Physapubescin selectively induces apoptosis in VHL-null renal cell carcinoma cells through down-regulation of HIF-2α and inhibits tumor growth

Withanolides: Promising candidates for cancer therapy

Natural products have played a significant role throughout history in the prevention and treatment of numerous diseases, particularly cancers. As a natural product primarily derived from various medicinal plants in the Withania genus, withanolides have been shown in several studies to exhibit potential activities in cancer treatment. Consequently, understanding the molecular mechanism of withanolides could herald the discovery of new anticancer agents. Withanolides have been studied widely, especially in the last 20 years, and attracted the attention of numerous researchers. Currently, over 1200 withanolides have been classified, with approximately a quarter of them having been reported in the literature to be able to modulate the survival and death of cancer cells through multiple avenues. To what extent, though, has the anticancer effects of these compounds been studied? How far are they from being developed into clinical drugs? What are their potential, characteristic features, and challenges? In this review, we elaborate on the current knowledge of natural compounds belonging to this class and provide an overview of their natural sources, anticancer activity, mechanism of action, molecular targets, and implications for anticancer drug research. In addition, direct targets and clinical research to guide the design and implementation of future preclinical and clinical studies to accelerate the application of withanolides have been highlighted.

Biochemical Screening, Fabrication of Green Nanoparticles and Its Antimicrobial, and Antioxidant Studies of Endophytic Fungus Phlebia Species

Endophytes are organism dwelling totally dynamic and novel biotopes this makes them able to produce novel biochemicals that may become assets to the future. This study aims at understanding the biochemical components of the endophytic fungus Phlebia sp. synthesis of gold and silver nanoparticles from it, and the antimicrobial as well as antioxidant ability of these green synthesised nanoparticles. Aqueous fungal extract was subjected for HRLCMS analysis which revealed 34 biochemicals within the extract. Silver and gold nanoparticles were also produced from the fungal extract. UV-vis analysis revealed a peak at 450 nm for silver nanoparticle and 550 nm for gold nanoparticles. FESEM analysis confirmed the presence of these nanoparticles with its spherical shape. Both of these nanoparticles were able to produce a conspicuous zone of inhibition in the antimicrobial tests against Escherichia coli, Salmonella paratyphi. For both of the organisms under study, a concentration-dependent expansion of the zone of inhibition was discovered in the nanoparticles. However, with silver nanoparticles, a relatively high zone of inhibition and vulnerability of the organism was discovered. Four in vitro free radical scavenging assays, including the DPPH, Hydroxyl, Superoxide, and Nitric oxide radical scavenging assays, were used for antioxidant analysis. The results of every test demonstrated that green synthesised silver nanoparticles had higher activity than gold nanoparticles. All of the tests showed that silver nanoparticles were more active than gold nanoparticles with the maximum value of 86.254 ± 0.296% being discovered at the greatest concentration of superoxide radical scavenging assay.

Physalis pubescens L. branch and leaf extracts inhibit lymphoma proliferation by inducing apoptosis and cell cycle arrest

Physalis pubescens L. is an annual or perennial plant in the family Solanaceae It is used in traditional medicine for treating sore throats, coughs, urinary discomfort, and astringent pain, and externally for pemphigus and eczema in northern China. The proliferation inhibitory activity and mechanisms of the ethyl acetate extract (PHY-EA) from the leaves of Physalis pubescens were investigated. High performance liquid chromatography was used to identify the chemical composition of PHY-EA; sulforhodamine B was used to detect the proliferation inhibitory effect of PHY-EA on MCF-7, CA-46, Hela, HepG2, B16, and other tumor cells; flow cytometry was used to detect the effect of PHY-EA on the lymphoma cell cycle and apoptosis; Western blot was used to detect the expression of the cycle- and apoptosis-related proteins. The expression of Ki-67 and cleaved caspase 3 was detected by immunohistochemistry. The results showed that PHY-EA contained physalin B, physalin O, and physalin L. PHY-EA blocked the cell cycle of G2/M→G0/G1 in lymphoma cells and induced apoptosis in tumor cells. Mouse transplantation tumor experiments showed that PHY-EA had a significant inhibitory effect on mouse transplantation tumors, and the tumor volume and weight were significantly reduced. In conclusion, PHY-EA has a good antiproliferative effect on Burkkit lymphoma, indicating its potential medicinal value.

