Mutant p53 reactivator SLMP53-2 hinders ultraviolet B radiation-induced skin carcinogenesis.

The growing incidence of skin cancer (SC) has prompted the search for additional preventive strategies to counteract this global health concern. Mutant p53 (mutp53), particularly with ultraviolet radiation (UVR) signature, has emerged as a promising target for SC prevention based on its key role in skin carcinogenesis. Herein, the preventive activity of our previously disclosed mutp53 reactivator SLMP53-2 against UVR-induced SC was investigated. The pre-treatment of keratinocyte HaCaT cells with SLMP53-2, before UVB exposure, depleted mutp53 protein levels with restoration of wild-type-like p53 DNA-binding ability and subsequent transcriptional activity. SLMP53-2 increased cell survival by promoting G1-phase cell cycle arrest, while reducing UVB-induced apoptosis through inhibition of c-Jun N-terminal kinase (JNK) activity. SLMP53-2 also protected cells from reactive oxygen species and oxidative damage induced by UVB. Moreover, it enhanced DNA repair through upregulation of nucleotide excision repair pathway and depletion of UVB-induced DNA damage, as evidenced by a reduction of DNA in comet tails, γH2AX staining and cyclobutane pyrimidine dimers (CPD) levels. SLMP53-2 further suppressed UVB-induced inflammation by inhibiting the nuclear translocation and DNA-binding ability of NF-κB, and promoted the expression of key players involved in keratinocytes differentiation. Consistently, the topical application of SLMP53-2 in mice skin, prior to UVB irradiation, reduced cell death and DNA damage. It also decreased the expression of inflammatory-related proteins and promoted cell differentiation, in UVB-exposed mice skin. Notably, SLMP53-2 did not show signs of skin toxicity for cumulative topical use. Overall, these results support a promising protective activity of SLMP53-2 against UVB-induced SC.

Norhierridin B, a New Hierridin B-Based Hydroquinone with Improved Antiproliferative Activity.

Hierridin B (6), a methylated hydroquinone isolated from the marine picocyanobacterium Cyanobium sp. LEGE 06113, moderately inhibited the growth of colon adenocarcinoma HT-29 cells. Aiming to improve the potential antitumor activity of this natural product, the demethylated analogue, norhierridin B (10), as well as its structurally-related quinone (9), were synthesized and evaluated for their growth inhibitory effect on a panel of human tumor cell lines, including the triple-negative breast cancer (TNBC) cells MDA-MB-231, SKBR3, and MDA-MB-468. Norhierridin B (10) showed a potent growth inhibitory effect on all cancer cell lines. Moreover, the growth inhibitory effect of compound 10 on MDA-MB-231 cells was associated with cell cycle arrest and apoptosis. Norhierridin B (10) interfered with several p53 transcriptional targets, increasing p21, Bax, and MDM2, while decreasing Bcl-2 protein levels, which suggested the potential activation of a p53 pathway. Altogether, these results evidenced a great improvement of the antitumor activity of hydroquinone 10 when compared to 6 and its structurally-related quinone (9). Notably, hydroquinone 10 displayed a prominent growth inhibitory activity against TNBC cells, which are characterized by high therapeutic resistance.

SLMP53-2 Restores Wild-Type-Like Function to Mutant p53 through Hsp70: Promising Activity in Hepatocellular Carcinoma.

Half of human cancers harbor TP53 mutations that render p53 inactive as a tumor suppressor. In these cancers, reactivation of mutant p53 (mutp53) through restoration of wild-type-like function constitutes a valuable anticancer therapeutic strategy. In order to search for mutp53 reactivators, a small library of tryptophanol-derived oxazoloisoindolinones was synthesized and the potential of these compounds as mutp53 reactivators and anticancer agents was investigated in human tumor cells and xenograft mouse models. By analysis of their anti-proliferative effect on a panel of p53-null NCI-H1299 tumor cells ectopically expressing highly prevalent mutp53, the compound SLMP53-2 was selected based on its potential reactivation of multiple structural mutp53. In mutp53-Y220C-expressing hepatocellular carcinoma (HCC) cells, SLMP53-2-induced growth inhibition was mediated by cell cycle arrest, apoptosis, and endoplasmic reticulum stress response. In these cells, SLMP53-2 restored wild-type-like conformation and DNA-binding ability of mutp53-Y220C by enhancing its interaction with the heat shock protein 70 (Hsp70), leading to the reestablishment of p53 transcriptional activity. Additionally, SLMP53-2 displayed synergistic effect with sorafenib, the only approved therapy for advanced HCC. Notably, it exhibited potent antitumor activity in human HCC xenograft mouse models with a favorable toxicological profile. Collectively, SLMP53-2 is a new mutp53-targeting agent with promising antitumor activity, particularly against HCC.

1,2-Dihydroxyxanthone: Effect on A375-C5 Melanoma Cell Growth Associated with Interference with THP-1 Human Macrophage Activity.

