Curcumin analog WZ35 induced cell death via ROS-dependent ER stress and G2/M cell cycle arrest in human prostate cancer cells

Anticancer perspectives of monocarbonyl analogs of curcumin: A decade (2014-2024) review

Monocarbonyl analogs of curcumin (MACs) represent structurally modified versions of curcumin. The existing literature indicates that MACs exhibit enhanced anticancer properties compared with curcumin. Numerous research articles in recent years have emphasized the significance of MACs as effective anticancer agents. This review focuses on the latest advances in the anticancer potential of MACs, from 2014 to 2024, including discussions on their mechanism of action, structure-activity relationship (SAR), and in silico molecular docking studies.

Cucurbitacin E elicits apoptosis in laryngeal squamous cell carcinoma by enhancing reactive oxygen species-regulated mitochondrial dysfunction and endoplasmic reticulum stress

Laryngeal squamous cell carcinoma (LSCC) is a prevalent head and neck neoplasm with escalating global morbidity and mortality rates. Despite the increasing burden of LSCC, the drugs currently approved for its treatment are limited. Therefore, it is necessary to identify novel and promising drugs that target LSCC. Cucurbitacin E (CuE) is a naturally oxygenated tetracyclic triterpenoid that suppresses several cancers. However, its anti-LSCC activity and the molecular mechanisms of action remain unclear. This study explored its impact on LSCC, revealing cell viability attenuation and apoptosis enhancement in vitro. Further investigations indicated that CuE significantly decreased mitochondrial membrane potential, thereby promoting cytochrome c release, increasing cleaved-Caspase 3 and cleaved-PARP levels, and triggering mitochondria-dependent apoptosis. Concurrently, exposure of LSCC cells to CuE enhanced endoplasmic reticulum (ER) stress, mobilized the protein kinase RNA-like endoplasmic reticulum kinase/initiation factor 2a/ATF4/C-EBP homologous protein pathway, and induced LSCC cell apoptosis. Finally, CuE markedly elevated intracellular reactive oxygen species (ROS) levels. When ROS were eliminated with N-acetylcysteine, CuE-mediated mitochondrial dysfunction, ER stress, and cell apoptosis were nearly abolished. Similar outcomes were observed in murine LSCC models. Together, these results highlight that CuE suppresses proliferation while triggering apoptosis in LSCC cells via ROS-regulated mitochondrial dysfunction and the ER stress pathway. Hence, CuE may serve as a promising candidate for LCSS treatment.

Inhibition of the thioredoxin system for radiosensitization therapy of cancer

Radiotherapy (RT) stands as a cornerstone in the clinical armamentarium against various cancers due to its proven efficacy. However, the intrinsic radiation resistance exhibited by cancer cells, coupled with the adverse effects of RT on normal tissues, often compromises its therapeutic potential and leads to unwanted side effects. This comprehensive review aims to consolidate our understanding of how radiosensitizers inhibit the thioredoxin (Trx) system in cellular contexts. Notable radiosensitizers, including gold nanoparticles (GNPs), gold triethylphosphine cyanide ([Au(SCN) (PEt3)]), auranofin, ceria nanoparticles (CONPs), curcumin and its derivatives, piperlongamide, indolequinone derivatives, micheliolide, motexafin gadolinium, and ethane selenide selenidazole derivatives (SeDs), are meticulously elucidated in terms of their applications in radiotherapy. In this review, the sensitization mechanisms and the current research progress of these radiosensitizers are discussed in detail, with the overall aim of providing valuable insights for the judicious application of Trx system inhibitors in the field of cancer radiosensitization therapy.

Targeting YAP1 to improve the efficacy of immune checkpoint inhibitors in liver cancer: mechanism and strategy

Liver cancer is the third leading of tumor death, including hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC). Immune checkpoint inhibitors (ICIs) are yielding much for sufferers to hope for patients, but only some patients with advanced liver tumor respond. Recent research showed that tumor microenvironment (TME) is critical for the effectiveness of ICIs in advanced liver tumor. Meanwhile, metabolic reprogramming of liver tumor leads to immunosuppression in TME. These suggest that regulating the abnormal metabolism of liver tumor cells and firing up TME to turn "cold tumor" into "hot tumor" are potential strategies to improve the therapeutic effect of ICIs in liver tumor. Previous studies have found that YAP1 is a potential target to improve the efficacy of anti-PD-1 in HCC. Here, we review that YAP1 promotes immunosuppression of TME, mainly due to the overstimulation of cytokines in TME by YAP1. Subsequently, we studied the effects of YAP1 on metabolic reprogramming in liver tumor cells, including glycolysis, gluconeogenesis, lipid metabolism, arachidonic acid metabolism, and amino acid metabolism. Lastly, we summarized the existing drugs targeting YAP1 in the treatment of liver tumor, including some medicines from natural sources, which have the potential to improve the efficacy of ICIs in the treatment of liver tumor. This review contributed to the application of targeted YAP1 for combined therapy with ICIs in liver tumor patients.

Effects of curcumin and ursolic acid in prostate cancer: A systematic review

The major barriers to phytonutrients in prostate cancer therapy are non-specific mechanisms and bioavailability issues. Studies have pointed to a synergistic combination of curcumin (CURC) and ursolic acid (UA). We investigate this combination using a systematic review process to assess the most likely mechanistic pathway and human testing in prostate cancer. We used the PRISMA statement to screen titles, abstracts, and the full texts of relevant articles and performed a descriptive analysis of the literature reviewed for study inclusion and consensus of the manuscript. The most common molecular and cellular pathway from articles reporting on the pathways and effects of CURC (n = 173) in prostate cancer was NF-κB (n = 25, 14.5%). The most common molecular and cellular pathway from articles reporting on the pathways and effects of UA (n = 24) in prostate cancer was caspase 3/caspase 9 (n = 10, 41.6%). The three most common molecular and cellular pathway from articles reporting on the pathways and effects of both CURC and UA (n = 193) in prostate cancer was NF-κB (n = 28, 14.2%), Akt (n = 22, 11.2%), and androgen (n = 19, 9.6%). Therefore, we have identified the potential synergistic target pathways of curcumin and ursolic acid to involve NF-κB, Akt, androgen receptors, and apoptosis pathways. Our review highlights the limited human studies and specific effects in prostate cancer.

Mitocurcumin utilizes oxidative stress to upregulate JNK/p38 signaling and overcomes Cytarabine resistance in acute myeloid leukemia

Acute myeloid leukemia (AML) is a type of blood cancer that is characterized by the rapid growth of abnormal myeloid cells. The goal of AML treatment is to eliminate the leukemic blasts, which is accomplished through intensive chemotherapy. Cytarabine is a key component of the standard induction chemotherapy regimen for AML. However, despite a high remission rate, 70-80% of AML patients relapse and develop resistance to Cytarabine, leading to poor clinical outcomes. Mitocurcumin (MitoC), a derivative of curcumin that enters mitochondria, leading to a drop in mitochondrial membrane potential and mitophagy induction. Further, it activates oxidative stress-mediated JNK/p38 signaling to induce apoptosis. MitoC demonstrated a preferential ability to kill leukemic cells from AML cell lines and patient-derived leukemic blasts. RNA sequencing data suggests perturbation of DNA damage response and cell proliferation pathways in MitoC-treated AML. Elevated reactive oxygen species (ROS) in MitoC-treated AML cells resulted in significant DNA damage and cell cycle arrest. Further, MitoC treatment resulted in ROS-mediated enhanced levels of p21, which leads to suppression of CHK1, RAD51, Cyclin-D and c-Myc oncoproteins, potentially contributing to Cytarabine resistance. Combinatorial treatment of MitoC and Cytarabine has shown synergism, increased apoptosis, and enhanced DNA damage. Using AML xenografts, a significant reduction of hCD45+ cells was observed in AML mice bone marrow treated with MitoC (mean 0.6%; range0.04%-3.56%) compared to control (mean 38.2%; range10.1%-78%), p = 0.03. The data suggest that MitoC exploits stress-induced leukemic oxidative environment to up-regulate JNK/p38 signaling to lead to apoptosis and can potentially overcome Cytarabine resistance via ROS/p21/CHK1 axis.