Identification of HMGCR as the anticancer target of physapubenolide against melanoma cells by in silico target prediction

Physapubenolide (PB), a withanolide-type compound extracted from the traditional herb Physalis minima L., has been demonstrated to exert remarkable cytotoxicity against cancer cells; however, its molecular mechanisms are still unclear. In this study, we demonstrated that PB inhibited cell proliferation and migration in melanoma cells by inducing cell apoptosis. The anticancer activity of PB was further verified in a melanoma xenograft model. To explore the mechanism underlying the anticancer effects of PB, we carried out an in silico target prediction study, which combined three approaches (chemical similarity searching, quantitative structure-activity relationship (QSAR), and molecular docking) to identify the targets of PB, and found that PB likely targets 3-hydroxy-methylglutaryl CoA reductase (HMGCR), the rate-limiting enzyme of the mevalonate pathway, which promotes cancer cell proliferation, migration, and metastasis. We further demonstrated that PB interacted with HMGCR, decreased its protein expression and inhibited the HMGCR/YAP pathway in melanoma cells. In addition, we found that PB could restore vemurafenib sensitivity in vemurafenib-resistant A-375 cells, which was correlated with the downregulation of HMGCR. In conclusion, we demonstrate that PB elicits anticancer action and enhances sensitivity to vemurafenib by targeting HMGCR.

Role of Plant-Derived Active Constituents in Cancer Treatment and Their Mechanisms of Action

Despite significant technological advancements in conventional therapies, cancer remains one of the main causes of death worldwide. Although substantial progress has been made in the control and treatment of cancer, several limitations still exist, and there is scope for further advancements. Several adverse effects are associated with modern chemotherapy that hinder cancer treatment and lead to other critical disorders. Since ancient times, plant-based medicines have been employed in clinical practice and have yielded good results with few side effects. The modern research system and advanced screening techniques for plants’ bioactive constituents have enabled phytochemical discovery for the prevention and treatment of challenging diseases such as cancer. Phytochemicals such as vincristine, vinblastine, paclitaxel, curcumin, colchicine, and lycopene have shown promising anticancer effects. Discovery of more plant-derived bioactive compounds should be encouraged via the exploitation of advanced and innovative research techniques, to prevent and treat advanced-stage cancers without causing significant adverse effects. This review highlights numerous plant-derived bioactive molecules that have shown potential as anticancer agents and their probable mechanisms of action and provides an overview of in vitro, in vivo and clinical trial studies on anticancer phytochemicals.

The Hypoxic Microenvironment Induces Stearoyl-CoA Desaturase-1 Overexpression and Lipidomic Profile Changes in Clear Cell Renal Cell Carcinoma

Simple Summary

Clear cell renal cell carcinoma (ccRCC) is characterized by a high rate of cell proliferation and an extensive accumulation of lipids. Uncontrolled cell growth usually generates areas of intratumoral hypoxia that define the tumor phenotype. In this work, we show that, under these microenvironmental conditions, stearoyl-CoA desaturase-1 is overexpressed. This enzyme induces changes in the cellular lipidomic profile, increasing the oleic acid levels, a metabolite that is essential for cell proliferation. This work supports the idea of considering stearoyl-CoA desaturase-1 as an exploitable therapeutic target in ccRCC.

