Eriocalyxin B, a novel autophagy inducer, exerts anti-tumor activity through the suppression of Akt/mTOR/p70S6K signaling pathway in breast cancer

The interplay between autophagy and ferroptosis presents a novel conceptual therapeutic framework for neuroendocrine prostate cancer

In American men, the incidence of prostate cancer (PC) is the highest among all types of cancer, making it the second leading cause of mortality associated with cancer. For advanced or metastatic PC, antiandrogen therapies are standard treatment options. The administration of these treatments unfortunately carries the potential risk of inducing neuroendocrine prostate cancer (NEPC). Neuroendocrine differentiation (NED) serves as a crucial indicator of prostate cancer development, encompassing various factors such as phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR), Yes-associated protein 1 (YAP1), AMP-activated protein kinase (AMPK), miRNA. The processes of autophagy and ferroptosis (an iron-dependent form of programmed cell death) play pivotal roles in the regulation of various types of cancers. Clinical trials and preclinical investigations have been conducted on many signaling pathways during the development of NEPC, with the deepening of research, autophagy and ferroptosis appear to be the potential target for regulating NEPC. Due to the dual nature of autophagy and ferroptosis in cancer, gaining a deeper understanding of the developmental programs associated with achieving autophagy and ferroptosis may enhance risk stratification and treatment efficacy for patients with NEPC.

Mechanisms of Traditional Chinese medicine/natural medicine in HR-positive Breast Cancer: A comprehensive Literature Review

ETHNOPHARMACOLOGICAL RELEVANCE

With the emergence of endocrine resistance, the survival and good prognosis of HR-positive breast cancer (HR + BC) patients are threatened. As a common complementary and alternative therapy in cancer treatment, traditional Chinese medicine (TCM) has been widely used, and its internal mechanisms have been increasingly explored.

AIM OF THE REVIEW

In this review, the development status and achievements in understanding of the mechanisms related to the anti-invasion and anti-metastasis effects of TCM against HR + BC and the reversal of endocrine drug resistance by TCM in recent years have been summarized to provide ideas for antitumour research on the active components of TCM/natural medicine.

METHODS

We searched the electronic databases PubMed, Web of Science, and China National Knowledge Infrastructure database (CNKI) (from inception to July 2023) with the key words "HR-positive breast cancer" or "HR-positive breast carcinoma", "HR + BC" and "traditional Chinese medicine", "TCM", or "natural plant", "herb", etc., with the aim of elucidating the intrinsic mechanisms of traditional Chinese medicine and natural medicine in the treatment of HR + BC.

RESULTS

TCM/natural medicine monomers and formulas can regulate the expression of related genes and proteins through the PI3K/AKT, JAK2/STAT3, MAPK, Wnt and other signalling pathways, inhibit the proliferation and metastasis of HR + BC tumours, play a synergistic role in combination with endocrine drugs, and reverse endocrine drug resistance.

CONCLUSION

The wide variety of TCM/natural medicine components makes the research and development of new methods of TCM for BC treatments more selective and innovative. Although progress has been made on research on TCM/natural medicine, there are still many problems in clinical and basic experimental designs, and more in-depth scientific explorations and research are still needed.

Natural Activators of Autophagy

Autophagy is the process by which cell contents, such as aggregated proteins, dysfunctional organelles, and cell structures are sequestered by autophagosome and delivered to lysosomes for degradation. As a process that allows the cell to get rid of non-functional components that tend to accumulate with age, autophagy has been associated with many human diseases. In this regard, the search for autophagy activators and the study of their mechanism of action is an important task for treatment of many diseases, as well as for increasing healthy life expectancy. Plants are rich sources of autophagy activators, containing large amounts of polyphenolic compounds in their composition, which can be autophagy activators in their original form, or can be metabolized by the intestinal microbiota to active compounds. This review is devoted to the plant-based autophagy activators with emphasis on the sources of their production, mechanism of action, and application in various diseases. The review also describes companies commercializing natural autophagy activators.

Natural product Eriocalyxin B suppressed triple negative breast cancer metastasis both in vitro and in vivo

Breast cancer is the most commonly diagnosed cancer among women, and its metastasis to distant organs accounts for the majority of death. Eriocalyxin B (Eri B), an ent-kaurane diterpenoid isolating from Isodon eriocalyx var. laxiflora, has previously been reported to have anti-tumor and anti-angiogenic effects in breast cancer. Here, we investigated the effect of Eri B on cell migration and adhesion in triple negative breast cancer (TNBC) cells, as well as aldehyde dehydrogenases 1 family member A1 (ALDH1A1) expression, colony- and sphere-formation in cancer stem cell (CSC) enriched MDA-MB-231 cells. The in vivo anti-metastatic activities of Eri B were determined in 3 different breast tumor-bearing mouse models. Our results indicated that Eri B inhibited TNBC cell migration and adhesion to extracellular matrix proteins, and also reduced ALDH1A1 expression and colony formation in CSC-enriched MDA-MB-231 cells. The metastasis-related pathways, such as epidermal growth factor receptor/ mitogen-activated protein kinase kinases 1/2/ extracellular regulated protein kinase signaling altered by Eri B was firstly shown in MDA-MB-231 cells. The potent anti-metastatic efficacies of Eri B were demonstrated in breast xenograft-bearing mice and syngeneic breast tumor-bearing mice. Gut microbiome analysis results revealed the change in the diversity and composition of microbiome after Eri B treatment, and the potential pathways that are involved in the anti-cancer efficacy of Eri B. In conclusion, Eri B was shown to inhibit breast cancer metastasis in both in vitro and in vivo models. Our findings further support the development of Eri B as an anti-metastatic agent for breast cancer.

