Antonella Pepe

Transport and cytotoxicity of paclitaxel, docetaxel, and novel taxanes in human breast cancer cells

The resistance of tumors to classic taxanes (paclitaxel and docetaxel) presents problems in chemotherapy. Thus, new taxanes with higher antitumor activity in resistant tumors are synthesized. This study compared cytotoxicity and transport of paclitaxel and docetaxel with novel taxanes SB-T-1103, SB-T-1214, and SB-T-1216 in adriamycin-sensitive (MDA-MB-435) and -resistant (NCI/ADR-RES) human breast cancer cells. The cell lines examined differ in adriamycin transport, suggesting different expression of ABC membrane transporters. Reverse transcription-polymerase chain reaction revealed that NCI/ADR-RES cells expressed high levels of P-glycoprotein mRNA, which was absent in MDA-MB-435 cells, while the opposite was true for MRP2 mRNA. Both cell lines shared or differently expressed eight other ABC transporters and LRP. NCI/ADR-RES cells were 1,000-fold more resistant to paclitaxel and 600-fold more resistant to docetaxel in MTT assay than MDA-MB-435 cells, but almost equally sensitive to SB-T-1103, SB-T-1214, and SB-T-1216. This complied with the fact that NCI/ADR-RES cells absorbed almost 20-fold less [14C]paclitaxel, about 7-fold less docetaxel, and almost equal amounts of SB-T-1103, SB-T-1214, and SB-T-1216 as the MDA-MB-435 cells. Verapamil increased uptake of [14C]paclitaxel by NCI/ADR-RES cells 7-fold and decreased its efflux 2.5-fold; in contrast, it weakly influenced uptake and increased the efflux in MDA-MB-435 cells. SB-T-1103 and SB-T-1216 did not influence transport of paclitaxel, but SB-T-1214 decreased [14C]paclitaxel uptake in both cell lines indicating inhibition of uptake. This suggests that the novel taxanes are not inhibitors of P-glycoprotein. However, novel taxanes exert much higher activity on resistant tumor cells than classic taxanes and seem to be potential drugs for therapy in taxane-resistant tumors.

Novel C-seco-taxoids possessing high potency against paclitaxel-resistant cancer cell lines overexpressing class III β-tubulin

Novel C-seco-taxoids were synthesized from 10-deacetylbaccatin III and their potencies evaluated against drug-sensitive and drug-resistant cancer cell lines. The drug-resistant cell lines include ovarian cancer cell lines resistant to cisplatin, topotecan, adriamycin and paclitaxel overexpressing class III beta-tubulin, A2780TC1 and A2780TC3. The last two cell lines were selected through chronic exposure of A2780wt to paclitaxel and Pgp blocker cyclosporine. All novel C-seco-taxoids exhibited remarkable potency against A2780TC1 and A2780TC3 cell lines, and no cross resistance to cisplatin- and topotecan-resistant cell lines, A2780CIS and A2780TOP. Four of those C-seco-taxoids exhibit much higher activities than IDN5390 against paclitaxel-resistant cell lines, A2780ADR, A2780TC1 and A2780TC3. SB-CST-10202 possesses the best all-round high potencies across different drug-resistant cell lines. Molecular modeling studies, including molecular dynamics simulations, on the drug-protein complexes of class I and III beta-tubulins were performed to identify possible cause of the remarkable potency of these C-seco-taxoids against paclitaxel-resistant cell lines overexpressing class III beta-tubulin.

Mechanism of the Antiproliferative Activity of Some Naphthalene Diimide G-Quadruplex Ligands

G-quadruplexes are higher-order nucleic acid structures that can form in G-rich telomeres and promoter regions of oncogenes. Telomeric quadruplex stabilization by small molecules can lead to telomere uncapping, followed by DNA damage response and senescence, as well as chromosomal fusions leading to deregulation of mitosis, followed by apoptosis and downregulation of oncogene expression. We report here on investigations into the mechanism of action of tetra-substituted naphthalene diimide ligands on the basis of cell biologic data together with a National Cancer Institute COMPARE study. We conclude that four principal mechanisms of action are implicated for these compounds: 1) telomere uncapping with subsequent DNA damage response and senescence; 2) inhibition of transcription/translation of oncogenes; 3) genomic instability through telomeric DNA end fusions, resulting in mitotic catastrophe and apoptosis; and 4) induction of chromosomal instability by telomere aggregate formation.

Synthesis of fused bicyclic systems with nitrogen atom at the bridgehead, including indolizidines and quinolizidines.

Monocyclic as well as fused bicyclic systems with a nitrogen 10 atom at the bridgehead, including indolizidines and quinolizidines, can be prepared in four steps from N-Boc β-lactams. These easily prepared, highly robust, and flexible building blocks allow the incorporation of chirality and structural diversity, rendering the method feasible for diversity- as well as target-oriented synthesis.

