From rest to repair: Safeguarding genomic integrity in quiescent cells.

Quiescence is an important non-pathological state in which cells pause cell cycle progression temporarily, sometimes for decades, until they receive appropriate proliferative stimuli. Quiescent cells make up a significant proportion of the body, and maintaining genomic integrity during quiescence is crucial for tissue structure and function. While cells in quiescence are spared from DNA damage associated with DNA replication or mitosis, they are still exposed to various sources of endogenous DNA damage, including those induced by normal transcription and metabolism. As such, it is vital that cells retain their capacity to effectively repair lesions that may occur and return to the cell cycle without losing their cellular properties. Notably, while DNA repair pathways are often found to be downregulated in quiescent cells, emerging evidence suggests the presence of active or differentially regulated repair mechanisms. This review aims to provide a current understanding of DNA repair processes during quiescence in mammalian systems and sheds light on the potential pathological consequences of inefficient or inaccurate repair in quiescent cells.

Autophagic degradation of CDK4 is responsible for G0/G1 cell cycle arrest in NVP-BEZ235-treated neuroblastoma.

BACKGROUND: CDK4 is highly expressed and associated with poor prognosis and decreased survival in advanced neuroblastoma (NB). Targeting CDK4 degradation presents a potentially promising therapeutic strategy compared to conventional CDK4 inhibitors. However, the autophagic degradation of the CDK4 protein and its anti-proliferation effect in NB cells has not been mentioned. RESULTS: We identified autophagy as a new pathway for the degradation of CDK4. Firstly, autophagic degradation of CDK4 is critical for NVP-BEZ235-induced G0/G1 arrest, as demonstrated by the overexpression of CDK4, autophagy inhibition, and blockade of autophagy-related genes. Secondly, we present the first evidence that p62 binds to CDK4 and then enters the autophagy-lysosome to degrade CDK4 in a CTSB-dependent manner in NVP-BEZ235 treated NB cells. Similar results regarding the interaction between p62 and CDK4 were observed in the NVP-BEZ235 treated NB xenograft mouse model. CONCLUSIONS: Autophagic degradation of CDK4 plays a pivotal role in G0/G1 cell cycle arrest in NB cells treated with NVP-BEZ235.

An image-based screen for secreted proteins involved in breast cancer G0 cell cycle arrest.

Secreted proteins regulate the balance between cellular proliferation and G0 arrest and therefore play important roles in tumour dormancy. Tumour dormancy presents a significant clinical challenge for breast cancer patients, where non-proliferating, G0-arrested cancer cells remain at metastatic sites, below the level of clinical detection, some of which can re-enter proliferation and drive tumour relapse. Knowing which secreted proteins can regulate entry into and exit from G0 allows us to manipulate their signalling to prevent tumour relapse. To identify novel secreted proteins that can promote breast cancer G0 arrest, we performed a secretome-wide, image-based screen for proteins that increase the fraction of cells in G0 arrest. From a secretome library of 1282 purified proteins, we identified 29 candidates that promote G0 arrest in non-transformed and transformed breast epithelial cells. The assay we have developed can be adapted for use in other perturbation screens in other cell types. All datasets have been made available for re-analysis and our candidate proteins are presented for alternative bioinformatic refinement or further experimental follow up.

Blockade of CaV3 calcium channels and induction of G0/G1 cell cycle arrest in colon cancer cells by gossypol.