Xanthones have been suggested as prospective candidates for cancer treatment. 1,2- dihydroxyxanthone (1,2-DHX) is known to interfere with the growth of several cancer cell lines. We investigated the effects of 1,2-DHX on the growth of the A375-C5 melanoma cell line and THP-1 human macrophage activity. 1,2-DHX showed a moderate growth inhibition of A375-C5 melanoma cells (concentration that causes a 50% inhibition of cell growth (GI50) = 55.0 ± 2.3 µM), but strongly interfered with THP-1 human macrophage activity. Supernatants from lipopolysaccharide (LPS)-stimulated THP-1 macrophage cultures exposed to 1,2-DHX significantly increased growth inhibition of A375-C5 cells, when compared to supernatants from untreated LPS-stimulated macrophages or to direct treatment with 1,2-DHX only. 1,2-DHX decreased THP-1 secretion of interleukin-1ß (IL-1ß) and interleukin-10 (IL-10), but stimulated tumor necrosis factor-α (TNF-α) and transforming growth factor-ß1 (TGF-ß1) production. This xanthone also inhibited nitric oxide (NO) production by RAW 264.7 murine macrophages, possibly through inhibition of inducible NO synthase production. In conclusion, these findings suggest a potential impact of 1,2-DHX in melanoma treatment, not only due to a direct effect on cancer cells but also by modulation of macrophage activity.

New Alkoxy Flavone Derivatives Targeting Caspases: Synthesis and Antitumor Activity Evaluation.

The antitumor activity of natural flavonoids has been exhaustively reported. Previously it has been demonstrated that prenylation of flavonoids allows the discovery of new compounds with improved antitumor activity through the activation of caspase-7 activity. The synthesis of twenty-five flavonoids (4⁻28) with one or more alkyl side chains was carried out. The synthetic approach was based on the reaction with alkyl halide in alkaline medium by microwave (MW) irradiation. The in vitro cell growth inhibitory activity of synthesized compounds was investigated in three human tumor cell lines. Among the tested compounds, derivatives 6, 7, 9, 11, 13, 15, 17, and 18 revealed potent growth inhibitory activity (GI50 < 10 µM), being the growth inhibitory effect of compound 13 related with a pronounced caspase-7 activation on MCF-7 breast cancer cells and yeasts expressing human caspase-7. A quantitative structure-activity relationship (QSAR) model predicted that hydrophilicity, pattern of ring substitution/shape, and presence of partial negative charged atoms were the descriptors implied in the growth inhibitory effect of synthesized compounds. Docking studies on procaspase-7 allowed predicting the binding of compound 13 to the allosteric site of procaspase-7.

Increased viability but decreased culturability of Mycobacterium avium subsp. paratuberculosis in macrophages from inflammatory bowel disease patients under Infliximab treatment.

Mycobacterium avium subsp. paratuberculosis (MAP) has long been implicated as a triggering agent in Crohn's disease (CD). In this study, we investigated the growth/persistence of both M. avium subsp. hominissuis (MAH) and MAP, in macrophages from healthy controls (HC), CD and ulcerative colitis patients. For viability assessment, both CFU counts and a pre16SrRNA RNA/DNA ratio assay (for MAP) were used. Phagolysosome fusion was evaluated by immunofluorescence, through analysis of LAMP-1 colocalization with MAP. IBD macrophages were more permissive to MAP survival than HC macrophages (a finding not evident with MAH), but did not support MAP active growth. The lower MAP CFU counts in macrophage cultures associated with Infliximab treatment were not due to increased killing, but possibly to elevation in the proportion of intracellular dormant non-culturable MAP forms, as MAP showed higher viability in those macrophages. Increased MAP viability was not related to lack of phagolysosome maturation. The predominant induction of MAP dormant forms by Infliximab treatment may explain the lack of MAP reactivation during anti-TNF therapy of CD but does not exclude the possibility of MAP recrudescence after termination of therapy.

Epstein-Barr virus in inflammatory bowel disease-correlation with different therapeutic regimens.

BACKGROUND: Inflammatory bowel disease (IBD) is associated with a higher prevalence of opportunistic infections. Epstein-Barr virus (EBV) is a ubiquitous virus related to several malignancies, namely lymphoma; its prevalence in patients with IBD and its relation with different therapeutic regimens are not well studied. METHODS: Patients followed in our IBD outpatient clinic were consecutively enrolled for participation in a prospective study, and healthy volunteers were recruited as controls. EBV DNA was measured at least 1 time in each patient. RESULTS: Three hundred and seventy-nine individuals were enrolled in the study (93 treated with 5-aminosalicylates, 91 with azathioprine, 70 with infliximab, 43 with combined treatment with infliximab and azathioprine, and 82 controls). More than 90% of the patients had previous EBV exposure. EBV DNA was found in 132 samples (35%); its prevalence was significantly higher in every group of patients with IBD, comparing to controls. Among patients with IBD, infliximab with or without azathioprine was related to higher prevalence of EBV comparing to azathioprine alone or 5-aminosalicylates (P < 0.05). Age above 60 years was related to EBV DNA positivity with a specificity of 92%. Concerning treated groups, ulcerative colitis was the only risk factor identified for high levels of EBV DNA (>1000 and 2500 copies per milliliter). No relationship was found between EBV and C-reactive protein. CONCLUSIONS: IBD is a risk factor for the presence of EBV DNA in blood, particularly in older patients and in those taking infliximab. C-reactive protein was not related to EBV DNA prevalence.

