SOX2 Expression Does Not Guarantee Cancer Stem Cell-like Characteristics in Lung Adenocarcinoma.

Effectively targeting cancer stemness is essential for successful cancer therapy. Recent studies have revealed that SOX2, a pluripotent stem cell factor, significantly contributes to cancer stem cell (CSC)-like characteristics closely associated with cancer malignancy. However, its contradictory impact on patient survival in specific cancer types, including lung adenocarcinoma (LUAD), underscores the need for more comprehensive research to clarify its functional effect on cancer stemness. In this study, we demonstrate that SOX2 is not universally required for the regulation of CSC-like properties in LUAD. We generated SOX2 knockouts in A549, H358, and HCC827 LUAD cells using the CRISPR/Cas9 system. Our results reveal unchanged CSC characteristics, including sustained proliferation, tumor sphere formation, invasion, migration, and therapy resistance, compared to normal cells. Conversely, SOX2 knockdown using conditional shRNA targeting SOX2, significantly reduced CSC traits. However, these loss-of-function effects were not rescued by SOX2 resistant to shRNA, underscoring the potential for SOX2 protein level-independent results in prior siRNA- or shRNA-based research. Ultimately, our findings demonstrate that SOX2 is not absolutely essential in LUAD cancer cells. This emphasizes the necessity of considering cancer subtype-dependent and context-dependent factors when targeting SOX2 overexpression as a potential therapeutic vulnerability in diverse cancers.

Casein Kinase 2α Augments Oxaliplatin Resistance in Colorectal Cancer Cells by Increasing ABCE1 Expression.

BACKGROUND/AIM: Antitumor drug resistance is a major hurdle in treating patients with malignant tumors. Casein kinase 2α (CK2α) expression is highly enhanced in oxaliplatin-resistant CRC cells. We investigated whether CK2α expression is associated with oxaliplatin resistance in CRC cells. MATERIALS AND METHODS: To determine the effect of CK2α on drug resistance in CRC, we assessed the cell viability, adenosine triphosphate-binding cassette (ABC) transporter expression, apoptosis, and sphere formation according to CK2α expression in oxaliplatin-resistant CRC cells. RESULTS: CK2α expression was significantly increased in oxaliplatin-resistant CRC cells compared with that in wild-type CRC cells. In addition, the mRNA expression of ABC transporters, including ABCA12, ABCC2, and ABCE1, was significantly enhanced in oxaliplatin-resistant CRC cells, whereas this effect was blocked by the knockdown of CK2α. Furthermore, a cell viability test showed that oxaliplatin resistance was inhibited by decreasing CK2α expression, resulting in the induction of apoptosis and suppression of sphere formation. CONCLUSION: CK2α regulates cell survival, apoptosis, sphere formation, and drug resistance in oxaliplatin-resistant CRC cells by regulating ABC transporters. Therefore, targeting CK2α in drug-resistant CRC cells may be a novel strategy for treating patients with CRC.

Carboxylesterase-overexpressing hTERT-immortalized human adipose stem cells in prostate tumor growth inhibition by irinotecan.

