Targeting the cell cycle for cancer therapy

Innovating Cancer Treatment Through Cell Cycle, Telomerase, Angiogenesis, and Metastasis

Cancer remains a formidable challenge in the field of medicine, necessitating innovative therapeutic strategies to combat its relentless progression. The cell cycle, a tightly regulated process governing cell growth and division, plays a pivotal role in cancer development. Dysregulation of the cell cycle allows cancer cells to proliferate uncontrollably. Therapeutic interventions designed to disrupt the cell cycle offer promise in restraining tumor growth and progression. Telomerase, an enzyme responsible for maintaining telomere length, is often overactive in cancer cells, conferring them with immortality. Targeting telomerase presents an opportunity to limit the replicative potential of cancer cells and hinder tumor growth. Angiogenesis, the formation of new blood vessels, is essential for tumor growth and metastasis. Strategies aimed at inhibiting angiogenesis seek to deprive tumors of their vital blood supply, thereby impeding their progression. Metastasis, the spread of cancer cells from the primary tumor to distant sites, is a major challenge in cancer therapy. Research efforts are focused on understanding the underlying mechanisms of metastasis and developing interventions to disrupt this deadly process. This review provides a glimpse into the multifaceted approach to cancer therapy, addressing critical aspects of cancer biology-cell cycle regulation, telomerase activity, angiogenesis, and metastasis. Through ongoing research and innovative strategies, the field of oncology continues to advance, offering new hope for improved treatment outcomes and enhanced quality of life for cancer patients.

Green nanotech paradigm for enhancing sesquiterpene lactone therapeutics in cancer

In the field of cancer therapy, sesquiterpene lactones (SLs) derived from diverse Dicoma species demonstrate noteworthy bioactivity. However, the translation of their full therapeutic potential into clinical applications encounters significant challenges, primarily related to solubility, bioavailability, and precise drug targeting. Despite these obstacles, our comprehensive review introduces an innovative paradigm shift that integrates the inherent therapeutic properties of SLs with the principles of green nanotechnology. To overcome issues of solubility, bioavailability, and targeted drug delivery, eco-friendly strategies are proposed for synthesizing nanocarriers. Green nanotechnology has emerged as a focal point in addressing environmental and health concerns linked to conventional treatments. This progressive approach of green nanotechnology holds promise for the development of safe and sustainable nanomaterials, particularly in the field of drug delivery. This groundbreaking methodology signifies a pioneering advancement in the creation of novel and effective anticancer therapeutics. It holds substantial potential for transforming cancer treatment and advancing the landscape of natural product research.

Synthesis of Quinoline-2-Carboxylic Acid Aryl Ester and Its Apoptotic Action on PC3 Prostate Cancer Cell Line

The aim of the present study is to synthesise an aryl ester compound from quinoline-2-carboxylic acid to evaluate its apoptotic, cell cycle blockade, and antiproliferative activity on the prostate cancer cell lines (PC3). Chromatographic and spectroscopic analysis was used to identify the synthesised carboxylic acid compound. The synthesised compound was treated with a PC3 cell line for 24 h with control. The cells were treated at various concentration ranges of 0, 3.91, 7.81, 15.63, 31.25, 62.5, 125, 250, 500, and 1000 µg/mL each. The cytotoxicity effect was studied by MTT assay, and their anticancer activity was further evaluated using cell cycle analysis, DNA fragmentation assay, acridine orange-ethidium bromide staining, and Western blot analysis. The end antiproliferative result showed that PC3 cell viability decreases in a concentration-dependent manner and the synthesised compound exhibited potent cytotoxicity against PC3 cells with an IC50 value of 26 µg/mL at the concentration of 125 µg. The increase in the number of apoptotic cells was observed after treating PC3 cells with the sample in double-staining methods. S phase of the cell cycle was significantly blocked by the test sample, and a typical ladder pattern of internucleosomal fragmentation was observed. A decrease in the live cells was observed with the sample in AO/ET-BR. A significant increase in the Bax expression and a decrease in Bcl-2 expression observed enhance the activity of caspases-7 and -9. The synthesised compound had shown to possess excellent cytotoxic effect through inducing apoptosis, especially causing cell cycle arrest at the S phase.

Inflammatory Cells Can Alter the Levels of H3K9ac and γH2AX in Dysplastic Cells and Favor Tumor Phenotype

Oral potentially malignant disorders (OPMD) are clinical presentations that carry an increased risk of cancer development. Currently, epithelial dysplasia grade is based on architectural and cytological epithelial changes and is used to predict the malignant transformation of these lesions. However, predicting which OPMD will progress to a malignant tumor is very challenging. Inflammatory infiltrates can favor cancer development, and recent studies suggest that this association with OPMD lesions may be related to the etiology and/or aggressive clinical behavior of these lesions. Epigenetic changes such as histone modifications may mediate chronic inflammation and also favor tumor cells in immune resistance and evasion. This study aimed to evaluate the relationship between histone acetylation (H3K9ac) and DNA damage in the context of dysplastic lesions with prominent chronic inflammation. Immunofluorescence of "low-risk" and "high-risk" OPMD lesions (n = 24) and inflammatory fibrous hyperplasia (n = 10) as the control group was performed to assess histone acetylation levels and DNA damage through the phosphorylation of H2AX (γH2AX). Cell co-culture assays with PBMCs and oral keratinocyte cell lines (NOK-SI, DOK, and SCC-25) were performed to assess proliferation, adhesion, migration, and epithelial-mesenchymal transition (EMT). Oral dysplastic lesions showed a hypoacetylation of H3K9 and low levels of γH2AX compared to control. The contact of dysplastic oral keratinocytes with PBMCs favored EMT and the loss of cell-cell adhesion. On the other hand, p27 levels increased and cyclin E decreased in DOK, indicating cell cycle arrest. We conclude that the presence of chronic inflammation associated to dysplastic lesions is capable of promoting epigenetic alterations, which in turn can favor the process of malignant transformation.

Medicinal chemistry perspective of pyrido[2,3-d]pyrimidines as anticancer agents

Cancer is a major cause of deaths across the globe due to chemoresistance and lack of selective chemotherapy. Pyrido[2,3-d]pyrimidine is an emerging scaffold in medicinal chemistry having a broad spectrum of activities, including antitumor, antibacterial, CNS depressive, anticonvulsant, and antipyretic activities. In this study, we have covered different cancer targets, including tyrosine kinase, extracellular regulated protein kinases - ABL kinase, phosphatidylinositol-3 kinase, mammalian target of rapamycin, p38 mitogen-activated protein kinases, BCR-ABL, dihydrofolate reductase, cyclin-dependent kinase, phosphodiesterase, KRAS and fibroblast growth factor receptors, their signaling pathways, mechanism of action and structure-activity relationship of pyrido[2,3-d]pyrimidine derivatives as inhibitors of the above-mentioned targets. This review will represent the complete medicinal and pharmacological profile of pyrido[2,3-d]pyrimidines as anticancer agents, and will help scientists to design new selective, effective and safe anticancer agents.

