Inhibition of Wnt signalling and breast tumour growth by the multi-purpose drug suramin through suppression of heterotrimeric G proteins and Wnt endocytosis.

Overactivation of the Wnt signalling pathway underlies oncogenic transformation and proliferation in many cancers, including the triple-negative breast cancer (TNBC), the deadliest form of tumour in the breast, taking about a quarter of a million lives annually worldwide. No clinically approved targeted therapies attacking Wnt signalling currently exist. Repositioning of approved drugs is a promising approach in drug discovery. In the present study we show that a multi-purpose drug suramin inhibits Wnt signalling and proliferation of TNBC cells in vitro and in mouse models, inhibiting a component in the upper levels of the pathway. Through a set of investigations we identify heterotrimeric G proteins and regulation of Wnt endocytosis as the likely target of suramin in this pathway. G protein-dependent endocytosis of plasma membrane-located components of the Wnt pathway was previously shown to be important for amplification of the signal in this cascade. Our data identify endocytic regulation within Wnt signalling as a promising target for anti-Wnt and anti-cancer drug discovery. Suramin, as the first example of such drug or its analogues might pave the way for the appearance of first-in-class targeted therapies against TNBC and other Wnt-dependent cancers

Targeting the Wnt pathways for therapies

The Wnt/β-catenin signaling pathway is crucial in animal development from sponges to humans. Its activity in the adulthood is less general, with exceptions having huge medical importance. Namely, improper activation of this pathway is carcinogenic in many tissues, most notably in the colon, liver and the breast. On the other hand, the Wnt/β-catenin signaling must be re-activated in cases of tissue damage, and insufficient activation results in regeneration failure and degeneration. These both medically important implications are unified by the emerging importance of this signaling pathway in the control of proliferation of various types of stem cells, crucial for tissue regeneration and, in case of cancer stem cells - cancer progression and relapse. This article aims at briefly reviewing the current state of knowledge in the field of Wnt signaling, followed by a detailed discussion of current medical developments targeting distinct branches of the Wnt pathway for anti-cancer and pro-regeneration therapies

The downregulation of the miniature gene does not replicate miniature loss-of-function phenotypes in Drosophila melanogaster wing to the full extent

During maturation Drosophila wing epithelial cells undergo number of changes due to processes, which take place in the wing of the newly emerged fly, among which epithelial­to­mesenchymal transition (EMT) and apoptosis are pivotal. It is considered that neurohormone bursicon is responsible for their triggering. In turn, extracellular matrix protein Miniature is also essential for proper progress of apoptosis and, presumably, EMT. In accordance with our previously proposed hypothesis, Miniature and bursicon form stabilizing/accumulative complexes, which are able to diffuse freely within Drosophila wing, in such a way constitutively promoting enough concentrations of the maturation triggering signal. Here we tried to come to confirmation of our hypothesis from the other side, using UAS/GAL4 system and RNAi­silencing techniques.Клетки эпителия крыла дрозофилы во время матурации претерпевают ряд изменений как следствие происходящих в это время в крыле мухи процессов, ключевыми из которых являются эпителиально-мезенхимальный переход (ЭМП) и апоптоз. Считается, что нейрогормон бурсикон ответствен за их запуск. В свою очередь белок внеклеточного матрикса Miniature также необходим для успешного прохождения апоптоза и, вероятно, ЭМП. Согласно предложенной нами ранее гипотезе Miniature и бурсикон формируют стабилизирующие/накопительные комплексы, которые способны свободно диффундировать в плоскости крыла, постоянно поддерживая тем самым достаточную для запуска процессов матурации концентрацию сигнала.Під час матурації клітини епітелію крила дрозофіли зазнають ряд змін за рахунок процесів, які відбуваються в цей час в крилі мухи, ключовими з яких є епітеліально-мезенхімальний перехід (ЕМП) та апоптоз. Вважається, що нейрогормон бурсикон відповідальний за їхній запуск. В свою чергу білок позаклітинного матриксу Miniature також є необхідним для успішного проходження апоптозу і, ймовірно, ЕМП. Відповідно до запропонованої нами раніше гіпотези Miniature та бурсикон формують стабілізуючі/накопичувальні комплекси, які здатні вільно дифундувати в площі крила, постійно підтримуючи тим самим достатню для запуску процесів матурації концентрацію сигналу

A Second WNT for Old Drugs: Drug Repositioning against WNT-Dependent Cancers.

Aberrant WNT signaling underlies cancerous transformation and growth in many tissues, such as the colon, breast, liver, and others. Downregulation of the WNT pathway is a desired mode of development of targeted therapies against these cancers. Despite the urgent need, no WNT signaling-directed drugs currently exist, and only very few candidates have reached early phase clinical trials. Among different strategies to develop WNT-targeting anti-cancer therapies, repositioning of existing drugs previously approved for other diseases is a promising approach. Nonsteroidal anti-inflammatory drugs like aspirin, the anti-leprotic clofazimine, and the anti-trypanosomal suramin are among examples of drugs having recently revealed WNT-targeting activities. In total, 16 human-use drug compounds have been found to be working through the WNT pathway and show promise for their prospective repositioning against various cancers. Advances, hurdles, and prospects of developing these molecules as potential drugs against WNT-dependent cancers, as well as approaches for discovering new ones for repositioning, are the foci of the current review

Identification of novel elements of the Drosophila blisterome sheds light on potential pathological mechanisms of several human diseases.

