Targeting apoptosis pathways in cancer and perspectives with natural compounds from mother nature

Nutraceuticals and "Repurposed" Drugs of Phytochemical Origin in Prevention and Interception of Chronic Degenerative Diseases and Cancer

BACKGROUND

Chronic, degenerative diseases are often characterized by inflammation and aberrant angiogenesis. For these pathologies, including rheumatoid arthritis, cardiovascular and autoimmune diseases, cancer, diabetes, and obesity, current therapies have limited efficacy.

OBJECTIVES

The validation of novel (chemo)preventive and interceptive approaches, and the use of new or repurposed agents, alone or in combination with registered drugs, are urgently required.

RESULTS

Phytochemicals (triterpenoids, flavonoids, retinoids) and their derivatives, nonsteroidal anti-inflammatory drugs (aspirin) as well as biguanides (metformin and phenformin) originally developed from phytochemical backbones, are multi-target agents showing antiangiogenic and anti-anti-inflammatory proprieties. Many of them target AMPK and metabolic pathways such as the mTOR axis. We summarize the beneficial effects of several compounds in conferring protection and supporting therapy, and as a paradigm, we present data on terpenoids & biquanides on beer hop xanthohumol and hydroxytryrosol from olive mill waste waters.

CONCLUSIONS

These molecules could be employed for combinatorial chemoprevention and interception approaches or chemoprevention/therapy regimens for cancer and other chronic complex diseases.

Apoptotic effect of green synthesized gold nanoparticles from Curcuma wenyujin extract against human renal cell carcinoma A498 cells

Introduction: Curcuma wenyujin is a plant which belongs to the family of Zingiberaceae, found in South Asia and China. C. wenyujin is a major constituent in Chinese traditional medicine and is used to treat liver diseases, blood clots, and is also prescribed as a painkiller. C. wenyujin possesses antioxidant, antiproliferative, and antitumorogenic properties, and many researchers have proved the efficacy of C. wenyujin against various types of cancer. The major drawback of this historical drug is it's low bioavailability. Methods: This study synthesized gold nanoparticles using C. wenyujin and assessed its potency against in vitro renal cancer cells. The biosynthesized C. wenyujin gold nanoparticles (CWAuNPs) were characterized using UV-Spec, DLS, FTIR, SAED, TEM, EDAX, and Atomic Force analysis. The cytotoxicity of CWAuNPs against renal cancer cell lines A498 and SW-156 was assessed with MTT assay. The induction of apoptosis by CWAuNPs in A498 cell was measured using apoptotic staining DAPI, Rhodamine 123, and H2DCFDA. The apoptotic activity of CWAuNPs was further confirmed with flow cytometric analysis. The molecular mechanism of CWAuNPs was analyzed with qPCR and immunoblotting analysis of caspases, proapoptotic, and antiapoptotic proteins. Results: The characterization of results of synthesized CWAuNPs satisfy the distinctive properties of a potent nanodrug. The results of apoptotic staining techniques confirm the induction of CWAuNPs in A498 by increasing the apoptotic Caspase 3,9, Bid, and Bad, and decreasing the antiapoptotic protein Bcl-2, Bcl-xl expressions, which is authentically proven by the qPCR and immunoblotting analysis. Conclusion: In conclusion, these results confirmed that biosynthesized CWAuNPs is a potent anticancer agent which induces apoptosis in the A498 renal carcinoma cell line.

A novel herbometallic nanodrug has the potential for antibacterial and anticancer activity through oxidative damage

Aim: Preparation of a herbometallic nano-drug, Rasa Manikya nanoparticle (RMNP) and investigation of its antimicrobial, and anticancer activity. Materials & methods: Physicochemical characterizations of RMNP were performed using different analytical methods. The antimicrobial and anticancer potential of RMNPs were assessed by an in vitro cellular assay. Bacterial cell wall lysis was observed by field emission scanning electron microscopy and mitochondrial metabolism alteration factor was measured via standard method. Results: Physicochemical analysis confirmed that RMNP was rich in mineral constituents. Synergistic effect of RMNPs enhanced lysis of bacterial peptidoglycan layers and impaired cellular redox balance, GSH/NADPH level followed by induction of cell apoptosis. Conclusion: The present study confirms that RMNP can be used as a dual therapeutic option for combating drug-resistant microbial strains and breast cancer.

Secondary metabolite profiling, cytotoxicity, anti-inflammatory potential and in vitro inhibitory activities of Nardostachys jatamansi on key enzymes linked to hyperglycemia, hypertension and cognitive disorders

ETHNOPHARMACOLOGICAL RELEVANCE

Nardostachys jatamansi (D. Don) DC., 'Spikenard' or 'Jatamansi', a highly valued, aromatic herb from alpine Himalayas has a long history of use as ethnomedicine and dietary supplements in Ayurveda, Unani and Chinese system of medicine since Vedic ages (1000-800 BC). In Ayurveda and traditional system of medicine, the species is used as stimulant, sedative, brain tonic or mind rejuvenator, antidiabetic, cardio tonic, and in the treatment of various neurological disorders such as insomnia, epilepsy, hysteria, anxiety and depression. It is considered as Sattvic herb in Ayurveda and is now commercially marketed either as single or poly-herbal formulations by many companies in national and international markets.

AIM OF THE STUDY

The species has become threatened in its natural habitats due to over exploitation and illegal trade of its rhizomes for drug preparation in herbal and pharmaceutical industries. Considering the increasing demand and tremendous medicinal importance of this threatened plant species, a detailed study was undertaken to evaluate its antioxidant potential, secondary metabolite profiling, cytotoxicity, anti-inflammatory potential and in vitro enzyme inhibitory activities on key enzymes linked to hyperglycemia, hypertension and cognitive disorders in different plant parts of wild and in vitro-raised plants with respect to different solvent systems for its sustainable utilization.

MATERIALS AND METHODS

Anti-cholinesterase activity of leaves and rhizome of wild and cultured plant extracts was investigated against both acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) enzymes. In vitro anti-hyperglycemic (α-amylase and PTP1B), anti-hypertensive (angiotensin-converting enzyme), anti-tyrosinase and anti-inflammatory potential (5-lipoxygenase and hyaluronidase) of different plant parts of wild and in vitro-raised plants with respect to different solvent systems were also evaluated. In vitro cytotoxic effect of rootstock extracts of wild and in vitro-derived plants were against cancer (HCT-116, MCF-7 and OE33) and two normal (HEK and MEF) cell lines. Secondary metabolite profiling of rhizome segments of wild and in vitro-derived plants was carried out by quantitative gas chromatography-mass spectrometry (GC-MS).