BACKGROUND AND PURPOSE: Gastrointestinal tumours overexpress voltage-gated calcium (CaV3) channels (CaV3.1, 3.2 and 3.3). CaV3 channels regulate cell growth and apoptosis colorectal cancer. Gossypol, a polyphenolic aldehyde found in the cotton plant, has anti-tumour properties and inhibits CaV3 currents. A systematic study was performed on gossypol blocking mechanism on CaV3 channels and its potential anticancer effects in colon cancer cells, which express CaV3 isoforms. EXPERIMENTAL APPROACH: Transcripts for CaV3 proteins were analysed in gastrointestinal cancers using public repositories and in human colorectal cancer cell lines HCT116, SW480 and SW620. The gossypol blocking mechanism on CaV3 channels was investigated by combining heterologous expression systems and patch-clamp experiments. The anti-tumoural properties of gossypol were estimated by cell proliferation, viability and cell cycle assays. Ca2+ dynamics were evaluated with cytosolic and endoplasmic reticulum (ER) Ca2+ indicators. KEY RESULTS: High levels of CaV3 transcripts correlate with poor prognosis in gastrointestinal cancers. Gossypol blockade of CaV3 isoforms is concentration- and use-dependent interacting with the closed, activated and inactivated conformations of CaV3 channels. Gossypol and CaV3 channels down-regulation inhibit colorectal cancer cell proliferation by arresting cell cycles at the G0/G1 and G2/M phases, respectively. CaV3 channels underlie the vectorial Ca2+ uptake by endoplasmic reticulum in colorectal cancer cells. CONCLUSION AND IMPLICATIONS: Gossypol differentially blocked CaV3 channel and its anticancer activity was correlated with high levels of CaV3.1 and CaV3.2 in colorectal cancer cells. The CaV3 regulates cell proliferation and Ca2+ dynamics in colorectal cancer cells. Understanding this blocking mechanism maybe improve cancer therapies.

Clotrimazole inhibits growth of multiple myeloma cells in vitro via G0/G1 arrest and mitochondrial apoptosis.

Patients with multiple myeloma (MM) experience relapse and drug resistance; therefore, novel treatments are essential. Clotrimazole (CTZ) is a wide-spectrum antifungal drug with antitumor activity. However, CTZ's effects on MM are unclear. We investigated CTZ's effect on MM cell proliferation and apoptosis induction mechanisms. CTZ's effects on MM.1S, NCI- H929, KMS-11, and U266 cell growth were investigated using Cell Counting Kit-8 (CCK-8) assay. The apoptotic cell percentage was quantified with annexin V-fluorescein isothiocyanate/7-amino actinomycin D staining. Mitochondrial membrane potential (MMP) and cell cycle progression were evaluated. Reactive oxygen species (ROS) levels were measured via fluorescence microscopy. Expression of apoptosis-related and nuclear factor (NF)-κB signaling proteins was analyzed using western blotting. The CCK-8 assay indicated that CTZ inhibited cell proliferation based on both dose and exposure time. Flow cytometry revealed that CTZ decreased apoptosis and MMP and induced G0/G1 arrest. Immunofluorescence demonstrated that CTZ dose-dependently elevated in both total and mitochondrial ROS production. Western blotting showed that CTZ enhanced Bax and cleaved poly ADP-ribose polymerase and caspase-3 while decreasing Bcl-2, p-p65, and p-IκBα. Therefore, CTZ inhibits MM cell proliferation by promoting ROS-mediated mitochondrial apoptosis, inducing G0/G1 arrest, inhibiting the NF-κB pathway, and has the potential for treating MM.

Citalopram, an antipsychotic agent, induces G1/G0 phase cell cycle arrest and promotes apoptosis in human laryngeal carcinoma HEP-2 cells.

Human laryngeal squamous carcinoma (LSCC) is a common malignant tumor in the head and neck. Despite the recently developed therapies for the treatment of LSCC, patients' overall survival rate still did not enhance remarkably; this highlights the need to formulate alternative strategies to develop novel treatments. The antitumor effects of antidepressant drugs such as citalopram have been reported on several cancer cells; however, they have yet to be investigated against LSCC. The current study was directed to explore the possible antitumor effects of citalopram on human laryngeal carcinoma cell lines (HEP-2). HEP-2 cells were cultured and treated with different doses of citalopram (50-400 µM) for 24, 48, and 72 h. The effects of citalopram on the viability of cancer cells were determined by the MTT assay. In addition, apoptosis and cell cycle analysis were performed by flow cytometry. Moreover, evaluation of the expression of proapoptotic and apoptotic proteins, such as cytochrome c, cleaved caspases 3 and 9, Bcl-2, and BAX, was performed by western blotting analysis. Our results revealed that citalopram significantly suppressed the proliferation of HEP-2 cells through the upregulation of p21 expression, resulting in the subsequent arrest of the cell cycle at the G0/G1 phase. Furthermore, citalopram treatment-induced HEP-2 cell apoptosis; this was indicated by the significant increase of cytochrome c, cleaved caspases 3 and 9, and BAX protein expression. On the contrary, Bcl-2 protein expression was significantly downregulated following treatment with citalopram. The ultrastructure studies were in accordance with the protein expression findings and showed clear signs of apoptosis with ring chromatin condensation upon treatment with citalopram. These findings suggest that citalopram's anti-tumor activities on HEP-2 cells entailed stimulation of the intrinsic apoptotic pathway, which was mediated via Bcl-2 suppression.

