Recent Methodologies That Exploit C-C Single-Bond Cleavage of Strained Ring Systems by Transition Metal Complexes.

In this review, synthetic and mechanistic aspects of key methodologies that exploit C-C single-bond cleavage of strained ring systems are highlighted. The focus is on transition-metal-catalyzed processes that are triggered by C-C bond activation and ß-carbon elimination, with the review concentrating on developments from mid-2009 to mid-2016.

Three-Component Azidation of Styrene-Type Double Bonds: Light-Switchable Behavior of a Copper Photoredox Catalyst.

[Cu(dap)2]Cl effectively catalyzes azide addition from the Zhdankin reagent to styrene-type double bonds, and subsequent addition of a third component to the benzylic position. In the presence of light, a photoredox cycle is implicated with polar components such as methanol or bromide adding to a benzylic cation. In the absence of light, by contrast, double azidation takes place to give diazides. Therefore, regioselective double functionalization can be achieved in good to excellent yields, with a switch between light and dark controlling the degree of azidation.

Targeting a Novel KRAS Binding Site: Application of One-Component Stapling of Small (5-6-mer) Peptides.

RAS proteins are central in the proliferation of many types of cancer, but a general approach toward the identification of pan-mutant RAS inhibitors has remained unresolved. In this work, we describe the application of a binding pharmacophore identified from analysis of known RAS binding peptides to the design of novel peptides. Using a chemically divergent approach, we generated a library of small stapled peptides from which we identified compounds with weak binding activity. Exploration of structure-activity relationships (SARs) and optimization of these early compounds led to low-micromolar binders of KRAS that block nucleotide exchange.

Synchronization of cortisol circadian rhythm by the pineal hormone melatonin in untreatable metastatic solid tumor patients and its possible prognostic significance on tumor progression.

BACKGROUND: Cancer progression has been associated with neuroendocrine alterations involved in the control of the circadian rhythms, particularly those of cortisol. Moreover, the evidence of an altered cortisol rhythm may predict a poor prognosis in cancer patients. Finally, cancer progression has been proven to be associated with alterations in the pineal gland, which plays a fundamental role in the control of circadian biological rhythms. On this basis, a study was planned to evaluate the effects of a chronic treatment with the pineal hormone melatonin (MLT) in advanced cancer patients with altered cortisol circadian rhythm. PATIENTS AND METHODS: The study included 14 untreatable metastatic cancer patients showing alterations of cortisol rhythm. They were treated by MLT at 20 mg/day orally, in the evening, for 3 consecutive months. RESULTS: a normalization of cortisol rhythm was achieved in 4/14 (29%) patients. Moreover, stable disease (SD) was obtained in 6/14 (43%) patients under MLT therapy, whereas the other 8 patients had progressive disease (PD). Finally, the percentage of cortisol rhythm normalization achieved in patients with SD was significantly higher than that observed in patients with PD. CONCLUSION: These results show that MLT may normalize cortisol rhythm in advanced cancer patients and this effect appears to be associated with SD, thus confirming the negative prognostic significance of cortisol rhythm alterations in cancer.

Enantioselective Narasaka-Heck cyclizations: synthesis of tetrasubstituted nitrogen-bearing stereocenters.

The first examples of highly enantioselective Narasaka-Heck cyclizations are described. A SPINOL-derived P,N-ligand system enables Pd-catalyzed 5-exo cyclization of a range of oxime esters with sterically diverse trisubstituted alkenes to generate dihydropyrroles containing tetrasubstituted nitrogen-bearing stereocenters in 56 to 86% yield and 90 : 10 to 95 : 5 e.r. These processes are rare examples of reactions that proceed via enantioselective migratory insertion of alkenes into Pd-N bonds, and the first where trisubstituted alkenes are used to generate tetrasubstituted stereocenters with high enantioselectivity.

Benzylic C-H Azidation Using the Zhdankin Reagent and a Copper Photoredox Catalyst.

An azidation method for C-N bond formation at benzylic C-H positions is described using copper-catalyzed visible light photochemistry and the Zhdankin azidoiodinane reagent. The method is applicable to a wide range of substrates bearing different functional groups and having a primary, secondary, or tertiary benzylic position, and is thought to proceed through a radical chain reaction.

Oxyarylation and aminoarylation of styrenes using photoredox catalysis.

A three-component coupling of styrenes is reported, using photoredox catalysis to achieve simultaneous arylation and C-O or C-N bond formation across the styrene double bond.

Synthesis and biological evaluation of 1,4-diaryl-2-azetidinones as specific anticancer agents: activation of adenosine monophosphate activated protein kinase and induction of apoptosis.

A series of novel 1,4-diaryl-2-azetidinones were synthesized and evaluated for antiproliferative activity, cell cycle effects, and apoptosis induction. Strong cytotoxicity was observed with the best compounds (±)-trans-20, (±)-trans-21, and enantiomers (+)-trans-20 and (+)-trans-21, which exhibited IC(50) values of 3-13 nM against duodenal adenocarcinoma cells. They induced inhibition of tubulin polymerization and subsequent G2/M arrest. This effect was accompanied by activation of AMP-activated protein kinase (AMPK), activation of caspase-3, and induction of apoptosis. Additionally, the most potent compounds displayed antiproliferative activity against different colon cancer cell lines, opening the route to a new class of potential therapeutic agents against colon cancer.

Endocrine effects of erythropoietin in cancer patients.

The recent advances in the knowledge of the psychoneuroimmunological pathogenesis of human neoplasms have demonstrated the existence of feed-back mechanisms operating between interleukins and endocrine secretions, which play an important role in the regulation of the immune responses, including the anticancer immunity. In contrast, few studies only have been performed to investigate the possible relation between endocrine activities and hematopoietic growth factors. The present study was performed to analyze the acute endocrine effects of erythropoietin-alpha (EPO) on the main endocrine secretions. The study was carried out in 10 advanced solid tumor patients. EPO was injected subcutaneously at a dose of 10,000 U, and venous blood samples were collected before and 2, 4 and 6 h after EPO administration. No significant changes in mean serum levels of FSH, LH and TSH were seen in response to EPO. Cortisol and DHEAS concentrations increased after EPO injection, whereas those of PRL decreased, but none of these differences was statistically significant. Finally, mean serum levels of both growth hormone (GH) and somatomedin-C (IGF-1) significantly decreased after EPO administration. This preliminary study shows that EPO may inhibit GH secretion from the pituitary gland and IGF-1 production. Since GH would stimulate EPO release, the results of this study may suggest the existence of feedback mechanism operating between GH secretion and EPO production, with inhibitory effect of EPO on GH secretion, and stimulatory action of GH on EPO production. Therefore, this study would describe the first example of hemato-endocrine feedback mechanisms. Moreover, this study, by showing an inhibitory effect of EPO on IGF-1 secretion, would suggest a possible use of EPO in the medical oncology not only for the treatment of cancer related anemia, but also to counteract tumor growth by blocking IGF-1 production, which has been proven to be a growth factor for several tumor histotypes. Obviously, IGF-1 is not the only tumor growth factor, but it could play a fundamental role in the regulation of production and activity of several other tumor growth factors. In any case, this study describes the only acute endocrine effects of EPO. Therefore, further studies, by evaluating the endocrine effects of a chronic treatment with EPO, will be required to establish which may be its effect on IGF-1 endogenous production, and its consequence on survival time.