Pristimerin effectively inhibits the malignant phenotypes of uveal melanoma cells by targeting NF‑κB pathway

Cancer stem-like cells in uveal melanoma: novel insights and therapeutic implications

Uveal melanoma (UM) is the most common primary ocular tumor in the adult population. Even though these primary tumors are successfully treated in 90% of cases, almost 50% of patients ultimately develop metastasis, mainly in the liver, via hematological dissemination, with a median survival spanning from 6 to 12 months after diagnosis. In this context, chemotherapy regimens and molecular targeted therapies have demonstrated poor response rates and failed to improve survival. Among the multiple reasons for therapy failure, the presence of cancer stem-like cells (CSCs) represents the main cause of resistance to anticancer therapies. In the last few years, the existence of CSCs in UM has been demonstrated both in preclinical and clinical studies, and new molecular pathways and mechanisms have been described for this subpopulation of UM cells. Here, we will discuss the state of the art of CSC biology and their potential exploitation as therapeutic target in UM.

Anticancer Potential and Molecular Targets of Pristimerin in Human Malignancies

The growing global burden of malignant tumors with increasing incidence and mortality rates underscores the urgent need for more effective and less toxic therapeutic options. Herbal compounds are being increasingly studied for their potential to meet these needs due to their reduced side effects and significant efficacy. Pristimerin (PS), a triterpenoid from the quinone formamide class derived from the Celastraceae and Hippocrateaceae families, has emerged as a potent anticancer agent. It exhibits broad-spectrum anti-tumor activity across various cancers such as breast, pancreatic, prostate, glioblastoma, colorectal, cervical, and lung cancers. PS modulates several key cellular processes, including apoptosis, autophagy, cell migration and invasion, angiogenesis, and resistance to chemotherapy, targeting crucial signaling pathways such as those involving NF-κB, p53, and STAT3, among others. The main objective of this review is to provide a comprehensive synthesis of the current literature on PS, emphasizing its mechanisms of action and molecular targets with the utmost clarity. It discusses the comparative advantages of PS over current cancer therapies and explores the implications for future research and clinical applications. By delineating the specific pathways and targets affected by PS, this review seeks to offer valuable insights and directions for future research in this field. The information gathered in this review could pave the way for the successful development of PS into a clinically applicable anticancer therapy.

Signaling pathways driving ocular malignancies and their targeting by bioactive phytochemicals

Ocular cancers represent a rare pathology. The American Cancer Society estimates that 3,360 cases of ocular cancer occur annually in the United States. The major types of cancers of the eye include ocular melanoma (also known as uveal melanoma), ocular lymphoma, retinoblastoma, and squamous cell carcinoma. While uveal melanoma is one of the primary intraocular cancers with the highest occurrence in adults, retinoblastoma remains the most common primary intraocular cancer in children, and squamous cell carcinoma presents as the most common conjunctival cancer. The pathophysiology of these diseases involves specific cell signaling pathways. Oncogene mutations, tumor suppressor mutations, chromosome deletions/translocations and altered proteins are all described as causal events in developing ocular cancer. Without proper identification and treatment of these cancers, vision loss, cancer spread, and even death can occur. The current treatments for these cancers involve enucleation, radiation, excision, laser treatment, cryotherapy, immunotherapy, and chemotherapy. These treatments present a significant burden to the patient that includes a possible loss of vision and a myriad of side effects. Therefore, alternatives to traditional therapy are urgently needed. Intercepting the signaling pathways for these cancers with the use of naturally occurring phytochemicals could be a way to relieve both cancer burden and perhaps even prevent cancer occurrence. This research aims to present a comprehensive review of the signaling pathways involved in various ocular cancers, discuss current therapeutic options, and examine the potential of bioactive phytocompounds in the prevention and targeted treatment of ocular neoplasms. The current limitations, challenges, pitfalls, and future research directions are also discussed.

The multifaceted mechanisms of pristimerin in the treatment of tumors state-of-the-art

As a globally complicated disease, malignant tumor has long been posing a threat to human health with increasingly high morbidity and mortality. Notably, existing treatments for tumors like chemotherapy generally carry intolerable toxicity, necessitating novel agents balancing safety and potency. Among them, the anti-tumor potency of herbs, featuring few adverse effects and promising efficacy, has attracted much attention recently. Pristimerin, a Quinone formamide triterpenoid compound extracted from Celastraceae and Portulacaceae, carries pronounced anti-tumor activity. It applies to various malignant tumors, including breast cancer, bile duct cancer, gastric cancer, pancreatic cancer, prostate cancer, glioblastoma, colorectal cancer, oral squamous cell carcinoma, cervical cancer, and lung cancer. In state-of-the-art understanding, pristimerin, alone or combined, can inhibit tumor cell proliferation, induce tumor cell apoptosis, inhibit tumor migration and invasion, inhibit angiogenesis, induce tumor cell autophagy, regulate the occurrence of inflammation related tumors, enhance chemosensitivity and regulate tumor microenvironment and immune cells. Despite the abundance of pristimerin-based research, systematic reviews on its anti-tumor mechanism remain needed. This study presented the anti-tumor mechanism of pristimerin by literature review, which might serve as a reference for further research and clinical practice.

