α-Mangostin from Cratoxylum arborescens demonstrates apoptogenesis in MCF-7 with regulation of NF-κB and Hsp70 protein modulation in vitro, and tumor reduction in vivo

Potential Antitumor Effect of α-Mangostin against Rat Mammary Gland Tumors Induced by LA7 Cells

In this study, the chemotherapeutic effect of α-mangostin (AM) was assessed in rats injected with LA7 cells. Rats received AM orally at 30 and 60 mg/kg twice a week for 4 weeks. Cancer biomarkers such as CEA and CA 15-3 were significantly lower in AM-treated rats. Histopathological evaluations showed that AM protects the rat mammary gland from the carcinogenic effects of LA7 cells. Interestingly, AM decreased lipid peroxidation and increased antioxidant enzymes when compared to the control. Immunohistochemistry results of the untreated rats showed abundant PCNA and fewer p53-positive cells than AM-treated rats. Using the TUNEL test, AM-treated animals had higher apoptotic cell numbers than those untreated. This report revealed that that AM lessened oxidative stress, suppressed proliferation, and minimized LA7-induced mammary carcinogenesis. Therefore, the current study suggests that AM has significant potential for breast cancer treatment.

Radiosynthesis, Stability, Lipophilicity, and Cellular Uptake Evaluations of [131I]Iodine-α-Mangostin for Breast Cancer Diagnosis and Therapy

The high rate of incidence and mortality caused by breast cancer encourage urgent research to immediately develop new diagnostic and therapeutic agents for breast cancer. Alpha mangostin (AM) is a natural compound reported to have anti-breast cancer properties. Its electron-donating groups structure allows it to be labeled with an iodine-131 radioisotope to develop a candidate of a diagnostic and therapeutic agent for breast cancer. This study aims to prepare the [^131I]Iodine-α-mangostin ([¹³¹I]I-AM) and evaluate its stability, lipophilicity, and cellular uptake in breast cancer cell lines. The [¹³¹I]I-AM was prepared by direct radiosynthesis with Chloramine-T method in two conditions (A: AM dissolved in NaOH, B: AM dissolved in ethanol). Reaction time, pH, and mass of the oxidizing agent were optimized as crucial parameters that affected the radiosynthesis reaction. Further analysis was conducted using the radiosynthesis conditions with the highest radiochemical purity (RCP). Stability tests were carried out at three storage conditions, including -20, 2, and 25 °C. A cellular uptake study was performed in T47D (breast cancer cell line) and Vero cells (noncancerous cell line) at various incubation times. The results show that the RCP values of [¹³¹I]I-AM under conditions A and B were 90.63 ± 0.44 and 95.17 ± 0.80% (n = 3), respectively. In the stability test, [¹³¹I]I-AM has an RCP above 90% after three days of storage at -20 °C. A significant difference was obtained between [¹³¹I]I-AM uptake in T47D and Vero cells. Based on these results, [¹³¹I]I-AM has been prepared with high RCP, stable at -20 °C, and specifically uptaken by breast cancer cell lines. Biodistribution evaluations in animals are recommended as further research in developing [¹³¹I]I-AM as a diagnostic and therapeutic agent for breast cancer.

Hyaluronic Acid-Coated Chitosan Nanoparticles as an Active Targeted Carrier of Alpha Mangostin for Breast Cancer Cells

Alpha mangostin (AM) has potential anticancer properties for breast cancer. This study aims to assess the potential of chitosan nanoparticles coated with hyaluronic acid for the targeted delivery of AM (AM-CS/HA) against MCF-7 breast cancer cells. AM-CS/HA showed a spherical shape with an average diameter of 304 nm, a polydispersity index of 0.3, and a negative charge of 24.43 mV. High encapsulation efficiency (90%) and drug loading (8.5%) were achieved. AM released from AM-CS/HA at an acidic pH of 5.5 was higher than the physiological pH of 7.4 and showed sustained release. The cytotoxic effect of AM-CS/HA (IC₅₀ 4.37 µg/mL) on MCF-7 was significantly higher than AM nanoparticles without HA coating (AM-CS) (IC₅₀ 4.48 µg/mL) and AM (IC₅₀ 5.27 µg/mL). These findings suggest that AM-CS/HA enhances AM cytotoxicity and has potential applications for breast cancer therapy.

