Enhanced chemoprevention by the combined treatment of pterostilbene and lupeol in B[a]P-induced mouse skin tumorigenesis

Chemotherapeutic potential of lupeol against cancer in pre-clinical model: A systematic review and meta-analysis

BACKGROUND

Extensive research on Lupeol's potential in cancer prevention highlights its ability to target various cancer-related factors. It regulates proliferative markers, modulates signaling pathways, including PI3K/AKT/mTOR, and influences inflammatory and apoptotic mechanisms. Additionally, Lupeol demonstrates selectivity in killing cancer cells while sparing normal cells, thus minimizing the risk of toxic effects on healthy tissues.

HYPOTHESIS

Therefore, we aimed to explore Lupeol's potential roles as a chemotherapeutic agent and as a sensitizer to chemotherapy by reviewing various animal-based studies published on its effects.

STUDY DESIGN

We conducted a comprehensive search across databases, including PubMed, PMC, Cochrane, EuroPMC, and ctri.gov.in to identify pertinent articles. Our focus was solely on published animal studies examining Lupeol's anti-cancer effects, with reviewers independently assessing bias risk and resolving discrepancies through consensus.

RESULT

20 studies were shortlisted. The results demonstrated that Lupeol brings changes in the tumor volume by [Hedges's g: -6.62; 95 % CI: -8.68, -4.56; τ2: 24.36, I2: 96.50 %; p < 0.05] and tumor weight by [Hedges's g: -3.97; 95 % CI: -5.20, -2.49; τ2: 2.70, I2: 79.27 %; p <0.05]. The high I2, negative Egger's value, and asymmetrical funnel plot show the publication bias among the studies. Further, Lupeol in combination with other chemotherapeutic agents showed better outcomes as compared to them alone [Hedges's g: -6.38; 95 % CI: -11.82, -0.94; τ2: 46.91; I2: 98.68 %; p <0.05]. Lupeol also targets various signaling molecules and pathways to exert an anti-cancer effect.

CONCLUSION

In conclusion, Lupeol significantly reduces tumor volume and weight. Combining Lupeol with other chemotherapy agents shows promise for enhancing anti-cancer effects. However, high variability among studies and evidence of publication bias suggest caution in interpreting results.

An Update on Phytochemicals in Redox Homeostasis: “Virtuous or Evil” in Cancer Chemoprevention?

Redox homeostasis, a dynamic process ensuring a balance between cellular oxidizing and reducing reactions, is crucial for maintaining healthy cellular physiology and regulating many biological processes, requiring continuous monitoring and fine-tuning. Reactive species play a critical role in intra/intercellular signaling, and each cell has a specific system guarding cellular redox homeostasis. ROS signaling and oxidative stress are involved in cancer initiation and progression. However, the generation of reactive species beyond the threshold level inside the tumor microenvironment is considered one of the therapeutic approaches. Various studies have shown that some phytochemicals can target the redox homeostasis of the tumor microenvironment. Recent advances have focused on developing and introducing phytochemical interventions as favorable therapeutic options against cancer. However, studies have also suggested the “virtuous” and “evil” impacts of phytochemicals. Some phytochemicals enhance therapeutic efficacy by promoting intracellular oxidant accumulation. However, under certain conditions, some phytochemicals may harm the cellular microenvironment to promote cancer and tend to target different pathways for cancer initiation and development instead of targeting redox homeostasis. In this context, this review is focused on providing an overall understanding of redox homeostasis and intends to highlight the potential positive and negative impacts of phytochemicals in redox homeostasis and disease development. We also discuss the recent nanotechnology-based advancements in combating cancer development.

Recent Advances in Health Benefits of Stilbenoids

Biological targeting or molecular targeting is the main strategy in drug development and disease prevention. However, the problem of "off-targets" cannot be neglected. Naturally derived drugs are preferred over synthetic compounds in pharmaceutical markets, and the main goals are high effectiveness, lower cost, and fewer side effects. Single-target drug binding may be the major cause of failure, as the pathogenesis of diseases is predominantly multifactorial. Naturally derived drugs are advantageous because they are expected to have multitarget effects, but not off-targets, in disease prevention or therapeutic actions. The capability of phytochemicals to modulate molecular signals in numerous diseases has been widely discussed. Among them, stilbenoids, especially resveratrol, have been well-studied, along with their potential molecular targets, including AMPK, Sirt1, NF-κB, PKC, Nrf2, and PPARs. The analogues of resveratrol, pterostilbene, and hydroxylated-pterostilbene may have similar, if not more, potential biological targeting effects compared with their original counterpart. Furthermore, new targets that have been discussed in recent studies are reviewed in this paper.