RESULTS

In vitro-raised plantlets showed comparative higher yield of various secondary metabolites with a significantly high antioxidant activity as compared to the wild plants. Methanolic rootstock extracts of both wild and in vitro-derived plants of N. jatamansi exhibited significant AChE (IC₅₀ 36.46 ± 2.1 and 31.18 ± 2.6 µg/ml, respectively) and BuChE (IC₅₀ 64.6 ± 3.5 and 60.12 ± 3.6 µg/ml, respectively) inhibitory potential as compared to standard inhibitor galanthamine (IC₅₀ 0.94 ± 0.03 and 4.45 ± 0.5 µg/ml). Methanolic rootstock extract of in vitro-derived plants showed significant α-amylase (IC₅₀ 90.69 ± 2.1 µg/ml), PTP1B (IC₅₀ 24.56 ± 0.8 µg/ml), angiotensin-converting enzyme (IC₅₀ 42.5 ± 3.6 µg/ml) and tyrosinase (IC₅₀ 168.12 ± 3.6 µg/ml) inhibitory potential as compared to standard acarbose (IC₅₀ 52.36 ± 3.1 µg/ml), ursolic acid (IC₅₀ 5.24 ± 0.8 µg/ml), captopril (IC₅₀ 32.36 ± 2.5 µg/ml) and kojic acid (IC₅₀ = 54.44 ± 2.3 µg/ml). Both the methanolic rootstock and leaf extracts of tissue culture-derived plants exhibited promising anti-5-LOX and anti-hyaluronidase activities against the known inhibitor of 5-LOX and hyaluronidase. Furthermore, methanolic rootstock extracts of both wild and in vitro-derived plants exhibited promising cytotoxic effects to HCT-116, MCF-7 and OE33 cell lines as compared to the normal HEK and MEF after 12 h of treatment. Secondary metabolite profiling of wild and in vitro-derived plants by quantitative GC-MS analysis revealed the presence of different classes of terpenoids and phenolic acids might be responsible for its effective biological activities.

CONCLUSION

In vitro-derived plants revealed a substantial anti-cholinesterases, anti-hyperglycemic anti-inflammatory, anti-hypertensive and anti-tyrosinase potential with higher yield of various bioactive metabolites and significantly higher antioxidant activity which substantially explain medicinal importance of N. jatamansi in traditional medicine, used for centuries in different Ayurvedic formulations. The present findings suggest that cultured plants could be a promising alternative for the production of bioactive metabolites with comparative biological activities to the wild plants.

An Olive Leaf Extract Rich in Polyphenols Promotes Apoptosis in Cervical Cancer Cells by Upregulating p21Cip/WAF1 Gene Expression

Most of the common drugs used to treat the cervical cancer, which main etiological factor is the HPV infection, cause side effects and intrinsic/acquired resistance to chemotherapy. In this study we investigated whether an olive leaf extract (OLE), rich in polyphenols, was able to exert anti-tumor effects in human cervical cancer cells (HeLa). MTT assay results showed a reduction of HeLa cells viability OLE-induced, concomitantly with a gene and protein down-regulation of Cyclin-D1 and an up-regulation of p21, triggering intrinsic apoptosis. OLE reduced NFkB nuclear translocation, which constitutive activation, stimulated by HPV-oncoproteins, promotes cancer progression and functional studies revealed that OLE activated p21^Cip/WAF1 in a transcriptional-dependent-manner, by reducing the nuclear recruitment of NFkB on its responsive elements. Furthermore, OLE treatment counteracted epithelial-to-mesenchymal-transition and inhibited anchorage-dependent and -independent cell growth EGF-induced. Finally, MTT assay results revealed that OLE plus Cisplatin strengthened the reduction of cells viability Cisplatin-induced, as OLE inhibited NFkB, AkT and MAPK pathways, all involved in Cisplatin chemoresistance. In conclusion, we demonstrated that in HeLa cells OLE exerts pro-apoptotic effects, elucidating the molecular mechanism and that OLE could mitigate Cisplatin chemoresistance. Further studies are needed to explore the potential coadiuvant use of OLE for cervical cancer treatment.

β-Sitosterol and Gemcitabine Exhibit Synergistic Anti-pancreatic Cancer Activity by Modulating Apoptosis and Inhibiting Epithelial-Mesenchymal Transition by Deactivating Akt/GSK-3β Signaling

β-sitosterol (BS), a major bioactive constituent present in plants, has shown potent anti-cancer activity against many human cancer cells, but its activity in pancreatic cancer (PC) cells has rarely been reported. Gemcitabine (GEM) is one of the first-line drugs for PC therapy, however, the treatment effect is not sustained due to prolonged drug resistance. In this study, we firstly studied the anti-PC activity and the mechanism of BS alone and in combination with GEM in vitro and in vivo. BS effectively inhibited the growth of PC cell lines by inhibiting proliferation, inducing G0/G1 phase arrest and apoptosis, suppressed the NF- kB activity, and increased expression of the protein Bax but decreased expression of the protein Bcl-2. Moreover, BS inhibited migration and invasion and downregulated epithelial–mesenchymal transition (EMT) markers and AKT/GSK-3β signaling pathways. Furthermore, the combination of BS and GEM exhibited a significant synergistic effect in MIAPaCa-2 and BXPC-3 cells. More importantly, the combined treatment with BS and GEM lead to significant growth inhibition of PC xenografts. Overall, our data revealed a promising treatment option for PC by the combination therapy of BS and GEM.

Expression of P53, BAX, and BCL-2 in human malignant melanoma and squamous cell carcinoma cells after tea tree oil treatment in vitro

Tea tree oil (TTO) is an essential oil obtained by steam distillation from the leaves of Melaleuca alternifolia (Myrtaceae). This oil has traditionally been used for the treatment of various skin infections. The present study aimed to investigate the cytotoxic effects of TTO against two representative types of human skin cancer, namely malignant melanoma (A-375) and squamous cell carcinoma (HEp-2).To outline the basic molecular mechanism involved in apoptosis induction in A-375 and HEp-2 cell lines, Annexin V/PI staining for apoptosis detection, cell cycle analysis were monitored using flow cytometry and mRNA expression levels of the apoptosis-regulatory genes P53, BAX, and BCL-2 were determined by real-time PCR and western blot after treatment with TTO. Results showed that TTO exhibited a strong cytotoxicity towards A-375 and HEp-2 cell lines, with IC50 values of 0.038% (v/v) and 0.024% (v/v) respectively. This cytotoxicity resulted from TTO induced apoptosis in both A-375 and HEp-2 cell lines as evidenced by morphological features of apoptosis and Annexin V/PI staining results in addition to the activation of caspase-3/7 and -9, upregulation of pro-apoptotic genes (P53 and BAX) and downregulation of the anti-apoptotic gene BCL-2. Additionally, cell cycle analysis showed that TTO caused cell cycle arrest mainly at G2/M phase. Taken together, the results of this study reveal that TTO is an effective apoptosis inducer in A-375 and HEp-2 cancer cell lines, indicating that it could be a promising chemopreventive candidate to be used in topical formulations against melanoma and squamous cell cancers; however, further in vivo studies may be warranted.

Synthesis of Cucurbitacin B Derivatives as Potential Anti-Hepatocellular Carcinoma Agents

Cucurbitacin B shows potent activity against tumor cells, but its high toxicity limits its application in the clinic. A series of cucurbitacin B derivatives was synthesized and evaluated for their anti-hepatocellular carcinoma (HCC) activities against the HepG-2 cell line. These compounds were also tested for their toxicity against the L-O2 normal cell line. The compound with the most potential, 10b, exhibited potent activity against the HepG-2 cell line with an IC50 value of 0.63 μM. Moreover, compound 10b showed the highest TI value (4.71), which is a 14.7-fold improvement compared to its parent compound cucurbitacin B. A preliminary molecular mechanism study of 10b indicated that 10b could inhibit P-STAT3 to induce the activation of mitochondrial apoptotic pathways. An in vivo acute toxicity study indicated that the compound 10b has preferable safety and tolerability compared with cucurbitacin B. These findings indicate that compound 10b might be considered as a lead compound for exploring effective anti-HCC drugs.

