C24‐Ceramide Drives Gallbladder Cancer Progression Through Directly Targeting Phosphatidylinositol 5‐Phosphate 4‐Kinase Type‐2 Gamma to Facilitate Mammalian Target of Rapamycin Signaling Activation

Abstract

Background and Aims The wide prevalence of chemoresistance and compromised early diagnosis of gallbladder cancer (GBC) has led to poor patient prognosis, requiring sustained efforts for the identification of effective biomarkers and therapeutic intervention. Ceramides have emerged as intracellular signaling molecules linked to tumorigenesis and therapeutic response in cancers. However, the clinical relevance of ceramides with GBC has not been investigated. Approach and Results In the present study, we revealed aberrant gene expressions (e.g., serine palmitoyltransferase 1 [SPTLC1] and ceramide synthase 2 [CERS2]) of de novo ceramide biosynthesis and length‐specific ceramide production in GBC tissues. Analyses of serum ceramide pattern in healthy controls, gallbladder stone, and GBC patients identified C24‐Ceramide as a potential diagnostic biomarker for patients with GBC. Importantly, elevation of SPTLC1, CERS2, and its product, C24‐Ceramide, was associated with tumor staging, distal metastasis, and worse prognosis. In line with this, C24‐Ceramide promoted GBC cell proliferation and migration in vitro and in vivo. Mechanistically, C24‐Ceramide directly bound to phosphatidylinositol 5‐phosphate 4‐kinase type‐2 gamma (PIP4K2C), a regulator of mammalian target of rapamycin (mTOR), to facilitate mTOR complex formation and activation. C6‐Ceramide, an analogue of natural ceramide, competed with C24‐Ceramide for PIP4K2C binding, thereby abrogating C24‐Ceramide–mediated mTOR signaling activation and oncogenic activity. Furthermore, stimulation with C6‐Ceramide significantly suppressed the proliferative and metastatic capacity of GBC cells in vitro and in vivo, which was dependent on PIP4K2C. Conclusions Our findings highlight the clinical relevance of ceramide metabolism with GBC progression and identify C24‐Ceramide as a diagnostic biomarker for GBC. We propose that PIP4K2C is indispensable for C6‐Ceramide as a potential therapeutic intervention for GBC through a direct competition with C24‐Ceramide.

Ceramide synthase 2‐C 24:1 ‐ceramide axis limits the metastatic potential of ovarian cancer cells

“…26 Indeed, extensive studies have uncovered specific biological roles of ceramide species including C 16 -ceramide, 27,44-47 C 18 -ceramide, 48 and C 24ceramide. 9 Therefore, this study discloses a function for C 24:1 ceramide that is quite distinct from that of C 16 -ceramide, consistent with the many ceramides hypothesis.…”

“…Recently, some studies have proposed specific roles for distinct ceramide species in cell pathobiology. 9,26,27 We investigated the roles of ceramide species in the formation of lamellipodia. In CerSs-knocked down cells, the cellular sphingolipid profile for ceramides, and their derivatives such as sphingomyelins and hexosylceramides were determined.…”

“…Phosphatidyl-3-kinase (PI3K) plays a key role in transducing cell motility-stimulating signals through tyrosine kinase receptors such as epidermal growth factor receptor and G protein-coupled receptors for lysophosphatidic acid and chemokines. [7][8][9] However, the regulatory mechanisms remain poorly understood.…”

The Role of Sphingolipids in Cancer Immunotherapy

“…First, the enhanced synthesis of Cer, in addition to S1P and glucosylceramide, is a tool employed by cancer cells to increase survival [ 46 ]. Short chain Cers such as C2 Cer and C6 Cer have been demonstrated to be involved in the modulation of immunocytes and in the proinflammatory responses [ 54 , 55 ]. Moreover, in inflammatory diseases, sphingolipids are able to act as anti- or pro-inflammatory mediators and participate in controlling leukocyte activation and migration.…”

Ceramide Metabolism Enzymes—Therapeutic Targets against Cancer

“…In particular, many inflammatory processes and pathologies, including cardiovascular diseases, neurodegenerative disorders, lung inflammatory disorders (such as chronic obstructive pulmonary disease (COPD) or asthma) type 2 diabetes or cancer, are characterized by disruption of sphingolipid homeostasis [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. Moreover, it has been reported that treatment with short-chain Cer anologs is an effective treatment against certain cancers [ 22 , 23 , 24 ]. In addition, deoxy-sphingolipids have been shown to be of great importance when observing their potential as regulators of sphingolipid metabolism.…”