Inhibition of leptin and leptin receptor gene expression by silibinin-curcumin combination

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  Department of Medical Biotechnology, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran E-mail : nejatik@tbzmed.ac.ir, akbarzadehab@tbzmed.ac.ir.
  

Leptin and its receptor are involved in breast carcinogenesis as mitogenic factors. Therefore, they could be considered as targets for breast cancer therapy. Expression of the leptin receptor gene could be modulated by leptin secretion. Silibinin and curcumin are herbal compounds with anti-cancer activity against breast cancer. The aim of this study was to assess their potential to inhibit of expression of the leptin gene and its receptor and leptin secretion. Cytotoxic effects of the two agents on combination on T47D breast cancer cells was investigated by MTT assay test after 24h treatment. With different concentrations the levels of leptin, leptin receptor genes expression were measured by reverse-transcription real-time PCR. Amount of secreted leptin in the culture medium was determined by ELISA. Data were statistically analyzed by one-way ANOVA test. The silibinin and curcumin combination inhibited growth of T47D cells in a dose dependent manner. There were also significant difference between control and treated cells in leptin expression and the quantity of secreted leptin with a relative decrease in leptin receptor expression. In conclusion, these herbal compounds inhibit the expression and secretion of leptin and it could probably be used as drug candidates for breast cancer therapy through leptin targeting in the future.

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  Greenebaum Cancer Center, University of Maryland School of Medicine.
  

Cancer stem-like cells (CSC) and circulating tumor cells (CTCs) have related properties associated with distant metastasis, but the mechanisms through which CSCs promote metastasis are unclear. In this study, we report that breast cancer cell lines with more stem-like properties display higher levels of microtentacles (McTNs), a type of tubulin-based protrusion of the plasma cell membrane which forms on detached or suspended cells and aid in cell reattachment. We hypothesized that CSCs with large numbers of McTNs would more efficiently attach to distant tissues, promoting metastatic efficiency. The naturally occurring stem-like subpopulation of the HMLE breast cell line presents increased McTNs compared to its isogenic non-stem-like subpopulation. This increase was supported by elevated α-tubulin detyrosination and vimentin protein levels and organization. Increased McTNs in stem-like HMLEs promoted a faster initial reattachment of suspended cells that was inhibited by the tubulin-directed drug, colchicine, confirming a functional role for McTN in stem cell reattachment. Moreover, live cell confocal microscopy showed that McTN persist in breast stem cell mammospheres as flexible, motile protrusions on the surface of the mammosphere. While exposed to the environment, they also function as extensions between adjacent cells along cell-cell junctions. We found that treatment with the breast CSC-targeting compound curcumin rapidly extinguished McTN in breast CSC, preventing reattachment from suspension. Together, our results support a model in which breast CSCs with cytoskeletal alterations that promote McTN can mediate attachment and metastasis but might be targeted by curcumin as an anti-metastatic strategy.

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  Department of Experimental Surgery, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105AZ Amsterdam, The Netherlands. m.heger@amc.uva.nl.
  

This review addresses the oncopharmacological properties of curcumin at the molecular level. First, the interactions between curcumin and its molecular targets are addressed on the basis of curcumin's distinct chemical properties, which include H-bond donating and accepting capacity of the β-dicarbonyl moiety and the phenylic hydroxyl groups, H-bond accepting capacity of the methoxy ethers, multivalent metal and nonmetal cation binding properties, high partition coefficient, rotamerization around multiple C-C bonds, and the ability to act as a Michael acceptor. Next, the in vitro chemical stability of curcumin is elaborated in the context of its susceptibility to photochemical and chemical modification and degradation (e.g., alkaline hydrolysis). Specific modification and degradatory pathways are provided, which mainly entail radical-based intermediates, and the in vitro catabolites are identified. The implications of curcumin's (photo)chemical instability are addressed in light of pharmaceutical curcumin preparations, the use of curcumin analogues, and implementation of nanoparticulate drug delivery systems. Furthermore, the pharmacokinetics of curcumin and its most important degradation products are detailed in light of curcumin's poor bioavailability. Particular emphasis is placed on xenobiotic phase I and II metabolism as well as excretion of curcumin in the intestines (first pass), the liver (second pass), and other organs in addition to the pharmacokinetics of curcumin metabolites and their systemic clearance. Lastly, a summary is provided of the clinical pharmacodynamics of curcumin followed by a detailed account of curcumin's direct molecular targets, whereby the phenotypical/biological changes induced in cancer cells upon completion of the curcumin-triggered signaling cascade(s) are addressed in the framework of the hallmarks of cancer. The direct molecular targets include the ErbB family of receptors, protein kinase C, enzymes involved in prostaglandin synthesis, vitamin D receptor, and DNA.

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  ¹Université de Lorraine, Laboratoire d'ingénierie des Biomolecules, EA 4367, France.
  