Abstract

Clear cell renal cell carcinoma (ccRCC) is the most common histological subtype of renal cell carcinoma (RCC). It is characterized by a high cell proliferation and the ability to store lipids. Previous studies have demonstrated the overexpression of enzymes associated with lipid metabolism, including stearoyl-CoA desaturase-1 (SCD-1), which increases the concentration of unsaturated fatty acids in tumor cells. In this work, we studied the expression of SCD-1 in primary ccRCC tumors, as well as in cell lines, to determine its influence on the tumor lipid composition and its role in cell proliferation. The lipidomic analyses of patient tumors showed that oleic acid (18:1n-9) is one of the major fatty acids, and it is particularly abundant in the neutral lipid fraction of the tumor core. Using a ccRCC cell line model and in vitro-generated chemical hypoxia, we show that SCD-1 is highly upregulated (up to 200-fold), and this causes an increase in the cellular level of 18:1n-9, which, in turn, accumulates in the neutral lipid fraction. The pharmacological inhibition of SCD-1 blocks 18:1n-9 synthesis and compromises the proliferation. The addition of exogenous 18:1n-9 to the cells reverses the effects of SCD-1 inhibition on cell proliferation. These data reinforce the role of SCD-1 as a possible therapeutic target.

Withanolides isolated from Tubocapsicum anomalum and their antiproliferative activity

Seven undescribed withanolides (1-7) and six artificial withanolides (8-13), along with 20 known compounds (14-33) were isolated from the aerial parts of Tubocapsicum anomalum. Their structures were confirmed by comprehensive spectroscopic analyses. The absolute configuration of compound 1 was defined by single-crystal X-ray crystallography. All isolates were evaluated for their antiproliferative effects against five human tumor cell lines (Hep3B, MDA-MB-231, SW480, HCT116 and A549), among which compound 24 (tubocapsanolide A) exhibited the highest activities against the MDA-MB-231 cells with an IC₅₀ value of 1.89 ± 1.03 μM. Further studies showed that 24 exhibited significant damage to mitochondria in MDA-MB-231 cells, including excess reactive oxygen species, decreased mitochondrial membrane potential, and apoptosis initiation. In addition, compound 24 also inhibited cell migration. These findings show that tubocapsanolide A may be a promising molecule for triple-negative breast cancer treatment and merit further evaluation.

New cytotoxic withanolides from Physalis minima

Phytochemical investigation of Physalis minima led to the isolation of six new withanolides, including physaminilides HK (1-4), two artificial withanolides (5-6), and 19 known ones (7-25). Their structures were elucidated on the basis of spectroscopic analysis, including NMR and electronic circular dichroism (ECD) data. The isolates were evaluated for their cytotoxic activities against A375 human melanoma cells. Compounds 1, 8-9, 12-13, 15-17 and 19 exhibited significant cytotoxic activities with IC₅₀ values in the range of 1.2-7.5 μM.

Targeting β2-Adrenergic Receptors Shows Therapeutical Benefits in Clear Cell Renal Cell Carcinoma from Von Hippel-Lindau Disease

Von Hippel–Lindau (VHL), is a rare autosomal dominant inherited cancer in which the lack of VHL protein triggers the development of multisystemic tumors such us retinal hemangioblastomas (HB), CNS-HB, and clear cell renal cell carcinoma (ccRCC). ccRCC ranks third in terms of incidence and first in cause of death. Standard systemic therapies for VHL-ccRCC have shown limited response, with recurrent surgeries being the only effective treatment. Targeting of β2-adrenergic receptor (ADRB) has shown therapeutic antitumor benefits on VHL-retinal HB (clinical trial) and VHL-CNS HB (in vitro). Therefore, the in vitro and in vivo antitumor benefits of propranolol (ADRB-1,2 antagonist) and ICI-118,551 (ADRB-2 antagonist) on VHL^−/− ccRCC primary cultures and 786-O tumor cell lines have been addressed. Propranolol and ICI-118,551 activated apoptosis inhibited gene and protein expression of HIF-2α, CAIX, and VEGF, and impaired partially the nuclear internalization of HIF-2α and NFĸB/p65. Moreover, propranolol and ICI-118,551 reduced tumor growth on two in vivo xenografts. Finally, ccRCC patients receiving propranolol as off-label treatment have shown a positive therapeutic response for two years on average. In summary, propranolol and ICI-118,551 have shown antitumor benefits in VHL-derived ccRCC, and since ccRCCs comprise 63% of the total RCCs, targeting ADRB2 becomes a promising drug for VHL and other non-VHL tumors.

