Molecular mechanisms of apoptosis and roles in cancer development and treatment

Molecular Mechanisms of Antiproliferative Effects of Natural Chalcones

Simple Summary

Despite the important progress in cancer treatment in the past decades, the mortality rates in some types of cancer have not significantly decreased. Therefore, the search for novel anticancer drugs has become a topic of great interest. Chalcones, precursors of flavonoid synthesis in plants, have been documented as natural compounds with pleiotropic biological effects including antiproliferative/anticancer activity. This article focuses on the knowledge on molecular mechanisms of antiproliferative action of chalcones and draws attention to this group of natural compounds that may be of importance in the treatment of cancer disease.

Abstract

Although great progress has been made in the treatment of cancer, the search for new promising molecules with antitumor activity is still one of the greatest challenges in the fight against cancer due to the increasing number of new cases each year. Chalcones (1,3-diphenyl-2-propen-1-one), the precursors of flavonoid synthesis in higher plants, possess a wide spectrum of biological activities including antimicrobial, anti-inflammatory, antioxidant, and anticancer. A plethora of molecular mechanisms of action have been documented, including induction of apoptosis, autophagy, or other types of cell death, cell cycle changes, and modulation of several signaling pathways associated with cell survival or death. In addition, blockade of several steps of angiogenesis and proteasome inhibition has also been documented. This review summarizes the basic molecular mechanisms related to the antiproliferative effects of chalcones, focusing on research articles from the years January 2015–February 2021.

Induced Cell Death as a Possible Pathway of Antimutagenic Action

The existing concepts of antimutagenesis are briefly reviewed. Published reports on antimutagenic and proapoptotic properties of some polyphenols and compounds of other chemical groups obtained in representative in vitro and in vivo experiments on eukaryotic test systems are discussed. The relationships between the antimutagenic and proapoptotic properties of the analyzed compounds (naringin, apigenin, resveratrol, curcumin, N-acetylcysteine, etc.) are considered in favor of the hypothesis on induced cell death as an antimutagenic tool.

DPP3/CDK1 contributes to the progression of colorectal cancer through regulating cell proliferation, cell apoptosis, and cell migration

At present, colorectal cancer (CRC) has become a serious threat to human health in the world. Dipeptidyl peptidase 3 (DPP3) is a zinc-dependent hydrolase that may be involved in several physiological processes. However, whether DPP3 affects the development and progression of CRC remains a mystery. This study is the first to demonstrate the role of DPP3 in CRC. Firstly, the results of immunohistochemistry analysis showed the upregulation of DPP3 in CRC tissues compared with normal tissues, which is statistically analyzed to be positively correlated with lymphatic metastasis, pathological stage, positive number of lymph nodes. Moreover, the high expression of DPP3 predicts poor prognosis in CRC patients. In addition, the results of cell dysfunction experiments clarified that the downregulation of DPP3 significantly inhibited cell proliferation, colony formation, cell migration, and promoted apoptosis in vitro. DPP3 depletion could induce cell apoptosis by upregulating the expression of BID, BIM, Caspase3, Caspase8, HSP60, p21, p27, p53, and SMAC. In addition, downregulation of DPP3 can reduce tumorigenicity of CRC cells in vivo. Furthermore, CDK1 is determined to be a downstream target of DPP3-mediated regulation of CRC by RNA-seq, qPCR, and WB. The interaction between DPP3 and CDK1 shows mutual regulation. Specifically, downregulation of DPP3 can accentuate the effects of CDK1 knockdown on the function of CRC cells. Overexpression of CDK1 alleviates the inhibitory effects of DPP3 knockdown in CRC cells. In summary, DPP3 has oncogene-like functions in the development and progression of CRC by targeting CDK1, which may be an effective molecular target for the prognosis and treatment of CRC.

Phosphatidylinositol 3-kinase (PI3K) inhibitors: a recent update on inhibitor design and clinical trials (2016-2020)

Introduction: The phosphatidylinositol 3-kinase/protein kinase-B/mammalian target of rapamycin (PI3K/AKT/mTOR) signaling pathway plays a central role in regulating cell growth and proliferation and thus has been considered as effective anticancer drug targets. Many PI3K inhibitors have been developed and progressed to various stages of clinical trials, and some have been approved as anticancer treatment. In this review, we discuss the drug design and clinical development of PI3K inhibitors over the past 4 years. We review the selectivity and potency of 47 PI3K inhibitors. Structural determinants for increasing selectivity toward PI3K subtype-selectivity or mutant selectivity are discussed. Future research direction and current clinical development in combination therapy of inhibitors involved in PI3Ks are also discussed.Area covered: This review covers clinical trial reports and patent literature on PI3K inhibitors and their selectivity published between 2016 and 2020.Expert opinion: To PI3Kα mutants (E542K, E545K, and H1047R), it is highly desirable to design and develop mutant-specific PI3K inhibitors. It is also necessary to develop subtype-selective PI3Kα inhibitors to minimize toxicity. To reduce drug resistance and to improve efficacy, future studies should include combination therapy of PI3K inhibitors with existing anticancer drugs from different pathways.

Endometriosis and Cancer: Exploring the Role of Macrophages

Endometriosis and cancer have much in common, notably their burgeoning of cells in hypoxic milieus, their invasiveness, and their capacity to trigger remodeling, vascularization, and innervation of other tissues. An important role in these processes is played by permissive microenvironments inhabited by a variety of stromal and immune cells, including macrophages. Remarkable phenotypical plasticity of macrophages makes them a promising therapeutic target; some key issues are the range of macrophage phenotypes characteristic of a particular pathology and the possible manners of its modulation. In both endometriosis and cancer, macrophages guard the lesions from immune surveillance while promoting pathological cell growth, invasion, and metastasis. This review article focuses on a comparative analysis of macrophage behaviors in endometriosis and cancer. We also highlight recent reports on the experimental modulation of macrophage phenotypes in preclinical models of endometriosis and cancer.

β-Glucan: A dual regulator of apoptosis and cell proliferation

β-Glucans are polysaccharides generally obtained from the cell wall of bacteria, fungi, yeasts, and aleurone layer of cereals. β-Glucans are polymers, with β-1,3 glucose as core linear structure, but they differ in their main branch length, linkages and branching patterns, giving rise to high and low-molecular-weight β-glucans. They are well-known cell response modifiers with immune-modulating, nutraceutical and health beneficial effects, including anticancer and pro-apoptotic properties. β-Glucan extracts have shown positive responses in controlling tumor cell proliferation and activation of the immune system. The immunomodulatory action of β-glucans enhances the host's antitumor defense against cancer. In consonance with the above, many studies have shown that β-glucan treatment leads to the induction of apoptotic death of cancer cells. The ability of β-glucans to stimulate apoptotic pathways or the proteins involved in apoptosis prompting a new domain in cancer therapy. β-glucan can be a potential therapeutic agent for the treatment of cancer. However, there is a need to legitimize the β-glucan type, as most of the studies include β-glucan from different sources having different physicochemical properties. The body of literature presented here focuses on the effects of β-glucan on immunomodulation, proliferation, cell death and the possible mechanisms and pathways involved in these processes.

Iridin Induces G2/M Phase Cell Cycle Arrest and Extrinsic Apoptotic Cell Death through PI3K/AKT Signaling Pathway in AGS Gastric Cancer Cells

Iridin is a natural flavonoid found in Belamcanda chinensis documented for its broad spectrum of biological activities like antioxidant, antitumor, and antiproliferative effects. In the present study, we have investigated the antitumor potential of iridin in AGS gastric cancer cells. Iridin treatment decreases AGS cell growth and promotes G2/M phase cell cycle arrest by attenuating the expression of Cdc25C, CDK1, and Cyclin B1 proteins. Iridin-treatment also triggered apoptotic cell death in AGS cells, which was verified by cleaved Caspase-3 (Cl- Caspase-3) and poly ADP-ribose polymerase (PARP) protein expression. Further apoptotic cell death was confirmed by increased apoptotic cell death fraction shown in allophycocyanin (APC)/Annexin V and propidium iodide staining. Iridin also increased the expression of extrinsic apoptotic pathway proteins like Fas, FasL, and cleaved Caspase-8 in AGS cells. On the contrary, iridin-treated AGS cells did not show variations in proteins related to an intrinsic apoptotic pathway such as Bax and Bcl-xL. Besides, Iridin showed inhibition of PI3K/AKT signaling pathways by downregulation of (p-PI3K, p-AKT) proteins in AGS cells. In conclusion, these data suggest that iridin has anticancer potential by inhibiting PI3K/AKT pathway. It could be a basis for further drug design in gastric cancer treatment.

