhibited cell viability, suppressed GSIS, promoted lipid droplet formation, promoted cell apoptosis, and induced mitochondrial membrane potential loss. The effects of palmitic acid on INS-1 cells mentioned above could be partially eliminated by Guf1 overexpression but aggravated by Guf1 knockdown. Last, under palmitic acid treatment, Guf1 overexpression promotes the PI3K/Akt and NF-κB signaling but inhibits the AMPK activation. Guf1 is upregulated in T2DM rats who received RYGB, and Guf1 overexpression improves cell mitochondrial functions, increases cell proliferation, inhibits cell apoptosis, and promotes cell functions in palmitic acid-treated β cells.

Signaling pathways and therapeutic interventions in gastric cancer

Gastric cancer (GC) ranks fifth in global cancer diagnosis and fourth in cancer-related death. Despite tremendous progress in diagnosis and therapeutic strategies and significant improvements in patient survival, the low malignancy stage is relatively asymptomatic and many GC cases are diagnosed at advanced stages, which leads to unsatisfactory prognosis and high recurrence rates. With the recent advances in genome analysis, biomarkers have been identified that have clinical importance for GC diagnosis, treatment, and prognosis. Modern molecular classifications have uncovered the vital roles that signaling pathways, including EGFR/HER2, p53, PI3K, immune checkpoint pathways, and cell adhesion signaling molecules, play in GC tumorigenesis, progression, metastasis, and therapeutic responsiveness. These biomarkers and molecular classifications open the way for more precise diagnoses and treatments for GC patients. Nevertheless, the relative significance, temporal activation, interaction with GC risk factors, and crosstalk between these signaling pathways in GC are not well understood. Here, we review the regulatory roles of signaling pathways in GC potential biomarkers, and therapeutic targets with an emphasis on recent discoveries. Current therapies, including signaling-based and immunotherapies exploited in the past decade, and the development of treatment for GC, particularly the challenges in developing precision medications, are discussed. These advances provide a direction for the integration of clinical, molecular, and genomic profiles to improve GC diagnosis and treatments.

Coix seed oil regulates mitochondrial functional damage to induce apoptosis of human pancreatic cancer cells via the PTEN/PI3K/AKT signaling pathway

BACKGROUND

Coix seed oil (CSO) has a wide range of anticancer effects. However, the mechanism of action against pancreatic cancer (PC) and regulation of mitochondria in vitro is still unclear.

MATERIALS AND RESULTS

This research investigated the possible mechanism of CSO induction of PC cell apoptosis and regulating mitochondrial functional damage. Proliferation of PC cells, mitochondrial membrane potential (MMP), qualitative and quantitative analysis of PC cell apoptosis, openness of mitochondrial permeability transition pore, related protein expression, generation of reactive oxygen species (ROS), and gene expression were determined by cell counting kit-8, JC-1 staining, acridine orange and ethidium bromide staining, flow cytometry, calcein-AM/cobalt staining, western blotting, dichlorofluorescein diacetate probe, and quantitative real-time reverse transcription-polymerase chain reaction, respectively. We confirmed that PTEN protein was involved in CSO-induced PANC-1 cell apoptosis and mitochondrial functional damage. CSO induced depolarization of MMP, increased opening of the mitochondrial permeability transition pore, increased ROS production, and further increased mitochondrial damage. Additionally, CSO downregulated expression of p-AKT and p-PI3K proteins; upregulated protein expression of cleaved caspase-9, Bax, cleaved caspase-3 and cytochrome c; and downregulated expression of Bcl-2 by upregulating the PTEN gene. The corresponding protein expression was consistent with the gene expression level. Furthermore, the loss of function of PTEN protein reduces the ability of CSO to induce apoptosis of PANC-1 cells and damage to mitochondrial function.

CONCLUSIONS

CSO induces apoptosis of PANC-1 PC cells by modulating mitochondrial functional impairment and related apoptotic molecules via PTEN, which may be closely related to the PI3K/AKT signaling pathway.