Evaluation of the anticancer effect of telomerase inhibitor BIBR1532 in anaplastic thyroid cancer in terms of apoptosis, migration and cell cycle.

Anaplastic thyroid cancer (ATC) represents the type with the worst prognosis among thyroid cancers. In ATC with a highly invasive phenotype, selective targeting of TERT with BIBR1532 may be a goal-driven approach to preserving healthy tissues. In present study, it was aimed to investigate the effects of treatment of SW1736 cells with BIBR1532 on apoptosis, cell cycle progression, and migration. The apoptotic effect of BIBR1532 on SW1736 cells was examined using the Annexin V method, the cytostatic effect using cell cycle test, migration properties using wound healing assay. Gene expression differences were determined by real-time qRT-PCR and differences in protein level by ELISA test. BIBR1532-treated SW1736 cells had 3.1-fold increase in apoptosis compared to their untreated counterpart. There was 58.1% arrest in the G0/G1 phase and 27.6% arrest in the S phase of the cell cycle in untreated group, treatment with BIBR1532 increased cell population in G0/G1 phase to 80.9% and decreased in S phase to 7.1%. Treatment with the TERT inhibitor resulted in a 50.8% decrease in cell migration compared to the untreated group. After BIBR1532 treatment of SW1736 cells, upregulation of BAD, BAX, CASP8, CYCS, TNFSF10, CDKN2A genes, and downregulation of BCL2L11, XIAP, CCND2 genes were detected. BIBR1532 treatment resulted in an increase in BAX and p16 proteins, and a decrease in concentration of BCL-2 protein compared to untreated group. Targeting TERT with BIBR1532 as a mono drug or using of BIBR1532 at "priming stage" prior to chemotherapy treatment in ATC may present a novel and promising treatment strategy.

Heparin and calreticulin interact on the surface of early G0/G1 dividing rat mesangial cells to regulate hyperglycemic glucose-induced responses.

Heparin can block pathological responses associated with diabetic nephropathy in animal models and human patients. Our previous studies showed that the interaction of heparin on the surface of rat mesangial cells (RMCs) entering G1 of cell division in hyperglycemic glucose: 1) blocked glucose uptake by glucose transporter 4; 2) inhibited cytosolic uridine diphosphate-glucose elevation that would occur within 6 h from G0/G1; and 3) prevented subsequent activation of hyaluronan synthesis in intracellular compartments and subsequent inflammatory responses. However, specific proteins that interact with heparin are unresolved. Here, we showed by live cell imaging that fluorescent heparin was rapidly internalized into the cytoplasm and then into the endoplasmic reticulum, Golgi, and nuclei compartments. Biotinylated-heparin was applied onto the surface of growth arrested G0/G1 RMCs in order to extract heparin-binding protein(s). SDS-PAGE gels showed two bands at ∼70 kDa in the extract that were absent when unlabeled heparin was used to compete. Trypsin digests of the bands were analyzed by MS and identified as calreticulin and prelamin A/C. Immunostaining with their antibodies identified the presence of calreticulin on the G0/G1 RMC cell surface. Previous studies have shown that calreticulin can be on the cell surface and can interact with the LDL receptor-related protein, which has been implicated in glucose transport by interaction with glucose transporter 4. Thus, cell surface calreticulin can act as a heparin receptor through a mechanism involving LRP1, which prevents the intracellular responses in high glucose and reprograms the cells to synthesize an extracellular hyaluronan matrix after division.