Phytochemicals as a Complement to Cancer Chemotherapy: Pharmacological Modulation of the Autophagy-Apoptosis Pathway

Bioactive plant derived compounds are important for a wide range of therapeutic applications, and some display promising anticancer properties. Further evidence suggests that phytochemicals modulate autophagy and apoptosis, the two crucial cellular pathways involved in the underlying pathobiology of cancer development and regulation. Pharmacological targeting of autophagy and apoptosis signaling using phytochemicals therefore offers a promising strategy that is complementary to conventional cancer chemotherapy. In this review, we sought to highlight the molecular basis of the autophagic-apoptotic pathway to understand its implication in the pathobiology of cancer, and explore this fundamental cellular process as a druggable anticancer target. We also aimed to present recent advances and address the limitations faced in the therapeutic development of phytochemical-based anticancer drugs.

LINC02308 promotes the progression of glioma through activating mTOR/AKT-signaling pathway by targeting miR-30e-3p/TM4SF1 axis

BACKGROUND

Glioma is a common brain malignancy, and the purpose of this study is to investigate the function of LINC02308 in glioma.

METHODS

The differentially expressed lncRNAs were screened by microarray. The expression of LINC02308 in glioma tissues and cells was evaluated. The interaction among LINC02308, miR-30e-3p, and TM4SF1 was determined. Cell proliferation and apoptosis were evaluated. The expression of mTOR/AKT-signaling and apoptosis-related markers was detected by Western blot. A xenograft tumor mouse model was constructed to investigate the roles of LINC02308.

RESULTS

LINC02308 was significantly overexpressed in glioma, and a high LINC02308 level was correlated with a poor prognosis. LINC02308 silencing markedly inhibited proliferation and reduced apoptosis of glioma cells and also suppressed tumor growth in the xenograft tumor mouse model. Finally, we demonstrated that LINC02308 played its oncogenic role through binding to miR-30e-3p so as to relieve miR-30e-3p-induced suppression of TM4SF1.

CONCLUSIONS

LINC02308 promoted glioma tumorigenesis as a sponge of miR-30e-3p to upregulate TM4SF1 and activate AKT/mTOR pathway. Graphical Abstract Hypothesis diagram illustrates the function and mechanism of LINC02308 in glioma. A schematic representation of the functional mechanism of LINC02308 in glioma.

HDAC6 inhibitor WT161 performs anti-tumor effect on osteosarcoma and synergistically interacts with 5-FU

BACKGROUND

WT161, as a selective HDAC6 inhibitor, has been shown to play anti-tumor effects on several kinds of cancers. The aim of the present study is to explore the roles of WT161 in osteosarcoma and its underlying mechanisms.

METHODS

The anti-proliferative effect of WT161 on osteosarcoma cells was examined using MTT assay and colony formation assay. Cell apoptosis was analyzed using flow cytometer. The synergistic effect was evaluated by isobologram analysis using CompuSyn software. The osteosarcoma xenograft models were established to evaluate the anti-proliferative effect of WT161 in vivo.

RESULTS

WT161 suppressed the cell growth and induced apoptosis of osteosarcoma cells in a dose- and time-dependent manner. Mechanistically, we found that WT161 treatment obviously increased the protein level of PTEN and decreased the phosphorylation level of protein kinase-B (AKT). More importantly, WT161 showed synergistic inhibition with 5-FU on osteosarcoma cells in vitro and in vivo.

CONCLUSIONS

These results indicate that WT161 inhibits the growth of osteosarcoma through PTEN and has a synergistic efficiency with 5-FU.

Galangin Inhibits Gastric Cancer Growth Through Enhancing STAT3 Mediated ROS Production

Galangin, a flavonoid isolated from the rhizome of Alpinia officinarum (Hance), exerts anticancer activities against many cancer cells such as liver cancer, breast cancer, lung cancer and esophageal cancer. However, the effect, as well as the underlying molecular mechanism of galangin on gastric cancer remains to be elucidated. In the present study, galangin inhibited cell viability of MGC 803 cells but not normal gastric mucosal epithelial GES-1 cells. It suppressed cell proliferation accompanied by reduced Ki67 and PCNA expression, promoted apoptosis shown by decreased Bcl-2 and elevated cleaved caspase-3 and cleaved PARP. And, galangin significantly inactivated JAK2/STAT3 pathway. When STAT3 was overexpressed, the proliferation inhibition and apoptosis promotion induced by galangin were abrogated. Meanwhile, galangin increased ROS accumulation, and reduced Nrf2 and NQO-1, but elevated HO-1 in MGC 803 cells. NAC, a ROS scavenger, rescued ROS over-accumulation and proliferation inhibition of galangin. STAT3 overexpression also counteracted excessive ROS accumulation induced by galangin. Consistent with the in vitro experiments, in nude mice exnografted with MGC 803 cells, galangin inhibited tumor growth and reversed the abnormally expressed proteins, such as p-JAK2, p-STAT3, Bcl-2, cleaved caspase-3, cleaved PARP, and Ki67. Taken together, galangin was suggested to inhibit the growth of MGC 803 cells through inducing apoptosis and decreasing cell proliferation, which might be mediated by modulating STAT3/ROS axis. Our findings implicate a potential application of galangin for gastric cancer therapy possibly with low toxicity.

Lansoprazole Alone or in Combination With Gefitinib Shows Antitumor Activity Against Non-small Cell Lung Cancer A549 Cells in vitro and in vivo

Lansoprazole (Lpz) is an FDA-approved proton pump inhibitor (PPI) drug for the therapy of acid-related diseases. Aiming to explore the new application of old drugs, we recently investigated the antitumor effect of Lpz. We demonstrated that the PPI Lpz played a tumor suppressive role in non-small cell lung cancer (NSCLC) A549 cells. Mechanistically, Lpz induced apoptosis and G0/G1 cell cycle arrest by inhibiting the activation of signal transducer and activator of transcription (Stat) 3 and the phosphoinositide 3-kinase (PI3K)/Akt and Raf/ERK pathways. In addition, Lpz inhibited autophagy by blocking the fusion of autophagosomes with lysosomes. Furthermore, Lpz in combination with gefitinib (Gef) showed a synergistic antitumor effect on A549 cells, with enhanced G0/G1 cell cycle arrest and apoptosis. The combination inhibited Stat3 phosphorylation, PI3K/Akt and Raf/ERK signaling, affecting cell cycle-related proteins such as p-Rb, cyclin D1 and p27, as well as apoptotic proteins such as Bax, Bcl-2, caspase-3, and poly (ADP-ribose) polymerase (PARP). In vivo, coadministration with Lpz and Gef significantly attenuated the growth of A549 nude mouse xenograft models. These findings suggest that Lpz might be applied in combination with Gef for NSCLC therapy, but further evidence is required.

Evaluation of the Potential Diagnostic Utility of the Determination of Selected Caspases-Markers Involved in the Regulation of Apoptosis-In Patients with Ovarian Cancer

Ovarian cancer remains a major diagnostic and therapeutic problem in modern gynecological oncology. For this reason, research which focuses on the search for new diagnostic markers and the assessment of their possible usefulness in clinical practice is still being conducted. The aim of this study was to evaluate serum levels of caspase-3, caspase-8, and caspase-9 in women with ovarian cancer. Patients with ovarian serous cystadenoma (Cystadenoma serosum) and papillary serous cystadenocarcinoma (Cystadenocarcinoma papillare serosum IIIC) were included in the study, as well as healthy women who constituted the control group. The results of the study revealed a statistically significantly decreased mean serum levels of caspase-3, caspase-8, and caspase-9 in women with ovarian cancer as compared to the control group (p ˂ 0.001), which indicates the involvement of the studied parameters in immune system disturbances occurring in the process of apoptosis by the extrinsic and intrinsic pathway and may be one of the mechanisms of immunosuppression accompanying these tumors. Determination of serum levels of examined caspases and CA 125 antigen in women with ovarian cancer in combination with other markers may prove useful in the future in the diagnosis of ovarian cancer, but this requires further studies.