Compounds from diverse natural origin against triple-negative breast cancer: A comprehensive review

Triple-negative breast cancer (TNBC) is caused due to the lack of estrogen receptors (ER), progesterone receptors (PR), and human epidermal growth factor 2 (HER2) expression. Triple-negative breast cancer is the most aggressive heterogeneous disease that is capable of producing different clones and mutations. Tumorigenesis in TNBC is caused due to the mutation or overexpression of tumor suppressor genes. It is also associated with mutations in the BRCA gene which is linked to hereditary breast cancer. In addition, PARP proteins and checkpoint proteins also play a crucial function in causing TNBC. Many cell signaling pathways are dysregulated in TNBC. Even though chemotherapy and immunotherapy are good options for TNBC treatment, the response rates are still low in general. Many phytochemicals that are derived from natural compounds have shown very good inhibitions for TNBC. Natural compounds have the great advantage of being less toxic, having lesser side effects, and being easily available. The secondary metabolites such as alkaloids, terpenoids, steroids, and flavonoids in natural products make them promising inhibitors of TNBC. Their compositions also offer vital insights into inhibitory action, which could lead to new cancer-fighting strategies. This review can help in understanding how naturally occurring substances and medicinal herbs decrease specific tumors and pave the way for the development of novel and extremely efficient antitumor therapies.

A vicious circle in breast cancer: The interplay between inflammation, reactive oxygen species, and microRNAs

Breast cancer (BC) is the most common cancer in women worldwide. This highly heterogeneous disease is molecularly stratified into luminal A, luminal B, HER2, triple-negative/basal-like, and normal-like subtypes. An important aspect in BC progression is the activation of inflammatory processes. The activation of CD8+/Th1, NK, and M1 tumor associated macrophages (TAMs), leads to tumor destruction. In contrast, an anti-inflammatory response mediated by CD4+/Th2 and M2 TAMs will favor tumor progression. Inflammation also stimulates the production of inflammatory mediators like reactive oxygen species (ROS). In chronic inflammation, ROS activates oxidative stress and endothelial dysfunction. In cancer, ROS plays a dual role with anti-tumorigenic and pro-tumorigenic effects in cell signaling pathways that control proliferation, survival, apoptosis, and inflammation. MicroRNAs (miRNAs), which are known to be involved in BC progression and inflammation, can be regulated by ROS. At the same time, miRNAs regulate the expression of genes modulating oxidative stress. In this review, we will discuss the interplay between inflammation, ROS, and miRNAs as anticancer and tumor promoter molecules in BC. A clear understanding of the role of miRNAs in the regulation of ROS production and inflammation, may lead to new opportunities for therapy in BC.

Natural diterpenoid eriocalyxin B covalently modifies glutathione and selectively inhibits thioredoxin reductase inducing potent oxidative stress-mediated apoptosis in colorectal carcinoma RKO cells

Increasing evidence suggests the significant contribution of high levels of thioredoxin reductase (TrxR) in various stages of tumorigenesis and resistance to tumor chemotherapy. Thus, inhibition of TrxR with small molecules is an attractive strategy for cancer therapy. Eriocalyxin B (EriB), a naturally occurring diterpenoid extracted from Isodon eriocalyx, has reflected potential anticancer activities through numerous pathways. Here, we describe that EriB covalently modifies GSH and selectively inhibits TrxR activity by targeting the Sec residue of the enzyme. Pharmacological inhibition of TrxR by EriB results in elevated ROS levels, reduced total GSH and thiols content, which ultimately induced potent RKO cell apoptosis mediated by oxidative stress. Importantly, EriB indicates potent synthetic lethality with GSH inhibitors, BSO, in RKO cells. In summary, our results highlight that targeting TrxR by EriB explores a novel mechanism for the biological action of EriB. This opened up a new therapeutic indication for using EriB to combat cancers.

Repurposing drugs as novel triple negative breast cancer therapeutics

BACKGROUND

Among all the types of breast cancer (BC), triple negative breast cancer (TNBC) is the most aggressive form having high metastasis and recurrence rate with limited treatment options. Conventional treatments such as chemotherapy and radiotherapy have lots of toxic side effects and also no FDA approved therapies are available till now. Repurposing of old clinically approved drugs towards various targets of TNBC is the new approach with lesser side effects and also leads to successful inexpensive drug development with less time consuming. Medicinal plants containg various phytoconstituents (flavonoids, alkaloids, phenols, essential oils, tanins, glycosides, lactones) plays very crucial role in combating various types of diseases and used in drug development process because of having lesser side effects.