Cancer Metabolism: The Role of ROS in DNA Damage and Induction of Apoptosis in Cancer Cells

Cancer is a huge challenge for people worldwide. High reactive oxygen species (ROS) levels are a recognized hallmark of cancer and an important aspect of cancer treatment research. Abnormally elevated ROS levels are often attributable to alterations in cellular metabolic activities and increased oxidative stress, which affects both the development and maintenance of cancer. Moderately high levels of ROS are beneficial to maintain tumor cell genesis and development, while toxic levels of ROS have been shown to be an important force in destroying cancer cells. ROS has become an important anticancer target based on the proapoptotic effect of toxic levels of ROS. Therefore, this review summarizes the role of increased ROS in DNA damage and the apoptosis of cancer cells caused by changes in cancer cell metabolism, as well as various anticancer therapies targeting ROS generation, in order to provide references for cancer therapies based on ROS generation.

Oxidative Stress Inducers in Cancer Therapy: Preclinical and Clinical Evidence

Reactive oxygen species (ROS) are metabolic byproducts that regulate various cellular processes. However, at high levels, ROS induce oxidative stress, which in turn can trigger cell death. Cancer cells alter the redox homeostasis to facilitate protumorigenic processes; however, this leaves them vulnerable to further increases in ROS levels. This paradox has been exploited as a cancer therapeutic strategy with the use of pro-oxidative drugs. Many chemotherapeutic drugs presently in clinical use, such as cisplatin and doxorubicin, induce ROS as one of their mechanisms of action. Further, various drugs, including phytochemicals and small molecules, that are presently being investigated in preclinical and clinical studies attribute their anticancer activity to ROS induction. Consistently, this review aims to highlight selected pro-oxidative drugs whose anticancer potential has been characterized with specific focus on phytochemicals, mechanisms of ROS induction, and anticancer effects downstream of ROS induction.

ROS/ER stress contributes to trimethyltin chloride-mediated hepatotoxicity; Tea polyphenols alleviate apoptosis and immunosuppression

Trimethyltin chloride (TMT) is an organotin-based contaminant present in the water environment that poses a great threat to aquatic organisms and humans. The liver is the detoxification organ of the body and TMT exposure accumulates in the liver. Tea polyphenol (TP) is a natural antioxidant extracted from tea leaves and has been widely used as a food and feed additive. To investigate the mechanism of toxicity caused by TMT exposure on grass carp hepatocytes (L8824 cells) and the mitigating effect of TP, we established a hepatocyte model of TMT toxicity and/or TP treatment. L8824 cells were treated with 0.5 μM of TMT and/or 4 μg/mL of TP for 24 h and assayed for relevant indices. The results showed that TMT exposure caused oxidative stress, resulting in increased intracellular ROS content, resulting in intracellular ROS accumulation and increased MDA content, and inhibiting the activities of T-AOC, SOD, CAT, and GSH. Meanwhile, TMT exposure activated the endoplasmic reticulum apoptotic signaling pathway, resulting in abnormal expression of GRP78, ATF-6, IRE1, PERK, Caspase-3 and Caspase-12. In addition, TMT exposure also led to up-regulation of cytokines IL-1β, IL-6, TNF-α, and decreased expression of IL-2, IFN-γ, and antimicrobial peptides Hepcidin, β-defensin, and LEAP2. However, the addition of TP could mitigate the above changes. In conclusion, TP can alleviate TMT exposure-mediated hepatotoxicity by inhibiting ROS/ER stress in L8824 cells. In addition, this trial enriches the cytotoxicity study of TMT and provides a new theoretical basis for the use of TP as a mitigating agent for TMT.

Monocarbonyl Curcumin Analogues as Potent Inhibitors against Human Glutathione Transferase P1-1

The isoenzyme of human glutathione transferase P1-1 (hGSTP1-1) is involved in multi-drug resistance (MDR) mechanisms in numerous cancer cell lines. In the present study, the inhibition potency of two curcuminoids and eleven monocarbonyl curcumin analogues against hGSTP1-1 was investigated. Demethoxycurcumin (Curcumin II) and three of the monocarbonyl curcumin analogues exhibited the highest inhibitory activity towards hGSTP1-1 with IC₅₀ values ranging between 5.45 ± 1.08 and 37.72 ± 1.02 μM. Kinetic inhibition studies of the most potent inhibitors demonstrated that they function as non-competitive/mixed-type inhibitors. These compounds were also evaluated for their toxicity against the prostate cancer cells DU-145. Interestingly, the strongest hGSTP1-1 inhibitor, (DM96), exhibited the highest cytotoxicity with an IC₅₀ of 8.60 ± 1.07 μΜ, while the IC₅₀ values of the rest of the compounds ranged between 44.59-48.52 μΜ. Structural analysis employing molecular docking, molecular dynamics (MD) simulations, and binding-free-energy calculations was performed to study the four most potent curcumin analogues as hGSTP1-1 inhibitors. According to the obtained computational results, DM96 exhibited the lowest binding free energy, which is in agreement with the experimental data. All studied curcumin analogues were found to form hydrophobic interactions with the residue Gln52, as well as hydrogen bonds with the nearby residues Gln65 and Asn67. Additional hydrophobic interactions with the residues Phe9 and Val36 as well as π-π stacking interaction with Phe9 contributed to the superior inhibitory activity of DM96. The van der Waals component through shape complementarity was found to play the most important role in DM96-inhibitory activity. Overall, our results revealed that the monocarbonyl curcumin derivative DM96 acts as a strong hGSTP1-1 inhibitor, exerts high prostate cancer cell cytotoxicity, and may, therefore, be exploited for the suppression and chemosensitization of cancer cells. This study provides new insights into the development of safe and effective GST-targeted cancer chemosensitizers.

ROS-generating, pH-responsive and highly tunable reduced graphene oxide-embedded microbeads showing intrinsic anticancer properties and multi-drug co-delivery capacity for combination cancer therapy

The development of effective carriers enabling combination cancer therapy is of practical importance due to its potential to enhance the effectiveness of cancer treatment. However, most of the reported carriers are monofunctional in nature. The carriers that can be applied to concomitantly mediate multiple treatment modalities are highly deficient. This study fills this gap by reporting the design and fabrication of ROS-generating carbohydrate-based pH-responsive beads with intrinsic anticancer therapy and multidrug co-delivery capacity for combination cancer therapy. Sodium alginate (SA) microspheres and reduced graphene oxide (rGO)-embedded chitosan (CS) beads are developed via emulsion-templated ionic gelation for a combination therapy involving co-delivery of curcumin (CUR) and 5-fluororacil (5-FU). Drug-encapsulated microbeads are characterized by FTIR, DSC, TGA, XRD, and SEM. 5-FU and CUR-encapsulated microbeads are subjected to in vitro drug release studies at pH 6.8 and 1.2 at 37 °C. Various release kinetic parameters are evaluated. The results show that the Korsmeyer-Peppas model and non-Fickian release kinetics are best suited. The microspheres and microbeads are found to effectively act against MCF7 cells and show intrinsic anticancer capacity. These results indicate the promising performance of our beads in mediating combination drug therapy to improve the effectiveness of cancer treatment.