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  ²Université de Lorraine, CRAN, UMR 7039, Campus Sciences, BP 70239, Vandœuvre-lès-Nancy Cedex 54506, France; CNRS, CRAN, UMR 7039, Vandœuvre-lès-Nancy, France.
  
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  ³Université de Lorraine, CRAN, UMR 7039, Campus Sciences, BP 70239, Vandœuvre-lès-Nancy Cedex 54506, France; CNRS, CRAN, UMR 7039, Vandœuvre-lès-Nancy, France; CNRS, GdR 3049 "Médicaments Photoactivables - Photochimiothérapie (PHOTOMED)", France; Centre Alexis Vautrin, CRLCC, Avenue de Bourgogne, Vandœuvre-lès-Nancy Cedex 54519, France.
  
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  ⁴Aix-Marseille Univ, LBA, F-13916 Marseille, France; IFSTTAR, LBA, F-13916 Marseille, France.
  
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  ⁵Department of Chemical Engineering, SWNG Engineering Center, Rm 2C02, University of South Carolina, 301 South Main Street, Columbia, SC 29208, United States.
  
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  ⁶Université de Lorraine, Laboratoire d'ingénierie des Biomolecules, EA 4367, France. Electronic address: elmira.arab-tehrany@univ-lorraine.fr.
  

The role of curcumin (diferuloylmethane), for cancer treatment has been an area of growing interest. However, due to its low absorption, the poor bioavailability of curcumin limits its clinical use. In this study, we reported an approach of encapsulation a curcumin by nanoliposome to achieve an improved bioavailability of a poorly absorbed hydrophobic compound. We demonstrated that liposomal preparations to deliver curcumin increase its bioavailability. Liposomes composed of salmon's lecithin also improved curcumin bioavailability compared to those constituted of rapeseed and soya lecithins. A real-time label-free cell analysis system based on real-time cell impedance monitoring was used to investigate the in vitro cytotoxicity of liposomal preparations.

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  ¹Institute for Clinical and Experimental Surgery, University of Saarland, Homburg/Saar, Germany ; Department of Internal Medicine, Division of Immunotherapy and Gene Therapy, Saarland University Medical Center, Homburg/Saar, Germany.
  
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  ²Institute for Human Genetics, University of Saarland, Homburg/Saar, Germany.
  
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  ³Institute for Clinical and Experimental Surgery, University of Saarland, Homburg/Saar, Germany.
  
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  ⁴Department for Internal Medicine - Hematology/Oncology, St. Lukas Klinik, Solingen, Germany ; Department of Internal Medicine, Division of Immunotherapy and Gene Therapy, Saarland University Medical Center, Homburg/Saar, Germany.
  

Melanoma is the most aggressive form of skin cancer with estimated 48,000 deaths per year worldwide. The polyphenol curcumin derived from the plant Curcuma longa is well known for its anti-inflammatory and anti-cancerogenic properties. Accordingly, dietary intake of this compound may be suitable for melanoma prevention. However, how this compound affects basic cellular mechanisms in developing melanoma still remains elusive. Therefore, the aim of this study was to investigate for the first time the impact of oral curcumin administration on the miRNA signature of engrafting melanoma. For this purpose, the effects of a 4% curcumin diet were tested on melanoma, which were established by injection of murine B78H1 cells in the flank of C57BL/6 mice. Curcumin diet or standard chow (control) was administered two weeks prior to injection of tumor cells until termination of the experiment. High throughput chip-based array analysis was deployed to detect alterations in the miRNA signature of the tumors. Curcumin treatment significantly reduced the growth of the flank tumors. Furthermore the miRNA expression signature in tumors was substantially altered by curcumin intake with mmu-miR-205-5p over 100 times higher expressed when compared to controls. The expression levels of identified key miRNAs in the tumor samples were confirmed by quantitative real-time polymerase chain reaction (qRT-PCR). A comparable expression pattern of these miRNAs was also detected in other curcumin-treated melanoma cell lines under in vitro conditions. Putative targets of curcumin-induced up-regulated miRNAs were enriched in 'o-glycan biosynthesis', 'endoplasmatic reticulum protein processing' and different cancer-related pathways. Western Blot analyses revealed that of these targets anti-apoptotic B-cell CLL/lymphoma 2 (Bcl-2) and proliferating cell nuclear antigen (PCNA) were significantly down-regulated in curcumin-treated tumors. These findings demonstrate a profound alteration of the miRNA expression signature in engrafting curcumin-treated melanoma with mmu-miR-205-5p being up-regulated most significantly.

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  ¹Department of Urology, Urology Research Center, College of Medicine, University of Toledo, Toledo, OH 43614, USA.
  
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  ²Department of Urology, Urology Research Center, College of Medicine, University of Toledo, Toledo, OH 43614, USA ; Protein Research Chair, Department of Biochemistry, College of Sciences, King Saud University, Riyadh 11451, Kingdom of Saudi Arabia ; Department of Clinical Nutrition, Medical University of Gdańsk, Gdańsk 80-211, Poland.