Rhazyaminine from Rhazya stricta Inhibits Metastasis and Induces Apoptosis by Downregulating Bcl-2 Gene in MCF7 Cell Line

Background: The role of alkaloids isolated from Rhazya stricta Decne (Apocynaceae family) (RS) in targeting genes involved in cancer and metastasis remains to be elucidated. Objective: Identify and characterize new compounds from RS, which inhibit gene(s) involved in the survival, invasion, self-renewal, and metastatic processes of cancer cells. Methods: Bioinformatics study was performed using HISAT2, stringtie, and ballgown pipeline to understand expressional differences between a normal epithelial cell line-MCF10A and MCF7. NMR and ATR-FTIR were performed to elucidate the structure of rhazyaminine (R.A), isolated from R stricta. Cell viability assay was performed using 0, 25, and 50 μg/mL of total extract of R stricta (TERS) and R.A, respectively, for 0, 24, and 48 hours, followed by scratch assay. In addition, total RNA was isolated for RNA-seq analysis of MCF7 cell line treated with R.A followed by qRT-PCR analysis of Bcl-2 gene. Results: Deptor, which is upregulated in MCF7 compared with MCF10A as found in our bioinformatics study was downregulated by R.A. Furthermore, R.A effectively reduced cell viability to around 50% (P < .05) and restricted cell migration in scratch assay. Thirteen genes, related to metastasis and cancer stem cells, were downregulated by R.A according to RNA-seq analysis. Additionally, qRT-PCR validated the downregulation of Bcl-2 gene in R.A-treated cells by less than 0.5 folds (P < .05). Conclusion: R.A successfully downregulated key genes involved in apoptosis, cell survival, epithelial-mesenchymal transition, cancer stem cell proliferation, and Wnt signal transduction pathway making it an excellent “lead candidate” molecule for in vivo proof-of-concept studies.

Reactive Oxygen Species and p53 Mediated Activation of p38 and Caspases is Critically Involved in Kaempferol Induced Apoptosis in Colorectal Cancer Cells

Here the molecular mechanisms of Kaempferol were examined in colorectal cancers (CRCs). Kaempferol significantly exerted antiproliferative and cytotoxic effect in HCT116, HCT15, and SW480 cells. Also, Kaempferol increased sub G1 population, G2/M arrest, and the numbers of TUNEL cells in HCT116 colorectal cancer cells. Also, Kaempferol increased the PARP cleavages and activation of caspase-8, -9, and -3, phospho-p38 MAPK, p53, and p21 in HCT116 and HCT15 cells. Of note, Kaempferol generated reactive oxygen species (ROS) (43.7 ± 0.56 vs 25.8 ± 0.43, P < 0.01) in HCT116 cells and reversely ROS inhibitor NAC obstructed the effects of Kaempferol to cleave PARP and caspase-3 and activate phosphorylation of p38 MAPK in HCT116 colorectal cancer cells. Likewise, pancaspase inhibitor z-vad-fmk, p38 MAPK inhibitor SB203580, and p53 depletion blocked PARP and caspase-3 in Kaempferol treated HCT116 colorectal cancer cells. Therefore, these findings provide novel insight that ROS and p53 signalings mediate p38 phosphorylation and caspase activation in Kaempferol stimulated apoptosis in CRCs.

Inhibition of Wnt3a/FOXM1/β-Catenin Axis and Activation of GSK3β and Caspases are Critically Involved in Apoptotic Effect of Moracin D in Breast Cancers

Although Moracin D derived from Morus alba was known to have anti-inflammatory and antioxidant activities, the underlying antitumor mechanism of Moracin D has not been unveiled thus far. Thus, in the recent study, the apoptotic mechanism of Moracin D was elucidated in breast cancer cells. Herein, Moracin D exerted significant cytotoxicity in MDA-MB-231 and MCF-7 cells. Furthermore, Moracin D increased sub G1 population; cleaved poly (Adenosine diphosphate (ADP-ribose)) polymerase (PARP); activated cysteine aspartyl-specific protease 3 (caspase 3); and attenuated the expression of c-Myc, cyclin D1, B-cell lymphoma 2 (Bcl-2), and X-linked inhibitor of apoptosis protein (XIAP) in MDA-MB231 cells. Of note, Moracin D reduced expression of Forkhead box M1 (FOXM1), β-catenin, Wnt3a, and upregulated glycogen synthase kinase 3 beta (GSK3β) on Tyr216 along with disturbed binding of FOXM1 with β-catenin in MDA-MB-231 cells. Conversely, GSK3β inhibitor SB216763 reversed the apoptotic ability of Moracin D to reduce expression of FOXM1, β-catenin, pro-caspase3, and pro-PARP in MDA-MB-231 cells. Overall, these findings provide novel insight that Moracin D inhibits proliferation and induces apoptosis via suppression of Wnt3a/FOXM1/β-catenin signaling and activation of caspases and GSK3β.

TTB2 induces apoptosis in Ewing sarcoma cells

A steroidal saponin named pennogenin 3-O-α-L-rhamnopyranosyl-(1→2) [α-L-rhamnopyranosyl-(1→4)]-β-D-glucoyranoside(TTB2) has been successfully separated from the n-BuOH extracts of Trillium tschonoskii Maxim and is able to induce cytotoxicity to some types cancer cells. The present study aimed to investigate how this novel saponinin duces cytotoxicity in malignant sarcoma cells and to clarify its molecular mechanisms of action. It was determined this steroidal saponin induced the apoptosis in Rh1 cells and activated caspase-3 and caspase-9. Additionally, it disrupted the mitochondrial membrane potential and altered the expression of bax and bcl-2. Thus, the results of present study identified that an anticancer saponin isolated from Trillium tschonoskii Maxim may be developed as a potential novel therapeutic strategy to treat certain types of cancer, including lung cancer and lung sarcoma.

Magnolol: A Neolignan from the Magnolia Family for the Prevention and Treatment of Cancer

The past few decades have witnessed widespread research to challenge carcinogenesis; however, it remains one of the most important health concerns with the worst prognosis and diagnosis. Increasing lines of evidence clearly show that the rate of cancer incidence will increase in future and will create global havoc, designating it as an epidemic. Conventional chemotherapeutics and treatment with synthetic disciplines are often associated with adverse side effects and development of chemoresistance. Thus, discovering novel economic and patient friendly drugs that are safe and efficacious is warranted. Several natural compounds have proved their potential against this dreadful disease so far. Magnolol is a hydroxylated biphenyl isolated from the root and stem bark of Magnolia tree. Magnolol can efficiently prevent or inhibit the growth of various cancers originating from different organs such as brain, breast, cervical, colon, liver, lung, prostate, skin, etc. Considering these perspectives, the current review primarily focuses on the fascinating role of magnolol against various types of cancers, and the source and chemistry of magnolol and the molecular mechanism underlying the targets of magnolol are discussed. This review proposes magnolol as a suitable candidate that can be appropriately designed and established into a potent anti-cancer drug.