The Impact of Oxidative Stress and AKT Pathway on Cancer Cell Functions and Its Application to Natural Products

Oxidative stress and AKT serine-threonine kinase (AKT) are responsible for regulating several cell functions of cancer cells. Several natural products modulate both oxidative stress and AKT for anticancer effects. However, the impact of natural product-modulating oxidative stress and AKT on cell functions lacks systemic understanding. Notably, the contribution of regulating cell functions by AKT downstream effectors is not yet well integrated. This review explores the role of oxidative stress and AKT pathway (AKT/AKT effectors) on ten cell functions, including apoptosis, autophagy, endoplasmic reticulum stress, mitochondrial morphogenesis, ferroptosis, necroptosis, DNA damage response, senescence, migration, and cell-cycle progression. The impact of oxidative stress and AKT are connected to these cell functions through cell function mediators. Moreover, the AKT effectors related to cell functions are integrated. Based on this rationale, natural products with the modulating abilities for oxidative stress and AKT pathway exhibit the potential to regulate these cell functions, but some were rarely reported, particularly for AKT effectors. This review sheds light on understanding the roles of oxidative stress and AKT pathway in regulating cell functions, providing future directions for natural products in cancer treatment.

Natural Products as the Modulators of Oxidative Stress: An Herbal Approach in the Management of Prostate Cancer

Prostate cancer is the most commonly diagnosed and frequently occurred cancer in the males globally. The current treatment strategies available to treat prostate cancer are not much effective and express various adverse effects. Hence, there is an urgent need to identify novel treatment that can improve patient outcome. From times immemorial, natural products are highly recognized for novel drug development for various diseases including cancer. Cancer cells generally maintain higher basal levels of reactive oxygen species (ROS) when compared to normal cells due to its high metabolic rate. However, initiation of excess intracellular ROS production can not be tolerated by the cancer cells and induce several cell death signals which are in contrast to normal cells. Therefore, small molecules of natural origin that induce ROS can potentially kill cancer cells in specific and provide a better opportunity to develop a novel drug therapy. In this review, we elaborated various classes of medicinal compounds and their mechanism of killing prostate cancer cells through direct or indirect ROS generation. This can generate a novel thought to develop promising drug candidate to treat prostate cancer patients.

Oxidative Stress Induced Cell Cycle Arrest: Potential Role of PRX-2 and GSTP-1 as Therapeutic Targets in Hepatocellular Carcinoma

BACKGROUND

The increasing incidence and mortality rate of HCC is a major concern, especially for developing countries of the world. Hence, extensive research is being carried out in order to explore new approaches for developing successful therapeutic strategies for HCC. The controversial role of oxidative stress in the prognosis and treatment of various diseases such as cancer has become the area of great interest and intrigue for many scientists throughout the world.

OBJECTIVE

We aim to investigate the role of induced oxidative stress on the suppression of HCC Huh-7 cancerous cells as therapeutic approach.

METHODS

Induction of oxidative stress via H2O2 treatment produced cell cytotoxicity in a dose dependent manner and also led to the over expression of GSTP-1 and PRX-2. The expression of GSTP-1 and PRX-2 was compared in HCC Huh-7 treated, untreated cells and normal hepatocytes using immunocytochemistry. Furthermore, the effects of oxidative stress on cell cycle arrest were also studied through flow cytometry.

RESULTS

Our study demonstrated the inhibition of cancer cell proliferation as a result of H2O2 induction by arresting the cell cycle at G2 phase.

CONCLUSION

The induction of oxidative stress could be a potential therapeutic approach for treating HCC in the future. GSTP-1 and PRX-2 can serve as substantial therapeutic targets for the treatment of HCC.

Diarylpentanoid (1,5-bis(4-hydroxy-3-methoxyphenyl)-1,4-pentadiene-3-one) (MS13) Exhibits Anti-proliferative, Apoptosis Induction and Anti-migration Properties on Androgen-independent Human Prostate Cancer by Targeting Cell Cycle-Apoptosis and PI3K Signalling Pathways

Diarylpentanoids exhibit a high degree of anti-cancer activity and stability in vitro over curcumin in prostate cancer cells. Hence, this study aims to investigate the effects of a diarylpentanoid, 1,5-bis(4-hydroxy-3-methoxyphenyl)-1,4-pentadiene-3-one (MS13) on cytotoxicity, anti-proliferative, apoptosis-inducing, anti-migration properties, and the underlying molecular mechanisms on treated androgen-independent prostate cancer cells, DU 145 and PC-3. A cell viability assay has shown greater cytotoxicity effects of MS13-treated DU 145 cells (EC₅₀ 7.57 ± 0.2 µM) and PC-3 cells (EC₅₀ 7.80 ± 0.7 µM) compared to curcumin (EC₅₀: DU 145; 34.25 ± 2.7 µM and PC-3; 27.77 ± 6.4 µM). In addition, MS13 exhibited significant anti-proliferative activity against AIPC cells compared to curcumin in a dose- and time-dependent manner. Morphological observation, increased caspase-3 activity, and reduced Bcl-2 protein levels in these cells indicated that MS13 induces apoptosis in a time- and dose-dependent. Moreover, MS13 effectively inhibited the migration of DU 145 and PC-3 cells. Our results suggest that cell cycle-apoptosis and PI3K pathways were the topmost significant pathways impacted by MS13 activity. Our findings suggest that MS13 may demonstrate the anti-cancer activity by modulating DEGs associated with the cell cycle-apoptosis and PI3K pathways, thus inhibiting cell proliferation and cell migration as well as inducing apoptosis in AIPC cells.

Endoplasmic reticulum stress, cell death and tumor: Association between endoplasmic reticulum stress and the apoptosis pathway in tumors (Review)

External and internal stimuli are often involved in the pathogenesis of tumors, and the deterioration of endoplasmic reticulum (ER) function within cells is also an important etiological factor of tumorigenesis resulting in the impairment of the endoplasmic reticulum, which is termed ER stress. The ER is an organelle that serves a crucial role in the process of protein synthesis and maturation, and also acts as a reservoir of calcium to maintain intracellular Ca2+ homeostasis. ER stress has been revealed to serve a critical role in tumorigenesis. In the present review, the association between ER stress‑related pathways and tumor cell apoptosis is examined. Primarily, the role of ER stress in tumor cell apoptosis is discussed, and it is stipulated that ER stress, induced by drugs both directly and indirectly, promotes tumor cell apoptosis.

Increased Tumoral Microenvironmental pH Improves Cytotoxic Effect of Pharmacologic Ascorbic Acid in Castration-Resistant Prostate Cancer Cells

Background

The anticancer potential of pharmacologic ascorbic acid (AA) has been detected in a number of cancer cells. However, in vivo study suggested a strongly reduced cytotoxic activity of AA. It was known that pH could be a critical influencing factor for multiple anticancer treatments. In this study, we explored the influence of pH on the cytotoxicity of ascorbic acid. We employed castration-resistant prostate cancer (CRPC) cell lines PC3 and DU145 to observe the therapeutic effect of AA on PCa cells that were cultured with different pH in vitro. We also analyzed the influence of pH and extracellular oxidation on cytotoxicity of AA in cancer cells using reactive oxygen species (ROS) assay, cellular uptake of AA, and NADPH assay. Male BALB/c nude mice bearing prostate carcinoma xenografts (PC3 or DU145) were used to assess treatment response to AA with or without bicarbonate in vivo. The cellular uptake of AA in PCa xenografts was detected using positron emission tomography (PET). Small animal PET/CT scans were performed on mice after the administration of 6-deoxy-6-[¹⁸F] fluoro-L-ascorbic acid (¹⁸F-DFA).

Results

Our in vitro studies demonstrate that acidic pH attenuates the cytotoxic activity of pharmacologic ascorbic acid by inhibiting AA uptake in PCa cells. Additionally, we found that the cancer cell-selective toxicity of AA depends on ROS. In vivo, combination of AA and bicarbonate could provide a significant better therapeutic outcome in comparison with controls or AA single treated mice. ¹⁸F-DFA PET imaging illustrated that the treatment with NaHCO₃ could significantly increase the AA uptake in tumor.

Conclusions

The alkalinity of tumor microenvironment plays an important role in anticancer efficiency of AA in CRPC. ¹⁸F-DFA PET/CT imaging could predict the therapeutic response of PCa animal model through illustration of tumoral uptake of AA. ¹⁸F-DFA might be a potential PET tracer in clinical diagnosis and treatment for CRPC.

