Curcumin for the prevention of progression in monoclonal gammopathy of undetermined significance: A word of caution

The Preventive Mechanisms of Bioactive Food Compounds against Obesity-Induced Inflammation

Dietary patterns are promising strategies for preventing and treating obesity and its coexisting inflammatory processes. Bioactive food compounds have received considerable attention due to their actions against obesity-induced inflammation, with limited harmful side effects. They are perceived as food ingredients or dietary supplements other than those necessary to meet basic human nutritional needs and are responsible for positive changes in the state of health. These include polyphenols, unsaturated fatty acids, and probiotics. Although the exact mechanisms of bioactive food compounds' action are still poorly understood, studies have indicated that they involve the modulation of the secretion of proinflammatory cytokines, adipokines, and hormones; regulate gene expression in adipose tissue; and modify the signaling pathways responsible for the inflammatory response. Targeting the consumption and/or supplementation of foods with anti-inflammatory potential may represent a new approach to obesity-induced inflammation treatment. Nevertheless, more studies are needed to evaluate strategies for bioactive food compound intake, especially times and doses. Moreover, worldwide education about the advantages of bioactive food compound consumption is warranted to limit the consequences of unhealthy dietary patterns. This work presents a review and synthesis of recent data on the preventive mechanisms of bioactive food compounds in the context of obesity-induced inflammation.

Overweight/Obesity and Monoclonal Gammopathy of Undetermined Significance

BACKGROUND

Obesity and high body mass index (BMI) are associated with increased incidence of multiple myeloma (MM). MM usually evolves from a precursor asymptomatic disease, namely monoclonal gammopathy of undetermined significance (MGUS). MGUS progresses to MM at a 1% annual rate; however, risk factors predisposing to MGUS are not completely understood. We conducted a systematic review to assess the relationship between obesity and high BMI with MGUS prevalence and progression to MM. To our knowledge, this is the first systematic review evaluating the role of obesity in MGUS.

PATIENTS AND METHODS

We searched the Medline database and ClinicalTrials.gov for studies investigating BMI and obesity association with MGUS incidence and progression. The algorithm consisted of a predefined combination of the words "obesity," "obese," "body mass index," "overweight," "diet," "nutrition," "food," "dietary," "adiponectin," "monoclonal gammopathy," and "MGUS".

RESULTS

Overall, 12 articles were retrieved, including 11 eligible articles and 1 clinical trial. More than 57,068 patients were evaluated in this systematic review. Discrepancies between the identified studies were noted. Multiple studies support the notion that obesity or high BMI are positively linked to MGUS prevalence and transition to MM. In contrast, other studies revealed no such association. Visceral adipose tissue metabolic activity and decreased adiponectin concentrations were identified as biomarkers of MGUS progression to MM.

CONCLUSION

Obesity and increased BMI seem to be implicated both in MGUS development and progression to MM. Further studies should be designed to confirm this hypothesis.

Modulation of adipose tissue inflammation by bioactive food compounds

Adipose tissue has an important endocrine function in the regulation of whole-body metabolism. Obesity leads to a chronic low-grade inflammation of the adipose tissue, which disrupts this endocrine function and results in metabolic derangements, such as type-2 diabetes. Dietary bioactive compounds, such as polyphenols and certain fatty acids, are known to suppress both systemic and adipose tissue inflammation and have the potential to improve these obesity-associated metabolic disorders. Mechanistically, polyphenolic compounds including non-flavonoids, such as curcumin and resveratrol, and flavonoids, such as catechins (tea-polyphenols), quercetin and isoflavones, suppress nuclear factor-κB (NF-κB) and mitogen-activated protein (MAP) kinases (MAPK) pathways while activating the 5' adenosine monophosphate-activated protein kinase (AMPK) pathway in adipose tissue. Dietary polyunsaturated fatty acids, such as eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), conjugated linoleic acid (CLA) and monounsaturated fatty acids (MUFA), such as oleic acid, also impart anti-inflammatory effects through several mechanisms. These include activation of AMPK and peroxisome proliferator-activated receptor gamma (PPAR-γ), as well as suppression of toll-like receptors (TLRs) and NF-κB pathway. This review discusses the major molecular mechanisms of dietary polyphenols and fatty acids, alone or in combination, which are responsible for adipose tissue-associated anti-inflammatory effects.

Curcumin affects proprotein convertase activity: elucidation of the molecular and subcellular mechanism

Proprotein convertases (PCs) form a group of serine endoproteases that are essential for the activation of proproteins into their active form. Some PCs have been proposed to be potential therapeutic targets for cancer intervention because elevated PC activity has been observed in many different cancer types and because many of the PC substrates, such as pro-IGF-1R, pro-TGF-beta, pro-VEGF, are involved in signaling pathways related to tumor development. Curcumin, reported to possess anticancer activity, also affects many of these pathways. We therefore investigated the effect of curcumin on PC activity. Our results show that curcumin inhibits PC activity in a cell lysate-based assay but not in vitro. PC zymogen maturation in the endoplasmic reticulum appears to be inhibited by curcumin. Treating cells with thapsigargin or cyclopiazonic acid, two structurally unrelated inhibitors of the sarco- and endoplasmic reticulum Ca(2+)ATPase (SERCA), also hampered both the PC zymogen maturation and the PC activity. Importantly, curcumin, like the SERCA inhibitors, impaired ATP-driven (45)Ca(2+) uptake in the endoplasmic reticulum. These results indicate that curcumin likely restrains PC activity by inhibiting SERCA-mediated Ca(2+)-uptake activity. Experiments in three colon cancer cell lines confirm that curcumin inhibits both the (45)Ca(2+) uptake and PC activity, notably the processing of pro-IGF-1R. Both curcumin and thapsigargin inhibit the anchorage-independent growth of these three colon carcinoma cell lines. In conclusion, our findings indicate that curcumin inhibits PC zymogen maturation and consequently PC activity and that its inhibitory effect on Ca(2+) uptake into the ER allows and is sufficient to explain this phenomenon.

Ganoderma lucidum polysaccharides counteract inhibition on CD71 and FasL expression by culture supernatant of B16F10 cells upon lymphocyte activation

Immune responses to tumor-associated antigens are often detectable in tumor-bearing hosts, but they fail to eliminate malignant cells or prevent development of metastases. Tumor cells produce factors such as interleukin-10, transforming growth factor-β1 and vascular endothelial growth factor (VEGF) that suppress the function of immune cells or induce apoptosis of immune cells. Culture supernatant of tumor cells may contain these immunosuppressive factors which suppress lymphocyte activation. CD71 and FasL are two important molecules that are expressed upon lymphocyte activation. Counteraction against suppression CD71 and FasL expression upon lymphocyte activation may benefit tumor control. A potential component with this effect is Ganoderma lucidum polysaccharides (Gl-PS). In this study, Gl-PS was used on lymphocytes incubating with culture supernatant of B16F10 melanoma cells (B16F10-CS) in the presence of phytohemagglutinin. Following induction with phytohemagglutinin, B16F10-CS suppressed CD71 expression in lymphocytes (as detected by immunofluorescence and flow cytometry), proliferation in lymphocytes (as detected by MTT assay), and FasL expression in lymphocytes (as detected by immunocytochemistry and western blot analysis), while Gl-PS fully or partially counteracted these suppressions. Gl-PS showed counteractive effects against suppression induced by B16F10-CS on CD71 and FasL expression upon lymphocyte activation, suggesting the potential of Gl-PS to facilitate cancer immunotherapy.