α4-α5 Helices on Surface of KRAS Can Accommodate Small Compounds That Increase KRAS Signaling While Inducing CRC Cell Death.

KRAS is the most frequently mutated oncogene associated with the genesis and progress of pancreatic, lung and colorectal (CRC) tumors. KRAS has always been considered as a therapeutic target in cancer but until now only two compounds that inhibit one specific KRAS mutation have been approved for clinical use. In this work, by molecular dynamics and a docking process, we describe a new compound (P14B) that stably binds to a druggable pocket near the α4-α5 helices of the allosteric domain of KRAS. This region had previously been identified as the binding site for calmodulin (CaM). Using surface plasmon resonance and pulldown analyses, we prove that P14B binds directly to oncogenic KRAS thus competing with CaM. Interestingly, P14B favors oncogenic KRAS interaction with BRAF and phosphorylated C-RAF, and increases downstream Ras signaling in CRC cells expressing oncogenic KRAS. The viability of these cells, but not that of the normal cells, is impaired by P14B treatment. These data support the significance of the α4-α5 helices region of KRAS in the regulation of oncogenic KRAS signaling, and demonstrate that drugs interacting with this site may destine CRC cells to death by increasing oncogenic KRAS downstream signaling.

Synthesis of Substituted Pyrazoles from Aryl-sydnones.

BACKGROUND: In this current work, a new synthesis strategy was developed to obtain 1,3,4-trisubstituted pyrazoles derivatives. METHODS: A series of 1,3,4-trisubstituted pyrazoles have been prepared via 1,3-dipolar cycloaddition reaction of 3-phenylsydnones with a variety of alkenes derivatives, symmetric and non-symmetric alkynes derivatives, N-phenyl-maleimide, N-benzylmaleimides, and maleic anhydride under conventional manner. RESULTS: Moreover, in this work, it has been demonstrated that the 4-bromopyrazole intermediates can be further functionalized by a combination of Suzuki-Miyaura crosscoupling reactions with aryl-boronic acids and N-arylation reactions of anilines. CONCLUSION: In summary, we have developed a new method to obtain 1,3,4 triarylated pyrazoles through 3-phenylsydnone 1,3-dipolar cycloadditions. By comparing the different reactions, it is apparent that high temperatures and xylene as solvent are key to achieving pyrazoles derivatives. The best yields were observed for symmetric and non-symmetric alkynes as dipolarophiles.

Multigram scale synthesis of polycyclic lactones and evaluation of antitumor and other biological properties.

An efficient four-step synthesis of tetracyclic lactones from 1,4-benzodioxine-2-carboxylic acid was developed. Ellipticine derivatives exhibit antitumor activity however only a few derivatives without carbazole subunit have been studied to date. Herein, several tetracyclic lactones were synthesized and biologically evaluated. Several compounds (2a, 3a, 4a and 5a) were found to be inhibitors of the Kras-Wnt pathway. The lactone 2a also exerted a potent inhibition of Tau protein translation and was shown to have capacity for CYP1A1-bioactivation. The results obtained are further evidence of the therapeutic potential of tetracyclic lactones related to ellipticine. Molecular modeling studies showed that compound 2a is inserted between helix α3 and α4 of the KRas protein making interactions with the hydrophobic residues Phe90, Glu91, Ile9364, Hie94, Leu133 and Tyr137and a hydrogen bond with residue Arg97.

Substituted tetrahydroisoquinolines: synthesis, characterization, antitumor activity and other biological properties.

This work deals with the molecular design, synthesis and biological activity of a series of tetrahydro[1,4]dioxanisoquinolines and dimethoxyisoquinoline analogues. This study describes the synthesis strategy of these potential antitumor compounds, their multi-step synthesis and their optimization. A series of tetrahydroisoquinolines was synthesized and their cytotoxicity evaluated. Some of these tetrahydroisoquinolines showed promising KRas inhibition, antiangiogenesis activity and antiosteoporosis properties. Molecular modeling studies showed that compound 12 bind in the p1 pocket of the KRas protein making interactions with the hydrophobic residues Leu56, Tyr64, Tyr71 and Thr74 and hydrogen bonds with residues Glu37 and Asp38.

Synthesis and structure-activity relationships of new benzodioxinic lactones as potential anticancer drugs.

A set of disubstituted tetracyclic lactones has been synthesized and tested for potential antitumor activity. Several of them possess a noticeable cytotoxicity against L1210 and HT-29 colon cells in vitro. Relationships between chain nature and biological properties were sought. Lactones with a pentyl or hexyl substituent at C-11 are the most active ones. The introduction of a functional group at the side chain of C-11 modified the potency; carboxylic acid and primary amine decreased the cytotoxicity, whereas a cyano group increased the activity. An extensive structure-activity relationship study of these derivatives, including carbon homologues and bioisosteres has been performed. The synthesis and cytotoxicity of these compounds are discussed. Two lactones are recognized as potential lead compounds.

Synthesis and biological evaluation of modified acridines: the effect of N- and O- substituent in the nitrogenated ring on antitumor activity.