Synthesis and in-vitro anti-cancer evaluations of multi-methoxylated asymmetrical diarylpentanoids as intrinsic apoptosis inducer against colorectal cancer

In the present study, a series of nine stable 3,4,5-methoxylphenyl-containing asymmetrical diarylpentanoids, derivatives of curcuminoids, have been synthesized, characterized and evaluated for their in-vitro anti-cancer potential against a panel of BRAF- and KRAS-mutated colorectal cancer cell lines including T84, LoVo and SW620, HT29, RKO and NCI-H508, respectively. Structure-activity relationship study on cytotoxicity of tested compounds suggested that the presence of meta-hydroxyl and adjacent dimethoxyl groups are crucial for enhanced cytotoxicity of diarylpentanoids. Among the evaluated analogs, 8 has been identified as the lead compound due to its highest chemotherapeutic index of 9.9 and nano molar scale cytotoxicity against SW620 and RKO. Colonies formation and cell cycle analyses on 8-treated RKO cells showed that 8 exhibits strong anti-proliferative activity by inducing G2/M-phase cell arrest. Subsequent flow cytometry based annexin-V and DCFHDA studies suggested that 8 could induce apoptosis through intracellular ROS-dependent pathway. Further Western blot studies confirmed that 8 has induced intrinsic apoptosis in RKO cells through the up-regulations of Bad and Bax pro-apoptotic proteins and down-regulations of Bcl-2 and Bcl-xL pro-survival proteins. In all, the present results suggest that 8 could be a potent lead which deserves further modification and investigation in the development of small molecule-based anti-colorectal cancer agents.

Impact of curcumin on replicative and chronological aging in the Saccharomyces cerevisiae yeast

Curcumin is a biologically active compound of vegetable origin which has a hormetic effect. Pro-health and anti-aging properties of curcumin have been known for years. The main benefit of curcumin is thought to be its anti-oxidative action. Despite vast amount of data confirming age-delaying activity of curcumin in various groups of organisms, so far little has been discovered about curcumin's impact on cell aging in the experimental model of the Saccharomyces cerevisiae budding yeast. We have been able to demonstrate that curcumin significantly increases oxidative stress and accelerates replicative and chronological aging of yeast cells devoid of anti-oxidative protection (with SOD1 and SOD2 gene deletion) and deprived of DNA repair mechanisms (RAD52). Interestingly, curcumin delays aging, probably through hormesis, of the wild-type strain BY4741.

Allylated Curcumin Analog CA6 Inhibits TrxR1 and Leads to ROS-Dependent Apoptotic Cell Death in Gastric Cancer Through Akt-FoxO3a

Background

Gastric cancer is one of the leading causes of cancer-related deaths. Allylated monocarbonyl analogs of curcumin (MACs) have been reported to selectively inhibit a broad range of human cancers including gastric cancer. However, the precise molecular mechanisms underlying the inhibitory activities of MACs are not fully known.

Methods

In this study, we examined the anti-tumor activities of an allylated MAC, CA6, on gastric cancer cells and gastric cancer xenograft mouse model. The potential molecular anti-tumor mechanisms of CA6 were also elucidated.

Results

Our data show that CA6 exhibited significant cytotoxicity in gastric cancer cells, which was seen as an induction of G2/M cell cycle arrest and apoptosis. These activities were mediated through an elaboration of ROS levels in gastric cancer cells and induction of endoplasmic reticulum stress. CA6 increased ROS levels through directly binding to and inhibiting thioredoxin reductase R1 (TrxR1). Also, CA6-generated ROS inhibited Akt and activated forkhead O3A (FoxO3a), causing cytotoxicity in gastric cancer cells. Finally, CA6 treatment dose-dependently reduced the growth of gastric cancer xenografts in tumor-bearing mice, which was associated with reduced TrxR1 activity and increased ROS in the tumor.

Conclusion

In summary, our studies demonstrate that CA6 inhibited gastric cancer growth by inhibiting TrxR1 and increasing ROS, which in turn activated FoxO3a through suppressing Akt. CA6 is a potential candidate for the treatment of gastric cancer.

Curcumin: From a controversial "panacea" to effective antineoplastic products

BACKGROUND

Curcumin, a controversial "panacea," has been broadly studied. Its bioactivities including antioxidant, anti-inflammatory, and especially antineoplastic activities have been documented. However, due to its extensive bioactivities, some scientists hold a skeptical point of view toward curcumin and described curcumin as a "deceiver" to chemists. The objective of this study was to explore curcumin's another possibility as a potential supplementary leading compound to cancer treatments.

METHODS

Literature searches were conducted using electronic databases. Search terms such as "curcumin," "curcumin analogues," and so on were used. The literatures were collected and summarized. In this article, reported targets of curcumin are reviewed. The limitations of a curcumin as a therapeutic anticancer product including low bioavailability and poor targeting are mentioned. Furthermore, modified curcumin analogues and antitumor mechanisms are listed and discussed in the aspects of cell death and tumor microenvironment including angiogenesis, tissue hypoxia status, and energy metabolism.

RESULTS

Several possible modification strategies were presented by analyzing the relationships between the antitumor activity of curcumin analogues and their structural characteristics, including the introduction of hydrophilic group, shortening of redundant hydrocarbon chain, the introduction of extra chemical group, and so on.

CONCLUSIONS

From our perspective, after structural modification curcumin could be more effective complementary product for cancer therapies by the enhancement of targeting abilities and the improvement of bioavailability.

Bioactive Compounds: Natural Defense Against Cancer?

Cancer is a devastating disease that has claimed many lives. Natural bioactive agents from plants are gaining wide attention for their anticancer activities. Several studies have found that natural plant-based bioactive compounds can enhance the efficacy of chemotherapy, and in some cases ameliorate some of the side-effects of drugs used as chemotherapeutic agents. In this paper, we have reviewed the literature on the anticancer effects of four plant-based bioactive compounds namely, curcumin, myricetin, geraniin and tocotrienols (T3) to provide an overview on some of the key findings that are related to this effect. The molecular mechanisms through which the active compounds may exert their anticancer properties in cell and animal-based studies also discussed.

Insights on the synthesis of asymmetric curcumin derivatives and their biological activities

Curcumin is a small organic molecule with pleiotropic biological activities. However, its multiple structural-pharmacokinetic challenges prevent its development into a clinical drug. Various structural modifications have been made to improve its drug profile. In this review, we focus on the methods adopted in the synthesis of asymmetric curcumin derivatives and their biological activities and forecast the future of this exciting class of compounds in the field of medicine.

Dual role of Endoplasmic Reticulum Stress-Mediated Unfolded Protein Response Signaling Pathway in Carcinogenesis

Cancer constitutes a grave problem nowadays in view of the fact that it has become one of the main causes of death worldwide. Poor clinical prognosis is presumably due to cancer cells metabolism as tumor microenvironment is affected by oxidative stress. This event triggers adequate cellular response and thereby creates appropriate conditions for further cancer progression. Endoplasmic reticulum (ER) stress occurs when the balance between an ability of the ER to fold and transfer proteins and the degradation of the misfolded ones become distorted. Since ER is an organelle relatively sensitive to oxidative damage, aforementioned conditions swiftly cause the activation of the unfolded protein response (UPR) signaling pathway. The output of the UPR, depending on numerous factors, may vary and switch between the pro-survival and the pro-apoptotic branch, and hence it displays opposing effects in deciding the fate of the cancer cell. The role of UPR-related proteins in tumorigenesis, such as binding the immunoglobulin protein (BiP) and inositol-requiring enzyme-1α (IRE1α), activating transcription factor 6 (ATF6) or the protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK), has already been specifically described so far. Nevertheless, due to the paradoxical outcomes of the UPR activation as well as gaps in current knowledge, it still needs to be further investigated. Herein we would like to elicit the actual link between neoplastic diseases and the UPR signaling pathway, considering its major branches and discussing its potential use in the development of a novel, anti-cancer, targeted therapy.

