MiTF is Associated with Chemoresistance to Cisplatin in A549 Lung Cancer Cells via Modulating Lysosomal Biogenesis and Autophagy

MITF regulates the subcellular location of HIF1α through SUMOylation to promote the invasion and metastasis of daughter cells derived from polyploid giant cancer cells

High concentrations of cobalt chloride (CoCl2) can induce the formation of polyploid giant cancer cells (PGCCs) in various tumors, which can produce daughter cells with strong proliferative, migratory and invasive abilities via asymmetric division. To study the role of hypoxia‑inducible factor (HIF) 1α in the formation of PGCCs, colon cancer cell lines Hct116 and LoVo were used as experimental subjects. Western blotting, nuclear and cytoplasmic protein extraction and immunocytochemical experiments were used to compare the changes in the expression and subcellular localization of HIF1α, microphthalmia‑associated transcription factor (MITF), protein inhibitor of activated STAT protein 4 (PIAS4) and von Hippel‑Lindau disease tumor suppressor (VHL) after treatment with CoCl2. The SUMOylation of HIFα was verified by co‑immunoprecipitation assay. After inhibiting HIF1α SUMOylation, the changes in proliferation, migration and invasion abilities of Hct116 and LoVo were compared by plate colony formation, wound healing and Transwell migration and invasion. In addition, lysine sites that led to SUMOylation of HIF1α were identified through site mutation experiments. The results showed that CoCl2 can induce the formation of PGCCs with the expression level of HIF1α higher in treated cells than in control cells. HIF1α was primarily located in the cytoplasm of control cell. Following CoCl2 treatment, the subcellular localization of HIF1α was primarily in the nuclei of PGCCs with daughter cells (PDCs). After treatment with SUMOylation inhibitors, the nuclear HIF1α expression in PDCs decreased. Furthermore, their proliferation, migration and invasion abilities also decreased. After inhibiting the expression of MITF, the expression of HIF1α decreased. MITF can regulate HIF1α SUMOylation. Expression and subcellular localization of VHL and HIF1α did not change following PIAS4 knockdown. SUMOylation of HIF1α occurs at the amino acid sites K391 and K477 in PDCs. After mutation of the two sites, nuclear expression of HIF1α in PDCs was reduced, along with a significant reduction in the proliferation, migration and invasion abilities. In conclusion, the post‑translation modification regulated the subcellular location of HIF1α and the nuclear expression of HIF1α promoted the proliferation, migration and invasion abilities of PDCs. MITF could regulate the transcription and protein levels of HIF1α and participate in the regulation of HIF1α SUMOylation.

Autophagy-driven regulation of cisplatin response in human cancers: Exploring molecular and cell death dynamics

Despite the challenges posed by drug resistance and side effects, chemotherapy remains a pivotal strategy in cancer treatment. A key issue in this context is macroautophagy (commonly known as autophagy), a dysregulated cell death mechanism often observed during chemotherapy. Autophagy plays a cytoprotective role by maintaining cellular homeostasis and recycling organelles, and emerging evidence points to its significant role in promoting cancer progression. Cisplatin, a DNA-intercalating agent known for inducing cell death and cell cycle arrest, often encounters resistance in chemotherapy treatments. Recent studies have shown that autophagy can contribute to cisplatin resistance or insensitivity in tumor cells through various mechanisms. This resistance can be mediated by protective autophagy, which suppresses apoptosis. Additionally, autophagy-related changes in tumor cell metastasis, particularly the induction of Epithelial-Mesenchymal Transition (EMT), can also lead to cisplatin resistance. Nevertheless, pharmacological strategies targeting the regulation of autophagy and apoptosis offer promising avenues to enhance cisplatin sensitivity in cancer therapy. Notably, numerous non-coding RNAs have been identified as regulators of autophagy in the context of cisplatin chemotherapy. Thus, therapeutic targeting of autophagy or its associated pathways holds potential for restoring cisplatin sensitivity, highlighting an important direction for future clinical research.