Asteriscus graveolens Extract in Combination with Cisplatin/Etoposide/Doxorubicin Suppresses Lymphoma Cell Growth through Induction of Caspase-3 Dependent Apoptosis

Chemotherapy drugs action against cancer is not selective, lead to adverse reactions and drug resistance. Combination therapies have proven more effective in defeating cancers. We hypothesize that plant extract/fraction contains many/several compounds and as such can target multiple pathways as cytotoxic agent and may also have chemo sensitizing activities. We designed a study in which, Asteriscus graveolens (Forssk.) Less (A. graveolens)-derived fraction that contains sesquiterpene lactone asteriscunolide isomers (AS) will be tested in combination with known chemotherapy drugs. Successful combination will permit to reduce chemotherapy drugs concentration and still get the same impact on cancer cells. Sesquiterpene lactone such as asteriscunolide isomers is a naturally occurring compound found in a variety of fruits, vegetables, and medicinal plants with anti-cancer properties. The experiments presented here showed that adding plant fraction containing AS permit reducing the concentration of cisplatin/etoposide/doxorubicin in order to reduce mouse BS-24-1 lymphoma cells (BS-24-1 cells) survival. It involved enhancing the production of Reactive Oxygen Species (ROS), activation of caspase-3 and inhibition of Topoisomerase I activity. Taken together, the results suggest that A. graveolens fraction sensitized BS-24-1 cells to cisplatin/etoposide/doxorubicin through induction of ROS and caspase-3-dependent apoptosis.

Sorbus commixta water extract induces apoptotic cell death via a ROS-dependent pathway

The stembark of Sorbus commixta Hedl. has been used for treating asthma, bronchitis, gastritis and edema. However, the anticancer and proapoptotic effects of the water extract of the stembark of S. commixta (SCE) remain unknown. In the present study, it was shown that SCE inhibited the cell viability of the hepatocellular carcinoma cell lines Hep3B and HepG2, and of the colon carcinoma cell line HCT116. DNA content analysis indicated that SCE increased the sub-G1 population of HCT116 cells. In addition, degradation of nuclear DNA and levels of proapoptotic cascade components, including caspase-9, caspase-3 and poly ADP-ribose polymerase, were augmented by SCE treatment. Mitochondrial membrane potential and the ratio of B-cell lymphoma-2 (Bcl-2)/Bcl-2-associated X protein (Bax) were also reduced. Furthermore, SCE increased the expression of proapoptotic proteins, including p21, p27 and p53. Mouse double minute 2 homology, a negative regulator of p53, was cleaved by SCE treatment. Intracellular reactive oxygen species (ROS) production was also increased by SCE treatment. However, the SCE-induced cytotoxic effects and the increased expression of proapoptotic proteins, including p53 and p21, and reduced Bcl-2/Bax ratio, could be attenuated by N-acetyl cysteine, an ROS inhibitor. Taken together, these results indicate that SCE is a potent proapoptotic herbal medicine, which exerts its effects via the ROS-mediated mitochondrial pathway.

Apoptotic effect of lambertianic acid through AMPK/FOXM1 signaling in MDA-MB231 breast cancer cells

Though lambertianic acid (LA) was known to exert antitumor effect in liver and prostate cancers, its underlying anticancer mechanism is never reported in breast cancers so far. Thus, in this study, apoptotic mechanism of LA was elucidated in MDA-MB-231 breast cancer cells. Here, LA increased cytotoxicity in MCF-7 and MDA-MB-231 cells; enhanced sub-G1 population, G2/M arrest, and cleaved poly(ADP-ribose) polymerase; activated phosphorylation of AMP-activated protein kinase (AMPK)/acetyl-CoA carboxylase pathway; and also suppressed phosphorylation of AKT and the expression of forkhead box M1 (FOXM1), X-linked inhibitor of apoptosis protein, B-cell lymphoma 2, and CyclinB1 in MDA-MB-231 cells. Furthermore, AMPK inhibitor compound C reversed the effect of LA on FOXM1, Cyclin B1, and cleaved poly(ADP-ribose) polymerase in MDA-MB-231 cells. Notably, immunoprecipitation revealed that LA disturbed the direct binding of AKT and FOXM1 in MDA-MB-231 cells. Overall, these findings suggest that LA-induced apoptosis is mediated via activation of AMPK and inhibition of AKT/FOXM1 signaling pathway.

Tubeimoside-1, Triterpenoid Saponin, as a Potential Natural Cancer Killer

Nature, an expert craftsman of molecules, has generated extensive array of bioactive molecular entities. It persists as an inexhaustible resource for discovery of drugs and supplied enormous scaffold diversification for development into effectual drugs to treat multiple pathological conditions. This review provides an update on the sources, biological, and pharmacological effects of nature's gift, a triterpenoid saponin, tubeimoside-1 which is a major bioactive constituent of the bulb of Bolbostemma paniculatum. Tubeimoside-1 is known to possess various pharmacological properties such as anti-cancer, anti-HIV, and anti-inflammatory. Recently, anti-proliferative potential of tubeimoside-1 has been widely studied. The present review article seeks to cover the recent developments of tubeimoside-1′s pharmacological position in the arena of herbal drugs, providing an insight into its current status in therapeutic pursuits. This anti-cancer triterpenoid saponin fight cancer progression by induction of apoptosis, cell cycle arrest, and inhibiting metastasis by specifically targeting multiple signaling pathways those are usually deregulated in various cancers. The reported data recommend tubeimoside-1′s mutitarget activity in preference to single effect that may perform an imperative role towards developing tubeimoside-1 into potential pharmacological drug.

Anticancer Effects of Gingerol in Retinoblastoma Cancer Cells (RB355 Cell Line) Are Mediated via Apoptosis Induction, Cell Cycle Arrest and Upregulation of PI3K/Akt Signaling Pathway

Background

The main aim of the current investigation was to study the antiproliferative activity of gingerol in RB355 human retinoblastoma cancer cells. The effects of gingerol on apoptosis induction, cell cycle arrest, and PI3K/Akt signaling pathway were also evaluated.

Material/Methods

MTT cell viability assay was used to assess the cytotoxic effects of gingerol in these cells while. To study apoptotic effects in these cells, we used inverted microscopy along with fluorescence microscopy using acridine orange/propidium iodide and Hoechst 33258 as staining dyes. Flow cytometry was used to study cell cycle phase distribution and Western blot assay indicated effects on PI3K/Akt protein expression levels.

Results

Results showed that gingerol exerted dose-dependent and time-dependent growth inhibitory effects in these retinoblastoma cells. However, the growth inhibitory effects of gingerol were less pronounced against normal fr2 cells. As compared to the untreated control cells, gingerol-treated cells at concentrations of 25, 75, and 150 μM had drastic changes in cell morphology, including rounding and withering of cells, with disorganized cell layers. Gingerol-treated cells exhibited bright fluorescence, indicating rupture of the cell membrane. These results were further confirmed by acridine orange/propidium iodide staining, in which untreated cells showed normal green fluorescence and gingerol-treated cells showed yellow/red fluorescence. Gingerol also led to dose-dependent G2/M phase cell cycle arrest in RB355 retinoblastoma cells, as well as concentration-dependent activation of PI3K-related protein expressions.