Anticancer activity of 4-aminoquinoline-triazine based molecular hybrids

In this study the potential for anticancer activity of 4-aminoquinoline-triazine based hybrids has been investigated on 60 human cancer cell lines (NCI 60). The representative compounds show activity on a range of cell lines and apoptosis as the mode of growth inhibition.

Identification of the first inhibitor of the GBP1:PIM1 interaction. Implications for the development of a new class of anticancer agents against paclitaxel resistant cancer cells.

Class III β-tubulin plays a prominent role in the development of drug resistance to paclitaxel by allowing the incorporation of the GBP1 GTPase into microtubules. Once in the cytoskeleton, GBP1 binds to prosurvival kinases such as PIM1 and initiates a signaling pathway that induces resistance to paclitaxel. Therefore, the inhibition of the GBP1:PIM1 interaction could potentially revert resistance to paclitaxel. A panel of 44 4-azapodophyllotoxin derivatives was screened in the NCI-60 cell panel. The result is that 31 are active and the comparative analysis demonstrated specific activity in paclitaxel-resistant cells. Using surface plasmon resonance, we were able to prove that NSC756093 is a potent in vitro inhibitor of the GBP1:PIM1 interaction and that this property is maintained in vivo in ovarian cancer cells resistant to paclitaxel. Through bioinformatics, molecular modeling, and mutagenesis studies, we identified the putative NSC756093 binding site at the interface between the helical and the LG domain of GBP1. According to our results by binding to this site, the NSC756093 compound is able to stabilize a conformation of GBP1 not suitable for binding to PIM1.

Synthesis and structure-activity relationship studies of novel dihydropyridones as androgen receptor modulators.

A library of 3-hydroxy-2,3-dihydropyridones was synthesized, and their activities as antiandrogens were tested in the human prostate cancer cell line LNCaP. Structure-activity relationship (SAR) studies resulted in the identification of a potent compound whose activity is comparable to that of MDV3100. Homology modeling and molecular mechanics were used to build a structural model of the androgen receptor-ligand binding domain and to investigate the structural basis of the antagonism. The model is qualitatively consistent with the observed SAR. Moreover, the enrichment plot shows that screening with the model performs significantly better than random screening. Therefore, the model probably represents a realistic conformation of the antagonist form and can be utilized for structure-based design of novel antiandrogens.

Elucidating new structural features of the triazole scaffold for the development of mPGES-1 inhibitors

We report a new potent revisited version of a triazole-based inhibitor obtained by structure-based drug design on the human mPGES-1 crystal structure. Moreover, we disclosed the substitution with a halogen atom at position 5 as a new key factor influencing the biological activity on the mPGES-1 enzyme.

1′-Azido- and 1′-amino-1,3-dioxolan-4-ones

Abstract 1,3-Dioxolanone alcohols, prepared via the addition of chiral lithium enolates of 1,3-dioxolan-4-ones to aldehydes, are suitable intermediates for the synthesis of chiral trisubstituted isoserines or trisubstituted 3-hydroxy-β-lactams. In particular, the methyl ester of 2-methyl-3-(2-furyl)isoserinic acid and two 3-methyl-3-hydroxy-β-lactams bearing either a 2-furyl or a phenyl substituent at C-(4) have been prepared. The (2 R ,3 S ) stereochemistry of the isoserine, and the (3 R ,4 S ) stereochemistry of the two β-lactams is that required for the synthesis of taxoid analogues having the side-chain with the proper (2′ R ,3′ S ) configuration.

1,4-Substituted Triazoles as Nonsteroidal Anti-Androgens for Prostate Cancer Treatment

Prostate cancer (PC) is the fifth leading cause of cancer death in men, and the androgen receptor (AR) represents the primary target for PC treatment, even though the disease frequently progresses toward androgen-independent forms. Most of the commercially available nonsteroidal antiandrogens show a common scaffold consisting of two aromatic rings connected by a linear or a cyclic spacer. By taking advantage of a facile, one-pot click chemistry reaction, we report herein the preparation of a small library of novel 1,4-substituted triazoles with AR antagonistic activity. Biological and theoretical evaluation demonstrated that the introduction of the triazole core in the scaffold of nonsteroidal antiandrogens allowed the development of small molecules with improved overall AR-antagonist activity. In fact, compound 14d displayed promising in vitro antitumor activity toward three different prostate cancer cell lines and was able to induce 60% tumor growth inhibition of the CW22Rv1 in vivo xenograft model. These results represent a step toward the development of novel and improved AR antagonists.