Ornella Pellerito

Apoptosis induced in HepG2 cells by the synthetic cannabinoid WIN: involvement of the transcription factor PPARγ.

It has recently been shown that cannabinoids induce growth inhibition and apoptosis in different tumour cell lines. In the current study, the effects of WIN 55,212-2 (WIN), a synthetic and potent cannabinoid receptor agonist, are investigated in hepatoma HepG2 cells and a possible signal transduction pathway is proposed. In these cells, WIN induces a clear apoptotic effect which was accompanied by up-regulation of the death-signalling factors Bax, Bcl-X(S), t-Bid and down-regulation of the survival factors survivin, phospho-AKT, Hsp72 and Bcl-2. Moreover, WIN-induced apoptosis is associated with JNK/p38 MAPK pathway activation and mitochondrial depolarisation demonstrated by a cytofluorimetric assay. The results also show that in HepG2 cells WIN markedly increases the level of the transcription factor PPARgamma in a dose- and time-dependent manner. The addition of the PPARgamma antagonists GW9662 and T0070907 significantly reduces the effects of the drug on both cell viability and the levels of survivin, phospho-AKT and phospho-BAD, suggesting that PPARgamma plays a key role in WIN-induced apoptosis. Altogether, the results seem to indicate a potential therapeutic role of WIN in hepatic cancer treatment.

Research paperApoptosis induced in HepG2 cells by the synthetic cannabinoid WIN: Involvement of the transcription factor PPARγ

It has recently been shown that cannabinoids induce growth inhibition and apoptosis in different tumour cell lines. In the current study, the effects of WIN 55,212-2 (WIN), a synthetic and potent cannabinoid receptor agonist, are investigated in hepatoma HepG2 cells and a possible signal transduction pathway is proposed. In these cells, WIN induces a clear apoptotic effect which was accompanied by up-regulation of the death-signalling factors Bax, Bcl-X(S), t-Bid and down-regulation of the survival factors survivin, phospho-AKT, Hsp72 and Bcl-2. Moreover, WIN-induced apoptosis is associated with JNK/p38 MAPK pathway activation and mitochondrial depolarisation demonstrated by a cytofluorimetric assay. The results also show that in HepG2 cells WIN markedly increases the level of the transcription factor PPARgamma in a dose- and time-dependent manner. The addition of the PPARgamma antagonists GW9662 and T0070907 significantly reduces the effects of the drug on both cell viability and the levels of survivin, phospho-AKT and phospho-BAD, suggesting that PPARgamma plays a key role in WIN-induced apoptosis. Altogether, the results seem to indicate a potential therapeutic role of WIN in hepatic cancer treatment.

Cannabinoid-associated cell death mechanisms in tumor models (review).

In recent years, cannabinoids (the active components of Cannabis sativa) and their derivatives have received considerable interest due to findings that they can affect the viability and invasiveness of a variety of different cancer cells. Moreover, in addition to their inhibitory effects on tumor growth and migration, angiogenesis and metastasis, the ability of these compounds to induce different pathways of cell death has been highlighted. Here, we review the most recent results generating interest in the field of death mechanisms induced by cannabinoids in cancer cells. In particular, we analyze the pathways triggered by cannabinoids to induce apoptosis or autophagy and investigate the interplay between the two processes. Overall, the results reported here suggest that the exploration of molecular mechanisms induced by cannabinoids in cancer cells can contribute to the development of safe and effective treatments in cancer therapy.

