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The first total synthesis of (–)-merrillianin (1), which is a natural sesquiterpene with a tri- fused structure having a cyclopentane ring and five- and seven-membered lactone parts, is demonstrated. This asymmetric total synthesis enabled the absolute stereo structure determination of naturally occurring (–)-1.

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The Golgi apparatus is responsible for transporting, processing, and sorting numerous proteins in the cell, including cell surface-expressed receptor tyrosine kinases (RTK). The small-molecule compound M-COPA [2-methylcoprophilinamide (AMF-26)] disrupts the Golgi apparatus by inhibiting the activation of Arf1, resulting in suppression of tumor growth. Here, we report an evaluation of M-COPA activity against RTK-addicted cancers, focusing specifically on human gastric cancer (GC) cells with or without MET amplification. As expected, the MET-addicted cell line MKN45 exhibited a better response to M-COPA than cell lines without MET amplification. Upon M-COPA treatment, cell surface expression of MET was downregulated with a concurrent accumulation of its precursor form. M-COPA also reduced levels of the phosphorylated form of MET along with the downstream signaling molecules Akt and S6. Similar results were obtained in additional GC cell lines with amplification of MET or the FGF receptor FGFR2. MKN45 murine xenograft experiments demonstrated the antitumor activity of M-COPA in vivo. Taken together, our results offer an initial preclinical proof of concept for the use of M-COPA as a candidate treatment option for MET-addicted GC, with broader implications for targeting the Golgi apparatus as a novel cancer therapeutic approach. Cancer Res; 76(13); 3895–903. ©2016 AACR.

The antibodies used in this study.

Supplemental Materials and Methods for "Authentication of cell lines"

Dose-dependent effects on cell surface expression and processing of MET protein, and phosphorylation status of downstream signaling molecules.

The effect of M-COPA on cell surface expression of BCRP1 and P-glycoprotein (MDR1).

Effect of M-COPA on cell surface expression of EGFR in MET-unamplified GC cell lines.

Effect of M-COPA on cell surface expression and phosphorylation status of HER3 in MKN-45 cells.

The first total synthesis of (+)-tanzawaic acid B, a natural polyketide bearing a pentadienoic ester and octalin moiety, has been accomplished. The synthetic improvement from previous synthetic conditions facilitated our gram-scale synthesis of the chiral octalin that possesses seven stereogenic centers and that is the core skeleton of almost all of the tanzawaic acid family.

SUMMARYMost gastrointestinal stromal tumors (GISTs) develop due to gain-of-function mutations in the tyrosine kinase,KIT. We recently showed that mutant KIT mislocalizes to the Golgi area and initiates uncontrolled signaling. However, the molecular mechanisms underlying its Golgi retention remain unknown. Here, we show that protein kinase D2 (PKD2) is activated by the mutant, which causes KIT’s Golgi retention. In PKD2-inhibited cells, KIT migrates from the Golgi region to lysosomes and subsequently undergoes degradation. Importantly, delocalized KIT is unable to trigger downstream activation. In the Golgi area, KIT activates the PKD2-phosphatidylinositol 4-kinaseIIIβ (PKD2-PI4KIIIβ) pathway through phospholipase γ2 (PLCγ2) to generate a PI4P-rich membrane domain, where the AP1-GGA1 complex is aberrantly recruited. Disruption of any factors in this cascade results in KIT release from the Golgi region, indicating that these PKD2-related pathways are responsible for the Golgi retention of KIT. Our findings unveil the molecular mechanisms underlying KIT mislocalization and provide evidence for a new strategy for inhibition of oncogenic signaling.

The first total synthesis of (+)-tanzawaic acid B, a natural polyketide bearing a pentadienoic ester and octalin moiety, has been accomplished. The synthetic improvement from previous synthetic conditions facilitated our gram-scale synthesis of the chiral octalin that possesses seven stereogenic centers and that is the core skeleton of almost all of the tanzawaic acid family.