Inhibition of Patched Drug Efflux Increases Vemurafenib Effectiveness against Resistant BrafV600E Melanoma

Patient-Derived Melanoma Immune-Tumoroids as a Platform for Precise High throughput Drug Screening

In vitro models are crucial in cancer research, but they must truthfully mimic in vivo tumors for clinical relevance. The development of unprecedent melanoma quadruple multicellular tumoroids (MCTs) is proposed comprising tumor cells, keratinocytes, fibroblasts, and monocytes that replicate tumor architecture, tumor microenvironment, and secretome behavior. These MCTs of 300 µm in diameter secreted keratin and collagen, showing complexity proportional to their cell combinations. Further, closely resembled in vivo tumors in terms of cells organization, growth, progression, and immune behavior. Drug screening using these MCTs demonstrated their potential as patient-derived platforms for precision medicine. These findings highlight the true value of MCTs for studying melanoma biology and testing therapeutic interventions with greater precision and relevance to human disease.

Melanoma redox biology and the emergence of drug resistance

Melanoma is the deadliest form of skin cancer, with the loss of approximately 60,000 lives world-wide each year. Despite the development of targeted therapeutics, including compounds that have selectivity for mutant oncoproteins expressed only in cancer cells, many patients are either unresponsive to initial therapy or their tumors acquire resistance. This results in five-year survival rates of below 25%. New strategies that either kill drug-resistant melanoma cells or prevent their emergence would be extremely valuable. Melanoma, like other cancers, has long been described as being under increased oxidative stress, resulting in an increased reliance on antioxidant defense systems. Changes in redox homeostasis are most apparent during metastasis and during the metabolic reprogramming associated with the development of treatment resistance. This review discusses oxidative stress in melanoma, with a particular focus on targeting antioxidant pathways to limit the emergence of drug resistant cells.

Carbon-coated selenium nanoparticles for photothermal therapy in choriocarcinoma cells

Choriocarcinoma can be cured by chemotherapy, but this causes resistance and severe side effects that bring about physical and psychological consequences for patients. Therefore, there is still an urgent need to find other alternative minimally invasive therapies to halt the progression of choriocarcinoma. Novel carbon-coated selenium nanoparticles (C-Se) were successfully synthesized for choriocarcinoma photothermal therapy. C-Se combined with near-infrared laser irradiation can inhibit the proliferation of human choriocarcinoma (JEG-3) cells and induce cell apoptosis. C-Se killed cells and produced ROS under near-infrared laser irradiation. Finally, the therapeutic mechanism of C-Se + laser was explored showing that C-Se + laser influenced numerous biological processes. Taken together, C-Se exhibited significant potential for choriocarcinoma photothermal therapy.

Lipid-membrane protein interaction visualised by cryo-EM: A review

Membrane proteins reside at interfaces between aqueous and lipid media and solving their molecular structure relies most of the time on removing them from the membrane using detergent. Luckily, this solubilization process does not strip them from all the associated lipids and single-particle cryo-transmission electron microscopy (SP-TEM) has proved a very good tool to visualise both protein high-resolution structure and, often, many of its associated lipids. In this review, we observe membrane protein structures from the Protein DataBank and their associated maps in the Electron Microscopy DataBase and determine how the SP-TEM maps allow lipid visualization, the type of binding sites, the influence of symmetry, resolution and other factors. We illustrate lipid visualization around and inside the protein core, show that some lipid bilayers in the core can be shifted with respect to the membrane and how some proteins can actively bend the lipid bilayer that binds to them. We conclude that resolution improvement in SP-TEM will likely enable many more discoveries regarding the role of lipids bound to proteins.

Persistent Properties of a Subpopulation of Cancer Cells Overexpressing the Hedgehog Receptor Patched

Despite the development of new therapeutic strategies, cancer remains one of the leading causes of mortality worldwide. One of the current major challenges is the resistance of cancers to chemotherapy treatments inducing metastases and relapse of the tumor. The Hedgehog receptor Patched (Ptch1) is overexpressed in many types of cancers. We showed that Ptch1 contributes to the efflux of doxorubicin and plays an important role in the resistance to chemotherapy in adrenocortical carcinoma (ACC), a rare cancer which presents strong resistance to the standard of care chemotherapy treatment. In the present study, we isolated and characterized a subpopulation of the ACC cell line H295R in which Ptch1 is overexpressed and more present at the cell surface. This cell subpopulation is more resistant to doxorubicin, grows as spheroids, and has a greater capability of clonogenicity, migration, and invasion than the parental cells. Xenograft experiments performed in mice and in ovo showed that this cell subpopulation is more tumorigenic and metastatic than the parental cells. These results suggest that this cell subpopulation has cancer stem-like or persistent cell properties which were strengthened by RNA-seq. If present in tumors from ACC patients, these cells could be responsible for therapy resistance, relapse, and metastases.

Microscale Thermophoresis to Evaluate the Functionality of Heterologously Overexpressed Membrane Proteins in Membrane Preparations

Transmembrane proteins are challenging to express in heterologous systems and to purify, thus any technique enabling to evaluate the functionality of the protein produced prior purification provides a huge step forward. Furthermore, the membrane environment may be critical for the activity of the target protein and accessing information in the membrane fragments instead of solubilizing the target into a detergent that may be unsuitable for its function is key to study and evaluate its activity. Herein, we describe how microscale thermophoresis (MST) was used to evaluate the functionality of membrane proteins directly in host membrane preparation before purification. We give a protocol to measure the affinity between the human Hedgehog (Hh) receptor Ptch1 in yeast plasma membrane and the small molecule PAH, which was shown to inhibit its drug efflux activity.