Phytochemicals in Cancer Treatment: From Preclinical Studies to Clinical Practice

Cancer is a severe health problem that continues to be a leading cause of death worldwide. Increasing knowledge of the molecular mechanisms underlying cancer progression has led to the development of a vast number of anticancer drugs. However, the use of chemically synthesized drugs has not significantly improved the overall survival rate over the past few decades. As a result, new strategies and novel chemoprevention agents are needed to complement current cancer therapies to improve efficiency. Naturally occurring compounds from plants known as phytochemicals, serve as vital resources for novel drugs and are also sources for cancer therapy. Some typical examples include taxol analogs, vinca alkaloids such as vincristine, vinblastine, and podophyllotoxin analogs. These phytochemicals often act via regulating molecular pathways which are implicated in growth and progression of cancer. The specific mechanisms include increasing antioxidant status, carcinogen inactivation, inhibiting proliferation, induction of cell cycle arrest and apoptosis; and regulation of the immune system. The primary objective of this review is to describe what we know to date of the active compounds in the natural products, along with their pharmacologic action and molecular or specific targets. Recent trends and gaps in phytochemical based anticancer drug discovery are also explored. The authors wish to expand the phytochemical research area not only for their scientific soundness but also for their potential druggability. Hence, the emphasis is given to information about anticancer phytochemicals which are evaluated at preclinical and clinical level.

New withanolides from Physalis minima and their cytotoxicity against A375 human melanoma cells

The new withanolides physaminilide A–G (1–7), and two artificial withanolides (8–9) were isolated from Physalis minima. Compounds 2, 5 and 8 exhibited significant cytotoxicity towards human tumor cells.

Cell death-related molecules and biomarkers for renal cell carcinoma targeted therapy

Renal cell carcinoma (RCC) is not sensitive to conventional radio- and chemotherapies and is at least partially resistant to impairments in cell death-related signaling pathways. The hallmarks of RCC formation include diverse signaling pathways, such as maintenance of proliferation, cell death resistance, angiogenesis induction, immune destruction avoidance, and DNA repair. RCC diagnosed during the early stage has the possibility of cure with surgery. For metastatic RCC (mRCC), molecular targeted therapy, especially antiangiogenic therapy (e.g., tyrosine kinase inhibitors, TKIs, such as sunitinib), is one of the main partially effective therapeutics. Various forms of cell death that may be associated with the resistance to targeted therapy because of the crosstalk between targeted therapy and cell death resistance pathways were originally defined and differentiated into apoptosis, necroptosis, pyroptosis, ferroptosis and autophagic cell death based on cellular morphology. Particularly, as a new form of cell death, T cell-induced cell death by immune checkpoint inhibitors expands the treatment options beyond the current targeted therapy. Here, we provide an overview of cell death-related molecules and biomarkers for the progression, prognosis and treatment of mRCC by targeted therapy, with a focus on apoptosis and T cell-induced cell death, as well as other forms of cell death.

The uremic toxin p-cresyl sulfate induces proliferation and migration of clear cell renal cell carcinoma via microRNA-21/ HIF-1α axis signals

p-Cresyl sulfate (pCS), a uremic toxin, can cause renal damage and dysfunction. Studies suggest that renal dysfunction increases the prevalence of renal cancer. However, the effect of pCS on the proliferation and migration of renal cancer is unclear. Clear cell renal cell carcinoma (ccRCC) expresses mutant von Hippel-Lindau gene and is difficult to treat. Hypoxia-inducible factor-1α and 2-α (HIF-1α and HIF-2α) as well as microRNA-21 (miR-21) can regulate the proliferation and migration of ccRCC cells. However, the association between HIF-α and miR-21 in ccRCC remains unclear. Therefore, the effects of pCS on ccRCC cells were investigated for HIF-α and miR-21 signals. Our results showed that pCS induced overexpression of HIF-1α and promoted the proliferation and regulated epithelial-mesenchymal transition-related proteins, including E-cadherin, fibronectin, twist and vimentin in ccRCC cells. pCS treatment increased miR-21 expression. Specifically, inhibition of miR-21 blocked pCS-induced proliferation and migration. Taken together, the present results demonstrate that pCS directly induced the proliferation and migration of ccRCC cells through mechanisms involving miR-21/HIF-1α signaling pathways.

