Studies on β-sitosterol and ceramide-induced alterations in the properties of cholesterol/sphingomyelin/ganglioside monolayers

β-Sitosterol Inhibits Tumor Growth and Amplifies Rituximab Sensitivity through Acid Sphingomyelinase/Ceramide Signaling in Diffuse Large B-Cell Lymphoma

Rituximab (RTX) resistance is a notable challenge in treating diffuse large B-cell lymphoma (DLBCL). β-Sitosterol (β-ST) is a plant sterol that has been found in a broad variety of fruits, spices, and medicinal plants. The antineoplastic properties of β-ST are established in various solid malignancies; however, its effect on DLBCL is uncharted. This study investigates the role of β-ST in DLBCL as well as the underlying mechanisms. Our findings indicated that β-ST impeded DLBCL cell proliferation in a concentration- and time-dependent manner. β-ST appeared to alter sphingolipid metabolism, facilitate acid sphingomyelinase (ASM) translocation to the plasma membrane, augment ceramide platforms through increased ceramide synthesis, and consequently induce apoptosis in DLBCL cells. Furthermore, we found that RTX initiated both apoptotic and survival pathways in vitro, with the former contingent on the transient activation of the ASM, and β-ST could amplify the anti-DLBCL efficacy of RTX by modulating ASM/Ceramide (Cer) signaling. Collectively, our findings elucidate the mechanistic role of β-ST in DLBCL and underscore its potential in amplifying the antineoplastic efficacy of RTX via ASM activation, proposing a potential avenue to improve the efficacy of RTX therapy.

β-Sitosterol as a Promising Anticancer Agent for Chemoprevention and Chemotherapy: Mechanisms of Action and Future Prospects

Cancer is one of the primary causes of death worldwide, and its incidence continues to increase yearly. Despite significant advances in research, the search for effective and nontoxic preventive and therapeutic agents remains greatly important. Cancer is a multimodal disease, where various mechanisms play significant roles in its occurrence and progression. This highlights the need for multitargeted approaches that are not only safe and inexpensive but also provide effective alternatives for current therapeutic regimens. β-Sitosterol (SIT), the most abundant phytosterol found in various plant foods, represents such an option. Preclinical evidence over the past few decades has overwhelmingly shown that SIT exhibits multiple anticancer activities against varied cancers, such as liver, cervical, colon, stomach, breast, lung, pancreatic, and prostate cancers, in addition to leukemia, multiple myeloma, melanoma, and fibrosarcoma. In this article, we present the latest advances and perspectives on SIT-systematically summarizing its antitumor mechanisms of action into 7 main sections and combining current challenges and prospects-for its use as a promising agent for cancer prevention and treatment. In particular, SIT plays a role in cancer prevention and treatment mainly by enhancing apoptosis, inducing cell cycle arrest, bidirectionally regulating oxidative stress, improving metabolic reprogramming, inhibiting invasion and metastasis, modulating immunity and inflammation, and combating drug resistance. Although SIT holds such great promise, the poor aqueous solubility and bioavailability coupled with low targeting efficacy limit its therapeutic efficacy and clinical application. Further research on novel drug delivery systems may improve these deficiencies. Overall, through complex and pleiotropic mechanisms, SIT has good potential for tumor chemoprevention and chemotherapy. However, no clinical trials have yet proven this potential. This review provides theoretical basis and rationality for the further design and conduct of clinical trials to confirm the anticancer activity of SIT.

Alteration of cholesterol distribution at the plasma membrane of cancer cells: From evidence to pathophysiological implication and promising therapy strategy

Cholesterol-enriched domains are nowadays proposed to contribute to cancer cell proliferation, survival, death and invasion, with important implications in tumor progression. They could therefore represent promising targets for new anticancer treatment. However, although diverse strategies have been developed over the years from directly targeting cholesterol membrane content/distribution to adjusting sterol intake, all approaches present more or less substantial limitations. Those data emphasize the need to optimize current strategies, to develop new specific cholesterol-targeting anticancer drugs and/or to combine them with additional strategies targeting other lipids than cholesterol. Those objectives can only be achieved if we first decipher (i) the mechanisms that govern the formation and deformation of the different types of cholesterol-enriched domains and their interplay in healthy cells; (ii) the mechanisms behind domain deregulation in cancer; (iii) the potential generalization of observations in different types of cancer; and (iv) the specificity of some alterations in cancer vs. non-cancer cells as promising strategy for anticancer therapy. In this review, we will discuss the current knowledge on the homeostasis, roles and membrane distribution of cholesterol in non-tumorigenic cells. We will then integrate documented alterations of cholesterol distribution in domains at the surface of cancer cells and the mechanisms behind their contribution in cancer processes. We shall finally provide an overview on the potential strategies developed to target those cholesterol-enriched domains in cancer therapy.