Main developmental programs are highly conserved among species of the animal kingdom. Improper execution of these programs often leads to progression of various diseases and disorders. Here we focused on Drosophila wing tissue morphogenesis, a fairly complex developmental program, one of the steps of which - apposition of the dorsal and ventral wing sheets during metamorphosis - is mediated by integrins. Disruption of this apposition leads to wing blistering which serves as an easily screenable phenotype for components regulating this process. By means of RNAi-silencing technique and the blister phenotype as readout, we identify numerous novel proteins potentially involved in wing sheet adhesion. Remarkably, our results reveal not only participants of the integrin-mediated machinery, but also components of other cellular processes, e.g. cell cycle, RNA splicing, and vesicular trafficking. With the use of bioinformatics tools, these data are assembled into a large blisterome network. Analysis of human orthologues of the Drosophila blisterome components shows that many disease-related genes may contribute to cell adhesion implementation, providing hints on possible mechanisms of these human pathologies

Role of Go/i subgroup of G proteins in olfactory signaling of Drosophila melanogaster.

Intracellular signaling in insect olfactory receptor neurons remains unclear, with both metabotropic and ionotropic components being discussed. Here, we investigated the role of heterotrimeric Go and Gi proteins using a combined behavioral, in vivo and in vitro approach. Specifically, we show that inhibiting Go in sensory neurons by pertussis toxin leads to behavioral deficits. We heterologously expressed the olfactory receptor dOr22a in human embryonic kidney cells (HEK293T). Stimulation with an odor led to calcium influx, which was amplified via calcium release from intracellular stores. Subsequent experiments indicated that the signaling was mediated by the Gβγ subunits of the heterotrimeric Go/i proteins. Finally, using in vivo calcium imaging, we show that Go and Gi contribute to odor responses both for the fast (phasic) as for the slow (tonic) response component. We propose a transduction cascade model involving several parallel processes, in which the metabotropic component is activated by Go and Gi , and uses Gβγ

Mode of interaction of the Gαo subunit of heterotrimeric G proteins with the GoLoco1 motif of Drosophila Pins is determined by guanine nucleotides.

Drosophila GoLoco motif-containing protein Pins is unusual in its highly efficient interaction with both GDP- and the GTP-loaded forms of the α-subunit of the heterotrimeric Go protein. We analysed the interactions of Gαo in its two nucleotide forms with GoLoco1-the first of the three GoLoco domains of Pins-and the possible structures of the resulting complexes, through combination of conventional fluorescence and FRET measurements as well as through molecular modelling. Our data suggest that the orientation of the GoLoco1 motif on Gαo significantly differs between the two nucleotide states of the latter. In other words, a rotation of the GoLoco1 peptide in respect with Gαo must accompany the nucleotide exchange in Gαo. The sterical hindrance requiring such a rotation probably contributes to the guanine nucleotide exchange inhibitor activity of GoLoco1 and Pins as a whole. Our data have important implications for the mechanisms of Pins regulation in the process of asymmetric cell divisions

Towards the first targeted therapy for triple-negative breast cancer: Repositioning of clofazimine as a chemotherapy-compatible selective Wnt pathway inhibitor.

Wnt signaling is overactivated in triple-negative breast cancer (TNBC) and several other cancers, and its suppression emerges as an effective anticancer treatment. However, no drugs targeting the Wnt pathway exist on the market nor in advanced clinical trials. Here we provide a comprehensive body of preclinical evidence that an anti-leprotic drug clofazimine is effective against TNBC. Clofazimine specifically inhibits canonical Wnt signaling in a panel of TNBC cells in vitro. In several mouse xenograft models of TNBC, clofazimine efficiently suppresses tumor growth, correlating with in vivo inhibition of the Wnt pathway in the tumors. Clofazimine is well compatible with doxorubicin, exerting additive effects on tumor growth suppression, producing no adverse effects. Its excellent and well-characterized pharmacokinetics profile, lack of serious adverse effects at moderate (yet therapeutically effective) doses, its combinability with cytotoxic therapeutics, and the novel mechanistic mode of action make clofazimine a prime candidate for the repositioning clinical trials. Our work may bring forward the anti-Wnt targeted therapy, desperately needed for thousands of patients currently lacking targeted treatments

Miniature as a hypothetical regulatory protein of the Bursicon/Rickets signaling cascade in the wing epithelia of Drosophila melanogaster

Soon after eclosion, epithelial cells of the Drosophila wing undergo a number of the processes due to a release of the neurohormone bursicon and its further binding to the GPCR Rickets, collectively referred to as wing maturation. Here we propose hypothetical models of the interaction between extracellular Miniature, and also Dusky, proteins and proteins responsible for triggering of the wing maturation processes in Drosophila melanogaster. Keywords: bursicon, Rickets, Miniature, Dusky, wing maturation.Відразу після вилуплення з пупарію в крилі дрозофіли відбувається низка процесів під загальною назвою матурація, які запускаються нейрогормоном бурсиконом та його рецептором Rickets. В огляді представлено гіпотетичні моделі взаємодії білків позаклітинного матриксу Miniature, а також Dusky, які є необхідними як на ранніх стадіях формування крила, так і після вилуплення мухи, з білками, відповідальними за запуск процесів матурації крила у D. melanogaster. Ключові словаs: бурсикон, Rickets, Miniature, Dusky, матурація крила.Сразу после вылупления из пупария в крыле дрозофилы происходит ряд процессов под общим названием матурация, запускаемых нейрогормоном бурсиконом и его рецептором Rickets. В обзоре представлены гипотетические модели взаимодействия белков внеклеточного матрикса Miniature, а также Dusky, необходимых как на ранних стадиях формирования крыла, так и после вылупления мухи, с белками, ответственными за запуск процесов матурации крыла у D. melanogaster. Ключевые слова: бурсикон, Rickets, Miniature, Dusky, матурация крыла