Delphine Lamoral-Theys

Lycorine, the main phenanthridine Amaryllidaceae alkaloid, exhibits significant antitumor activity in cancer cells that display resistance to proapoptotic stimuli: an investigation of structure-activity relationship and mechanistic insight.

Twenty-two lycorine-related compounds were investigated for in vitro antitumor activity using four cancer cell lines displaying different levels of resistance to proapoptotic stimuli and two cancer cell lines sensitive to proapoptotic stimuli. Lycorine and six of its congeners exhibited potency in the single-digit micromolar range, while no compound appeared more active than lycorine. Lycorine also displayed the highest potential (in vitro) therapeutic ratio, being at least 15 times more active against cancer than normal cells. Our studies also showed that lycorine exerts its in vitro antitumor activity through cytostatic rather than cytotoxic effects. Furthermore, lycorine provided significant therapeutic benefit in mice bearing brain grafts of the B16F10 melanoma model at nontoxic doses. Thus, the results of the current study make lycorine an excellent lead for the generation of compounds able to combat cancers, which are naturally resistant to proapoptotic stimuli, such as glioblastoma, melanoma, non-small-cell-lung cancers, and metastatic cancers, among others.

Amaryllidaceae alkaloids belonging to different structural subgroups display activity against apoptosis-resistant cancer cells.

Fifteen Amaryllidaceae alkaloids (1-15) were evaluated for their antiproliferative activities against six distinct cancer cell lines. Several of these natural products were found to have low micromolar antiproliferative potencies. The log P values of these compounds did not influence their observed activity. When active, the compounds displayed cytostatic, not cytotoxic activity, with the exception of pseudolycorine (3), which exhibited cytotoxic profiles. The active compounds showed similar efficacies toward cancer cells irrespective of whether the cell lines were responsive or resistant to proapoptotic stimuli. Altogether, the data from the present study revealed that lycorine (1), amarbellisine (6), haemanthamine (14), and haemanthidine (15) are potentially useful chemical scaffolds to generate further compounds to combat cancers associated with poor prognoses, especially those naturally resistant to apoptosis, such as glioblastoma, melanoma, non-small-cell lung, and metastatic cancers.

Lycorine and its derivatives for anticancer drug design.

Amaryllidaceae alkaloids are extensively studied for their biological activities in several pharmaceutical areas, including, for example, Alzheimers disease for which galanthamine has already reached the market. Among this chemical family, lycorine displays very promising anti-tumor properties. This review first focuses on the chemical diversity of natural and synthetic analogues of lycorine and their metabolites, and then on mechanisms of action and biological targets through which lycorine and its derivatives display their anti-tumor activity. Our analysis of the structure-activity relationships of this family of compounds highlights the existence of various potential leads for the development of novel anticancer agents.

FTIR spectroscopy: A new valuable tool to classify the effects of polyphenolic compounds on cancer cells

Polyphenolic compounds are an important part of human diet and regular consumption of fruits, vegetables and tea is associated with reduced risk of cancer. Dietary polyphenols display a vast array of cellular effects but the large number of data published in the literature makes it difficult to determine the main mechanisms of action associated and to identify molecules with original mechanisms. Therefore, there is an increasing demand for more systemic approaches in order to obtain a global insight of the biochemical processes mediated by polyphenols. Here, we used Fourier transform infrared (FTIR) spectroscopy to analyze cancer cells exposed in vitro to 6 polyphenols: 3 natural well documented polyphenols (curcumin, epigallocatechin gallate (EGCG) and quercetin) and 3 synthetic molecules with a very closely related chemical structure. Statistical analyses on FTIR spectra allowed the comparison of global effects of the 6 compounds and evidenced some common or different features in the cell perturbations among natural and synthetic molecules. Interestingly, marked metabolic changes induced by polyphenols closely related from a chemical point of view were identified. Furthermore, many metabolic changes could be detected as early as after 2h incubation with the drugs.

In search of a cytostatic agent derived from the alkaloid lycorine: Synthesis and growth inhibitory properties of lycorine derivatives

As a continuation of our studies aimed at the development of a new cytostatic agent derived from an Amaryllidaceae alkaloid lycorine, we synthesized 32 analogues of this natural product. This set of synthetic analogues included compounds incorporating selective derivatization of the C1 versus C2 hydroxyl groups, aromatized ring C, lactamized N6 nitrogen, dihydroxylated C3-C3a olefin functionality, transposed olefin from C3-C3a to C2-C3 or C3a-C4, and C1 long-chain fatty esters. All synthesized compounds were evaluated for antiproliferative activities in vitro in a panel of tumor cell lines including those exhibiting resistance to proapoptotic stimuli and representing solid cancers associated with dismal prognoses, such as melanoma, glioblastoma, and non-small-cell lung cancer. Most active analogues were not discriminatory between cancer cells displaying resistance or sensitivity to apoptosis, indicating that these compounds are thus able to overcome the intrinsic resistance of cancer cells to pro-apoptotic stimuli. 1,2-Di-O-allyllycorine was identified as a lycorine analogue, which is 100 times more potent against a U373 human glioblastoma model than the parent natural product. Furthermore, a number of synthetic analogues were identified as promising for the forthcoming in vivo studies.

