Cancer cell lines involving cancer stem cell populations respond to oxidative stress

The Antiproliferative Activity of Adiantum pedatum Extract and/or Piceatannol in Phenylhydrazine-Induced Colon Cancer in Male Albino Rats: The miR-145 Expression of the PI-3K/Akt/p53 and Oct4/Sox2/Nanog Pathways

Colon cancer is one of the most common types of cancer worldwide, and its incidence is increasing. Despite advances in medical science, the treatment of colon cancer still poses a significant challenge. This study aimed to investigate the potential protective effects of Adiantum pedatum (AP) extract and/or piceatannol on colon cancer induced via phenylhydrazine (PHZ) in terms of the antioxidant and apoptotic pathways and histopathologic changes in the colons of male albino rats. The rats were randomly divided into eight groups: control, AP extract, piceatannol (P), PHZ, PHZ and AP treatments, PHZ and P treatments, PHZ and both AP and P, and PHZ and prophylaxis with both AP and P. The results demonstrated that PHZ induced oxidative damage, apoptosis, and histopathological changes compared to the control group. However, the administration of AP or P or AP + P as therapy or prophylaxis significantly ameliorated these changes and upregulated the colonic mir-145 and mRNA expression of P53 and PDCD-4 while downregulating the colonic mRNA expression of PI3K, AKT, c-Myc, CK-20, SOX-2, OCT-4, and NanoG compared to the PHZ group. These findings suggest that the candidate drugs may exert their anti-cancer effects through multiple mechanisms, including antioxidant and apoptotic activities.

Chloroquine Enhances Death in Lung Adenocarcinoma A549 Cells Exposed to Cold Atmospheric Plasma Jet

Cold atmospheric plasma (CAP) is an intensively-studied approach for the treatment of malignant neoplasms. Various active oxygen and nitrogen compounds are believed to be the main cytotoxic effectors on biotargets; however, the comprehensive mechanism of CAP interaction with living cells and tissues remains elusive. In this study, we experimentally determined the optimal discharge regime (or semi-selective regime) for the direct CAP jet treatment of cancer cells, under which lung adenocarcinoma A549, A427 and NCI-H23 cells demonstrated substantial suppression of viability, coupled with a weak viability decrease of healthy lung fibroblasts Wi-38 and MRC-5. The death of CAP-exposed cancer and healthy cells under semi-selective conditions was caspase-dependent. We showed that there was an accumulation of lysosomes in the treated cells. The increased activity of lysosomal protease Cathepsin D, the transcriptional upregulation of autophagy-related MAPLC3B gene in cancer cells and the changes in autophagy-related proteins may have indicated the activation of autophagy. The addition of the autophagy inhibitor chloroquine (CQ) after the CAP jet treatment increased the death of A549 cancer cells in a synergistic manner and showed a low effect on the viability of CAP-treated Wi-38 cells. Downregulation of Drp1 mitochondrial protein and upregulation of PINK1 protein in CAP + CQ treated cells indicated that CQ increased the CAP-dependent destabilization of mitochondria. We concluded that CAP weakly activated pro-survival autophagy in irradiated cells, and CQ promoted CAP-dependent cell death due to the destabilization of autophagosomes formation and mitochondria homeostasis. To summarize, the combination of CAP treatment with CQ could be useful for the development of cold plasma-based antitumor approaches for clinical application.

Reversal of cisplatin resistance by neferine/isoliensinine and their combinatorial regimens with cisplatin-induced apoptosis in cisplatin-resistant colon cancer stem cells (CSCs)

Cisplatin chemotherapy to the colorectal cancer cells (CRCs) is accompanied by dose-limiting adverse effects along with the acquisition of drug resistance implicating low therapeutic outcomes. The present study is aimed to evaluate the chemosensitizing efficacy of neferine/isoliensinine or combinatorial regimen of neferine/isoliensinine with cisplatin against CSCs (cisplatin resistant colon stem cells). CSCs were developed using pulse exposure of cisplatin to parental HCT-15 cells. Neferine/isoliensinine or combinatorial regimens of Neferine/isoliensinine and cisplatin exhibited a stronger cytotoxic activity against CSCs compared to control. IC₅₀ doses were found to be 6.5 μM for neferine, 12.5 μM for isoliensinine, and 120 μM for cisplatin respectively. Furthermore, the combinatorial regimen of a low dose of cisplatin (40 μM) with 4 μM neferine/8 μM isoliensinine induced cell death in a synergistic manner as described by isobologram. Neferine/isoliensinine could confer extensive intracellular reactive oxygen species generation in CSCs. Neferine/isoliensinine or combinatorial regimens dissipated mitochondrial membrane potential and enhanced intracellular [Ca²⁺ ]i, which were measured by spectroflurimetry. Furthermore, these combinatorial regimens induced a significant increase in the sub G0 phase of cell cycle arrest and PI uptake and alleviated the expression of ERCC1 in CSCs. Combinatorial regimens or neferine/isoliensinine treatments downregulated the cell survival protein expression (PI3K/pAkt/mTOR) and activated mitochondria-mediated apoptosis by upregulating Bax, cytochrome c, caspase-3, and PARP cleavage expression while downregulating the BCl-2 expression in CSCs. Our study confirms the chemosensitizing efficacy of neferine/isoliensinine or combinatorial regimens of neferine/isoliensinine with a low dose of cisplatin against CSCs.

