Naturally Derived Anti-HIV Polysaccharide Peptide (PSP) Triggers a Toll-Like Receptor 4-Dependent Antiviral Immune Response

Aim. Intense interest remains in the identification of compounds to reduce human immunodeficiency virus type 1 (HIV-1) replication. Coriolus versicolor’s polysaccharide peptide (PSP) has been demonstrated to possess immunomodulatory properties with the ability to activate an innate immune response through Toll-like receptor 4 (TLR4) showing insignificant toxicity. This study sought to determine the potential use of PSP as an anti-HIV agent and whether its antiviral immune response was TLR4 dependent. Materials and Methods. HIV-1 p24 and anti-HIV chemokine release was assessed in HIV-positive (HIV+) THP1 cells and validated in HIV+ peripheral blood mononuclear cells (PBMCs), to determine PSP antiviral activity. The involvement of TLR4 activation in PSP anti-HIV activity was evaluated by inhibition. Results. PSP showed a promising potential as an anti-HIV agent, by downregulating viral replication and promoting the upregulation of specific antiviral chemokines (RANTES, MIP-1α/β, and SDF-1α) known to block HIV-1 coreceptors in THP1 cells and human PBMCs. PSP produced a 61% viral inhibition after PSP treatment in HIV-1-infected THP1 cells. Additionally, PSP upregulated the expression of TLR4 and TLR4 inhibition led to countereffects in chemokine expression and HIV-1 replication. Conclusion. Taken together, these findings put forward the first evidence that PSP exerts an anti-HIV activity mediated by TLR4 and key antiviral chemokines. Elucidating these new molecular mediators may reveal additional drug targets and open novel therapeutic avenues for HIV-1 infection

The Asbestos Sheet Feb. 1960

Curcumin, an extract from the turmeric rhizome (Curcuma longa), is known to exhibit anti-inflammatory, antioxidant, chemopreventive and antitumoral activities against aggressive and recurrent cancers. Accumulative data indicate that curcumin may induce cancer cell death. However, the detailed mechanism underlying its pro-apoptotic and anti-cancer effects remains to be elucidated. In the present study, we examined the signaling pathways triggered by curcumin, specifically, the exact molecular mechanisms of curcumin-induced apoptosis in highly metastatic human prostate cancer cells. The effect of curcumin was evaluated using for the first time in prostate cancer, a gel-free shotgun quantitative proteomic analysis coupled with Tandem Mass Tag isobaric labeling-based-signaling networks. Results were confirmed at the gene expression level by qRT-PCR and at the protein expression level by western blot and flow cytometry. Our findings revealed that curcumin induced an Endoplasmic Reticulum stress-mediated apoptosis in PC3. The mechanisms by which curcumin promoted cell death in these cells were associated with cell cycle arrest, increased reactive oxygen species, autophagy and the Unfolded Protein Response. Furthermore, the upregulation of ER stress was measured using key indicators of ER stress: Glucose-Regulated Protein 78, Inositol-Requiring Enzyme 1 alpha, Protein Disulfide isomerase and Calreticulin. Chronic ER stress induction was concomitant with the upregulation of pro-apoptotic markers (caspases 3,9,12) and Poly (ADP-ribose) polymerase. The downregulated proteins include anti-apoptotic and anti-tumor markers, supporting their curcumin-induced pro-apoptotic role in prostate cancer cells. Taken together, these data suggest that curcumin may serve as a promising anticancer agent by inducing a chronic ER stress mediated cell death and activation of cell cycle arrest, UPR, autophagy and oxidative stress responses

Curcumin inhibits cell proliferation and promotes cell death.

<p>(A) Optical micrograph of PC3 confluency after treatment with either Curcumin or DMSO. (B) Percentage of death cells stained with 7AAD, analyzed by flow cytometry and compared by unpaired t-test, p≤0.05. (C) Cell cycle analysis by flow cytometry; statistical analysis was determined by Two-way ANOVA, *p≤0.05, **p≤0.01.</p

Proposed molecular mechanism of Curcumin’s cytotoxic effects in metastatic prostate cancer cells (PC3).

<p>Curcumin causes a chronic ER and oxidative stress inducing autophagy, cell cycle arrest, ERAD, cytoskeletal changes and caspase mediated apoptosis. Upward (↑) and downward (↓) arrows indicate upregulation or downregulation of proteins respectively.</p

Curcumin triggers ER stress.

<p>(A-C) Protein expression of ER stress markers: GRP78, IRE-1α and Calreticulin analyzed by western blotting. (D) Phosphorylated expression of eIF2α protein assessed by flow cytometry. Statistical significance between Curcumin and DMSO was determined by unpaired t-test, * p≤0.05, ** p≤0.01, ***p≤0.001.</p

Overexpressed proteins identified in PC3 cells treated with curcumin and arranged in decreasing fold change order.

<p>Overexpressed proteins identified in PC3 cells treated with curcumin and arranged in decreasing fold change order.</p