Pancreatic cancer (PC) is a devastating solid malignancy with a dismal prognosis. The treatment of metastatic PC is a current challenge for medical oncologists due to a lack of early detection, drug resistance, and relapse. Therefore, potential biomarkers and effective therapeutic targets for PC are urgently required. Ceramide-1-phosphate transfer protein (CPTP) is a member of the glycolipid transfer protein family, which is associated with autophagy and inflammation regulation. The roles and mechanisms of CPTP in PC have not been clarified. In this study, by RT-qPCR and immunohistochemistry analysis, we found that CPTP is highly expressed in PC and is associated with a poor prognosis in PC patients. By using cell counting kit-8, colony formation, transwell and matrigel assays in vitro, as well as xenograft model assays in vivo, we further proved that CPTP enhanced PC cells growth and metastasis. In PC cells, human CPTP promotes growth and metastasis via sphingolipid metabolite ceramide and PI4KA/AKT signaling. Sp (specific protein)-1 and Sp3 transcription factors also act as upstream positive regulators of CPTP expression in PC cells. Collectively, these findings suggested that CPTP may function as a pro-tumorigenic gene in PC cells and could be a promising therapeutic target in PC.

Glycolipid transfer protein is the prototypical and founding member of the new GLTP superfamily distinguished by a novel conformational fold and glycolipid binding motif. The present investigation provides the first insights into the organization, transcriptional status, phylogenetic/evolutionary relationships of GLTP genes.

Mechanical loading is an essential factor for bone formation. A previous study indicated that mechanical tensile strain of 2500 microstrain (με) at 0.5 Hz for 8 h promoted osteogenesis and corresponding mechanoresponsive microRNAs (miRs) were identified in osteoblasts. However, in osteocytes, it has not been identified which miRs respond to the mechanical strain, and it is not fully understood how the mechanoresponsive miRs regulate osteoblast differentiation.

Human cathelicidin antimicrobial peptide and its active product, LL‑37 (CAMP/LL‑37), exhibit a broad spectrum of antimicrobial effects. An increasing number of studies have shown that human CAMP/LL‑37 also serves significant roles in various types of cancer. The primary aims of the present study were to investigate the roles and mechanisms of human CAMP/LL‑37 in oral squamous cell carcinoma (OSCC) cells. The results indicated that either LL‑37 C‑terminal deletion mutants (CDEL) or CAMP stable expression in HSC‑3 cells reduced colony formation, proliferation, migration and invasion ability of the cells. Expression analysis demonstrated that either CDEL or CAMP stable expression in HSC‑3 cells induced caspase‑3 mediated apoptosis via the P53‑Bcl‑2/BAX signalling pathway, whereas the levels of cell cycle‑related proteins, cyclin B1 and PKR‑like ER kinase, were significantly upregulated in the CAMP, but not in the CDEL overexpressing cells. Transcriptional profile comparisons revealed that CDEL or CAMP stable expression in HSC‑3 cells upregulated expression of genes involved in the IL‑17‑dependent pathway compared with the control. Taken together, these results suggest that CAMP may act as a tumour suppressor in OSCC cells, and the underlying mechanism involves the induction of caspase‑3 mediated apoptosis via the P53‑Bcl‑2/BAX signalling pathway.