The Road of Solid Tumor Survival: From Drug-Induced Endoplasmic Reticulum Stress to Drug Resistance

Endoplasmic reticulum stress (ERS), which refers to a series of adaptive responses to the disruption of endoplasmic reticulum (ER) homeostasis, occurs when cells are treated by drugs or undergo microenvironmental changes that cause the accumulation of unfolded/misfolded proteins. ERS is one of the key responses during the drug treatment of solid tumors. Drugs induce ERS by reactive oxygen species (ROS) accumulation and Ca²⁺ overload. The unfolded protein response (UPR) is one of ERS. Studies have indicated that the mechanism of ERS-mediated drug resistance is primarily associated with UPR, which has three main sensors (PERK, IRE1α, and ATF6). ERS-mediated drug resistance in solid tumor cells is both intrinsic and extrinsic. Intrinsic ERS in the solid tumor cells, the signal pathway of UPR-mediated drug resistance, includes apoptosis inhibition signal pathway, protective autophagy signal pathway, ABC transporter signal pathway, Wnt/β-Catenin signal pathway, and noncoding RNA. Among them, apoptosis inhibition is one of the major causes of drug resistance. Drugs activate ERS and its downstream antiapoptotic proteins, which leads to drug resistance. Protective autophagy promotes the survival of solid tumor cells by devouring the damaged organelles and other materials and providing new energy for the cells. ERS induces protective autophagy by promoting the expression of autophagy-related genes, such as Beclin-1 and ATG5–ATG12. ABC transporters pump drugs out of the cell, which reduces the drug-induced apoptosis effect and leads to drug resistance. In addition, the Wnt/β-catenin signal pathway is also involved in the drug resistance of solid tumor cells. Furthermore, noncoding RNA regulates the ERS-mediated survival and death of solid tumor cells. Extrinsic ERS in the solid tumor cells, such as ERS in immune cells of the tumor microenvironment (TME), also plays a crucial role in drug resistance by triggering immunosuppression. In immune system cells, ERS in dendritic cells (DCs) and myeloid-derived suppressor cells (MDSCs) influences the antitumor function of normal T cells, which results in immunosuppression. Meanwhile, ERS in T cells can also cause impaired functioning and apoptosis, leading to immunosuppression. In this review, we highlight the core molecular mechanism of drug-induced ERS involved in drug resistance, thereby providing a new strategy for solid tumor treatment.

GSG2 knockdown suppresses cholangiocarcinoma progression by regulating cell proliferation, apoptosis and migration

Cholangiocarcinoma (CCA) is the second most common type of hepatocellular carcinoma characterized by high aggressiveness and extremely poor patient prognosis. The germ cell-specific gene 2 protein (GSG2) is a histone H3 threonine-3 kinase required for normal mitosis. Nevertheless, the role and mechanism of GSG2 in the progression and development of CCA remain elusive. In the present study, the association between GSG2 and CCA was elucidated. Firstly, we demonstrated that GSG2 was overexpressed in CCA specimens and HCCC-9810 and QBC939 cells by immunohistochemical (IHC) staining. It was further revealed that high expression of GSG2 in CCA had significant clinical significance in predicting disease deterioration. Subsequently, cell proliferation, apoptosis, cell cycle distribution and migration were measured by MTT, flow cytometry, and wound healing assays, respectively in vitro. The results demonstrated that downregulation of GSG2 decreased proliferation, promoted apoptosis, arrested the cell cycle and weakened migration in the G2 phase of CCA cells. Additionally, GSG2 knockdown inhibited CCA cell migration by suppressing epithelial-mesenchymal transition (EMT)-related proteins, such as N-cadherin and vimentin. Mechanistically, GSG2 exerted effects on CCA cells by modulating the PI3K/Akt, CCND1/CDK6 and MAPK9 signaling pathways. In vivo experiments further demonstrated that GSG2 knockdown suppressed tumor growth. In summary, GSG2 was involved in the progression of CCA, suggesting that GSG2 may be a potential therapeutic target for CCA patients.

The effects of MEX3A knockdown on proliferation, apoptosis and migration of osteosarcoma cells

Background

Osteosarcoma is an aggressive malignant tumor which has attracted worldwide attention. MEX3A may be associated with tumors while has not yet seen its coverage on osteosarcoma. Herein, this study was to investigate the correlation between MEX3A and the progression of osteosarcoma.

Methods

Firstly, we determined that expression of MEX3A was significantly higher in osteosarcoma tissues than that in marginal bone by immunohistochemical staining. Additionally, MEX3A expression was downregulated by the RNAi‐mediated knockdown. The functions of MEX3A knockdown on proliferation, apoptosis, cell cycle, migration was assessed by MTT assay, flow cytometry, wound-healing assay and Transwell assay, respectively. Knockdown of MEX3A resulted in suppressing cell proliferation, increasing cell apoptosis, inducing the G2 phase cell cycle arrest, and attenuating cellular migration. Furthermore, mouse xenograft model confirmed inhibitory effects of MEX3A knockdown on osteosarcoma formation.

Results

The preliminary exploration on the molecular mechanism of MEX3A in osteosarcoma cells showed that the induction of apoptosis needs the participation of a series of apoptosis- associated factors, such as upregulation of Caspase 3, Caspase 8 and HSP60, downregulation of HSP27 and XIAP.

Conclusions

In summary, these findings predicated that therapy directed at decreasing MEX3A expression is a potential osteosarcoma treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-01882-3.

The molecular mechanism of a novel derivative of BTO-956 induced apoptosis in human myelomonocytic lymphoma cells

Acute myeloid leukemia (AML) is a malignant cancer of the hematopoietic system. Although the effectiveness of arsenic compounds has been recognized and applied clinically, some patients are still found resistant to this chemotherapy. In this study, we investigated that a synthetic thyroid hormone analog (TA), 2-iodo-4-nitro-1-(o-tolyloxy) benzene, had a strong apoptosis effect on U937 cells. U937 cells were treated with TA, and examinted the generation of reactive oxygen species (ROS), dysfunction of mitochondria, expression of pro-apoptosis and anti-apoptosis, and cleavage of caspase-3 and Poly (ADP-ribose) polymerase (PARP). Further, it is also evaluated that insight molecular mechanism and signaling pathways involved in the study. It is found that TA significantly induced apoptosis in U937 cells through production of ROS, dysfunction of mitochondria, and activation of caspase cascade. It was also observed that MAPK signaling pathway including ERK, JNK, and P38 signals are involved in the induction of apoptosis. Moreover, marked activation of autophagy and ER stress markers such as LC3, P62, Beclin1 and GRP78, CHOP were observed, respectively. Pretreatment with ER stress inhibitor tauroursodeoxycholic acid (TUDCA) and autophagy inhibitor 3-Methyladenine (3-MA) have successfully attenuated and aggravated TA-induced apoptosis, respectively. We further confirmed the active involvement of ER stress and autophagy signals. In conclusion, TA induced apoptosis through ER stress and activation of autophagy, and the latter is not conducive to TA-induced cell death. Our results may provide a new insight into the strategic development of novel therapy for the treatment of AML.

Differential roles of farnesoid X receptor (FXR) in modulating apoptosis in cancer cells

Cancer is one of the leading causes of mortality in the world. The conventional treatment strategies of cancer are surgery, radiation, and chemotherapy. However, in the advanced stage of the disease chemotherapy is the prime treatment and it is effective in only less than 10% of the patients. Therefore, there is an urgent need to find out novel therapeutic targets and delineate the mechanism of action of these targets for better management of this disease. Recent studies have shown that some of the proteins have differential role in different cancers. Therefore, it is pertinent that the targeting of these proteins should be based on the type of cancer. The nuclear receptor, FXR, is one of the vital proteins that regulate cell apoptosis. Besides, it also regulates other processes such as cell proliferation, angiogenesis, invasion, and migration. Studies suggest that the low or high expression of FXR is associated with the progression of carcinogenesis depending on the cancer types. Due to the diverse expression, it functions as both tumor suppressor and promoter. Previous studies suggest the overexpression of FXR in breast, lung, esophageal, and prostate cancer, which is related to poor survival and poor prognosis in patients. Therefore, targeting FXR with agonists and antagonists play different outcome in different cancers. Hence, this review describes the role of FXR in different cancers and the role of its inhibitors and activators for the prevention and treatment of various cancers.