Pristimerin alleviates cigarette smoke-induced inflammation in chronic obstructive pulmonary disease via inhibiting NF-κB pathway

Cigarette smoke (CS) is a risk factor for chronic obstructive pulmonary disease (COPD), which can exacerbate inflammation and oxidative stress. Pristimerin (Pris) is a natural compound with antioxidant and anti-inflammatory effects. We managed to evaluate the protective effects of Pris on CS-induced COPD. The CS-induced COPD mice model and cell model were constructed. The effects of Pris treatment on lung function, inflammatory cell infiltration, myeloperoxidase (MPO), and pathological changes of lung tissues in mice model were evaluated. The impacts of Pris treatment on inflammatory factors, chemokines, and oxidative stress parameters in mice lung tissues and cells were determined by kits. The viability of human bronchial epithelial cells after Pris treatment was tested by CCK-8. The activation of NF-κB pathway was confirmed by Western blot and immunofluorescence. CS treatment impaired lung function, reduced weight of mice, and enhanced inflammatory cell infiltration, MPO, and lung tissue damage, but these effects of CS were reversed by Pris treatment. Furthermore, Pris treatment downregulated the levels of malondialdehyde, IL-6, IL-1β, TNF-α, CXCL1, and CXLC2, but upregulated superoxide dismutase and catalase levels. Pris treatment could overturn CS-induced activation of the NF-κB pathway. Pris alleviates CS-induced COPD by inactivating NF-κB pathway.

The Interplay between Tumour Microenvironment Components in Malignant Melanoma

Malignant melanoma has shown an increasing incidence during the last two decades, exhibiting a large spectrum of locations and clinicopathological characteristics. Although current histopathological, biochemical, immunohistochemical, and molecular methods provide a deep insight into its biological behaviour and outcome, melanoma is still an unpredictable disease, with poor outcome. This review of the literature is aimed at updating the knowledge regarding melanoma’s clinicopathological and molecular hallmarks, including its heterogeneity and plasticity, involving cancer stem cells population. A special focus is given on the interplay between different cellular components and their secretion products in melanoma, considering its contribution to tumour progression, invasion, metastasis, recurrences, and resistance to classical therapy. Furthermore, the influences of the specific tumour microenvironment or “inflammasome”, its association with adipose tissue products, including the release of “extracellular vesicles”, and distinct microbiota are currently studied, considering their influences on diagnosis and prognosis. An insight into melanoma’s particular features may reveal new molecular pathways which may be exploited in order to develop innovative therapeutic approaches or tailored therapy.

Role of the AMPK signalling pathway in the aetiopathogenesis of ocular diseases

BACKGROUND

AMP-activated protein kinase (AMPK) plays a precise role as a master regulator of cellular energy homeostasis. AMPK is activated in response to the signalling cues that exhaust cellular ATP levels such as hypoxia, ischaemia, glucose depletion and heat shock. As a central regulator of both lipid and glucose metabolism, AMPK is considered to be a potential therapeutic target for the treatment of various diseases, including eye disorders.

OBJECTIVE

To review all the shreds of evidence concerning the role of the AMPK signalling pathway in the pathogenesis of ocular diseases.

METHOD

Scientific data search and review of available information evaluating the influence of AMPK signalling on ocular diseases.

RESULTS

Review highlights the significance of AMPK signalling in the aetiopathogenesis of ocular diseases, including cataract, glaucoma, diabetic retinopathy, retinoblastoma, age-related macular degeneration, corneal diseases, etc. The review also provides the information on the AMPK-associated pathways with reference to ocular disease, which includes mitochondrial biogenesis, autophagy and regulation of inflammatory response.

CONCLUSION

The study concludes the role of AMPK in ocular diseases. There is growing interest in the therapeutic utilization of the AMPK pathway for ocular disease treatment. Furthermore, inhibition of AMPK signalling might represent more pertinent strategy than AMPK activation for ocular disease treatment. Such information will guide the development of more effective AMPK modulators for ocular diseases.[Formula: see text].