OBJECTIVE

The present review focuses in summarization of various categories of repurposed drugs against multitarget of TNBC and also summarizes the phytochemical categories that targets TNBC singly or in combination with synthetic old drugs.

METHODS

Literature information was collected from various databases such as Pubmed, Web of Science, Scopus and Medline to understand and clarify the role and mechanism of repurposed synthetic drugs and phytoconstituents aginst TNBC by using keywords like "breast cancer", "repurposed drugs", "TNBC" and "phytoconstituents".

RESULTS

Various repurposed drugs and phytochemicals targeting different signaling pathways that exerts their cytotoxic activities on TNBC cells ultimately leads to apoptosis of cells and also lowers the recurrence rate and stops the metastasis process.

CONCLUSION

Inhibitory effects seen in different levels, which provides information and evidences to researchers towards drug developments process and thus further more investigations and researches need to be taken to get the better therapeutic treatment options against TNBC.

Genistein Inhibits Colonic Goblet Cell Loss and Colorectal Inflammation Induced by Salmonella Typhimurium Infection

SCOPE

Salmonella is the main food-borne pathogen, which can infect intestinal epithelial cells and causes colitis. Genistein has a variety of biological activities that alleviates colitis induced by sodium dextran sulfate in a variety of ways, but its protective effects on colitis caused by pathogenic bacteria are still unknown.

METHODS AND RESULTS

This study explores the protective effect of genistein in reducing colitis caused by Salmonella infection. Salmonella causes colon inflammation through activating cyclooxygenase-2/prostaglandin E2, and genistein inhibits colitis caused by Salmonella typhimurium infection. Salmonella infection increases colonic mucosal damage, proliferating cells, and goblet cell loss, while the administration of genistein solves these pathological changes. In addition, it is further proved that Salmonella causes severe colitis related to goblet cell loss and activates the host crypt stem cells to repair the damaged epithelium. Salmonella infection inhibites the host mammalian target of rapamycin, activates light chain 3 II pathways to induce autophagy to eliminate pathogenic bacteria. Genistein increases Lactobacillus in feces and reduces Salmonella colonization to inhibit colitis induces by Salmonella infection.

CONCLUSION

This study demonstrates genistein alleviated colitis and inhibites the goblet cell loss causes by Salmonella infection through regulating the gut bacteria and intestinal stem cell development.

Autophagy Modulators in Cancer Therapy

Autophagy is a process of self-degradation that plays an important role in removing damaged proteins, organelles or cellular fragments from the cell. Under stressful conditions such as hypoxia, nutrient deficiency or chemotherapy, this process can also become the strategy for cell survival. Autophagy can be nonselective or selective in removing specific organelles, ribosomes, and protein aggregates, although the complete mechanisms that regulate aspects of selective autophagy are not fully understood. This review summarizes the most recent research into understanding the different types and mechanisms of autophagy. The relationship between apoptosis and autophagy on the level of molecular regulation of the expression of selected proteins such as p53, Bcl-2/Beclin 1, p62, Atg proteins, and caspases was discussed. Intensive studies have revealed a whole range of novel compounds with an anticancer activity that inhibit or activate regulatory pathways involved in autophagy. We focused on the presentation of compounds strongly affecting the autophagy process, with particular emphasis on those that are undergoing clinical and preclinical cancer research. Moreover, the target points, adverse effects and therapeutic schemes of autophagy inhibitors and activators are presented.

Natural products: A lead for drug discovery and development

Natural products are used since ancient times in folklore for the treatment of various ailments. Plant-derived products have been recognized for many years as a source of therapeutic agents and structural diversity. A literature survey has been carried out to determine the utility of natural molecules and their modified analogs or derivatives as pharmacological active entities. This review presents a study on the importance of natural products in terms of drug discovery and development. It describes how the natural components can be utilized after small modifications in new perspectives. Various new modifications in structure offer a unique opportunity to establish a new molecular entity with better pharmacological potential. It was concluded that in this current era, new attempts are taken to utilize the compounds derived from natural sources as novel drug candidates, with a focus to find and discover new effective molecules that were referred to as "new entities of natural product drug discovery."

Fangchinoline exerts anticancer effects on colorectal cancer by inducing autophagy via regulation AMPK/mTOR/ULK1 pathway

Autophagy has become a promising target for cancer therapy. Fangchinoline (Fan) has been shown to exert anticancer effects in some types of cancers. However, the anticancer effects on colorectal cancer (CRC) and the underlying mechanisms have never been elucidated. More specifically, regulation of autophagy in CRC by Fan has never been reported before. In the present study, Fan was found to induce apoptosis and autophagic flux in the CRC cell lines HT29 and HCT116, which was reflected by the enhanced levels of LC3-II protein and p62 degradation, and the increased formation of autophagosomes and puncta formation by LC3-II. Meanwhile, combination with the early-stage autophagy inhibitor 3-methyladenine (3-MA) but not the late-stage autophagy inhibitor chloroquine (CQ) further increased Fan-induced cell death, which suggested the cytoprotective function of autophagy induced by Fan in both HT29 and HCT116 cells. Moreover, Fan treatment demonstrated a dose- and time-dependently increase in the phosphorylation of AMPK and decrease in the phosphorylation of mammalian target of rapamycin (mTOR) and ULK1, leading to the activation of the AMPK/mTOR/ULK1 signaling pathway. Furthermore, in the HT29 xenograft model, Fan inhibited tumor growth in vivo. These results indicate that Fan inhibited CRC cell growth both in vitro and in vivo and revealed a new molecular mechanism involved in the anticancer effect of Fan on CRC, suggesting that Fan is a potent autophagy inducer and might be a promising anticancer agent.

