Benzodeazaoxaflavins as Sirtuin Inhibitors with Antiproliferative Properties in Cancer Stem Cells

Inhibition of sirtuins has recently been proposed as a promising anticancer strategy. Some of the new benzodeazaoxaflavins (<b>2a</b>, <b>2b</b>, and <b>2d</b>) here reported as SIRT1/2 inhibitors were endowed with pro-apoptotic properties in human U937 leukemia cells and, most importantly, together with the prototype MC2141 (<b>1</b>) displayed antiproliferative effects in cancer stem cells from patients with colorectal carcinoma and glioblastoma multiforme, known to be highly tumorigenic, resistant to conventional cancer chemotherapy, and responsible, at least in part, for cancer relapse or recurrence

2-(Alkyl/Aryl)Amino-6-Benzylpyrimidin-4(3<i>H</i>)-ones as Inhibitors of Wild-Type and Mutant HIV-1: Enantioselectivity Studies

The single enantiomers of two pyrimidine-based HIV-1 non-nucleoside reverse transcriptase inhibitors, <b>1</b> (MC1501) and <b>2</b> (MC2082), were tested in both cellular and enzyme assays. In general, the <i>R</i> forms were more potent than their <i>S</i> counterparts and racemates and (<i>R</i>)-<b>2</b> was more efficient than (<i>R</i>)-<b>1</b> and the reference compounds, with some exceptions. Interestingly, (<i>R</i>)-<b>2</b> displayed a faster binding to K103N RT with respect to WT RT, while (<i>R</i>)-<b>1</b> showed the opposite behavior

Inhibition values of 4, 10, 13 and 14 against the catalytic domain of hDNMT3A, hDNMT1 and G9a.

<p>^*Values are means of at least three experiments. ^†Compounds were tested in a 10-dose IC₅₀ mode with 2-fold serial dilution starting at 400 µM. For <b>4</b>, <b>13</b> and <b>14</b> it was no possible to determine IC₅₀ values (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0096941#pone.0096941.s001" target="_blank">File S1</a>).</p

Effect of selected compounds on the induction of the luciferase signal at the CMV-luc construct in KG-1 cells.

<p>(A) CMV-luc construct to detect changes in methylation at the CMV promoter in KG-1 cells. (B) Modulation of induction of luciferase expression of CMV-luc after treatment with different doses of <b>1</b>, <b>4</b>, <b>10</b>, <b>13</b> and <b>14</b>. SGI-1027 was used as a reference drug. Values are means of at least two experiments. Cytotoxicity of DNMT inhibitors in KG-1 cells causes a decrease or loss of luciferase induction.</p

Effects of selected compounds in human lymphoma U-937 and RAJI cells.

<p>Cells were treated with the indicated concentration of compounds <b>4</b>, <b>10</b>, <b>13</b> and <b>14</b> for up to 72 h. Antiproliferative effects (left) and cell death induction (right) on (A) U-937 and (B) RAJI lymphoma cell lines. Results are the mean ± SD of at least three independent experiments. *, **, *** indicate p<0.05, p<0.01, p<0.005 versus untreated cells, respectively.</p

Docking studies of 4 and 14 into the DNMT3A active site.

<p>Experimental (A) and theoretical (B and C) binding mode of AdoHcy (A), <b>4</b> (B) and <b>14</b> (C) in the DNMT3A active site. Protein is depicted as light yellow ribbons and sticks while ligands are depicted as red sticks. Hydrogen-bonds are depicted as dashed blue lines.</p

Percent of inhibition of <b>4–18</b> against hDNMT1 and hDNMT3A.

<p>Values are means of two to five experiments ± standard deviation.</p>†<p>ND, not determined.</p><p>*Percent of inhibition at 32 and 10 µM: 18±0.8 and 6.5±0.7%, respectively.</p

Effect of selected quinazoline analogues <b>4</b>, <b>10</b>, <b>13</b> and <b>14</b> on human lymphoma U-937 and RAJI cell viability at 48 h^*.

<p>*Data represent the mean (± SD) of at least three independent experiments.</p

Quinazoline-based modulators of epigenetic targets.

<p>(A) Known quinazolines (<b>1–3</b>) as G9a/GLP inhibitors. (B) Novel 6,7-desmethoxyquinazolines <b>4–18</b>. (C) Synthetic scheme for the preparation of <b>4–18</b>.</p

Discovery of Salermide-Related Sirtuin Inhibitors: Binding Mode Studies and Antiproliferative Effects in Cancer Cells Including Cancer Stem Cells

Chemical changes performed on <b>1a</b> (sirtinol) led to a series of SIRT1/2 inhibitors, in some cases more potent than <b>1a</b> mainly against SIRT1. Tested in human leukemia U937 cells, the benzamide and anilide derivatives <b>1b</b>, <b>1c</b>, <b>2b</b>, and <b>2c</b> as well as the 4-(2-phenylpropyl)­thioanalogue <b>4c</b> showed huge apoptosis induction, while some sulfinyl and sulfonyl derivatives (<b>5b</b>, <b>5c</b>, and <b>6a</b>–<b>c</b>) were highly efficient in granulocytic differentiation. When assayed in human leukemia MOLT4 as well as in human breast MDA-MB-231 and colon RKO cancer cell lines, the anilide <b>2b</b> (salermide) and the phenylpropylthio analogue <b>4b</b> emerged as the most potent antiproliferative agents. Tested on colorectal carcinoma and glioblastoma multiforme cancer stem cells (CSCs) from patients, <b>2b</b> was particularly potent against colorectal carcinoma CSCs, while <b>4b</b>, <b>6a</b>, and the SIRT2-selective inhibitor AGK-2 showed the highest effect against glioblastoma multiforme CSCs. Such compounds will be further explored for their broad-spectrum anticancer properties