Parathyroid Hormone-Related Protein Interacts With the Transforming Growth Factor-β/Bone Morphogenetic Protein-2/Gremlin Signaling Pathway to Regulate Proinflammatory and Profibrotic Mediators in Pancreatic Acinar and Stellate Cells

Acinar cells and the development of pancreatic fibrosis

Pancreatic fibrosis is caused by excessive deposition of extracellular matrixes of collagen and fibronectin in the pancreatic tissue as a result of repeated injury often seen in patients with chronic pancreatic diseases. The most common causative conditions include inborn errors of metabolism, chemical toxicity and autoimmune disorders. Its pathophysiology is highly complex, including acinar cell injury, acinar stress response, duct dysfunction, pancreatic stellate cell activation, and persistent inflammatory response. However, the specific mechanism remains to be fully clarified. Although the current therapeutic strategies targeting pancreatic stellate cells show good efficacy in cell culture and animal models, they are not satisfactory in the clinic. Without effective intervention, pancreatic fibrosis can promote the transformation from pancreatitis to pancreatic cancer, one of the most lethal malignancies. In the normal pancreas, the acinar component accounts for 82% of the exocrine tissue. Abnormal acinar cells may activate pancreatic stellate cells directly as cellular source of fibrosis or indirectly via releasing various substances and initiate pancreatic fibrosis. A comprehensive understanding of the role of acinar cells in pancreatic fibrosis is critical for designing effective intervention strategies. In this review, we focus on the role of and mechanisms underlying pancreatic acinar injury in pancreatic fibrosis and their potential clinical significance.

What Lies behind Paraneoplastic Hypercalcemia Secondary to Well-Differentiated Neuroendocrine Neoplasms? A Systematic Review of the Literature

BACKGROUND

Neuroendocrine neoplasms (NEN) originate from neuroendocrine cells ubiquitously spread throughout the body. Hypercalcemia associated with cancer is the most common life-threatening metabolic disorder in patients with advanced stage cancer. Paraneoplastic hypercalcemia is more commonly associated with hematological malignancies, renal and breast carcinomas, and squamous cell carcinomas, but it has also been described in patients with well-differentiated NEN, where it often remains undiagnosed. Among its causes, systemic secretion of parathyroid hormone-related protein (PTHrP) and ectopic production of 1,25-dihydroxyvitamin D and parathyroid hormone (PTH) may be considered paraneoplastic causes of hypercalcemia. In order to clarify the diagnostic work up of paraneoplastic hypercalcemia in patients with NEN, we perform a systematic review, which is lacking in the literature.

METHODS

We performed a data search using MEDLINE and SCOPUS including papers from 1961 to 2021. We selected articles on paraneoplastic hypercalcemia associated with well-differentiated NEN.

RESULTS

The search led to the selection of 78 publications for a total of 114 patients. Pooled data showed that the most frequent primary tumor site associated with paraneoplastic hypercalcemia was pancreatic NEN, followed by Pheochromocytoma. In most cases, paraneoplastic hypercalcemia was caused by PTHrP production and secretion. In more than two thirds of cases, paraneoplastic hypercalcemia was present at the time of NEN diagnosis and, in metachronous cases, was related to local recurrence, distant metastasis development, or tumor progression. In most patients, a combination of therapeutic approaches was employed, and reduction of the tumor burden was essential to control the paraneoplastic syndrome.

DISCUSSION

The onset of hypercalcemia associated with cancer in patients with well-differentiated NEN represents a major clinical challenge. The complex clinical and therapeutical management of paraneoplastic hypercalcemia implies the need for a multidisciplinary approach, aimed at controlling the clinical syndrome and tumor growth.

