Synthetic Indolactam V Analogues as Inhibitors of PAR2-Induced Calcium Mobilization in Triple-Negative Breast Cancer Cells

Total Syntheses of Indole Terpenoids (-)-Lyngbyatoxin, (-)-Teleocidin A2, and (-)-7-Geranylindolactam V

A regiodivergent palladium-catalyzed Suzuki-Miyaura reaction has been successfully implemented to synthesize (-)-lyngbyatoxin, (-)-teleocidin A2, and (-)-7-geranylindolactam V. This ligand-controlled cross-coupling strategy allowed for the direct preparation of these natural products from a single advanced synthetic intermediate, providing the shortest reported route to each compound. Subsequent in vitro studies in cancer cell lines were conducted to explore the chemotherapeutic applications of these natural products.

FVIIa-PAR2 signaling facilitates immune escape by reducing phagocytic potential of macrophages in breast cancer

BACKGROUND

Treatment of breast cancers with immunotherapy has so far achieved limited success. Traditional immunotherapies focusing on cytotoxic T cells have attained modest success, while the approval of phagocytic checkpoint blockers is still pending. Coagulation proteases are crucial to cancer growth and proliferation, but their relevance in altering the immunologic topography in tumors remains largely unknown.

OBJECTIVES

In this study, we aimed to examine whether factor VIIa (FVIIa)-driven protease-activated receptor 2 (PAR2) activation and its subsequent signaling pathways assist cancer cells in evading phagocytic macrophages.

METHODS

Peripheral blood mononuclear cell- or THP-1-derived macrophages were cocultured with MDA-MB-468 cells that were pretreated with or without FVIIa. The phagocytic activity of macrophages was assessed through flow cytometry and immunofluorescence. Additionally, an allograft model using wild-type and PAR2-deleted 4T1 cells was employed to investigate the impact of PAR2 activation on immune escape from macrophages in vivo.

RESULTS

We found evidence that FVIIa-induced PAR2 cleavage activates downstream signaling cascades and augments cellular levels of microRNA221, which transcriptionally activates both CD47 and stanniocalcein 1 expression, thereby assisting the escape from phagocytosis by macrophages. Stanniocalcein 1 decreases the surface expression of calreticulin, a dominant prophagocytic signal, thereby tilting it in favor of phagocytic evasion. Mouse models using PAR2-depleted cells displayed smaller tumor volumes and corresponding greater phagocytic events when combined with anti-CD47/anti-PD-L1 antibodies.

CONCLUSION

PAR2 signaling initiates an intrinsic mechanism of immune escape by diminishing phagocytosis of cancer cells.

Biological evaluation of indolactams for in vitro bryostatin 1-like activity

Small molecule activators of protein kinase C (PKC) have traditionally been classified as either tumor promoters or suppressors. Although bryostatin 1 has well established anti-cancer activity, most natural products that target the PKC regulator domain exhibit tumor promotion properties. In this study, we examine a focused library of indolactam analogues in cell-based assays to establish the structural features of the scaffold that enhance bryostatin 1-like activity. These systematic biological assessments identified specific indole substitution patterns that impart diminished tumor promotion behavior in vitro for indolactam analogues, while still maintaining nanomolar potency for PKC.

Stationed or Relocating: The Seesawing EMT/MET Determinants from Embryonic Development to Cancer Metastasis

Epithelial and mesenchymal transition mechanisms continue to occur during the cell cycle and throughout human development from the embryo stage to death. In embryo development, epithelial-mesenchymal transition (EMT) can be divided into three essential steps. First, endoderm, mesoderm, and neural crest cells form, then the cells are subdivided, and finally, cardiac valve formation occurs. After the embryonic period, the human body will be subjected to ongoing mechanical stress or injury. The formation of a wound requires EMT to recruit fibroblasts to generate granulation tissues, repair the wound and re-create an intact skin barrier. However, once cells transform into a malignant tumor, the tumor cells acquire the characteristic of immortality. Local cell growth with no growth inhibition creates a solid tumor. If the tumor cannot obtain enough nutrition in situ, the tumor cells will undergo EMT and invade the basal membrane of nearby blood vessels. The tumor cells are transported through the bloodstream to secondary sites and then begin to form colonies and undergo reverse EMT, the so-called "mesenchymal-epithelial transition (MET)." This dynamic change involves cell morphology, environmental conditions, and external stimuli. Therefore, in this manuscript, the similarities and differences between EMT and MET will be dissected from embryonic development to the stage of cancer metastasis.

Synthesis of N-indolated amino acids or peptides from 2-alkynylanilines via a dearomatization process

A process for the rapid synthesis of N-indolated amino acids or peptides from readily available 2-alkynylanilines via dearomatization was reported.

GPCR Modulation in Breast Cancer

Breast cancer is the most prevalent cancer found in women living in developed countries. Endocrine therapy is the mainstay of treatment for hormone-responsive breast tumors (about 70% of all breast cancers) and implies the use of selective estrogen receptor modulators and aromatase inhibitors. In contrast, triple-negative breast cancer (TNBC), a highly heterogeneous disease that may account for up to 24% of all newly diagnosed cases, is hormone-independent and characterized by a poor prognosis. As drug resistance is common in all breast cancer subtypes despite the different treatment modalities, novel therapies targeting signaling transduction pathways involved in the processes of breast carcinogenesis, tumor promotion and metastasis have been subject to accurate consideration. G protein-coupled receptors (GPCRs) are the largest family of cell-surface receptors involved in the development and progression of many tumors including breast cancer. Here we discuss data regarding GPCR-mediated signaling, pharmacological properties and biological outputs toward breast cancer tumorigenesis and metastasis. Furthermore, we address several drugs that have shown an unexpected opportunity to interfere with GPCR-based breast tumorigenic signals.