INTRODUCTION: Effective chemotherapy has not yet to be developed for castration-resistant prostate cancer (CRPC). Cell-mediated enzyme prodrug therapy (EPT), including a combination of carboxylesterase (CE) and irinotecan (CPT-11), could be a possible treatment option. This study explored a cell-mediated EPT, including a combination of CE and irinotecan (CPT-11), to inhibit CRPC tumor growth using rabbit CE-overexpressing human TERT-immortalized adipose-derived stem cells (hTERT-ADSC.CE). MATERIALS AND METHODS: An hTERT ADSC.CE cell line was established by transfection with a lentiviral vector (CLV-Ubic) encoding the rabbit CE gene. To determine the in vitro suicide effects of hTERT-ADSC.CE, cell cultures were performed using various concentrations of CPT-11 (0.01-5 µM), and to determine the in vitro cytotoxic effects of hTERT-ADSC.CE cells, PC3 and hTERT-ADSC.CE cells were co-cultured. For the in vivo model, PC3 cells (1 × 106 cells) were injected subcutaneously into the flanks of nude mice and hTERT-ADSC.CE cells were injected via an intracardiac route, followed by the continuous treatment using CPT-11 for 2 weeks. The final change in tumor volume was measured and immunohistochemical analysis was performed. RESULTS: The directional and selective migration of hTERT-ADSC.CE cells toward PC3 cells was significantly stimulated by PC3 cells in vitro. The number of apoptotic PC3 cells significantly increased in the presence of hTERT-ADSC.CE and CPT-11 compared to CPT-11 alone. In the in vivo study, the inhibitory effects of hTERT-ADSC.CE combined with CPT-11 were higher than those of CPT-11 monotherapy. After treatment with CPT-11 alone or ADSC.CE in combination with CPT-11, the removed tumor tissues showed hyperchromatic nuclei and apoptotic bodies. CE-overexpressing ADSCs potentiated the inhibition of tumor growth in CRPC-bearing mice in the presence of CPT-11 prodrugs. CONCLUSIONS: This report suggests that cell-mediated EPT including CE and CPT-11 may be efficacious in treating CRPC.

Carboxyl Esterase-TRAIL Expressing Human Adipose Stem Cells Inhibit Tumor Growth in Castration-Resistant Prostate Cancer-Bearing Mice with Less Toxicity.

It has been proposed that CRPC treatment with reduced systemic toxicity can be achieved by employing genes that express enzymes that activate pharmacological agents. In this paper, we report our study that used human adipose-derived stem cells (ADSC), rabbit CE, and human TRAIL with reduced toxicity to explore how tumor development can be suppressed in CRPC-bearing mouse models. In vitro and in vivo directional migration of ADSC.CE.sTRAIL cells toward PC3 cells was significantly stimulated.ADSC.CE.sTRAIL showed higher suicide effects than did ADSC, ADSC.CE, or ADSC.sTRAIL under CPT-11 treatment. PC3 cells co-cultured with ADSC.CE.TRAIL showed higher cytotoxicity than did CPT-11 monotherapy, ADSC.CE, or ADSC.sTRAIL under CPT-11 treatment. ADSC.CE.sTRAIL showed higher apoptosis than did CPT-11 monotherapy, ADSC.CE, or ADSC.sTRAIL under CPT-11 treatment. In the in vivo study, ADSC.CE.sTRAIL inhibited tumor growth more than did CPT-11 monotherapy, ADSC.CE, or ADSC.sTRAIL under CPT-11 treatment. The evidence suggests that patients' own ADSC could be used in clinical trials for CRPC treatment based on therapeutic stem cells that express CE and TRAIL complex genes.

Inhibitory Effect of Oxaliplatin-loaded Engineered Milk Extracellular Vesicles on Tumor Progression.

BACKGROUND/AIM: Anti-cancer chemotherapy is an effective therapeutic approach. Milk extracellular vesicles (EVs) loaded with chemotherapeutics have a potential anticancer effect by acting as a drug delivery system. Thus, our study aimed to explore the effect of engineered milk extracellular vesicles. MATERIALS AND METHODS: To treat epidermal growth factor receptor (EGFR) expressing solid tumors, we established oxaliplatin-loaded milk EV conjugated with GE11 peptide (GE11Milk EVoxal), which has a high affinity to EGFR and assessed their anti-cancer effect in vitro and in vivo. RESULTS: Drug-loaded GE11Milk EVoxal showed significantly higher incorporation into EGFR expressing cancer cells compared with milk EV without GE11 conjugation (Milk EVoxal), leading to apoptosis of cancer cells. GE11Milk EVoxal also inhibited cell viability compared to milk EVoxal or oxaliplatin alone. In colorectal cancer xenograft murine model, GE11Milk EVoxal showed the maximum therapeutic effect on tumor progression. These findings indicate that GE11Milk EVoxal suppresses EGFR expressing cancer through GE11 peptide-mediated EGFR targeting and subsequently anti-cancer drug delivery. CONCLUSION: Anti-cancer drug-loaded engineered milk EVs might be a novel therapeutic approach for treating patients with EGFR expressing solid tumors.