Disitamab vedotin: a novel antibody-drug conjugates for cancer therapy

Human epidermal growth factor receptor 2 (HER2) regulates cell mitosis, proliferation, and apoptosis. Trastuzumab is a HER2-targeted monoclonal antibody (mAB), which can prolong the overall survival rate of patients with HER2 overexpression in later periods of gastric cancer and breast cancer. Although anti-HER2 monoclonal antibody has a curative effect, adjuvant chemotherapy is still necessary to upgrade the curative effect maximumly. Antibody-drug conjugate (ADC) is a kind of therapeutic drug that contains antigen-specific antibody and cytotoxic payload, which can improve the survival time of tumor patients. To date, there are several HER2-ADC products on the market, for which two anti-HER2 ADC (trastuzumab emtansine and trastuzumab deruxtecan) have been authorized by the FDA for distinct types of HER2-positive carcinoma in the breast. Disitamab vedotin (RC48) is a newly developed ADC drug targeting HER2 that is comprised of hertuzumab coupling monomethyl auristatin E (MMAE) via a cleavable linker. This paper aims to offer a general insight and summary of the mechanism of action and the currently completed and ongoing clinical studies of RC-48 in HER-2 positive solid tumors.

Effect of Acidosis-Induced Signalling Pathways on Mitochondrial O2 Consumption of Tumour Cells

Signalling pathways such as ERK1/2, p38 or PI3K are activated in tumour cells by extracellular acidosis, which is a common phenomenon in human tumours. These signalling pathways can modulate the mitochondrial function and activity. The aim of the study was to evaluate the impact of extracellular acidosis on the mitochondrial O2 consumption and, in consequence, the potential role of ERK1/2, p38 and PI3K cascades on modulating the respiratory function. The O2 consumption rate (OCR) was measured at pH 7.4 and extracellular acidosis (pH 6.6) in combination with inhibition of the respective signalling pathway. The activity of the pathways was determined by phosphorylation-specific western blot using the cytosolic and mitochondrial fraction of cell lysates. The experiments were performed on a rat tumour cell line (subline AT1 of the rat R-3327 prostate carcinoma) and normal cells (NRK-49F fibroblasts). Acidosis increased the OCR of AT1 cells, especially the basal OCR and the O2 consumption, which is related to ATP production. In normal NRKF cells OCR was unaffected by low pH. Inhibition of ERK1/2 and PI3K, but not p38, reduced the acidosis-induced increase of the OCR significantly in AT1 tumour cells. In this cell line acidosis also led to an ERK1/2 and PI3K activation, predominantly in the mitochondrial fraction. These results indicate that extracellular acidosis activates cellular respiration in tumour cells, presumably by activating the ERK1/2 and/or the PI3K signalling cascade. This activation of ERK1/2 and PI3K is located primarily in the mitochondrial compartment of the cells.

Activation of TLR4 induces severe acute pancreatitis-associated spleen injury via ROS-disrupted mitophagy pathway

Severe acute pancreatitis (SAP) is complicated by systemic inflammatory response syndrome and multiple organ dysfunction, the disease will eventually result in death in almost half of the case. The spleen, as the largest immune organ adjacent to the pancreas, is prone to damage in SAP, thereby aggravating the damage of other organs and increasing mortality. However, to date, the research on the mechanism and treatment of spleen injury caused by SAP is still in its infancy. Herein, we investigated the mechanism of spleen injury, and explored the application potential of tuftsin for relieving spleen damage in SAP mice. Firstly, SAP mice model was constructed via the retrograde infusion of 3.5 % sodium taurocholate into the biliopancreatic duct. Then, we proved that the up-regulation of Toll-like receptor 4 (TLR4) in spleen would lead to the accumulation of reactive oxygen species (ROS) and mitochondrial dysfunction under SAP conditions. The splenic ROS and mitochondrial dysfunction could be improved by N-acetylcysteine (NAC) treatment or knocking out TLR4 in SAP mice. Meanwhile, we found that NAC treatment could also improve the autophagy of spleen tissue, suggesting that splenic ROS may affect impaired autophagy, causing the accumulation of damaged mitochondria, aggravating spleen damage. Furthermore, we verified the mechanism of spleen injury is caused by splenic ROS affecting PI3K/p-AKT/mTOR pathway-mediated autophagy. In addition, we detected the spleen injury caused by SAP could decrease the concentration of tuftsin in the serum of mice. Whereas, exogenous supplementation of tuftsin ameliorated the pathological damage, ROS accumulation, impaired autophagy, inflammation expression and apoptosis in damaged spleen. In summary, we verified the new mechanism of SAP-caused spleen damage that TLR4-induced ROS provoked mitophagy impairment and mitochondrial dysfunction in spleen via PI3K/p-AKT mTOR signaling, and the application potential of tuftsin in treating spleen injury, which might expand novel ideas and methods for the treatment of pancreatitis.

