Activation of the PI3K/Akt pathway mediates bone morphogenetic protein 2-induced invasion of pancreatic cancer cells Panc-1

Bone morphogenetic protein 2 rescues neurogenic abnormalities and angiogenic factors in mice with bilateral cavernous nerve injury

BACKGROUND

Bone morphogenetic protein 2 (BMP2), a key isoform within the bone morphogenetic protein family, plays a critical role in promoting angiogenesis and peripheral nerve regeneration, but its specific role in neurogenic erectile dysfunction (ED) remains unclear.

AIM

This study aimed to explore the therapeutic efficacy of exogenous recombinant BMP2 protein administration in restoring erectile function in a mouse model of cavernous nerve injury (CNI)-induced ED.

METHODS

Twelve-week-old male C57BL/6 mice were used to evaluate BMP2 expression and erectile function following CNI. Western blotting and immunofluorescence staining were employed to assess BMP2 levels in corpus cavernosum tissues from both sham-operated and CNI-induced ED mice. Erectile function was measured through electrical stimulation of bilateral cavernous nerves, with subsequent intracavernous pressure parameter recordings. Mechanistic investigations included immunofluorescence staining, terminal deoxynucleotidyl transferase dUTP nick-end labeling assay, and western blot analysis. Additionally, ex vivo neurite outgrowth assays were conducted using dorsal root ganglia (DRG) and major pelvic ganglia (MPG) tissues.

OUTCOMES

In vivo intracavernous pressure, neurovascular regeneration, proliferation, apoptosis, ex vivo neurite sprouting, and survival signaling were measured.

RESULTS

Bone morphogenetic protein 2 expression was significantly decreased in the corpus cavernosum of CNI mice. Exogenous administration of recombinant BMP2 protein effectively enhanced erectile function in CNI mice, likely through the restoration of endothelial cells, smooth muscle cells, pericytes, and neuronal cells within the corpus cavernosum. Immunofluorescence staining and western blot analysis demonstrated that BMP2 treatment promoted angiogenesis by increasing endothelial cell proliferation and reducing apoptosis in the corpus cavernosum. Furthermore, ex vivo assays revealed that BMP2 promoted neurite sprouting in DRG and MPG tissues exposed to lipopolysaccharide. Mechanistic studies further indicated that BMP2 increased the expression of neurotrophic factors and VEGF, activating the AKT/eNOS signaling pathway.

CLINICAL IMPLICATIONS

Bone morphogenetic protein 2 may be used as a strategy to treat neurogenic ED or other neurovascular diseases.

STRENGTHS AND LIMITATIONS

Bone morphogenetic protein 2 has dual roles in vascular and neuronal development. Our study focused on broadly evaluating the role of BMP2 in neurogenic ED. Future studies will evaluate the nerve regeneration effects and novel signaling pathways of BMP2 in a sciatic nerve injury mouse model. In view of its properties as an angiogenic factor, its dose concentration should be strictly controlled to avoid potential side effects.

CONCLUSIONS

The exogenous administration of recombinant BMP2 protein significantly improved erectile function in CNI mice, suggesting BMP2 as a promising therapeutic candidate for neurogenic ED.

Non-small cell lung cancer map and analysis: exploring interconnected oncogenic signal integrators