Effects of Metformin Combined With Antifolates on HepG2 Cell Metabolism and Cellular Proliferation

Hepatocellular carcinoma (HCC), one of the most prevalent types of cancers worldwide, continues to maintain high levels of resistance to standard therapy. As clinical data revealed poor response rates, the need for developing new methods has increased to improve the overall wellbeing of patients with HCC. Furthermore, a growing body of evidence shows that cancer metabolic changes are a key feature of many types of human malignancies. Metabolic reprogramming refers to cancer cells’ ability to change their metabolism in order to meet the increased energy demand caused by continuous growth, rapid proliferation, and other neoplastic cell characteristics. For these reasons, metabolic pathways may become new therapeutic and chemopreventive targets. The aim of this study was to investigate the metabolic alterations associated with metformin (MET), an anti-diabetic agent when combined with two antifolate drugs: trimethoprim (TMP) or methotrexate (MTX), and how metabolic changes within the cancer cell may be used to increase cellular death. In this study, single drugs and combinations were investigated using in vitro assays including cytotoxicity assay (MTT), RT-qPCR, annexin V/PI apoptosis assay, scratch wound assay and Seahorse XF analysis, on a human HCC cell line, HepG2. The cytotoxicity assay showed that the IC₅₀ of MET as single therapy was 44.08 mM that was reduced to 22.73 mM and 29.29 mM when combined with TMP and MTX, respectively. The co-treatment of both drugs increased p53 and Bax apoptotic markers, while decreased the anti-apoptotic marker; Bcl-2. Both combinations increased the percentage of apoptotic cells and halted cancer cell migration when compared to MET alone. Furthermore, both combinations decreased the MET-induced increase in glycolysis, while also inducing mitochondrial damage, altering cancer cell bioenergetics. These findings provide an exciting insight into the anti-proliferative and apoptotic effects of MET and anti-folates on HepG2 cells, and how in combination, may potentially combat the aggressiveness of HCC.

Cytotoxic and Apoptotic Effect of Iris taochia Plant Extracts on Human Breast Cancer (MCF-7) Cells

Introduction:

Iris taochia is an endemic plant in Turkey. Iris species has many biological effects such as antibacterial, antiinflammatory, antioxidant and anticancer properties. Apoptosis is a programmed cell death and this mechanism regulates the death of cancer cells.

Purpose:

The aim of our work is to investigate how the Iris taochia extracts affect the apoptotic activity in the MCF7 cells.

Methods:

Cytotoxic dose and cell viability is determined by the MTT assay. Bad, Bax, Bcl-2, Bcl- W, Bid, Bim, Caspase 3, Caspase 8, CD40, CD40L, cIAP-2, CytoC, DR6, Fas, FasL, HSP27, HSP60, HSP70, HTRA, IGF-I, IGF-II, IGFBP-1, IGFBP-2, IGFBP-3, IGFBP-4, IGFBP-5, IGFBP-6, IGF-1sR, Livin, p21, p27, p53, SMAC, Survivin, sTNF-R1, sTNF-R2, TNF-α, TNF-β, TRAILR-1, TRAILR-2, TRAILR-3, TRAILR-4 and XIAP proteins were measured by the membrane array kit.

Results:

Iris taochia extracts exhibited significant cytotoxic effects on MCF7 cells and IC50 values ranging from 1.56 to 100 μg/mL. Our results indicate that MeOH extract of Iris taochia in MCF7 cells may be a regulator of cell death proteins, cell cycle and growth factors. DCM and EtOH extracts of Iris taochia have a limited effect on MCF7 cells, especially, HSPs, which play a significant role in chemoresistance, downregulating DCM and EtOH extracts of Iris taochia, whereas ligands and receptors of extrinsic apoptotic pathway are upregulated by these extracts.

Conclusion:

This is the first study to investigate the cytotoxic and apoptotic effect of Iris taochia extracts on MCF7 cells. Results also showed that Iris taochia reduced cell viability and induced apoptotic pathways as a potential regulator of cancer cell death.