The signaling pathways and targets of traditional Chinese medicine and natural medicine in triple-negative breast cancer

ETHNOPHARMACOLOGICAL RELEVANCE

Triple-negative breast cancer (TNBC) has a poorer prognosis than other subtypes due to its strong invasion and higher risk of distant metastasis. Traditional Chinese medicine (TCM) and natural medicine have the unique advantages of multitargets and small side-effects and may be used as long-term complementary and alternative therapies.

AIM OF THE REVIEW

The present article summarizes the classical signaling pathways and potential targets by the action of TCM and natural medicine (including extracts, active constituents and formulas) on TNBC and provides evidence for its clinical efficacy.

METHODS

The literature information was acquired from the scientific databases PubMed, Web of Science and CNKI from January 2010 to June 2020, and it was designed to elucidate the internal mechanism and role of TCM and natural medicine in the treatment of TNBC. The search key words included "Triple negative breast cancer" or "triple negative breast carcinoma", "TNBC" and "traditional Chinese medicine" or "Chinese herbal medicine", "medicinal plant", "natural plant", and "herb".

RESULTS

We described the antitumor activity of TCM and natural medicine in TNBC based on different signaling pathways. Plant medicine and herbal formulas regulated the related gene and protein expression via pathways such as PI3K/AKT/mTOR, MAPK and Wnt/β-catenin, which inhibit the growth, proliferation, migration, invasion and metastasis of TNBC cells.

CONCLUSION

The inhibitory effect of TCM and natural medicine on tumors was reflected in multiple levels and multiple pathways, providing reasonable evidence for new drug development. To make TCM and natural medicine widely and flexibly used in clinical practice, the efficacy, safety and mechanism of action need more in-depth experimental research.

YAP manipulates proliferation via PTEN/AKT/mTOR-mediated autophagy in lung adenocarcinomas

Background

Autophagy is a double-edged sword during the initiation and progression of multiple tumors. The Hippo pathway effector YAP has been proved to be involved in autophagy processes. The present study aimed to investigate how YAP regulates cell proliferation via autophagy in lung adenocarcinomas (LUAD).

Methods

Data of LUAD chip GSE43458 was obtained from Gene Expression Omnibus (GEO). RT-qPCR and Western blot were performed to assess YAP expression in LUAD cell lines. CCK-8 assay, xenograft tumor model, immunochemistry and GFP-mRFP-LC3 fusion proteins were utilized to evaluate the effect of YAP on autophagy of LUAD cells in vitro and in vivo. Autophagy inhibitor treatment and rescue experiments were carried out to elucidate the mechanism by which YAP manipulates autophagy in LUAD cells.

Results

YAP was significantly overexpressed in samples of LUAD patients and its expression level is related to 5-year survival. YAP manipulated the proliferation and autophagy in A549 and H1299 LUAD cells. YAP could induce activation of Akt/mTOR signaling pathway via suppressing PTEN in a Hippo-pathway-dependent manner. 3-Methyladenine impeded autophagy flux and promoted the proliferation in vitro and in vivo.

Conclusions

Hippo pathway critical transcriptional coactivators YAP manipulates the proliferation of lung adenocarcinoma, which is regulated by PTEN/AKT/mTOR autophagic signaling.

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field.

DNA damage response and breast cancer development: Possible therapeutic applications of ATR, ATM, PARP, BRCA1 inhibition

Breast cancer is the most common and significant cancers in females regarding the loss of life quality. Similar to other cancers, one of the etiologic factors in breast cancer is DNA damage. A plethora of molecules are responsible for sensing DNA damage and mediating actions which lead to DNA repair, senescence, cell cycle arrest and if damage is unbearable to apoptosis. In each of these, aberrations leading to unrepaired damage was resulted in uncontrolled proliferation and cancer. Another cellular function is autophagy defined as a process eliminating of unnecessary proteins in stress cases involved in pathogenesis of cancer. Knowing their role in cancer, scholars have tried to develop strategies in order to target DDR and autophagy. Further, the interactions of DDR and autophagy plus their regulatory role on each other have been focused simultaneously. The present review study has aimed to illustrate the importance of DDR and autophagy in breast cancer according to the related studies and uncover the relation between DDR and autophagy and its significance in breast cancer therapy.

Effect of Eriocalyxin B on prostatic inflammation and pelvic pain in a mouse model of experimental autoimmune prostatitis

BACKGROUND

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a common disease in males. Eriocalyxin B (EriB), a natural diterpenoid purified from Isodon eriocalyx var. laxiflora, was previously reported to have antitumor effects via multiple immune-related pathways. In this study, we investigated the effect of EriB on CP/CPPS using a mouse model of experimental autoimmune prostatitis (EAP) and explored its potential mechanisms.

