Po-Chun Chen

Arsenic induces cell apoptosis in cultured osteoblasts through endoplasmic reticulum stress.

Osteoporosis is characterized by low bone mass resulting from an imbalance between bone resorption by osteoclasts and bone formation by osteoblasts. Therefore, decreased bone formation by osteoblasts may lead to the development of osteoporosis, and rate of apoptosis is responsible for the regulation of bone formation. Arsenic (As) exists ubiquitously in our environment and increases the risk of neurotoxicity, liver injury, peripheral vascular disease and cancer. However, the effect of As on apoptosis of osteoblasts is mostly unknown. Here, we found that As induced cell apoptosis in osteoblastic cell lines (including hFOB, MC3T3-E1 and MG-63) and mouse bone marrow stromal cells (M2-10B4). As also induced upregulation of Bax and Bak, downregulation of Bcl-2 and dysfunction of mitochondria in osteoblasts. As also triggered endoplasmic reticulum (ER) stress, as indicated by changes in cytosolic-calcium levels. We found that As increased the expression and activities of glucose-regulated protein 78 (GRP78) and calpain. Transfection of cells with GRP78 or calpain siRNA reduced As-mediated cell apoptosis in osteoblasts. Therefore, our results suggest that As increased cell apoptosis in cultured osteoblasts and increased the risk of osteoporosis.

The CCN family proteins: modulators of bone development and novel targets in bone-associated tumors.

The CCN family of proteins is composed of six extracellular matrix-associated proteins that play crucial roles in skeletal development, wound healing, fibrosis, and cancer. Members of the CCN family share four conserved cysteine-rich modular domains that trigger signal transduction in cell adhesion, migration, proliferation, differentiation, and survival through direct binding to specific integrin receptors and heparan sulfate proteoglycans. In the present review, we discuss the roles of the CCN family proteins in regulating resident cells of the bone microenvironment. In vertebrate development, the CCN family plays a critical role in osteo/chondrogenesis and vasculo/angiogenesis. These effects are regulated through signaling via integrins, bone morphogenetic protein, vascular endothelial growth factor, Wnt, and Notch via direct binding to CCN family proteins. Due to the important roles of CCN family proteins in skeletal development, abnormal expression of CCN proteins is related to the tumorigenesis of primary bone tumors such as osteosarcoma, Ewing sarcoma, and chondrosarcoma. Additionally, emerging studies have suggested that CCN proteins may affect progression of secondary metastatic bone tumors by moderating the bone microenvironment. CCN proteins could therefore serve as potential therapeutic targets for drug development against primary and metastatic bone tumors.

CCN3 increases cell motility and ICAM-1 expression in prostate cancer cells

Nephroblastoma overexpressed (NOV or CCN3) is a secreted matrix-associated protein that belongs to the CCN gene family and is involved in many cellular functions, including growth, differentiation and adhesion. The effect of CCN3 on human prostate cancer cells, however, is unknown. Here, we have shown that CCN3 increased cell migration and intercellular adhesion molecule-1 (ICAM-1) expression in prostate cancer cells. In addition, expression of CCN3 was positively correlated with both cell migration and ICAM-1 expression in human prostate cancer cells. CCN3 activated a signal transduction pathway that included αvβ3 integrin, integrin-linked kinase (ILK), Akt and nuclear factor-kappaB (NF-κB). Reagents that inhibit specific components of this pathway each diminished the ability of CCN3 to effect cell migration and ICAM-1 expression. Moreover, CCN3 increased binding of p65 to an NF-κB-binding element in the ICAM-1 promoter. Finally, knockdown of CCN3 expression markedly inhibited cell migration, tumor growth in bone and bone metastasis. Taken together, our results indicate that CCN3 enhances the migration of prostate cancer cells by increasing ICAM-1 expression through a signal transduction pathway that involves αvβ3 integrin, ILK, Akt and NF-κB. CCN3 thus represents a promising new target for treating prostate cancer.

CCN3 promotes prostate cancer bone metastasis by modulating the tumor–bone microenvironment through RANKL-dependent pathway

Bone metastasis in patient with advanced-stage prostate cancer, the most commonly diagnosed malignancy in Western countries, increases the risk of intractable bone pain. The nephroblastoma overexpressed (NOV/CCN3) gene, a member of the CCN gene family, is responsible for the secretion of CCN3, a matrix-associated protein involved in many cellular functions. However, the role of CCN3 in prostate cancer metastasis to bone is poorly understood. CCN3 was found to be highly expressed in bone metastasis patients and positively correlated with malignancy in human prostate cancer cells. Prostate cancer conditioned medium-induced osteoclast differentiation was inhibited by neutralizing antibody against CCN3. Specifically, CCN3 was found to induce osteoclastogenesis through the receptor activator of NF-κB ligand (RANKL)-dependent pathway, and the focal adhesion kinase/Akt/p38/NF-κB signal pathway was found to be involved in CCN3-mediated receptor activator of NF-κB expression and RANKL-dependent osteoclastogenesis. In contrast, osteoblasts were observed to play an important role in osteoclast differentiation by paracrine manner, with treatment of osteoblasts with CCN3 found to change the RANKL (osteoclastogenesis):OPG (antiosteoclastogenesis) ratio. Compared with parental PC3 cells, highly invasive PC3-I3 cells markedly enhanced osteoclast activity and bone metastasis in vivo. These results indicate that CCN3 can be used as a novel therapeutic target in the prevention of bone metastasis of prostate cancer.