Arca subcrenata Polypeptides Inhibit Human Colorectal Cancer HT-29 Cells Growth via Suppression of IGF-1R/Akt/mTOR Signaling and ATP Production

Arca subcrenata Lischke, widely scattering offshore at neritic regions, is very popular on dining table due to its edible and medical functional meatball. This study aims to investigate the suppression of a polypeptide fraction from A. subcrenata (PAS) on human colorectal cancer HT-29 cells, and its underlying mechanism. The results showed that PAS inhibited the growth of HT-29 cells with an IC₅₀ value of 117 μg/ml after 48 h treatment, and significantly suppressed the tumor growth in nude mice bearing-xenografted HT-29 cells at the dosage of 63 mg/kg, with little influence on normal colon cells and normal colonic mucosa. PAS was then inspiringly found to induce apoptosis and G2/M phase arrest in HT-29 cells. The effect mechanism was involved in the inhibition of IGF-1/IGF-1R signaling activation, which was responsible for inactivating downstream Akt/mTOR pathway. Immunofluorescence assay also showed that PAS could reduce phosphorylation of IGF-1R (Tyr1165/1166). IGF-1, an IGF-1R activator, could reverse the suppression of PAS on IGF-1R phosphorylation. Furthermore, PAS significantly inhibited ATP production of HT-29 cells both in vitro and in vivo. Our results provide positive evidence that A. subcrenata has the potential to be a candidate for the treatment of colorectal cancer.

Curcumin induced oxidative stress causes autophagy and apoptosis in bovine leucocytes transformed by Theileria annulata

Bovine tropical theileriosis is a tick-borne disease, caused by Theileria annulata which is a protozoan parasite that resides within the B-cells and macrophages. T. annulata is a unique parasite that can transform bovine leucocytes which leads to the cancer hallmarks in the infected cells. Previously, curcumin has been shown to possess multiple pharmacological activities such as anti-inflammatory and anti-cancer activities. In this study, we demonstrated that curcumin inhibits the proliferation of Theileria-transformed bovine leucocytes by promoting apoptosis and autophagy. The transcriptome analysis of curcumin treated cells showed that the genes involved in cell death and autophagy are also differentially regulated. We further elucidated the mechanism of action of curcumin on Theileria infected bovine cells. We found that curcumin induced the generation of reactive oxygen species (ROS) which activated caspase 8 and destabilized the mitochondrial membrane potential leading to the release of cytochrome c from mitochondria. This subsequently led to the activation of caspase 3 and PARP cleavage, finally leading to apoptosis in the infected cells. Furthermore, curcumin induced the process of autophagy which was characterized by the formation of acidic vesicular organelles, LC3B accumulation with lysosome inhibitor, E64d, and the presence of autophagosomes as visualized by transmission electron microscopy (TEM). Curcumin treatment suppressed the mTOR and increased the expression of autophagy-related proteins. We also found that N- acetylcysteine, an inhibitor of ROS, could rescue the infected cells from curcumin induced apoptosis and autophagy mediated cell death. Intriguingly, curcumin had no effect on uninfected bovine PBMCs. Altogether, these data suggest the therapeutic potential of curcumin against bovine tropical theileriosis.

Developments in the anticancer activity of structurally modified curcumin: An up-to-date review

Curcumin is a pharmacologically active polyphenol derived from the popular spice element-Turmeric. The therapeutic activity of curcumin has been extensively investigated over the last few decades and reports suggest the role of curcumin in a large number of biological activities, particularly its prominent anticancer activity. Curcumin, being a pleiotropic molecule, is a regulator of multiple molecular targets which play crucial roles in various cell signaling pathways. It is known to suppress transformation, inhibit proliferation as well as induce apoptosis. However, despite all these benefits, the efficacy of curcumin remains limited due to its poor bioavailability, poor absorption within the systemic circulation and rapid elimination from the body. To overcome these limiting factors, researchers all around the world are working towards designing a synthetic and superior curcuminoid by making suitable structural modifications to the parent skeleton. These curcuminoids, mainly analogues and derivatives, will not only improve the physicochemical properties but also enhance the efficacy simultaneously. The present review will provide a comprehensive account of the analogues and derivatives of curcumin that have been reported since 2014 which have indicated a better anticancer activity than curcumin.

Sea Cucumber (Stichopus japonicas) F2 Enhanced TRAIL-Induced Apoptosis via XIAP Ubiquitination and ER Stress in Colorectal Cancer Cells

Natural products have shown great promise in sensitizing cells to TNF-related apoptosis-inducing ligand (TRAIL) therapy. Sea cucumber (SC) extracts possess antitumor activity, and hence their potential to sensitize colorectal cancer (CRC) cells to TRAIL therapy was evaluated. This study used Western blotting to evaluate the combination effects of SC and TRAIL in CRC, and determined the molecular mechanism underlying these effects. SC fractions and TRAIL alone did not affect apoptosis; however, combined treatment dramatically induced the apoptosis of CRC cells, but not of normal colon cells. Combined treatment induced the expression of apoptotic proteins (poly (ADP-ribose) polymerase (PARP), caspase 3, and 8), and this effect was markedly inhibited by the ubiquitination of X-linked inhibitor of apoptosis protein (XIAP). SC did not affect the mRNA levels, but it increased proteasomal degradation and ubiquitination of the XIAP protein. Furthermore, SC induced reactive oxygen species (ROS) production, thereby activating c-Jun N-terminal kinase (JNK) and endoplasmic reticulum (ER) stress-related apoptotic pathways in CRC. Altogether, our results demonstrate that the SC F2 fraction may sensitize CRC cells to TRAIL-induced apoptosis through XIAP ubiquitination and ER stress.

Bloom Syndrome Protein Activates AKT and PRAS40 in Prostate Cancer Cells

Purpose

Prostate cancer (PC) is a common malignant tumor and a leading cause of cancer-related death in men worldwide. In order to design new therapeutic interventions for PC, an understanding of the molecular events underlying PC tumorigenesis is required. Bloom syndrome protein (BLM) is a RecQ-like helicase, which helps maintain genetic stability. BLM dysfunction has been implicated in tumor development, most recently during PC tumorigenesis. However, the molecular basis for BLM-induced PC progression remains poorly characterized. In this study, we investigated whether BLM modulates the phosphorylation of an array of prooncogenic signaling pathways to promote PC progression.

Methods

We analyzed differentially expressed proteins (DEPs) using iTRAQ technology. Site-directed knockout of BLM in PC-3 prostate cancer cells was performed using CRISPR/Cas9-mediated homologous recombination gene editing to confirm the effects of BLM on DEPs. PathScan® Antibody Array Kits were used to analyze the phosphorylation of nodal proteins in PC tissue. Immunohistochemistry and automated western blot (WES) analyses were used to validate these findings.

Results

We found that silencing BLM in PC-3 cells significantly reduced their proliferative capacity. In addition, BLM downregulation significantly reduced levels of phosphorylated protein kinase B (AKT (Ser473)) and proline-rich AKT substrate of 40 kDa (PRAS40 (Thr246)), and this was accompanied by enhanced ROS (reactive oxygen species) levels. In addition, we found that AKT and PRAS40 inhibition reduced BLM, increased ROS levels, and induced PC cell apoptosis.

Conclusions

We demonstrated that BLM activates AKT and PRAS40 to promote PC cell proliferation and survival. We further propose that ROS act in concert with BLM to facilitate PC oncogenesis, potentially via further enhancing AKT signaling and downregulating PTEN expression. Importantly, inhibiting the BLM-AKT-PRAS40 axis induced PC cell apoptosis. Thus, we highlight new avenues for novel anti-PC treatments.

Curcumin inhibits the proliferation and invasion of MG-63 cells through inactivation of the p-JAK2/p-STAT3 pathway

Purpose

The aims of this study were to determine the effect of curcumin on osteosarcoma (OS) cells due to inactivation of the p-JAK2/p-STAT3 pathway and evaluate the prognostic value of this pathway in OS.