The Role of CDK Pathway Dysregulation and Its Therapeutic Potential in Soft Tissue Sarcoma

Soft tissue sarcomas (STSs) are tumors that are challenging to treat due to their pathologic and molecular heterogeneity and their tumor biology that is not yet fully understood. Recent research indicates that dysregulation of cyclin-dependent kinase (CDK) signaling pathways can be a strong driver of sarcogenesis. CDKs are enzyme forms that play a crucial role in cell-cycle control and transcription. They belong to the protein kinases group and to the serine/threonine kinases subgroup. Recently identified CDK/cyclin complexes and established CDK/cyclin complexes that regulate the cell cycle are involved in the regulation of gene expression through phosphorylation of critical components of transcription and pre-mRNA processing mechanisms. The current and continually growing body of data shows that CDKs play a decisive role in tumor development and are involved in the proliferation and growth of sarcoma cells. Since the abnormal expression or activation of large numbers of CDKs is considered to be characteristic of cancer development and progression, dysregulation of the CDK signaling pathways occurs in many subtypes of STSs. This review discusses how reversal and regulation can be achieved with new therapeutics and summarizes the current evidence from studies regarding CDK modulation for STS treatment.

Cedrus atlantica extract exerts antiproliferative effect on colorectal cancer through the induction of cell cycle arrest and apoptosis

Cedrus atlantica is a tree species found in Morocco with many clinical benefits in genitourinary, musculoskeletal, and skin systems. Previous studies have reported that extracts of Cedrus atlantica have antioxidant, antimicrobial, and anticancer properties. However, its role in colorectal cancer (CRC) remains unclear. The present study investigated the effects and underlying mechanisms of Cedrus atlantica extract (CAt) using HT-29 (human colorectal adenocarcinoma) and CT-26 CRC cell lines. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed to measure cell viability. Flow cytometry analysis and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay were used to study the cell cycle and cell apoptosis, respectively. The expression of cell cycle and apoptosis-associated proteins was detected by western blotting or immunohistochemical (IHC) staining. CAt showed significant inhibitory effects on the proliferation of HT-29 and CT-26 cells, and combined with the clinical drug, 5-fluorouracil (5-FU), exhibited synergistic effects. CAt induced cell cycle arrest at the G0/G1 phase through the upregulation of p53/p21 and the downregulation of cyclin-dependent kinases (CDKs)/cyclins. In addition, CAt-treated cells exhibited chromatin condensation, DNA fragmentation, and apoptotic bodies, which are typical characteristics of apoptosis activated via both the extrinsic (Fas ligand (FasL)/Fas/caspase-8) and intrinsic (Bax/caspase-9) pathways. Importantly, CAt suppressed tumor progression and prolonged the life span of mice within a well-tolerated dose. Therefore, our findings provide novel insights into the use of CAt for the treatment of CRC.

Evaluation of anti-cancer potential of Excoecaria agallocha (L.) leaf extract on human cervical cancer (SiHa) cell line and assessing the underlying mechanism of action

Background

The incidence of cervical cancer is increasing at an alarming rate in many countries and presently, it is the most common form of malignant cancer being reported among women in India. Development of novel approach for cervical cancer therapy, sparing healthy normal cells overcoming the limitations of prevailing therapies is of prime importance. Mangroves constitute a significant repository of medicinally important plants. Thus, in this study, we aimed to determine the anticancer activity of the mangrove Excoecaria agallocha L. leaf extracts on human cervical cancer (SiHa HPV 16+) cell line with subsequent characterization of the bioactive compounds conferring the anticancer activity and studying the probable underlying mechanism of action of the purified plant extract.

Results

The plant extract was subjected to silica gel column chromatography and the fractions obtained were analyzed for cytotoxic activity against SiHa cells by MTT assay. One out of the three eluted fractions exhibited selective toxicity against SiHa cells with an IC50 value of 15.538 ± 0.577 µg/mL, while it had no cytotoxic effect on normal healthy human peripheral blood mononuclear cells. High-resolution liquid chromatography mass spectroscopy, coupled to electron spray ionization and diode array detection analysis, led to the structure elucidation and identification of a few pharmacologically important compounds, with Bergenin being present in the highest abundance. Fluorescence microscopy results revealed that the plant extract fraction induced LC3 puncta formation, in EGFP- SiHa cells indicating the onset of autophagy, with simultaneous stimulation of mitophagy. The plant extract also inhibited proliferation of the SiHa-smac-mCherry cells by second mitochondria-derived activator of caspase (SMAC)—induced cytochrome c dependent apoptosis, that was further confirmed with Caspase-3 activation by colorimetric assay. The GFP-dgn in SiHa cells was remarkably protected from proteasomal degradation that might upregulate the survivability of the cells significantly. Flow cytometry followed by Western blot analysis further asserted the ability of the plant extract fraction to cause cell cycle arrest of SiHa cells in the G2/M phase by significantly reducing protein expression levels of cyclin B1 and D1, decreasing Cdc2 level and simultaneously increasing p21 and p53 levels.

Conclusion

It could be inferred that the aqueous extract of E. agallocha successfully decreased the proliferation of SiHa cervical cancer cells through induction of autophagy and apoptosis in a concerted manner, with simultaneous stimulation of mitophagy and G2/M phase cell cycle arrest, hinting at Bergenin being the major compound conferring the anti-cancer activity of the plant extract. Thus, isolation of the identified bioactive compounds from E. agallocha and their subsequent purification for drug development might serve as a novel medicinal approach for the treatment of cervical cancer in conjugation with existing therapeutic methods.

Vanadium-Flavonoid Complexes: A Promising Class of Molecules for Therapeutic Applications

Several reports have revealed the superior biological activity of metal ion-flavonoid complexes when compared with the parent flavonoid. Among the different metal ions explored, vanadium and its compounds are in the forefront because of their anticancer and antidiabetic properties. However, the toxicity of vanadium-based ions and their inorganic derivatives limits their therapeutic applications. Complexation of vanadium with flavonoids not only reduces its adverse effects but also augments its biological activity. This Review discusses the nature of coordination in vanadium-flavonoid complexes, their structure-activity correlations, with special emphasis on their therapeutic activities. Several investigations suggest that the superior biological activity of vanadium complexes arise because of their ability to regulate metabolic pathways distinct from those acted upon by vanadium alone. These studies serve to decipher the underlying molecular mechanism of vanadium-flavonoid complexes that can be explored further for generating a series of novel compounds with improved pharmacological and therapeutic performance.

An Integrative Systems Biology Approach Identifies Molecular Signatures Associated with Gallbladder Cancer Pathogenesis

Gallbladder cancer (GBC) has a lower incidence rate among the population relative to other cancer types but is a major contributor to the total number of biliary tract system cancer cases. GBC is distinguished from other malignancies by its high mortality, marked geographical variation and poor prognosis. To date no systemic targeted therapy is available for GBC. The main objective of this study is to determine the molecular signatures correlated with GBC development using integrative systems level approaches. We performed analysis of publicly available transcriptomic data to identify differentially regulated genes and pathways. Differential co-expression network analysis and transcriptional regulatory network analysis was performed to identify hub genes and hub transcription factors (TFs) associated with GBC pathogenesis and progression. Subsequently, we assessed the epithelial-mesenchymal transition (EMT) status of the hub genes using a combination of three scoring methods. The identified hub genes including, CDC6, MAPK15, CCNB2, BIRC7, L3MBTL1 were found to be regulators of cell cycle components which suggested their potential role in GBC pathogenesis and progression.

Application of nanoparticles in cancer therapy with an emphasis on cell cycle

Owing to their unique characteristics, nanoparticles (NPs) could be incorporated into valuable therapeutic modalities for different diseases; however, there are many concerns about risk factors in human applications. NPs carry therapeutic chemicals that could improve the outcome of cancer therapies. Nowadays, NPs are being recognized as important and strategic agents in treatment of several disorders due to their unique properties in targeting malignant cells in tumor sites. Numerous investigations have shown that the majority of chemotherapeutic agents can be modified through entrapment in submicron colloidal systems. Still, there are problems and limitations in application of NPs in cancer therapy. The aim of the present study is to focus on potential NPs usage in cancer treatment with an emphasis on the cell cycle of malignant cells.