Conclusions

Gingerol exhibits potent anticancer effects in RB355 human retinoblastoma cancer cells and these effects were mediated via apoptosis induction, cell cycle arrest, and modulation of the PI3K/Akt signaling pathway.

Anti-Cancer Activities of Diterpenoids Derived from Euphorbia fischeriana Steud

Euphorbia fischeriana Steud is an essential oriental folk medicine used for healing cancer, edema and tuberculosis. Recently, its anticancer activitity has attracted more attention. A volume of research has indicated that diterpenoids are the major anticancer active constituents from this medicinal herb. In this review, we aimed to provide a summary of the promising anticancer diterpenoids from this plant; many diterpenoids mentioned in this article are newly discovered diterpenoids. According to the carbon skeleton and substituents, they can be classified into eight subtypes: ent-abietane, daphnane, tigliane, ingenane, ent-atisane, ent-rosane, ent-kaurane, and lathyrane. Futhermore, their key anticancer mechanisms and protein targets of these compounds will be discussed. These natural diterpenoids could provide a reservoir for drug discovery.

Metabolomics profiles delineate uridine deficiency contributes to mitochondria-mediated apoptosis induced by celastrol in human acute promyelocytic leukemia cells

Celastrol, extracted from “Thunder of God Vine”, is a promising anti-cancer natural product. However, its effect on acute promyelocytic leukemia (APL) and underlying molecular mechanism are poorly understood. The purpose of this study was to explore its effect on APL and underlying mechanism based on metabolomics. Firstly, multiple assays indicated that celastrol could induce apoptosis of APL cells via p53-activated mitochondrial pathway. Secondly, unbiased metabolomics revealed that uridine was the most notable changed metabolite. Further study verified that uridine could reverse the apoptosis induced by celastrol. The decreased uridine was caused by suppressing the expression of gene encoding Dihydroorotate dehydrogenase, whose inhibitor could also induce apoptosis of APL cells. At last, mouse model confirmed that celastrol inhibited tumor growth through enhanced apoptosis. Celastrol could also decrease uridine and DHODH protein level in tumor tissues. Our in vivo study also indicated that celastrol had no systemic toxicity at pharmacological dose (2 mg/kg, i.p., 21 days). Altogether, our metabolomics study firstly reveals that uridine deficiency contributes to mitochondrial apoptosis induced by celastrol in APL cells. Celastrol shows great potential for the treatment of APL.

Medicinal Plants from Near East for Cancer Therapy

Background: Cancer is one of the major problems affecting public health worldwide. As other cultures, the populations of the Near East rely on medicinal herbs and their preparations to fight cancer. Methods: We compiled data derived from historical ethnopharmacological information as well as in vitro and in vivo results and clinical findings extracted from different literature databases including (PubMed, Scopus, Web of Science, and Google Scholar) during the past two decades. Results: In this survey, we analyzed the huge amount of data available on anticancer ethnopharmacological sources used in the Near East. Medicinal herbs are the most dominant ethnopharmacological formula used among cancer's patients in the Near East. The data obtained highlight for the first time the most commonly used medicinal plants in the Near East area for cancer treatment illustrating their importance as natural anticancer agents. The literature survey reveals that various Arum species, various Artemisia species, Calotropis procera, Citrullus colocynthis, Nigella sativa, Pulicaria crispa, various Urtica species, Withania somnifera, and others belong to the most frequently used plants among cancer patients in the Near East countries. Molecular modes of action that have been investigated for plant extracts and isolated compounds from Near East include cell cycle arrest and apoptosis induction with participation of major player in these processes such as p53 and p21, Bcl-2, Bax, cytochrome c release, poly (ADP-ribose) polymerase cleavage, activation of caspases, etc. Conclusion: The ethnopharmacology of the Near East was influenced by Arabic and Islamic medicine and might be promising for developing new natural and safe anticancer agents. Further research is required to elucidate their cellular and molecular mechanisms and to estimate their clinical activity.

Role of ginsenosides in reactive oxygen species-mediated anticancer therapy

Cancer is still a global public health problem, which is the leading cause of death in most countries. Ginseng has been used for centuries all over the world as a panacea that promotes longevity. As the king of herb plants, ginseng holds great promise as a new treatment option which is used either by itself or in combination with other medicinal ingredients that is widely accepted as complementary and alternative medicine in cancer therapy. Ginsenosides, the major pharmacologically active ingredients of ginseng, have been shown to have multiple medicinal effects including prominent anticancer activity. The purpose of this review is to give our perspective about the roles of ginsenosides in reactive oxygen species (ROS)-mediated anticancer therapy. Additionally, to provide new sheds light for further improvement and carry out pre-clinical and clinical trials to develop it successfully into a potential anticancer agent. Panax herbs and their derivate/metabolites ginsenosides exert beneficial effects for treating various types of cancers. The mechanism of ROS-mediated anticancer activities of ginsenosides varies depending on the specific type of cancer cells involved. Ginsenosides may suppress cancer cell proliferation through anti-oxidation on tumor initiation and induce apoptosis, paraptosis or autophagy via generation of ROS on tumor progression, promotion, angiogenesis, invasion and metastasis by various signaling pathways e.g., activation of AMPK, MEK, ASK-1/JNK, ESR2-NCF1-ROS, ER-dependent PI3K/Akt/Nrf2, P53-CHOP, ROS-JNK-autophagy, and/or inhibition of PI3K/Akt signaling pathways. These multiple effects rather than a single may play a crucial role in emerging ginsenosides as a successful anticancer drug.

Therapeutic potential of gambogic acid, a caged xanthone, to target cancer

Natural compounds have enormous biological and clinical activity against dreadful diseases such as cancer, as well as cardiovascular and neurodegenerative disorders. In spite of the widespread research carried out in the field of cancer therapeutics, cancer is one of the most prevalent diseases with no perfect treatment till date. Adverse side effects and the development of chemoresistance are the imperative limiting factors associated with conventional chemotherapeutics. For this reason, there is an urgent need to find compounds that are highly safe and efficacious for the prevention and treatment of cancer. Gambogic acid (GA) is a xanthone structure extracted from the dry, brownish gamboge resin secreted from the Garcinia hanburyi tree in Southeast Asia and has inherent anti-cancer properties. In this review, the molecular mechanisms underlying the targets of GA that are liable for its effective anti-cancer activity are discussed that reveal the potential of GA as a pertinent candidate that can be appropriately developed and designed into a capable anti-cancer drug.

Oridonin, a novel lysine acetyltransferases inhibitor, inhibits proliferation and induces apoptosis in gastric cancer cells through p53- and caspase-3-mediated mechanisms

Lysine acetylation has been reported to involve in the pathogenesis of multiple diseases including cancer. In our screening study to identify natural compounds with lysine acetyltransferase inhibitor (KATi) activity, oridonin was found to possess acetyltransferase-inhibitory effects on multiple acetyltransferases including P300, GCN5, Tip60, and pCAF. In gastric cancer cells, oridonin treatment inhibited cell proliferation in a concentration-dependent manner and down-regulated the expression of p53 downstream genes, whereas p53 inhibition by PFT-α reversed the antiproliferative effects of oridonin. Moreover, oridonin treatment induced cell apoptosis, increased the levels of activated caspase-3 and caspase-9, and decreased the mitochondrial membrane potential in gastric cancer cells in a concentration-dependent manner. Caspase-3 inhibition by Ac-DEVD-CHO reversed the proapoptosis effect of oridonin. In conclusion, our study identified oridonin as a novel KATi and demonstrated its tumor suppressive effects in gastric cancer cells at least partially through p53-and caspase-3-mediated mechanisms.