Materials and methods

We exposed a human OS cell line (MG-63) to different concentrations of curcumin. Then, we characterized the effects on MG-63 cells using assays (cell viability, colony formation, cell cycle, wound healing, invasion), flow cytometry, Western blot, immunohistochemical analyses, and tumor xenograft.

Results

The half-maximal inhibitory of curcumin for MG-63 cells at 24 hours was 27.6 µM. The number of colonies of MG-63 cells was decreased obviously upon curcumin (10 and 20 µM) treatment. We also found increased accumulation of MG-63 cells in the G2/M phase upon curcumin (10 and 20 µM) treatment. Apoptosis was increased in 10 and 20 µM curcumin-treated MG-63 cells. After incubation of physically wounded cells for 24 hours, the percentage wound width increased upon curcumin exposure. Curcumin obviously decreased the expression of pJAK-2 and pSTAT-3 in MG-63 cells in a dose-dependent manner. Curcumin dose-dependently inhibited the proliferation, migration, and invasion of MG-63 cells and induced arrest of the G0/G1 phase and apoptosis by inhibiting the p-JAK2/p-STAT3 pathway. The linear correlativity between expression of p-JAK2 and STAT3 was very prominent, and both were closely associated with lung metastasis. In vivo study suggested that curcumin suppressed tumor growth through JAK2/STAT3 signaling.

Conclusion

Curcumin-mediated inhibition of the proliferation and migration of MG-63 cells was associated with inactivation of JAK/STAT signaling.

Curcumin exerts cytotoxicity dependent on reactive oxygen species accumulation in non-small-cell lung cancer cells

AIM

Curcumin induces cytotoxic cell death in several human cancer cells. Here, we have investigated the effects of curcumin on non-small-cell lung cancer (NSCLC) with an aim to identify underlying mechanisms of its cytotoxic effect.

MATERIALS & METHODS

The effects of various concentrations of curcumin on the NSCLC cell lines A549 and SPC-A1 were evaluated by MTT assay, colony-forming assay and flow cytometry. Additionally, protein expression associated with different signaling pathways was assessed using western blotting.

RESULTS

Curcumin exhibited cytotoxicity against NSCLC, evident from the inhibition of cell proliferation, G2/M arrest, DNA damage, endoplasmic reticulum stress and mitochondrial apoptosis. The anticancer effect was related to reactive oxygen species (ROS) accumulation and could be reversed by ROS scavengers, catalase and N-acetyl-l-cysteine. Curcumin decreased mitochondrial transmembrane potential and induced ROS production, thereby activating the DNA damage/repair pathway and mitochondrial apoptosis.

CONCLUSION

These results indicate that curcumin could be an effective therapeutic candidate for NSCLC.

Dibenzoylmethane ameliorates lipid-induced inflammation and oxidative injury in diabetic nephropathy

Dibenzoylmethane (DBM) is a beta-diketone analog of curcumin. Numerous studies have shown the beneficial effects of curcumin on diabetes, obesity and diabetic complications including diabetic nephropathy. Recently, we investigated the beneficial metabolic effects of DBM on high-fat diet-induced obesity. However, the effects and mechanisms of action of DBM in the kidney are currently unknown. To investigate the renoprotective effects of DBM in type 2 diabetes, we administered DBM (100 mg/kg) orally for 12 weeks to high-fat diet-induced diabetic model mice. We used mouse renal mesangial (MES13) and macrophage (RAW 264.7) cells to examine the mechanism of action of DBM (20 μM). After DBM treatment, the albumin-to-creatinine ratio was significantly decreased compared to that of the high-fat-diet group. Moreover, damaged renal ultra-structures and functions including increased glomerular volume, glomerular basement membrane thickness and inflammatory signals were ameliorated after DBM treatment. Stimulation of MES13 and RAW264.7 cells by palmitate or high-dose glucose with lipopolysaccharides increased inflammatory signals and macrophage migration. However, these changes were reversed by DBM treatment. In addition, DBM inhibited NADPH oxidase 2 and 4 expression and oxidative DNA damage. Collectively, these data suggested that DBM prevented diabetes-induced renal injury through its anti-inflammatory and antioxidant effects.

A curcumin derivative, WZ35, suppresses hepatocellular cancer cell growthviadownregulating YAP-mediated autophagy

HCC is a common cancer type in the world. Here, we found WZ35, a novel derivative of curcumin, could notably suppress HCC cell growthviainhibiting YAP controlled autophagy, highlighting the potent anti-tumor activity of WZ35 in liver cancer therapy.

Glutathione reductase-mediated thiol oxidative stress suppresses metastasis of murine melanoma cells

Malignant melanoma is a highly metastatic and life-threatening cancer. Reactive oxygen species (ROS) play important roles in cancer initiation and progression including metastasis. It has been reported that the oxidative stress spontaneously generated in circulating melanoma cells was able to suppress distant metastasis in vivo. However, little is known regarding the effects and mechanism of glutathione reductase (GR) inhibition-induced oxidative stress in regulation of melanoma metastasis. Here, we demonstrate that GR inhibition generates oxidative stress and suppresses lung metastasis and subcutaneous growth of melanoma in vivo. In addition, inhibitory effects by GR activity reduction were observed on cell proliferation, colony formation, cell adhesion, migration and invasion in melanoma cells in vitro. GR inhibition-induced oxidative stress was also found to block epithelial-to-mesenchymal transition (EMT) by decreasing the expression of Vimentin, ERK1/2, transcription factor Snail and increasing the expression of E-cadherin. In addition, actin rearrangement, a key element involved in cell motility, was also affected by GR-mediated oxidative stress possibly through protein S-glutathionylation on actin. In conclusion, this study identifies GR as an effective regulator of oxidative stress that affects the multistep processes of metastasis in melanoma cells, and it becomes a potential target for melanoma therapy.

Isobavachalcone Induces ROS-Mediated Apoptosis via Targeting Thioredoxin Reductase 1 in Human Prostate Cancer PC-3 Cells

Prostate carcinoma causes a great number of deaths every year; therefore, there is an urgent need to find new drug candidates to treat advanced prostate cancer. Isobavachalcone (IBC) is the chalcone composition of Psoralea corylifolia Linn used in traditional Chinese medicine. Although IBC demonstrates potent anticancer efficacy in numerous types of human cancer cells, the cellular targets of IBC have not been fully defined. In our study, we found that IBC may induce reactive oxygen species- (ROS-) mediated apoptosis via interaction with a selenocysteine (Sec) containing the antioxidant enzyme thioredoxin reductase 1 (TrxR1), and induce lethal endoplasmic reticulum (ER) stress by inhibiting TrxR1 activity and increasing ROS levels in human prostate cancer PC-3 cells. Furthermore, we also observed that knocking down TrxR1 would sensitized cancer cells to IBC treatment. Our study provides evidence for the anticancer mechanism of IBC with TrxR1 as a potential target.

The curcumin derivative WZ35 activates ROS-dependent JNK to suppress hepatocellular carcinoma metastasis

Tumor metastasis is the leading cause of cancer death; due to the progress made in the elucidation of the mechanism of cancer cell metastasis, there is hope for patients with severe stages of cancer. Curcumin, as a novel anti-cancer drug, has been applied in cancer therapy; however, the toxicity of curcumin hinders its application. Herein, we constructed a novel derivative, WZ35, and evaluated its metastatic inhibition properties in vitro and in vivo. CCK-8 assay was performed to evaluate the tumor suppressive activity of WZ35. Cell apoptosis was detected by flow cytometry analysis. Transwell cell migration assay and RTCA were used to detect cell migration in mock and WZ35-treated cells. Western blotting was performed to analyze molecular alteration with different treatments. In this study, we found that curcumin and its derivative WZ35 could dramatically suppress proliferation, invasion, and migration of the hepatocellular HCCLM3, HepG2, and Huh7 cancer cells. Moreover, the cancer cell metastatic markers MMP-2, MMP-9, and N-cadherin were decreased, and E-cadherin was up-regulated. In addition, our data show that WZ35 promotes ROS-dependent JNK activation that is essential for WZ35-caused cell metastasis suppression. Moreover, the NAC and JNK inhibitor SP600125 could dramatically reverse WZ35-caused MMP-2, MMP-9, and N-cadherin reduction and E-cadherin up-regulation. We have also found that WZ35 exhibits powerful anti-metastasis activity of HCCLM3 in vivo. In conclusion, our data indicated that WZ35 could be a candidate for the treatment of metastatic liver cancer patients.