DYRK1A Kinase Inhibitors with Emphasis on Cancer

Various types of cancers (including gliomas, melanomas, and esophageal, pancreas and non-small-cell lung cancers) display intrinsic resistance to pro-apoptotic stimuli, such as conventional chemotherapy and radiotherapy, and/or the activation of a multidrug resistance phenotype, which are major barriers to effective treatment and lead to poor patient prognosis. The DYRK1A kinase is directly implicated in the resistance of cancer cells to pro-apoptotic stimuli and drives several pathways that enhance proliferation, migration, and the reduction of cell death, leading to very aggressive biological behavior in cancer cell populations. The DYRK1A kinase is also implicated in neurological diseases and in neoangiogenic processes. Thus, the DYRK1A kinase is of great interest for both cancer and neuroscience research. During the last decade, numerous compounds that inhibit DYRK1A have been synthesized. The present review discusses the available molecules known to interfere with DYRK1A activity and the implications of DYRK1A in cancer and other diseases and serves as a rational analysis for researchers who aim to improve the anti-DYRK1A activity of currently available compounds.

Simple di- and trivanillates exhibit cytostatic properties toward cancer cells resistant to pro-apoptotic stimuli

A series of 33 novel divanillates and trivanillates were synthesized and found to possess promising cytostatic rather than cytotoxic properties. Several compounds under study decreased by >50% the activity of Aurora A, B, and C, and WEE1 kinase activity at concentrations <10% of their IC(50) growth inhibitory ones, accounting, at least partly, for their cytostatic effects in cancer cells and to a lesser extent in normal cells. Compounds 6b and 13c represent interesting starting points for the development of cytostatic agents to combat cancers, which are naturally resistant to pro-apoptotic stimuli, including metastatic malignancies.

Investigations of fungal secondary metabolites with potential anticancer activity.

Fourteen metabolites, isolated from phytopathogenic and toxigenic fungi, were evaluated for their in vitro antigrowth activity for six distinct cancer cell lines, using the MTT colorimetric assay. Bislongiquinolide (1) and dihydrotrichodimerol (5), which belong to the bisorbicillinoid structural class, displayed significant growth inhibitory activity against the six cancer cell lines studied, while the remaining compounds displayed weak or no activity. The data show that 1 and 5 have similar growth inhibitory activities with respect to those cancer cell lines that display certain levels of resistance to pro-apoptotic stimuli or those that are sensitive to apoptosis. Quantitative videomicroscopy analysis revealed that 1 and 5 exert their antiproliferative effect through cytostatic and not cytotoxic activity. The preliminary results from the current study have stimulated further structure-activity investigations with respect to the growth inhibitory activity of compounds belonging to the bisorbicillinoid group.

Structure–activity relationships and mechanism of action of antitumor bis 8-hydroxyquinoline substituted benzylamines

A series of twenty six 8-hydroxyquinoline substituted amines, structurally related to compounds 2 and 3, were synthesized to evaluate the effects of structural changes on antitumor activity and understand their mechanism of action. The studies were performed on a wide variety of cancer cell lines within glioma and carcinoma models. The results obtained from chemical models and biological techniques such as microarrays suggest the following hypothesis that a quinone methide intermediate which does not react with DNA but which gives covalent protein thiol adducts. Micro-array analysis showed that the drugs induce the expression of a variety of stress related genes responsible for the cytotoxic and cytostatic effects in carcinoma and glioblastoma cells respectively. The described analogues could represent new promising anti-cancer candidates with specific action mechanisms, targeting accessible thiols from specific proteins and inducing potent anti-cancer effects.

Evaluation of the antiproliferative activity of diterpene isonitriles from the sponge Pseudoaxinella flava in apoptosis-sensitive and apoptosis-resistant cancer cell lines.

One new (1) and three known (2-4) isonitrile diterpenes, isolated from the Caribbean sponge Pseudoaxinella flava, were assayed in human cancer cell lines in vitro using an MTT colorimetric assay and quantitative videomicroscopy. Compounds 1-4 displayed activity for human PC3 prostate apoptosis-sensitive cancer cell lines. Compounds 3 and 4 demonstrated similar growth inhibitory effects for three apoptosis-sensitive and three apoptosis-resistant cancer cell lines. Quantitative videomicroscopy analysis revealed that compounds 1 and 2 exerted their activity through cytotoxic effects, and compounds 3 and 4 through cytostatic effects. These results identify marine diterpene isonitriles as potential lead compounds for anticancer drug discovery.