From Cell Death to Regeneration: Rebuilding After Injury

The ability to regrow lost or damaged tissues is widespread, but highly variable among animals. Understanding this variation remains a challenge in regeneration biology. Numerous studies from Hydra to mouse have shown that apoptosis acts as a potent and necessary mechanism in regeneration. Much is known about the involvement of apoptosis during normal development in regulating the number and type of cells in the body. In the context of regeneration, apoptosis also regulates cell number and proliferation in tissue remodeling. Apoptosis acts both early in the process to stimulate regeneration and later to regulate regenerative patterning. Multiple studies indicate that apoptosis acts as a signal to stimulate proliferation within the regenerative tissues, producing the cells needed for full regeneration. The conservation of apoptosis as a regenerative mechanism demonstrated across species highlights its importance and motivates the continued investigation of this important facet of programmed cell death. This review summarizes what is known about the roles of apoptosis during regeneration, and compares regenerative apoptosis with the mechanisms and function of apoptosis in development. Defining the complexity of regenerative apoptosis will contribute to new knowledge and perspectives for understanding mechanisms of apoptosis induction and regulation.

Molecular Action of Polyphenols in Leukaemia and Their Therapeutic Potential

Leukaemia is a malignant disease of the blood. Current treatments for leukaemia are associated with serious side-effects. Plant-derived polyphenols have been identified as potent anti-cancer agents and have been shown to work synergistically with standard chemotherapy agents in leukaemia cell lines. Polyphenols have multiple mechanisms of action and have been reported to decrease cell proliferation, arrest cell cycle and induce apoptosis via the activation of caspase (3, 8 and 9); the loss of mitochondrial membrane potential and the release of cytochrome c. Polyphenols have been shown to suppress activation of transcription factors, including NF-kB and STAT3. Furthermore, polyphenols have pro-oxidant properties, with increasing evidence that polyphenols inhibit the antioxidant activity of glutathione, causing oxidative DNA damage. Polyphenols also induce autophagy-driven cancer cell death and regulate multidrug resistance proteins, and thus may be able to reverse resistance to chemotherapy agents. This review examines the molecular mechanism of action of polyphenols and discusses their potential therapeutic targets. Here, we discuss the pharmacological properties of polyphenols, including their anti-inflammatory, antioxidant, anti-proliferative, and anti-tumour activities, and suggest that polyphenols are potent natural agents that can be useful therapeutically; and discuss why data on bioavailability, toxicity and metabolism are essential to evaluate their clinical use.

The Effect of Hispidulin, a Flavonoid from Salvia plebeia, on Human Nasopharyngeal Carcinoma CNE-2Z Cell Proliferation, Migration, Invasion, and Apoptosis

Nasopharyngeal carcinoma (NPC) is a common malignant head and neck tumor. Drug resistance and distant metastasis are the predominant cause of treatment failure in NPC patients. Hispidulin is a flavonoid extracted from the bioassay-guided separation of the EtOH extract of Salvia plebeia with strong anti-proliferative activity in nasopharyngeal carcinoma cells (CNE-2Z). In this study, the effects of hispidulin on proliferation, invasion, migration, and apoptosis were investigated in CNE-2Z cells. The [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (MTT) assay and the colony formation assay revealed that hispidulin could inhibit CNE-2Z cell proliferation. Hispidulin (25, 50, 100 μM) also induced apoptosis in a dose-dependent manner in CNE-2Z cells. The expression of Akt was reduced, and the expression of the ratio of Bax/Bcl-2 was increased. In addition, scratch wound and transwell assays proved that hispidulin (6.25, 12.5, 25 μM) could inhibited the migration and invasion in CNE-2Z cells. The expressions of HIF-1α, MMP-9, and MMP-2 were decreased, while the MMPs inhibitor TIMP1 was enhanced by hispidulin. Moreover, hispidulin exhibited potent suppression tumor growth and low toxicity in CNE-2Z cancer-bearing mice at a dosage of 20 mg/kg/day. Thus, hispidulin appears to be a potentially effective agent for NPC treatment.

The Role of KDM2B and EZH2 in Regulating the Stemness in Colorectal Cancer Through the PI3K/AKT Pathway

Background: The incidence of colorectal cancer (CRC) has been increasing worldwide in recent years. Targeting cancer stem cells (CSCs) in CRC remains a difficult challenge. KDM2B and EZH2 play important role in the maintenance of CSCs' self-renewal capacity and tumorigenic ability; however, the biological functions of those genes in CRC remain unclear. In this study, we aimed to define the contribution of the expression of KDM2B in the features of CRC and establish the relationship between KDM2B and EZH2 in colorectal CSCs.

Methods: The expression of KDM2B and EZH2 in the specimens of CRC and CRC cell lines were analyzed by immunohistochemistry, Western blot, and immunofluorescence. The underlying mechanisms of altered expressions of KDM2B and EZH2 and their impact on the biologic features of CRC and stemness in CRC were investigated.

Results: The KDM2B gene was highly expressed in CRC tissues, and its overexpression positively correlated with tumor stages and tumor/node/metastasis (TNM) classification. The downregulation of KDM2B retarded cell proliferation, induced DNA damage, reduced spheroid formation, and decreased CRC stem cell markers: CD44, CD133, and ALDH-1. Moreover, the downregulation of KDM2B decreased the expression of EZH2 and both regulated cell migration, invasion, and stemness in the CRC cell line. Additionally, the interaction between KDM2B and EZH2 significantly increased the components of the PI3K/AKT pathway including AKT and PI3K. The high expression of KDM2B positively correlated with EZH2 in CRC tissues.

Conclusion: This study shows that the downregulation of KDM2B and EZH2 can regulate CRC cell stemness, and their interaction may serve as a novel prognostic marker and therapeutic target for patients with CRC.

A Newly Characterized Potentially Probiotic Strain, Lactobacillus brevis MK05, and the Toxicity Effects of its Secretory Proteins Against MCF-7 Breast Cancer Cells

Among seven strains of lactic acid bacteria (LAB) isolated from traditional dairy products, a Lactobacillus strain was identified through 16S rRNA gene sequencing and tentatively designated as Lactobacillus brevis MK05. This strain demonstrated the highest probiotic potential through biochemical analysis, including acid and bile salt resistance, as well as antibacterial activity. The collected cell-free supernatant (CFC) of L. brevis MK05 culture, compared with MRS broth with pH equal to the pH for CFC, revealed antimicrobial activity against Escherichia coli (ATCC 25922) and Staphylococcus aureus subsp. aureus (ATCC 25923), possibly due to the presence of antibacterial metabolites other than organic acids. This strain was, therefore, selected to assess the biological activity of its partially purified secretory proteins against MCF-7 cancer cells and normal fibroblast cells via the MTT assay. The partially purified cell-secreted proteins of this strain (hereafter referred to as Lb-PPSPs) showed a time and dose-dependent anti-cancer and apoptosis induction function. There was a remarkable decline in the survival rate of MCF-7 cells at doses equal to and higher than 0.5 mg/mL after 48 h. The changes in expression of the three genes involved in the apoptosis pathway (BAX, BCL-2, and BCL2L11) in MCF-7 cells treated with the Lb-PPSPs confirm its cytotoxic activity and apoptosis induction.

Enoxacin Exerts Anti-Tumor Effects Against Prostate Cancer Through Inducing Apoptosis

Background:

Prostate cancer is the most commonly diagnosed cancer and second leading cause of cancer death in men. Enoxacin, a third-generation fluoroquinolone antibiotic, was found with anti-proliferative effects against many cancer types. This study was to further investigate its effects against prostate cancer and explore the underlying molecular mechanisms.

Methods:

PC-3 cells were treated with Enoxacin at different concentrations. Tumor model was established by subcutaneously injecting PC-3 cells into nude mice. MTT assay was used to detect cell viability. ELISA assay, Annexin V/PI staining and TUNEL assay were used to detect apoptosis. RT-qPCR and western blot were used to detect the gene and protein expression, respectively.