A series of new acridines has been prepared by cyclodehydration of N-(2,3-dihydro-1,4-benzodioxin-6-yl)anthranilic acid in acidic media following classical procedures. All these compounds have in common a dioxygenated ring fused to the acridine. The tetracyclic system possesses a linear or angular structure formed by intramolecular cyclisation. The last ring and the substituent of the system modify, in an interesting way, the antitumor activity of acridines. Several of the studied compounds displayed significant cytotoxic activity (inhibition of L1210 and HT-29 cell proliferation). The most cytotoxic compound 13a, shows more activity than m-AMSA in inhibiting L1210 and HT-29 cell proliferation and this compound has been selected as a development candidate for further evaluation. The activity results also indicate that the new 11-O-substituted compounds are of considerable interest with high levels of cytotoxic activity. The angular or non-linear dioxinoacridine 10 was equiactive with the linear structure 7. Pentacyclic analogues (14 and 15) were more cytotoxic than the tetracyclic compounds (up to twofold).

Synthesis and biological activity of new class of dioxygenated anticancer agents.

This paper describes extensive research on the activity of more of 100 cytotoxic compounds containing an oxygenated ring in their structure and isolated from natural plants or prepared by semisynthesis or synthesis from available intermediates. Anticancer drugs have been classified according to the chemical structure of the natural products that are considered to lead the series. The origin and mechanism of action involved in each case have been considered. This new family of natural, semisynthetic and synthetic products includes compounds with interesting antitumor activity such as podophyllotoxin derivatives, NK-611 (15), TOP-53 (16), NPF (24) and Tafluposide (28); camptothecin analogs such as 45 with a considerable cytotoxicity against beta-cell chronic lymphocytic leukemia (CLL), and 52 (new piperazinyl-CPT analog). New dioxygenated ellipticine analogs showed more activity and stability than the natural pattern when the structure incorporated a lactone function instead of the pyridine ring. In the acridine series the new tetracyclic derivatives 75 and 76 containing ethylenedioxy groups at the 2- and 3-positions of the acridine system exhibited the same activity as m-AMSA in vivo against murine P-388 leukemia. Other isolated compounds containing a dioxygenated ring in their structure such as 100 and 101 showed antitumor activities related to kinase inhibition, and are attractive candidates for development of new synthetic antitumor agents.

Cyclin-dependent kinases 4 and 6 control tumor progression and direct glucose oxidation in the pentose cycle.

Cyclin-dependent kinases CDK4 and CDK6 are essential for the control of the cell cycle through the G(1) phase. Aberrant expression of CDK4 and CDK6 is a hallmark of cancer, which would suggest that CDK4 and CDK6 are attractive targets for cancer therapy. Herein, we report that calcein AM (the calcein acetoxymethyl-ester) is a potent specific inhibitor of CDK4 and CDK6 in HCT116 human colon adenocarcinoma cells, inhibiting retinoblastoma protein (pRb) phosphorylation and inducing cell cycle arrest in the G(1) phase. The metabolic effects of calcein AM on HCT116 cells were also evaluated and the flux between the oxidative and non-oxidative branches of the pentose phosphate pathway was significantly altered. To elucidate whether these metabolic changes were due to the inhibition of CDK4 and CDK6, we also characterized the metabolic profile of a CDK4, CDK6 and CDK2 triple knockout of mouse embryonic fibroblasts. The results show that the metabolic profile associated with the depletion of CDK4, CDK6 and CDK2 coincides with the metabolic changes induced by calcein AM on HCT116 cells, thus confirming that the inhibition of CDK4 and CDK6 disrupts the balance between the oxidative and non-oxidative branches of the pentose phosphate pathway. Taken together, these results indicate that low doses of calcein can halt cell division and kill tumor cells. Thus, selective inhibition of CDK4 and CDK6 may be of greater pharmacological interest, since inhibitors of these kinases affect both cell cycle progression and the robust metabolic profile of tumors.

Synthesis, anti-inflammatory activity, and in vitro antitumor effect of a novel class of cyclooxygenase inhibitors: 4-(aryloyl)phenyl methyl sulfones.

Following our previous research on anti-inflammatory drugs (NSAIDs), we report on the design and synthesis of 4-(aryloyl)phenyl methyl sulfones. These substances were characterized for their capacity to inhibit cyclooxygenase (COX-1 and COX-2) isoenzymes. Molecular modeling studies showed that the methylsulfone group of these compounds was inserted deep in the pocket of the human COX-2 binding site, in an orientation that precludes hydrogen bonding with Arg120, Ser353, and Tyr355 through their oxygen atoms. The N-arylindole 33 was the most potent inhibitor of COX-2 and also the most selective (COX-1/COX-2 IC(50) ratio was 262). The indole derivative 33 was further tested in vivo for its anti-inflammatory activity in rats. This compound showed greater inhibitory activity than ibuprofen. Other compounds (20, 26, 9, and 30) showed strong activity against carrageenan-induced inflammation. The latter compounds showed a weak capacity to inhibit the proliferation of human cell lines K562, NCI-H460, and HT-29 in vitro.