In Vitro Antitumor Potential of Sulfated Polysaccharides from Seaweed Caulerpa cupressoides var. flabellata

Seaweeds are important source of bioactive compounds, including sulfated polysaccharides (SP). Because of their structural heterogeneity, these compounds are promising sources of anticancer compounds. SP from brown and red seaweeds have shown antimelanoma activity in different in vitro and in vivo models. However, SP from green seaweed are still poorly evaluated. Therefore, SP were extracted from the green alga Caulerpa cupressoides var. flabellata, and their antiproliferative, anti-migratory, and inhibitory effect on melanin production on B16-F10 melanoma cells was evaluated. Cell assays, including flow cytometry, demonstrated that SP (100-1000 μg mL^-1) are non-cytotoxic, do not induce apoptosis or necrosis, and do not interfere with cell cycle. However, SP (1000 μg mL^-1) were found to significantly inhibit cell colony formation (80-90%), cell migration (40-75%), and melanin production (~ 20%). In summary, these results showed that SP inhibited important melanoma development events without cytotoxicity effects, suggesting that C. cupressoides may be an important source of SP with antitumor properties.

Transposable element regulation and expression in cancer

Approximately 45% of the human genome is composed of transposable elements (TEs). Expression of these elements is tightly regulated during normal development. TEs may be expressed at high levels in embryonic stem cells but are epigenetically silenced in terminally differentiated cells. As part of the global 'epigenetic dysregulation' that cells undergo during transformation from normal to cancer, TEs can lose epigenetic silencing and become transcribed, and, in some cases, active. Here, we summarize recent advances detailing the consequences of TE activation in cancer and describe how these understudied residents of our genome can both aid tumorigenesis and potentially be harnessed for anticancer therapies.

Splice Modulation Synergizes Cell Cycle Inhibition

While recognized as a therapeutic target, the spliceosome may offer a robust vector to improve established therapeutics against other protein targets. Here, we describe how modulating the spliceosome using small molecule splice modulators (SPLMs) can prime a cell for sensitivity to a target-specific drug. Using the cell cycle regulators aurora kinase and polo-like kinase as models, this study demonstrates how the combination of SPLM treatment in conjunction with kinase inhibition offers synergy for antitumor activity using reduced, sublethal levels of SPLM and kinase inhibitors. This concept of splice-modulated drug attenuation suggests a possible approach to enhance therapeutic agents that have shown limited applicability due to high toxicity or low efficacy.

Cytotoxicity and Anti-inflammatory Properties of Apigenin-Derived Isolaxifolin

The rare flavonoid isolaxifolin, a potent insecticide, has been touted as a potential grain-protecting agent. In order to assess any impact of this natural product on human health and to explore its various other biological properties, we have established a semisynthesis from the simpler but structurally related and more abundant natural product apigenin. The five-step reaction sequence has provided, for the first time, sufficient material for an in-depth evaluation of the cytotoxic properties of the title natural product. The impact of isolaxifolin on certain pro-inflammatory cytokines in murine macrophage RAW 264.7 cells has also been examined. Such studies have revealed that isolaxifolin displays no toxic effects toward normal cells while displaying greater cytotoxicities against certain cancer cell lines than its synthetic precursor apigenin. Furthermore, unlike apigenin, isolaxifolin only reduced NO, TNF-α, and IL-6 secretions in LPS-induced RAW 264.7 cells in a rather modest and dose-independent manner.

Downregulation of miR-144 by triptolide enhanced p85α-PTEN complex formation causing S phase arrest of human nasopharyngeal carcinoma cells

Selective pharmacologic targeting of cell cycle regulators is a potent anti-cancer therapeutic strategy. Here, we show that caspase-3-mediated p21 cleavage involves p53 independent of triptolide (TPL)-induced S phase arrest in human type 1 nasopharyngeal carcinoma (NPC) cells. Coimmunoprecipitation studies demonstrated that TPL causes S phase cell cycle arrest by suppressing the formation of cyclin A-phosphor (p)-cyclin-dependent kinas 2 (CDK2) (Thr 39) complexes. Ectopic expression of constitutively active protein kinase B1 (Akt1) blocks the induction of S phase arrest and the suppression of cyclin A expression and CDK2 Thr 39 phosphorylation by TPL. Expression of the phosphomimetic mutant CDK2 (T39E) rescues the cells from TPL-induced S phase arrest, whereas phosphorylation-deficient CDK2 (T39A) expression regulates cell growth with significant S phase arrest and enhances TPL-triggered S phase arrest. Treatment with TPL induces an increase in the formation of complexes between unphosphorylated phosphatase and tensin homolog deleted from chromosome 10 (PTEN) and p85α in the plasma membrane. Decreased microRNA (miR)-144 expression and increased PTEN expression after TPL treatment were demonstrated, and TPL-enhanced p85α-PTEN complexes and inhibitory effects on Akt (Ser 473) phosphorylation and S phase arrest were suppressed by ectopic PTEN short hairpin RNA or miR-144 expression. Knockdown of endogenous miR-144 by miR-144 Trap upregulated PTEN expression and accordingly enhanced p85α-PTEN complex formation and S phase arrest. Collectively, the effect of TPL on S phase arrest in human NPC cells is likely to enhance the p85α-PTEN interaction in the plasma membrane by suppressing miR-144 expression, resulting in the attenuation of cyclin A-p-CDK2 (Thr 39) complex formation via Akt inactivation.

The Anti-Proliferation, Cycle Arrest and Apoptotic Inducing Activity of Peperomin E on Prostate Cancer PC-3 Cell Line

Peperomin E is a natural secolignan existing distributed in the plants of the genus Peperomia. Previous investigations demonstrated that peperomin E showed potential antitumor activity in some cancer lines, but it is unclear whether peperomin E has an effect on prostate cancer cell lines. The aim of the present study is to investigate its effects on proliferation inhibition, apoptosis-inducing and cell-cycle arrest activity using a prostate cancer PC-3 cell line. The proliferation inhibition was evaluated by MTT assay, apoptosis was detected by Annexin V/propidium iodide (PI) staining and Hoechst 33258 staining, cell cycle distributions were measured by flow cytometry, and western blot analysis was used to determine specific cellular apoptotic protein expressions of Bcl-2, Bax, caspase-3 and cleaved-caspase-3. According to the results of this study, peperomin E exhibited significant anti-proliferation activity on PC-3 cell lines in vitro in a dose-dependent manner. Peperomin E treatments lead to marked morphological changes. Apoptotic cell count and cell-cycle distribution at G2/M phase significantly increased with increasing concentrations of peperomin E. The down-regulated expression level of Bcl-2 and up-regulated expression level of Bax and cleaved-caspase-3 compared with the controls were also observed after peperomin E treatment. These data suggest that peperomin E exhibited proliferation inhabitation, apoptosis-inducing and cell-cycle arrest activity on PC-3 cell lines. The anti-proliferation effect of peperomin E on PC-3 cells should result partly from its cell-cycle arrest and apoptosis-inducing activity, whereas the increasing of the Bax/Bcl-2 ratio and activation of caspases-3 play an important role in the development of apoptosis.