Exosomes isolated from melatonin-stimulated mesenchymal stem cells improve kidney function by regulating inflammation and fibrosis in a chronic kidney disease mouse model.

Chronic kidney disease (CKD) is defined as structural and functional abnormalities of the kidney due to inflammation and fibrosis. We investigated the therapeutic effects of exosomes secreted by melatonin-stimulated mesenchymal stem cells (Exocue) on the functional recovery of the kidney in a CKD mouse model. Exocue upregulated gene expression of micro RNAs (miRNAs) associated with anti-inflammatory and anti-fibrotic effects. Exocue-treated groups exhibited low tumor necrosis factor-α and transforming growth factor-ß levels in serum and fibrosis inhibition in kidney tissues mediated through regulation of cell apoptosis and proliferation of fibrosis-related cells. Exocue treatment decreased the gene expression of CKD progression-related miRNAs. Moreover, the CKD severity was alleviated in the Exocue group via upregulation of aquaporin 2 and 5 levels and reduction of blood urea nitrogen and creatinine, resulting in functional recovery of the kidney. In conclusion, Exocue could be a novel therapeutic agent for treating CKD by regulating inflammation and fibrosis.

Topical Administration of Melatonin-Loaded Extracellular Vesicle-Mimetic Nanovesicles Improves 2,4-Dinitrofluorobenzene-Induced Atopic Dermatitis.

Atopic dermatitis (AD) is caused by multiple factors that trigger chronic skin inflammation, including a defective skin barrier, immune cell activation, and microbial exposure. Although melatonin has an excellent biosafety profile and a potential to treat AD, there is limited clinical evidence from controlled trials that support the use of melatonin as an AD treatment. The delivery of melatonin via the transdermal delivery system is also a challenge in designing melatonin-based AD treatments. In this study, we generated melatonin-loaded extracellular vesicle-mimetic nanoparticles (MelaNVs) to improve the transdermal delivery of melatonin and to evaluate their therapeutic potential in AD. The MelaNVs were spherical nanoparticles with an average size of 100 nm, which is the optimal size for the transdermal delivery of drugs. MelaNVs showed anti-inflammatory effects by suppressing the release of TNF-α and ß-hexosaminidase in LPS-treated RAW264.7 cells and compound 48/80-treated RBL-2H3 cells, respectively. MelaNVs showed a superior suppressive effect compared to an equivalent concentration of free melatonin. Treating a 2,4-dinitrofluorobenzene (DNCB)-induced AD-like mouse model with MelaNVs improved AD by suppressing local inflammation, mast cell infiltration, and fibrosis. In addition, MelaNVs effectively suppressed serum IgE levels and regulated serum IFN-γ and IL-4 levels. Taken together, these results suggest that MelaNVs are novel and efficient transdermal delivery systems of melatonin and that MelaNVs can be used as a treatment to improve AD.

Correction: Yun et al. Prion Protein of Extracellular Vesicle Regulates the Progression of Colorectal Cancer. Cancers 2021, 13, 2144.

The authors wish to make the following corrections to this paper [...].

Prion Protein of Extracellular Vesicle Regulates the Progression of Colorectal Cancer.

Colorectal cancer (CRC) is one of the leading causes of cancer-related death due to its aggressive metastasis in later stages. Although there is a growing interest in the tumorigenic role of cellular prion protein (PrPC) in the process of metastasis, the precise mechanism behind the cellular communication involving prion proteins remains poorly understood. This study found that hypoxic tumor microenvironment increased the PrPC-expressing exosomes from CRC, and these exosomes regulate the CRC cell behavior and tumor progression depending on the expression of PrPC. Hypoxic exosomes from CRC cells promoted sphere formation, the expression of tumor-inducing genes, migration, invasion, and tumor growth. Furthermore, these exosomes increased endothelial permeability, migration, invasion, and angiogenic cytokine secretion. These effects were associated with PrPC expression. Application of anti-PrPC antibody with 5-fluorouracil significantly suppressed the CRC progression in a murine xenograft model. Taken together, these findings indicate that PrP-expressing exosomes secreted by hypoxic CRC cells are a key factor in the tumorigenic CRC-to-CRC and CRC-to-endothelial cell communication. Significance: These findings suggest that inhibiting PrPC in hypoxic exosomes during chemotherapy may be an effective therapeutic strategy in colorectal cancer.