Non-Small Cell lung cancer (NSCLC) is known for its fast progression, metastatic potency, and a leading cause of mortality globally. At diagnosis, approximately 30-40% of NSCLC patients already present with metastasis. Epithelial to mesenchymal transition (EMT) is a developmental program implicated in cancer progression and metastasis. Transforming Growth Factor-β (TGFβ) and its signalling plays a prominent role in orchestrating the process of EMT and cancer metastasis. In present study, a comprehensive molecular interaction map of TGFβ induced EMT in NSCLC was developed through an extensive literature survey. The map encompasses 394 species interconnected through 554 reactions, representing the relationship and complex interplay between TGFβ induced SMAD dependent and independent signalling pathways (PI3K/Akt, Wnt, EGFR, JAK/STAT, p38 MAPK, NOTCH, Hypoxia). The map, built using Cell Designer and compliant with SBGN and SBML standards, was subsequently translated into a logical modelling framework using CaSQ and dynamically analysed with Cell Collective. These analyses illustrated the complex regulatory dynamics, capturing the known experimental outcomes of TGFβ induced EMT in NSCLC including the co-existence of hybrid EM phenotype during transition. Hybrid EM phenotype is known to contribute for the phenotypic plasticity during metastasis. Network-based analysis identified the crucial network level properties and hub regulators, while the transcriptome-based analysis cross validated the prognostic significance and clinical relevance of key regulators. Overall, the map developed and the subsequent analyses offer deeper understanding of the complex regulatory network governing the process of EMT in NSCLC.

Bone morphogenetic protein inhibitors and mitochondria targeting agents synergistically induce apoptosis-inducing factor (AIF) caspase-independent cell death in lung cancer cells

BACKGROUND

Bone morphogenetic proteins (BMP) are evolutionarily conserved morphogens that are reactivated in lung carcinomas. In lung cancer cells, BMP signaling suppresses AMP activated kinase (AMPK) by inhibiting LKB1. AMPK is activated by mitochondrial stress that inhibits ATP production, which is enhanced 100-fold when phosphorylated by LKB1. Activated AMPK can promote survival of cancer cells but its "hyperactivation" induces cell death. The studies here reveal novel cell death mechanisms induced by BMP inhibitors, together with agents targeting the mitochondria, which involves the "hyperactivation" of AMPK.

METHODS

This study examines the synergistic effects of two BMP inhibitors together with mitochondrial targeting agents phenformin and Ym155, on cell death of lung cancer cells expressing LKB1 (H1299), LKB1 null (A549), and A549 cells transfected with LKB1 (A549-LKB1). Cell death mechanisms evaluated were the activation of caspases and the nuclear localization of apoptosis inducing factor (AIF). A769662 was used to allosterically activate AMPK. Knockdown of BMPR2 and LKB1 using siRNA was used to examine their effects on nuclear localization of AMPK. Validation studies were performed on five passage zero primary NSCLC.

RESULTS

Both BMP inhibitors synergistically suppressed growth when combined with Ym155 or phenformin in cells expressing LKB1. The combination of BMP inhibitors with mitochondrial targeting agents enhanced the activation of AMPK in lung cancer cells expressing LKB1. Allosteric activation of AMPK with A769662 induced cell death in both H1299 and A549 cells. Cell death induced by the combination of BMP inhibitors and mitochondrial-targeting agents did not activate caspases. The combination of drugs induced nuclear localization of AIF in cells expressing LKB1, which was attenuated by knockdown of LKB1. Knockdown of BMPR2 together with Ym155 increased nuclear localization of AIF. Combination therapy also enhanced cell death and AIF nuclear localization in primary NSCLC.

CONCLUSIONS

These studies demonstrate that inhibition of BMP signaling together with mitochondrial targeting agents induce AIF caspase-independent cell death, which involves the "hyperactivation" of AMPK. AIF caspase-independent cell death is an evolutionarily conserved cell death pathway that is infrequently studied in cancer. These studies provide novel insight into mechanisms inducing AIF caspase-independent cell death in cancer cells using BMP inhibitors. Video Abstract.

Bone morphogenetic protein signaling regulation of AMPK and PI3K in lung cancer cells and C. elegans

BACKGROUND

Bone morphogenetic protein (BMP) is a phylogenetically conserved signaling pathway required for development that is aberrantly expressed in several age-related diseases including cancer, Alzheimer's disease, obesity, and cardiovascular disease. Aberrant BMP signaling in mice leads to obesity, suggesting it may alter normal metabolism. The role of BMP signaling regulating cancer metabolism is not known.