Presence of Intratumoral Calcifications and Vasculature Is Associated With Poor Overall Survival in Clear Cell Renal Cell Carcinoma

PURPOSE

The objective of this study was to explore the prognostic significance of the preoperative computed tomography (CT) features in clear cell renal cell carcinoma.

PATIENTS AND METHODS

The clinical data and CT data from 210 patients (1 grade 1, 84 grade 2, 92 grade 3, and 32 grade 4) generated with The Cancer Imaging Archive were reviewed. Overall survival was assessed using Kaplan-Meyer analysis. The relationship between CT features and survivals were evaluated using univariate and multivariable Cox regression analysis.

RESULTS

The follow-up occurred between 13 and 3989 days (median, 1405 days; mean, 1434 days).On univariate Cox regressions, 4 preoperative CT features (intratumoral calcifications: yes vs no hazard ratio [HR], 2.054; 95% confidence interval [CI], 1.231-3.428; renal vein invasion: yes vs no HR, 2.013; 95% CI, 1.218-3.328; collecting system invasion: yes vs no HR, 2.139; 95% CI, 1.286-3.558; gross appearance of intratumoral vasculature: yes vs no HR, 2.385; 95% CI, 1.454-3.915) were significantly associated with overall survival (all P < 0.05). On multivariable Cox regression analysis, predictors of mortality in clear cell renal cell carcinoma were the presence of intratumoral calcifications (HR, 1.718; 95% CI, 1.014-2.911; P = 0.044) and gross appearance of intratumoral vasculature (HR, 2.137; 95% CI, 1.284-3.557; P = 0.003).

CONCLUSIONS

Presence of intratumoral calcifications and vasculature can be potential prognostic features to screen patients for unfavorable prognosis.

Withapubesides A-D: natural inducible nitric oxide synthase (iNOS) inhibitors from Physalis pubescens

Four new steroid glycosides, withapubesides A-D (1-4), were isolated from the stems of Physalis pubescens L. Their structures were elucidated primarily by NMR experiments. The absolute configurations of 1 and 2 were deduced by single-crystal X-ray diffraction and ECD data analysis, respectively. Compound 3 has shown significant inhibitory activity against LPS-induced nitric oxide production in RAW 264.7 macrophages with an IC₅₀ value of 12.8 μM and moderate cytostatic activity against human carcinoma cells (786-O, C4-2B, 22Rvl, A375 and A375S2) with IC₅₀ values in the range of 3.05-9.47 μM. Molecular docking simulation demonstrated that 3 is bound in the inducible nitric oxide synthase (iNOS) active site heme pocket very well, which suggests that 3 might be a candidate for the development of iNOS inhibitors.

A natural inhibitor of kidney-type glutaminase: a withanolide from Physalis pubescens with potent anti-tumor activity

Kidney-type glutaminase (KGA), a mitochondrial enzyme converting glutamine to glutamate for energy supply, was over-expressed in many cancers and had been regarded as a promising therapeutic target in recent years. Structure-based virtual ligand screening predicted physapubescin K, a new withanolide from Physalis pubescens, to be potential KGA inhibitor. Enzyme activity inhibition assays and microscale thermophoresis experiments had demonstrated the efficiency and specificity of physapubescin K targeting KGA. Additionally, physapubescin K exhibited potent proliferation inhibitory effects on a panel of human cancer cell lines, such as SW1990 and HCC827-ER. It blocked glutamine metabolism in SW1990 with increasing intracellular level of glutamine and decreasing glutamate and its downstream metabolites. Physapubescin K also significantly inhibited the tumor growth in a SW1990 xenograft mouse model. Interestingly, physapubescin K could reverse the resistance of HCC827-ER cells to erlotinib and synergize with the hexokinase 2 inhibitor to markedly enhance the inhibition of SW1990 cell proliferation.