The Dual Role of Autophagy in Cancer Development and a Therapeutic Strategy for Cancer by Targeting Autophagy.

Autophagy is a delicate intracellular degradation process that occurs due to diverse stressful conditions, including the accumulation of damaged proteins and organelles as well as nutrient deprivation. The mechanism of autophagy is initiated by the creation of autophagosomes, which capture and encapsulate abnormal components. Afterward, autophagosomes assemble with lysosomes to recycle or remove degradative cargo. The regulation of autophagy has bipolar roles in cancer suppression and promotion in diverse cancers. Furthermore, autophagy modulates the features of tumorigenesis, cancer metastasis, cancer stem cells, and drug resistance against anticancer agents. Some autophagy regulators are used to modulate autophagy for anticancer therapy but the dual roles of autophagy limit their application in anticancer therapy, and present as the main reason for therapy failure. In this review, we summarize the mechanisms of autophagy, tumorigenesis, metastasis, cancer stem cells, and resistance against anticancer agents. Finally, we discuss whether targeting autophagy is a promising and effective therapeutic strategy in anticancer therapy.

Knockdown of CK2α reduces P-cresol-induced fibrosis in human renal proximal tubule epithelial cells via the downregulation of profilin-1.

Renal fibrosis is one of the main causes of chronic kidney disease. Many studies have focused on fibroblasts and myofibroblasts involved in renal fibrogenesis. Recently, several studies have reported that renal proximal tubule epithelial cells are possible initiators of renal fibrosis. However, the mechanism through which cells induce renal fibrosis is poorly understood. In this study, we found that CK2α induces fibrosis in renal proximal tubule epithelial cells (TH1) by regulating the expression of profilin-1 (Pfn1). CKD mouse model and TH1 cells treated with P-cresol also showed an increased level of Pfn1. The knockdown of CK2α suppressed fibrosis in TH1 cells via the downregulation of Pfn1. In particular, CK2α knockdown inhibited the expression of stress fibers and fibrosis-related proteins in P-cresol-treated TH1 cells. Furthermore, the knockdown of CK2α inhibited mitochondrial dysfunction and restored cellular senescence and cell cycle in P-cresol-treated TH1 cells. These results indicate that CK2α induces renal fibrosis through Pfn1, which makes CK2α a key target molecule in the treatment of fibrosis related to chronic kidney disease.

Role of PrPC in Cancer Stem Cell Characteristics and Drug Resistance in Colon Cancer Cells.

BACKGROUND/AIM: Cancer stem cell characteristics and drug resistance of colorectal cancer are associated with failure of cancer treatment. In this study, we investigated the effects of PrPC on cancer stem cell characteristics, migration, invasion, and drug resistance of 5FU-resistant CRC cells. MATERIALS AND METHODS: PrPC negative and PrPC positive cells were isolated from 5FU-resistant CRC cells using magnetic activated cell sorting. Sphere formation, cancer stem cell marker expression, migration, invasion, and drug resistance were analyzed. RESULTS: PrPC positive cells showed increased sphere formation capacity and increased expression of cancer stem cell markers compared to PrPC negative cells. In addition, PrPC positive cells showed increased migration, invasion and drug resistance compared to PrPC negative cells. Furthermore, knockdown of PrPC abolished these effects. CONCLUSION: PrPC expression is important in CRC cell behavior, such as sphere formation, migration, invasion, and drug resistance. PrPC is an important therapeutic target for the treatment of CRC.

Melatonin Suppresses Renal Cortical Fibrosis by Inhibiting Cytoskeleton Reorganization and Mitochondrial Dysfunction through Regulation of miR-4516.