METHODS

To examine BMP regulation of metabolism, C. elegans harboring BMP gain-of-function (gof) and loss-of-function (lof) mutations were examined for changes in activity of catabolic and anabolic metabolism utilizing Western blot analysis and fluorescent reporters. AMP activated kinase (AMPK) gof and lof mutants were used to examine AMPK regulation of BMP signaling. H1299 (LKB1 wild-type), A549 (LKB1 lof), and A549-LKB1 (LKB1 restored) lung cancer cell lines were used to study BMP regulation of catabolic and anabolic metabolism. Studies were done using recombinant BMP ligands to activate BMP signaling, and BMP receptor specific inhibitors and siRNA to inhibit signaling.

RESULTS

BMP signaling in both C. elegans and cancer cells is responsive to nutrient conditions. In both C. elegans and lung cancer cell lines BMP suppressed AMPK, the master regulator of catabolism, while activating PI3K, a regulator of anabolism. In lung cancer cells, inhibition of BMP signaling by siRNA or small molecules increased AMPK activity, and this increase was mediated by activation of LKB1. BMP2 ligand suppressed AMPK activation during starvation. BMP2 ligand decreased expression of TCA cycle intermediates and non-essential amino acids in H1299 cells. Furthermore, we show that BMP activation of PI3K is mediated through BMP type II receptor. We also observed feedback signaling, as AMPK suppressed BMP signaling, whereas PI3K increased BMP signaling.

CONCLUSION

These studies show that BMP signaling suppresses catabolic metabolism and stimulates anabolic metabolism. We identified feedback mechanisms where catabolic induced signaling mediated by AMPK negatively regulates BMP signaling, whereas anabolic signaling produces a positive feedback regulation of BMP signing through Akt. These mechanisms were conserved in both lung cancer cells and C. elegans. These studies suggest that aberrant BMP signaling causes dysregulation of metabolism that is a potential mechanism by which BMP promotes survival of cancer cells.

DNA Methylation Mediates EMT Gene Expression in Human Pancreatic Ductal Adenocarcinoma Cell Lines

Due to abundant stroma and extracellular matrix, accompanied by lack of vascularization, pancreatic ductal adenocarcinoma (PDAC) is characterized by severe hypoxia. Epigenetic regulation is likely one of the mechanisms driving hypoxia-induced epithelial-to-mesenchymal transition (EMT), responsible for PDAC aggressiveness and dismal prognosis. To verify the role of DNA methylation in this process, we assessed gene expression and DNA methylation changes in four PDAC cell lines. BxPC-3, MIA PaCa-2, PANC-1, and SU.86.86 cells were exposed to conditioned media containing cytokines and inflammatory molecules in normoxic and hypoxic (1% O2) conditions for 2 and 6 days. Cancer Inflammation and Immunity Crosstalk and Human Epithelial to Mesenchymal Transition RT² Profiler PCR Arrays were used to identify top deregulated inflammatory and EMT-related genes. Their mRNA expression and DNA methylation were quantified by qRT-PCR and pyrosequencing. BxPC-3 and SU.86.86 cell lines were the most sensitive to hypoxia and inflammation. Although the methylation of gene promoters correlated with gene expression negatively, it was not significantly influenced by experimental conditions. However, DNA methyltransferase inhibitor decitabine efficiently decreased DNA methylation up to 53% and reactivated all silenced genes. These results confirm the role of DNA methylation in EMT-related gene regulation and uncover possible new targets involved in PDAC progression.

Insights into Bone Morphogenetic Protein-(BMP-) Signaling in Ocular Lens Biology and Pathology

Bone morphogenetic proteins (BMPs) are a diverse class of growth factors that belong to the transforming growth factor-beta (TGFβ) superfamily. Although originally discovered to possess osteogenic properties, BMPs have since been identified as critical regulators of many biological processes, including cell-fate determination, cell proliferation, differentiation and morphogenesis, throughout the body. In the ocular lens, BMPs are important in orchestrating fundamental developmental processes such as induction of lens morphogenesis, and specialized differentiation of its fiber cells. Moreover, BMPs have been reported to facilitate regeneration of the lens, as well as abrogate pathological processes such as TGFβ-induced epithelial-mesenchymal transition (EMT) and apoptosis. In this review, we summarize recent insights in this topic and discuss the complexities of BMP-signaling including the role of individual BMP ligands, receptors, extracellular antagonists and cross-talk between canonical and non-canonical BMP-signaling cascades in the lens. By understanding the molecular mechanisms underlying BMP activity, we can advance their potential therapeutic role in cataract prevention and lens regeneration.