The Most Competent Plant-Derived Natural Products for Targeting Apoptosis in Cancer Therapy

Cancer is a challenging problem for the global health community, and its increasing burden necessitates seeking novel and alternative therapies. Most cancers share six basic characteristics known as "cancer hallmarks", including uncontrolled proliferation, refractoriness to proliferation blockers, escaping apoptosis, unlimited proliferation, enhanced angiogenesis, and metastatic spread. Apoptosis, as one of the best-known programmed cell death processes, is generally promoted through two signaling pathways, including the intrinsic and extrinsic cascades. These pathways comprise several components that their alterations can render an apoptosis-resistance phenotype to the cell. Therefore, targeting more than one molecule in apoptotic pathways can be a novel and efficient approach for both identifying new anticancer therapeutics and preventing resistance to therapy. The main purpose of this review is to summarize data showing that various plant extracts and plant-derived molecules can activate both intrinsic and extrinsic apoptosis pathways in human cancer cells, making them attractive candidates in cancer treatment.

Bioactive Immunomodulatory Compounds: A Novel Combinatorial Strategy for Integrated Medicine in Oncology? BAIC Exposure in Cancer Cells

The Standardized Cultured Extract of Lentinula edodes Mycelia (also known as Active Hexose Correlated Compound, AHCC) and Wasabia japonica (Wasabi) are natural nutritional supplements known for their immunomodulatory and anticancer potential. The aim of this study was to evaluate the combinatorial effect of the bioactive immunomodulatory compound (BAIC), obtained by combining Wasabi and AHCC, on human breast (MCF-7) and pancreatic (Panc02) adenocarcinoma cell lines. Data obtained revealed that BAIC determines a striking decline in cancer cell growth at minimal concentrations compared with the use of Wasabi and AHCC as single agents. A significant increase in the G₀/G₁ subpopulation together with a marked augmentation in the percentage of apoptotic cells was demonstrated by flow cytometry, together with a significant upregulation in the expression of genes associated to the apoptotic cascade in both cell lines. The inhibitory role BAIC plays in mammospheres formation from MCF-7-derived cancer stem cells was shown with a marked reduction in size and number. Interestingly, when BAIC was exposed to monocytic cells, no cytotoxic effects were observed. A monocytes-to-macrophages differentiation was rather observed with the concomitant acquisition of an anti-inflammatory phenotype. Taken together, our findings suggest that BAIC could be used as a potential integration of standard chemotherapy treatments because of the improved inhibitory activity on cancer cell proliferation and reduced potential adverse effects.

Inhibition of human prostate cancer (PC-3) cells and targeting of PC-3-derived prostate cancer stem cells with koenimbin, a natural dietary compound from Murraya koenigii (L) Spreng

BACKGROUND

Inhibition of prostate cancer stem cells (PCSCs) is an efficient curative maintenance protocol for the prevention of prostate cancer. The objectives of this study were to assess the efficiency of koenimbin, a major biologically active component of Murraya koenigii (L) Spreng, in the suppression of PC-3 cells and to target PC-3-derived cancer stem cells (CSCs) through apoptotic and CSC signaling pathways in vitro.

MATERIALS AND METHODS

The antiproliferative activity of koenimbin was examined using MTT, and the apoptotic detection was carried out by acridine orange/propidium iodide (AO/PI) double-staining and multiparametric high-content screening (HCS) assays. Caspase bioluminescence assay, reverse transcription polymerase chain reaction (RT-PCR), and immunoblotting were conducted to confirm the expression of apoptotic-associated proteins. Cell cycle analysis was investigated using flow cytometry. Involvement of nuclear factor-kappa B (NF-κB) was analyzed using HCS assay. Aldefluor™ and prostasphere formation examinations were used to evaluate the impact of koenimbin on PC-3 CSCs in vitro.

RESULTS

Koenimbin remarkably inhibited cell proliferation in a dose-dependent manner. Koenimbin induced nuclear condensation, formation of apoptotic bodies, and G0/G1 phase arrest of PC-3 cells. Koenimbin triggered the activation of caspase-3/7 and caspase-9 and the release of cytochrome c, decreased anti-apoptotic Bcl-2 and HSP70 proteins, increased pro-apoptotic Bax proteins, and inhibited NF-κB translocation from the cytoplasm to the nucleus, leading to the activation of the intrinsic apoptotic pathway. Koenimbin significantly (P<0.05) reduced the aldehyde dehydrogenase-positive cell population of PC-3 CSCs and the size and number of PC-3 CSCs in primary, secondary, and tertiary prostaspheres in vitro.

CONCLUSION

Koenimbin has chemotherapeutic potential that may be employed for future treatment through decreasing the recurrence of cancer, resulting in the improvement of cancer management strategies and patient survival.