WISP-1 promotes VEGF-C-dependent lymphangiogenesis by inhibiting miR-300 in human oral squamous cell carcinoma cells

Oral squamous cell carcinoma (OSCC), which accounts for nearly 90% of head and neck cancers, is characterized by a poor prognosis and a low survival rate. Vascular endothelial growth factor-C (VEGF-C) has been implicated in lymphangiogenesis and is correlated with cancer metastasis. WNT1-inducible signaling pathway protein-1 (WISP)-1/CCN4 is an extracellular matrix-related protein that belongs to the CCN family and stimulates many biological functions. Our previous studies showed that WISP-1 plays an important role in OSCC migration and angiogenesis. However, the effect of WISP-1 on VEGF-C regulation and lymphangiogenesis in OSCC is poorly understood. Here, we showed a correlation between WISP-1 and VEGF-C in tissue specimens from patients with OSCC. To examine the lymphangiogenic effect of WISP-1, we used human lymphatic endothelial cells (LECs) to mimic lymphatic vessel formation. The results showed that conditioned media from WISP-1-treated OSCC cells promoted tube formation and cell migration in LECs. We also found that WISP-1-induced VEGF-C is mediated via the integrin αvβ3/integrin-linked kinase (ILK)/Akt signaling pathway. In addition, the expression of microRNA-300 (miR-300) was inhibited by WISP-1 via the integrin αvβ3/ILK/Akt cascade. Collectively, these results reveal the detailed mechanism by which WISP-1 promotes lymphangiogenesis via upregulation of VEGF-C expression in OSCC. Therefore, WISP-1 could serve as therapeutic target to prevent metastasis and lymphangiogenesis in OSCC.

Association of HMGB1 Gene Polymorphisms with Lung Cancer Susceptibility and Clinical Aspects

Lung cancer is one of the most frequently diagnosed malignancies and is associated with a poor survival rate in the Chinese Han population. Analysis of genetic variants could lead to improvements in prognosis following lung cancer therapy. High-mobility group box 1 protein (HMGB1) is a ubiquitous nuclear protein found in eukaryotic cells that participates in several biological functions including immune response, cell survival, apoptosis and cancer development. We investigated the effects of HMGB1 gene polymorphisms on the risk of lung cancer progression in a Chinese Han population. Our sample of 751 participants included 372 patients with lung cancer and 379 healthy controls. Four single-nucleotide polymorphisms (SNPs) of the HMGB1 gene were examined by real-time polymerase chain reaction (RT-PCR). We found that the CT or CC+CT heterozygotes of the HMGB1 rs1045411 polymorphism reduced the risks for lung cancer, while the G/T/C haplotypes of three HMGB1 SNPs (rs1360485, rs1045411 and rs2249825) also reduced the risk for lung cancer by almost half (0.486-fold). The current study is the first to examine the risk factors associated with HMGB1 SNPs in lung cancer development in the Chinese Han population.

Periostin promotes epithelial-mesenchymal transition via the MAPK/miR-381 axis in lung cancer

Periostin (POSTN, PN, or osteoblast-specific factor OSF-2) is a multifunctional cytokine that signals between the cell and the extracellular matrix. Periostin plays an important role in tumor development and is involved in carcinoma cell epithelial-mesenchymal transition (EMT), whereby mature epithelial cells undergo phenotypic morphological changes and become invasive, motile cells. Here, we discuss the molecular mechanisms involved in periostin-induced promotion of EMT in lung cancer cells. Online TCGA datasets demonstrate the prognostic relevance of periostin in lung cancer; a higher periostin level correlates with poor overall survival. Similarly, our IHC results show that high periostin expression is positively correlated with the EMT markers Snail and Twist, as well as stage of lung cancer. We found that recombinant periostin induces the EMT phenotype in lung cancer cells through the p38/ERK pathway, while pretreatment with chemical inhibitors prevented periostin-induced EMT induction. Moreover, we found that periostin regulates EMT by repressing microRNA-381 (miR-381) expression, which targets both Snail and Twist. Using the miR-381 mimic, we dramatically reversed periostin-induced Snail and Twist expression. Furthermore, periostin knockdown dramatically affected EMT markers and cell migration potential. The role of periostin in lung cancer progression is elucidated by the in vivo mouse model. Our findings indicate that changes in periostin expression in lung cancer may serve as a therapeutic target for the treatment of lung cancer metastasis.Periostin (POSTN, PN, or osteoblast-specific factor OSF-2) is a multifunctional cytokine that signals between the cell and the extracellular matrix. Periostin plays an important role in tumor development and is involved in carcinoma cell epithelial-mesenchymal transition (EMT), whereby mature epithelial cells undergo phenotypic morphological changes and become invasive, motile cells. Here, we discuss the molecular mechanisms involved in periostin-induced promotion of EMT in lung cancer cells. Online TCGA datasets demonstrate the prognostic relevance of periostin in lung cancer; a higher periostin level correlates with poor overall survival. Similarly, our IHC results show that high periostin expression is positively correlated with the EMT markers Snail and Twist, as well as stage of lung cancer. We found that recombinant periostin induces the EMT phenotype in lung cancer cells through the p38/ERK pathway, while pretreatment with chemical inhibitors prevented periostin-induced EMT induction. Moreover, we found that periostin regulates EMT by repressing microRNA-381 (miR-381) expression, which targets both Snail and Twist. Using the miR-381 mimic, we dramatically reversed periostin-induced Snail and Twist expression. Furthermore, periostin knockdown dramatically affected EMT markers and cell migration potential. The role of periostin in lung cancer progression is elucidated by the in vivo mouse model. Our findings indicate that changes in periostin expression in lung cancer may serve as a therapeutic target for the treatment of lung cancer metastasis.