Exploring the biophysical properties of phytosterols in the plasma membrane for novel cancer prevention strategies

Cancer is a global problem with no sign that incidences are reducing. The great costs associated with curing cancer, through developing novel treatments and applying patented therapies, is an increasing burden to developed and developing nations alike. These financial and societal problems will be alleviated by research efforts into prevention, or treatments that utilise off-patent or repurposed agents. Phytosterols are natural components of the diet found in an array of seeds, nuts and vegetables and have been added to several consumer food products for the management of cardio-vascular disease through their ability to lower LDL-cholesterol levels. In this review, we provide a connected view between the fields of structural biophysics and cellular and molecular biology to evaluate the growing evidence that phytosterols impair oncogenic pathways in a range of cancer types. The current state of understanding of how phytosterols alter the biophysical properties of plasma membrane is described, and the potential for phytosterols to be repurposed from cardio-vascular to oncology therapeutics. Through an overview of the types of biophysical and molecular biology experiments that have been performed to date, this review informs the reader of the molecular and biophysical mechanisms through which phytosterols could have anti-cancer properties via their interactions with the plasma cell membrane. We also outline emerging and under-explored areas such as computational modelling, improved biomimetic membranes and ex vivo tissue evaluation. Focus of future research in these areas should improve understanding, not just of phytosterols in cancer cell biology but also to give insights into the interaction between the plasma membrane and the genome. These fields are increasingly providing meaningful biological and clinical data but iterative experiments between molecular biology assays, biosynthetic membrane studies and computational membrane modelling improve and refine our understanding of the role of different sterol components of the plasma membrane.

Applications of Brewster angle microscopy from biological materials to biological systems

Brewster angle microscopy (BAM) is a powerful technique that allows for real-time visualization of Langmuir monolayers. The lateral organization of these films can be investigated, including phase separation and the formation of domains, which may be of different sizes and shapes depending on the properties of the monolayer. Different molecules or small changes within a molecule such as the molecule's length or presence of a double bond can alter the monolayer's lateral organization that is usually undetected using surface pressure-area isotherms. The effect of such changes can be clearly observed using BAM in real-time, under full hydration, which is an experimental advantage in many cases. While previous BAM reviews focused more on selected compounds or compared the impact of structural variations on the lateral domain formation, this review provided a broader overview of BAM application using biological materials and systems including the visualization of amphiphilic molecules, proteins, drugs, extracts, DNA, and nanoparticles at the air-water interface.

β-Sitosterol Reduces the Expression of Chemotactic Cytokine Genes in Cystic Fibrosis Bronchial Epithelial Cells

Extracts from Nigella arvensis L. seeds, which are widely used as anti-inflammatory remedies in traditional medicine of Northern Africa, were able to inhibit the expression of the pro-inflammatory neutrophil chemokine Interleukin (IL)-8 in Cystic Fibrosis (CF) bronchial epithelial IB3-1 cells exposed to the Gram-negative bacterium Pseudomonas aeruginosa. The chemical composition of the extracts led to the identification of three major components, β-sitosterol, stigmasterol, and campesterol, which are the most abundant phytosterols, cholesterol-like molecules, usually found in plants. β-sitosterol (BSS) was the only compound that significantly reproduced the inhibition of the P. aeruginosa-dependent expression of IL-8 at nanomolar concentrations. BSS was tested in CF airway epithelial CuFi-1 cells infected with P. aeruginosa. BSS (100 nM), showed a significant and consistent inhibitory activity on expression of the P. aeruginosa-stimulated expression chemokines IL-8, GRO-α GRO-β, which play a pivotal role in the recruitment of neutrophils in CF inflamed lungs. Preliminary mechanistic analysis showed that BSS partially inhibits the P. aeruginosa-dependent activation of Protein Kinase C isoform alpha, which is known to be involved in the transmembrane signaling activating IL-8 gene expression in bronchial epithelial cells. These data indicate BSS as a promising molecule to control excessive lung inflammation in CF patients.

Elevated serum IL-11, TNF α, and VEGF expressions contribute to the pathophysiology of hypertensive intracerebral hemorrhage (HICH)

To study the changes in serum interleukin-11 (IL-11), tumor necrosis factor-α (TNF-α) and vascular endothelial growth factor (VEGF) expressions following hypertensive intracerebral hemorrhage (HICH), and explore their associations with disease severity and prognosis. Serum IL-11, TNF-α, and VEGF levels after 1, 3, 7, and 14 days after HICH were assayed using enzyme-linked immunosorbent assay (ELISA), and neurological deficit score (NDS) were recorded at admission and discharge for 99 HICH cases. Then 45 healthy controls were included and assayed for serum IL-11, TNF-α, and VEGF levels. Serum IL-11, TNF-α, and VEGF levels were higher in HICH patients than healthy controls (all P < 0.05). TNF-α was higher at the 3rd day following disease onset than other time points (all P < 0.05), while IL-11 and VEGF peaked at the 7th day and dropped below baseline values at the 14th day (all P < 0.05). Serum IL-11 was positively correlated with TNF-α (r = 0.70, P < 0.05) and VEGF (r = 0.72, P < 0.05). Serum TNF-α was positively correlated with VEGF (r = 0.46, P < 0.05). Serum IL-11, TNF-α, and VEGF were associated with disease severity in HICH patients. Patients with more severe disease tended to have higher NDS at admission, and higher IL-11, TNF-α, and VEGF during treatment were associated with higher NDS at discharge. Serum IL-11, TNF-α, and VEGF may involve in the pathophysiology of HICH, thus IL-11, TNF-α, and VEGF may be prognostic factors for post HICH neurologic damage.

