SN 2

Synthetic Lethality Exploitation by an Anti-Trop-2-SN-38 Antibody-Drug Conjugate, IMMU-132, Plus PARP Inhibitors in BRCA1/2-wild-type Triple-Negative Breast Cancer.[Pubmed:28069724]

Clin Cancer Res. 2017 Jul 1;23(13):3405-3415.

Purpose: Both PARP inhibitors (PARPi) and sacituzumab govitecan (IMMU-132) are currently under clinical evaluation in triple-negative breast cancer (TNBC). We sought to investigate the combined DNA-damaging effects of the topoisomerase I (Topo I)-inhibitory activity of IMMU-132 with PARPi disruption of DNA repair in TNBC.Experimental Design:In vitro, human TNBC cell lines were incubated with IMMU-132 and various PARPi (olaparib, rucaparib, or talazoparib) to determine the effect on growth, double-stranded DNA (dsDNA) breaks, and cell-cycle arrest. Mice bearing BRCA1/2-mutated or -wild-type human TNBC tumor xenografts were treated with the combination of IMMU-132 and PARPi (olaparib or talazoparib). Study survival endpoint was tumor progression to >1.0 cm(3) and tolerability assessed by hematologic changes.Results: Combining IMMU-132 in TNBC with all three different PARPi results in synergistic growth inhibition, increased dsDNA breaks, and accumulation of cells in the S-phase of the cell cycle, regardless of BRCA1/2 status. A combination of IMMU-132 plus olaparib or talazoparib produces significantly improved antitumor effects and delay in time-to-tumor progression compared with monotherapy in mice bearing BRCA1/2-mutated HCC1806 TNBC tumors. Furthermore, in mice bearing BRCA1/2-wild-type tumors (MDA-MB-468 or MDA-MB-231), the combination of IMMU-132 plus olaparib imparts a significant antitumor effect and survival benefit above that achieved with monotherapy. Most importantly, this combination was well tolerated, with no substantial changes in hematologic parameters.Conclusions: These data demonstrate the added benefit of combining Topo I inhibition mediated by IMMU-132 with synthetic lethality provided by PARPi in TNBC, regardless of BRCA1/2 status, thus supporting the rationale for such a combination clinically. Clin Cancer Res; 23(13); 3405-15. (c)2017 AACR.

An efficient Sn(ii)-catalyzed one-pot synthesis of a 3-substituted azetidine-2,4-dione framework.[Pubmed:28244538]

Org Biomol Chem. 2017 Mar 21;15(11):2385-2391.

A novel Sn(ii)-catalyzed tandem cyclization reaction of aromatic aldehydes with ethyl cyanoacetate has been achieved to afford a series of 3-substituted azetidine-2,4-diones in good to excellent yields. This protocol provides straightforward access to construct the azetidine core through sequential Knoevenagel condensation, hydration and the C-N cyclization reaction.

alpha-Melt Structure of 1,3-Dipalmitoyl-2-oleoyl-sn-glycerol (POP) under a Thermal Thawing Process Studied by Infrared Spectroscopy.[Pubmed:28070080]

Anal Sci. 2017;33(1):75-78.

The temperature thawing, as called tempering, of triacylglycerols (TAGs) is an important processing method in food productions, such as chocolates, cream, confections, and spreads. Especially, melt-mediation by temperature thawing is famous in chocolate production for controlling the polymorphic crystalline forms and accelerating crystallization. In the present study, we investigated the alpha-melt structure of 1,3-dipalmitoyl-2-oleoyl-sn-glycerol (POP), one of the major continuants of cacao butter, under a phase transition from its melt to gamma-crystal with in-situ attenuated total reflection-infrared (ATR-IR) spectroscopy. The differential IR spectrum between alpha-melt via temperature thawing (alpha-melt mediation) and melt via simple cooling revealed that crystal-like local ordered structures remained in part in the alpha-melt, and that they acted as nuclei for a rapid phase transition to the gamma-crystal. The changes to the gamma-crystal occur in the local ordered structures at first from the glycerol moiety to the acyl chains in the crystallization, providing an important suggestion concerning the mechanism for the acceleration of crystallization to the gamma-form via alpha-melt mediation.