Melatonin enhances SIRT1 to ameliorate mitochondrial membrane damage by activating PDK1/Akt in granulosa cells of PCOS

Mitochondrial injury in granulosa cells (GCs) is associated with the pathophysiological mechanism of polycystic ovary syndrome (PCOS). Melatonin reduces the mitochondrial injury by enhancing SIRT1 (NAD-dependent deacetylase sirtuin-1), while the mechanism remains unclear. Mitochondrial membrane potential is a universal selective indicator of mitochondrial function. In this study, mitochondrial swelling and membrane defect mitochondria in granulosa cells were observed from PCOS patients and DHT-induced PCOS-like mice, and the cytochrome C level in the cytoplasm and the expression of BAX (BCL2-associated X protein) in mitochondria were significantly increased in GCs, with p-Akt decreased, showing mitochondrial membrane was damaged in GCs of PCOS. Melatonin treatment decreased mitochondrial permeability transition pore (mPTP) opening and increased the JC-1 (5,5′,6,6′-tetrachloro1,1′,3,3′-tetramethylbenzimidazolylcarbocyanine iodide) aggregate/monomer ratio in the live KGN cells treated with DHT, indicating melatonin mediates mPTP to increase mitochondrial membrane potential. Furthermore, we found melatonin decreased the levels of cytochrome C and BAX in DHT-induced PCOS mice. PDK1/Akt played an essential role in improving the mitochondrial membrane function, and melatonin treatment increased p-PDK 1 and p-Akt in vivo and in vitro. The SIRT1 was also increased with melatonin treatment, while knocking down SIRT1 mRNA inhibiting the protective effect of melatonin to activate PDK1/Akt. In conclusion, melatonin enhances SIRT1 to ameliorate mitochondrial membrane damage by activating PDK1/Akt in granulosa cells of PCOS.

Mechanism underlying resveratrol's attenuation of paclitaxel cytotoxicity in human breast cancer cells: Role of the SIRT1-FOXO1-HER3 signaling pathway

Resveratrol (RES), a dietary phenolic compound, was reported to have cancer chemoprotective and chemotherapeutic effects. Earlier we unexpectedly observed that RES has a growth-enhancing effect in some breast cancer cells and can diminish the susceptibility of MDA-MB-231 and SKBR-3 cells to paclitaxel-induced cell death, but this phenomenon is not observed in MCF-7 cells. The present study seeks to determine the mechanism underlying RES's attenuation of paclitaxel cytotoxicity in cancer cells. It is found that RES reduces the anticancer action of paclitaxel only in the human breast cancer cells that express HER3 protein. Treatment of SKBR-3 cells with RES increases HER3 expression in a dose-dependent manner. The induction of HER3 expression by RES confers resistance of breast cancer cells against paclitaxel cytotoxicity. Furthermore, it is observed that the SIRT1-FOXO1 signaling pathway plays an important role in mediating RES-induced upregulation of HER3 expression. In conclusion, the present study reveals the mechanism for RES-induced resistance against paclitaxel in some human breast cancer cells, and it is suggested that the combined use of RES and paclitaxel is not suitable for treating human breast cancer that expresses HER3 protein.

Exploring the effect of Gupi Xiaoji Prescription on hepatitis B virus-related liver cancer through network pharmacology and in vitro experiments

AIM AND OBJECTIVE

To study the effect of Gupi Xiaoji Prescription (GXP) on hepatitis B virus(HBV)-related liver cancer through network pharmacology coupled with in vitro experiments and explore their related mechanisms.