Synthesis of tetrahydronaphthalene lignan esters by intramolecular cyclization of ethyl p-azidophenyl-2-phenylalkanoates and evaluation of the growth inhibition of human tumor cell lines.

Intramolecular cyclization via nitrenium ion of 2-phenylpentanoic/2-phenylbutanoic acid esters with a terminal p-azidophenyl group gives direct access to tetrahydronaphthalene lignan esters. The p-azidophenyl-substituted butanoate led to an ethyl spirodienone carboxylate, while its homologue pentanoate gave ethyl 4-(4-aminophenyl)-1,2,3,4-tetrahydronaphthalene-1-carboxylate in good yield. In contrast, the m-azidophenyl-substituted esters suffered aromatic nucleophilic addition of trifluoromethanesulfonate. X-ray crystallography established unequivocally the end products structure, and density functional theory studies were performed to rationalize the cyclization outcome. Reaction intermediates and end products were evaluated for their capacity to inhibit in vitro growth of the cell lines MCF-7 (breast cancer), NCI-H460 (lung cancer), SF-268 (CNS cancer), and UACC-62 (melanoma). Growth inhibition of breast, lung, and CNS cancer cell lines was observed with the spirodienone carboxylate, the m-nitrophenylalkyl iodides, and p-phenyl-substituted elongated ethyl esters, namely, the p-nitrophenylpentanoate and p-aminophenylbutanoate, with the latter being also effective on the melanoma cell line.

Bromoalkoxyxanthones as promising antitumor agents: synthesis, crystal structure and effect on human tumor cell lines.

In a study involving the synthesis of bis-intercalators, a bisxanthone and a minor product, 1-(6-bromohexyloxy)-xanthone were obtained. Although no capacity to inhibit the growth of human tumor cell lines was observed for the bisxanthone, the bromoalkoxyxanthone revealed this biological activity. In light of these results bromoalkylation of 3,4-dihydroxyxanthone furnished two bromohexyloxyxanthones that were investigated for their effect on the in vitro growth of human tumor cell lines MCF-7 (ER+, breast), MDA-MB-231 (ER-, breast), NCI-H460 (non-small lung), and SF-268 (central nervous system). The X-ray structure of 1-(6-bromohexyloxy)-xanthone revealed that the xanthone skeleton remains essentially planar forming a dihedral angle of 61.3(2) degrees with the 6-bromohexyl side chain. These results revealed bromoalkoxyxanthones as interesting scaffolds to look for potential anticancer drugs.

Synthesis of new heteroaryl and heteroannulated indoles from dehydrophenylalanines: Antitumor evaluation.

A 3-(dibenzothien-4-yl)indole and a phenylbenzothienoindole or a 3-(dibenzofur-4-yl)indole and a phenylbenzofuroindole were prepared by a metal-assisted C-N intramolecular cyclization of the methyl esters of N-Boc-(E) or (Z)-beta-dibenzothien-4-yl or beta-dibenzofur-4-yl dehydrophenylalanines. The latter were obtained by Suzuki cross-coupling of the methyl esters of N-Boc-(E) or (Z)-beta-bromodehydrophenylalanines with dibenzothien-4-yl or dibenzofur-4-yl boronic acids, in high yields. The intramolecular cyclization from E or Z pure Suzuki-coupling products gave the corresponding heteroaryl and heteroannulated indoles, in different ratios, by either direct cyclization or cyclization after isomerisation. Three of the cyclized compounds, the two heteroarylindoles and the phenylbenzothienoindole, were evaluated for their capacity to inhibit the in vitro growth of three human tumor cell lines, MCF-7 (breast adenocarcinoma), NCI-H460 (non-small cell lung cancer), and SF-268 (CNS cancer). The methyl 3-(dibenzothien-4-yl)indole-2-carboxylate was the most potent compound with GI(50) values ranging from 11 to 17microM.

Dihydroxyxanthones prenylated derivatives: synthesis, structure elucidation, and growth inhibitory activity on human tumor cell lines with improvement of selectivity for MCF-7.

The synthesis, structure elucidation, and antitumor activity of 11 xanthones are reported, being the compounds 3, 4, 6-8, and 9 described for the first time. Xanthones 1 and 2 were used as building blocks to obtain the prenylated derivatives 3-8. Prenylation was carried out using prenyl bromide in alkaline medium. Dihydropyranoxanthones 9-11 were obtained from compounds 4 and 5 by an oxidative ring closure. The structure of the compounds was established by IR, UV, MS, and NMR ((1)H, (13)C, COSY, HSQC, and HMBC) techniques and for compounds 4, 6, and 11 the structure was confirmed by X-ray crystallographic analysis. The effect of the 11 xanthones on the in vitro growth of four human tumor cell lines, MCF-7 (breast adenocarcinoma), NCI-H460 (non-small cell lung cancer), SF-268 (central nervous system cancer), and UACC-62 (melanoma) is also described.