Notch inhibition restores TRAIL-mediated apoptosis via AP1-dependent upregulation of DR4 and DR5 TRAIL receptors in MDA-MB-231 breast cancer cells

Notch is a family of transmembrane receptors whose activation through proteolytic cleavage by γ-secretase targets genes which participate in cell development, differentiation and tumorigenesis. Notch signaling is constitutively activated in various cancers, including breast cancer and its upregulation is usually related with poor clinical outcomes. Therefore, targeting Notch signaling with γ-secretase inhibitors (GSIs) is considered a promising strategy for cancer treatment. We report that the γ-secretase inhibitor-I (GSI-I) sensitizes human breast cancer cells to apoptosis mediated by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). The antiproliferative GSI-I/TRAIL synergism was stronger in ER-negative MDA-MB-231 breast cancer cells compared with ER-positive MCF-7 cells. In MDA-MB-231 cells, GSI-I treatment induced upregulation of DR4 and DR5 TRAIL receptors. This effect seemed to be related to the activation of the transcription factor AP1 that was a consequence of Notch inhibition, as demonstrated by Notch-1 silencing experiments. Combined treatment induced loss of the mitochondrial transmembrane potential and activation of caspases. GSI-I alone and/or GSI-I/TRAIL combination also induced a significant decrease in the levels of some survival factors (survivin, c-IAP-2, Bcl-xL, BimEL and pAKT) and upregulation of pro-apoptotic factors BimL, BimS and Noxa, enhancing the cytotoxic potential of the two drugs. Taken together, these results indicate for the first time that GSI-I/TRAIL combination could represent a novel and potentially effective tool for breast cancer treatment.

Diorganotin(IV) N-acetyl-L-cysteinate complexes: Synthesis, solid state, solution phase, DFT and biological investigations

Diorganotin(IV) complexes of N-acetyl-L-cysteine (H(2)NAC; (R)-2-acetamido-3-sulfanylpropanoic acid) have been synthesized and their solid and solution-phase structural configurations investigated by FTIR, Mössbauer, (1)H, (13)C and (119)Sn NMR spectroscopy. FTIR results suggested that in R(2)Sn(IV)NAC (R = Me, Bu, Ph) complexes NAC(2-) behaves as dianionic tridentate ligand coordinating the tin(IV) atom, through ester-type carboxylate, acetate carbonyl oxygen atom and the deprotonated thiolate group. From (119)Sn Mössbauer spectroscopy it could be inferred that the tin atom is pentacoordinated, with equatorial R(2)Sn(IV) trigonal bipyramidal configuration. In DMSO-d(6) solution, NMR spectroscopic data showed the coordination of one solvent molecule to tin atom, while the coordination mode of the ligand through the ester-type carboxylate and the deprotonated thiolate group was retained in solution. DFT (Density Functional Theory) study confirmed the proposed structures in solution phase as well as the determination of the most probable stable ring conformation. Biological investigations showed that Bu(2)SnCl(2) and NAC2 induce loss of viability in HCC cells and only moderate effects in non-tumor Chang liver cells. NAC2 showed lower cytotoxic activity than Bu(2)SnCl(2), suggesting that the binding with NAC(2-) modulates the marked cytotoxic activity exerted by Bu(2)SnCl(2). Therefore, these novel butyl derivatives could represent a new class of anticancer drugs.

Synthesis, chemical characterization and biological activity of new histone acetylation/deacetylation specific inhibitors: A novel and potential approach to cancer therapy

Three new triorganotin(IV) complexes of valproic acid (vp1, Me3Sn-valproate; vp2, Bu3Sn-valproate; vp3, Ph3Sn-valproate) have been synthesized and investigated by spectroscopic and biological methods. An anionic, monodentate valproate ligand was observed, ester-like coordinating the tin atom on a tetra-coordinated, monomeric environment. The structures, though, can distort towards a penta-coordination, as a consequence of a long range O···Sn interaction. Crystallographic and NMR findings confirm this situation both in solid state and solution. Biological finding evidenced a clear cytotoxic action of the complexes in hepatocellular carcinoma cell cultures: one of the complexes induced an 80% cell viability reduction after 24h treatment in HepG2 cells. This effect was accompanied by the appearance of biochemical signs of apoptosis. In Chang liver cells, the same compound induced only modest effects, suggesting a potential use as anti-cancer drug. Preliminary evaluations on hyperacetylation state of histone H3 in tributyltin-valproate treated HepG2 cells showed an increase in Ac-H3 (histone H3 acetylated at lys-9 and lys-14), suggesting that the compound maintains the deacetylation inhibition activity of its ligand valproate.