Development and evaluation of a novel series of Nitroxoline-derived BET inhibitors with antitumor activity in renal cell carcinoma

Small molecular inhibitors targeting BRD4 family proteins are emerging as promising therapies in many types of human malignancies. However, whether BRD4, as well as other BET family members, may serve as therapeutic targets in renal cell carcinoma (RCC) remains unknown. In this study, we found that both BRD2 and BRD4 were over-expressed in RCC tissues, knock-down both of which achieved potent anti-proliferative effects in RCC cells. A novel category of BET inhibitors, originated from an approved drug Nitroxoline, were synthesized and evaluated with biochemical and cellular assays, as well as the method of crystallography. The complex crystal structures of several compounds in this category with the first bromodomain of BRD4 (BRD4-BD1) were solved, revealing the binding mechanism and facilitating further structural optimizations. Among them, compound BDF-1253 showed an approximately four-fold improvement in BRD4 inhibition compared with the prototype Nitroxoline and had good selectivity for BET proteins against other bromodomain proteins or epi-enzymes in biochemical assays. Compound BDF-1253 efficiently suppressed the expression of BET downstream genes, impaired RCC cells viability via inducing cell cycle arrest and apoptosis, and decreased tumor growth in RCC xenografts. In summary, these results suggest that inhibition of BET family members has great therapeutic potentials in the treatment of RCC, and the novel series of BET inhibitors reported here are promising to become RCC drug candidates.

Resveratrol analogue, trans-4,4'-dihydroxystilbene (DHS), inhibits melanoma tumor growth and suppresses its metastatic colonization in lungs

The prevalence of melanoma and the lack of effective therapy for metastatic melanoma warrant extensive and systematic evaluations of small molecules in cellular and pre-clinical models. We investigated, herein, the antitumor and anti-metastatic effects of trans-4,4'-dihydroxystilbene (DHS), a natural product present in bark of Yucca periculosa, using in vitro and in vivo melanoma murine models. DHS showed potent melanoma cytotoxicity, as determined by MTT and clonogenic assay. Further, DHS induced cytotoxicity was mediated through apoptosis, which was assessed by annexin V-FITC/PI, sub-G1 and caspase activation assays. In addition, DHS inhibited cell proliferation by inducing robust cell cycle arrest in G1-phase. Imperatively, these inhibitory effects led to a significant reduction of melanoma tumor in pre-clinical murine model. DHS also inhibited cell migration and invasion of melanoma cells, which were examined using wound healing and Transwell migration/invasion assays. Mechanistically, DHS modulated the expressions of several key metastasis regulating proteins e.g., MMP-2/9, N-cadherin, E-cadherin and survivin. We also showed the anti-metastatic effect of DHS in a melanoma mediated lung metastasis model in vivo. DHS significantly reduced large melanoma nodule formation in the parenchyma of lungs. Therefore, DHS may represent a promising natural drug in the repertoire of treatment against melanoma tumor growth and metastasis.

Cell Cycle Arrest and Apoptosis in HT-29 Cells Induced by Dichloromethane Fraction From Toddalia asiatica (L.) Lam

The roots of Toddalia asiatica (L.) Lam. (TA) has been often used in Chinese folk medicine to treat different diseases, including but not limited to arthritis, injuries, stomachache, and even tumors. However, the anti-cancer effects and the action mechanisms of TA remain elusive. Therefore, we firstly evaluated the effects of different extracts of TA on the growth of human colon cancer cells, and then tried to further elucidate their underlying molecular mechanisms. As a result, the dichloromethane fraction (DF) was found to possess the highest anti-proliferative activity with IC50 value at 18 μg/mL among all of the four extracts from TA, and strongly inhibited HT-29 cell growth and halted cell cycle progression in G2/M phase. DF also induced phosphatidylserine externalization and activated caspases -8, -9, and -3, suggesting DF induced apoptosis through intrinsic and extrinsic pathways. Furthermore, we found that HT-29 cell cycle arrest induced by DF could be the result of reactive oxygen species (ROS), as the ROS scavenger N-acetyl cysteine (NAC) attenuating it. Taken together, these results indicated that DF induced cell cycle arrest at G2/M phase and apoptosis in HT-29 cells, and could be a promising source for developing natural therapeutics for colon cancer.

Synthetic α-mangostin dilaurate strongly suppresses wide-spectrum organ metastasis in a mouse model of mammary cancer

We previously reported that, in a mouse model of mammary cancer, α‐mangostin alone exhibits anti‐metastatic properties. To enhance this anti‐metastatic effect, we examined the efficacy of synthetic α‐mangostin dilaurate (MGD), prepared by adding lauric acid to α‐mangostin, in the same experimental system wherein mice bearing mammary tumors are exposed to dietary MGD at 0, 2000 and 4000 ppm. Lauric acid has a high propensity for lymphatic absorption, which is the most common pathway of initial dissemination of many solid malignancies. Both mammary tumor volumes and wide‐spectrum organ metastasis were markedly reduced at 2000 and 4000 ppm: furthermore, survival in the 4000‐ppm group was significantly greater than in control mice. Apoptosis in mammary carcinomas was also significantly increased in the 4000‐ppm group, whereas blood microvessel density and lymphatic vessel invasion were markedly reduced. In real‐time PCR analyses of tumor samples, increased p21 and decreased Pcna expression were observed with 4000 ppm but values were not statistically significant when compared to expression in control tumors. However, exposure to 4000 ppm significantly decreased expression of phospho‐Akt (Ser473/Thr308) as compared to the control, indicating a role in the anti‐tumorigenic effects of MGD. These findings suggest that MGD may be useful for adjuvant therapy and chemoprevention and that conjugated medium‐chain fatty acids may enhance the efficacy of certain chemotherapeutic agents.

In vitro and in vivo anti-tumor activity of CoQ0 against melanoma cells: inhibition of metastasis and induction of cell-cycle arrest and apoptosis through modulation of Wnt/β-catenin signaling pathways

Coenzyme Q₀ (CoQ₀, 2,3-dimethoxy-5-methyl-1,4-benzoquinone), a novel quinone derivative, has been shown to modulate cellular redox balance. However, effect of this compound on melanoma remains unclear. This study examined the in vitro or in vivo anti-tumor, apoptosis, and anti-metastasis activities of CoQ₀ (0-20 μM) through inhibition of Wnt/β-catenin signaling pathway. CoQ₀ exhibits a significant cytotoxic effect on melanoma cell lines (B16F10, B16F1, and A2058), while causing little toxicity toward normal (HaCaT) cells. The suppression of β-catenin was seen with CoQ₀ administration accompanied by a decrease in the expression of Wnt/β-catenin transcriptional target c-myc, cyclin D1, and survivin through GSK3β-independent pathway. We found that CoQ₀ treatment caused G₁ cell-cycle arrest by reducing the levels of cyclin E and CDK4. Furthermore, CoQ₀ treatment induced apoptosis through caspase-9/-3 activation, PARP degradation, Bcl-2/Bax dysregulation, and p53 expression. Notably, non- or sub-cytotoxic concentrations of CoQ₀ markedly inhibited migration and invasion, accompanied by the down-regulation of MMP-2 and -9, and up-regulation of TIMP-1 and -2 expressions in highly metastatic B16F10 cells. Furthermore, the in vivo study results revealed that CoQ₀ treatment inhibited the tumor growth in B16F10 xenografted nude mice. Histological analysis and western blotting confirmed that CoQ₀ significantly decreased the xenografted tumor progression as demonstrated by induction of apoptosis, suppression of β-catenin, and inhibition of cell cycle-, apoptotic-, and metastatic-regulatory proteins. The data suggest that CoQ₀ unveils a novel mechanism by down-regulating Wnt/β-catenin pathways and could be used as a potential lead compound for melanoma chemotherapy.