Beta-mangostin from Cratoxylum arborescens activates the intrinsic apoptosis pathway through reactive oxygen species with downregulation of the HSP70 gene in the HL60 cells associated with a G0/G1 cell-cycle arrest

Xanthones are phytochemical compounds found in a number of fruits and vegetables. Characteristically, they are noted to be made of diverse properties based on their biological, biochemical, and pharmacological actions. Accordingly, the apoptosis mechanisms induced by beta-mangostin, a xanthone compound isolated from Cratoxylum arborescens in the human promyelocytic leukemia cell line (HL60) in vitro, were examined in this study. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was done to estimate the cytotoxicity effect of β-mangostin on the HL60 cell line. Acridine orange/propidium iodide and Hoechst 33342 dyes and Annexin V tests were conducted to detect the apoptosis features. Caspase-3 and caspase-9 activities; reactive oxygen species; real-time polymerase chain reaction for Bcl-2, Bax, caspase-3, and caspase-9 Hsp70 genes; and western blot for p53, cytochrome c, and pro- and cleavage-caspase-3 and caspase-9 were assessed to examine the apoptosis mechanism. Cell-cycle analysis conducted revealed that β-mangostin inhibited the growth of HL60 at 58 µM in 24 h. The administration of β-mangostin with HL60 caused cell morphological changes related to apoptosis which increased the number of early and late apoptotic cells. The β-mangostin-catalyzed apoptosis action through caspase-3, caspase-7, and caspase-9 activation overproduced reactive oxygen species which downregulated the expression of antiapoptotic genes Bcl-2 and HSP70. Conversely, the expression of the apoptotic genes Bax, caspase-3, and caspase-9 were upregulated. Meanwhile, at the protein level, β-mangostin activated the formation of cleaved caspase-3 and caspase-9 and also upregulated the p53. β-mangostin arrested the cell cycle at the G0/G1 phase. Overall, the results for β-mangostin showed an antiproliferative effect in HL60 via stopping the cell cycle at the G0/G1 phase and prompted the intrinsic apoptosis pathway.

In vitro assessment of anti-proliferative effect induced by α-mangostin from Cratoxylum arborescens on HeLa cells

Natural medicinal products possess diverse chemical structures and have been an essential source for drug discovery. Therefore, in this study, α-mangostin (AM) is a plant-derived compound was investigated for the apoptotic effect on human cervical cancer cells (HeLa). The cytotoxic effects of AM on the viability of HeLa and human normal ovarian cell line (SV40) were evaluated by using MTT assay. Results showed that AM inhibited HeLa cells viability at concentration- and time-dependent manner with IC₅₀ value of 24.53 ± 1.48 µM at 24 h. The apoptogenic effects of AM on HeLa were assessed using fluorescence microscopy analysis. The effect of AM on cell proliferation was also studied through clonogenic assay. ROS production evaluation, flow cytometry (cell cycle) analysis, caspases 3/7, 8, and 9 assessment and multiple cytotoxicity assays were conducted to determine the mechanism of cell apoptosis. This was associated with G2/M phase cell cycle arrest and elevation in ROS production. AM induced mitochondrial apoptosis which was confirmed based on the significant increase in the levels of caspases 3/7 and 9 in a dose-dependent manner. Furthermore, the MMP disruption and increased cell permeability, concurrent with cytochrome c release from the mitochondria to the cytosol provided evidence that AM can induce apoptosis via mitochondrial-dependent pathway. AM exerted a remarkable antitumor effect and induced characteristic apoptogenic morphological changes on HeLa cells, which indicates the occurrence of cell death. This study reveals that AM could be a potential antitumor compound on cervical cancer in vitro and can be considered for further cervical cancer preclinical and in vivo testing.

Beta-mangostin demonstrates apoptogenesis in murine leukaemia (WEHI-3) cells in vitro and in vivo

Background

Beta-mangostin (BM) is a xanthone-type of natural compound isolated from Cratoxylum arborescens. This study aimed to examine the apoptosis mechanisms induced by BM in a murine monomyelocytic cell line (WEHI-3) in vitro and in vivo.