Uncarboxylated osteocalcin promotes proliferation and metastasis of MDA-MB-231 cells through TGF-β/SMAD3 signaling pathway

BACKGROUND

Triple-negative breast cancer (TNBC) is the most severe type of breast cancer owing to its high heterogeneity, aggressiveness and lack of treatment. Studies have reported that uncarboxylated osteocalcin (GluOC) promotes the development of prostate and other cancers. Studies have also found elevated levels of serum osteocalcin in breast cancer patients with bone metastasis, and serum osteocalcin can be a marker of bone metastasis. However, whether GluOC promotes the development of TNBC and the related mechanisms need to be further clarified.

RESULTS

Our results revealed that GluOC is associated with the proliferation and metastasis of MDA-MB-231 cells. GluOC increased the viability and proliferation of MDA-MB-231 cells. In addition, GluOC enhanced the metastatic ability of MDA-MB-231 cells by promoting the expression of matrix metalloproteinase-2 (MMP2), matrix metalloproteinase-13 (MMP13), and vascular endothelial growth factor (VEGF) and inducing epithelial-mesenchymal transition (EMT). We also found that GluOC upregulated the expression of interleukin-8 (IL-8) and parathyroid hormone-related protein (PTHrP) genes in MDA-MB-231 breast cancer cells. Moreover, the promoting effect of GluOC was reversed in MDA-MB-231 breast cancer cells treated with specific inhibitor of SMAD3 (SIS3), a SMAD3 phosphorylation inhibitor.

CONCLUSION

Our research proved for the first time that GluOC facilitates the proliferation and metastasis of MDA-MB-231 cells by accelerating the transforming growth factor-β (TGF-β)/SMAD3 signaling pathway. Moreover, GluOC also promotes the gene expression of IL-8 and PTHrP. Both IL-8 and PTHrP can act as osteolytic factors in breast cancer cells. This study indicates that GluOC may be a useful target for preventing TNBC bone metastasis.

Significance of cancer stroma for bone destruction in oral squamous cell carcinoma using different cancer stroma subtypes

Stromal cells in the tumor microenvironment (TME) can regulate the progression of numerous types of cancer; however, the bone invasion of oral squamous cell carcinoma (OSCC) has been poorly investigated. In the present study, the effect of verrucous SCC-associated stromal cells (VSCC-SCs), SCC-associated stromal cells (SCC-SCs) and human dermal fibroblasts on bone resorption and the activation of HSC-3 osteoclasts in vivo were examined by hematoxylin and eosin, AE1/3 (pan-cytokeratin) and tartrate-resistant acid phosphatase staining. In addition, the expression levels of matrix metalloproteinase (MMP)9, membrane-type 1 MMP (MT1-MMP), Snail, receptor activator of NF-κB ligand (RANKL) and parathyroid hormone-related peptide (PTHrP) in the bone invasion regions of HSC-3 cells were examined by immunohistochemistry. The results suggested that both SCC-SCs and VSCC-SCs promoted bone resorption, the activation of osteoclasts, and the expression levels of MMP9, MT1-MMP, Snail, RANKL and PTHrP. However, SCC-SCs had a more prominent effect compared with VSCC-SCs. Finally, microarray data were used to predict potential genes underlying the differential effects of VSCC-SCs and SCC-SCs on bone invasion in OSCC. The results revealed that IL1B, ICAM1, FOS, CXCL12, INS and NGF may underlie these differential effects. In conclusion, both VSCC-SCs and SCC-SCs may promote bone invasion in OSCC by enhancing the expression levels of RANKL in cancer and stromal cells mediated by PTHrP; however, SCC-SCs had a more prominent effect. These findings may represent a potential regulatory mechanism underlying the bone invasion of OSCC.

How neuroactive factors mediates immune responses during pregnancy: An interdisciplinary view

Pregnancy, from insemination to parturition, is a highly complex but well-orchestrated process that requires various organs and systems to participate. Immune system and neuroendocrine system are important regulators in healthy pregnancy. Dozens of neuroactive factors have been detected in human placenta, whether they are locally secreted or circulated. Among them, some are vividly studied such as corticotropin-releasing hormone (CRH), human chorionic gonadotropin (hCG), transforming growth factor-β (TGF-β), progesterone and estrogens, while others are relatively lack of research. Though the neuroendocrine-immune interactions are demonstrated in some diseases for decades, the roles of neuroactive factors in immune system and lymphocytes during pregnancy are not fully elucidated. This review aims to provide an interdisciplinary view on how the neuroendocrine system mediate immune system during pregnancy process.