Nano-hydroxyapatite structures for bone regenerative medicine: Cell-material interaction

Bone tissue engineering holds great promise for the regeneration of damaged or severe bone defects. However, several challenges hinder its translation into clinical practice. To address these challenges, interdisciplinary efforts and advances in biomaterials, cell biology, and bioengineering are required. In recent years, nano-hydroxyapatite (nHA)-based scaffolds have emerged as a promising approach for the development of bone regenerative agents. The unique similarity of nHA with minerals found in natural bones promotes remineralization and stimulates bone growth, which are crucial factors for efficient bone regeneration. Moreover, nHA exhibits desirable properties, such as strong chemical interactions with bone and facilitation of tissue growth, without inducing inflammation or toxicity. It also promotes osteoblast survival, adhesion, and proliferation, as well as increasing alkaline phosphatase activity, osteogenic differentiation, and bone-specific gene expression. However, it is important to note that the effect of nHA on osteoblast behavior is dose-dependent, with cytotoxic effects observed at higher doses. Additionally, the particle size of nHA plays a crucial role, with smaller particles having a more significant impact. Therefore, in this review, we highlighted the potential of nHA for improving bone regeneration processes and summarized the available data on bone cell response to nHA-based scaffolds. In addition, an attempt is made to portray the current status of bone tissue engineering using nHA/polymer hybrids and some recent scientific research in the field.

Autophagy and cancer drug resistance in dialogue: Pre-clinical and clinical evidence

The emergence of drug resistance is a major challenge for oncologists. Resistance can be categorized as acquired or intrinsic; the alteration of several biological mechanisms contributes to both intrinsic and acquired resistance. Macroautophagy/autophagy is the primary process in eukaryotes for the degradation of macromolecules and organelles. This process is critical in maintaining cellular homeostasis. Given its function as either a pro-survival or a pro-death phenomenon, autophagy has a complex physio-pathological role. In some circumstances, autophagy can confer chemoresistance and promote cell survival, whereas in others it can promote chemosensitivity and contribute to cell death. The role of autophagy in the modulation of cancer drug resistance reflects its impact on apoptosis and metastasis. The regulation of autophagy in cancer is mediated by various factors including AMP-activated protein kinase (AMPK), MAPK, phosphoinositide 3-kinase (PI3K)-AKT, BECN1 and ATG proteins. Non-coding RNAs are among the main regulators of autophagy, e.g., via the modulation of chemoresistance pathways. Due to the significant contribution of autophagy in cancer drug resistance, small molecule modulators and natural compounds targeting autophagy have been introduced to alter the response of cancer cells to chemotherapy. Furthermore, nanotherapeutic approaches based on autophagy regulation have been introduced in pre-clinical cancer therapy. In this review we consider the potential for using autophagy regulators for the clinical treatment of malignancies.

A new glance at autophagolysosomal-dependent or -independent function of transcriptional factor EB in human cancer

Autophagy-lysosome system plays a variety of roles in human cancers. In addition to being implicated in metabolism, it is also involved in tumor immunity, remodeling the tumor microenvironment, vascular proliferation, and promoting tumor progression and metastasis. Transcriptional factor EB (TFEB) is a major regulator of the autophagy-lysosomal system. With the in-depth studies on TFEB, researchers have found that it promotes various cancer phenotypes by regulating the autophagolysosomal system, and even in an autophagy-independent way. In this review, we summarize the recent findings about TFEB in various types of cancer (melanoma, pancreatic ductal adenocarcinoma, renal cell carcinoma, colorectal cancer, breast cancer, prostate cancer, ovarian cancer and lung cancer), and shed some light on the mechanisms by which it may serve as a potential target for cancer treatment.