Comparative microsomal proteomics of a model lung cancer cell line NCI-H23 reveals distinct differences between molecular profiles of 3D and 2D cultured cells

Lung cancer is the leading cause of cancer-related deaths in the USA and worldwide. Yet, about 95% of new drug candidates validated in preclinical phase eventually fail in clinical trials. Such a high attrition rate is attributed mostly to the inability of conventional two-dimensionally (2D) cultured cancer cells to mimic native three-dimensional (3D) growth of malignant cells in human tumors. To ascertain phenotypical differences between these two distinct culture conditions, we carried out a comparative proteomic analysis of a membrane fraction obtained from 3D- and 2D-cultured NSCLC model cell line NCI-H23. This analysis revealed a map of 1,166 (24%) protein species regulated in culture dependent manner, including differential regulation of a subset of cell surface-based CD molecules. We confirmed exclusive expression of CD99, CD146 and CD239 in 3D culture. Furthermore, label-free quantitation, targeting KRas proteoform-specific peptides, revealed upregulation of both wild type and monoallelic KRas4BG12C mutant at the surface of 3D cultured cells. In order to reduce the high attrition rate of new drug candidates, the results of this study strongly suggests exploiting base-line molecular profiling of a large number of patient-derived NSCLC cell lines grown in 2D and 3D culture, prior to actual drug candidate testing.

Pterostilbene Increases LDL Metabolism in HL-1 Cardiomyocytes by Modulating the PCSK9/HNF1α/SREBP2/LDLR Signaling Cascade, Upregulating Epigenetic hsa-miR-335 and hsa-miR-6825, and LDL Receptor Expression

Proprotein convertase subtilisin/kexin type 9 (PCSK9) can promote the degradation of low-density lipoprotein (LDL) receptor (LDLR), leading to hypercholesterolemia and myocardial dysfunction. The intracellular regulatory mechanism by which the natural polyphenol pterostilbene modulates the PCSK9/LDLR signaling pathway in cardiomyocytes has not been evaluated. We conducted Western blotting, flow cytometry, immunofluorescence staining, and mean fluorescence intensity analyses of pterostilbene-treated mouse HL-1 cardiomyocytes. Pterostilbene did not alter cardiomyocyte viability. Compared to the control group, treatment with both 2.5 and 5 μM pterostilbene significantly increased the LDLR protein expression accompanied by increased uptake of LDL. The expression of the mature PCSK9 was significantly suppressed at the protein and mRNA level by the treatment with both 2.5 and 5 μM pterostilbene, respectively, compared to the control. Furthermore, 2.5 and 5 μM pterostilbene treatment resulted in a significant reduction in the protein hepatic nuclear factor 1α (HNF1α)/histone deacetylase 2 (HDAC2) ratio and sterol regulatory element-binding protein-2 (SREBP2)/HDAC2 ratio. The expression of both hypoxia-inducible factor-1 α (HIF1α) and nuclear factor erythroid 2-related factor 2 (Nrf2) at the protein level was also suppressed. Pterostilbene as compared to short hairpin RNA against SREBP2 induced a higher protein expression of LDLR and lower nuclear accumulation of HNF1α and SREBP2. In addition, pterostilbene reduced PCSK9/SREBP2 interaction and mRNA expression by increasing the expression of hsa-miR-335 and hsa-miR-6825, which, in turn, increased LDLR mRNA expression. In cardiomyocytes, pterostilbene dose-dependently decreases and increases the protein and mRNA expression of PCSK9 and LDLR, respectively, by suppressing four transcription factors, HNF1α, SREBP2, HIF1α, and Nrf2, and enhancing the expression of hsa-miR-335 and hsa-miR-6825, which suppress PCSK9/SREBP2 interaction.

