d-3-Deoxy-dioctanoylphosphatidylinositol induces cytotoxicity in human MCF-7 breast cancer cells via a mechanism that involves downregulation of the D-type cyclin-retinoblastoma pathway

Anti-Inflammatory (M2) Response Is Induced by a sp2-Iminosugar Glycolipid Sulfoxide in Diabetic Retinopathy

Diabetic retinopathy (DR) is one of the most common complications of Diabetes Mellitus (DM) and is directly associated with inflammatory processes. Currently, neuro-inflammation is considered an early event in DR and proceeds via microglia polarization. A hallmark of DR is the presence of retinal reactive gliosis. Here we report the beneficial effect of (S_S,1R)-1-docecylsulfiny-5N,6O-oxomethylidenenojirimycin ((Ss)-DS-ONJ), a member of the sp²-iminosugar glycolipid (sp²-IGL) family, by decreasing iNOS and inflammasome activation in Bv.2 microglial cells exposed to pro-inflammatory stimuli. Moreover, pretreatment with (Ss)-DS-ONJ increased Heme-oxygenase (HO)-1 as well as interleukin 10 (IL10) expression in LPS-stimulated microglial cells, thereby promoting M2 (anti-inflammatory) response by the induction of Arginase-1. The results strongly suggest that this is the likely molecular mechanism involved in the anti-inflammatory effects of (S_S)-DS-ONJ in microglia. (S_S)-DS-ONJ further reduced gliosis in retinal explants from type 1 diabetic BB rats, which is consistent with the enhanced M2 response. In conclusion, targeting microglia polarization dynamics in M2 status by compounds with anti-inflammatory activities offers promising therapeutic interventions at early stages of DR.

Synthesis of polyfluoroalkyl sp2-iminosugar glycolipids and evaluation of their immunomodulatory properties towards anti-tumor, anti-leishmanial and anti-inflammatory therapies

Immunomodulatory glycolipids, among which α-galactosylceramide (KRN7000) is an iconic example, have shown strong therapeutic potential in a variety of conditions ranging from cancer and infection to autoimmune or neurodegenerative diseases. A main difficulty for those channels is that they often provoke a cytokine storm comprising both pro- and anti-inflammatory mediators that antagonize each other and negatively affect the immune response. The synthesis of analogues with narrower cytokine secretion-inducing capabilities is hampered by the intrinsic difficulty at controlling the stereochemical outcome in glycosidation reactions, particularly if targeting the α-anomer, which seriously hampers drug optimization strategies. Here we show that replacing the monosaccharide glycone by a sp²-iminosugar glycomimetic moiety allows accessing N-linked sp²-iminosugar glycolipids (sp²-IGLs) with total α-stereocontrol in a single step with no need of protecting groups or glycosidation promotors. The lipid tail has been then readily tailored by incorporating polyfluoroalkyl segments of varied lengths in view of favouring binding to the lipid binding site of the master p38 mitogen activated protein kinase (p38 MAPK), thereby polarizing the immune response in a cell-context dependent manner. The compounds have been evaluated for their antiproliferative, anti-leishmanial and anti-inflammatory activities in different cell assays. The size of the fluorous segment was found to be critical for the biological activity, probably by regulating the aggregation and membrane-crossing properties, whereas the hydroxylation profile (gluco or galacto-like) was less relevant. Biochemical and computational data further support a mechanism of action implying binding to the allosteric lipid binding site of p38 MAPK and subsequent activation of the noncanonical autophosphorylation route. The ensemble of results provide a proof of concept of the potential of sp²-IGLs as immunoregulators.

Inositol-C2-PAF acts as a biological response modifier and antagonizes cancer-relevant processes in mammary carcinoma cells

PURPOSE

Previous studies have identified alkyl-phospholipids as promising compounds for cancer therapy by targeting constituents of the cell membrane and different signaling pathways. We previously showed that the alkylphospholipid Inositol-C2-PAF inhibits the proliferation and migration of immortalized keratinocytes and the squamous carcinoma-derived cell line SCC-25. Here, we investigated the effect of this compound on growth and motility as well as its mode of action in mammary carcinoma-derived cell lines.

METHODS

Using BrdU incorporation and haptotactic cell migration assays, we assessed the effects of Inositol-C2-PAF on MCF-7 and MBA-MB-231 cell proliferation and migration. The phosphorylation status of signaling molecules was investigated by Western blotting as well as indirect immunofluorescence analysis and capillary isoelectric focusing.

RESULTS

We found that Inositol-C2-PAF inhibited the growth as well as the migration in MCF-7 and MBA-MB-231 cells. Furthermore, we found that this compound inhibited phosphorylation of the protein kinase Akt at serine residue 473, but had no impact on phosphorylation at threonine 308. Phosphorylation of other kinases, such as Erk1/2, FAK and Src, which are targeted by Inositol-C2-PAF in other cells, remained unaffected by the compound in the mammary carcinoma-derived cell lines tested. In MCF-7 cells, we found that IGF-1-induced growth, as well as phosphorylation of Akt^S473, mTOR and the tumor suppressor pRB, was inhibited in the presence of Inositol-C2-PAF. Moreover, we found that in these cells IGF-1 had no impact on migration and did not seem to be linked to full Akt activity. Therefore, MCF-7 cell migration appears to be inhibited by Ino-C2-PAF in an Akt-independent manner.

CONCLUSION

The antagonistic effects of Inositol-C2-PAF on cell migration and proliferation are indicative for its potential for breast cancer therapy, alone or in combination with other cytostatic drugs.

The sp2-iminosugar glycolipid 1-dodecylsulfonyl-5N,6O-oxomethylidenenojirimycin (DSO2-ONJ) as selective anti-inflammatory agent by modulation of hemeoxygenase-1 in Bv.2 microglial cells and retinal explants

Neuroinflammation is an early event during diabetic retinopathy (DR) that impacts the dynamics of microglia polarization. Gliosis is a hallmark of DR and we have reported the beneficial effects of 1R-DSO-ONJ, a member of the sp²-iminosugar glycolipid (sp²-IGL) family, in targeting microglia and reducing gliosis in diabetic db/db mice. Herein, we analyzed the effect of DSO₂-ONJ, another family compound incorporating a sulfone group that better mimics the phosphate group of phosphatidylinositol ether lipid analogues (PIAs), in Bv.2 microglial cells treated with bacterial lipopolysaccaride (LPS) and in retinal explants from db/db mice. In addition to decreasing iNOS and inflammasome activation, the anti-inflammatory effect of DSO₂-ONJ was mediated by direct p38α MAPK activation. Computational docking experiments demonstrated that DSO₂-ONJ binds to p38α MAPK at the same site where PIAs and the alkyl phospholipid perifosine activators do, suggesting similar mechanism of action. Moreover, treatment of microglial cells with DSO₂-ONJ increased both heme-oxygenase (HO)-1 and Il10 expression regardless the presence of LPS. In retinal explants from db/db mice, DSO₂-ONJ also induced HO-1 and reduced gliosis. Since IL-10-mediated induction of HO-1 expression is mediated by p38α MAPK activation, our results suggest that this molecular mechanism is involved in the anti-inflammatory effects of DSO₂-ONJ in microglia.