FIR-preconditioning promotes Akt-mTOR-exosome manufacture in cooperation with MITF to boost resilience of rat bone marrow-derived stem cells

A previous study from our laboratory observed the protective effects of far-infrared irradiation (FIR) on bone marrow-derived stem cells (BMSCs) against oxidative stress. However, it remains unknown precisely how FIR influences BMSC survival. We identify an unexpected route among the expression of MITF, BCL2, mTOR, and exosome in FIR-preconditioned BMSCs. MITF siRNA demonstrated that loss of MITF expression not only inhibited cell proliferation but also reduced the FIR-mediated expression of mTOR, BCL2, and exosome. mTOR signaling pathways have been implicated in cell growth, proliferation, and survival. We also found that rapamycin, a potent and selective inhibitor of mTOR, when combined with MITF siRNA, repressed FIR-mediated CD63 and BCL2 expression. In addition, FIR-preconditioned BMSCs demonstrated more tolerance in multiple stressful environments than untreated BMSCs. The elevated exosomes in conditioned medium derived from FIR-preconditioned BMSCs also repaired H9c2 cells that sustained cellular damage after subjected to an array of environmental stress conditions. Taken together, these results reveal a possible mechanism about how FIR-preconditioned BMSCs and its conditioned media could contribute to cellular resilience during environmental changes via MITF-Akt-mTOR associated with exosome manufacture. FIR preconditioning could thus complement and improve therapeutic applications of BMSCs on outcomes of various disorders.

Insight into autophagy in platinum resistance of cancer

Platinum drugs, as a class of widely used chemotherapy agents, frequently appear in the treatment of cancer at different phrases. However, platinum resistance is the major bottleneck of platinum drugs for exerting anti-tumor effect. At present, the mechanism of platinum resistance has been thoroughly explored in terms of drug delivery methods, DNA damage repair function, etc., but it has not yet been translated into an effective weapon for reversing platinum resistance. Recently, autophagy has been proved to be closely related to platinum resistance, and the involved molecular mechanism may provide a new perspective on platinum resistance. The aim of this review is to sort out the studies related to autophagy and platinum resistance, and to focus on summarizing the relevant molecular mechanisms, so as to provide clues for future studies related to autophagy and platinum resistance.

MITF Downregulation Induces Death in Human Mast Cell Leukemia Cells and Impairs IgE-Dependent Degranulation

Activating mutations in KIT (CD117) have been associated with several diseases, including gastrointestinal stromal tumors and mastocytosis. Rapidly progressing pathologies or drug resistance highlight the need for alternative treatment strategies. Previously, we reported that the adaptor molecule SH3 binding protein 2 (SH3BP2 or 3BP2) regulates KIT expression at the transcriptional level and microphthalmia-associated transcription factor (MITF) expression at the post-transcriptional level in human mast cells and gastrointestinal stromal tumor (GIST) cell lines. Lately, we have found that the SH3BP2 pathway regulates MITF through miR-1246 and miR-5100 in GIST. In this study, miR-1246 and miR-5100 were validated by qPCR in the SH3BP2-silenced human mast cell leukemia cell line (HMC-1). MiRNA overexpression reduces MITF and MITF-dependent target expression in HMC-1. The same pattern was observed after MITF silencing. In addition, MITF inhibitor ML329 treatment reduces MITF expression and affects the viability and cell cycle progression in HMC-1. We also examine whether MITF downregulation affected IgE-dependent mast cell degranulation. MiRNA overexpression, MITF silencing, and ML329 treatment reduced IgE-dependent degranulation in LAD2- and CD34⁺-derived mast cells. These findings suggest MITF may be a potential therapeutic target for allergic reactions and deregulated KIT mast-cell-mediated disorders.