A Cyclometalated IrIII Complex Conjugated to a Coumarin Derivative Is a Potent Photodynamic Agent against Prostate Differentiated and Tumorigenic Cancer Stem Cells

A cyclometalated Ir^III complex conjugated to a far-red-emitting coumarin, Ir^III -COUPY (3), was recently shown as a very promising photosensitizer suitable for photodynamic therapy of cancer. Therefore, the primary goal of this work was to deepen knowledge on the mechanism of its photoactivated antitumor action so that this information could be used to propose a new class of compounds as drug candidates for curing very hardly treatable human tumors, such as androgen resistant prostatic tumors of metastatic origin. Conventional anticancer chemotherapies exhibit several disadvantages, such as limited efficiency to target cancer stem cells (CSCs), which are considered the main reason for chemotherapy resistance, relapse, and metastasis. Herein, we show, using DU145 tumor cells, taken as the model of hormone-refractory and aggressive prostate cancer cells resistant to conventional antineoplastic drugs, that the photoactivated conjugate 3 very efficiently eliminates both prostate bulk (differentiated) and prostate hardly treatable CSCs simultaneously and with a similar efficiency. Notably, the very low toxicity of Ir^III -COUPY conjugate in the prostate DU145 cells in the dark and its pronounced selectivity for tumor cells compared with noncancerous cells could result in low side effects and reduced damage of healthy cells during the photoactivated therapy by this agent. Moreover, the experiments performed with the 3D spheroids formed from DU145 CSCs showed that conjugate 3 can penetrate the inner layers of tumor spheres, which might markedly increase its therapeutic effect. Also interestingly, this conjugate induces apoptotic cell death in prostate cancer DU145 cells associated with calcium signaling flux in these cells and autophagy. To the best of our knowledge, this is the first study demonstrating that a photoactivatable metal-based compound is an efficient agent capable of killing even hardly treatable CSCs.

Toxicological Evaluation of Piceatannol, Pterostilbene, and ε-Viniferin for Their Potential Use in the Food Industry: A Review

The application of stilbenes in the food industry is being considered because of their biological activities. Piceatannol, pterostilbene and ε-viniferin have awakened the industry’s interest. However, before they can be commercialized, we must first guarantee their safety for consumers. The present work reviews the toxicological studies performed with these stilbenes. A wide variety of studies has demonstrated their cytotoxic effects in both cancer and non-cancerous cell lines. In contrast, although DNA damage was detected by some authors, in vitro genotoxic studies on the effects of piceatannol, pterostilbene, and ε-viniferin remain scarce. None of the three reviewed substances have been evaluated using the in vitro tests required by the European Food Safety Authority (EFSA) as the first step in genotoxicity testing. We did not find any study on the toxic effects of these stilbenes in vivo. Thus, more studies are needed to confirm their safe use before they can be authorized as additive in the food industry.

Advancements in Cancer Stem Cell Isolation and Characterization

Occurrence of stem cells (CSCs) in cancer is well established in last two decades. These rare cells share several properties including presence of common surface markers, stem cell markers, chemo- and radio- resistance and are highly metastatic in nature; thus, considered as valuable prognostic and therapeutic targets in cancer. However, the studies related to CSCs pave number of issues due to rare cell population and difficulties in their isolation ascribed to common stem cell marker. Various techniques including flow cytometry, laser micro-dissection, fluorescent nanodiamonds and microfluidics are used for the isolation of these rare cells. In this review, we have included the advance strategies adopted for the isolation of CSCs using above mentioned techniques. Furthermore, CSCs are primarily found in the core of the solid tumors and their microenvironment plays an important role in maintenance, self-renewal, division and tumor development. Therefore, in vivo tracking and model development become obligatory for functional studies of CSCs. Fluorescence and bioluminescence tagging has been widely used for transplantation assay and lineage tracking experiments to improve our understanding towards CSCs behaviour in their niche. Techniques such as Magnetic resonance imaging (MRI) and Positron emission tomography (PET) have proved useful for tracking of endogenous CSCs which could be helpful in their identification in clinical settings.

Thiosemicarbazone-metal complexes exhibiting cytotoxicity in colon cancer cell lines through oxidative stress

Colorectal cancer is the third most common type of cancer and has a high incidence in developed countries. At present, specific treatments are being required to allow individualized therapy depending on the molecular alteration on which the drug may act. The aim of this project is to evaluate whether HPTSC and HPTSC* thiosemicarbazones (HPTSC = pyridine-2-carbaldehyde thiosemicarbazone and HPTSC* = pyridine-2-carbaldehyde 4N-methylthiosemicarbazone), and their complexes with different transition metal ions as Cu(II), Fe(III) and Co(III), have antitumor activity in colon cancer cells (HT-29 and SW-480), that have different oncogenic characteristics. Cytotoxicity was evaluated and the involvement of oxidative stress in its mechanism of action was analyzed by quantifying the superoxide dismutase activity, redox state by quantification of the thioredoxin levels and reduced/oxidized glutathione rate and biomolecules damage. The apoptotic effect was evaluated by measurements of the levels of caspase 9 and 3 and the index of histones. All the metal-thiosemicarbazones have antitumor activity mediated by oxidative stress. The HPTSC*-Cu was the compound that showed the best antitumor and apoptotic characteristics for the cell line SW480, that is KRAS gene mutated.

