Plumbagin Suppresses Breast Cancer Progression by Downregulating HIF-1α Expression via a PI3K/Akt/mTOR Independent Pathway under Hypoxic Condition

The phytochemical plumbagin: mechanism behind its "pleiotropic" nature and potential as an anticancer treatment

Chemotherapeutics are most often used to treat cancer, but side effects, drug resistance, and toxicity often compromise their effectiveness. In contrast, phytocompound plumbagin possesses a distinct pleiotropic nature, targeting multiple signaling pathways, such as ROS generation, cell death, cellular proliferation, metastasis, and drug resistance, and is shown to enhance the efficacy of chemotherapeutic drugs. Plumbagin has been shown to act synergistically with various chemotherapeutic drugs and enhance their efficacy in drug-resistant cancers. The pleiotropic nature is believed to be due to plumbagin's unique structure, which contains a naphthoquinone ring and a hydroxyl group responsible for plumbagin's various biological responses. Despite limitations such as restricted bioavailability and delivery, recent developments aim to address these challenges and harness the potential of plumbagin as an anticancer therapeutics. This review delves into the structural aspect of the plumbagin molecule contributing to its pleiotropic nature, explores the diverse mechanism that it targets, and discusses emerging strategies to overcome its limitations.

Pharmacological Features and Therapeutic Implications of Plumbagin in Cancer and Metabolic Disorders: A Narrative Review

Plumbagin (PLB) is a naphthoquinone extracted from Plumbago indica. In recent times, there has been a growing body of evidence suggesting the potential importance of naphthoquinones, both natural and artificial, in the pharmacological world. Numerous studies have indicated that PLB plays a vital role in combating cancers and other disorders. There is substantial evidence indicating that PLB may have a significant role in the treatment of breast cancer, brain tumours, lung cancer, hepatocellular carcinoma, and other conditions. Moreover, its potent anti-oxidant and anti-inflammatory properties offer promising avenues for the treatment of neurodegenerative and cardiovascular diseases. A number of studies have identified various pathways that may be responsible for the therapeutic efficacy of PLB. These include cell cycle regulation, apoptotic pathways, ROS induction pathways, inflammatory pathways, and signal transduction pathways such as PI3K/AKT/mTOR, STAT3/PLK1/AKT, and others. This review aims to provide a comprehensive analysis of the diverse pharmacological roles of PLB, examining the mechanisms through which it operates and exploring its potential applications in various medical conditions. In addition, we have conducted a review of the various formulations that have been reported in the literature with the objective of enhancing the efficacy of the compound. However, the majority of the reviewed data are based on in vitro and in vivo studies. To gain a comprehensive understanding of the safety and efficacy of PLB in humans and to ascertain its potential integration into therapeutic regimens for cancer and chronic diseases, rigorous clinical trials are essential. Finally, by synthesizing current research and identifying gaps in knowledge, this review seeks to enhance our understanding of PLB and its therapeutic prospects, paving the way for future studies and clinical applications.

Plumbagin ameliorates LPS-induced acute lung injury by regulating PI3K/AKT/mTOR and Keap1-Nrf2/HO-1 signalling pathways

Acute lung injury (ALI) is a major pathophysiological problem characterized by severe inflammation, resulting in high morbidity and mortality. Plumbagin (PL), a major bioactive constituent extracted from the traditional Chinese herb Plumbago zeylanica, has been shown to possess anti-inflammatory and antioxidant pharmacological activities. However, its protective effect on ALI has not been extensively studied. The objective of this study was to investigate the protective effect of PL against ALI induced by LPS and to elucidate its possible mechanisms both in vivo and in vitro. PL treatment significantly inhibited pathological injury, MPO activity, and the wet/dry ratio in lung tissues, and decreased the levels of inflammatory cells and inflammatory cytokines TNF-α, IL-1β, IL-6 in BALF induced by LPS. In addition, PL inhibited the activation of the PI3K/AKT/mTOR signalling pathway, increased the activity of antioxidant enzymes CAT, SOD, GSH and activated the Keap1/Nrf2/HO-1 signalling pathway during ALI induced by LPS. To further assess the association between the inhibitory effects of PL on ALI and the PI3K/AKT/mTOR and Keap1/Nrf2/HO-1 signalling, we pretreated RAW264.7 cells with 740Y-P and ML385. The results showed that the activation of PI3K/AKT/mTOR signalling reversed the protective effect of PL on inflammatory response induced by LPS. Moreover, the inhibitory effects of PL on the production of inflammatory cytokines induced by LPS also inhibited by downregulating Keap1/Nrf2/HO-1 signalling. In conclusion, the results indicate that the PL ameliorate LPS-induced ALI by regulating the PI3K/AKT/mTOR and Keap1-Nrf2/HO-1 signalling, which may provide a novel therapeutic perspective for PL in inhibiting ALI.