The BMP2 Signaling Axis Promotes Invasive Differentiation of Human Trophoblasts

Embryo implantation and trophoblast invasion are principal limiting factors of pregnancy establishment. Aberrant embryo development or improper trophoblast differentiation and invasion may lead to various unfavorable pregnancy-related outcomes, including early pregnancy loss (EPL). Our clinical data show that the serum BMP2 levels were significantly increased during the first trimester of pregnancy and that the serum and BMP2 expression levels were lower in women with EPL than in women with normal early pregnancies. Moreover, we observed that BMP2 was expressed in oocytes and trophoblast cells of cleaved embryos and blastocysts prior to implantation in both humans and mice. Exogenous BMP2 promoted embryonic development by enhancing blastocyst formation and hatching in mice. LncRNA NR026833.1 was upregulated by BMP2 and promoted SNAIL expression by competitively binding to miR-502-5p. SNAIL induced MMP2 expression and promoted cell invasion in primary extravillous trophoblast cells. BMP2 promotes the invasive differentiation of mouse trophoblast stem cells by downregulating the expression of TS cell marker and upregulating the expression of trophoblast giant cell marker and labyrinthine/spongiotrophoblast marker. Our findings provide significant insights into the regulatory roles of BMP2 in the development of the placenta, which may give us a framework to explore new therapeutic strategies to pregnancy-related complications.

Secreted BMP antagonists and their role in cancer and bone metastases

Bone morphogenetic proteins (BMPs) are multifunctional secreted cytokines that act in a highly context-dependent manner. BMP action extends beyond the induction of cartilage and bone formation, to encompass pivotal roles in controlling tissue and organ homeostasis during development and adulthood. BMPs signal via plasma membrane type I and type II serine/threonine kinase receptors and intracellular SMAD transcriptional effectors. Exquisite temporospatial control of BMP/SMAD signalling and crosstalk with other cellular cues is achieved by a series of positive and negative regulators at each step in the BMP/SMAD pathway. The interaction of BMP ligand with its receptors is carefully controlled by a diverse set of secreted antagonists that bind BMPs and block their interaction with their cognate BMP receptors. Perturbations in this BMP/BMP antagonist balance are implicated in a range of developmental disorders and diseases, including cancer. Here, we provide an overview of the structure and function of secreted BMP antagonists, and summarize recent novel insights into their role in cancer progression and bone metastasis. Gremlin1 (GREM1) is a highly studied BMP antagonist, and we will focus on this molecule in particular and its role in cancer. The therapeutic potential of pharmacological inhibitors for secreted BMP antagonists for cancer and other human diseases will also be discussed.

Increased Expression of Gremlin1 Promotes Proliferation and Epithelial Mesenchymal Transition in Gastric Cancer Cells and Correlates With Poor Prognosis of Patients With Gastric Cancer

BACKGROUND/AIM

Gremlin1 (GREM1) plays an important role in certain malignancies by antagonising bone morphogenetic proteins and regulating angiogenesis directly/indirectly. The present study aimed to investigate the role of Gremlin1 in the development and progression of gastric cancer (GC).

MATERIALS AND METHODS

Expression of GREM1 in GCs was examined using quantitative real time PCR and The Cancer Genomic Atlas (TCGA) data. Influence on cellular functions was determined in both Gremlin1 knockdown and overexpression cell line models.

RESULTS

GREM1 expression was up-regulated in GCs, which was correlated with poorer survival. Increased GREM1 expression was significantly correlated with tumour growth/invasion and lymphatic metastasis. Gremlin1 promoted proliferation and tumourigenic capacity of GC cells in vitro. GREM1 expression was associated with epithelial mesenchymal transition (EMT), angiogenesis and lymphangiogenesis in GC.

