Herbal melanin induces interleukin-1ß secretion and production by human THP-1 monocytes via Toll-like receptor 2 and p38 MAPK activation.

Herbal melanin (HM), extracted from Nigella sativa, is known for its immunogenic properties through the modulation of cytokine production via Toll-like receptor (TLR)4. TLRs play a crucial role in the host defense through the regulation of innate and adaptive immune responses. However, the potential effect of HM on the production of interleukin-1ß (IL-1ß), the main immunoregulatory cytokine secreted by activated monocytes, has not been reported. The present study aimed to investigate the effects of HM on IL-1ß secretion and production, detected by enzyme-linked immunosorbent assay, western blotting and mRNA expression monitored by reverse transcription-PCR, in human monocytes and a monocytic cell line, THP-1. Signaling pathways involved in the HM-induced IL-1ß production was investigated in the THP-1 cells. It was shown that HM upregulated the IL-1ß mRNA in the THP-1 cells and induced the secretion of IL-1ß in the monocytes and THP-1 cells, in a dose-dependent manner, compared to the untreated cells. HM increased the protein expression of IL-1ß, TLR2, the main receptor for IL-1ß production, and activated p38 mitogen-activated protein kinase (MAPK), a key mediator for stress-induced IL-1ß gene expression. The blockade of the p38 MAPK pathway, with the pharmacological inhibitor SB202190, and TLR2 receptor with a neutralization antibody, resulted in the decrease of HM-induced IL-1ß production in THP-1 cells. The TLR4 receptor blockade also decreased HM-induced IL-1ß production, but to a lesser extent than TLR2 blockade. In conclusion, the present study demonstrated that HM stimulates IL-1ß production in monocytes and THP-1 cells, in a TLR2/p38 MAPK pathway-dependent manner, suggesting promising immunoregulatory potentials of HM against inflammatory-associated diseases.

Anti-Proliferative and Pro-Apoptotic Effects of Calligonum comosum (L'Her.) Methanolic Extract in Human Triple-Negative MDA-MB-231 Breast Cancer Cells.

Triple-negative breast cancer (TNBC), the most aggressive subtype, does not respond to targeted therapy due to the lack of hormone receptors. There is an urgent need for alternative therapies, including natural product-based anti-cancer drugs, at lower cost. We investigated the impact of a Calligonum comosum L'Hér. methanolic extract (CcME) on the TNBC MDA-MB-231 cell line proliferation and related cell death mechanisms performing cell viability and cytotoxicity assays, flow cytometry to detect apoptosis and cell cycle analysis. The apoptosis-related protein array and cellular reactive oxygen species (ROS) assay were also carried out. We showed that the CcME inhibited the TNBC cell viability, in a dose-dependent manner, with low cytotoxic effects. The CcME-treated TNBC cells underwent apoptosis, associated with a concomitant increase of apoptosis-related protein expression, including cytochrome c, cleaved caspase-3, cyclin-dependent kinase inhibitor p21, and the anti-oxidant enzyme catalase, compared with the untreated cells. The CcME also enhanced the mitochondrial transition pore opening activity and induced G0/G1 cell growth arrest, which confirmed the cytochrome c release and the increase of the p21 expression detected in the CcME-treated TNBC cells. The CcME-treated TNBC cells resulted in intracellular ROS production, which, when blocked with a ROS scavenger, did not reduce the CcME-induced apoptosis. In conclusion, CcME exerts anti-proliferative effects against TNBC cells through the induction of apoptosis and cell growth arrest. In vivo studies are justified to verify the CcME anti-proliferative activities and to investigate any potential anti-metastatic activities of CcME against TNBC development and progression.

Distinct anti-proliferative effects of herbal melanin on human acute monocytic leukemia THP-1 cells and embryonic kidney HEK293 cells.