Chrysin attenuates progression of ovarian cancer cells by regulating signaling cascades and mitochondrial dysfunction

Chrysin is mainly found in passion flowers, honey, and propolis acts as a potential therapeutic and preventive agent to inhibit proliferation and invasion of various human cancer cells. Although chrysin has anti-carcinogenic effects in several cancers, little is known about its functional roles in ovarian cancer which shows poor prognosis and chemoresistance to traditional therapeutic agents. In the present study, we investigated functional roles of chrysin in progression of ovarian cancer cells using ES2 and OV90 (clear cell and serous carcinoma, respectively) cell lines. Results of the current study demonstrated that chrysin inhibited ovarian cancer cell proliferation and induced cell death by increasing reactive oxygen species (ROS) production and cytoplasmic Ca²⁺ levels as well as inducing loss of mitochondrial membrane potential (MMP). Moreover, chrysin activated mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K)/AKT pathways in ES2 and OV90 cells in concentration-response experiments. Collectively, our results led us to propose that chrysin-induced apoptotic events are mediated by the activation of PI3K and MAPK pathways in human ovarian cancer cells.

The mechanistic antitumor study of myricanol 5-fluorobenzyloxy ether in human leukemic cell HL-60

AIM

The aim of the study was to explore the growth inhibitory effect of myricanol 5-fluorobenzyloxy ether (5FEM) and the underlying mechanism in human leukemic cells HL-60.

MATERIALS & METHODS

5FEM was obtained by chemical modification of myricanol with fluorobenzyloxy ether at the OH(5) position. The cytotoxicity, cell apoptosis, cell cycle and the expression of key apoptosis-related genes in HL-60 were evaluated.

RESULTS & CONCLUSION

5FEM can significantly inhibited growth of HL-60 cells, increased the G2/M population and upregulated the expression of Bax, Fas, FasL, caspase-9 and p21 and downregulated that of Bcl-2 and survivin. The results enhance our understanding of 5FEM and aid the discovery of novel myricanol derivatives as potential antitumor agents.

Cytotoxic and chemosensitization effects of Scutellarin from traditional Chinese herb Scutellaria altissima L. in human prostate cancer cells

Scutellaria altissima L. is a common traditional Chinese medicine used to treat inflammation in some countries. Scutellarin, an active major flavone glycoside isolated from the traditional Chinese medicine Scutellaria altissima L., has been shown to offer various beneficial biochemical effects on cerebrovascular diseases and inflammation. However, the antiproliferative effects of Scutellarin in prostate cancer and the underlying mechanism are not fully elucidated. In the present study, we aimed to ascertain whether Scutellarin inhibits cancer cell growth and to further explore the molecular mechanism. Scutellarin enhanced the sensitivity of prostate cancer cells to cisplatin. MTT assays revealed that cell viability was significantly decreased in the prostate cancer cells treated with Scutellarin. Flow cytometric analysis indicated that Scutellarin suppressed cell proliferation by promoting G2/M arrest and inducing apoptosis. We employed western blotting to delineate the underlying mechanisms involved in the G2/M arrest and apoptosis. Comet assay and γH2AX immunocytochemistry were used to detect levels of DNA damage in PC3 cells exposed to Scutellarin and/or cisplatin. Our data revealed that Scutellarin significantly induced prostate cancer cell apoptosis by activating the caspase cascade. An increase in the Bax/Bcl-2 ratio, depolarization of mitochondrial membrane potential and cell cycle arrest at G2/M phase were accompanied by the apoptosis induction. Additionally, Scutellarin altered the protein expression of cell cycle and apoptosis regulatory genes by downregulating Cdc2, cyclin B1 and Bcl-2 and upregulating caspase-3, caspase-9 and Bax in prostate cancer cells. Furthermore, Scutellarin sensitized PC3 cells to cisplastin treatment in a dose-dependent manner. Taken together, our data confirmed the cytotoxicity of Scutellarin against prostate cancer PC3 cells and provide new findings in regards to Scutellarin sensitizing prostate cancer cells to chemotherapy. Our findings suggest that Scutellarin has potential to be used as a novel antineoplastic therapeutic candidate for prostate cancer patients.

Indole-3-carbinol induces apoptosis of chronic myelogenous leukemia cells through suppression of STAT5 and Akt signaling pathways

Signal transducer and activator of transcription 5 and Akt pathways, implicated in signaling transduction downstream of BCR-ABL, play critical roles in the pathogenesis of chronic myeloid leukemia. Therefore, idenication of novel compounds that modulate the activity of such pathways could be a new approach in the treatment of chronic myeloid leukemia. Previous studies have demonstrated that indole-3-carbinol inhibits the proliferation and induces apoptosis of various tumor cells. However, its anticancer activity against chronic myeloid leukemia cells and the underlying mechanism remain unclear. Our data revealed that indole-3-carbinol promoted mitochondrial apoptosis of chronic myeloid leukemia-derived K562 cells, as evidenced by the activation of caspases and poly (ADP-ribose) polymerase cleavage. Treatment with indole-3-carbinol was found to be associated with a decrease in the cellular levels of phospho-Akt and phospho-signal transducer and activator of transcription 5. In addition, real-time polymerase chain reaction analysis showed that the downregulation of genes is regulated by Akt and signal transducer and activator of transcription 5. We also found that treatment with indole-3-carbinol resulted in the activation of the p38 mitogen-activated protein kinase and reduced expression of human telomerase and c-Myc. Collectively, these results demonstrate that the oncogenic signal transducer and activator of transcription 5/Akt pathway is a cellular target for indole-3-carbinol in chronic myeloid leukemia cells. Thus, this clinically tested natural compound can be a potential candidate in the treatment of chronic myeloid leukemia following confirmation with clinical studies.

Induction of G 2 /M arrest and apoptosis through mitochondria pathway by a dimer sesquiterpene lactone from Smallanthus sonchifolius in HeLa cells

Dimer sesquiterpene lactones (SLs), uvedafolin and enhydrofolin, against four monomer SLs isolated from yacon, Smallanthus sonchifolius, leaf were the most cytotoxic substances on HeLa cells (IC₅₀ values 2.96–3.17 μM at 24 hours). However, the cytotoxic mechanism of dimer SL has not been elucidated yet. Therefore, in this study, we clarified the in vitro cytotoxic mechanism of uvedafolin on the HeLa cells, and evaluated the cytotoxicity against NIH/3T3 cells which were used as normal cells. In consequence, the dimer SLs had low toxicity for the NIH/3T3 cells (IC₅₀ 4.81–4.98 μM at 24 hours) and then the uvedafolin mediated cell cycle arrest at the G₂/M phase and induced apoptosis on the HeLa cells evidenced by appearance of a subG1 peak. Uvedafolin induced apoptosis was attributed to caspase-9 and caspase-3/7 activities. An effectively induced apoptosis pathway was demonstrated from mitochondria membrane potential change and cytochrome c release to cytosol. These results reveal that uvedafolin induced apoptosis via the mitochondria pathway. The present results indicate the potential of uvedafolin as a leading compound of new anticancer agents.