CONCLUSION

Increased GREM1 expression in GCs is associated with disease progression and poor prognosis in which EMT, angiogenesis and lymphangiogenesis are likely involved.

Colorectal cancer (CRC) as a multifactorial disease and its causal correlations with multiple signaling pathways

Colorectal cancer (CRC) is the third most common malignancy and one of the leading causes of cancer-related death among men worldwide. CRC is a multifactor digestive pathology, which is a huge problem faced not only by clinicians but also by researchers. Importantly, a unique feature of CRC is the dysregulation of molecular signaling pathways. To date, a series of reviews have indicated that different signaling pathways are disordered and have potential as therapeutic targets in CRC. Nevertheless, an overview of the function and interaction of multiple signaling pathways in CRC is needed. Therefore, we summarized the pathways, biological functions and important interactions involved in CRC. First, we investigated the involvement of signaling pathways, including Wnt, PI3K/Akt, Hedgehog, ErbB, RHOA, Notch, BMP, Hippo, AMPK, NF-κB, MAPK and JNK. Subsequently, we discussed the biological function of these pathways in pathophysiological aspects of CRC, such as proliferation, apoptosis and metastasis. Finally, we summarized important interactions among these pathways in CRC. We believe that the interaction of these pathways could provide new strategies for the treatment of CRC.

Bone morphogenetic proteins mediate crosstalk between cancer cells and the tumour microenvironment at primary tumours and metastases (Review)

Bone morphogenetic proteins (BMP) are pluripotent molecules, co‑ordinating cellular functions from early embryonic and postnatal development to tissue repair, regeneration and homeostasis. They are also involved in tumourigenesis, disease progression and the metastasis of various solid tumours. Emerging evidence has indicated that BMPs are able to promote disease progression and metastasis by orchestrating communication between cancer cells and the surrounding microenvironment. The interactions occur between BMPs and epidermal growth factor receptor, hepatocyte growth factor, fibroblast growth factor, vascular endothelial growth factor and extracellular matrix components. Overall, these interactions co‑ordinate the cellular functions of tumour cells and other types of cell in the tumour to promote the growth of the primary tumour, local invasion, angiogenesis and metastasis, and the establishment and survival of cancer cells in the metastatic niche. Therefore, the present study aimed to provide an informative summary of the involvement of BMPs in the tumour microenvironment.

miR-485-5p/HSP90 axis blocks Akt1 phosphorylation to suppress osteosarcoma cell proliferation and migration via PI3K/AKT pathway

Osteosarcoma (OS) is closely related to the dysregulation of various intracellular signaling pathways, especially the PI3K/Akt signaling pathway. Reportedly, HSP90 was responsible for phospho-Akt stabilization, and both AKT1 and HSP90 were upregulated within osteosarcoma. Herein, we demonstrated that AKT1 and HSP90 mRNA and protein expression were upregulated within osteosarcoma tissues and cells; AKT1 knockdown significantly inhibited OS cell viability. HSP90 knockdown suppressed the phosphorylation of AKT1, decreased ki-67 and Vimentin protein levels, enhanced p21 and E-cadherin protein levels, and inhibited OS cell proliferation and migration; AKT1 overexpression exerted opposing effects and significantly attenuated the effects of HSP90 knockdown. miR-485-5p targeted AKT1 and HSP90 3'-UTR to inhibit AKT1 and HSP90 expression. miR-485-5p overexpression dramatically reduced AKT1, HSP90, and ki-67 proteins, increased E-cadherin protein levels, and inhibited OS cell proliferation and migration. In conclusion, HSP90 knockdown blocked the phosphorylation of AKT1 suppressing the proliferation and migration capacity of OS cells via the PI3K/AKT pathway; miR-485-5p binds to HSP90 and AKT1 in their 3'-UTR to inhibit HSP90 and AKT1 expression, therefore exerting a tumor suppressor function within osteosarcoma.