Gremlin1 and TGF-β1 protect kidney tubular epithelial cells from ischemia-reperfusion injury through different pathways

BACKGROUND

Gremlin1 belongs to the superfamily members of transforming growth factor (TGF)-β1, playing a profibrotic role in chronic kidney diseases (CKD) and the transition from the late stage of acute kidney injury (AKI) to CKD, but the effect it plays in the early stage of AKI is unclear. This study aimed to investigate the role of Gremlin1on apoptosis in renal tubular epithelial cells under ischemia-reperfusion (I/R) induction.

METHODS

We detected Gremlin1 and TGF-β1 expression in the kidneys of mice undergoing renal ischemia-reperfusion injury bilaterally. We induced apoptosis through depletion and reperfusion of oxygen and serum in human kidney tubular epithelial cells (HKCs), mimicking I/R injury in vivo, and detected the role and pathways of Gremlin1 and TGF-β1on HKCs injury.

RESULTS

Mice undergoing bilateral I/R surgery presented AKI with a significant increase in serum creatinine, obvious renal tubular injuries, and increased macrophage cell and T-cell infiltration in interstitial areas. Gremlin1 expression was significantly increased along with TGF-β1 in the kidneys of AKI mice compared to sham mice. Exogenous Gremlin1 inhibited I/R-induced caspase3 expression in HKCs, which was blocked by a VEGFR2 kinase inhibitor III (SU5416). TGF-β1 also inhibited I/R-induced cell apoptosis in HKCs but had no synergic effect with Gremlin1. The TGF-β1's inhibitory effect could be blocked by the TGF-β1 type I receptor (activin receptor-like kinase 5, and ALK5)-specific inhibitor SB431542.

CONCLUSIONS

Gremlin1 and TGF- β1 protect kidney tubular epithelial cells from ischemia-reperfusion-induced apoptosis through VEGFR2 and Smad2 signaling pathways.

Down-regulation of Gremlin1 inhibits inflammatory response and vascular permeability in chronic idiopathic urticaria through suppression of TGF-β signaling pathway

Chronic idiopathic urticaria (CIU) is an unfavorable skin condition which could be maintained for six weeks or longer time. Gremlin1 (GREM1) was recently applied in treatments of many diseases. However, the possible regulatory mechanism of GREM1 in CIU remained unclear. This study aimed to explore the regulatory effects of GREM1 on the inflammatory response and vascular permeability mediated by mast cells of CIU via TGF-β signaling pathway. Initially, microarray analysis was used to identify CIU-related differentially expressed genes and the potential mechanism of this gene. A mouse model of CIU was established. To explore the functional role of GREM1 in CIU, the modeled mice were then injected with GREM1-siRNA, SRI-011381 (the activator of TGF-β signaling pathway), or both, followed by serum test, and immunoglobulin detection. The levels of inflammatory factors and tryptase, β-hexosaminase, histamine in the serum were detected. Besides, vascular endothelial cell permeability and the target relation between GREM1 and TGF-β were also examined. Mice injected with SRI-011381 exhibited higher levels of tryptase, β-hexosaminase, histamine, inflammation-related factors and increased vascular endothelial cell permeability, while GREM1-silenced mice yet expressed opposite tendency. Silencing of GREM1 was demonstrated to inhibit the TGF-β signaling pathway. Taken together, our results demonstrated that down-regulation of GREM1 could potentially impede inflammatory response and vascular permeability by suppressing TGF-β signaling pathway. GREM1 may promote the development of prognosis management and therapeutic treatment in CIU.