Lupeol and its derivatives as anticancer and anti-inflammatory agents: Molecular mechanisms and therapeutic efficacy

Lupeol is a natural triterpenoid that widely exists in edible fruits and vegetables, and medicinal plants. In the last decade, a plethora of studies on the pharmacological activities of lupeol have been conducted and have demonstrated that lupeol possesses an extensive range of pharmacological activities such as anticancer, antioxidant, anti-inflammatory, and antimicrobial activities. Pharmacokinetic studies have indicated that absorption of lupeol by animals was rapid despite its nonpolar characteristics, and lupeol belongs to class II BCS (biopharmaceutics classification system) compounds. Moreover, the bioactivities of some isolated or synthesized lupeol derivatives have been investigated, and these results showed that, with modification to C-3 or C-19, some derivatives exhibit stronger activities, e.g., antiprotozoal or anticancer activity. This review aims to summarize the advances in pharmacological and pharmacokinetic studies of lupeol in the last decade with an emphasis on its anticancer and anti-inflammatory activities, as well as the research progress of lupeol derivatives thus far, to provide researchers with the latest information, point out the limitations of relevant research at the current stage and the aspects that should be strengthened in future research.

Occurrence, Bioavailability, Anti-inflammatory, and Anticancer Effects of Pterostilbene

Supplementation with natural compounds found in fruits and vegetables has long been associated with a reduced risk of several types of cancer. Pterostilbene is a natural stilbenoid and a dimethylated analogue of resveratrol which is found primarily in blueberries. Pterostilbene exhibits a range of pharmacological properties, particularly anti-inflammatory and anticancer effects. Due to two methoxy groups in its skeleton, pterostilbene is more lipophilic than resveratrol and thus possesses higher intestinal permeability and cellular uptake and enhanced stability. Moreover, pterostilbene exhibits less toxicity and fewer adverse effects, providing it with superior potential in cancer chemoprevention and chemotherapy applications. Numerous research studies have demonstrated that pterostilbene possesses detoxification activities, mediating the anti-inflammation response, regulating the cell cycle, augmenting apoptosis, enhancing autophagy, and inhibiting tumor angiogenesis, invasion, and metastasis by modulating signal transduction pathways which block multiple stages of carcinogenesis. In this review, we illustrate that pterostilbene is a natural compound having bioavailability. The extensive metabolism of pterostilbene will be discussed. We also summarize recent research on pterostilbene's anti-inflammatory and anticancer properties in the multistage carcinogenesis process and related molecular mechanism and conclude that it should contribute to improved cancer management.

Chemosensitization of Therapy Resistant Tumors: Targeting Multiple Cell Signaling Pathways by Lupeol, A Pentacyclic Triterpene

Background:

The resistance of cancer cells to different therapies is one of the major stumbling blocks for successful cancer treatment. Various natural and pharmaceuticals drugs are unable to control drug-resistance cancer cell's growth. Also, chemotherapy and radiotherapy have several side effects and cannot apply to the patient in excess. In this context, chemosensitization to the therapy-resistant cells by non-toxic phytochemicals could be an excellent alternative to combat therapy-resistant cancers.

Objective:

To review the currently available literature on chemosensitization of therapy resistance cancers by Lupeol for clinically approved drugs through targeting different cell signaling pathways.

Methods:

We reviewed relevant published articles in PubMed and other search engines from 1999 to 2019 to write this manuscript. The key words used for the search were “Lupeol and Cancer”, “Lupeol and Chemosensitization”, “Lupeol and Cell Signaling Pathways”, “Cancer Stem Cells and Lupeol” etc. The published results on the chemosensitization of Lupeol were compared and discussed.

Results:

Lupeol chemosensitizes drug-resistant cancer cells for clinically approved drugs. Lupeol alone or in combination with approved drugs inhibits inflammation in different cancer cells through modulation of expression of IL-6, TNF-α, and IFN-γ. Lupeol, through altering the expression levels of BCL-2, BAX, Survivin, FAS, Caspases, and PI3K-AKT-mTOR signaling pathway, significantly induce cell deaths among therapy-resistant cells. Lupeol also modulates the molecules involved in cell cycle regulation such as Cyclins, CDKs, P53, P21, and PCNA in different cancer types.

Conclusion:

Lupeol chemosensitizes the therapy-resistant cancer cells for the treatment of various clinically approved drugs via modulating different signaling pathways responsible for chemoresistance cancer. Thus, Lupeol might be used as an adjuvant molecule along with clinically approved drugs to reduce the toxicity and increase the effectiveness.