Results:

Our data showed that Enoxacin inhibited PC-3 cell proliferation and induced the apoptosis through up-regulating the expression of pro-apoptotic proteins, while down-regulating expression levels of anti-apoptotic proteins. Moreover, Enoxacin increased the gene and protein expression of the autophagy and endoplasmic reticulum stress markers. Treating tumor-bearing mice with Enoxacin significantly inhibited tumor growth in xenograft tumor model.

Conclusion:

Our results suggested that Enoxacin could be developed as a potential anti-tumor agent against prostate carcinoma.

Anticancer activity of flavonoids accompanied by redox state modulation and the potential for a chemotherapeutic strategy

Since researchers began studying the mechanism of flavonoids' anticancer activity, little attention has been focused on the modulation of redox state in cells as a potential chemotherapeutic strategy. However, recent studies have begun identifying that the anticancer effect of flavonoids occurs both in their antioxidative activity which scavenges ROS and their prooxidative activity which generates ROS. Against this backdrop, this study attempts to achieve a comprehensive analysis of the individual and separate study findings regarding flavonoids' modulation of redox state in cancer cells. It focuses on the mechanism behind the anticancer effect, and mostly on the modulation of redox potential by flavonoids such as quercetin, hesperetin, apigenin, genistein, epigallocatechin-3-gallate (EGCG), luteolin and kaempferol in both in vitro and animal models. In addition, the clinical applications of and bioavailability of flavonoids were reviewed to help build a treatment strategy based on flavonoids' prooxidative potential.

Silencing of UAP1L1 inhibits proliferation and induces apoptosis in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is recognized as one of the malignant tumors with poor prognosis. UAP1L1 (UDP-N-acetylglucosamine-1-like-1) affects numerous biological processes, which is a key regulator of the development of malignant tumors. The biological function and molecular mechanism of UAP1L1 in ESCC were explored in this study. The relationship between UAP1L1 and ESCC was analyzed by immunohistochemical staining, revealing the high expression of UAP1L1 in ESCC. Importantly, the increased expression of UAP1L1 indicated the deterioration of patients' condition, which has clinical significance. Furthermore, the loss-of-function assays demonstrated that knockdown of UAP1L1 inhibited the progression of ESCC on suppressing proliferation, hindering migration, and enhancing apoptosis in vitro. Moreover, the apoptosis of ESCC cells was induced by knockdown of UAP1L1 via regulating a variety of apoptosis-related proteins, such as upregulation of Bax, CD40, CD40L, Fas, FasL, IGFBP-6, p21, p27, p53, and SMAC. Additionally, further investigation indicated that UAP1L1 by affecting the PI3K/Akt, CCND1, and MAPK promotes the progression of ESCC. In vivo xenograft model further confirmed that knockdown of UAP1L1 inhibited the development of ESCC. In conclusion, UAP1L1 was involved in the development and progression of ESCC, which may provide a powerful target for future molecular therapies.

Aloperine Inhibits Proliferation and Promotes Apoptosis in Colorectal Cancer Cells by Regulating the circNSUN2/miR-296-5p/STAT3 Pathway

Background

Aloperine can regulate miR-296-5p/Signal Transducer and Activator of Transcription 3 (STAT3) pathway to inhibit the malignant development of colorectal cancer (CRC), but the regulatory mechanism is unclear. This study explored the upstream mechanism of Aloperine in reducing CRC damage from the perspective of the circRNA-miRNA-mRNA regulatory network.

Methods

After treatment with gradient concentrations of Aloperine (0.1 mmol/L, 0.2 mmol/L, 0.4 mmol/L, 0.8 mmol/L and 1 mmol/L) for 24 hours, changes in CRC cell proliferation and apoptosis were detected by functional experiments. Data of the differential expression of miR-296-5p in CRC patients and healthy people were obtained from Starbase. The effects of Aloperine on 12 differentially expressed circRNAs were detected. The binding of miR-296-5p with NOP2/Sun RNA methyltransferase 2 (circNSUN2) and STAT3 was predicted by TargetScan and confirmed through dual-luciferase experiments. The expressions of circNSUN2, miR-296-5p and STAT3 as well as apoptosis-related genes in CRC cells were detected by qRT-PCR and Western blot as needed. Rescue experiments were conducted to test the regulatory effects of circNSUN2, miR-296-5p and STAT3 on CRC cells.

Results

Aloperine at a concentration gradient inhibited proliferation and promoted apoptosis in CRC cells. The abnormally low expression of miR-296-5p in CRC could be upregulated by Aloperine. Among the differentially expressed circRNAs in CRC, only circNSUN2 not only targets miR-296-5p, but also can be regulated by Aloperine. The up-regulation of circNSUN2 offset the inhibitory effect of Aloperine on cancer cells. The rescue experiments finally confirmed the regulation of circNSUN2/miR-296-5p/STAT3 axis in CRC cells.

Conclusion

By regulating the circNSUN2/miR-296-5p/STAT3 pathway, Aloperine prevents the malignant development of CRC cells.

Resveratrol Mediates the Apoptosis of Triple Negative Breast Cancer Cells by Reducing POLD1 Expression

Resveratrol (RSV) is known to possess anticancer properties in many types of cancers like breast cancer, in which POLD1 may serve as a potential target. However, the anticancer mechanism of RSV on triple negative breast cancer (TNBC) remains unclear. In the present study, the antitumor effects and mechanism of RSV on TNBC cells were analyzed by RNA sequencing (RNA-seq), which was then verified via cell counting kit-8 (CCK8), immunofluorescence, immunohistochemistry, Western Blot (WB), flow cytometry, and hematoxylin-eosin (HE) staining. According to the corresponding findings, the survival rate of MDA-MB-231 cells gradually decreased as RSV treatment concentration increased. The RNA-seq analysis results demonstrated that genes affected by RSV treatment were mainly involved in apoptosis and the p53 signaling pathway. Moreover, apoptosis of MDA-MB-231 cells induced by RSV was observed to be mainly mediated by POLD1. When treated with RSV, the expression levels of full length PARP1, PCNA, and BCL-2 were found to be significantly reduced, and the expression level of Cleaved-PARP1 as well as Cleaved-Caspase3 increased significantly. Additionally, the mRNA expression of POLD1 was significantly reduced after treatment with RSV, and the protein expression level was also inhibited by RSV in a concentration-dependent manner. The prediction of domain interaction suggested that RSV may bind to at least five functional domains of the POLD1 protein (6s1m, 6s1n, 6s1o, 6tny and 6tnz). Furthermore, after RSV treatment, the anti-apoptotic index (PCNA, BCL-2) of MDA-MB-231 cells was found to decrease while the apoptosis index (caspase3) increased. Moreover, the overexpression of POLD1 reduced the extent of apoptosis observed in MDA-MB-231 cells following RSV treatment. Moreover, animal experimental results showed that RSV had a significant inhibitory effect on the growth of live tumors, while POLD1 overexpression was shown to antagonize this inhibitory effect. Accordingly, this study’s findings reveal that RSV may promote the apoptosis of TNBC cells by reducing the expression of POLD1 to activate the apoptotic pathway, which may serve as a potential therapy for the treatment of TNBC.

Apoptosis (programmed cell death) and its signals - A review

Apoptosis is a sequential order of cell death occurring regularly to ensure a homeostatic balance between the rate of cell formation and cell death. However, a misplaced of this balancing function can contribute to an abnormal cell growth / proliferation or autoimmune disorders etc. Apoptosis is therefore said to be crucial from the point of development of an embryo throughout the growth of an organism contributing to the renewal of tissues and also the getting rid of inflammatory cells. This review seeks to elaborate on the recent overview of the mechanism involved in apoptosis, some element and signal contributing to its function and inhibition together with how their malfunction contribute to a number of cancer related cases.

Signaling, metabolism, and cancer: An important relationship for therapeutic intervention

In cancerous cells, significant changes occur in the activity of signaling pathways affecting a wide range of cellular activities ranging from growth and proliferation to apoptosis, invasiveness, and metastasis. Extensive changes also happen with respect to the metabolism of a cancerous cell encompassing a wide range of functions that include: nutrient acquisition, biosynthesis of macromolecules, and energy generation. These changes are important and some therapeutic approaches for treating cancers have focused on targeting the metabolism of cancerous cells. Oncogenes and tumor suppressor genes have a significant effect on the metabolism of cells. There appears to be a close interaction between metabolism and the signaling pathways in a cancerous cell, in which the interaction provides the metabolic needs of a cancerous cell for uncontrolled proliferation, resistance to apoptosis, and metastasis. In this review, we have reviewed the latest findings in this regard and briefly review the most recent research findings regarding targeting the metabolism of cancer cells as a therapeutic approach for treatment of cancer.