METHODS

The EAP model was established in nonobese diabetic mice by intradermal injecting a mixture of prostate antigens and Complete Freund's Adjuvant on days 0 and 28. Then, EAP mice received daily intraperitoneal injections of EriB (5 or 10 mg/kg/d) for 14 days, from days 28 to 42 (EAP+EriB5 or EAP+EriB10 groups). The histopathological appearance of the prostate tissues was evaluated. Chronic pelvic pain development was assessed by cutaneous allodynia. Inflammatory cytokines were measured by enzyme-linked immunosorbent assay tests. We then explored anti-inflammatory potential mechanisms of EriB by studying the effects of PI3K inhibitor wortmannin (EAP+EriB10+Wort group) and NF-κB inhibitor SC75741 (EAP+EriB10+SC group) on prostate inflammation and pelvic pain using this model.

RESULTS

Histological analyses revealed significant prostate inflammation in EAP mice compared with control mice. Significantly increased pelvic pain was detected in EAP mice (P < .05). Compared with the EAP+Veh group, chronic pain development, histological appearance, and cytokine levels demonstrated that EriB could alleviate the severity of EAP in a dose-dependent manner though upregulation of the PI3K/Akt/mTOR pathway and downregulation of the NF-κB pathway. Further mechanism research demonstrated that the PI3K/AKT/mTOR pathway could be blocked by wortmannin, but was not affected by SC75741. In addition, the NF-κB pathway could be further inhibited by SC75741 compared with the EAP+EriB10+Veh group. However, wortmannin could reactivate the NF-κB pathway, indicating that the PI3K/AKT/mTOR pathway negatively regulates the NF-κB pathway during EriB treatment.

CONCLUSIONS

The results of the present study suggested that EriB could alleviate the severity of prostatic inflammation and pelvic pain in an EAP mouse model. These findings may broaden the value of EriB as a promising candidate for the treatment of CP/CPPS.

Eriocalyxin B Inhibits Adipogenesis in 3T3-L1 Adipocytes by Cell Cycle Arrest

Eriocalyxin B, an ent-Kaurene diterpenoid extracted from a traditional Chinese herb Isodon eriocalyx, has been shown to possess multifunctional activities such as anti-cancer and anti-inflammatory. However, the function and mechanism of the compound in adipocyte differentiation is still unknown. Here we reported that eriocalyxin B blunted adipogenesis remarkably by inhibiting the accumulation of lipid droplets, triglycerides and the expressions of adipogenesis-related factors, including C/EBPβ, C/EBPα, PPARγ, and FABP4. Moreover, we showed that the inhibition might be the consequence of cell cycle being arrested at the G2/M phase during the mitotic clonal expansion of adipocyte differentiation, most likely by suppressing mRNAs and proteins of CDK1, CDK2, Cyclin A and Cyclin B1. Overall, we conclude that eriocalyxin B is capable of inhibiting adipocyte differentiation at the early stage through downregulating the proteins involved in cell cycle progression.

Mechanistic Pathways and Molecular Targets of Plant-Derived Anticancer ent-Kaurane Diterpenes

Since the first discovery in 1961, more than 1300 ent-kaurane diterpenoids have been isolated and identified from different plant sources, mainly the genus Isodon. Chemically, they consist of a perhydrophenanthrene subunit and a cyclopentane ring. A large number of reports describe the anticancer potential and mechanism of action of ent-kaurane compounds in a series of cancer cell lines. Oridonin is one of the prime anticancer ent-kaurane diterpenoids that is currently in a phase-I clinical trial in China. In this review, we have extensively summarized the anticancer activities of ent-kaurane diterpenoids according to their plant sources, mechanistic pathways, and biological targets. Literature analysis found that anticancer effect of ent-kauranes are mainly mediated through regulation of apoptosis, cell cycle arrest, autophagy, and metastasis. Induction of apoptosis is associated with modulation of BCL-2, BAX, PARP, cytochrome c, and cleaved caspase-3, -8, and -9, while cell cycle arrest is controlled by cyclin D1, c-Myc, p21, p53, and CDK-2 and -4. The most common metastatic target proteins of ent-kauranes are MMP-2, MMP-9, VEGF, and VEGFR whereas LC-II and mTOR are key regulators to induce autophagy.

Association between obesity and breast cancer: Molecular bases and the effect of flavonoids in signaling pathways

Obesity is an abnormal or excessive accumulation of fat that leads to different health problems, such as cancer, where the adipocytes promote the proliferation, migration, and invasion of cancer cells, especially in the breast, where the epithelial cells are immersed in a fatty environment, and the interactions between these two types of cells involve, not only adipokines but also local pro-inflammatory mechanisms and hypoxic processes generating anti-apoptotic signals, which are a common result in leptin signaling. The expression of the Vascular Endothelial Growth Factor (VEGF) and cyclin D1, results in the decrease in phosphorylation of AMPK, increasing the activity of the aromatase enzyme; alternatively, the adiponectin activates AMPK to reduce inflammation. Nevertheless, alterations of the JAK/STAT pathways contribute to mammary carcinogenesis, while the PI3K/AKT/mTOR pathway controls most of the cancer's characteristics such as the cell cycle, survival, differentiation, proliferation, motility, metabolism, and genetic stability. Therefore, the purpose of the present review is, through the accumulated scientific evidence, to find the concordance between the signaling pathways involved among obesity and breast cancer, which can be modulated by using flavonoids.