Deoxyelephantopin and Isodeoxyelephantopin as Potential Anticancer Agents with Effects on Multiple Signaling Pathways

Cancer is the 2nd leading cause of death worldwide. The development of drugs to target only one specific signaling pathway has limited therapeutic success. Developing chemotherapeutics to target multiple signaling pathways has emerged as a new prototype for cancer treatment. Deoxyelephantopin (DET) and isodeoxyelephantopin (IDET) are sesquiterpene lactone components of “Elephantopus scaber and Elephantopus carolinianus”, traditional Chinese medicinal herbs that have long been used as folk medicines to treat liver diseases, diabetes, diuresis, bronchitis, fever, diarrhea, dysentery, cancer, and inflammation. Recently, the anticancer activity of DET and IDET has been widely investigated. Here, our aim is to review the current status of DET and IDET, and discuss their anticancer activity with specific emphasis on molecular targets and mechanisms used by these compounds to trigger apoptosis pathways which may help to further design and conduct research to develop them as lead therapeutic drugs for cancer treatments. The literature has shown that DET and IDET induce apoptosis through multiple signaling pathways which are deregulated in cancer cells and suggested that by targeting multiple pathways simultaneously, these compounds could selectively kill cancer cells. This review suggests that DET and IDET hold promising anticancer activity but additional studies and clinical trials are needed to validate and understand their therapeutic effect to develop them into potent therapeutics for the treatment of cancer.

Beta sitosterol and Daucosterol (phytosterols identified in Grewia tiliaefolia) perturbs cell cycle and induces apoptotic cell death in A549 cells

Lung cancer is the leading cause of cancer related deaths both in developed and developing countries. Since majority of the existing therapeutic methods harms both normal and malignant cells, a viable alternative is to switch into safe and beneficial traditional medicinal plants. Hence the present study was framed to identify selective anti-lung cancer agents from the medicinal plant Grewia tiliaefolia (GT). Cell viability experiments showed that benzene extract of GT (BGT) leaf effectively inhibited the growth of A549 cells, while being non-toxic to normal human lung L132 and PBMC cells. Ames and comet assays demonstrated that BGT is of non-mutagenic and non-genotoxic nature in untransformed cells. The hematological and histopathological profiles of the in vivo acute and sub-acute toxicity studies demonstrated that BGT is safe and tolerable. Importantly, western blot analysis and Annexin V-FITC staining confirmed that BGT promotes mitochondrial dependent apoptotic cell death in A549 cells by arresting cell cycle at G2/M phase. Bio-assay guided fractionation revealed the presence of phytosteols (β-sitosterol and daucosterol) which significantly inhibited the growth of A549 cells both alone and in combination. This study warrants that these phytosterols in alone or in combination can be considered as safe and potential drug candidates for lung cancer treatment.

Vitamin K and its analogs: Potential avenues for prostate cancer management

Epidemiological studies have demonstrated a relationship between cancer incidence and dietary habits. Especially intake of certain essential nutrients like vitamins has been shown to be beneficial in experimental studies and some clinical trials. Vitamin K (VK) is an essential nutrient involved in the blood clotting cascade, and there are considerable experimental data demonstrating its potential anticancer activity in several cancer types including prostate cancer. Previous in vitro and in vivo studies have focused mainly on anti-oxidative effects as the underlying anticancer mechanism of VK. However, recent studies reveal that VK inhibits the growth of cancer cells through other mechanisms, including apoptosis, cell cycle arrest, autophagy, and modulation of various transcription factors such as Myc and Fos. In the present review, we focus on the anticancer effect of dietary VK and its analogs on prostate cancer, with an emphasis on the signaling pathways that are activated following exposure to these compounds. This review also highlights the potential of VK and its derivatives as an adjuvant treatment in combination with other vitamins or with chemotherapeutic drugs. Based on our recent results and a review of the existing literature, we present evidence that VK and its derivatives can potentially be explored as cancer therapy, especially for prostate cancer.

Survival rates of homozygotic Tp53 knockout rats as a tool for preclinical assessment of cancer prevention and treatment

Background

The gene that encodes tumor protein p53, Tp53, is mutated or silenced in most human cancers and is recognized as one of the most important cancer drivers. Homozygotic Tp53 knockout mice, which develop lethal cancers early in their lives, are already used in cancer prevention studies, and now Tp53 knockout rats have also been generated. This study assessed feasibility of using homozygous Tp53 knockout rats to evaluate the possible outcome of cancer chemoprevention.

Methods

A small colony of Tp53 knockout rats with a Wistar strain genetic background was initiated and maintained in the animal house at our institution. Tp53 heterozygotic females were bred with Tp53 homozygous knockout males to obtain a surplus of knockout homozygotes. To evaluate the reproducibility of their lifespan, 4 groups of Tp53 homozygous knockout male rats born during consecutive quarters of the year were kept behind a sanitary barrier in a controlled environment until they reached a moribund state. Their individual lifespan data were used to construct quarterly survival curves.

Results

The four consecutive quarterly survival curves were highly reproducible. They were combined into a single “master” curve for use as a reference in intervention studies. The average lifespan of untreated male Tp53 homozygous knockout rats was normally distributed, with a median of 133 days. Sample size vs. effect calculations revealed that confirming a 20% and 30% increase in the lifespan would respectively require a sample size of 18 and 9 animals (when assessed using the t-test with a power of 80% and alpha set at 0.05). As an example, the Tp53 homozygous knockout rat model was used to test the chemopreventive properties of carnosine, a dipeptide with suspected anticancer properties possibly involving modulation of the mTOR pathway. The result was negative.

Conclusion

Further evaluation of the Tp53 homozygous knockout male rat colony is required before it can be confirmed as a viable tool for assessing new methods of cancer prevention or treatment.

Down-Regulation of MicroRNA-210 Confers Sensitivity towards 1'S-1'-Acetoxychavicol Acetate (ACA) in Cervical Cancer Cells by Targeting SMAD4

MicroRNAs (miRNAs) are short non-coding RNAs that regulate genes posttranscriptionally. Past studies have reported that miR-210 is up-regulated in many cancers including cervical cancer, and plays a pleiotropic role in carcinogenesis. However, its role in regulating response towards anti-cancer agents has not been fully elucidated. We have previously reported that the natural compound 1'S-1'-acetoxychavicol acetate (ACA) is able to induce cytotoxicity in various cancer cells including cervical cancer cells. Hence, this study aims to investigate the mechanistic role of miR-210 in regulating response towards ACA in cervical cancer cells. In the present study, we found that ACA down-regulated miR-210 expression in cervical cancer cells, and suppression of miR-210 expression enhanced sensitivity towards ACA by inhibiting cell proliferation and promoting apoptosis. Western blot analysis showed increased expression of mothers against decapentaplegic homolog 4 (SMAD4), which was predicted as a target of miR-210 by target prediction programs, following treatment with ACA. Luciferase reporter assay confirmed that miR-210 binds to sequences in 3'UTR of SMAD4. Furthermore, decreased in SMAD4 protein expression was observed when miR-210 was overexpressed. Conversely, SMAD4 protein expression increased when miR-210 expression was suppressed. Lastly, we demonstrated that overexpression of SMAD4 augmented the anti-proliferative and apoptosis-inducing effects of ACA. Taken together, our results demonstrated that down-regulation of miR-210 conferred sensitivity towards ACA in cervical cancer cells by targeting SMAD4. These findings suggest that combination of miRNAs and natural compounds could provide new strategies in treating cervical cancer.