CRISPR-based DNA methylation editing of NNT rescues the cisplatin resistance of lung cancer cells by reducing autophagy

Cisplatin is recommended as a first-line chemotherapeutic agent against advanced non-small cell lung cancer (NSCLC), but acquired resistance substantially limits its clinical efficacy. Recently, DNA methylation has been identified as an essential contributor to chemoresistance. However, the precise DNA methylation regulatory mechanism of cisplatin resistance remains unclear. Here, we found that nicotinamide nucleotide transhydrogenase (NNT) was silenced by DNA hypermethylation in cisplatin resistance A549 (A549/DDP) cells. Also, the DNA hypermethylation of NNT was positively correlated to poor prognosis in NSCLC patients. Overexpression of NNT in A549/DDP cells could reduce their cisplatin resistance, and also suppressed their tumor malignancy such as cell proliferation and clone formation. However, NNT enhanced sensitivity of A549/DDP cells to cisplatin had little to do with its function in mediating NADPH and ROS level, but was mainly because NNT could inhibit protective autophagy in A549/DDP cells. Further investigation revealed that NNT could decrease NAD⁺ level, thereby inactivate SIRT1 and block the autophagy pathway, while re-activation of SIRT1 through NAD⁺ precursor supplementation could antagonize this effect. In addition, targeted demethylation of NNT CpG island via CRISPR/dCas9-Tet1 system significantly reduced its DNA methylation level and inhibited the autophagy and cisplatin resistance in A549/DDP cells. Thus, our study found a novel chemoresistance target gene NNT, which played important roles in cisplatin resistance of lung cancer cells. Our findings also suggested that CRISPR-based DNA methylation editing of NNT could be a potential therapeutics method in cisplatin resistance of lung cancer.

Essential role for STAT3/FOXM1/ATG7 signaling-dependent autophagy in resistance to Icotinib

BACKGROUND

The contribution of autophagy to cancer therapy resistance remains complex, mainly owing to the discrepancy of autophagy mechanisms in different therapy. However, the potential mechanisms of autophagy-mediated resistance to icotinib have yet to be elucidated.

METHODS

The effect of autophagy in icotinib resistance was examined using a series of in vitro and in vivo assays. The results above were further verified in biopsy specimens of lung cancer patients before and after icotinib or gefitinib treatment.

RESULTS

Icotinib increased ATG3, ATG5, and ATG7 expression, but without affecting Beclin-1, VPS34 and ATBG14 levels in icotinib-resistant lung cancer cells. Autophagy blockade by 3-MA or silencing Beclin-1 had no effects on resistance to icotinib. CQ effectively restored lung cancer cell sensitivity to icotinib in vitro and in vivo. Notably, aberrantly activated STAT3 and highly expressed FOXM1 were required for autophagy induced by icotinib, without the involvement of AMPK/mTOR pathway in this process. Alterations of STAT3 activity using genetic and/or pharmacological methods effectively affected FOXM1 and ATG7 levels increased by icotinib, with altering autophagy and icotinib-mediated apoptosis in resistant cells. Furthermore, silencing FOXM1 impaired up-regulated ATG7 induced by STAT3-CA and icotinib. STAT3/FOXM1 signalling blockade also reversed resistance to icotinib in vivo. Finally, we found a negative correlation between STAT3/FOXM1/ATG7 signalling activity and epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) treatment efficacy in patients undergoing EGFR-TKIs treatment.

CONCLUSIONS

Our findings support that STAT3/FOXM1/ATG7 signalling-induced autophagy is a novel mechanism of resistance to icotinib, and provide insights into potential clinical values of ATG7-dependent autophagy in icotinib treatment.

CD44+ and CD133+ Non-Small Cell Lung Cancer Cells Exhibit DNA Damage Response Pathways and Dormant Polyploid Giant Cancer Cell Enrichment Relating to Their p53 Status