Prognostic significance of high-mobility group box protein 1 genetic polymorphisms in rheumatoid arthritis disease outcome

Rheumatoid arthritis (RA) is a systemic inflammatory disease that causes chronic inflammation of the joints. Analysis of genetic variants offers promise for guiding treatment and improving outcomes in RA. High-mobility group box protein 1 (HMGB1) is a ubiquitous nuclear protein found in all mammal eukaryotic cells that participates in several biological functions including immune response, cell survival and apoptosis. We investigated the effects of HMGB1 gene polymorphisms on the risk of RA disease progression in a cohort of Chinese Han individuals. Four single nucleotide polymorphisms (SNPs) from the HMGB1 gene were selected and genotyped in 232 patients with RA and 353 healthy controls. We found that having one C allele in rs1360485 and one G allele in rs2249825 polymorphisms lowered the risk of RA in females. Moreover, among healthy controls, those who bore the C/G/T haplotype at SNPs rs1360485, rs2249825 and rs1412125 were at reduced risk of developing RA by 0.13-fold (p <0.05). This is the first report to examine the risk factors associated with HMGB1 SNPs in the development of RA disease in the Chinese Han population.

Correlation between CCL4 gene polymorphisms and clinical aspects of breast cancer

Breast cancer is a major cause of cancer mortality amongst women. Chemokine (C-C motif) ligand 4 is encoded by the CCL4 gene; specific CCL4 gene polymorphisms are related to the risks and prognoses of various diseases. In this study, we examined whether CCL4 gene single nucleotide polymorphisms (SNPs) predict the risk and progression of breast cancer. Between 2014 and 2016, we recruited 314 patients diagnosed with breast cancer and a cohort of 209 healthy participants (controls) without a history of cancer. Genotyping of the CCL4 rs1634507, rs10491121 and rs1719153 SNPs revealed no significant between-group differences for these polymorphisms. However, amongst luminal A and luminal B subtypes, compared with patients with the AA genotype, those carrying the AG genotype at SNP rs10491121 were less likely to develop lymph node metastasis. In addition, compared with AA carriers, those carrying the AG + GG genotype at SNP rs10491121 were at lower risk of developing distant metastasis, while the presence of the AT genotype at SNP rs1719153 increased the likelihood of pathologic grade (G3 or G4) disease. Variations in the CCL4 gene may help to predict breast cancer progression and metastasis.

Osteoblast-secreted WISP-1 promotes adherence of prostate cancer cells to bone via the VCAM-1/integrin α4β1 system

Bone metastasis is a frequent occurrence in prostate cancer (PCa) that is associated with severe complications such as fracture, bone pain and hypercalcemia. The cross-talk between metastatic cancer cells and bone is critical to the development and progression of bone metastases. In our previous data, we have described how the involvement of the Wnt-induced secreted protein-1/vascular cell adhesion molecule-1 (WISP-1/VCAM-1) system in this tumor-bone interaction contributes to human PCa cell motility. In this study, we found that WISP-1 regulates bone mineralization by inducing bone morphogenetic protein-2 (BMP2), BMP4 and osteopontin (OPN) expression in osteoblasts. We also found that WISP-1 inhibited RANKL-dependent osteoclastogenesis. Moreover, osteoblast-derived WISP-1 enhanced VCAM-1 expression in PCa cells and subsequently promoted the adherence of cancer cells to osteoblasts. Furthermore, endothelin-1 (ET-1) expression in PCa cells was regulated by osteoblast-derived WISP-1, which promoted integrin α4β1 expression in osteoblasts via the MAPK pathway. Pretreatment of PCa cells with VCAM-1 antibody or osteoblasts with integrin α4β1 antibody attenuated the adherence of PCa cells to osteoblasts, suggesting that integrin α4β1 serves as a ligand that captures VCAM-1+ metastatic tumor cells adhering to osteoblasts. Our findings reveal that osteoblast-derived WISP-1 plays a key role in regulating the adhesion of PCa cells to osteoblasts via the VCAM-1/integrin α4β1 system. Osteoblast-derived WISP-1 is a promising target for the prevention and inhibition of PCa-bone interaction.