Methods

A WEHI-3 cell line was used to evaluate the cytotoxicity of BM by MTT. AO/PI and Hoechst 33342 dyes, Annexin V, multiparametric cytotoxicity 3 by high content screening (HCS); cell cycle tests were used to estimate the features of apoptosis and BM effects. Caspase 3 and 9 activities, ROS, western blot for Bcl2, and Bax were detected to study the mechanism of apoptosis. BALB/c mice injected with WEHI-3 cells were used to assess the apoptotic effect of BM in vivo.

Results

BM suppressed the growth of WEHI-3 cells at an IC₅₀value of 14 ± 3 μg/mL in 24 h. The ROS production was increased inside the cells in the treated doses. Both caspases (9 and 3) were activated in treating WEHI-3 cells at 24, 48 and 72 h. Different signs of apoptosis were detected, such as cell membrane blebbing, DNA segmentation and changes in the asymmetry of the cell membrane. Another action by which BM could inhibit WEHI-3 cells is to restrain the cell cycle at the G1/G0 phase. In the in vivo study, BM reduced the destructive effects of leukaemia on the spleen and liver by inducing apoptosis in leukaemic cells.

Conclusion

BM exerts anti-leukaemic properties in vitro and in vivo.

Pharmacology of mangostins and their derivatives: A comprehensive review

Mangosteen (Garcinia mangostana Linn.) is a well-known tropical tree indigenous to Southeast Asia. Its fruit's pericarp abounds with a class of isoprenylated xanthones which are referred as mangostins. Numerous in vitro and in vivo studies have shown that mangostins and their derivatives possess diverse pharmacological activities, such as antibacterial, antifungal, antimalarial, anticarcinogenic, antiatherogenic activities as well as neuroprotective properties in Alzheimer's disease (AD). This review article provides a comprehensive review of the pharmacological activities of mangostins and their derivatives to reveal their promising utilities in the treatment of certain important diseases, mainly focusing on the discussions of the underlying molecular targets/pathways, modes of action, and relevant structure-activity relationships (SARs). Meanwhile, the pharmacokinetics (PK) profile and recent toxicological studies of mangostins are also described for further druggability exploration in the future.

Apoptotic induction and inhibition of NF-κB signaling pathway in human prostatic cancer PC3 cells by natural compound 2,2'-oxybis (4-allyl-1-methoxybenzene), biseugenol B, from Litsea costalis: an in vitro study

Litsea is considered as an evergreen genus distributed in tropical and subtropical Asia; this genus belongs to the large family of Lauraceae. In this study, the cell-death metabolism of biseugenol B was investigated. Nuclear condensation, cell permeability, mitochondrial membrane potential (MMP) and release of cytochrome c have been detected in human prostate cancer cell line (PC3) treated with biseugenol B by high content screening (HCS). Fluorescent analysis was conducted to examine the reactive oxygen species formation. To determine the mechanism of cell death, the levels of Bcl-cell lymphoma (Bcl)-2 proteins, Bcl-2-associated X (Bax) protein and anti-apoptosis heat-shock protein 70 were tested by applying reverse transcription polymerase chain reaction and Western blot. Bioluminescent assays were also performed to assess the level of caspases such as 3/7, 8 and 9 during treatment. Furthermore, the involvement of nuclear factor kappa-B (NF-κB) was examined by Western blot and HCS. Biseugenol B showed significant cytotoxicity toward PC3 with no toxicity toward normal prostate cells (RWPE-1), which indicates that biseugenol B has qualities that induce apoptosis in tumor cells. The treatment of PC3 cells with biseugenol B provoked apoptosis with cell-death-transducing signals. Downregulation of Bcl-2 and upregulation of Bax regulated the MMP, which in turn caused the release of cytochrome c from mitochondria into cytosol. The release of cytochrome c activated caspase-9, which consequently activated caspase-3/7 with the cleaved poly(ADP-ribose) polymerase protein, thereby resulting in apoptosis alteration. Involvement of an extrinsic apoptosis pathway was exhibited by the increase in caspase-8, while the increase in caspase-3/7 and caspase-9 demonstrated involvement of an intrinsic apoptosis pathway. Meanwhile, no significant increase was observed in caspases 3/7, 8 or 9 in normal prostate cells (RWPE-1) after treatment with biseugenol B. Prevention of NF-κB translocation from the cytosol to the nucleus occurred in PC3 after treatment with biseugenol B. The results of our study reveal that biseugenol B triggers the apoptosis of PC3 cells via intrinsic and extrinsic apoptosis pathways and inhibition of NF-κB signaling pathway. Our findings suggest that biseugenol B is a potentially useful agent for prostate cancer treatment.