Quiescent Cancer Cells-A Potential Therapeutic Target to Overcome Tumor Resistance and Relapse.

Quiescent cancer cells (QCCs) are nonproliferating cells arrested in the G0 phase, characterized by ki67low and p27high. QCCs avoid most chemotherapies, and some treatments could further lead to a higher proportion of QCCs in tumors. QCCs are also associated with cancer recurrence since they can re-enter a proliferative state when conditions are favorable. As QCCs lead to drug resistance and tumor recurrence, there is a great need to understand the characteristics of QCCs, decipher the mechanisms that regulate the proliferative-quiescent transition in cancer cells, and develop new strategies to eliminate QCCs residing in solid tumors. In this review, we discussed the mechanisms of QCC-induced drug resistance and tumor recurrence. We also discussed therapeutic strategies to overcome resistance and relapse by targeting QCCs, including (i) identifying reactive quiescent cancer cells and removing them via cell-cycle-dependent anticancer reagents; (ii) modulating the quiescence-to-proliferation switch; and (iii) eliminating QCCs by targeting their unique features. It is believed that the simultaneous co-targeting of proliferating and quiescent cancer cells may ultimately lead to the development of more effective therapeutic strategies for the treatment of solid tumors.

Enhanced recombinant protein production in CHO cell continuous cultures under growth-inhibiting conditions is associated with an arrested cell cycle in G1/G0 phase.

Low temperature and sodium butyrate (NaBu) are two of the most used productivity-enhancing strategies in CHO cell cultures during biopharmaceutical manufacturing. While these two approaches alter the balance in the reciprocal relationship between cell growth and productivity, we do not fully understand their mechanisms of action beyond a gross cell growth inhibition. Here, we used continuous culture to evaluate the differential effect of low temperature and NaBu supplementation on CHO cell performance and gene expression profile. We found that an increase in cell-productivity under growth-inhibiting conditions was associated with the arrest of cells in the G1/G0 phase. A transcriptome analysis revealed that the molecular mechanisms by which low temperature and NaBu arrested cell cycle in G1/G0 differed from each other through the deregulation of different cell cycle checkpoints and regulators. The individual transcriptome changes in pattern observed in response to low temperature and NaBu were retained when these two strategies were combined, leading to an additive effect in arresting the cell cycle in G1/G0 phase. The findings presented here offer novel molecular insights about the cell cycle regulation during the CHO cell bioprocessing and its implications for increased recombinant protein production. This data provides a background for engineering productivity-enhanced CHO cell lines for continuous manufacturing.

Pre-clinical and clinical studies on the role of RBM3 in muscle-invasive bladder cancer: longitudinal expression, transcriptome-level effects and modulation of chemosensitivity.

BACKGROUND: The response to neoadjuvant cisplatin-based chemotherapy (NAC) in muscle-invasive bladder cancer (MIBC) is impaired in up to 50% of patients due to chemoresistance, with no predictive biomarkers in clinical use. The proto-oncogene RNA-binding motif protein 3 (RBM3) has emerged as a putative modulator of chemotherapy response in several solid tumours but has a hitherto unrecognized role in MIBC. METHODS: RBM3 protein expression level in tumour cells was assessed via immunohistochemistry in paired transurethral resection of the bladder (TURB) specimens, cystectomy specimens and lymph node metastases from a consecutive cohort of 145 patients, 65 of whom were treated with NAC. Kaplan-Meier and Cox regression analyses were applied to estimate the impact of RBM3 expression on time to recurrence (TTR), cancer-specific survival (CSS), and overall survival (OS) in strata according to NAC treatment. The effect of siRNA-mediated silencing of RBM3 on chemosensitivity was examined in RT4 and T24 human bladder carcinoma cells in vitro. Cellular functions of RBM3 were assessed using RNA-sequencing and gene ontology analysis, followed by investigation of cell cycle distribution using flow cytometry. RESULTS: RBM3 protein expression was significantly higher in TURB compared to cystectomy specimens but showed consistency between primary tumours and lymph node metastases. Patients with high-tumour specific RBM3 expression treated with NAC had a significantly reduced risk of recurrence and a prolonged CSS and OS compared to NAC-untreated patients. In high-grade T24 carcinoma cells, which expressed higher RBM3 mRNA levels compared to RT4 cells, RBM3 silencing conferred a decreased sensitivity to cisplatin and gemcitabine. Transcriptomic analysis revealed potential involvement of RBM3 in facilitating cell cycle progression, in particular G1/S-phase transition, and initiation of DNA replication. Furthermore, siRBM3-transfected T24 cells displayed an accumulation of cells residing in the G1-phase as well as altered levels of recognised regulators of G1-phase progression, including Cyclin D1/CDK4 and CDK2. CONCLUSIONS: The presented data highlight the potential value of RBM3 as a predictive biomarker of chemotherapy response in MIBC, which could, if prospectively validated, improve treatment stratification of patients with this aggressive disease.