Dietary walnut suppression of colorectal cancer in mice: Mediation by miRNA patterns and fatty acid incorporation

Colorectal cancer, unlike many other malignancies, may be preventable. Recent studies have demonstrated an inverse association between nut consumption and incidence of colon cancer; however, the underlying mechanisms are not fully understood. An emerging concept suggests that microribonucleic acids (miRNAs) may help explain the relationship between walnut consumption and decreased colorectal neoplasia risk. Seven days after HT-29 colon cancer cell injection, mice were randomized to either control or walnut diets for 25 days of diet treatment. Thirty samples of tumor and of omental adipose were analyzed to determine changes in lipid composition in each dietary group. In the tumors of the walnut-containing diet, we found significant increases in α-linolenic, eicosapentaenoic, docosahexaenoic and total omega-3 acids, and a decrease in arachidonic acid, as compared to the control diet. Final tumor size measured at sacrifice was negatively associated with percentage of total omega-3 fatty acid composition (r=-0.641, P=.001). MicroRNA expression analysis of colorectal tumor tissue revealed decreased expression of miRNAs 1903, 467c and 3068 (P<.05) and increased expression of miRNA 297a* (P=.0059) in the walnut-treated group as compared to control diet. Our results indicate that changes in the miRNA expression profiles likely affect target gene transcripts involved in pathways of anti-inflammation, antivascularization, antiproliferation and apoptosis. We also demonstrate the incorporation of protective fatty acids into colonic epithelium of walnut-fed mice, which may independently alter miRNA expression profiles itself. Future studies of the mechanism of widespread miRNA regulation by walnut consumption are needed to offer potential prognostic and therapeutic targets.

Phytochemical profile of Paulownia tomentosa (Thunb). Steud

Paulownia tomentosa, a member of the plant family Paulowniaceae and a rich source of biologically active secondary metabolites, is traditionally used in Chinese herbal medicine. Flavonoids, lignans, phenolic glycosides, quinones, terpenoids, glycerides, phenolic acids, and miscellaneous other compounds have been isolated from different parts of P. tomentosa plant. Recent interest in this species has focused on isolating and identifying of prenylated flavonoids, that exhibit potent antioxidant, antibacterial, and antiphlogistic activities and inhibit severe acute respiratory syndrome coronavirus papain-like protease. They show cytotoxic activity against various human cancer cell lines and inhibit the effects of human cholinesterase, butyrylcholinesterase, and bacterial neuraminidases. Most of the compounds considered here have never been isolated from any other species of plant. This review summarizes the information about the isolated compounds that are active, their bioactivities, and the structure-activity relationships that have been worked out for them.

Walnuts have potential for cancer prevention and treatment in mice

Cancer may not be completely the result of novel or inherited genetic mutations but may in fact be a largely preventable disease. Researchers have identified biochemicals, including n-3 (ω-3) fatty acids, tocopherols, β-sitosterol, and pedunculagin, that are found in walnuts and that have cancer-prevention properties. Mouse studies in which walnuts were added to the diet have shown the following compared with the control diet: (1) the walnut-containing diet inhibited the growth rate of human breast cancers implanted in nude mice by ∼80%; (2) the walnut-containing diet reduced the number of mammary gland tumors by ∼60% in a transgenic mouse model; (3) the reduction in mammary gland tumors was greater with whole walnuts than with a diet containing the same amount of n-3 fatty acids, supporting the idea that multiple components in walnuts additively or synergistically contribute to cancer suppression; and (4) walnuts slowed the growth of prostate, colon, and renal cancers by antiproliferative and antiangiogenic mechanisms. Cell studies have aided in the identification of the active components in walnuts and of their mechanisms of action. This review summarizes these studies and presents the notion that walnuts may be included as a cancer-preventive choice in a healthy diet.

Membrane composition and dynamics: a target of bioactive virgin olive oil constituents

The endogenous synthesis of lipids, which requires suitable dietary raw materials, is critical for the formation of membrane bilayers. In eukaryotic cells, phospholipids are the predominant membrane lipids and consist of hydrophobic acyl chains attached to a hydrophilic head group. The relative balance between saturated, monounsaturated, and polyunsaturated acyl chains is required for the organization and normal function of membranes. Virgin olive oil is the richest natural dietary source of the monounsaturated lipid oleic acid and is one of the key components of the healthy Mediterranean diet. Virgin olive oil also contains a unique constellation of many other lipophilic and amphipathic constituents whose health benefits are still being discovered. The focus of this review is the latest evidence regarding the impact of oleic acid and the minor constituents of virgin olive oil on the arrangement and behavior of lipid bilayers. We highlight the relevance of these interactions to the potential use of virgin olive oil in preserving the functional properties of membranes to maintain health and in modulating membrane functions that can be altered in several pathologies. This article is part of a Special Issue entitled: Membrane Structure and Function: Relevance in the Cell's Physiology, Pathology and Therapy.