Anticancer activity of a monobenzyltin complex C1 against MDA-MB-231 cells through induction of Apoptosis and inhibition of breast cancer stem cells

In the present study, we examined the cytotoxic effects of Schiff base complex, [N-(3,5-dichloro-2-oxidobenzylidene)-4-chlorobenzyhydrazidato](o-methylbenzyl)aquatin(IV) chloride, and C1 on MDA-MB-231 cells and derived breast cancer stem cells from MDA-MB-231 cells. The acute toxicity experiment with compound C1 revealed no cytotoxic effects on rats. Fluorescent microscopic studies using Acridine Orange/Propidium Iodide (AO/PI) staining and flow cytometric analysis using an Annexin V probe confirmed the occurrence of apoptosis in C1-treated MDA-MB-231 cells. Compound C1 triggered intracellular reactive oxygen species (ROS) production and lactate dehydrogenase (LDH) releases in treated MDA-MB-231 cells. The Cellomics High Content Screening (HCS) analysis showed the induction of intrinsic pathways in treated MDA-MB-231 cells, and a luminescence assay revealed significant increases in caspase 9 and 3/7 activity. Furthermore, flow cytometric analysis showed that compound C1 induced G0/G1 arrest in treated MDA-MB-231 cells. Real time PCR and western blot analysis revealed the upregulation of the Bax protein and the downregulation of the Bcl-2 and HSP70 proteins. Additionally, this study revealed the suppressive effect of compound C1 against breast CSCs and its ability to inhibit the Wnt/β-catenin signaling pathways. Our results demonstrate the chemotherapeutic properties of compound C1 against breast cancer cells and derived breast cancer stem cells, suggesting that the anticancer capabilities of this compound should be clinically assessed.

Synergic Effect of α-Mangostin on the Cytotoxicity of Cisplatin in a Cervical Cancer Model

Cervical cancer is the second leading cause of death among Mexican women. The treatment with cis-diamminedichloroplatinum (II) (CDDP) has some serious side effects. Alpha-mangostin (α-M), has a protective effect against CDDP-induced nephrotoxicity, as well as antioxidant, antitumor, and anti-inflammatory properties. Hence, we explored the in vitro and in vivo effect of α-M on human cervical cancer cell proliferation when combined with CDDP. In vitro, The cytotoxic effect of α-M and/or CDDP was measured by the 3-(3,5-dimethylthiazol-2-yl)2,5-diphenyltetrazolium assay. Meanwhile, apoptosis, reactive oxygen species (ROS) production, and the cell cycle were determined with flow cytometry. For α-M+CDDP treatment, both a coincubation and preincubation scheme were employed. In vivo, xenotransplantation was performed in female athymic BALB/c (nu/nu) mice, and then tumor volume and body weight were measured weekly, whereas α-M interfered with the antiproliferative activity of CDDP in the coincubation scheme, with preincubation with α-M+CDDP showing significantly greater cytotoxicity than CDDP or α-M alone, significantly inhibiting average tumor volume and preventing nephrotoxicity. This effect was accompanied by increased apoptosis and ROS production by HeLa cervical cancer cells, as well as an arrest in the cell cycle. These results suggest that α-M may be useful as a neoadjuvant agent in cervical cancer therapy.

Metformin induces apoptosis via a mitochondria-mediated pathway in human breast cancer cells in vitro

Breast cancer is the most commonly occurring cancer and second leading cause of mortality in women. Metformin is a widely prescribed anti-hyperglycemic drug, which is emerging as a potential cancer preventative and treatment agent. However, the mechanisms underlying the suppressive effects of metformin on cancer cell growth and the induction of cancer cell apoptosis are not fully elucidated. The present study aimed to identify the pathways regulated by metformin in two breast cancer cell lines, MDA-MB-231 and MDA-MB-435. Cells were treated with various concentrations of metformin and then evaluated with respect to viability, proliferation, adenosine triphosphate (ATP) and reactive oxygen species (ROS) levels, mitochondrial membrane potential (∆ψm), and the expression of anti- and pro-apoptotic proteins. Metformin caused apoptosis in a concentration- and time-dependent manner, and decreased cell viability and ATP production. Furthermore, metformin induced the generation of ROS and decreased the ∆ψm. Moreover, metformin downregulated the expression of the anti-apoptotic proteins B-cell lymphoma 2 (BCL-2) and myeloid cell leukemia-1, and upregulated the expression of the pro-apoptotic BCL-2-associated X protein in MDA-MB-231 cells. These results demonstrate that the apoptotic and cytotoxic effects of metformin on breast cancer cells are mediated by the intrinsic mitochondria-mediated apoptosis pathway.