Renal fibrosis, a major risk factor for kidney failure, can lead to chronic kidney disease (CKD) and is caused by cytoskeleton reorganization and mitochondrial dysfunction. In this study, we investigated the potential of melatonin treatment to reduce renal fibrosis by recovering the cytoskeleton reorganization and mitochondrial dysfunction. We found that miR-4516 expression was downregulated in the renal cortex of CKD mice and P-cresol-treated TH1 cells. Decreased miR-4516 expression stimulated cytoskeleton reorganization and mitochondrial dysfunction, and induced renal fibrosis. Melatonin treatment suppressed fibrosis by inhibiting cytoskeleton reorganization and restoring mitochondrial function via increased miR-4516 expression. More specifically, melatonin treatment increased miR-4516 expression while decreasing ITGA9 expression, thereby inhibiting cytoskeleton reorganization. In addition, increased expression of miR-4516 by melatonin treatment reduced ROS formation and restored mitochondrial function. These findings suggest that melatonin may be a promising treatment for patients with CKD having renal fibrosis. Moreover, regulation of miR-4516 expression may be a novel strategy for the treatment of renal fibrosis.

Heat Shock Proteins: Agents of Cancer Development and Therapeutic Targets in Anti-Cancer Therapy.

Heat shock proteins (HSPs) constitute a large family of molecular chaperones classified by their molecular weights, and they include HSP27, HSP40, HSP60, HSP70, and HSP90. HSPs function in diverse physiological and protective processes to assist in maintaining cellular homeostasis. In particular, HSPs participate in protein folding and maturation processes under diverse stressors such as heat shock, hypoxia, and degradation. Notably, HSPs also play essential roles across cancers as they are implicated in a variety of cancer-related activities such as cell proliferation, metastasis, and anti-cancer drug resistance. In this review, we comprehensively discuss the functions of HSPs in association with cancer initiation, progression, and metastasis and anti-cancer therapy resistance. Moreover, the potential utilization of HSPs to enhance the effects of chemo-, radio-, and immunotherapy is explored. Taken together, HSPs have multiple clinical usages as biomarkers for cancer diagnosis and prognosis as well as the potential therapeutic targets for anti-cancer treatment.

Therapeutic Application of Diverse Marine-derived Natural Products in Cancer Therapy.

Natural products (NPs) are useful sources of bioactive compounds and play important roles in the development and discovery of new drugs for diverse human diseases. Most natural products originate from terrestrial species, but diverse marine organisms are another source of new agents for cancer therapy. Natural products derived from marine organisms show diverse pharmacological activities via bioactive secondary metabolites. They regulate biological activities, such as cell proliferation, cell viability, induction of ROS production, ER stress, and apoptosis via modulation of cellular mechanisms in many cancers. Many natural products isolated from marine species require further study to elucidate the efficacy of their biological activity and anticancer effects. In this review, we summarize the biological properties and anticancer effects of diverse natural products extracted from marine organisms and their roles in tumor therapy.

Hypoxia-induced PGC-1α Regulates Mitochondrial Function and Tumorigenesis of Colorectal Cancer Cells.

BACKGROUND/AIM: Hypoxia promotes tumor proliferation and metastasis in colorectal cancer (CRC). Since the tumor microenvironment is generally characterized by hypoxia, its understanding is important for cancer therapy. We hypothesized that hypoxia promotes the mitochondrial function, mobility, and proliferation of CRC by up-regulating peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α). MATERIALS AND METHODS: To assess the effects of PGC-1α under hypoxia, we investigated the mitochondrial function, cell motility, and sphere formation as well as proliferation and apoptosis of CRC. RESULTS: Under hypoxia, we confirmed the increased expression of PGC-1α and reduced production of reactive oxygen species (ROS) by activating anti-oxidant enzymes. Also, up-regulation of PGC-1α enhanced the motility, sphere formation, and proliferation of CRC. Under the presence of the anti-cancer drug 5-fluorouracil (5FU), up-regulation of PGC-1α under hypoxia promoted resistance of CRC against 5FU-induced apoptosis. CONCLUSION: Targeting PGC-1α could to be a powerful strategy for CRC therapy.