Inhibition of Rb phosphorylation leads to H2S-mediated inhibition of NF-kB in acute pancreatitis and associated lung injury in mice

BACKGROUND

Acute pancreatitis (AP), an inflammatory condition of pancreas, destructs the exocrine cells by releasing various pro-inflammatory cytokines that activates the stellate cells. However, the underlying molecular mechanism remains unclear. The present study investigated the role of retinoblastoma (Rb), hydrogen sulphide and nuclear factor-κB (NF-κB) in the regulation of exocrine cell proliferation under inflammatory condition.

METHODS

The randomly grouped male swiss mice were administered with 6 consecutive hourly i.p injections of caerulein to induce AP. Palbociclib (PD) (25 mg/kg body weight), a CDK4/6 inhibitor, was administered 1 h after the first cerulein injection intraperitoneally to block the RB pathway by inhibiting the activity of the CDK4/6 complexes and DL propargylglycine (PAG) which blocks the endogenous H₂S production.

RESULTS

Pharmacological inhibition of CDK4/6 and H₂S significantly improved pancreas and lung histopathological changes, decreased serum amylase level, both lung and pancreas myeloperoxidase (MPO) activity, TNFα expression and elevated IL10 expression. Furthermore, inhibition of RB pathway reduced cerulein-induced H₂S level by reducing the expression of cystathionine gamma lyase (CSE) and NF-κB activation in pancreas and lungs. Also, blocking the RB signalling reduced the α-SMA expression in pancreas preventing the risk for pancreatic fibrosis. Whereas administration of H₂S inhibitor PAG resulted in a decrease in CDK4/6-Rb expression in cerulein-induced AP.

CONCLUSION

These results reveal a novel link between H₂S/RB/NF-κB pathways, in AP and provide insight into possible mechanism that can be targeted in prevention of inflammation to cancer development.

Physiological roles of parathyroid hormone-related protein

Background: Parathyroid hormone related peptide (PTHrP) is widely expressed in a variety of normal fetal and adult tissues. Aim of work: Review of these normal physiologic functions of PTHrP in each of these tissues. Method: Performed literature search on pubmed on articles related to PTHrP and physiologic roles. Results: PTHrP is expressed in wide range of sites in the body with roles including relaxation of vessels and smooth muscle cells, and regulation of development. PTHrP also mediates humoral hypercalcemia of malignancy. PTHrP can be falsely elevated in benign conditions. Lastly, PTHrP has a pharmacological role in osteoporosis treatment. Conclusions: PTHrP has many various physiological roles besides mediating humoral hypercalcemia of malignancy. (www.actabiomedica.it)

Apigenin Decreases Acinar Cell Damage in Pancreatitis

OBJECTIVE

Chronic pancreatitis is the consequence of multiple episodes of recurrent acute pancreatitis (RAP). We hypothesized that apigenin can minimize the sequelae of RAP by limiting acinar cells' proinflammatory signaling pathways.

METHODS

AR42J acinar cells were treated in vitro with transforming growth factor β (TGF-β), apigenin, and other inhibitors. Dual luciferase reporter assay measured parathyroid hormone-related protein (PTHrP) promoter activity. MAPK/ERK pathway activity was assessed by immunoblotting and in vivo by immunohistochemistry with a cerulein-induced RAP mouse model. Nuclear factor κ B nuclear localization was analyzed in vitro in cells stimulated with tumor necrosis factor α. Primary acini were isolated and treated with cerulein; interleukin 6 messenger RNA was measured comparing PTHrP wild-type and knockout mice.

RESULTS

Apigenin and PD98059 each downregulated TGF-β stimulation of PTHrP P3 promoter activity. In a RAP mouse model, apigenin reduced pERK nuclear localization in acinar cells and preserved acinar cell architecture. Apigenin suppressed tumor necrosis factor α-mediated signaling by decreasing nuclear factor κ B nuclear localization and decreased interleukin 6 messenger RNA levels via a PTHrP-dependent mechanism.

CONCLUSIONS

Apigenin reduced inflammatory responses in experimental models of RAP. The mechanisms mediating the actions of apigenin, in part, are owing to attenuation of PTHrP and TGF-β proinflammatory signaling.