Evaluation of molecular effects associated with apoptosis, tumour progression, angiogenesis and metastasis by a novel combination of drugs with ormeloxifene in triple negative breast cancer cells

Aim

To investigate the molecular effects of a novel combination [sertraline and plumbagin (comb) with ormeloxifene (Orm)] for anticancer activity in triple negative breast cancer cell line "MDA-MB-231".

Methods

The cytotoxic effect of the drugs was analyzed by the MTT assay and nuclear morphological changes by acridine orange/ethidium bromide (AO/EB) staining. Induction of apoptosis by annexin V-FITC staining, active caspase-3 detection and cell cycle analysis were studied in vitro on "MDA-MB-231" cells. The qRT-PCR was done to explore the upregulation and down regulation of targeted genes for angiogenesis, metastasis, tumor suppression and protein folding on the triple negative breast cancer cells. The preliminary anti-angiogenic effect of the drugs was assessed by chorioallantoic membrane (CAM) assay.

Results

Orm showed inhibitory effects in "MDA-MB-231" cells in a dose and time dependent manner whereas; the drugs in combination gave better cytotoxic effects in the screening MTT assay. Orm + comb was more effective than Orm alone in eliciting apoptosis as well as inhibited the single cell to grow into a colony. CAM assay using Orm and Orm + comb suggested the anti-angiogenic potential which was further confirmed by the downregulation of VEGF in "MDA-MB-231" cells by qRT-PCR studies. The combination was found to effectively upregulate the expression of P53 and P21 and downregulate the gene expression of zinc finger E-box binding homeobox 1 (ZEB1) and heat shock protein 70 (HSP70) in "MDA-MB-231" cancer cells.

Conclusions

Collectively this study reveals the efficacy of Orm + comb as more significant than the clinically used tamoxifen (Tam). The study elucidates the promising novelty of the combination as a potential chemotherapeutic intervention for mitigating the aggressiveness of triple negative breast cancer and it addresses the intrinsic resistance caused by single drug treatments.

Plumbagin induces ferroptosis in colon cancer cells by regulating p53-related SLC7A11 expression

Objective

This study examined the mechanism through which plumbagin induces ferroptosis of colon cancer cells.

Methods

CCK-8 assay was performed to examine the viability of colon cancer cells (SW480 and HCT116 cells) after they were treated with 0-, 5-, 10-, 15- and 20-μmol/L plumbagin. Colony formation assay and Transwell assay were used to examine the effects of 15-μmol/L plumbagin on the proliferation, invasive ability. The ferroptosis of SW480 and HCT116 cells and the expression of p-p53, p53 and SLC7A11 were analysed. The effects of blocking necrosis, apoptosis and ferroptosis on the anti-cancer effects of plumbagin were examined. After p53 was silenced, the effects of plumbagin on proliferation, invasion, ferroptosis and SLC7A11 expression were assessed. A tumour-bearing nude mouse model was used to examine the effects of p53 silencing and/or plumbagin on tumour growth, ferroptosis and SLC7A11 expression.

Results

Plumbagin inhibited the proliferation of SW480 and HCT116 cells and their invasive and colony-forming abilities. It increased Fe2+ levels but significantly decreased GSH and GPX4 levels. When ferroptosis was inhibited, the effects of plumbagin on colon cancer cells were significantly alleviated. Plumbagin promoted the expression and phosphorylation of p53 and inhibited the mRNA and protein levels of SLC7A11. Silencing of p53 counteracted the effects of plumbagin on the ferroptosis and biological behaviour of SW480 and HCT116 cells. In mouse models of colon cancer, silencing of p53 attenuated the tumour-suppressing effects of plumbagin as well as its inhibitory effects on the protein level of SLC7A11 and restored the expression of GSH and GPX4.

Conclusion

Plumbagin promotes ferroptosis and inhibits cell proliferation and invasion by decreasing the protein expression of SLC7A11 through p53.

Use of antioxidant nanoliposomes for co-delivery of PTEN plasmids and plumbagin to induce apoptosis in hepatic cancer cells