Ursolic acid induces apoptosis and anoikis in colorectal carcinoma RKO cells

BACKGROUND

Ursolic acid (UA) is an anti-cancer herbal compound. In the present study, we observed the effects of UA on anchorage-dependent and -independent growth of human colorectal cancer (CRC) RKO cells.

METHODS

RKO cells were cultured in conventional and detached condition and treated with UA. Cell viability was evaluated by CCK-8 assay. Cell cycle was analyzed by flow cytometry. Apoptosis was identified by Hoechst 33258 staining and flow cytometry analysis. Activities of caspases were measured by commercial kits. Reactive oxygen species (ROS) was recognized by DCFH-DA fluorescent staining. Anoikis was identified by EthD-1 fluorescent staining and flow cytometry analysis. Expression and phosphorylation of proteins were analyzed by western blot.

RESULTS

UA inhibited RKO cell viability in both a dose- and time-dependent manner. UA arrested the cell cycle at the G0/G1 phase, and induced caspase-dependent apoptosis. UA inhibited Bcl-2 expression and increased Bax expression. In addition, UA up-regulated the level of ROS that contributed to UA activated caspase-3, - 8 and - 9, and induced apoptosis. Furthermore, UA inhibited cell growth in a detached condition and induced anoikis in RKO cells that was accompanied by dampened phosphorylation of FAK, PI3K and AKT. UA also inhibited epithelial-mesenchymal transition (EMT) as indicated by the down-regulation of N-Cad expression and up-regulation of E-Cad expression.

CONCLUSIONS

UA induced caspase-dependent apoptosis, and FAK/PI3K/AKT singling and EMT related anoikis in RKO cells. UA was an effective anti-cancer compound against both anchorage-dependent and -independent growth of RKO cells.

Tectorigenin regulates migration, invasion, and apoptosis in dexamethasone-induced human airway epithelial cells through up-regulating miR-222-3p

Glucocorticoids (GCs) can effectively control airway inflammation, but can also cause airway epithelial injury. Tectorigenin, a type of isoflavone isolated from various medicinal plants, has hypolipidemic activity, hepatoprotective, and antioxidant effects. We aimed to investigate whether Tectorigenin can repair GCs-induced airway epithelial injury. Airway epithelial cell line (9HTE cells) were treated with dexamethasone (Dex), Tectorigenin, or further transfected, then cell viability, migration, and invasion were examined by Cell Counting Kit (CCK-8), wound healing, and Transwell assays. The expressions of potential miRNAs related to the effect of Tectorigenin were detected by quantitative polymerase chain reaction (qPCR). Expressions of poptosis-related proteins Bcl-2-associated protein-X (Bax), B-cell lymphoma-2 (Bcl-2), Cleaved Caspase-3, and related to Mitorgen-activated protein kinase (MAPK) signaling pathway serine/threonine kinase (Raf1), extracellular signal-regulated kinase kinase 1/2 (MEK1/2), and extracellular signal-regulated kinase 1/2 (ERK1/2) were detected by Western blot. Dex inhibited the cell viability, migration and invasion by promoting Bax and Cleaved Caspase-3 expressions (p <.001) and by inhibiting the expressions of Bcl-2 and miR-222-3p (p <.001). Then, 10 μmol/L Tectorigenin itself did not affect cell viability but could inhibit the effect of Dex on cell viability, migration, and invasion. Tectorigenin up-regulated the expressions of miR-222-3p, Bcl-2, p-Raf1, p-MEK1/2, and p-ERK1/2 (p <.01), but down-regulated the expressions of Bax and Cleaved Caspase-3 (p <.05) in Dex-induced cells. MiR-222-3p inhibitor reversed the antagonistic effect of Tectorigenin on Dex. The study demonstrates that Tectorigenin inhibits apoptosis of Dex-induced 9HTE cells by up-regulating the expression of miR-222-3p, which involves with the MAPK pathway.

Gracillin Isolated from Reineckia carnea Induces Apoptosis of A549 Cells via the Mitochondrial Pathway

Background

Reineckia carnea is commonly used to treat cough, pneumonia and other diseases in China. In our previous study, it was found that the ethanol extracts of Reineckia carnea have a strong inhibitory effect on the proliferation of human lung cancer A549 cells. Here, we isolated gracillin from ethanol extracts for the first time.

Purpose

Clarify the antiproliferation effect of gracillin on A549 cells and further explore its mechanisms via the mitochondrial pathway.

Methods

Gracillin was isolated and purified by silica gel, D-101 macroporous resin and preparative RP-HPLC, then identified by NMR and HR-MS. The inhibitory effects of gracillin on the proliferation of A549 cells were detected by the MTS method. Its mechanisms were further explored by flow cytometry and Western blot.

Results

A steroid saponin, gracillin, was isolated and identified from Reineckia carnea for the first time. In a concentration-dependent and time-dependent manner, gracillin significantly inhibited the proliferation of A549 cells with an IC₅₀ value at 2.54 μmol/L and induced morphological changes. The results of flow cytometry analysis showed that the apoptosis rate of A549 cells was significantly increased (p < 0.05), and the cells proportion was obviously arrested in S phase. The concentration of intracellular calcium was raised (p < 0.01), and the mitochondrial membrane potential was greatly decreased (p < 0.01). In addition, the expression levels of Bax, caspase-3, cleaved caspase-3, and cytochrome C were dramatically up-regulated while Bcl-2 was down-regulated (p < 0.05) in A549 cells.

Conclusion

This study confirmed that gracillin has a significant antiproliferative effect on A549 cells. Gracillin could induce the apoptosis of A549 cells through the mitochondrial pathway, which might be associated with regulation of the concentration of intracellular calcium, the mitochondrial membrane potential and the expression levels of Bax, Bcl-2, caspase-3, cleaved caspase-3, and cytochrome C.

Antitumor effect and molecular mechanism of fucoidan in NSCLC

Background

Fucoidan, a water-soluble polysaccharide, exerts anticoagulant and antiviral functions. It was recently reported that fucoidan also exerts an antitumor function. Lung cancer is one of the most common cancers in the world. The aim of this study was to investigate anti-tumor,apoptosis and anti-metastasis effects of fucoidan in both cell-based assays and mouse xenograft model, as well as to clarify possible role of m-TOR pathway in the protection.

Methods

In vitro: Different concentrations of fucoidan were given to act on non-small cell lung cancer (NSCLC) cell lines A549 and H1650. The effects of fucoidan on cell proliferation were observed by detecting cyclin expression levels, CCK8 and EDU experiments and cloning experiments. The apoptotic level was detected by flow cytometry and the apoptotic protein level was detected by Westernblot. By detecting the expression of adhesion molecules, the expression of matrix metalloproteinase (MMP) family, and Transwell cell invasion and migration experiment, the effect of fucoidan on cell adhesion, invasion and migration was observed. Meanwhile the effect of fucoidan on angiogenesis was observed by detecting the expression of vascular endothelial growth factor (VEGF).

In vivo experiment: An animal model of NSCLC cell mouse subcutaneous xenograft tumor was established to analyze the correlation between the consumption of fucoidan and the size and volume of xenograft tumor through gross observation. Through immunohistochemical staining and immunofluorescence double staining, ki67 and cell adhesion molecules (E-cadherin, N-cadherin and CD31) and VEGF-A in the tumor were detected, and the correlation between the amount of fucoidan and the above indexes was analyzed.

Results

Fucoidan inhibited the proliferation and angiogenesis of NSCLC cells via the mTOR pathway and promoted their apoptosis by increasing the Bax/Bcl-2 ratio. Not only that, fucoidan inhibited NSCLC cell invasion via epithelial–mesenchymal transformation (EMT). The mice fed fucoidan exhibited significant reductions in tumor volumes and weights. These indicators (Ki67, VEGF-A,N-cadherin) were decreased and E-cadherin expression was up-regulated in A549 mice that treated with fucoidan. The results showed that fucoidan inhibited tumor proliferation in vivo by affecting the expression of related proteins.