Eco-Friendly Formulated Zinc Oxide Nanoparticles: Induction of Cell Cycle Arrest and Apoptosis in the MCF-7 Cancer Cell Line

Green products have strong potential in the discovery and development of unique drugs. Zinc oxide nanoparticles (ZnO NPs) have been observed to have powerful cytotoxicity against cells that cause breast cancer. The present study aims to examine the cell cycle profile, status of cell death, and pathways of apoptosis in breast cancer cells (MCF-7) treated with biosynthesized ZnO NPs. The anti-proliferative activity of ZnO NPs was determined using MTT assay. Cell cycle analysis and the mode of cell death were evaluated using a flow cytometry instrument. Quantitative real-time-PCR (qRT-PCR) was employed to investigate the expression of apoptosis in MCF-7 cells. ZnO NPs were cytotoxic to the MCF-7 cells in a dose-dependent manner. The 50% growth inhibition concentration (IC₅₀) of ZnO NPs at 24 h was 121 µg/mL. Cell cycle analysis revealed that ZnO NPs induced sub-G₁ phase (apoptosis), with values of 1.87% at 0 μg/mL (control), 71.49% at IC₂₅, 98.91% at IC₅₀, and 99.44% at IC₇₅. Annexin V/propidium iodide (PI) flow cytometry analysis confirmed that ZnO NPs induce apoptosis in MCF-7 cells. The pro-apoptotic genes p53, p21, Bax, and JNK were upregulated, whereas anti-apoptotic genes Bcl-2, AKT1, and ERK1/2 were downregulated in a dose-dependent manner. The arrest and apoptosis of MCF-7 cells were induced by ZnO NPs through several signalling pathways.

Cytotoxic effect of Erythroxylum daphnites extract is associated with G1 cell cycle arrest and apoptosis in oral squamous cell carcinoma

Plant-derived molecules showing antineoplastic effects have recently gained increased attention as potential adjuvants to traditional therapies for various cancers. Cerrado biome in Brazil contains high floral biodiversity, but knowledge about the potential therapeutic effects of compounds derived from that flora is still limited. The present study investigated the antineoplastic activity of Erythroxylum daphnites Mart., a Brazilian native plant from Cerrado biome, in the SCC-9 oral squamous cell carcinoma cell line. Cells were treated with various concentrations of hexane extract of Erythroxylum daphnites leaves (EDH) and assessed for cytotoxicity, proliferation, and apoptosis. Thin layer chromatography was conducted to characterize the substances present in EDH. Our results showed that EDH exerted anti-proliferative effects in SCC-9 cells by stabilizing the cell cycle at G1 phase in association with reduced intracellular levels of cyclins D and E and increased level of p21. EDH also demonstrated pro-apoptotic properties, as shown by an increased expression of caspase-3. Triterpenes were the major constituents of EDH. Our findings demonstrated a cytotoxic effect of EDH against SCC-9 cells in vitro mediated by the restraint of cellular proliferation and induction of apoptosis. Taken together, these findings support EDH constituents as potential therapeutic adjuvants for oral cancer.

INDUCTION OF CELL CYCLE ARREST AND APOPTOSIS BY ORMENIS ERIOLEPIS A MORROCAN ENDEMIC PLANT IN VARIOUS HUMAN CANCER CELL LINES

Background:

Ormenis eriolepis Coss (Asteraceae) is an endemic Moroccan subspecies, traditionally named “Hellala” or “Fergoga”. It’s usually used for its hypoglycemic effect as well as for the treatment of stomacal pain. As far as we know, there is no scientific exploration of anti tumoral activity of Ormenis eriolepis extracts.

Materials and Methods:

In this regard, we performed a screening of organic extracts and fractions in a panel of both hematological and solid cancer cell lines, to evaluate the potential in vitro anti tumoral activity and to elucidate the respective mechanisms that may be responsible for growth arrest and cell death induction. The plant was extracted using organic solvents, and four different extracts were screened on Jurkat, Jeko-1, TK-6, LN229, SW620, U2OS, PC-3 and NIH3T3 cells.

Results:

Cell viability assays revealed that, the IC50 values were (11,63±5,37μg/ml) for Jurkat, (13,33±1,67μg/ml) for Jeko-1, (41,67±1,98μg/ml) for LN229 and (19,31±4,88μg/ml) for PC-3 cells upon treatment with Oe-DF and Oe-HE respectively. Both the fraction and extract exhibited no effects on TK6 and NIH3T3. Cytometry analysis accompanied by DNA damage signaling protein levels monitoring (p-H2A.X), showed that both the Dichloromethane Fraction and Hexanic extract induce DNA double stranded breaks (DSBs) accompanied by cell cycle arrest in G1 (Jurkat, Jeko -1 and LN22) and G2/M (PC-3) phases which is agreed with the caspase activity observed. Additional experiments with selective inhibitors of stress and survival pathways (JNK, MAPK, Rho, p53, and JAK3) indicated that none of these pathways was significantly involved in apoptosis induction. The bioactive compound analysis by CG/MS indicated that the major compounds in Oe-DF were: Linoleic Acid (15,89%), Podophyllotoxin (17,89%) and Quercetin (22,95%). For Oe-HE the major molecules were: Linoleic Acid (9,76%), α-curcumene (7,07%), α-bisabolol (5,49%), Campesterol (4,41%), Stigmasterol (14,08%) and β-sitosterol (7,49%).

Conclusion:

Our data suggest that bioactive compounds present in Ormenis eriolepis show significant anti proliferative activity inducing cell cycle arrest and cell death operating through apoptosis pathway.

Casearin D inhibits ERK phosphorylation and induces downregulation of cyclin D1 in HepG2 cells

Cancer is a public health problem which represents the second cause of death in the world. In this framework, it is necessary to identify novel compounds with antineoplastic potential. Plants are an important source for discovering novel compounds with pharmacological potential. In this study, we aimed to investigate the antiproliferative potential of isolated compounds from Casearia sylvestris on tumor cell lines. Crude extract effectively reduced cell viability of 4 tumor cell lines (HepG2, A549, U251-MG, and HT-144) after 48h treatment. HepG2 and HT-144 were the most responsive cells. Three fractions (aqueous ethanol, n-hexane and ethyl acetate) were tested against HepG2 and HT-144 cells and we observed that compounds with antiproliferative activity were concentrated in n-hexane and ethyl acetate fractions. The casearins A, G and J were isolated from n-hexane fraction, while casearin D was obtained from ethyl acetate fraction. We demonstrated that casearin D significantly inhibited the clonogenic capacity of HepG2 cells after 24h exposure indicating its antiproliferative activity. In addition, G1/S transition cell cycle arrest in HepG2 cells was also observed. These effects are related, at least in part, to ability of the casearin D in reducing ERK phosphorylation and cyclin D1 expression levels.

Molecular Changes Associated With Tumor Initiation and Progression of Soft Tissue Sarcomas: Targeting the Genome and Epigenome

Soft tissue sarcomas are rare, but generally aggressive tumors which disproportionately affect children and young adults. They represent less than 10% of all cancers, but are one of the most frequently diagnosed cancers in pediatric patients. These cancers have a high rate of morbidity and mortality, and their overall incidence has been increasing at an estimated rate of 26% over the last 2 decades. The cause of this increased incidence is unknown but various environmental factors have been implicated. Establishing standard therapeutic strategies is challenging for soft tissue sarcomas as more than 50 different histological subtypes exist, each with their own molecular alterations and clinical characteristics, and this combination of tumor heterogeneity and a limited number of clinical cases make detailed omics level molecular studies particularly challenging. This chapter will focus on the unique genetic and epigenetic changes which characterize these cancers, with an emphasis on translocation-associated sarcomas involving primary gene fusions with the RNA chaperone protein EWSR1. We will highlight current therapeutic approaches and discuss opportunities for targeted molecular therapeutics.