Antitumor Effect of Regorafenib on MicroRNA Expression in Hepatocellular Carcinoma Cell Lines.

Hepatocellular carcinoma (HCC) is the most common primary malignancy of the liver and is one of the leading causes of cancer-related deaths worldwide. Regorafenib, a multi-kinase inhibitor, is used as a second-line treatment for advanced HCC. Here, we aimed to investigate the mechanism of the antitumor effect of regorafenib on HCC and evaluate altered microRNA (miRNA) expression. Cell proliferation was examined in six HCC cell lines (HuH-7, HepG2, HLF, PLC/PRF/5, Hep3B, and Li-7) using the Cell Counting Kit-8 assay. Xenografted mouse models were used to assess the effects of regorafenib in vivo. Cell cycle analysis, western blotting analysis, and miRNA expression analysis were performed to identify the antitumor inhibitory potential of regorafenib on HCC cells. Regorafenib suppressed proliferation in HuH-7 cell and induced G0/G1 cell cycle arrest and cyclin D1 downregulation in regorafenib-sensitive cells. During miRNA analysis, miRNA molecules associated with the antitumor effect of regorafenib were found. Regorafenib suppresses cell proliferation and tumor growth in HCC by decreasing cyclin D1 via alterations in intracellular and exosomal miRNAs in HCC.

Genome-Wide Expression and Anti-Proliferative Effects of Electric Field Therapy on Pediatric and Adult Brain Tumors.

The lack of treatment options for high-grade brain tumors has led to searches for alternative therapeutic modalities. Electrical field therapy is one such area. The Optune™ system is an FDA-approved novel device that delivers continuous alternating electric fields (tumor treating fields-TTFields) to the patient for the treatment of primary and recurrent Glioblastoma multiforme (GBM). Various mechanisms have been proposed to explain the effects of TTFields and other electrical therapies. Here, we present the first study of genome-wide expression of electrotherapy (delivered via TTFields or Deep Brain Stimulation (DBS)) on brain tumor cell lines. The effects of electric fields were assessed through gene expression arrays and combinational effects with chemotherapies. We observed that both DBS and TTFields significantly affected brain tumor cell line viability, with DBS promoting G0-phase accumulation and TTFields promoting G2-phase accumulation. Both treatments may be used to augment the efficacy of chemotherapy in vitro. Genome-wide expression assessment demonstrated significant overlap between the different electrical treatments, suggesting novel interactions with mitochondrial functioning and promoting endoplasmic reticulum stress. We demonstrate the in vitro efficacy of electric fields against adult and pediatric high-grade brain tumors and elucidate potential mechanisms of action for future study.

Tubastatin A maintains adult skeletal muscle stem cells in a quiescent state ex vivo and improves their engraftment ability in vivo.