Parathyroid Hormone-Like Hormone Induces Epithelial-to-Mesenchymal Transition of Intestinal Epithelial Cells by Activating the Runt-Related Transcription Factor 2

Epithelial-to-mesenchymal transition (EMT) is a key contributor to fibroblast activation in fibrosis of multiple organs, including the intestine. Parathyroid hormone-like hormone (PTHLH) is an important factor in renal fibrosis and regulates several processes, including EMT. Herein, we investigated the role of PTHLH-induced EMT in intestinal fibrosis associated with Crohn disease. The expression levels of the EMT-related proteins, PTHLH, and parathyroid hormone receptor 1 (PTH1R) in intestinal tissues were determined by immunohistochemistry, and our results revealed that PTHLH and PTH1R were significantly elevated and associated with EMT marker expression. Moreover, neutralizing PTH1R and antagonizing PTHLH bioactivity prevented transforming growth factor-β1-induced EMT. PTH1R can propagate the protein kinase A (PKA) signal and activate downstream nuclear transcription factors, including runt-related transcription factor 2 (Runx2). In addition, lentiviral vector-PTHLH-treated mice were highly sensitive to 2,4,6-trinitrobenzene sulfonic acid, and analysis of the PTHLH-PTH1R axis revealed the involvement of PKA-Runx2 in PTHLH-induced EMT. Our results indicate that PTHLH triggered EMT in intestinal epithelial cells through the PKA-Runx2 pathway, which might serve as a therapeutic target for intestinal fibrosis in Crohn disease.

SMAD3/Stat3 Signaling Mediates β-Cell Epithelial-Mesenchymal Transition in Chronic Pancreatitis-Related Diabetes

Many patients with chronic pancreatitis develop diabetes (chronic pancreatitis-related diabetes [CPRD]) through an undetermined mechanism. Here we used long-term partial pancreatic duct ligation (PDL) as a model to study CPRD. We found that long-term PDL induced significant β-cell dedifferentiation, followed by a time-dependent decrease in functional β-cell mass-all specifically in the ligated tail portion of the pancreas (PDL-tail). High levels of transforming growth factor β1 (TGFβ1) were detected in the PDL-tail and were mainly produced by M2 macrophages at the early stage and by activated myofibroblasts at the later stage. Loss of β-cell mass was then found to result from TGFβ1-triggered epithelial-mesenchymal transition (EMT) by β-cells, rather than resulting directly from β-cell apoptosis. Mechanistically, TGFβ1-treated β-cells activated expression of the EMT regulator gene Snail in a SMAD3/Stat3-dependent manner. Moreover, forced expression of forkhead box protein O1 (FoxO1), an antagonist for activated Stat3, specifically in β-cells ameliorated β-cell EMT and β-cell loss and prevented the onset of diabetes in mice undergoing PDL. Together, our data suggest that chronic pancreatitis may trigger TGFβ1-mediated β-cell EMT to lead to CPRD, which could substantially be prevented by sustained expression of FoxO1 in β-cells.

Pancreatic stellate cells: what's new?

PURPOSE OF REVIEW

Pancreatic stellate cells (PSCs) play an integral role in the pathogenesis of pancreatitis and pancreatic cancer. With the developing knowledge of this important cell type, we are at the cusp of developing effective therapies for the above diseases based upon targeting the PSC and modulating its function.

RECENT FINDINGS

The major themes of the recent PSC literature include: PSC interactions with the extracellular matrix and other stromal components; intracellular calcium physiology as drivers of mechanical interactions and necrosis; the relationship between proinflammatory, protumoural, angiogenic, and metabolic pathways in pancreatic necrosis, fibrosis, and carcinogenesis; and targeting of the stroma for antitumoural and antifibrotic effects.

SUMMARY

Traditionally, there have been few treatment options for pancreatitis and pancreatic cancer. The elucidation of the wide-ranging functions of PSCs provide an opportunity for treatments based on stromal reprogramming.