Cancer stem cells (CSCs) play a critical role in the initiation, progression and therapy relapse of many cancers including non-small cell lung cancer (NSCLC). Here, we aimed to address the question of whether the FACS-sorted CSC-like (CD44 + &CD133 +) vs. non-CSC (CD44-/CD133- isogenic subpopulations of p53wt A549 and p53null H1299 cells differ in terms of DNA-damage signaling and the appearance of "dormant" features, including polyploidy, which are early markers (predictors) of their sensitivity to genotoxic stress. X-ray irradiation (IR) at 5 Gy provoked significantly higher levels of the ATR-Chk1/Chk2-pathway activity in CD44-/CD133- and CD133+ subpopulations of H1299 cells compared to the respective subpopulations of A549 cells, which only excited ATR-Chk2 activation as demonstrated by the Multiplex DNA-Damage/Genotoxicity profiling. The CD44+ subpopulations did not demonstrate IR-induced activation of ATR, while significantly augmenting only Chk2 and Chk1/2 in the A549- and H1299-derived cells, respectively. Compared to the A549 cells, all the subpopulations of H1299 cells established an increased IR-induced expression of the γH2AX DNA-repair protein. The CD44-/CD133- and CD133+ subpopulations of the A549 cells revealed IR-induced activation of ATR-p53-p21 cell dormancy signaling-mediated pathway, while none of the CD44+ subpopulations of either cell line possessed any signs of such activity. Our data indicated, for the first time, the transcription factor MITF-FAM3C axis operative in p53-deficient H1299 cells, specifically their CD44+ and CD133+ populations, in response to IR, which warrants further investigation. The p21-mediated quiescence is likely the predominant surviving pathway in CD44-/CD133- and CD133+ populations of A549 cells as indicated by single-cell high-content imaging and analysis of Ki67- and EdU-coupled fluorescence after IR stress. SA-beta-galhistology revealed that cellular-stress-induced premature senescence (SIPS) likely has a significant influence on the temporary dormant state of H1299 cells. For the first time, we demonstrated polyploid giant and/or multinucleated cancer-cell (PGCC/MGCC) fractions mainly featuring the progressively augmenting Ki67^low phenotype in CD44+ and CD133+ A549 cells at 24-48 h after IR. In contrast, the Ki67^high phenotype enrichment in the same fractions of all the sorted H1299 cells suggested an increase in their cycling/heterochromatin reorganization activity after IR stress. Our results proposed that entering the "quiescence" state rather than p21-mediated SIPS may play a significant role in the survival of p53wt CSC-like NSCLC cells after IR. The results obtained are important for the selection of therapeutic schemes for the treatment of patients with NSCLC, depending on the functioning of the p53 system in tumor cells.

Downregulation of beclin 1 restores arsenite-induced impaired autophagic flux by improving the lysosomal function in the brain

Arsenite is a toxic metalloid that causes various adverse effects in the brain. However, the underlying mechanisms of arsenite-induced neurotoxicity remain poorly understood. In this study, both adult beclin 1^+/+ and beclin 1^+/- mice were employed to establish a model of chronic arsenite exposure by treating with arsenite via drinking water for 6 months. The results clearly demonstrated that exposure to arsenite profoundly caused damage to the cerebral cortex, induced autophagy and impaired autophagic flux in the cerebral cortex. Heterozygous disruption of beclin 1 in animals remarkably alleviated the neurotoxic effects of arsenite. To verify the results obtained in the animals, a permanent U251 cell line was used. After treating of cells with arsenite, similar phenomenon was also observed, showing the significant elevation in the expression levels of autophagy-related genes. Importantly, lysosomal dysfunction caused by arsenite was observed in vitro and in vivo. Either knockdown of beclin 1 in cells or heterozygous disruption of beclin 1 in animals remarkably alleviated the lysosomal dysfunction induced by arsenite. These findings indicate that downregulation of beclin 1 could restore arsenite-induced impaired autophagic flux possibly through improving lysosomal function, and correct that regulation of autophagy via beclin 1 would be an alternative approach for the treatment of arsenite neurotoxicity.

MITF Promotes Cell Growth, Migration and Invasion in Clear Cell Renal Cell Carcinoma by Activating the RhoA/YAP Signal Pathway

Simple Summary

Microphthalmia-associated transcription factor (MITF) has been reported to play a role in the progression of melanoma and other cancer types. However, the biological role of MITF in clear cell renal cell carcinoma (ccRCC) is largely unknown. In this study, we elucidate the role of MITF in the progression of ccRCC. MITF- and MITF-mediated signaling pathways were investigated in ccRCC cell through MITF knockdown as well as overexpression of MITF in vitro and in vivo. MITF contributed to cell proliferation, migration, invasion and tumor growth in ccRCC through activation of the RhoA/YAP signaling pathways. This study suggests that MITF has potential as a therapeutic target in ccRCC.