Adult skeletal muscle stem cells (MuSCs) are important for muscle regeneration and constitute a potential source of cell therapy. However, upon isolation, MuSCs rapidly exit quiescence and lose transplantation potency. Maintenance of the quiescent state in vitro preserves MuSC transplantation efficiency and provides an opportunity to study the biology of quiescence. Here we show that Tubastatin A (TubA), an Hdac6 inhibitor, prevents primary cilium resorption, maintains quiescence, and enhances MuSC survival ex vivo. Phenotypic characterization and transcriptomic analysis of TubA-treated cells revealed that TubA maintains most of the biological features and molecular signatures of quiescence. Furthermore, TubA-treated MuSCs showed improved engraftment ability upon transplantation. TubA also induced a return to quiescence and improved engraftment of cycling MuSCs, revealing a potentially expanded application for MuSC therapeutics. Altogether, these studies demonstrate the ability of TubA to maintain MuSC quiescence ex vivo and to enhance the therapeutic potential of MuSCs and their progeny.

Distinct mechanism of action for antitumoral neutral cyclometalated Pt(II)-complexes bearing antifungal imidazolyl-based drugs.

Three neutral Pt(II) complexes containing 1-Methylimidazole and the antifungal imidazolyl drugs Clotrimazole and Bifonazole have been prepared. The general formula of the new derivatives is [Pt(κ2-(C^N)Cl(L)], where C^N stands for ppy = 2-phenylpyridinate, and L = 1-Methylimidazole (MeIm) for [Pt-MeIm]; L = Clotrimazole (CTZ) for [Pt-CTZ] and L = Bifonazole (BFZ) for [Pt-BFZ]). The complexes have been completely characterized in solution and the crystal structures of [Pt-BFZ] and [Pt-CTZ] have been resolved. Complexes [Pt-MeIm] and [Pt-BFZ] present higher cytotoxicity than cisplatin in SW480 (colon adenocarcinoma), A549 (lung adenocarcinoma) and A2780 (ovarian cancer) cell lines. [Pt-MeIm] shows the highest accumulation in A549 cells, in agreement with its inability to interact with serum albumin. By contrast, [Pt-CTZ] and [Pt-BFZ] interact with serum proteins, a fact that reduces their bioavailability. The strongest interaction with bovine serum albumin (BSA) is found for [Pt-BFZ], which is the least internalized inside the cells. All the complexes are able to covalently interact with DNA. The most cytotoxic complexes, [Pt-MeIm] and [Pt-BFZ] induce cellular accumulation in G0/G1 and apoptosis by a similar pathway, probably involving a reactive oxygen species (ROS) generation mechanism. [Pt-BFZ] turns out to be the most efficient complex regarding ROS generation and causes mitochondrial membrane depolarization, whereas [Pt-MeIm] induces the opposite effect, hyperpolarization of the mitochondrial membrane. On the contrary, the least cytotoxic complex, [Pt-CTZ] cannot block the cell cycle or generate ROS and the mechanism by which it induces apoptosis could be a different one.

Suppression of CDCA3 inhibits prostate cancer progression via NF­κB/cyclin D1 signaling inactivation and p21 accumulation.

Dysregulation of the cell cycle contributes to tumor progression. Cell division cycle­associated 3 (CDCA3) is a known trigger of mitotic entry and has been demonstrated to be constitutively upregulated in tumors. It is therefore associated with carcinogenic properties reported in various cancers. However, the role of CDCA3 in prostate cancer is unclear. In the present study, western blotting and analysis of gene expression profiling datasets determined that CDCA3 expression was upregulated in prostate cancer and was associated with a poor prognosis. CDCA3 knockdown in DU145 and PC­3 cells led to decreased cell proliferation and increased apoptosis, with increased protein expression levels of cleaved­caspase3. Further experiments demonstrated that downregulated CDCA3 expression levels induced G0/G1 phase arrest, which was attributed to increased p21 protein expression levels and decreased cyclin D1 expression levels via the regulation of NF­κB signaling proteins (NFκB­p105/p50, IKKα/ß, and pho­NFκB­p65). In conclusion, these results indicated that CDCA3 may serve a crucial role in prostate cancer and consequently, CDCA3 knockdown may be used as a potential therapeutic target.

Celecoxib prevents tumor necrosis factor-α (TNF-α)-induced cellular senescence in human chondrocytes.

