BHMPS Inhibits Breast Cancer Migration and Invasion by Disrupting Rab27a-Mediated EGFR and Fibronectin Secretion

Abstract

Our previous work demonstrated that (E)-N-benzyl-6-(2-(3, 4-dihydroxybenzylidene) hydrazinyl)-N-methylpyridine-3-sulfonamide (BHMPS), a novel synthetic inhibitor of Rab27aSlp(s) interaction, suppresses tumor cell invasion and metastasis. Here, we aimed to further investigate the mechanisms of action and biological significance of BHMPS. BHMPS decreased the expression of epithelial-mesenchymal transition transcription factors through inhibition of focal adhesion kinase and c-Jun N-terminal kinase activation, thereby reducing the migration and invasion of breast cancer. Additionally, knockdown of Rab27a inhibited tumor migration, with changes in related signaling molecules, whereas overexpression of Rab27a reversed this phenomenon. BHMPS effectively prevented the interaction of Rab27a and its effector Slp4, which was verified by co-localization, immunoprecipitation, and in situ proximity ligation assays. BHMPS decreased the secretion of epidermal growth factor receptor and fibronectin by interfering with vesicle trafficking, as indicated by increased perinuclear accumulation of CD63-positive vesicles. Moreover, administration of BHMPS suppressed tumor growth in Rab27a-overexpressing MDA-MB-231 xenograft mice. These findings suggest that BHMPS may be a promising candidate for attenuating tumor migration and invasion by blocking Rab27a-mediated exocytosis.

Exosome biogenesis: machinery, regulation, and therapeutic implications in cancer

“…Slp4 (also known as granuphilin) interacts with Rabs via its N-terminal Slp homology domain and binds to SNARE complex via a central linker region [108]. Park et al reported that disrupting the interaction between Rab27a and Slp4 with inhibitor BHMPS reduced exosome secretion and inhibited tumor growth of breast cancer cells [109]. Munc13-4 is another effector of Rab27.…”

“…The mechanism of MVB transport and fusion with the plasma membrane can also be exploited by cancer. Rab27a/b are aberrantly expressed in cancers, and they have a key function in cancer progression via their activity in exosome biogenesis [109,153]. In addition, depletion of elements that mediates ER-endosome contact sites or invadopodia formation, such as Rab7, Protrudin, FYCO1, fascin-1, and cortactin, blocks exosome biogenesis and inhibits invasion in NSCLC and breast cancer [104,129,132].…”

“…Notably, (E)-N-benzyl-6-(2-(3, 4-dihydroxybenzylidene) hydrazinyl)-N-methylpyridine-3-sulfonamide (BHMPS) is a novel Rab27a inhibitor that specifically disrupts the association of Rab27a with its effector Slp4. It has been shown that BHMPS blocks exosome secretion and attenuates the invasion and migration of breast cancer [109]. Moreover, sulfisoxazole and macitentan are FDA-approved antagonists of endothelin receptor A (ETA) which regulates the expression of a series of genes associated with exosome biogenesis, such as Rab27a and Vps4B.…”

Anticancer Therapy Targeting Cancer-Derived Extracellular Vesicles

“…It has been shown that calpain inhibitors, calpeptin, and Rho-associated protein kinases (ROCK), Y27632, can block MVB formation and release by targeting cytoskeletal proteins . Apart from that, targeting Rab27-related signaling, as well as the syndecan-syntenin-Alix signaling has also shown promising outcomes in inhibiting the EVs biogenesis of cancer. , However, since the ESCRT machinery is exploited by all cells to generate EVs, interfering with ESCRT-related signaling pathways may cause severe side effects by blocking the EV-mediated cell–cell communications required for normal organ functions. As accumulated evidence suggests that highly malignant cancer cells are able to secrete more EVs compared to normal cells, there might be some alternative mechanisms for cancer cells to generate and release EVs into the extracellular space.…”

Perspective Chapter: Exosomes – The Surreptitious Intercellular Messengers in the Body

“…Rab27a and Rab27b interact with their respective effector proteins, Slp4 and Slac2b, respectively, to transfer MVBs from the perinuclear to the periphery area of the cell [25]. Abolishing these interactions leads to decreased exosome release and inhibited breast cancer cell invasion and migration [27]. Additionally, some factors such as HSP90 and lysosome-associated protein transmembrane-4B (LAPTM4B) also transfer MVBs toward the periphery to promote their secretion [28,29].…”