MATERIALS AND METHODS

Gupi Xiaoji Prescription's chemical constituents and the action targets of its six medicinal components were identified using several databases. These included the Traditional Chinese Medicine Systems Pharmacology Database （TCMSP), the Bioinformatics Analysis Tool for Molecular mechANism of TCM (BATMAN-TCM), and the Traditional Chinese Medicine Integrated Database (TCMID), while GeneCards and OMIM were used to compile relevant liver cancer disease targets. Pathway enrichment of gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG), analysis of potential targets, and analysis of the enriched pathways in literature were executed in R. The Hepatocellular carcinoma (HCC)-derived HepG2.2.15 cell line stably expresses and replicates HBV. In vitro experiments with HepG2.2.15 were used to verify GXP's effects on HBV-related liver cancer, while the human liver cancer cell line HepG2 was used as the control.

RESULTS

171 active ingredients and 259 potential drug targets were screened from GXP, involving 181 pathways in vitro. These assays identified Polyphyllin I as an effective GXP component. Notably, GXP inhibited cell proliferation and metastasis in a concentration-dependent manner (P < 0.01). In comparison with the vehicle group, the fluorescence intensity of each drug group was significantly weakened (P < 0.01), while the drug group Mitofusins 1(MFN1) and protein expression level of Mitofusins 2 (MFN2) increased significantly. The protein expression level of Mitochondrial fission protein 1 (FIS1) and Optic Atrophy 1 (OPA1) also showed significant decreases (P < 0.01). Molecular docking revealed Fructus saponins I's high affinity with FIS1, MFN1, MFN2, and OPA1.

CONCLUSION

The network pharmacology results indicate that Gupi Xiaoji Prescription may treat liver cancer by regulating mitochondrial division and fusion of key genes to disrupt liver cancer cells' energy metabolism. In vitro experiments also verified that GXP could inhibit the proliferation and migration of HepG2.2.15 cells by up-regulating MFN1 and MFN2, down-regulating the expression of FIS1 and OPA1 in addition to damaging mitochondria. Consistent with network pharmacology and molecular docking results, Polyphyllin I may be the most active compound of the formula's components. It also shows that Traditional Chinese medicine (TCM) plays a significant, targeted role in the treatment of HBV-related liver cancer.

HER2-targeted therapies in gastric cancer

Molecular targeted therapy of cancer has always been the focus of clinicians. Among those therapeutic targets, the human epidermal growth factor receptor-2 (HER-2) signaling pathway is one of the most popular targets for translational research in cancer. However, unlike prospect in breast cancer, HER-2 inhibitor trastuzumab is the only molecular targeted drug approved by US Food and Drug Administration (FDA) for the first-line treatment of HER-2 positive advanced gastric cancer. On this basis, a variety of novel HER2- targeted drugs for gastric cancer are under development, and related clinical researches are in full swing, including small molecular kinase inhibitors (e.g., afatinib, neratinib, pyrotinib), antibody-drug conjugates (e.g., DS-8201a, RC48-ADC) and other novel therapies (e.g., ZW25, CAR-T, BVAC-B). In this study, we will summarize the recent advances in anti-HER-2 agents, potential mechanisms of resistance to HER2-targeted therapy in HER2-positive gastric cancer. We will also discuss the future prospects of potential strategies to overcome anti-HER-2 resistance and development of novel anti-HER-2 approaches for the treatment of HER2-positive gastric cancer patients.

Cancer cell metabolism: Rewiring the mitochondrial hub

To adapt to tumoral environment conditions or even to escape chemotherapy, cells rapidly reprogram their metabolism to handle adversities and survive. Given the rapid rise of studies uncovering novel insights and therapeutic opportunities based on the role of mitochondria in tumor metabolic programing and therapeutics, this review summarizes most significant developments in the field. Taking in mind the key role of mitochondria on carcinogenesis and tumor progression due to their involvement on tumor plasticity, metabolic remodeling, and signaling re-wiring, those organelles are also potential therapeutic targets. Among other topics, we address the recent data intersecting mitochondria as of prognostic value and staging in cancer, by mitochondrial DNA (mtDNA) determination, and current inhibitors developments targeting mtDNA, OXPHOS machinery and metabolic pathways. We contribute for a holistic view of the role of mitochondria metabolism and directed therapeutics to understand tumor metabolism, to circumvent therapy resistance, and to control tumor development.