Interplay between BMPs and Reactive Oxygen Species in Cell Signaling and Pathology

The integration of cell extrinsic and intrinsic signals is required to maintain appropriate cell physiology and homeostasis. Bone morphogenetic proteins (BMPs) are cytokines that belong to the transforming growth factor-β (TGF-β) superfamily, which play a key role in embryogenesis, organogenesis and regulation of whole-body homeostasis. BMPs interact with membrane receptors that transduce information to the nucleus through SMAD-dependent and independent pathways, including PI3K-AKT and MAPKs. Reactive oxygen species (ROS) are intracellular molecules derived from the partial reduction of oxygen. ROS are highly reactive and govern cellular processes by their capacity to regulate signaling pathways (e.g., NF-κB, MAPKs, KEAP1-NRF2 and PI3K-AKT). Emerging evidence indicates that BMPs and ROS interplay in a number of ways. BMPs stimulate ROS production by inducing NOX expression, while ROS regulate the expression of several BMPs. Moreover, BMPs and ROS influence common signaling pathways, including PI3K/AKT and MAPK. Additionally, dysregulation of BMPs and ROS occurs in several pathologies, including vascular and musculoskeletal diseases, obesity, diabetes and kidney injury. Here, we review the current knowledge on the integration between BMP and ROS signals and its potential applications in the development of new therapeutic strategies.

PMEPA1 induces EMT via a non-canonical TGF-β signalling in colorectal cancer

Prostate transmembrane protein androgen induced 1 (PMEPA1) has been reported to promote cancer progression. Metastasis is the main factor leading to cancer progression and poor prognosis, and at the beginning of metastasis, epithelial‐to‐mesenchymal transition (EMT) is a crucial activation. However, the relationship between PMEPA1 and EMT in colorectal cancer metastasis is still poorly understood. In this study, we first testified that PMEPA1 expresses higher in tumour than normal tissue in Gene Expression Omnibus database, in the Cancer Genome Atlas (TCGA) as well as in the clinical data we collected. Moreover, the higher expression was associated with poor prognosis. We furthermore demonstrated PMEPA1 promotes colorectal cancer metastasis and EMT in vivo and in vitro. We found that PMEPA1 activates the bone morphogenetic proteins (BMP) signalling of TGF‐β signalling resulting in promoting EMT and accelerating the proliferation and metastasis of colorectal cancer.

LncRNA ZFAS1 promotes proliferation and migration and inhibits apoptosis in nasopharyngeal carcinoma via the PI3K/AKT pathway in vitro

BACKGROUND

Increasing evidence shows that long non-coding RNAs (lncRNAs) play a key role in the development of various cancers. Zinc finger antisense 1 (ZFAS1) is a novel lncRNA with previously demonstrated associations with several types of cancer. Here we examined the expression and potential function of the ZFAS1 in nasopharyngeal carcinoma (NPC).

METHODS

We detected ZFAS1 expression in GSE12452, a human microarray dataset, and NPC cell lines. Small interfering RNA against ZFAS1 was used to elucidate the cellular functions of ZFAS1 using MTT, colony formation, cell cycle, cell apoptosis, transwell invasion and migration and western blot assays. An activator of the PI3K/AKT signaling pathway (740Y-P) was used to determine the contribution of PI3K/AKT.

RESULTS

ZFAS1 was significantly upregulated in NPC tissues and cell lines. Silencing ZFAS1 significantly inhibited cell proliferation and invasion, arrested cell cycle progression and promoted cell apoptosis, as well as reduced epithelial-mesenchymal transition. Moreover, 740Y-P could rescue the effects of ZFAS1 knockdown on proliferation, apoptosis and invasion in 5-8F cells.

CONCLUSIONS

ZFAS1 might play an oncogenic role in NPC and facilitate cell proliferation and invasion via the PI3K/AKT signaling pathway in NPC cells.