Interrogating Epigenome toward Personalized Approach in Cutaneous Melanoma

Epigenetic alterations have emerged as essential contributors in the pathogenesis of various human diseases, including cutaneous melanoma (CM). Unlike genetic changes, epigenetic modifications are highly dynamic and reversible and thus easy to regulate. Here, we present a comprehensive review of the latest research findings on the role of genetic and epigenetic alterations in CM initiation and development. We believe that a better understanding of how aberrant DNA methylation and histone modifications, along with other molecular processes, affect the genesis and clinical behavior of CM can provide the clinical management of this disease a wide range of diagnostic and prognostic biomarkers, as well as potential therapeutic targets that can be used to prevent or abrogate drug resistance. We will also approach the modalities by which these epigenetic alterations can be used to customize the therapeutic algorithms in CM, the current status of epi-therapies, and the preliminary results of epigenetic and traditional combinatorial pharmacological approaches in this fatal disease.

Molecular insights into the Patched1 drug efflux inhibitory activity of panicein A hydroquinone: a computational study

Human Hedgehog receptor Patched1 (PTCH1) is able to efflux chemotherapeutics of different chemical structure out of cancer cells thus contributing to multidrug resistance phenomena in tumor treatment. A screening of natural compounds purified from marine sponges led to the identification of the first PTCH1 efflux inhibitor, panicein A hydroquinone (PAH), demonstrated to increase doxorubicin toxicity in vitro and vemurafenib toxicity in vitro and in vivo. In this work we combined different computational techniques to gain molecular insights of the inhibitory activity of PAH and some of its active and inactive analogues. We first performed a thorough characterization and druggability analysis of the main putative substrate binding pockets known from available cryo-electron microscopy structures. Further, dynamical descriptors of the active and inactive PAH analogues were extracted from microsecond-long all-atom molecular dynamics simulations in water solution. Finally, a blind ensemble docking methodology coupled with the conformational analysis of compounds enabled rationalization of the interaction between PTCH1 and PAH and derivatives in terms of their intrinsic physico-chemical properties. Our results suggest that the Neck pocket is the preferential binding site for PAH analogues on PTCH1, and that compounds assuming an open cylindric-like shape in solution are most likely to be good binders for PTCH1.

Methiothepin Increases Chemotherapy Efficacy against Resistant Melanoma Cells

We previously reported that methiothepin, a small molecule known as a nonselective serotonin 5-HT receptor antagonist, inhibited the doxorubicin efflux activity of the Hedgehog receptor Ptch1 and enhanced the cytotoxic, pro-apoptotic, anti-proliferative, and anti-clonogenic effects of doxorubicin on adrenocortical carcinoma cells. Here, we show that methiothepin also inhibits doxorubicin efflux and increases doxorubicin cytotoxicity in melanoma cells which endogenously overexpress Ptch1. Melanoma patients having the BRAF^V600E mutation are treated with vemurafenib, an inhibitor of BRAF^V600E, often in combination with trametinib, an inhibitor of MEK. Almost all patients ultimately acquire resistance to the treatment leading to disease progression. Here, we report that methiothepin overcomes the resistance of BRAF^V600E melanoma cells by enhancing the cytotoxicity of vemurafenib and trametinib on these cells leading to melanoma cells death. We observe that the addition of methiothepin to vemurafenib prevents migration of resistant melanoma cells more efficiently than vemurafenib alone. Our results provide an additional proof that Ptch1 drug efflux inhibition increases the effectiveness of anti-cancer treatments and overcomes resistance of melanoma cells expressing Ptch1.

Astemizole Sensitizes Adrenocortical Carcinoma Cells to Doxorubicin by Inhibiting Patched Drug Efflux Activity

Adrenocortical carcinoma (ACC) presents a high risk of relapse and metastases with outcomes not improving despite extensive research and new targeted therapies. We recently showed that the Hedgehog receptor Patched is expressed in ACC, where it strongly contributes to doxorubicin efflux and treatment resistance. Here, we report the identification of a new inhibitor of Patched drug efflux, the anti-histaminergic drug astemizole. We show that astemizole enhances the cytotoxic, proapoptotic, antiproliferative and anticlonogenic effects of doxorubicin on ACC cells at concentrations of astemizole or doxorubicin that are not effective by themselves. Our results suggest that a low concentration of astemizole sensitizes ACC cells to doxorubicin, which is a component of the standard treatment for ACC composed of etoposide, doxorubicin, cisplatin and mitotane (EDPM). Patched uses the proton motive force to efflux drugs. This makes its function specific to cancer cells, thereby avoiding toxicity issues that are commonly observed with inhibitors of ABC multidrug transporters. Our data provide strong evidence that the use of astemizole or a derivative in combination with EDPM could be a promising therapeutic option for ACC by increasing the treatment effectiveness at lower doses of EDPM, which would reduce the severe side effects of this regimen.