Osteoarthritis (OA) is a cartilage degenerative disease commonly observed in the elderly population and significantly impacts the normal life of OA patients. It has been reported that the development of pathological cell senescence in chondrocytes is involved in the pathogenesis of OA. Celecoxib is a common non-steroidal anti-inflammatory drug, and it has been recently reported to exert therapeutic effects on OA. However, its underlying mechanism is still unclear. The present study intends to explore its mechanism and provide fundamental evidence for the application of Celecoxib in the treatment of clinical OA. Tumor necrosis factor-α (TNF-α) was utilized to establish an in vitro model of chondrocytes senescence. The elevated reactive oxygen species (ROS) generation, increased cell cycle arrest in G0/G1 phase, reduced telomerase activity, and upregulated senescence-associatedß-galactosidase (SA-ß-Gal) staining were all observed in TNF-α-treated chondrocytes, which were then dramatically reversed by 10 and 20 µM Celecoxib. In addition, the upregulated DNA damage biomarkers, p-ATM, and p-CHK2, observed in TNF-α-treated chondrocytes were significantly downregulated by 10 and 20 µM Celecoxib. Lastly, the expression level of p21 and p53 was greatly elevated in chondrocytes by stimulation with TNF-α which was then pronouncedly repressed by treatment with Celecoxib. Taken together, our data reveal that Celecoxib ameliorated TNF-α-induced cellular senescence in human chondrocytes.

Caffeine Induces G0/G1 Cell Cycle Arrest and Inhibits Migration through Integrin αv, ß3, and FAK/Akt/c-Myc Signaling Pathway.

Lung cancer is recognized as a major cause of mortality worldwide owing to its metastatic activity. Given the lack of solid information regarding the possible effects of caffeine, one of the most consumed natural psychoactive substances, on molecular signaling pathways implicated in the aggressive behavior of lung cancer, our study aimed to evaluate the effect and mechanism of caffeine on metastasis-related mechanisms. The results revealed that caffeine treatment at concentrations of 0-500 µM caused no direct cytotoxic effects on NCI-H23 cells. Treatment of cells with caffeine showed good potential to inhibit cell proliferation at 48 h and induced significant cell cycle arrest at the G0/G1 phase. Concerning metastasis, caffeine was shown to reduce filopodia formation, inhibit migration and invasion capability, and reduce the ability of cancer cells to survive and grow in an anchorage-independent manner. Moreover, caffeine could attenuate the formation of 3D tumor spheroids in cancer stem cell (CSC)-enriched populations. With regard to mechanisms, we found that caffeine significantly altered the integrin pattern of the treated cells and caused the downregulation of metastasis-associated integrins, namely, integrins αv and ß3. Subsequently, the downstream signals, including protein signaling and transcription factors, namely, phosphorylated focal adhesion kinase (p-FAK), phosphorylated protein kinase B (p-Akt), cell division cycle 42 (Cdc42), and c-Myc, were significantly decreased in caffeine-exposed cells. Taken together, our novel data on caffeine-inhibiting mechanism in relation to metastasis in lung cancer could provide insights into the impact of caffeine intake on human diseases and conditions.

Telmisartan Exerts Cytotoxicity in Scirrhous Gastric Cancer Cells by Inducing G0/G1 Cell Cycle Arrest.

BACKGROUND/AIM: This study aimed to assess the effects of telmisartan (TEL), a potential antitumor agent, and its mechanism of action in the regulation of apoptosis, autophagy, and cell cycle in scirrhous gastric cancer (SGC). MATERIALS AND METHODS: The effect of TEL on the viability and chromatin condensation of OCUM-2M and OCUM-12 cells was assessed. Protein expression and the cell cycle were analysed using western blotting and flow cytometry, respectively. RESULTS: TEL inhibited cell proliferation in a dose-dependent manner and increased chromatin condensation and autophagy marker LC3-II levels in OCUM-12 cells. TEL also increased the proportion of cells in the G0/G1 phase transition. CONCLUSION: Apoptosis and autophagy are partially involved in the inhibitory effect of TEL on cell proliferation. Additionally, TEL caused G0/G1 cell cycle arrest. Therefore, TEL could be a promising treatment for SGC.