Anti-Proliferative and Pro-Apoptotic Effects of Calligonum comosum (L'Her.) Methanolic Extract in Human Triple-Negative MDA-MB-231 Breast Cancer Cells

Triple-negative breast cancer (TNBC), the most aggressive subtype, does not respond to targeted therapy due to the lack of hormone receptors. There is an urgent need for alternative therapies, including natural product-based anti-cancer drugs, at lower cost. We investigated the impact of a Calligonum comosum L'Hér. methanolic extract (CcME) on the TNBC MDA-MB-231 cell line proliferation and related cell death mechanisms performing cell viability and cytotoxicity assays, flow cytometry to detect apoptosis and cell cycle analysis. The apoptosis-related protein array and cellular reactive oxygen species (ROS) assay were also carried out. We showed that the CcME inhibited the TNBC cell viability, in a dose-dependent manner, with low cytotoxic effects. The CcME-treated TNBC cells underwent apoptosis, associated with a concomitant increase of apoptosis-related protein expression, including cytochrome c, cleaved caspase-3, cyclin-dependent kinase inhibitor p21, and the anti-oxidant enzyme catalase, compared with the untreated cells. The CcME also enhanced the mitochondrial transition pore opening activity and induced G0/G1 cell growth arrest, which confirmed the cytochrome c release and the increase of the p21 expression detected in the CcME-treated TNBC cells. The CcME-treated TNBC cells resulted in intracellular ROS production, which, when blocked with a ROS scavenger, did not reduce the CcME-induced apoptosis. In conclusion, CcME exerts anti-proliferative effects against TNBC cells through the induction of apoptosis and cell growth arrest. In vivo studies are justified to verify the CcME anti-proliferative activities and to investigate any potential anti-metastatic activities of CcME against TNBC development and progression.

In Vitro Toxicity Assessment of Stilbene Extract for Its Potential Use as Antioxidant in the Wine Industry

The reduction of sulfur dioxide in wine is a consumer's demand, considering the allergic effects that may occur in people who are sensitive to it. Stilbenes are candidates of great interest for this purpose because of their antioxidant/antimicrobial activities and health properties, and also because they are naturally found in the grapevine. In the present study, the in vitro toxicity of an extract from grapevine shoots (with a stilbene richness of 45.4%) was assessed in two human cell lines. Significant damage was observed from 30 μg/mL after 24 h, and 40 µg/mL after 48 h of exposure. Similarly, the ultrastructural study revealed a significant impairment of cell growing. The extract was able to protect cells against an induced oxidative stress at all concentrations studied. In view of the promising results, a more exhaustive toxicological assessment of the extract is needed to confirm the safety of its further use as additive in wine.

Co-regulatory Network of Oncosuppressor miRNAs and Transcription Factors for Pathology of Human Hepatic Cancer Stem Cells (HCSC)

Hepatic cancer stem cells (HCSCs) are considered as main players for the hepatocellular carcinoma (HCC) initiation, metastasis, drug resistance and recurrence. There is a growing evidence supporting the down-regulated miRNAs in HCSCs as key suppressors for the stemness traits, but still more details are vague about how these miRNAs modulate the HCC development. To uncover some of these miRNA regulatory aspects in HCSC, we compiled 15 down-regulated miRNA and their validated and predicted up-regulated targets in HCSC. The targets were enriched for several cancer cell stemness hallmarks and CSC pre-metastatic niche, which support these miRNAs role in suppression of HCSCs neoplastic transformation. Further, we constructed miRNA-Transcription factor (TF) regulatory networks, which provided new insights on the role of the proposed miRNA-TF co-regulation in the cancer stemness axis and its cross talk with the surrounding microenvironment. Our analysis revealed HCSC important hubs as candidate regulators for targeting hepatic cancer stemness such as, miR-148a, miR-214, E2F family, MYC and SLC7A5. Finally, we proposed a possible model for miRNA and TF co-regulation of HCSC signaling pathways. Our study identified an HCSC signature and set bridges between the reported results to give guide for future validation of HCC therapeutic strategies avoiding drug resistance.