Role of Reactive Oxygen Species in Cancer Progression: Molecular Mechanisms and Recent Advancements

Reactive oxygen species (ROS) play a pivotal role in biological processes and continuous ROS production in normal cells is controlled by the appropriate regulation between the silver lining of low and high ROS concentration mediated effects. Interestingly, ROS also dynamically influences the tumor microenvironment and is known to initiate cancer angiogenesis, metastasis, and survival at different concentrations. At moderate concentration, ROS activates the cancer cell survival signaling cascade involving mitogen-activated protein kinase/extracellular signal-regulated protein kinases 1/2 (MAPK/ERK1/2), p38, c-Jun N-terminal kinase (JNK), and phosphoinositide-3-kinase/ protein kinase B (PI3K/Akt), which in turn activate the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), matrix metalloproteinases (MMPs), and vascular endothelial growth factor (VEGF). At high concentrations, ROS can cause cancer cell apoptosis. Hence, it critically depends upon the ROS levels, to either augment tumorigenesis or lead to apoptosis. The major issue is targeting the dual actions of ROS effectively with respect to the concentration bias, which needs to be monitored carefully to impede tumor angiogenesis and metastasis for ROS to serve as potential therapeutic targets exogenously/endogenously. Overall, additional research is required to comprehend the potential of ROS as an effective anti-tumor modality and therapeutic target for treating malignancies.

Dietary compound glycyrrhetinic acid suppresses tumor angiogenesis and growth by modulating antiangiogenic and proapoptotic pathways in vitro and in vivo

Glycyrrhetinic acid (GA) is a major bioactive compound of licorice. The objective of this study was to investigate the effects of GA on ovarian cancer, particularly those related to angiogenesis and apoptosis, and to elucidate the underlying mechanisms of action. In vitro studies showed that GA significantly inhibited proliferation, migration, invasion and tube formation in human umbilical vein endothelial cells (HUVECs) in a concentration-dependent manner. GA inhibited the phosphorylation of major receptors and enzymes involved in angiogenesis, such as VEGFR2, mTOR, Akt, ERK1/2, MEK1/2, p38 and JNK1/2 in HUVECs. In addition, GA induced apoptosis, loss of mitochondrial membrane potential and cell cycle arrest in G1 phase in A2780 ovarian cancer cells. The proapoptotic effect of GA involved the increased phosphorylation of p38 and JNK1/2; increased cleavage of caspase 3, caspase 9 and PARP; reduced phosphorylation of mTOR, Akt and ERK1/2; and reduced expressions of survivin and cyclin D1. Ex vivo studies showed that GA significantly inhibited microvessel sprouting in rat aortic ring model. In vivo studies showed that GA inhibited the formation of new blood vessels in zebrafish and mouse Matrigel plug. GA also significantly reduced the size of ovarian cancer xenograft tumors in nude mice. Taken together, GA possesses potential antitumor effects, and the underlying mechanisms may involve the inhibition of signaling pathways related to angiogenesis and the activation of apoptotic pathways in cancer cells. Our findings suggest that GA could serve as an effective regimen in the prevention or treatment of cancer.

Eriocalyxin B Biological Activity: A Review on Its Mechanism of Action

Natural products, a rich source of bioactive chemical compounds, have served humans as a safer drug of choice since times. Eriocalyxin B, an ent-Kaurene diterpenoid, has been extracted from a traditional Chinese herb Isodon eriocalyx. Experimental data support the anticancer and anti-inflammatory activities of EriB. This natural entity exhibits anticancer effects against breast, pancreatic, leukemia, ovarian, lung, bladder, and colorectal cancer. EriB has capability to inhibit the proliferation of cancer cells by prompting apoptosis, arresting cell cycle, and modulating cell signaling pathways. The regulation of signaling pathways in cancerous cells by EriB involves the modulation of various apoptosis-related factors (Bak, Bax, caspases, XIAP, survivin, and Beclin-1), transcriptional factors (nuclear factor kappa B [NF-κB], STAT3, Janus-activated kinase 2, Notch, AP-1, and lκBα), enzymes (cyclooxygenase 2, matrix metalloproteinase 2 [MMP-2], MMP-9, and poly (ADP-ribose) polymerase), cytokines, and protein kinases (mitogen-activated protein kinase and ERK1/2). This review proposes that EriB supplies a novel opportunity for the cure of cancer but supplementary investigations along with preclinical trials are obligatory to effectively figure out its biological and pharmacological applications.