Abstract

Microphthalmia-associated transcription factor (MITF) is a basic helix-loop-helix leucine zipper transcription factor involved in the lineage-specific regulation of melanocytes, osteoclasts and mast cells. MITF is also involved in the progression of melanomas and other carcinomas, including the liver, pancreas and lung. However, the role of MITF in clear cell renal cell carcinoma (ccRCC) is largely unknown. This study investigates the functional role of MITF in cancer and the molecular mechanism underlying disease progression in ccRCC. MITF knockdown inhibited cell proliferation and shifted the cell cycle in ccRCC cells. In addition, MITF knockdown reduced wound healing, cell migration and invasion compared with the controls. Conversely, MITF overexpression in SN12C and SNU482 cells increased cell migration and invasion. Overexpression of MITF activated the RhoA/YAP signaling pathway, which regulates cell proliferation and invasion, and increased YAP signaling promoted cell cycle-related protein expression. Additionally, tumor formation was impaired by MITF knockdown and enhanced by MITF overexpression in vivo. In summary, MITF expression was associated with aggressive tumor behavior, and increased the migratory and invasive capabilities of ccRCC cells. These effects were reversed by MITF suppression. These results suggest that MITF is a potential therapeutic target for the treatment of ccRCC.

Therapeutic potential of AMPK signaling targeting in lung cancer: Advances, challenges and future prospects

Lung cancer (LC) is a leading cause of death worldwide with high mortality and morbidity. A wide variety of risk factors are considered for LC development such as smoking, air pollution and family history. It appears that genetic and epigenetic factors are also potential players in LC development and progression. AMP-activated protein kinase (AMPK) is a signaling pathway with vital function in inducing energy balance and homeostasis. An increase in AMP:ATP and ADP:ATP ratio leads to activation of AMPK signaling by upstream mediators such as LKB1 and CamKK. Dysregulation of AMPK signaling is a common finding in different cancers, particularly LC. AMPK activation can significantly enhance LC metastasis via EMT induction. Upstream mediators such as PLAG1, IMPAD1, and TUFM can regulate AMPK-mediated metastasis. AMPK activation can promote proliferation and survival of LC cells via glycolysis induction. In suppressing LC progression, anti-tumor compounds including metformin, ginsenosides, casticin and duloxetine dually induce/inhibit AMPK signaling. This is due to double-edged sword role of AMPK signaling in LC cells. Furthermore, AMPK signaling can regulate response of LC cells to chemotherapy and radiotherapy that are discussed in the current review.

Modulation of Autophagy in Cancer Cells by Dietary Polyphenols

The role of autophagy is to degrade damaged or unnecessary cellular structures. Both in vivo and in vitro studies suggest a dual role of autophagy in cancer—it may promote the development of neoplasms, but it may also play a tumor protective function. The mechanism of autophagy depends on the genetic context, tumor stage and type, tumor microenvironment, or clinical therapy used. Autophagy also plays an important role in cell death as well as in the induction of chemoresistance of cancer cells. The following review describes the extensive autophagic cell death in relation to dietary polyphenols and cancer disease. The review documents increasing use of polyphenolic compounds in cancer prevention, or as agents supporting oncological treatment. Polyphenols are organic chemicals that exhibit antioxidant, anti-inflammatory, anti-angiogenic, and immunomodulating properties, and can also initiate the process of apoptosis. In addition, polyphenols reduce oxidative stress and protect against reactive oxygen species. This review presents in vitro and in vivo studies in animal models with the use of polyphenolic compounds such as epigallocatechin-3-gallate (EGCG), oleuropein, punicalgin, apigenin, resveratrol, pterostilbene, or curcumin and their importance in the modulation of autophagy-induced death of cancer cells.