Hepatocellular carcinoma remains a challenging contributor to the global cancer and related mortality, and claims approximately 800,000 deaths each year. Dysregulation or loss of function mutations involving the tumor suppressor gene, phosphatase and tensin homolog deleted on chromosome ten (PTEN), has been well-characterized in various cancers to elicit anomalous cell proliferation and oncogenic transformation. However, the delivery and bioavailability of genes/drugs of interest to carcinomas remains a serious bottleneck behind the success of any anti-cancer formulation. In this study, we have engineered nanoliposomes containing PTEN plasmids, plumbagin, and antioxidant cerium oxide nanoparticles (Lipo-PTEN-Plum) to restore the PTEN expression and inhibit the AKT/PI3K pathway. The Lipo-PTEN-Plum was quasi-spherical in shape with ∼110 nm diameter and ∼64% plumbagin loading efficiency. The Lipo-PTEN-Plum was successfully internalized HepG2 cells, restore PTEN expression and inhibit PI3K/AKT pathway to induce death in cells grown in monolayer and in form of spheroids. Mechanistically, the formulation showed G2/M cell cycle arrest, DNA damage and apoptosis in hepatic cancer cells. Other cellular events such as Caspase-7 overexpression and PI3K (phosphoinositide 3-kinase), AKT (a serine/threonine protein kinase), PARP [Poly (ADP-ribose) polymerases], and mTOR (Mammalian target of rapamycin) inhibition led to the apoptosis in hepatic cancer cells. The mRNA expression profile of PTEN, PI3K, AKT3, Caspase-7, PARP and mTOR proteins, primarily controlling the cancer cell proliferation and apoptosis, suggest that exogenous supply of PTEN could regulate the expression of oncogenic proteins and thus cancer progression.

Plumbagin induces apoptosis, cell cycle arrest, and inhibits protein synthesis in LoVo colon cancer cells: A proteomic analysis

Extracted from the roots of Plumbago zeylanica L., plumbagin is a natural naphthoquinone with potential as an anticancer compound. However, no studies have investigated its impact on LoVo (colon cancer) cells, and the specific mechanisms by which plumbagin exerts its anticancer effects remain to be established. The anticancer potential of plumbagin against LoVo cells was evaluated using a battery of assays, including MTT assay, clone formation assay, transwell chamber invasion assay, and wound-curing assay. Cell cycle analysis and cell apoptosis analysis were conducted to break down the anticancer impact of plumbagin on LoVo cells. A label-free proteomics technology was employed to investigate alterations in protein expression in LoVo cells treated with plumbagin. Our investigation indicated that plumbagin markedly inhibited the LoVo cells proliferation, and induced the apoptosis in LoVo cells, simultaneously induced G0/G1 phase cell cycle arrest. The LC-MS/MS proteomics assay revealed 78 proteins that were differentially expressed upon treatment with plumbagin. Bioinformatics and functional analyses indicated that these proteins were predominantly involved in protein synthesis and translation. Our findings revealed that multiple mechanisms are involved in the anticancer activity of plumbagin against LoVo cells, resulting in decreased cell viability. Proteomic analysis suggests that plumbagin may impede protein synthesis by reducing the expression of eukaryotic initiation factors. Our findings demonstrate that plumbagin exerts its anticancer activity against LoVo cells through multiple mechanisms, including inhibition of cell proliferation, induction of apoptosis, cell cycle arrest, and disruption of protein synthesis. These results provide new insights into the therapeutic potential of plumbagin for colon cancer treatment.

Hypoxia inducible factor-1α (HIF-1α) in breast cancer: The crosstalk with oncogenic and onco-suppressor factors in regulation of cancer hallmarks

Low oxygen level at tumor microenvironment leads to a condition, known as hypoxia that is implicated in cancer progression. Upon hypoxia, HIF-1α undergoes activation and due to its oncogenic function and interaction with other molecular pathways, promotes tumor progression. The HIF-1α role in regulating breast cancer progression is described, Overall, HIF-1α has upregulation in breast tumor and due to its tumor-promoting function, its upregulation is in favor of breast tumor progression. HIF-1α overexpression prevents apoptosis in breast tumor and it promotes cell cycle progression. Silencing HIF-1α triggers cycle arrest and decreases growth. Migration of breast tumor enhances by HIF-1α signaling and it mainly induces EMT in providing metastasis. HIF-1α upregulation stimulates drug resistance and radio-resistance in breast tumor. Furthermore, HIF-1α signaling induces immune evasion of breast cancer. Berberine and pharmacological intervention suppress HIF-1α signaling in breast tumor and regulation of HIF-1α by non-coding RNAs occurs. Furthermore, HIF-1α is a biomarker in clinic.

Biological Potential of Carnivorous Plants from Nepenthales

Since Charles Darwin and his book carnivorous plants have aroused interest and heated debate. In addition, there is growing interest in this group of plants as a source of secondary metabolites and in the application of their biological activity. The aim of this study was to trace the recent literature in search of the application of extracts obtained from families Droseraceae, Nepenthaceae, and Drosophyllaceae to show their biological potential. The data collected in the review clearly indicate that the studied Nepenthales species have great biological potential in terms of antibacterial, antifungal, antioxidant, anti-inflammatory, and anticancer use. We proposed that further investigations should include: (i) bioactivity-guided investigations of crude plant extract to connect a particular type of action with a specific compound or a group of metabolites; (ii) a search for new bioactive properties of carnivorous plants; (iii) establishment of molecular mechanisms associated with specific activity. Furthermore, further research should be extended to include less explored species, i.e., Drosophyllum lusitanicum and especially Aldrovanda vesiculosa.