A mono-carbonyl analog of curcumin induces apoptosis in drug-resistant EGFR-mutant lung cancer through the generation of oxidative stress and mitochondrial dysfunction

Introduction

Targeted therapies using epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) have revolutionized the treatment of non-small cell lung cancer (NSCLC) patients harboring EGFR mutations, leading to the approval of gefitinib and erlotinib as standard first-line clinical treatment. Inevitably, a considerable proportion of patients develop resistance to EGFR-TKIs due to the acquisition of secondary mutations within EGFR. Therefore, alternative strategies to target NSCLC are desperately needed.

Materials and methods

In this study, we have evaluated the effect of a reactive oxygen species (ROS)-inducing agent WZ35, a mono-carbonyl analog of curcumin, to target an inherent biological property of cancer cells, increased oxidative stress. To study whether WZ35 can inhibit NSCLC tumorigenesis, we used gefitinib- and erlotinib-resistant cell line H1975.

Results

In this study, we show that WZ35 treatment dramatically decreases cell viability and induces apoptosis in H1975 cells through the generation of ROS. We also found that the antitumor activity of WZ35 involved ROS-mediated activation of the endoplasmic reticulum stress pathway and mitochondrial dysfunction. Furthermore, WZ35 significantly inhibited H1975 xenograft tumor growth through the inhibition of cell proliferation and induction of apoptosis.

Discussion

These findings show that WZ35 may be a promising candidate for the treatment of EGFR-TKI-resistant NSCLC.

Asymmetrical meta-methoxylated diarylpentanoids: Rational design, synthesis and anti-cancer evaluation in-vitro

In the present study, a series of forty-five asymmetrical meta-methoxylated diarylpentanoids have been synthesized, characterized and evaluated for their in-vitro anti-cancer potential. Among the forty-five analogs, three compounds (20, 33 and 42) have been identified as lead compounds due to their excellent inhibition against five human cancer cell lines including SW620, A549, EJ28, HT1080 and MCF-7. Structure-activity relationship study on cytotoxicity of tested compounds suggested that the presence of meta-oxygenated phenyl ring played a critical role in enhancing their cytotoxic effects. Compounds 33 and 42 in particular, exhibited strongest cytotoxicity against tested cell lines with the IC₅₀ values ranging from 1.1 to 4.3 μM. Subsequent colony formation assay on SW620 cell line showed that both compounds 33 and 42 possessed strong anti-proliferative activity. In addition, flow cytometry based experiments revealed that these compounds could trigger intracellular ROS production thus inducing G2/M-phase cell arrest and apoptosis. All these results suggested that poly meta-oxygenated diarylpentnoid is a promising scaffold which deserved further modification and investigation in the development of natural product-based anti-cancer drug.

Oxidative Stress Mediates Microcystin-LR-Induced Endoplasmic Reticulum Stress and Autophagy in KK-1 Cells and C57BL/6 Mice Ovaries

Microcystin-leucine arginine (MC-LR) is a cyclic heptapeptide intracellular toxin released by cyanobacteria that exhibits strong reproductive toxicity. However, little is known about its biotoxicity to the female reproductive system. The present study investigates unexplored molecular pathways by which oxidative stress acts on MC-LR-induced endoplasmic reticulum stress (ERs) and autophagy. In the present study, immortalized murine ovarian granular cells (KK-1 cells) were exposed to 8.5, 17, and 34 μg/mL (IC₅₀) of MC-LR with or without N-acetyl-l-cysteine (NAC, 10 mM) for 24 h, and C57BL/6 mice were treated with 12.5, 25.0, and 40.0 μg/kg⋅bw of MC-LR with or without NAC (200 mg/kg⋅bw) for 14 days. The results revealed that MC-LR could induce cells apoptosis and morphologic changes in ovarian tissues, induce oxidative stress by stimulating the generation of reactive oxygen species (ROS), destroying antioxidant capacity, and subsequently trigger ERs and autophagy by inducing the hyper-expression of ATG12, ATG5, ATG16, EIF2α (phosphorylated at S51), CHOP, XBP1, GRP78, Beclin1, and PERK (Thr980). Furthermore, NAC pretreatment partly inhibited MC-LR-induced ERs and autophagy via the PERK/ATG12 and XBP1/Beclin1 pathways. These results suggest that oxidative stress mediated MC-LR-induced ERs and autophagy in KK-1 cells and C57BL/6 mice ovaries. Therefore, oxidative stress plays an important role in female toxicity induced by MC-LR.

Synthesis of Novel Aza-aromatic Curcuminoids with Improved Biological Activities towards Various Cancer Cell Lines

Curcumin, a natural compound extracted from the rhizomes of Curcuma longa, displays pronounced anticancer properties but lacks good bioavailability and stability. In a previous study, we initiated structure modification of the curcumin scaffold by imination of the labile β-diketone moiety to produce novel β-enaminone derivatives. These compounds showed promising properties for elaborate follow-up studies. In this work, we focused on another class of nitrogen-containing curcuminoids with a similar objective: to address the bioavailability and stability issues and to improve the biological activity of curcumin. This paper thus reports on the synthesis of new pyridine-, indole-, and pyrrole-based curcumin analogues (aza-aromatic curcuminoids) and discusses their water solubility, antioxidant activity, and antiproliferative properties. In addition, multivariate statistics, including hierarchical clustering analysis and principal component analysis, were performed on a broad set of nitrogen-containing curcuminoids. Compared to their respective mother structures, that is, curcumin and bisdemethoxycurcumin, all compounds, and especially the pyridin-3-yl β-enaminone analogues, showed better water solubility profiles. Interestingly, the pyridine-, indole-, and pyrrole-based curcumin derivatives demonstrated improved biological effects in terms of mitochondrial activity impairment and protein content, in addition to comparable or decreased antioxidant properties. Overall, the biologically active N-alkyl β-enaminone aza-aromatic curcuminoids were shown to offer a desirable balance between good solubility and significant bioactivity.

Curcumin enhances the effects of irinotecan on colorectal cancer cells through the generation of reactive oxygen species and activation of the endoplasmic reticulum stress pathway

Although initially effective against metastatic colorectal cancer (CRC), irinotecan-based chemotherapy leads to resistance and adverse toxicity. Curcumin is well known for its anti-cancer effects in many cancers, including CRC. Here, we describe reactive oxygen species (ROS) generation and endoplasmic reticulum (ER) stress as important mechanisms by which curcumin enhances irinotecan's effects on CRC cells. CRC cell lines were treated with curcumin and/or irinotecan for 24 h, and then evaluated using cell proliferation assays, cell apoptosis assays, cell cycle analysis, intracellular Ca²⁺ measurements, ROS measurements and immunoblotting for key ER stress-related proteins. We found that cell viability was inhibited and apoptosis was increased, accompanied by ROS generation and ER stress activation in CRC cells treated with curcumin alone or in combination with irinotecan. Blocking ROS production attenuated the expression of two markers of ER stress: binding of immunoglobulin protein (BIP) and CCAAT/enhancer-binding protein homologous protein (CHOP). Blocking CHOP expression using RNA interference also inhibited ROS generation. These results demonstrated that curcumin could enhance the effects of irinotecan on CRC cells by inhibiting cell viability and inducing cell cycle arrest and apoptosis, and that these effects may be mediated, in part, by ROS generation and activation of the ER stress pathway.