Overexpression of ribonuclease inhibitor induces autophagy in human colorectal cancer cells via the Akt/mTOR/ULK1 pathway

Ribonuclease inhibitor (RI), also termed angiogenin inhibitor, acts as the inhibitor of ribonucleolytic activity of RNase A and angiogenin. The expression of RI has been investigated in melanoma and bladder cancer cells. However, the precise role of RI in tumorigenesis, in addition to RI‑induced autophagy, remains poorly understood. In the present study, it was demonstrated that RI positively regulated autophagy in human colorectal cancer (CRC) cells as indicated by an increase in light chain 3 (LC3)‑II levels. Furthermore, RI regulated cell survival in HT29 cells. In addition, autophagy‑associated proteins, including beclin‑1 and autophagy‑related protein 13, were increased in response to RI‑induced autophagy, and the protein kinase B (Akt)/mechanistic target of rapamycin (mTOR)/Unc‑51 like autophagy activating kinase (ULK1) pathway may be involved in the activation of autophagy induced by RI overexpression. Taken together, the evidence of the present study indicated that the overexpression of RI induced ATG‑dependent autophagy in CRC cells via the Akt/mTOR/ULK1 pathway, suggesting that the upregulation of RI activity may constitute a novel approach for the treatment of human colorectal carcinoma.

Maoeriocalysins A–D, four novelent-kaurane diterpenoids fromIsodon eriocalyxand their structure determination utilizing quantum chemical calculation in conjunction with quantitative interproton distance analysis

Maoeriocalysin A, an unprecedented 4,5-seco-3,5-cyclo-7,20-epoxy-ent-kauranoid, together with three rare 9,10-seco-ent-kauranoids, maoeriocalysins B–D, were isolated.

WZY-321, a novel evodiamine analog, inhibits glioma cell growth in an autophagy-associated manner

Glioblastoma is one of the most aggressive types of brain tumor. The median survival rate of patients with glioblastoma (World Health Organization grade IV) is <15 months. Therefore, there is an urgent requirement for the development of novel and efficient therapeutic agents against glioma. In previous studies, WZY-321 (10-hydroxy-1-methyl-8,13b-dihydro-5H,7H-benzo[e]benzofuro[2',3':3,4]pyrido[2,1-b][1,3]oxazin-5-one), a novel evodiamine (Evo) analog, was reported to exhibit enhanced pharmacological properties and improved cytotoxicity against a number of human cancer cell lines compared with Evo. In the current study, the anti-proliferative effect of WZY-321 on SHG-44 and SWO-38 glioma cells was further studied, and its mechanism of action investigated. The results indicated that WZY-321 inhibited the proliferation of SHG-44 cells in a dose- and time-dependent manner by enhancing cellular apoptosis and inducing cell cycle arrest at the G2-M phase. Treatment of glioma cells with WZY-321 concomitantly increased the expression levels of microtubule associated protein 1 light chain 3α and Beclin1, indicating enhanced autophagy. Overall, the results of the present study revealed the anti-proliferative potential of WZY-321 in glioma cells, thus providing a possible autophagy-based therapeutic strategy for the treatment of glioblastoma.

Tumour growth and immune evasion as targets for a new strategy in advanced cancer

It has become clearer that advanced cancer, especially advanced breast cancer, is an entirely displayed pathological system that is much more complex than previously considered. However, the direct relationship between tumour growth and immune evasion can represent a general rule governing the pathological cancer system from the initial cancer cells to when the system is entirely displayed. Accordingly, a refined pathobiological model and a novel therapeutic strategy are proposed. The novel therapeutic strategy is based on therapeutically induced conditions (undetectable tumour burden and/or a prolonged tumour ‘resting state’), which enable an efficacious immune response in advanced breast and other types of solid cancers.

Autophagy and its potent modulators from phytochemicals in cancer treatment

Autophagy is a ubiquitous catabolic process by which damaged or harmful intracellular components are delivered to the lysosomes for self-digestion and recycling. It is critical in cancer treatment. Therapy-induced autophagy predominantly acts as a pro-survival mechanism, but progressive autophagy can lead to non-apoptotic cell death, also known as autophagic cell death. Plants or herbs contain various natural compounds that are widely used in the treatment of many types of malignancies. Emerging evidence indicates that phytochemicals targeting the autophagic pathway are promising agents for cancer treatment. However, these compounds play different roles in autophagy. In this review, we discussed the role of autophagy in cancer development and therapy, and focussed on elucidating the anti-cancer activities of autophagic modulators, especially phytochemicals. Notably, we described a novel premise that the dynamic role of phytochemicals should be evaluated in regulation of autophagy in cancer.

A natural ent‑kaurane diterpenoid induces antiproliferation in ovarian cancer cells via ERK1/2 regulation and inhibition of cellular migration and invasion