BMP signaling and its paradoxical effects in tumorigenesis and dissemination

Bone morphogenetic proteins (BMPs) play important roles in embryonic and postnatal development by regulating cell differentiation, proliferation, motility, and survival, thus maintaining homeostasis during organ and tissue development. BMPs can lead to tumorigenesis and regulate cancer progression in different stages. Therefore, we summarized studies on BMP expression, the clinical significance of BMP dysfunction in various cancer types, and the molecular regulation of various BMP-related signaling pathways. We emphasized on the paradoxical effects of BMPs on various aspects of carcinogenesis, including epithelial–mesenchymal transition (EMT), cancer stem cells (CSCs), and angiogenesis. We also reviewed the molecular mechanisms by which BMPs regulate tumor generation and progression as well as potential therapeutic targets against BMPs that might be valuable in preventing tumor growth and invasion.

The BMP pathway: A unique tool to decode the origin and progression of leukemia

The microenvironment (niche) governs the fate of stem cells (SCs) by balancing self-renewal and differentiation. Increasing evidence indicates that the tumor niche plays an active role in cancer, but its important properties for tumor initiation progression and resistance remain to be identified. Clinical data show that leukemic stem cell (LSC) survival is responsible for disease persistence and drug resistance, probably due to their sustained interactions with the tumor niche. Bone morphogenetic protein (BMP) signaling is a key pathway controlling stem cells and their niche. BMP2 and BMP4 are important in both the normal and the cancer context. Several studies have revealed profound alterations of the BMP signaling in cancer SCs, with major deregulations of the BMP receptors and their downstream signaling elements. This was illustrated in the hematopoietic system by pioneer studies in chronic myelogenous leukemia that may now be expanded to acute myeloid leukemia and lymphoid leukemia, as reviewed here. At diagnosis, cells from the leukemic microenvironment are the major providers of soluble BMPs. Conversely, LSCs display altered receptors and downstream BMP signaling elements accompanied by altered functional responses to BMPs. These studies reveal the role of BMPs in tumor initiation, in addition to their known effects in later stages of transformation and progression. They also reveal the importance of BMPs in fueling cell transformation and expansion by overamplifying a natural SC response. This mechanism may explain the survival of LSCs independently of the initial oncogenic event and therefore may be involved in resistance processes.

BMP2 promotes proliferation and invasion of nasopharyngeal carcinoma cells via mTORC1 pathway

Bone morphogenetic protein-2 (BMP2) is a secreted protein that highly expressed in a variety of cancers and contributes to cell proliferation, migration, invasiveness, mobility, metastasis and EMT. However, its clinical significance and biological function in nasopharyngeal carcinoma (NPC) remain unknown up to now. Up-regulation of BMP2 was first observed in NPC cell lines by a genome-wide transcriptome analysis in our previous study. In this study, BMP2 mRNA was detected by qRT-PCR and data showed that it was upregulated in NPC compared with non-cancerous nasopharynx samples. Immunohistochemistry (IHC) analysis in NPC specimens revealed that high BMP2 expression was significantly associated with clinical stage, distant metastasis and shorter survival of NPC patients. Moreover, overexpression of BMP2 in NPC cells promoted cell proliferation, migration, invasiveness and epithelial-mesenchymal transition (EMT). Mechanistically, BMP2 overexpression increase phosphorylated protein level of mTOR, S6K and 4EBP1. Correspondingly, mTORC1 inhibitor rapamycin blocked the effect of BMP2 on NPC cell proliferation and invasion. In conclusion, our results suggest that BMP2 overexpression in NPC enhances proliferation, invasion and EMT of tumor cells through the mTORC1 signaling pathway.

