Stereo-specific Lasofoxifene Derivatives Reveal the Interplay between Estrogen Receptor Alpha Stability and Antagonistic Activity in ESR1 Mutant Breast Cancer Cells

Chemical manipulation of estrogen receptor alpha ligand binding domain structural mobility tunes receptor lifetime and influences breast cancer therapeutic activities. Selective estrogen receptor modulators (SERMs) extend ERα cellular lifetime, accumulation, and are antagonists in the breast and agonists in the uterine epithelium and/or in bone. Selective estrogen receptor degraders (SERDs) reduce ERα cellular lifetime/accumulation and are pure antagonists. Activating somatic ESR1 mutations Y537S and D538G enable resistance to first-line endocrine therapies. SERDs have shown significant activities in ESR1 mutant setting while few SERMs have been studied. To understand whether chemical manipulation of ERα cellular lifetime and accumulation influences antagonistic activity, we synthesized a series of methylpyrollidine lasofoxifene derivatives that maintained the drug’s antagonistic activities while uniquely tuning ERα cellular accumulation. These molecules were examined alongside a panel of antiestrogens in live cell assays of ERα cellular accumulation, lifetime, SUMOylation, and transcriptional antagonism. High-resolution x-ray crystal structures of WT and Y537S ERα ligand binding domain in complex with the methylated lasofoxifene derivatives, SERMs, and SERDs show that molecules that favor a highly buried helix 12 conformation achieve the greatest transcriptional suppression activities. Together these results show that chemical reduction of ERα cellular lifetime does not necessarily correlate with transcriptional antagonism in ESR1 mutated breast cancer cells. Importantly, our approach shows how minor chemical additions modulate receptor cellular lifetime while maintaining other activities to achieve desired SERM or SERD profiles.

Organic Cation Transporters are Involved in Fluoxetine Transport Across the Blood-Brain Barrier in Vivo and in Vitro

Background : The research and development of drugs for the treatment of central nervous system diseases faces many challenges at present. One of the most important questions to be answered is, how does the drug cross the blood-brain barrier to get to the target site for pharmacological action. Fluoxetine is widely used in clinical antidepressant therapy. However, the mechanism by which fluoxetine passes through the BBB also remains unclear. Under physiological pH conditions, fluoxetine is an organic cation with a relatively small molecular weight (<500), which is in line with the substrate characteristics of organic cation transporters (OCTs). Therefore, this study aimed to investigate the interaction of fluoxetine with OCTs at the BBB and BBB-associated efflux transporters. This is of great significance for fluoxetine to better treat depression. Moreover, it can provide a theoretical basis for clinical drug combinations. Methods: In vitro BBB model was developed using human brain microvascular endothelial cells (hCMEC/D3), and the cellular accumulation was tested in the presence or absence of transporter inhibitors. In addition, an in vivo trial was performed in rats to investigate the effect of OCTs on the distribution of fluoxetine in the brain tissue. Fluoxetine concentration was determined by a validated UPLC-MS/MS method. Results: The results showed that amantadine (an OCT1/2 inhibitor) and prazosin (an OCT1/3 inhibitor) significantly decreased the cellular accumulation of fluoxetine (P <.001). Moreover, we found that N-methylnicotinamide (an OCT2 inhibitor) significantly inhibited the cellular uptake of 100 and 500 ng/mL fluoxetine (P <.01 and P <.05 respectively). In contrast, corticosterone (an OCT3 inhibitor) only significantly inhibited the cellular uptake of 1000 ng/mL fluoxetine (P <.05). The P-glycoprotein (P-gp) inhibitor, verapamil, and the multidrug resistance resistance-associated proteins (MRPs) inhibitor, MK571, significantly decreased the cellular uptake of fluoxetine. However, intracellular accumulation of fluoxetine was not significantly changed when fluoxetine was incubated with the breast cancer resistance protein (BCRP) inhibitor Ko143. Furthermore, in vivo experiments proved that corticosterone and prazosin significantly inhibited the brain-plasma ratio of fluoxetine at 5.5 h and 12 h, respectively. Conclusion: OCTs might play a significant role in the transport of fluoxetine across the BBB. In addition, P-gp, BCRP, and MRPs seemed not to mediate the efflux transport of fluoxetine.