Ovarian cancer is one of the most common causes of female mortalities from gynecological tumors. An ent‑kaurane diterpenoid compound CRT1 (ent‑18‑acetoxy‑7β‑hydroxy kaur‑15‑oxo‑16‑ene), mainly isolated from the Vietnamese herb Croton tonkinesis has been used in folk medicine in Vietnam for cancer treatment. However, the effect of this compound on human ovarian cancer cells has not yet been reported. The objective of the present study was to determine the effect of CRT1 on the cell viability, apoptosis and metastasis of SKOV3 human ovarian cancer cells using a Cell Counting Kit‑8 assay, flow cytometric analysis of Annexin V‑fluorescein isothiocyanate/propidium iodide staining, western blot analysis, soft agar colony forming assay, wound healing assay and Matrigel invasion assay. The results revealed that CRT1 possessed significant anti‑proliferative effects on SKOV3 cells. CRT1 treatment at 25 and 50 µM induced apoptosis, enhanced the percentage of Annexin V‑positive cells, increased the expression of pro‑apoptotic protein B‑cell lymphoma 2 (Bcl‑2)‑associated X protein, cytochrome c release from the mitochondria to the cytosol, cleaved caspase‑3, caspase‑7, caspase‑9, and poly (adenosine diphosphate‑ribose) polymerase. However, it decreased the expression of Bcl‑2 in a dose‑dependent manner. The percentage of necrotic cells increased following CRT1 treatment at <10 µM. CRT1 at 50 µM significantly induced the phosphorylation of extracellular signal‑regulated kinase (ERK). Growth inhibition and the apoptotic effects of CRT1 could be reversed by PD98059, an ERK inhibitor. Additionally, CRT1 inhibited cell migration and invasion via ERK1/2 activation in SKOV3 cells. These results indicated that CRT1, an ent‑kaurane diterpenoid, may be a potential inhibitor of ovarian cancer by the activating ERK1/2/p90 ribosomal S6 kinase signaling pathway.

Targeting VEGF/VEGFRs Pathway in the Antiangiogenic Treatment of Human Cancers by Traditional Chinese Medicine

Bearing in mind the doctrine of tumor angiogenesis hypothesized by Folkman several decades ago, the fundamental strategy for alleviating numerous cancer indications may be the strengthening application of notable antiangiogenic therapies to inhibit metastasis-related tumor growth. Under physiological conditions, vascular sprouting is a relatively infrequent event unless when specifically stimulated by pathogenic factors that contribute to the accumulation of angiogenic activators such as the vascular endothelial growth factor (VEGF) family and basic fibroblast growth factor (bFGF). Since VEGFs have been identified as the principal cytokine to initiate angiogenesis in tumor growth, synthetic VEGF-targeting medicines containing bevacizumab and sorafenib have been extensively used, but prominent side effects have concomitantly emerged. Traditional Chinese medicines (TCM)–derived agents with distinctive safety profiles have shown their multitarget curative potential by impairing angiogenic stimulatory signaling pathways directly or eliciting synergistically therapeutic effects with anti-angiogenic drugs mainly targeting VEGF-dependent pathways. This review aims to summarize (a) the up-to-date understanding of the role of VEGF/VEGFR in correlation with proangiogenic mechanisms in various tissues and cells; (b) the elaboration of antitumor angiogenesis mechanisms of 4 representative TCMs, including Salvia miltiorrhiza, Curcuma longa, ginsenosides, and Scutellaria baicalensis; and (c) circumstantial clarification of TCM-driven therapeutic actions of suppressing tumor angiogenesis by targeting VEGF/VEGFRs pathway in recent years, based on network pharmacology.

Role of autophagy in breast cancer and breast cancer stem cells (Review)

Autophagy is a key catabolic process, in which cytosolic cargo is engulfed by the formation of a double membrane and then degraded through the fusing of autophagosomes with lysosomes. Autophagy is a constitutively active, evolutionarily conserved, catabolic process important for the maintenance of homeostasis in cellular stress responses and cell survival. Although the mechanisms of autophagy have not yet been fully elucidated, emerging evidence suggests that it plays a dual role in breast cancer and in maintaining the activity of breast cancer stem cells (CSCs). However, it may play a complex role in breast CSC therapy. Breast CSCs, a population of cells with the ability to self-renew, differentiate, and initiate and sustain tumor growth, play an essential role in cancer recurrence, anticancer resistance and metastasis. In addition, the elucidation of the association between autophagy and apoptosis in the tumor context is crucial in order to better address appropriate therapy strategies. In the present review, a summary of the mechanisms and roles of autophagy in breast cancer and CSCs is presented. The potential value of such autophagy modulators in the development of novel breast cancer therapies is discussed.

Functional roles of eriocalyxin B in zebrafish revealed by transcriptome analysis

Eriocalyxin B (EriB) is a naturalent-kaurane diterpenoid obtained fromIsodon eriocalyxvar.laxiflora(family Lamiaceae), which exerted multiple biological activities (e.g.anti-tumor and anti-inflammatory)viathe alteration of gene expression and signaling transduction.

New Insights into the Role of Autophagy in Tumor Immune Microenvironment

The tumor microenvironment is a complex system that is affected by various factors, including hypoxia, acidosis, and immune and inflammatory responses, which have significant effects on tumor adhesion, invasion, metastasis, angiogenesis, and autophagy. In this hostile tumor microenvironment, autophagy of tumor cells can promote tumor growth and metastasis. As autophagy is a double-edged sword in tumors, treatment of cancer via regulation of autophagy is extremely complicated. Therefore, understanding the relationship between tumor autophagy and the tumor microenvironment is extremely important. As the immune milieu plays an important role in tumor development, immunotherapy has become a promising form of cancer therapy. A multi-pronged treatment approach using immunotherapy and molecular targets may become the major direction for future cancer treatments. This article reviews existing knowledge regarding the immune factors in the tumor microenvironment and the status of tumor autophagy research.