BACKGROUND: Herbal melanin (HM) is a dark pigment extracted from the seed coat of Nigella sativa L. and known to exert biological effects via toll-like receptor 4 (TLR4). Recently, TLR4 was described as involved in natural programmed cell death (apoptosis). Tumor and embryonic cells are used as in vitro cellular models for drug and anti-cancer agent screening. To date, no cytotoxic studies have been reported of HM in TLR4-positive acute monocytic leukemia THP-1 cells compared to TLR4-negative human embryonic kidney HEK293 cells. METHODS: We studied the anti-proliferative effects of several HM concentrations on THP-1 and HEK293 cells by evaluating cell viability using the CellTiter-Glo® luminescent assay, assessing the TLR4 expression level, determining the apoptotic status, and analyzing the cell cycle distribution using flow cytometry. Apoptotic pathways were investigated using mitochondrial transition pore opening, caspase activity assays and immunoblot technology. RESULTS: Low HM concentrations did not affect THP-1 cell viability, but high HM concentrations (62.5-500 µg/mL) did decrease THP-1 cell viability and induced G0/G1 phase cell cycle arrest. Only at the highest concentration (500 µg/mL), HM slightly increased the TLR4 expression on the THP-1 cell surface, concomitantly upregulated TLR4 whole protein and gene expression, and induced apoptosis in THP-1 cells via activation of the extrinsic and intrinsic pathways. No change of apoptotic status was noticed in TLR4-negative HEK293 cells, although HM decreased HEK293 cell viability and induced cell growth arrest in the G2 phase. CONCLUSION: HM exerts distinct anti-proliferative effects on human acute monocytic leukemia and embryonic kidney cells mainly through cell cycle interference in a TLR4-independent manner and through apoptosis induction in a TLR4-dependent manner, as observed in only the THP-1 cells.

Biological impact of advanced glycation endproducts on estrogen receptor-positive MCF-7 breast cancer cells.

Diabetes mellitus potentiates the risk of breast cancer. We have previously described the pro-tumorigenic effects of advanced glycation endproducts (AGEs) on estrogen receptor (ER)-negative MDA-MB-231 breast cancer cell line mediated through the receptor for AGEs (RAGE). However, a predominant association between women with ER-positive breast cancer and type 2 diabetes mellitus has been reported. Therefore, we have investigated the biological impact of AGEs on ER-positive human breast cancer cell line MCF-7 using in vitro cell-based assays including cell count, migration, and invasion assays. Western blot, FACS analyses and quantitative real time-PCR were also performed. We found that AGEs at 50-100µg/mL increased MCF-7 cell proliferation and cell migration associated with an enhancement of pro-matrix metalloproteinase (MMP)-9 activity, without affecting their poor invasiveness. However, 200µg/mL AGEs inhibited MCF-7 cell proliferation through induction of apoptosis indicated by caspase-3 cleavage detected using Western blotting. A phospho-protein array analysis revealed that AGEs mainly induce the phosphorylation of extracellular-signal regulated kinase (ERK)1/2 and cAMP response element binding protein-1 (CREB1), both signaling molecules considered as key regulators of AGEs pro-tumorigenic effects. We also showed that AGEs up-regulate RAGE and ER expression at the protein and transcript levels in MCF-7 cells, in a RAGE-dependent manner after blockade of AGEs/RAGE interaction using neutralizing anti-RAGE antibody. Throughout the study, BSA had no effect on cellular processes. These findings pave the way for future studies investigating whether the exposure of AGEs-treated ER-positive breast cancer cells to estrogen could lead to a potentiation of breast cancer development and progression.

CD95-mediated apoptosis in Burkitt's lymphoma B-cells is associated with Pim-1 down-regulation.

B-cells of the high-grade non-Hodgkin lymphoma Burkitt's lymphoma (BL) overexpress survival oncoproteins, including the proviral integration site for Moloney murine leukaemia virus kinase (Pim)-1, and become apoptosis resistant. Activated death receptor CD95 after ligation with anti-CD95 monoclonal antibody (mAb) resulted in the regression of BL via induction of apoptosis, suggesting a decrease of survival protein expression. Here, CD95-mediated apoptotic pathways in BL B-cell lines (Raji and Daudi) following treatment with anti-CD95 mAb was investigated with the cause-and-effects on pim-1 gene expression, in comparison with leukemic cell line (K562) used as CD95-negative cells. Immunohistochemical staining for CD95 and Pim-1 was performed, and the effects of anti-CD95 mAb on apoptotic signalling using western blotting, on caspase activity and cell survival of BL B-cell and leukemic cell lines were determined. We showed that Raji cells expressed more CD95 receptors than Daudi cells. Half of each population underwent apoptosis accompanied by decreased cell viability after anti-CD95 mAb treatment. Distinct extrinsic and intrinsic CD95-mediated apoptotic pathways in Raji and Daudi cells were revealed by high caspase activity and mitochondrial outer membrane permeabilization, respectively. We observed decreased Pim-1 transcript and protein expression levels with increased heat-shock protein (Hsp)70 and decreased Hsp90 expression in anti-CD95 mAb-treated cells. Throughout the study, K562 cells did not undergo apoptosis upon anti-CD95 mAb treatment. Pim-1 knockdown following to stable transfection with plasmid vectors induced apoptosis and decreased viability of BL and K562 cells. Therefore, CD95-mediated apoptosis induces Pim-1 down-regulation in BL B-cells, but Pim-1 down-regulation cannot fully eradicate BL and leukaemia.