A New Twist in Protein Kinase B/Akt Signaling: Role of Altered Cancer Cell Metabolism in Akt-Mediated Therapy Resistance

Cancer resistance to chemotherapy, radiotherapy and molecular-targeted agents is a major obstacle to successful cancer therapy. Herein, aberrant activation of the phosphatidyl-inositol-3-kinase (PI3K)/protein kinase B (Akt) pathway is one of the most frequently deregulated pathways in cancer cells and has been associated with multiple aspects of therapy resistance. These include, for example, survival under stress conditions, apoptosis resistance, activation of the cellular response to DNA damage and repair of radiation-induced or chemotherapy-induced DNA damage, particularly DNA double strand breaks (DSB). One further important, yet not much investigated aspect of Akt-dependent signaling is the regulation of cell metabolism. In fact, many Akt target proteins are part of or involved in the regulation of metabolic pathways. Furthermore, recent studies revealed the importance of certain metabolites for protection against therapy-induced cell stress and the repair of therapy-induced DNA damage. Thus far, the likely interaction between deregulated activation of Akt, altered cancer metabolism and therapy resistance is not yet well understood. The present review describes the documented interactions between Akt, its target proteins and cancer cell metabolism, focusing on antioxidant defense and DSB repair. Furthermore, the review highlights potential connections between deregulated Akt, cancer cell metabolism and therapy resistance of cancer cells through altered DSB repair and discusses potential resulting therapeutic implications.

Modulation of Apoptosis by Plant Polysaccharides for Exerting Anti-Cancer Effects: A Review

Cancer has become a significant public health problem with high disease burden and mortality. At present, radiotherapy and chemotherapy are the main means of treating cancer, but they have shown serious safety problems. The severity of this problem has caused further attention and research on effective and safe cancer treatment methods. Polysaccharides are natural products with anti-cancer activity that are widely present in a lot of plants, and many studies have found that inducing apoptosis of cancer cells is one of their important mechanisms. Therefore, this article reviews the various ways in which plant polysaccharides promote apoptosis of cancer cells. The major apoptotic pathways involved include the mitochondrial pathway, the death receptor pathway, and their upstream signal transduction such as MAPK pathway, PI3K/AKT pathway, and NF-κB pathway. Moreover, the paper has also been focused on the absorption and toxicity of plant polysaccharides with reference to extant literature, making the research more scientific and comprehensive. It is hoped that this review could provide some directions for the future development of plant polysaccharides as anticancer drugs in pharmacological experiments and clinical researches.

Enhanced signaling via ERBB3/PI3K plays a compensatory survival role in pancreatic tumor cells exposed to [neratinib + valproate]

The ERBB1/2/4 inhibitor neratinib causes plasma membrane-associated K-RAS to mislocalize into intracellular vesicles; this effect is enhanced by HDAC inhibitors and the combination of [neratinib + sodium valproate] is now a phase I trial (NCT03919292). The present studies were performed to understand resistance mechanisms that evolve following [neratinib + valproate] exposure. Exposure of pancreatic tumor cells to [neratinib + sodium valproate] initially reduced the expression and phosphorylation of ERBB family receptors, c-MET and c-KIT. Following a 24 h drug exposure and a further 24 h culture in drug free conditions, the effects on c-MET, c-KIT and most ERBB family receptors had returned to near baseline levels. However, the expression and phosphorylation of ERBB3 were increased which was associated with elevated AKT T308 phosphorylation. Knock down of ERBB3 significantly enhanced [neratinib + valproate] lethality, which was associated with greater inactivation of AKT, mTOR, p70 S6K and ERK1/2. The PI3Kα/δ inhibitor copanlisib also significantly enhanced killing after [neratinib + valproate] exposure. Copanlisib enhanced [neratinib + valproate] lethality via autophagosome formation and autophagic flux. Our data argue for further in vivo exploration as to whether copanlisib can be safely combined with [neratinib + valproate].