Glycolipid transfer protein (GLTP) accelerates glycosphingolipid (GSL) intermembrane transfer via a unique lipid transfer/binding fold (GLTP-fold) that defines the GLTP superfamily and is the prototype for GLTP-like domains in larger proteins, i.e. phosphoinositol 4-phosphate adaptor protein-2 (FAPP2). Although GLTP-folds are known to play roles in the nonvesicular intracellular trafficking of glycolipids, their ability to alter cell phenotype remains unexplored. In the present study, overexpression of human glycolipid transfer protein (GLTP) was found to dramatically alter cell phenotype, with cells becoming round between 24 and 48 h after transfection. By 48 h post transfection, ∼70% conversion to the markedly round shape was evident in HeLa and HEK-293 cells, but not in A549 cells. In contrast, overexpression of W96A-GLTP, a liganding-site point mutant with abrogated ability to transfer glycolipid, did not alter cell shape. The round adherent cells exhibited diminished motility in wound healing assays and an inability to endocytose cholera toxin but remained viable and showed little increase in apoptosis as assessed by poly(ADP-ribose) polymerase cleavage. A round cell phenotype also was induced by overexpression of FAPP2, which binds/transfers glycolipid via its C-terminal GLTP-like fold, but not by a plant GLTP ortholog (ACD11), which is incapable of glycolipid binding/transfer. Screening for human protein partners of GLTP by yeast two hybrid screening and by immuno-pulldown analyses revealed regulation of the GLTP-induced cell rounding response by interaction with δ-catenin. Remarkably, while δ-catenin overexpression alone induced dendritic outgrowths, coexpression of GLTP along with δ-catenin accelerated transition to the rounded phenotype. The findings represent the first known phenotypic changes triggered by GLTP overexpression and regulated by direct interaction with a p120-catenin protein family member.

Phosphorylated sphingolipids ceramide-1-phosphate (C1P) and sphingosine-1-phosphate (S1P) have emerged as key regulators of cell growth, survival, migration and inflammation. C1P produced by ceramide kinase is an activator of group IVA cytosolic phospholipase A2α (cPLA2α), the rate-limiting releaser of arachidonic acid used for pro-inflammatory eicosanoid production, which contributes to disease pathogenesis in asthma or airway hyper-responsiveness, cancer, atherosclerosis and thrombosis. To modulate eicosanoid action and avoid the damaging effects of chronic inflammation, cells require efficient targeting, trafficking and presentation of C1P to specific cellular sites. Vesicular trafficking is likely but non-vesicular mechanisms for C1P sensing, transfer and presentation remain unexplored. Moreover, the molecular basis for selective recognition and binding among signalling lipids with phosphate headgroups, namely C1P, phosphatidic acid or their lyso-derivatives, remains unclear. Here, a ubiquitously expressed lipid transfer protein, human GLTPD1, named here CPTP, is shown to specifically transfer C1P between membranes. Crystal structures establish C1P binding through a novel surface-localized, phosphate headgroup recognition centre connected to an interior hydrophobic pocket that adaptively expands to ensheath differing-length lipid chains using a cleft-like gating mechanism. The two-layer, α-helically-dominated 'sandwich' topology identifies CPTP as the prototype for a new glycolipid transfer protein fold subfamily. CPTP resides in the cell cytosol but associates with the trans-Golgi network, nucleus and plasma membrane. RNA interference-induced CPTP depletion elevates C1P steady-state levels and alters Golgi cisternae stack morphology. The resulting C1P decrease in plasma membranes and increase in the Golgi complex stimulates cPLA2α release of arachidonic acid, triggering pro-inflammatory eicosanoid generation.

LL-37, the active product of human cathelicidin antimicrobial peptide (CAMP) has a broad spectrum of antibacterial activity. LL-37 also has important physiological functions in immune regulation, angiogenesis and in modulating apoptosis. The roles of LL-37 in oral squamous cell carcinoma (OSCC) are still not clear. The correlation between DNA methylation and human CAMP expression is also unknown. Here human CAMP/LL-37 expression was assessed by immunohistochemistry in normal and OSCC tissues. The results indicated that low expression of CAMP/LL-37 correlated with histological differentiation and lymph node metastasis and also promoted tumor progression. A cell-specific methylation pattern in the promoter region of human CAMP was detected. Treatment with 5-aza-2'-deoxycytidine, a DNA demethylation reagent can increase human CAMP expression in epithelial cancer cells. The reporter assay showed that unmethylated human CAMP promoter activity was significantly higher than methylated promoter activity. Taken together, these results suggested that human CAMP/LL-37 might act as a tumor-suppressor in OSCC and DNA methylation might play roles during carcinogenesis via directly downregulating human CAMP promoter activity.