Conclusion

Fucoidan conveys antitumor effects and our results represent an ideal therapeutic agent for NSCLC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-020-03191-0.

Circular RNAs as biomarkers and therapeutic targets in cancer

Circular RNAs (circRNAs) are a class of single-stranded closed non-coding RNA molecules (ncRNAs), which are formed as a result of reverse splicing of mRNAs. Despite their relative abundance, an interest in understanding their regulatory importance is rather recent. High stability, abundance and evolutionary conservation among species underline some of their important traits. CircRNAs perform a variety of cellular functions ranging from miRNA and proteins sponges to transcriptional modulation and splicing. Additionally, most circRNAs are expressed aberrantly in pathological conditions suggesting their possible exploitation as diagnostic biomarkers. Their covalent closed cyclic structure resulting in resistance to RNases further makes them suitable as cancer biomarkers. Studies involving human tumors have verified differences in the expression profiles of circRNAs, indicating a regulatory role in cancer pathogenesis and metastasis. As endogenous competitive RNA, circRNAs can regulate tumor proliferation and invasion. Further, some circRNAs located in the nucleus can regulate transcription of genes by binding to RNA polymerase II. In this review, we elaborate the characteristics, functions and mechanisms of action of circRNAs in cancer. We also discuss the possibility of using circRNAs as potential therapeutic targets and biomarkers for cancer.

LncRNA NEAT1/miR-204/NUAK1 Axis is a Potential Therapeutic Target for Non-Small Cell Lung Cancer

Background

Long non-coding RNA (lncRNA) is a key part of non-coding RNA, and more and more evidence has revealed that it plays a vital role in tumors. NEAT1 is a lncRNA discovered in the early stage. However, it is still unclear whether NEAT1 and miR-204 play a regulatory role in lung cancer (LC). This research aimed to determine the biological function of NEAT1/miR-204 in non-small cell lung cancer (NSCLC).

Materials and Methods

In order to research the function of NEAT1 in NSCLC, RT-PCR, Western blot, luciferase assay and RNA immunoprecipitation assay were used to determine the relationship between NEAT1, miR-204 and NUAK1. CCK8 test, cell migration and invasion test were used to explore the influence of NEAT1 on proliferation and metastasis of LC cells. Tumor allotransplantation was used to detect the influence of NEAT1 on the growth of LC.

Results

The results revealed that NEAT1 was obviously enhanced in LC cell lines. Further functional analysis showed that low expression of NEAT1 obviously suppressed the growth, migration and invasion of NSCLC and facilitated cell apoptosis. Determination of luciferase reporter gene revealed that miR-204 was the direct target of NEAT1 in LC. In addition, NUAK1 was called the direct target of miR-204, and miR-204/NUAK1 had saved the role of NEAT1 in NSCLC cells. Tumor allotransplantation experiments showed that knocking down NEAT1 could inhibit the growth of LC.

Conclusion

In summary, our results showed that the down-regulation of NEAT1 in NSCLC inhibited its growth, migration and invasion through the miR-204/NUAK1 axis.

Gambogic Acid as a Candidate for Cancer Therapy: A Review

Gambogic acid (GA), a kind of dry resin secreted by the Garcinia hanburyi tree, is a natural active ingredient with various biological activities, such as anti-cancer, anti-inflammatory, antioxidant, anti-bacterial effects, etc. An increasing amount of evidence indicates that GA has obvious anti-cancer effects via various molecular mechanisms, including the induction of apoptosis, autophagy, cell cycle arrest and the inhibition of invasion, metastasis, angiogenesis. In order to improve the efficacy in cancer treatment, nanometer drug delivery systems have been employed to load GA and form micelles, nanoparticles, nanofibers, and so on. In this review, we aim to offer a summary of chemical structure and properties, anti-cancer activities, drug delivery systems and combination therapy of GA, which might provide a reference to promote the development and clinical application of GA.

Shikonin induces tumor apoptosis in glioma cells via endoplasmic reticulum stress, and Bax/Bak mediated mitochondrial outer membrane permeability

ETHNOPHARMACOLOGICAL RELEVANCE

Shikonin, one of the main active ingredients of Chinese herbal medicine Lithospermum erythrorhizon, has been widely used to treat various disease including virus infection and inflammation in clinical. Its anti-tumor activity has been recorded in "Chinese herbal medicine". Recently, some studies about its anti-glioma effects have been reported. However, little is known about the molecular pharmacological activity of Shikonin in glioma.

AIM

This study aimed to systematically uncover and validate the pharmacological mechanism of Shikonin against glioma.

MATERIAL AND METHODS

Network pharmacology approach, survival analysis, and Pearson co-expression analysis were performed to uncover and test the pharmacological mechanisms of Shikonin in glioma. Apoptosis assay, Caspase-3 activity assay and immunoblot analysis were practiced to validate the mechanisms.

RESULTS

Network pharmacology results suggested, anti-glioma effect of Shikonin by interfering endoplasmic reticulum (ER) stress-mediated tumor apoptosis targeting Caspase-3, and Bax/Bak-induced mitochondrial outer membrane permeabilization (MOMP) triggering cancer cell apoptosis. Survival analysis suggested the association of CASP3 with glioma (P < 0.05). Pearson correlation analysis indicated possible interaction of CASP3 with PERK through positive feedback regulation. Shikonin or in combination with 14G2a induced cell apoptosis in oligodendroglioma Hs683 cells in a dose-dependent manner with at a maximum apoptosis rate of 33%-37.5%, and 73%-77% respectively. Immunoblot analysis showed that Shikonin increased Caspase-3 activity to about 4.29 times, and increased 9 times when it combined with 14G2a. Shikonin increased also the expression levels of the proteins PERK and CHOP by about 4.4 and 5.6 folds, respectively, when it combined with 14G2a.

CONCLUSIONS

This study highlights the pharmacological mechanisms of Shikonin in the induction of tumor apoptosis in glioma cells.

Zinc Protects against MDMA-Induced Apoptosis of Sertoli Cells in Mouse via Attenuation of Caspase-3

Background

3,4-Methylenedioxymethamphetamine (MDMA) disrupts function of the endocrine system and different organs such as heart, blood vessels, kidney, liver and nervous systems. This revision was conducted to evaluate impact of MDMA on apoptosis and Zinc in the MDMA-induced apoptosis of cultured Sertoli cells by measuring Caspase-3 gene expression.

Materials and Methods

In this experimental study, Sertoli cells were incubated with MDMA (0, 0.5, 1, 3 and 5 mM), Zinc (0, 8, 16, 32, 64 μM) and Zinc (8 μM) prior to adding MDMA (5 mM) for 24 and 48 hours. MTT assay was used for evaluating impacts of these conditions on the viability of Sertoli cells. Caspase-3 gene expression level was detected using quantitative reverse transcription PCR (qRT-PCR) in all of the tested groups.

Results

Finding showed that cellular viability was decreased and level of Caspase-3 mRNA was increased in MDMA treated cells. Additionally, pre-treatment with Zinc (8 μM) attenuated MDMA-induced apoptosis and down-regulated caspase-3. The mean of caspase-3 mRNA level (fold change ± SE) was 3.98 ± 1.18, 0.31 ± 0.28, and 1.72 ± 0.28 in respectively MDMA (5 mM), Zinc (8 μM), and Zinc+MDMA groups vs. control group. The mean of Caspase-3 mRNA (fold change) was not statistically different in the tested groups (P>0.05), unless MDMA (5 mM) group (P=0.008).

Conclusion

We suggest that MDMA toxicity could be involved in apoptosis of Sertoli cells. In addition, Zinc could reduce MDMA-induced apoptosis by down-regulation of Caspase-3 mRNA levels.

Autophagy Takes Center Stage as a Possible Cancer Hallmark

Cancer remains one of the leading causes of death worldwide, despite significant advances in cancer research and improvements in anticancer therapies. One of the major obstacles to curing cancer is the difficulty of achieving the complete annihilation of resistant cancer cells. The resistance of cancer cells may not only be due to intrinsic factors or factors acquired during the evolution of the tumor but may also be caused by chemotherapeutic treatment failure. Conversely, autophagy is a conserved cellular process in which intracellular components, such as damaged organelles, aggregated or misfolded proteins and macromolecules, are degraded or recycled to maintain cellular homeostasis. Importantly, autophagy is an essential mechanism that plays a key role in tumor initiation and progression. Depending on the cellular context and microenvironmental conditions, autophagy acts as a double-edged sword, playing a role in inducing apoptosis or promoting cell survival. In this review, we propose several scenarios in which autophagy could contribute to cell survival or cell death. Moreover, a special focus on novel promising targets and therapeutic strategies based on autophagic resistant cells is presented.