Identification of Molecular Targets of Dietary Grape-Mediated Chemoprevention of Ultraviolet B Skin Carcinogenesis: A Comparative Quantitative Proteomics Analysis

We recently showed that dietary grape powder (GP) imparts considerable protection against ultraviolet B (UVB)-mediated skin carcinogenesis in SKH-1 mice. To determine molecular mechanisms of this response, we employed tandem mass tag (TMT) quantitative global proteomics approach on skin tumors from mice exposed to 180 mJ/cm² UVB twice per week and fed control or 5% GP diet. We found 2629 proteins modulated by GP feeding, with 34 identified using stringent cutoffs (false discovery rate (FDR) q-value ≤ 0.1, fold change ≥ 1.2, p-value ≤ 0.05, ≥ 3 unique peptides). Ingenuity Pathway Analysis helped identify seven proteins involved in protein ubiquitination, including the deubiquitinase UCHL5 and 6 subunits of the 20S proteasome (PSMA1,3,4,6 and PSMB4,7). A second data set without the FDR q-value identified 239 modulated proteins, seven of which are involved in protein ubiquitination. Further, 14 proteins involved in acute phase response signaling were modulated >1.5-fold, including acute phase proteins APCS, FGA, FGB, HP, HPX, and RBP1. Evaluation of upstream regulators found inhibition of ERK1/2 phosphorylation and NF-κB p65, and an increase in IκBα in GP-treated tumors. Overall, our data suggested that GP consumption may mitigate tumorigenesis by enhancing protein ubiquitination and degradation caused by oxidative stress, and manipulates an otherwise tumor-promoting anti-inflammatory environment.

Pterostilbene Activates the Nrf2-Dependent Antioxidant Response to Ameliorate Arsenic-Induced Intracellular Damage and Apoptosis in Human Keratinocytes

The NF-E2 p45-related factor 2 (Nrf2), a transcription factor that regulates the cellular adaptive response to oxidative stress, is a target for limiting tissue damage from exposure to environmental toxins, including arsenic. In the current study, we determine whether Pterostilbene (Pts), as a potent activator of Nrf2, has a protective effect on arsenic-induced cytotoxicity and apoptosis in human keratinocytes. Human keratinocytes (HaCaT) or mouse epidermal cells (JB6) were pretreated with Pts for 24 h prior to arsenic treatment. Harvested cells were analyzed by MTT, DCFH-DA, commercial kits, Flow cytometry assay and western blot analysis. Our results demonstrated that Pts effectively regulated the viability in HaCaT and JB6 cells, decreased the reactive oxygen species (ROS) generation and lipid peroxidation (MDA), and improved the NaAsO₂-induced depletion of superoxide dismutase (SOD). Moreover, Pts treatment further dramatically inhibited NaAsO₂-induced apoptosis, specifically the mitochondrial mediation of apoptosis, which coincided with the effective recovery of NaAsO₂-induced mitochondrial membrane potential (ΔΨm) depolarization and cytochrome c release from the mitochondria. Furthermore, arsenic-induced decrease of anti-apoptotic factor Bcl-2 and Bcl-xl, and increase of pro-apoptotic factor Bax and Bad, as well as survival signal related factor caspase 3 activation were reversed by Pts treatment. Further mechanistic studies confirmed that Pts increased antioxidant enzyme expression in a dose-dependent manner, which was related to Nrf2 nuclear translocation. In addition, the effects of Pts on NaAsO₂-induced cell viability were largely weakened when Nrf2 was knocked down. Together, our results provide evidence for the use of Pts to activate the Nrf2 pathway to alleviate arsenic-induced dermal damage.

Encapsulation of pterostilbene in nanoemulsions: influence of lipid composition on physical stability, in vitro digestion, bioaccessibility, and Caco-2 cell monolayer permeability

Nanoemulsions fabricated using medium chain triglycerides as carrier lipid are more effective for delivering pterostilbene than long chain triglycerides.

Traditional and ethnobotanical dermatology practices in Romania and other Eastern European countries

The geographic and ecologic specificity of Romania and other Eastern European countries has resulted in the development of an exceptional diversity of medicinal plants. The purpose of this study was to provide an overview of the ethnobotanical dermatology practices based on the use of medicinal plants in this region. The indications, ethnopharmacologic activities, parts used, and administration of 106 medicinal plants are provided. We also discuss the relative importance of these species, using two modified indices of quantitative ethnobotany: Use Value Index and Relative Dermatologic Importance, which were calculated on the basis of etic constructions (indications and ethnopharmacologic activities). The species identified to have the highest dermatologic importance (on a scale of 100) were Brassica oleracea L. (100), Matricaria chamomilla L. (79.17), Arctium lappa L. (74.82), Daucus carota L. (72.28), Equisetum arvense L. (70.47), Juglans regia L. (69.93), Populous nigra L. (65.94), Symphytum officinale L. (63.59), Chelidonium majus L. (57.78), Calendula officinalis L. (57.78), Achillea millefolium L. (57.43), Melilotus officinalis L. (55.25), Allium cepa L. (51.45), Quercus robur L. (51.08), and Betula spp. (50.91). This preliminary study on ethnobotanical dermatology practices indicates that Eastern European traditional medical knowledge represents an important heritage that is currently underexploited.