Efficacy of CDK4 inhibition against sarcomas depends on their levels of CDK4 and p16ink4 mRNA

Sarcomas are malignant tumors accounting for a high percentage of cancer morbidity and mortality in children and young adults. Surgery and radiation therapy are the accepted treatments for most sarcomas; however, patients with metastatic disease are treated with systemic chemotherapy. Many tumors display marginal levels of chemoresponsiveness and new treatment approaches are needed. Deregulation of the G1 checkpoint is crucial for various oncogenic transformation processes, suggesting that many cancer cell types depend on CDK4/6 activity. Thus, CDK4/6 activity appears to represent a promising therapeutic target for cancer treatment. In the present work, we explore the efficacy of CDK4 inhibition using palbociclib (PD0332991), a highly selective inhibitor of CDK4/6, in a panel of sarcoma cell lines and sarcoma tumor xenografts (PDXs). Palbociclib induces senescence in these cell lines and the responsiveness of these cell lines correlated with their levels of CDK4 mRNA. Palbociclib is also active in vivo against sarcomas displaying high levels of CDK4 but not against sarcomas displaying low levels of CDK4 and high levels of p16^ink4a. The analysis of tumors growing after palbociclib showed a clear decrease in the CDK4 levels, indicating that clonal selection occurred in these treated tumors. In summary, our data support the efficacy of CDK4 inhibitors against sarcomas displaying increased CDK4 levels, particularly fibrosarcomas and MPNST. Our results also suggest that high levels of p16^ink4a may indicate poor efficacy of CDK4 inhibitors.

Oleanolic acid inhibits cell survival and proliferation of prostate cancer cells in vitro and in vivo through the PI3K/Akt pathway

Oleanolic acid (OA) is a naturally occurring pentacyclic triterpenoid and possesses diverse pharmacological activities, including anti-cancer effects that have been confirmed in multiple types of human cancers. However, the potential effect of natural OA on human prostate cancer is still unclear. The present study aimed to explore whether and how OA exerted anti-cancer effects in prostate cancer. Our data showed that OA inhibited cell viability and proliferation, and promoted cell apoptosis and G0/G1 phase cell cycle arrest in prostate cancer PC-3, DU145, and LNCaP cells, in a dose-dependent manner. In addition, OA was found to regulate the expression levels of apoptosis-related and cell cycle-related proteins, as well as the activity of PI3K/Akt pathway, in a dose-dependent manner. Mechanistically, our data revealed that OA exerted anti-cancer effects in vitro in PC-3 and DU145 cells by repressing the PI3K/Akt pathway. In agreement, OA also suppressed the tumor growth of PC-3 cells in vivo via inhibition of the PI3K/Akt pathway. In conclusion, our findings demonstrate the anti-cancer properties of OA in prostate cancer cells, both in vitro and in vivo, and provide the experimental evidence for the use of OA as an adjuvant agent for prostate cancer patients.

Adapalene inhibits the activity of cyclin-dependent kinase 2 in colorectal carcinoma

Cyclin-dependent kinase 2 (CDK2) has been reported to be overexpressed in human colorectal cancer; it is responsible for the G1‑to‑S‑phase transition in the cell cycle and its deregulation is a hallmark of cancer. The present study was the first to use idock, a free and open‑source protein‑ligand docking software developed by our group, to identify potential CDK2 inhibitors from 4,311 US Food and Drug Administration‑approved small molecular drugs with a re‑purposing strategy. Among the top compounds identified by idock score, nine were selected for further study. Among them, adapalene (ADA; CD271,6‑[3‑(1‑adamantyl)‑4‑methoxyphenyl]‑2‑naphtoic acid) exhibited the highest anti‑proliferative effects in LOVO and DLD1 human colon cancer cell lines. Consistent with the expected properties of CDK2 inhibitors, the present study demonstrated that ADA significantly increased the G1‑phase population and decreased the expression of CDK2, cyclin E and retinoblastoma protein (Rb), as well as the phosphorylation of CDK2 (on Thr‑160) and Rb (on Ser‑795). Furthermore, the anti‑cancer effects of ADA were examined in vivo on xenograft tumors derived from DLD1 human colorectal cancer cells subcutaneously inoculated in BALB/C nude mice. ADA (20 mg/kg orally) exhibited marked anti‑tumor activity, comparable to that of oxaliplatin (40 mg/kg), and dose‑dependently inhibited tumor growth (P<0.05), while combined administration of ADA and oxaliplatin produced the highest therapeutic effect. To the best of our knowledge, the present study was the first to indicate that ADA inhibits CDK2 and is a potential candidate drug for the treatment of human colorectal cancer.

Antiproliferative and Apoptosis Inducing Effects of Non-Polar Fractions from Lawsonia inermis L. in Cervical (HeLa) Cancer Cells

Two non-polar fractions viz. hexane (Hex-LI) and chloroform fraction (CHCl3-LI) of Lawsonia inermis were studied for their antiproliferative potential in various cancer cell lines viz. HeLa, MCF-7, A549 and C6 glioma cells. Both the fractions showed more than 60 % of growth inhibition in all the tested cell lines at highest tested concentration. In clonogenic assay, different concentrations of Hex-LI and CHCl3-LI decreased the number and size of colonies as compared to control in HeLa cells. The apoptotic effects as nuclear condensation, fragmentation were visualized with Hoechst-33342 staining of HeLa cells using confocal microscope. Both fractions induced apoptotic cell death in human cervical carcinoma (HeLa) cells as evident from flow cytometric analysis carried out using Annexin V-FITC and propidium iodide dyes. CHCl3-LI treated cells significantly induced apoptosis (25.43 %) in comparison to control. Results from Neutral Comet assay demonstrated that both fractions induced double stranded breaks (DSB's) in HeLa cells. Our data indicated that Hex-LI and CHCl3-LI treated cells showed significant increase of 32.2 and 18.56 % reactive oxygen species (ROS) levels in DCFH-DA assay respectively. Further, experimental studies to decipher exact pathway via which these fractions induce cell death are in progress.

Peperotetraphin inhibits the proliferation of human prostate cancer cells via induction of cell cycle arrest and apoptosis

Peperotetraphin (methyl rel-(1R,2S,3S)-2,3-bis(7-methoxy-1,3-benzodioxol-5-yl) cyclobutanecarboxylate) was a novel cyclobutane-type norlignan, which was isolated from the whole plant of Peperomia tetraphylla. In this study, we explored its anti-tumor effect and the molecular mechanism in human prostate cancer PC-3 cell lines. Firstly, cell viability was evaluated by Cell Counting Kit (CCK-8) assay. The PC-3 cells were treated with increasing concentrations of peperotetraphin for 24, 48 and 72 h, respectively. The results showed that peperotetraphin inhibited the growth of PC-3 cell in a dose- and time-dependent manner. Next, the cell cycle distributions were analyzed by flow cytometric analysis (FCM), and the data suggested that peperotetraphin could significantly induce cell cycle arrested at the G1-S phase transition. Then, the cell apoptosis was detected by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and annexin V-FITC/PI dual staining analysis, the data confirmed apoptosis-inducing activity of peperotetraphin and the apoptosis rates increased from 3.9 to 32.3 % when treated with increasing concentrations of peperotetraphin from 0 to 50 µM. The expression levels of apoptosis-regulating protein caspase-3, Bax and Bcl-2 were also analyzed by Western blot analysis. The results showed that the expression levels of Bax and the activity of caspase-3 were upregulated, whereas the expression levels of Bcl-2 were downregulated compared with those of the control. These findings demonstrated that peperotetraphin exhibited effective cell growth inhibition by inducing cancer to undergo G1 phase arrest and apoptosis. The results suggested that peperotetraphin might have potential as chemoprevention or anti-tumor agent to prostatic cancer.