Chemopreventive Potential of Caryophyllane Sesquiterpenes: An Overview of Preliminary Evidence

Chemoprevention is referred to as a strategy to inhibit, suppress, or reverse tumor development and progression in healthy people along with high-risk subjects and oncologic patients through using pharmacological or natural substances. Numerous phytochemicals have been widely described in the literature to possess chemopreventive properties, although their clinical usefulness remains to be defined. Among them, caryophyllane sesquiterpenes are natural compounds widely occurring in nature kingdoms, especially in plants, fungi, and marine environments. Several structures, characterized by a common caryophyllane skeleton with further rearrangements, have been identified, but those isolated from plant essential oils, including β-caryophyllene, β-caryophyllene oxide, α-humulene, and isocaryophyllene, have attracted the greatest pharmacological attention. Emerging evidence has outlined a complex polypharmacological profile of caryophyllane sesquiterpenes characterized by blocking, suppressing, chemosensitizing, and cytoprotective properties, which suggests a possible usefulness of these natural substances in cancer chemoprevention for both preventive and adjuvant purposes. In the present review, the scientific knowledge about the chemopreventive properties of caryophyllane sesquiterpenes and the mechanisms involved have been collected and discussed; moreover, possible structure-activity relationships have been highlighted. Although further high-quality studies are required, the promising preclinical findings and the safe pharmacological profile encourage further studies to define a clinical usefulness of caryophyllane sesquiterpenes in primary, secondary, or tertiary chemoprevention.

Folate-targeted PTEN/AKT/P53 signaling pathway promotes apoptosis in breast cancer cells

Objective Folate deficiency is closely related to the occurrence of human tumors and plays an important role in cell growth, differentiation, repair, and host defense. We studied the effects of folic acid on the apoptosis of breast cancer cells (MDA-MB-231) and on the activity of the PTEN/AKT/P53 signaling pathway in breast cancer cells.

Methods Breast cancer cells (MDA-MB-231) were treated with folate alone or in combination with a PTEN specific inhibitor, SF1670. Cell viability was detected by a MTT assay, and the expression levels of apoptosis-related proteins and PTEN/AKT/P53 signaling pathway were detected via Western blot analysis. Rate of apoptosis was measured via cytometry.

Results Folic acid inhibited the cell viability of MDAMB-231 cells and the expressions of Bcl-2 and p-AKT proteins and upregulate the expression of Bax, PTEN, and P53 proteins, thereby inducing apoptosis in these cells. SF1670 treatment inhibited the expressions of Bcl-2 and p-AKT protein and upregulate Bax, PTEN, and P53 protein expression.

Conclusion Folic acid has cytotoxic effects on MDAMB-231 cells and can induce apoptosis by targeting the PTEN/AKT/P53 signaling pathway.

Targeting pyroptosis to regulate ischemic stroke injury: Molecular mechanisms and preclinical evidences

Stroke is one of the leading causes of death worldwide with limited therapies. After ischemic stroke occurs, a robust sterile inflammatory response happens and lasts for days and determines neurological prognosis. Pyroptosis is an inflammatory programmed cell death characterized by cleavage of pore-forming proteins gasdermins as a result of activating caspases and inflammasomes. It has morphological characteristics of rapid plasma-membrane rupture and release of proinflammatory intracellular contents as well as cytokines. Recent researches implicate pyroptosis involvement in the pathogenesis of ischemic stroke and inhibition of pyroptosis attenuates ischemic brain injury. In this review, we discussed molecular mechanisms of pyroptosis, evidences for pyroptosis involvement in different kinds of the central nervous system cells, as well as potential inhibitors for intervention of pyroptosis. Based on the review, we hypothesize the feasibility of therapeutic strategies targeting pyroptosis in the context of ischemic stroke.

Alcohol and hepatocarcinogenesis

An excessive alcohol intake may result in fatty liver, acute/chronic hepatitis, cirrhosis, and lead to hepatocellular carcinoma (HCC). The aim of this review is to clarify the present condition and the mechanisms of alcohol-related hepatocarcinogenesis and clinical risk factors for alcohol-related HCC. There are several possible mechanisms through which alcohol may induce hepatocarcinogenesis, including the mutagenic effects of acetaldehyde toxicity through the formation of protein and DNA adducts and the production of reactive oxygen species due to the excessive hepatic deposition of iron, changes to lipid peroxidation and metabolism, inflammation and an impaired immune response and modifications to DNA methylation. Furthermore, it has been reported that alcohol accelerates liver carcinogenesis through several signaling pathways including gut-liver axis. From a clinical perspective, it is well known that alcohol interacts with other factors, such as age, gender, viral hepatitis, obesity, and diabetes leading to an increased risk of HCC.

The Intracellular Number of Magnetic Nanoparticles Modulates the Apoptotic Death Pathway after Magnetic Hyperthermia Treatment

Magnetic hyperthermia is a cancer treatment based on the exposure of magnetic nanoparticles to an alternating magnetic field in order to generate local heat. In this work, 3D cell culture models were prepared to observe the effect that a different number of internalized particles had on the mechanisms of cell death triggered upon the magnetic hyperthermia treatment. Macrophages were selected by their high capacity to uptake nanoparticles. Intracellular nanoparticle concentrations up to 7.5 pg Fe/cell were measured both by elemental analysis and magnetic characterization techniques. Cell viability after the magnetic hyperthermia treatment was decreased to <25% for intracellular iron contents above 1 pg per cell. Theoretical calculations of the intracellular thermal effects that occurred during the alternating magnetic field application indicated a very low increase in the global cell temperature. Different apoptotic routes were triggered depending on the number of internalized particles. At low intracellular magnetic nanoparticle amounts (below 1 pg Fe/cell), the intrinsic route was the main mechanism to induce apoptosis, as observed by the high Bax/Bcl-2 mRNA ratio and low caspase-8 activity. In contrast, at higher concentrations of internalized magnetic nanoparticles (1-7.5 pg Fe/cell), the extrinsic route was observed through the increased activity of caspase-8. Nevertheless, both mechanisms may coexist at intermediate iron concentrations. Knowledge on the different mechanisms of cell death triggered after the magnetic hyperthermia treatment is fundamental to understand the biological events activated by this procedure and their role in its effectiveness.

Ruthenium(II)/(III) DMSO-Based Complexes of 2-Aminophenyl Benzimidazole with In Vitro and In Vivo Anticancer Activity

New anticancer ruthenium(II/III) complexes [RuCl₂(DMSO)₂(Hapbim)] (1) and [RuCl₃(DMSO) (Hapbim)] (2) (Hapbim = 2-aminophenyl benzimidazole) have been synthesized and characterized, and their chemotherapeutic potential evaluated. The interaction of the compounds with DNA was studied by both UV-Visible and fluorescence spectroscopies, revealing intercalation of both the Hapbim ligand and the Ru complexes. The in vitro cytotoxicity of the compounds was tested on human breast cancer (MCF7), human colorectal cancer (Caco2), and normal human liver cell lines (THLE-2), with compound (2) the most potent against cancer cells. The cytotoxic effect of (2) is shown to correlate with the ability of the Ru(III) complex to induce apoptosis and to cause cell-cycle arrest in the G2/M phase. Notably, both compounds were inactive in the noncancerous cell line. The anticancer effect of (2) has also been studied in an EAC (Ehrlich Ascites Carcinoma) mouse model. Significantly, the activity of the complex was more pronounced in vivo, with removal of the cancer burden at doses that resulted in only low levels of hepatotoxicity and nephrotoxicity. An apoptosis mechanism was determined by the observation of increased Bax and caspase 3 and decreased Bcl2 expression. Furthermore, (2) decreased oxidative stress and increased the levels of antioxidant enzymes, especially SOD, suggesting the enhancement of normal cell repair. Overall, compound (2) shows great potential as a chemotherapeutic candidate, with promising activity and low levels of side effects.