Pristimerin induces apoptosis and tumor inhibition of oral squamous cell carcinoma through activating ROS-dependent ER stress/Noxa pathway

BACKGROUND

Pristimerin (Pri), a natural quinone methide triterpenoid isolated from Celastraceae and Hippocrateaceae, exhibits potent antitumor activity against various cancers. However, the mechanism of apoptosis induction by Pri in oral squamous cell carcinoma (OSCC) and its anti-OSCC effect in vivo has not been widely studied.

PURPOSE

This study aimed to investigate the anti-OSCC activities of Pri in vitro and in vivo and addressed the potential mechanisms of Pri-induced apoptosis.

METHODS

The effects of Pri on OSCC cells were analyzed by cell viability, colony formation and flow cytometry assays. Western blotting and qRT-PCR assays were chosen to detect the expression of proteins and genes. The anti-OSCC efficacy of Pri in vivo was evaluated by CAL-27 xenografts.

RESULTS

We showed that Pri inhibited the proliferation of human OSCC cell lines. Additionally, Pri induced apoptosis by upregulating Noxa expression. Furthermore, Pri treatment triggered excessive endoplasmic reticulum (ER) stress activation and subsequently induced c-Jun N-terminal kinase (JNK) signaling. ROS scavengers and ER stress inhibitors significantly attenuated Pri-induced OSCC cell apoptosis. Finally, Pri suppressed tumor growth in CAL-27 xenografts, accompanied ER stress activation and cell apoptosis.

CONCLUSION

These results reveal that Pri suppressed tumor growth and triggered cell apoptosis through ER stress activation in OSCC cells and xenografts, suggesting that Pri may serve as a therapeutic agent for OSCC.

Cellular and Molecular Mechanisms of Pristimerin in Cancer Therapy: Recent Advances

Seeking an efficient and safe approach to eliminate tumors is a common goal of medical fields. Over these years, traditional Chinese medicine has attracted growing attention in cancer treatment due to its long history. Pristimerin is a naturally occurring quinone methide triterpenoid used in traditional Chinese medicine to treat various cancers. Recent studies have identified alterations in cellular events and molecular signaling targets of cancer cells under pristimerin treatment. Pristimerin induces cell cycle arrest, apoptosis, and autophagy to exhibit anti-proliferation effects against tumors. Pristimerin also inhibits the invasion, migration, and metastasis of tumor cells via affecting cell adhesion, cytoskeleton, epithelial-mesenchymal transition, cancer stem cells, and angiogenesis. Molecular factors and pathways are associated with the anti-cancer activities of pristimerin. Furthermore, pristimerin reverses multidrug resistance of cancer cells and exerts synergizing effects with other chemotherapeutic drugs. This review aims to discuss the anti-cancer potentials of pristimerin, emphasizing multi-targeted biological and molecular regulations in cancers. Further investigations and clinical trials are warranted to understand the advantages and disadvantages of pristimerin treatment much better.

Pristimerin-induced uveal melanoma cell death via inhibiting PI3K/Akt/FoxO3a signalling pathway

Uveal melanoma (UM) is a highly invasive intraocular malignancy with high mortality. Presently, there is no FDA‐approved standard for the treatment of metastatic UM. Pristimerin is a natural quinine methide triterpenoid compound with anti‐angiogenic, anti‐cancer and anti‐inflammatory activities. However, Pristimerin potential cytotoxic effect on UM was poorly investigated. In the present study, we found the migration and invasion of UM‐1 cells were inhibited by Pristimerin which also caused a rapid increase of ROS, decreased mitochondrial membrane potential, induced the accumulation of cells in G0/G1 phase, ending with apoptotic cell death. Pristimerin inhibited Akt and FoxO3a phosphorylation and induced nuclear accumulation of FoxO3a in UM‐1 cells, increased the expression of pro‐apoptotic proteins Bim、p27^Kip1, cleaved caspase‐3, PARP and Bax, and decreased the expression of Cyclin D1 and Bcl‐2. LY294002 or Akt‐siRNA inhibited the PI3K/Akt/FoxO3a pathway and promoted the Pristimerin‐induced apoptosis, while Pristimerin effects were partially abolished in FoxO3a knockdown UM‐1 cell cultures. Taken together, present results showed that Pristimerin induced apoptotic cell death through inhibition of PI3K/Akt/FoxO3a pathway in UM‐1 cells. These findings indicate that Pristimerin may be considered as a potential chemotherapeutic agent for patients with UM.