Multiplex imaging and cellular target identification of kinase inhibitors via an affinity-based proteome profiling approach

MLN8237 is a highly potent and presumably selective inhibitor of Aurora kinase A (AKA) and has shown promising antitumor activities. Like other kinase inhibitors which target the ATP-binding site of kinases, MLN8237 might be expected to have potential cellular off-targets. Herein, we report the first photoaffinity-based, small molecule AKA probe capable of both live-cell imaging of AKA activities and in situ proteome profiling of potential off-targets of MLN8237 (including AKA-associating proteins). By using two mutually compatible, bioorthogonal reactions (copper-catalyzed azide-alkyne cycloaddition chemistry and TCO-tetrazine ligation), we demostrate small molecule-based multiplex bioimaging for simultaneous in situ monitoring of two important cell-cycle regulating kinases (AKA and CDK1). A broad range of proteins, as potential off-targets of MLN8237 and AKA's-interacting partners, is subsequently identified by affinity-based proteome profiling coupled with large-scale LC-MS/MS analysis. From these studies, we discover novel AKA interactions which were further validated by cell-based immunoprecipitation (IP) experiments.

Synthesis, cytotoxicity, DNA interaction and cell cycle studies of trans-diiodophosphine Pt(ii) complexes

Diiodido phosphine Pt complexes were synthesized and their biological activity studied. The complex with isopropylamine was the best candidate.

Antitumor effects of two extracts from Oxytropis falcata on hepatocellular carcinoma in vitro and in vivo

AIMS

To investigate the antitumor effects of extracts from Oxytropis falcata on human hepatocellular carcinoma SMMC-7721 cells in vitro and in transplanted murine H22 tumors in vivo.

METHODS

Cell proliferation, cell cycle distribution and apoptosis in SMMC-7721 cells were determined and tumor growth inhibition in H22 tumors was investigated. Cell cycle distribution was analyzed by flow cytometry with propidium iodide (PI) and Annexin V-FITC/ PI double staining.

RESULTS

MTT assay revealed that essential oil and flavonoids of O. falcata (named EOOF and FOF) inhibited proliferation of SMMC-7721 cells in a dose-dependent manner. The IC50 value of EOOF and FOF were 0.115 and 0.097 mg·mL(-1), respectively. Cell cycle was arrested at G(1) phase, and induction of apoptosis occurred in SMMC-7721 cells when subjected to FOF. Growth inhibition in H22 solid tumors transplanted mice was significantly pronounced after being treated with FOF, and the inhibition ratio were 56.1% and 70.8% at the concentration of 30 and 60 mg·kg(-1).

CONCLUSION

The results suggest that FOF promotes apoptosis in SMMC-7721 cells and inhibits H22 tumor growth, resulting in a potential antitumor effect on hepatic cancer.

Chebulagic acid from Terminalia chebula causes G1 arrest, inhibits NFκB and induces apoptosis in retinoblastoma cells

Background

Plants are the valuable source of natural products with important medicinal properties. Most of the approved anti cancer drugs have a natural product origin or are natural products. Retinoblastoma is the most common ocular cancer of children. Although chemotherapy is the preferred mode of therapy, a successful treatment for retinoblastoma requires enucleation. Chebulagic acid (CA) from Terminalia chebula was shown to have anti-proliferative properties in the studies on cancerous cell lines. Due to anti cancer properties of CA and due to limitation in treatment options for retinoblastoma, the present study is undertaken to understand the role of CA on the proliferation of retinoblastoma cells.

Methods

Anti proliferative potential of CA was determined by MTT assay. The expression levels of various cell death mediators in retinoblastoma cells with CA treatment were assessed by Western blotting. Flowcytometer analysis was used to estimate the mitochondrial membrane potential (MMP) and to determine the percentage of cells undergoing apoptosis.

Results

The present study showed CA inhibited the proliferation of retinoblastoma cells in a dose dependent manner. CA modulated MMP, induced release of Cytochrome c, activated caspase 3 and shifted the ratio of BAX and Bcl2 towards cell death. G1 arrest, noticed in CA treated cells, is mediated by the increase in the expression of CDK inhibitor p27. CA treatment also decreased the levels of NFκB in the nucleus. This decrease is mediated by suppression in degradation of IκBα.

Conclusion

CA has shown significant anti proliferative potential on retinoblastoma cells. Our findings clearly demonstrate that CA induces G1 arrest, inhibits NFκB and induces apoptosis of retinoblastoma cells.

Alteration of gene expression profile in hepatocellular carcinoma HepG2 cells with Sp3 downregulation

AIM: To analyze the alteration of gene expression profile in hepatocellular carcinoma cell line HepG2 with Sp3 downregulation.

METHODS: RNA interference was performed to downregulate Sp3 mRNA in HepG2 cells and NimbleGen Human Gene Expression Microarray was used for gene expression profile analysis. Real-time quantitative PCR was employed to confirm the expression of several differentially expressed genes. The cell cycle was analyzed by flow cytometry.

RESULTS: A total of 1789 genes was found to be differentially expressed in HepG2 cells with Sp3 downregulation, including 1007 up-regulated and 782 down-regulated ones. These genes were involved in many cellular biological process such as proliferation, differentiation, programmed death, adhesion, and metabolic process. Real-time quantitative PCR confirmed the alteration of several cell cycle related genes (CCND1, CCNE2, TGFB1, and CDKN2A). Flow cytometry analysis showed that the percentage of cells in G₁ phase increased significantly after Sp3 downregulation.

CONCLUSION: Gene expression profile alters in HepG2 with Sp3 downregulation. Sp3 knockdown induces cell cycle arrest in G₀/G₁ phase in HepG2 cells. Sp3 may play an essential role in the pathogenesis of hepatocellular carcinoma as a transcription factor via regulating cell cycle progression.

Effects of griseofulvin on apoptosis through caspase-3- and caspase-9-dependent pathways in K562 leukemia cells: An in vitro study

BACKGROUND

Griseofulvin, an oral nontoxic antifungal drug, has been reported to possess anticancer effect in human cancer cells, while the mechanisms are not completely understood.

OBJECTIVE

The aim of this study was to investigate the cytotoxic effect of griseofulvin on K562 cells and to understand its underlying molecular pathways.

METHODS

K562 cells were treated with griseofulvin at different concentrations for 24 hours, and the inhibition effect of griseofulvin on K562 cell proliferation was assessed by tetrazolium salt colorimetric assay. Apoptosis was assessed by examining nuclear morphology and quantifying phosphatidylserine externalization, and alterations in cellular morphology were analyzed by laser scanning confocal microscopy for fluorescent analysis. Flow cytometry was used in the analysis of cell cycle, mitochondrial membrane potential, and caspase pathways.