Cytoplasmic vacuolization in cell death and survival

Cytoplasmic vacuolization (also called cytoplasmic vacuolation) is a well-known morphological phenomenon observed in mammalian cells after exposure to bacterial or viral pathogens as well as to various natural and artificial low-molecular-weight compounds. Vacuolization often accompanies cell death; however, its role in cell death processes remains unclear. This can be attributed to studying vacuolization at the level of morphology for many years. At the same time, new data on the molecular mechanisms of the vacuole formation and structure have become available. In addition, numerous examples of the association between vacuolization and previously unknown cell death types have been reported. Here, we review these data to make a deeper insight into the role of cytoplasmic vacuolization in cell death and survival.

Curcumol induces cell cycle arrest in colon cancer cells via reactive oxygen species and Akt/ GSK3β/cyclin D1 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Curcuma kwangsiensis S. G. Lee & C. F. Liang (Guangxi ezhu, in Chinese) belongs to the Zingiberaceae family, has been used as a traditionally Chinese medicine nearly 2000 year. Curcumol is one of the guaiane-type sesquiterpenoid hemiketal isolated from medicine plant Curcuma kwangsiensis S. G. Lee & C. F. Liang, which has been reported possesses anti-cancer effects. Our previous study found that the most contribution to inhibit nasopharyngeal carcinoma cell growth was curcumol.

AIM OF THE STUDY

To assess the effect of curcumol on cell cycle arrest against human colon cancer cells (CRC) cells (LoVo and SW480) and explore its mechanism in vitro and in vivo.

MATERIALS AND METHODS

Curcumol was dissolved in absolute ethyl alcohol. The concentration of absolute ethyl alcohol in the control group or in experimental samples was always 1/500 (v/v) of the final medium volume. LoVo and SW480 cells were treated with different concentrations of curcumol (0, 53, 106, 212 and 424μM). And then the cell cycle of each group was examined by flow cytometry. The protein levels of PI3K, p-Akt, cyclin D1, cyclin E, CDK2, CDK4 and GSK3β were determined by Western blot. The mRNA expression of PI3K, Akt, cyclin D1, CDK4, P27, p21, and P16 in the treated cells were analyzed by real-time RT-PCR. In addition, the antitumor activity of curcumol was evaluated in nude mice bearing orthotopic tumor implants.

RESULTS

Curcumol induced cell cycle arrest in G1/S phase. RT-qPCR and Western blot data showed that curcumol enhanced the expression of GSK3β, P27, p21 and P16, and decreased the levels of PI3K, phosphorylated Akt (p-Akt), cyclin D1, CDK4, cyclin E and CDK2. Furthermore, curcumol induced reactive oxygen species (ROS) generation in LoVo cells, and ROS scavenger N-acetylcysteine (NAC) significantly reversed curcumol-induced cell growth inhibition. Besides, curcumol also prevented the growth of human colon cancer cells xenografts in nude mouse, accompanied by the reduction of PI3K, Akt, cyclin D1, CDK4, cycln E and significant increase of GSK3β.

CONCLUSIONS

Curcumol caused cell cycle arrest at the G0/G1 phase by ROS production and Akt/ GSK3β/cyclin D1 pathways inactivation, indicating the potential of curcumol in the prevention of colon cancer carcinogenesis.

IMMUNEPOTENT CRP induces cell cycle arrest and caspase-independent regulated cell death in HeLa cells through reactive oxygen species production

BACKGROUND

Regulated cell death (RCD) is a mechanism by which the cell activates its own machinery to self-destruct. RCD is important for the maintenance of tissue homeostasis and its deregulation is involved in diseases such as cervical cancer. IMMUNEPOTENT CRP (I-CRP) is a dialyzable bovine leukocyte extract that contains transfer factors and acts as an immunomodulator, and can be cytotoxic to cancer cell lines and reduce tumor burden in vivo. Although I-CRP has shown to improve or modulate immune response in inflammation, infectious diseases and cancer, its widespread use has been limited by the absence of conclusive data on the molecular mechanism of its action.

METHODS

In this study we analyzed the mechanism by which I-CRP induces cytotoxicity in HeLa cells. We assessed cell viability, cell death, cell cycle, nuclear morphology and DNA integrity, caspase dependence and activity, mitochondrial membrane potential, and reactive oxygen species production.

RESULTS

I-CRP diminishes cell viability in HeLa cells through a RCD pathway and induces cell cycle arrest in the G2/M phase. We show that the I-CRP induces caspase activation but cell death induction is independent of caspases, as observed by the use of a pan-caspase inhibitor, which blocked caspase activity but not cell death. Moreover, we show that I-CRP induces DNA alterations, loss of mitochondrial membrane potential, and production of reactive-oxygen species. Finally, pretreatment with N-acetyl-L-cysteine (NAC), a ROS scavenger, prevented both ROS generation and cell death induced by I-CRP.

CONCLUSIONS

Our data indicate that I-CRP treatment induced cell cycle arrest in G2/M phase, mitochondrial damage, and ROS-mediated caspase-independent cell death in HeLa cells. This work opens the way to the elucidation of a more detailed cell death pathway that could potentially work in conjunction with caspase-dependent cell death induced by classical chemotherapies.

Anticancer potential of novel curcumin analogs towards castrate-resistant prostate cancer

Prostate cancer is initially sensitive to hormone therapy; however, over time the majority of patients progress to a hormone-insensitive form classified as castration-resistant prostate cancer (CRPC). CRPC is highly metastatic and patients have a poor prognosis. Thus, new drugs for the treatment of this disease are required. In this study, we therefore examined the cytotoxic effects and anticancer mechanism(s) of action of second generation curcumin analogs towards CRPC cells. For this purpose, PC3 and DU145 cells were treated with a series of curcumin analogs at 0-10 µM for 72 h and cytotoxicity was determined by the sulforhodamine B (SRB) assay. Two compounds, 1-isopropyl-3,5-bis(pyridin-3-ylmethylene)-4-piperidone (RL118) and 1-methyl-3,5-[(6-methoxynaphthalen-2-yl)methylene]-4-piperidone (RL121), were found to have the most potent cytotoxic effect with EC50 values of 0.50 and 0.58 µM in the PC3 cells and EC50 values of 0.76 and 0.69 µM in the DU145 cells, respectively. Thus, further experiments were performed focusing on these two compounds. Flow cytometry was performed to determine their effects on the cell cycle and apoptosis. Both analogs increased the number of cells in the G2/M phase of the cell cycle and induced apoptosis. Specifically, in the PC3 cells, RL121 increased the number of cells in the G2/M phase by 86% compared to the control, while RL118 increased the number of cells in the G2/M phase by 42% compared to the control after 24 h. Moreover, both RL118 and RL121 induced the apoptosis of both cell lines. In the DU145 cells, a 38-fold increase in the number of apoptotic cells was elicited by RL118 and a 78-fold increase by RL121 compared to the control. Furthermore, the effects of both analogs on the expression of key proteins involved in cell proliferation were also determined by western blot analysis. The results revealed that both analogs inhibited the expression of nuclear factor (NF)-κB (p65/RelA), eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1), p-4E-BP1, mammalian target of rapamycin (mTOR), p-mTOR, AKT and p-AKT. Thus, the findings of this study provide evidence that RL118 and RL121 have potent anticancer activity against CPRC cells, and both analogs warrant further investigation in vivo.

PDGF signaling pathway in hepatic fibrosis pathogenesis and therapeutics (Review)

The platelet‑derived growth factor (PDFG) signaling pathway exerts persistent activation in response to a variety of stimuli and facilitates the progression of hepatic fibrosis. Since this pathway modulates a broad spectrum of cellular processes, including cell growth, differentiation, inflammation and carcinogenesis, it has emerged as a therapeutic target for hepatic fibrosis and liver‑associated disorders. The present review exhibits the current knowledge of the role of the PDGF signaling pathway and its pathological profiles in hepatic fibrosis, and assesses the potential of inhibitors which have been investigated in the experimental hepatic fibrosis model, in addition to the clinical challenges associated with these inhibitors.