Terpenoids, Cannabimimetic Ligands, beyond the Cannabis Plant

Medicinal use of Cannabis sativa L. has an extensive history and it was essential in the discovery of phytocannabinoids, including the Cannabis major psychoactive compound—Δ9-tetrahydrocannabinol (Δ9-THC)—as well as the G-protein-coupled cannabinoid receptors (CBR), named cannabinoid receptor type-1 (CB1R) and cannabinoid receptor type-2 (CB2R), both part of the now known endocannabinoid system (ECS). Cannabinoids is a vast term that defines several compounds that have been characterized in three categories: (i) endogenous, (ii) synthetic, and (iii) phytocannabinoids, and are able to modulate the CBR and ECS. Particularly, phytocannabinoids are natural terpenoids or phenolic compounds derived from Cannabis sativa. However, these terpenoids and phenolic compounds can also be derived from other plants (non-cannabinoids) and still induce cannabinoid-like properties. Cannabimimetic ligands, beyond the Cannabis plant, can act as CBR agonists or antagonists, or ECS enzyme inhibitors, besides being able of playing a role in immune-mediated inflammatory and infectious diseases, neuroinflammatory, neurological, and neurodegenerative diseases, as well as in cancer, and autoimmunity by itself. In this review, we summarize and critically highlight past, present, and future progress on the understanding of the role of cannabinoid-like molecules, mainly terpenes, as prospective therapeutics for different pathological conditions.

Triptolide ameliorates fine particulate matter-induced podocytes injury via regulating NF-κB signaling pathway

BACKGROUND

PM2.5 is associated closely with an increased risk of membranous nephropathy (MN), however, whether PM2.5 could induce podocytes injury, the underlying pathology for MN, has not be thoroughly studied. Triptolide, an active component in Tripterygium wilfordii Hook F, is frequently used to treat MN in China, but its effects on PM2.5-induced podocytes injury is still largely unknown. Therefore, we evaluated the effects of PM2.5 on podocytes, and explored whether triptolide could improve PM2.5-induced podocytes injury and the possible underlying mechanisms.

RESULTS

Podocytes were incubated with PM2.5 after being pre-treated with triptolide, viability, apoptosis rate and migratory capacity of podocytes were determined by CCK-8 assay, flow cytometry and Transwell assay, respectively. Additionally, the levels of lactate dehydrogenase (LDH), malondialdehyde (MDA), and superoxide dismutase (SOD) in podocytes, the cytoskeleton of podocytes, the protein expressions of nephrin, podocin, Bcl-2, Bax, nuclear factor kappa-B/p65 (NF-κB/p65) and phospho-inhibitor of NF-κB (p-IκBα) were measured. Our data showed that PM2.5 treatment significantly increased the disorganization of F-actin stress fibers, the damaged structural integrity of nucleus, the deranged and dissociated cytoskeleton in podocytes, increased the podocytes apoptosis rate, the levels of MDA and LDH, markedly up-regulated the protein expression of Bax, NF-κB/p65 and p-IκBα, down-regulated the protein expression of nephrin, podocin and Bcl-2, and significantly decreased the level of SOD, the migration rate and the viability of podocytes, compared with those of the untreated podocytes. These effects of PM2.5 on podocytes, however, were reversed by triptolide administration.

CONCLUSION

These results suggest that triptolide could prevent against PM2.5-induced podocytes injury via suppressing NF-κB signaling pathway.

Aldehyde dehydrogenase-positive melanoma stem cells in tumorigenesis, drug resistance and anti-neoplastic immunotherapy

Cancer stem cells (CSCs), a rare subset of cancer cells, are well known for their self-renewing capacity. CSCs play a critical role in therapeutic failure and are responsible for poor prognosis in leukemia and various solid tumors. However, it is still unclear how CSCs initiate carcinogenesis and evade the immune response. In humans, the melanoma initiating cells (MICs) are recognized as the CSCs in melanomas, and were verified to possess CSC potentials. The enzymatic system, aldehyde dehydrogenase (ALDH) is considered to be a specific marker for CSCs in several tumors. The expression of ALDH in MICs may be closely correlated with phenotypic heterogeneity, melanoma-genesis, metastasis, and drug resistance. The ALDH⁺ CSCs/MICs not only serve as an indicator for therapeutic efficacy, but have also become a target for the treat of melanoma. In this review, we initially introduce the multiple capacities of MICs in melanoma. Then, we summarize in vivo and in vitro studies that illustrate the relationship between ALDH and MICs. Furthermore, understanding of chemotherapy resistance in melanoma relies on ALDH⁺ MICs. Finally, we review studies that focus on melanoma immunotherapies, rendering ALDH a potential marker to evaluate the efficacy of anti-neoplastic therapies or an adjuvant anti-melanoma target.