Pioglitazone Improves the Function of Human Mesenchymal Stem Cells in Chronic Kidney Disease Patients.

Mesenchymal stem cells (MSCs) are optimal sources of autologous stem cells for cell-based therapy in chronic kidney disease (CKD). However, CKD-associated pathophysiological conditions, such as endoplasmic reticulum (ER) stress and oxidative stress, decrease MSC function. In this work, we study the protective effect of pioglitazone on MSCs isolated from CKD patients (CKD-MSCs) against CKD-induced ER stress. In CKD-MSCs, ER stress is found to induce mitochondrial reactive oxygen species generation and mitochondrial dysfunction. Treatment with pioglitazone reduces the expression of ER stress markers and mitochondrial fusion proteins. Pioglitazone increases the expression of cellular prion protein (PrPC) in CKD-MSCs, which is dependent on the expression levels of proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α). Treatment with pioglitazone is found to protect CKD-MSCs against reactive oxygen species generation, aberrant mitochondrial oxidative phosphorylation of complexes I and IV, and aberrant proliferation capacity through the PGC-1α-PrPC axis. These results indicate that pioglitazone protects the mitochondria of MSCs from CKD-induced ER stress. Pioglitazone treatment of CKD-MSCs may be a potential therapeutic strategy for CKD patients.

PGC-1α Controls Mitochondrial Biogenesis in Drug-Resistant Colorectal Cancer Cells by Regulating Endoplasmic Reticulum Stress.

Anti-cancer drug resistance is a serious issue for patients with colorectal cancer (CRC). Although recent studies have shown the mechanism by which CRC cells become drug resistant, novel strategies for overcoming this drug resistance have not yet been developed. To address this problem, we characterized 5-fluorouracil (5FU)-resistant CRC cells after treatment with 5FU, and focused on the expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) in these cells. In 5FU-resistant CRC cells, the 5FU did not considerably decrease the mitochondrial biogenesis or mitochondrial complex I and IV activities, and only partially decreased the antioxidant enzymatic activity, oxygen consumption ratio, and cell survival. The expression of PGC-1α was remarkably increased in the 5FU-resistant CRC cells compared with the 5FU-sensitive CRC cells. The 5FU-resistant CRC cells displayed enhanced mitochondrial biogenesis, oxidative phosphorylation, and antioxidant enzyme activities against 5FU-induced reactive oxygen species, because of the increased expression of PGC-1α. PGC-1α inhibited 5FU-induced endoplasmic reticulum (ER) stress in the 5FU-resistant CRC cells, resulting in the suppression of apoptosis. These findings reveal that PGC-1α plays an important role in drug resistance in 5FU-resistant CRC cells. Moreover, PGC-1α could serve as a novel target in patients with 5FU-resistant CRC.

Potential and Therapeutic Efficacy of Cell-based Therapy Using Mesenchymal Stem Cells for Acute/chronic Kidney Disease.

Kidney disease can be either acute kidney injury (AKI) or chronic kidney disease (CKD) and it can lead to the development of functional organ failure. Mesenchymal stem cells (MSCs) are derived from a diverse range of human tissues. They are multipotent and have immunomodulatory effects to assist in the recovery from tissue injury and the inhibition of inflammation. Numerous studies have investigated the feasibility, safety, and efficacy of MSC-based therapies for kidney disease. Although the exact mechanism of MSC-based therapy remains uncertain, their therapeutic value in the treatment of a diverse range of kidney diseases has been studied in clinical trials. The use of MSCs is a promising therapeutic strategy for both acute and chronic kidney disease. The mechanism underlying the effects of MSCs on survival rate after transplantation and functional repair of damaged tissue is still ambiguous. The paracrine effects of MSCs on renal recovery, optimization of the microenvironment for cell survival, and control of inflammatory responses are thought to be related to their interaction with the damaged kidney environment. This review discusses recent experimental and clinical findings related to kidney disease, with a focus on the role of MSCs in kidney disease recovery, differentiation, and microenvironment. The therapeutic efficacy and current applications of MSC-based kidney disease therapies are also discussed.