Biomimetic nanoassemblies of 1-O-octodecyl-2-conjugated linoleoyl-sn-glycero-3-phosphatidyl gemcitabine with phospholipase A2-triggered degradation for the treatment of cancer.[Pubmed:28187380]

Colloids Surf B Biointerfaces. 2017 Apr 1;152:467-474.

Phospholipids are important biomolecules with strong self-assembling ability to form biomembranes or liposomes. However, biomimetic prodrugs of phospholipids are not well known, including their self-assembling behavior at the air/water interface or in aqueous media. Here we design and prepare a biomimetic phospholipid-like amphiphilic prodrug, 1-O-octodecyl-2-conjugated linoleoyl-sn-glycero-3-phosphatidyl gemcitabine (OLGPG). After spreading at the air/water interface, it formed Langmuir monolayers. Stable nanoassemblies were obtained based on molecular self-assembly after OLGPG was injected in water. An amphiphilic long-chained lipid, cholesteryl hemisuccinate polyethylene glycol 1500 (CHS-PEG) was mixed in the OLGPG Langmuir monolayers and nanoassemblies with the optimal proportion. The OLGPG and OLGPG/CHS-PEG nanoassemblies were spherical vesicles due to the hydrophobic interaction of lipid moieties with the small sizes of 50.33nm and 64.76nm, respectively. Phospholipase A2 (PLA2) is highly expressed in tumor tissues to specifically degrade the 2-acyl of phospholipid to lysophospholipid. OLGPG showed PLA2-sensitive degradation. The nanoassemblies showed higher in vitro anticancer effect on HepG2 cells than the parent drug gemcitabine. In the in vivo studies on the hepatocellular tumor-bearing mouse model, the OLGPG/CHS-PEG nanoassemblies group (eq. to 1/5 dose of the Gem group) showed the highest antitumor and tumor targeting effects compared to the other groups. The long-circulating phospholipid-like prodrug nanoassemblies are the promising anticancer nanomedicines based on the biomimetic strategy and specific tumor microenvironment.

Small molecule activators of TRPML3.[Pubmed:20189104]

Chem Biol. 2010 Feb 26;17(2):135-48.

We conducted a high-throughput screen for small molecule activators of the TRPML3 ion channel, which, when mutated, causes deafness and pigmentation defects. Cheminformatics analyses of the 53 identified and confirmed compounds revealed nine different chemical scaffolds and 20 singletons. We found that agonists strongly potentiated TRPML3 activation with low extracytosolic [Na(+)]. This synergism revealed the existence of distinct and cooperative activation mechanisms and a wide dynamic range of TRPML3 activity. Testing compounds on TRPML3-expressing sensory hair cells revealed the absence of activator-responsive channels. Epidermal melanocytes showed only weak or no responses to the compounds. These results suggest that TRPML3 in native cells might be absent from the plasma membrane or that the protein is a subunit of heteromeric channels that are nonresponsive to the activators identified in this screen.

Genetic inactivation of Trpml3 does not lead to hearing and vestibular impairment in mice.[Pubmed:21179200]

PLoS One. 2010 Dec 13;5(12):e14317.

TRPML3, a member of the transient receptor potential (TRP) family, is an inwardly rectifying, non-selective Ca2+-permeable cation channel that is regulated by extracytosolic Na+ and H+ and can be activated by a variety of small molecules. The severe auditory and vestibular phenotype of the TRPML3(A419P) varitint-waddler mutation made this protein particularly interesting for inner ear biology. To elucidate the physiological role of murine TRPML3, we conditionally inactivated Trpml3 in mice. Surprisingly, lack of functional TRPML3 did not lead to circling behavior, balance impairment or hearing loss.