An Intelligent DNA Nanorobot with in Vitro Enhanced Protein Lysosomal Degradation of HER2

DNA nanorobots have emerged as new tools for nanomedicine with the potential to ameliorate the delivery and anticancer efficacy of various drugs. DNA nanostructures have been considered one of the most promising nanocarriers. In the present study, we report a DNA framework-based intelligent DNA nanorobot for selective lysosomal degradation of tumor-specific proteins on cancer cells. We site-specifically anchored an anti-HER2 aptamer (HApt) on a tetrahedral framework nucleic acid (tFNA). This DNA nanorobot (HApt-tFNA) could target HER2-positive breast cancer cells and specifically induce the lysosomal degradation of the membrane protein HER2. An injection of the DNA nanorobot into a mouse model revealed that the presence of tFNA enhanced the stability and prolonged the blood circulation time of HApt, and HApt-tFNA could therefore drive HER2 into lysosomal degradation with a higher efficiency. The formation of the HER2-HApt-tFNA complexes resulted in the HER2-mediated endocytosis and digestion in lysosomes, which effectively reduced the amount of HER2 on the cell surfaces. An increased HER2 digestion through HApt-tFNA further induced cell apoptosis and arrested cell growth. Hence, this novel DNA nanorobot sheds new light on targeted protein degradation for precision breast cancer therapy.

Amplification of USP13 drives non-small cell lung cancer progression mediated by AKT/MAPK signaling

USP13 is emerging as a potential target in cancer therapy. However, the effect of USP13 on tumor progression is controversial. Here we focused on non-small cell lung cancer (NSCLC), a common cancer with high mortality, and studied the role of USP13 in tumor growth. By analysis of multi-level genetic database, we found USP13 is high expressed in heart among healthy primary tissues and is most amplified in lung cancer. Clinical samples of NSCLC showed tumor exhibited high USP13 level compared with adjacent normal tissues. We further utilized lung adenocarcinoma A549 and squamous carcinoma H226 cells as cell model and investigated USP13 effect by USP13 knockdown. As a results, downregulation of USP13 dramatically inhibited A549 and H226 cell proliferation by AKT/MAPK signaling and suppressed tumor growth in nude mice. Collectively, we identified USP13 as a tumor promoter in NSCLC and provide a promising target in cancer therapy.

Mitochondrial DNA copy number instability in ERBB2-amplified breast cancer tumors

Increase in the copy number of ERBB2, a Tyrosine Kinase Receptor (TKR) leads to the overexpression of oncogene product and consequently uncontrolled cell proliferation which has been reported in different aggressive cancers with mitochondrial malfunctions. Although, amplification of ERBB2 has been reported in different studies; however, the association between changes in mitochondrial DNA content and the ERBB2 gene copy number is poorly understood. The relative mitochondrial DNA content of breast cancer tumor tissues of 70 patients who were referred to Imam Khomeini Hospital Complex was determined using quantitative Real-time PCR. Multiplex ligation-dependent probe amplification (MLPA) was conducted to evaluate the ERBB2 gene copy number variation and finally, two-sample Wilcoxon rank-sum (Mann-Whitney) test was used to investigate the possible association between mitochondrial DNA (mtDNA) content and the ERBB2 gene amplification. Seventeen out of 70 breast cancer tumor tissues were found with ERBB2 gene amplification. Comparison of the mitochondrial DNA content of the aforementioned samples with the rest of the cases showed a significant decrease in the mitochondrial DNA content of the ERBB2-amplified samples (P=0.01). Our data provided evidence that ERBB2 have the potential to have a regulatory role over mitochondrial activity by controlling the mtDNA content.