RESULTS

Griseofulvin could inhibit the growth of K562 cells in a dose-dependent manner with a mean (SD) inhibitory concentration of 50% value of 15.38 (1.35) μg/mL compared with untreated controls. Apoptosis was induced in K562 cells (38.35% [2.73%]; P < 0.01) by griseofulvin with the observation of both an increase in phosphatidylserine level and accumulation of chromatin nucleation in griseofulvintreated cells. In addition, cell-cycle analysis using propidium iodide staining suggested a significant G2/M accumulation (increase from mean 17.64% [4.49%] to 48.29 [1.89%]; P < 0.01) as a result of griseofulvin treatment. Flow cytometry analysis found that griseofulvin treatment was associated with the depolarization of the mitochondrial membrane in K562 cells. Furthermore, increased activities of caspase-3 by 22.15-fold (P < 0.01) and caspase-9 by 16.73-fold (P < 0.01) were observed in K562 cells after griseofulvin treatment compared with the untreated control; a decrease of caspase-8 activity was also observed, but the change was not statistically significant.

CONCLUSIONS

These findings suggest that griseofulvin inhibited growth of K562 cells and induced cell apoptosis through cell-cycle arrest and mitochondrial membrane potential decrease as well as caspase-3 and -9 activation. Further testing is needed to evaluate the potential of griseofulvin as a candidate in the chemotherapy of hematologic malignancies.

Senescence bypass in mesenchymal stem cells: a potential pathogenesis and implications of pro-senescence therapy in sarcomas

Cellular senescence is a mechanism that limits the lifespan of somatic cells as the results of replicative proliferation and response to stresses, and that prevents undesired oncogenic changes constituting a barrier against immortalization and tumorigenesis. Mesenchymal stem cells (MSCs) reside in a variety of tissues, and participates in tissue maintenance with their multipotent differentiation ability. MSCs are also considered to be as cells of origin for certain type of sarcomas. We reviewed the mechanisms of cellular senescence in MSCs and hypothesized senescence bypass as the potential pathogenesis for sarcoma development, and proposed the possibility of senescence induction therapy for an alternative treatment strategy against sarcomas, especially cells with the resistance to conventional chemo and radiotherapy including sarcoma stem cells.

Polyphenols as key players for the antileukaemic effects of propolis

Propolis (a bee product) which has a long history of medicinal use by humans has attracted a great deal of research interest in the recent time; this is due to its widely reported biological activities such as antiviral, antifungal, antibacterial, anti-inflammatory, antioxidant, and anticarcinogenic properties. Crude form of propolis and its phenolic contents have both been reported to exhibit antileukaemic effects in various leukaemia cell lines. The ability of the polyphenols found in propolis to arrest cell cycle and induce apoptosis and differentiation in addition to inhibition of cell growth and proliferation makes them promising antileukaemic agents, and hence, they are believed to be a key to the antileukaemic effects of propolis in different types of leukaemia. This paper reviews the molecular bases of antileukaemic activity of both crude propolis and individual polyphenols on various leukaemia cell lines, and it indicates that propolis has the potential to be used in both treatment and prevention of leukaemia. This however needs further evaluation by in vitro, in vivo, and epidemiological studies as well as clinical trials.

Revealing the anti-tumoral effect of Algerian Glaucium flavum roots against human cancer cells

Glaucium flavum (G. flavum) is a plant from the Papaveraceae family native to Algeria where it is used in local traditional medicine to treat warts. G. flavum root crude alkaloid extract inhibited breast cancer cell proliferation and induced G2/M phase cycle arrest and apoptosis without affecting normal cells, which is a highly awaited feature of potential anti-cancer agents. G. flavum significantly reduced growth and vascularization of human glioma tumors on chicken chorioallantoic membrane (CAM) in vivo. The chromatographic profile of the dichloromethane extract of G. flavum root showed the presence of different constituents including the isoquinoline alkaloid protopine, as the major compound. We report for the first time that G. flavum extract may represent a new promising agent for cancer chemotherapy.

Ethyl acetate extract of the Mauritian sponge Jaspis sp. induces cell arrest in human promyelocytic leukemia cells

Marine sponges are considered as a gold mine of new natural products possessing numerous biological activities. We examined the cytotoxic properties of the ethyl acetate extract (JDE) of the previously unrecorded sponge, Jaspis sp. collected from Mauritius Waters. JDE displayed an interesting IC50 of 0.057±0.04μg/mL on HL-60 cells evaluated by MTS assay. Mitochondrial membrane potential change, microscopic analysis and DNA fragmentation assays also confirmed JDE induced apoptosis on HL-60 cells. Annexin V staining demonstrated that JDE induced apoptosis at different concentrations. Treatment with 100ng/mL of JDE led to an accumulation of cells in G2/M phase after 24 h, causing a significant increase of cells (24h: 5.84%; 48h: 13.41%) in sub-G1 phase suggesting that JDE can induce cell cycle arrest in G2/M phase.

A review of molecular mechanisms of the anti-leukemic effects of phenolic compounds in honey

Hematologic malignancies constitute about 9% of all new cases of cancers as reported via the GLOBOCAN series by International Agency for Research on Cancer (IARC) in 2008. So far, the conventional therapeutic and surgical approaches to cancer therapy have not been able to curtail the rising incidence of cancers, including hematological malignancies, worldwide. The last decade has witnessed great research interest in biological activities of phenolic compounds that include anticancer, anti-oxidation and anti-inflammation, among other things. A large number of anticancer agents combat cancer through cell cycle arrest, induction of apoptosis and differentiation, as well as through inhibition of cell growth and proliferation, or a combination of two or more of these mechanisms. Various phenolic compounds from different sources have been reported to be promising anticancer agents by acting through one of these mechanisms. Honey, which has a long history of human consumption both for medicinal and nutritional uses, contains a variety of phenolic compounds such as flavonoids, phenolic acids, coumarins and tannins. This paper presents a review on the molecular mechanisms of the anti-leukemic activity of various phenolic compounds on cell cycle, cell growth and proliferation and apoptosis, and it advocates that more studies should be conducted to determine the potential role of honey in both chemoprevention and chemotherapy in leukemia.

DAMTC regulates cytoskeletal reorganization and cell motility in human lung adenocarcinoma cell line: an integrated proteomics and transcriptomics approach

DAMTC (7,8-diacetoxy-4-methylcoumarin) is a thioderivative of 4-methyl coumarin, and previously we have shown that DAMTC is a potent inhibitor of cell growth and an inducer of apoptosis in non-small cell lung cancer (A549) cells. It induces apoptosis through mitochondrial pathway by modulating NF-κB, mitogen-activated protein kinase (MAPK) and p53 pathways. Herein, we explored the genome-wide effects of DAMTC in A549 cells using the concerted approach of transcriptomics and proteomics. In addition to apoptotic pathways, which have been validated earlier, the bioinformatic analysis of microarray data identified small GTPase-mediated signal transduction among the significantly altered biological processes. Interestingly, we observed significant downregulation of some members of the Rho family GTPases in the proteomics data too. Downregulation of Rho GTPases (RhoGDIα (Rho GDP dissociation inhibitor-α, also known as ARHGDIA), Ras homolog family member A, Ras-related C3 botulinum toxin substrate 1 and cell division cycle 42) was validated by western blotting. The Rho protein family is implicated in maintaining the actin filament assembly and cell motility, and we also observed that DAMTC treatment causes actin cytoskeletal reorganization, promotes filopodia formation and inhibits cell motility in A549 cells. The effect of DAMTC treatment on cytoskeleton was reversed after the overexpression of RhoGDIα. In addition, DAMTC augmented the apoptotic effect of etoposide, a proapoptotic chemotherapeutic drug. This elucidation of the mechanism behind DAMTC-induced apoptosis and inhibition of cell motility in A549 cells may make it a potential therapeutic for lung cancer.