Oncogenic miR-23a-5p is associated with cellular function in RCC

In recent years, accumulating evidence has demonstrated that microRNAs (miRs, miRNAs) may serve an important role in the occurrence and development of tumors. miR‑23a‑5p has been confirmed as an oncogene in numerous diseases through gene chip analysis. However, as the most common type of renal tumor, the expression and function of miR‑23a‑5p in renal cell carcinoma (RCC) remains unclear. In the present study, reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) analysis, and Cell Counting Kit‑8 (CCK‑8), wound scratch, Transwell, MTT and flow cytometry assays were performed to investigate the role of miR‑23a‑5p in RCC. The expression of miR‑23a‑5p in RCC tissue samples was significantly higher compared with that in normal tissue samples (P<0.01). Furthermore, the expression of miR‑23a‑5p in RCC cell lines (786O, ACHN and Caki‑1) was significantly higher compared with that in the human embryo kidney 293T cell line, as determined using RT‑qPCR (P<0.001). In addition, the results revealed that the upregulation of miR‑23a‑5p promoted the proliferation, migration and invasion of RCC cells, and inhibited RCC cell apoptosis. The downregulation of miR‑23a‑5p resulted in the reversal of the results described above. Additionally, it was observed that the downregulation of miR‑23a‑5p significantly promoted ACHN and 786O cell viability (P<0.001). The results of the present study suggest that miR-23a-5p is an oncogene in the occurrence and development of RCC and may be a novel therapeutic target for RCC.

Importance of ROS-mediated autophagy in determining apoptotic cell death induced by physapubescin B

Physapubescin B, a steroidal compound extracted from the plant Physalis pubescens L. (Solanaceae), has been reported to possess anti-cancer potential, whereas the molecular mechanism remains elusive. In this study, we first demonstrated that physapubescin B induced autophagy in human cancer cells based on the evidence that physapubescin B increased lipidation of microtubule-associated protein 1 light chain 3 (LC3) as well as number of GFP-LC3 puncta. We further examined the molecular mechanisms and found that physapubescin B enhanced the autophagic flux through promotion of reactive oxygen species (ROS)-mediated suppression of mammalian target of rapamycin complex I (mTORC1), the key negative regulator of autophagy. Additionally, excessive ROS caused by physapubescin B also induced p53-dependent apoptotic cell death. Furthermore, we provided evidence that inhibition of autophagy either by a chemical inhibitor or gene silencing promoted physapubescin B-induced apoptotic cell death, indicating that autophagy serves as a cell survival mechanism to protect cell death. Thus, our data provide a clue that inhibition of autophagy would serve as a novel strategy for enhancing the anti-cancer potential of physapubescin B.

Stereo- and region-specific biotransformation of physapubescin by four fungal strains

Biotransformations of physapubescin (1) were performed by four fungal strains-Mucor subtilissimus AS 3.2454, Mucor polymorphosporus AS 3.3443, Aspergillus niger AS 3.795, and Syncephalastrum racemosum AS 3.264. Four metabolites were prepared in the biotransformation process of 1, and their structures were elucidated as 15α-acetoxy-5,6β:22,26:24,25-triepoxy-26α-hydroxy-3β-methoxy 4β-hydroxyergost-1-one (2), 15α-acetoxy-5,6β:22,26-diepoxy-4β,24β,25α,26(α, β)-tetrahydroxyergost-3β-methoxy-1-one (3a/3b), 15α-acetoxy-5,6β:22,26-diepoxy-4β,24β,25α,26(α, β)-tetrahydroxyergost-2-en-1-one (4a/4b), and physapubescin D (5), by spectroscopic data analysis. Among them, metabolites 2 and 3 are new. All of these fungal strains showed the ability to be highly stereo- and region-specific for the bioconversion of substrate (1). Our research provides a reference for the structural derivatization of withanolides or possibly even other natural products.