Suppression of microRNA-629 enhances sensitivity of cervical cancer cells to 1'S-1'-acetoxychavicol acetate via regulating RSU1

Background

Cervical cancer is the fourth most frequent malignancy affecting women worldwide, but drug resistance and toxicities remain a major challenge in chemotherapy. The use of natural compounds is promising because they are less toxic and able to target multiple signaling pathways. The 1′S-1′-acetoxychavicol acetate (ACA), a natural compound isolated from wild ginger Alpinia conchigera, induced cytotoxicity on various cancer cells including cervical cancer. MicroRNAs (miRNAs) are short noncoding RNAs that regulate numerous biological processes, such as apoptosis and chemosensitivity. Past studies reported that miR-629 is upregulated in many cancers, and its expression was altered in ACA-treated cervical cancer cells. However, the role of miR-629 in regulating sensitivity toward ACA or other anticancer agents has not been reported. Hence, this study aims to investigate the role of miR-629 in regulating response toward ACA on cervical cancer cells.

Methods

The miR-629 expression following transfection with miR-629 hairpin inhibitor and hairpin inhibitor negative control was measured using quantitative real-time polymerase chain reaction (RT-qPCR). The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to investigate sensitivity toward ACA. Apoptosis was detected using Annexin V/propidium iodide and Caspase 3/7 assays. The gene target for miR-629 was identified using miRNA target prediction programs, luciferase reporter assay and Western blots. Gene overexpression studies were performed to evaluate its role in regulating response toward ACA.

Results

Transfection with miR-629 hairpin inhibitor downregulated its expression in both cervical cancer cell lines. Suppression of miR-629 increased sensitivity toward ACA by reducing cell proliferation and inducing apoptosis. Luciferase reporter assay confirmed RSU1 as a direct target of miR-629. Overexpression of miR-629 decreased RSU1 protein expression, while inhibition of miR-629 increased RSU1 protein expression. Overexpression of RSU1 augmented antiproliferative and apoptosis-inducing effects of ACA.

Conclusion

Our findings showed that combination of ACA with miR-629 and RSU1 may provide a potential strategy in treating cervical cancer.

Understanding the Effectiveness of Natural Compound Mixtures in Cancer through Their Molecular Mode of Action

Many approaches to cancer management are often ineffective due to adverse reactions, drug resistance, or inadequate target specificity of single anti-cancer agents. In contrast, a combinatorial approach with the application of two or more anti-cancer agents at their respective effective dosages can achieve a synergistic effect that boosts cytotoxicity to cancer cells. In cancer, aberrant apoptotic pathways allow cells that should be killed to survive with genetic abnormalities, leading to cancer progression. Mutations in apoptotic mechanism arising during the treatment of cancer through cancer progression can consequently lead to chemoresistance. Natural compound mixtures that are believed to have multiple specific targets with minimal acceptable side-effects are now of interest to many researchers due to their cytotoxic and chemosensitizing activities. Synergistic interactions within a drug mixture enhance the search for potential molecular targets in cancer cells. Nonetheless, biased/flawed scientific evidence from natural products can suggest false positive therapeutic benefits during drug screening. In this review, we have taken these factors into consideration when discussing the evidence for these compounds and their synergistic therapeutic benefits in cancer. While there is limited evidence for clinical efficacy for these mixtures, in vitro data suggest that these preparations merit further investigation, both in vitro and in vivo.

Emerging Cytotoxic Alkaloids in the Battle against Cancer: Overview of Molecular Mechanisms

Considered as the second deadliest disease globally, cancer has captured the attention of researchers who have been trying with perseverance to decode its hidden aspects, to find new prognosis methods, and to develop better and more effective treatments. Plants have continuously offered an excess of unique secondary metabolites with remarkable biological applications. Alkaloids, one of the most abundant metabolites, constitute a large conglomerate of basic heterocyclic nitrogen-containing natural compounds which are normally produced by plants as toxic substances. Out of the 27,000 different alkaloids, more than 17,000 have displayed diversified pharmacological properties including anticancer activities. These metabolites have been classified either according to their chemical structures or their taxonomic origin. None of the researched alkaloids have been classified according to their molecular mechanism of action against cancer. In fact, only a fraction of the tremendous number of anticancer alkaloids has been copiously mentioned in journals. Here, we aim to provide a summary of the literature on some of the promising anticancer alkaloids that have not been well discussed previously and to classify them according to their molecular mechanisms of action. This review will provide a better understanding of the anticancer mechanisms of these promising natural products that are a rich reservoir for drug discovery.

Isomahanine induces endoplasmic reticulum stress and simultaneously triggers p38 MAPK-mediated apoptosis and autophagy in multidrug-resistant human oral squamous cell carcinoma cells

Advanced oral squamous cell carcinoma (OSCC) is typically aggressive and closely correlated with disease recurrence and poor survival. Multidrug resistance (MDR) is the most critical problem leading to therapeutic failure. Investigation of novel anticancer candidates targeting multidrug-resistant OSCC cells may provide a basis for developing effective strategies for OSCC treatment. In the present study, we investigated the cytotoxic mechanism of a carbazole alkaloid, namely isomahanine, in a multidrug‑resistant OSCC cell line CLS-354/DX. We demonstrated that CLS-354/DX cells overexpressing multidrug resistance-associated protein 1 (MRP1) were resistant to anticancer drugs cisplatin and camptothecin. Isomahanine effectively induced cytotoxicity against CLS-354/DX cells regardless of resistance. Apoptosis as determined by FITC‑Annexin V/PI staining and western blot analysis of cleaved caspase-3 and cleaved poly(ADP‑ribose) polymerase (PARP) was significantly induced in a time-dependent manner upon isomahanine treatment. Isomahanine-induced caspase‑dependent apoptosis was determined using z-VAD‑fmk. The effects on autophagy in isomahanine-treated cells were investigated via conversion of LC3B and degradation of p62/SQSTM1 (p62). Isomahanine obviously induced autophagic flux as shown by an increase in punctate GFP-LC3B and the LC3B-II/LC3B-I ratio with a concomitant decrease in p62 levels. Autophagy inhibitors 3-methyladenine (3-MA) and chloroquine (CQ) protected isomahanine-induced cell death, indicating the activation of autophagic cell death. Endoplasmic reticulum (ER) stress and MAPK activation were examined to elucidate the mechanism underlying cell death. The expression levels of PERK, CHOP and phosphorylated MAPK (p38, ERK1/2 and JNK1/2) were upregulated following isomahanine treatment. We found that p38 MAPK inhibitor (SB203580) significantly attenuated isomahanine-induced apoptosis and autophagic flux and this prevented cell death. Collectively, the present study demonstrated that isomahanine was able to induce ER stress and trigger p38 MAPK-mediated apoptosis and autophagic cell death in multidrug-resistant OSCC cells. The potential cytotoxic action of isomahanine may provide the development of anticancer candidates for treating multidrug-resistant cancer.