Mitochondrial determinants of cancer health disparities

Mitochondria, which are multi-functional, have been implicated in cancer initiation, progression, and metastasis due to metabolic alterations in transformed cells. Mitochondria are involved in the generation of energy, cell growth and differentiation, cellular signaling, cell cycle control, and cell death. To date, the mitochondrial basis of cancer disparities is unknown. The goal of this review is to provide an understanding and a framework of mitochondrial determinants that may contribute to cancer disparities in racially different populations. Due to maternal inheritance and ethnic-based diversity, the mitochondrial genome (mtDNA) contributes to inherited racial disparities. In people of African ancestry, several germline, population-specific haplotype variants in mtDNA as well as depletion of mtDNA have been linked to cancer predisposition and cancer disparities. Indeed, depletion of mtDNA and mutations in mtDNA or nuclear genome (nDNA)-encoded mitochondrial proteins lead to mitochondrial dysfunction and promote resistance to apoptosis, the epithelial-to-mesenchymal transition, and metastatic disease, all of which can contribute to cancer disparity and tumor aggressiveness related to racial disparities. Ethnic differences at the level of expression or genetic variations in nDNA encoding the mitochondrial proteome, including mitochondria-localized mtDNA replication and repair proteins, miRNA, transcription factors, kinases and phosphatases, and tumor suppressors and oncogenes may underlie susceptibility to high-risk and aggressive cancers found in African population and other ethnicities. The mitochondrial retrograde signaling that alters the expression profile of nuclear genes in response to dysfunctional mitochondria is a mechanism for tumorigenesis. In ethnic populations, differences in mitochondrial function may alter the cross talk between mitochondria and the nucleus at epigenetic and genetic levels, which can also contribute to cancer health disparities. Targeting mitochondrial determinants and mitochondrial retrograde signaling could provide a promising strategy for the development of selective anticancer therapy for dealing with cancer disparities. Further, agents that restore mitochondrial function to optimal levels should permit sensitivity to anticancer agents for the treatment of aggressive tumors that occur in racially diverse populations and hence help in reducing racial disparities.

Carnosic Acid Suppresses the H2O2-Induced Mitochondria-Related Bioenergetics Disturbances and Redox Impairment in SH-SY5Y Cells: Role for Nrf2

The phenolic diterpene carnosic acid (CA, C₂₀H₂₈O₄) exerts antioxidant, anti-inflammatory, anti-apoptotic, and anti-cancer effects in mammalian cells. CA activates the nuclear factor erythroid 2-related factor 2 (Nrf2), among other signaling pathways, and restores cell viability in several in vitro and in vivo experimental models. We have previously reported that CA affords mitochondrial protection against various chemical challenges. However, it was not clear yet whether CA would prevent chemically induced impairment of the tricarboxylic acid cycle (TCA) function in mammalian cells. In the present work, we found that a pretreatment of human neuroblastoma SH-SY5Y cells with CA at 1 μM for 12 h prevented the hydrogen peroxide (H₂O₂)-induced impairment of the TCA enzymes (aconitase, α-ketoglutarate dehydrogenase (α-KGDH), succinate dehydrogenase (SDH)) and abolished the inhibition of the complexes I and V and restored the levels of ATP by a mechanism associated with Nrf2. CA also exhibited antioxidant abilities by enhancing the levels of reduced glutathione (GSH) and decreasing the content oxidative stress markers (cellular 8-oxo-2'-deoxyguanosine (8-oxo-dG), and mitochondrial malondialdehyde (MDA), protein carbonyl, and 3-nitrotyrosine). Silencing of Nrf2 by small interfering RNA (siRNA) abrogated the protective effects elicited by CA in mitochondria of SH-SY5Y cells. Therefore, CA prevented the H₂O₂-triggered mitochondrial impairment by an Nrf2-dependent mechanism. The specific role of Nrf2 in ameliorating the function of TCA enzymes function needs further research.

Selective Disruption of Respiratory Supercomplexes as a New Strategy to Suppress Her2high Breast Cancer

AIMS

Expression of the HER2 oncogene in breast cancer is associated with resistance to treatment, and Her2 may regulate bioenergetics. Therefore, we investigated whether disruption of the electron transport chain (ETC) is a viable strategy to eliminate Her2^high disease.

RESULTS

We demonstrate that Her2^high cells and tumors have increased assembly of respiratory supercomplexes (SCs) and increased complex I-driven respiration in vitro and in vivo. They are also highly sensitive to MitoTam, a novel mitochondrial-targeted derivative of tamoxifen. Unlike tamoxifen, MitoTam efficiently suppresses experimental Her2^high tumors without systemic toxicity. Mechanistically, MitoTam inhibits complex I-driven respiration and disrupts respiratory SCs in Her2^high background in vitro and in vivo, leading to elevated reactive oxygen species production and cell death. Intriguingly, higher sensitivity of Her2^high cells to MitoTam is dependent on the mitochondrial fraction of Her2.

INNOVATION

Oncogenes such as HER2 can restructure ETC, creating a previously unrecognized therapeutic vulnerability exploitable by SC-disrupting agents such as MitoTam.

CONCLUSION

We propose that the ETC is a suitable therapeutic target in Her2^high disease. Antioxid. Redox Signal. 26, 84-103.