Development and Validation of an HPLC-PDA Method for Biologically Active Quinonemethide Triterpenoids Isolated from Maytenus chiapensis

Background: Quinonemethide triterpenoids, known as celastroloids, constitute a relatively small group of biologically active compounds restricted to the Celastraceae family and, therefore, they are chemotaxonomic markers for this family. Among this particular type of metabolite, pristimerin and tingenone are considered traditional medicines in Latin America. The aim of this study was the isolation of the most abundant celastroloids from the root bark of Maytenus chiapensis, and thereafter, to develop an analytical method to identify pristimerin and tingenone in the Celastraceae species. Methods: Pristimerin and tingenone were isolated from the n-hexane-Et₂O extract of the root bark of M. chiapensis through chromatographic techniques, and were used as internal standards. Application of a validated RP HPLC-PDA method was developed for the simultaneous quantification of these two metabolites in three different extracts, n-hexane-Et₂O, methanol, and water, to determine the best extractor solvent. Results: Concentration values showed great variation between the solvents used for extraction, with the n-hexane⁻Et₂O extract being the richest in pristimerin and tingenone. Conclusions: M. chiapensis is a source of two biologically active quinonemethide triterpenoids. An analytical method was developed for the qualification and quantification of these two celastroloids in the root bark extracts of M. chiapensis. The validated method reported herein could be extended and be useful in analyzing Celastraceae species and real commercial samples.

Pristimerin enhances the effect of cisplatin by inhibiting the miR‑23a/Akt/GSK3β signaling pathway and suppressing autophagy in lung cancer cells

Lung cancer is a common type of cancer with a high mortality rate in China. Cisplatin (Cis) is one of the most effective broad‑spectrum chemotherapeutic drugs for the treatment of advanced lung cancer. However, Cis resistance remains an obstacle in the treatment of advanced lung cancer. Pristimerin (Pris), a naturally occurring triterpenoid quinone compound, not only possesses anticancer properties, but also enhances chemosensitivity. Therefore, the present study aimed to investigate whether Pris can enhance the chemosensitivity of lung cancer cells to Cis and identify the underlying mechanism. A Cell Counting kit‑8 and flow cytometry were used to determine cell viability, cell cycle progression and apoptosis in A549 and NCI‑H446 cells. Western blotting was used to determine cell apoptosis‑related, cell cycle‑related and autophagy‑related proteins. The results showed that Pris inhibited cell proliferation, and induced G0/G1 arrest and cell apoptosis in A549 and NCI‑H446 cells. The western blotting revealed that Pris effectively synergized with Cis to induce cell apoptosis by inhibiting the microRNA‑23a/Akt/glycogen synthase kinase 3β signaling pathway and suppressing autophagy. In vivo xenograft experiments confirmed that Pris effectively synergized with Cis to suppress tumor growth. Collectively, these results indicate that Pris synergized with Cis and that this may be a potential therapeutic strategy to overcome lung cancer.

Pristimerin targeting NF-κB pathway inhibits proliferation, migration, and invasion in esophageal squamous cell carcinoma cells

Esophageal squamous cell carcinoma (ESCC) is one of the leading causes of cancer-related death with poor prognosis in China. Identifying novel targeted therapies in ESCC is urgently needed. The aberrant activation of NF-κB signalling pathway is critical for prognosis and recurrence of ESCC, which make it a potential target in the treatment of ESCC. Here, we found that pristimerin inhibited ESCC cell proliferation, migration, invasion, induced cell apoptosis, and eliminated cancer stem-like cells (CSCs). It also showed a synergistic effect on ESCC when combined with 5-fluorouracil (5-FU). Moreover, pristimerin potently inhibited the growth of ESCC xenograft in nude mice. The anti-ESCC effects of pristimerin were demonstrated to be associated with the inhibition of NF-κB pathway by suppressing tumour necrosis factor α (TNFα)-induced IκBα phosphorylation, p65 translocation, and NF-κB-dependent gene expression. This study provides an evidence for the development of pristimerin to be a new therapeutic agent for ESCC.

SIGNIFICANCE OF THE STUDY

Although several approaches including surgery, chemotherapy, and radiotherapy had been applied in the treatment of ESCC, more effective targeted chemotherapies are required to increase the survival rates of patients. This study suggested that inhibiting NF-κB signalling pathway could be an effective approach for the treatment of ESCC. Pristimerin, a potent NF-κB inhibitor, exerted potent anti-ESCC effects both in vitro and in vivo, which may be a promising therapeutic agent for ESCC.