Improving The Accumulation Of Gold Nanoparticles Using Ultrasound And Microbubbles To Enhance Radiation Therapy

Gold nanoparticles have long been considered for use in conjunction with radiation therapy to enhance dose in a local tumor regions. However, limitation in cellular accumulation remains a hindrance for treatments to extend to clinical levels. Ultrasound and microbubbles have been shown to enhance the delivery of chemotherapies, genetic material and other molecules. This goal of this study was to demonstrate, for the first time to the best of our knowledge, the increase in PEGylated gold nanoparticle accumulation in cells due to the addition of ultrasound and microbubbles, and survival fraction. The results display approximate 3 fold increase in intracellular gold content independent of nanoparticle size, resulting in a 5 fold increase in cell death. Additionally, it was shown that USMB can facilitate nuclear localization of gold nanoparticles with nuclear localized signals to further enhance radiation therapy.

Improving The Accumulation Of Gold Nanoparticles Using Ultrasound And Microbubbles To Enhance Radiation Therapy

Gold nanoparticles have long been considered for use in conjunction with radiation therapy to enhance dose in a local tumor regions. However, limitation in cellular accumulation remains a hindrance for treatments to extend to clinical levels. Ultrasound and microbubbles have been shown to enhance the delivery of chemotherapies, genetic material and other molecules. This goal of this study was to demonstrate, for the first time to the best of our knowledge, the increase in PEGylated gold nanoparticle accumulation in cells due to the addition of ultrasound and microbubbles, and survival fraction. The results display approximate 3 fold increase in intracellular gold content independent of nanoparticle size, resulting in a 5 fold increase in cell death. Additionally, it was shown that USMB can facilitate nuclear localization of gold nanoparticles with nuclear localized signals to further enhance radiation therapy.

Iron Metabolism: From Inflammation to Cancer

Iron is a trace element essential for several physiological cell functions and any alteration in its metabolism could be associated to the onset of several disorders. Cells normally avoid any dysregulation, activating fine molecular mechanisms to balance iron uptake, utilization, recycling, storage and export. The main “actors” in this event are hepcidin, ferroportin, ferritin and transferrin, both at cell and systemic level. Dysregulation in iron homeostasis is closely related to inflammation onset and perpetuation, osteoporosis and cancer progression. During inflammation, it has been observed a reduction in circulating iron as direct consequence of increase in ferritin levels, aimed to contain inflammatory processes and in many cases to restore the immune response. Iron overload directly promotes bone resorption and inhibits bone formation inducing osteoporosis. Moreover, iron cellular accumulation is responsible for ROS production with consequent DNA damage and neoplastic transformation of cells. In conclusion, even though many molecular mechanisms have to be clarified, targeting iron and also the mediators of its metabolism could be useful to manage a great variety of disorders, such inflammation, immune diseases, osteoporosis and cancer.

N-acetylcysteine delivery with silica nanoparticles into 3T3-L1 adipocytes

Background: The addition of 5 mM N-acetylcysteine (NAC) to 3T3-L1 adipocytes culture inhibits the accumulation of triglycerides (Tg) by 50%, but after 48 h uptake was only 16% of total NAC available. Based on these results, the aim of this study is to increase the NAC cellular uptake by encapsulating it in silica nanoparticles (NPs). Materials & methods: Silica NPs, 20 ± 4.5 nm in size, were developed, with an inner cavity loaded with 5 mM NAC. At 48 h after treatment, there was a dose-dependent cytotoxic effect. We attempted to reduce the cytotoxicity of silica NPs by coating them with bovine serum albumin. Results: While we obtained nontoxic bovine serum albumin coated NPs, their effect on Tg cellular accumulation was also reduced.

The Biological Roles of lncRNAs and Future Prospects in Clinical Application

Chemo and radiation therapies are the most commonly used therapies for cancer, but they can induce DNA damage, resulting in the apoptosis of host cells. DNA double-stranded breaks (DSBs) are the most lethal form of DNA damage in cells, which are constantly caused by a wide variety of genotoxic agents, both environmentally and endogenously. To maintain genomic integrity, eukaryotic organisms have developed a complex mechanism for the repair of DNA damage. Researches reported that many cellular long noncoding RNAs (lncRNAs) were involved in the response of DNA damage. The roles of lncRNAs in DNA damage response can be regulated by the dynamic modification of N6-adenosine methylation (m6A). The cellular accumulation of DNA damage can result in various diseases, including cancers. Additionally, lncRNAs also play roles in controlling the gene expression and regulation of autophagy, which are indirectly involved with individual development. The dysregulation of these functions can facilitate human tumorigenesis. In this review, we summarized the origin and overview function of lncRNAs and highlighted the roles of lncRNAs involved in the repair of DNA damage.