Metformin inhibits gastric cancer via the inhibition of HIF1α/PKM2 signaling

Recent evidence suggests that anti-diabetic drug metformin prevents cancer progression, but the mechanism by which metformin inhibits tumor growth remains elusive. In this study, we investigated the anticancer role of metformin in gastric cancer and explored the underlying mechanism. The expression of hypoxia inducible factor 1α (HIF1α) and pyruvate kinase M2 (PKM2) in different stages of gastric cancer tissues was detected by immunohistochemistry. Gastric cancer cell viability was evaluated by CCK-8 assay; apoptosis and cell cycle were analyzed by flow cytometry. The expression of PI3K, Akt, HIF1α, PARP, PKM2 and COX in gastric cancer cells was detected by immunofluorescence and Western blot analysis. We found that HIF1α and PKM2 protein expression levels were higher in advanced gastric cancer tissues than in gastritis tissues. Metformin reduced gastric cancer cell viability, invasion and migration. Metformin induced apoptosis and cell cycle arrest in part through inhibiting PARP expression. Metformin downregulated PI3K, Akt, HIF1α, PARP, PKM2 and COX expression. Moreover, overexpression of HIF1α increased gastric cancer cell viability, invasion and migration. In summary, metformin has profound antitumor effect for gastric cancer by inducing intrinsic apoptosis via the inhibition of HIF1α/PKM2 signaling pathway.

Koenimbin, a natural dietary compound of Murraya koenigii (L) Spreng: inhibition of MCF7 breast cancer cells and targeting of derived MCF7 breast cancer stem cells (CD44(+)/CD24(-/low)): an in vitro study

BACKGROUND

Inhibition of breast cancer stem cells has been shown to be an effective therapeutic strategy for cancer prevention. The aims of this work were to evaluate the efficacy of koenimbin, isolated from Murraya koenigii (L) Spreng, in the inhibition of MCF7 breast cancer cells and to target MCF7 breast cancer stem cells through apoptosis in vitro.

METHODS

Koenimbin-induced cell viability was evaluated using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Nuclear condensation, cell permeability, mitochondrial membrane potential, and cytochrome c release were observed using high-content screening. Cell cycle arrest was examined using flow cytometry, while human apoptosis proteome profiler assays were used to investigate the mechanism of apoptosis. Protein expression levels of Bax, Bcl2, and heat shock protein 70 were confirmed using Western blotting. Caspase-7, caspase-8, and caspase-9 levels were measured, and nuclear factor kappa B (NF-κB) activity was assessed using a high-content screening assay. Aldefluor™ and mammosphere formation assays were used to evaluate the effect of koenimbin on MCF7 breast cancer stem cells in vitro. The Wnt/β-catenin signaling pathway was investigated using Western blotting.

RESULTS

Koenimbin-induced apoptosis in MCF7 cells was mediated by cell death-transducing signals regulating the mitochondrial membrane potential by downregulating Bcl2 and upregulating Bax, due to cytochrome c release from the mitochondria to the cytosol. Koenimbin induced significant (P<0.05) sub-G0 phase arrest in breast cancer cells. Cytochrome c release triggered caspase-9 activation, which then activated caspase-7, leading to apoptotic changes. This form of apoptosis is closely associated with the intrinsic pathway and inhibition of NF-κB translocation from the cytoplasm to the nucleus. Koenimbin significantly (P<0.05) decreased the aldehyde dehydrogenase-positive cell population in MCF7 cancer stem cells and significantly (P<0.01) decreased the size and number of MCF7 cancer stem cells in primary, secondary, and tertiary mammospheres in vitro. Koenimbin also significantly (P<0.05) downregulated the Wnt/β-catenin self-renewal pathway.

CONCLUSION

Koenimbin has potential for future chemoprevention studies, and may lead to the discovery of further cancer management strategies by reducing cancer resistance and recurrence and improving patient survival.