Bone morphogenetic protein 2 promotes human trophoblast cell invasion by upregulating N-cadherin via non-canonical SMAD2/3 signaling

BMP2 expression is spatiotemporally correlated with embryo implantation and is crucial for endometrial decidualization and fertility in mice. BMP2 has been reported to increase the mesenchymal adhesion molecule N-cadherin and enhance cell invasion in cancer cells; moreover, studies suggest that N-cadherin promotes placental trophoblast invasion. However, whether BMP2 can promote trophoblast cell invasion during placentation remains unknown. The objective of our study was to investigate the effects of BMP2 on human trophoblast cell invasion and the involvement of N-cadherin and SMAD signaling. Primary and immortalized (HTR8/SVneo) cultures of human extravillous trophoblast (EVT) cells were used as study models. Treatment with recombinant human BMP2 increased HTR8/SVneo cell transwell Matrigel invasion as well as N-cadherin mRNA and protein levels, but had no significant effect on cell proliferation. Likewise, BMP2 treatment enhanced primary human EVT cell invasion and N-cadherin production. Basal and BMP2-induced invasion were attenuated by small interfering RNA-mediated downregulation of N-cadherin in both HTR8/SVneo and primary EVT cells. Intriguingly, BMP2 induced the phosphorylation/activation of both canonical SMAD1/5/8 and non-canonical SMAD2/3 signaling in HTR8/SVneo and primary EVT cells. Knockdown of SMAD2/3 or common SMAD4 totally abolished the effects of BMP2 on N-cadherin upregulation in HTR8/SVneo cells. Upregulation of SMAD2/3 phosphorylation and N-cadherin were totally abolished by type I receptor activin receptor-like kinases 2/3 (ALK2/3) inhibitor DMH1; moreover, knockdown of ALK2 or ALK3 inhibited N-cadherin upregulation. Interestingly, activation of SMAD2/3 and upregulation of N-cadherin were partially attenuated by ALK4/5/7 inhibitor SB431542 or knockdown of ALK4, but not ALK5. Our results show that BMP2 promotes trophoblast cell invasion by upregulating N-cadherin via non-canonical ALK2/3/4-SMAD2/3-SMAD4 signaling.

GDF11/BMP11 activates both smad1/5/8 and smad2/3 signals but shows no significant effect on proliferation and migration of human umbilical vein endothelial cells

GDF11/BMP11, a member of TGF-β superfamily, was reported to rejuvenate heart, skeletal muscle and blood vessel architecture in aged mice. However, the rejuvenative effects of GDF11 were questioned recently. Here, we investigated the effects of GDF11 on smad and non-smad signals in human umbilical vein endothelial cells (HUVECs) and the effects of GDF11 on proliferation and migration of HUVECs and primary rat aortic endothelial cells (RAECs). GDF11 factor purchased from two different companies (PeproTech and R&D Systems) was comparatively studied. Western blot was used to detect the protein expressions. The cell viability and migration were examined by using MTT and wound healing assays. Results showed that GDF11 activated both smad1/5/8 and smad2/3 signals in HUVECs. GDF11 increased protein expression of NADPH oxidase 4(NOX4) in HUVECs. GDF11 showed no significant effect on the protein level of p38, p-p38, ERK, p-ERK, Akt, p-Akt (Ser473) and p-Akt(Thr308), but increased the protein level of p-JNK and p-AMPK in HUVECs, and these increases were inhibited by antioxidant mitoTEMPO treatment. GDF11 slightly increased cell viability after short-term treatment and slightly decreased cell viability after long-term treatment. GDF11 showed no significant effect on cell proliferation and migration. These data indicated that the notion of GDF11 as a rejuvenation-related factor for endothelial cells needs to be cautious.

The prenylflavonoid Icaritin enhances osteoblast proliferation and function by signal transducer and activator of transcription factor 3 (STAT-3) regulation of C-X-C chemokine receptor type 4 (CXCR4) expression

In this study, we examined the effects of a natural prenylflavonoid Icaritin (ICT), on human osteoblast proliferation and osteogenic function. We observed that ICT dose-dependently enhanced osteoblast proliferation by ~15% over a 7day period. This increase in cell proliferation was associated with corresponding increases in osteoblast functions as measured by ALP secretion, intracellular calcium ions influx and calcium deposition. These anabolic effects were associated with a 4-fold increase in CXCR4 mRNA and protein expression. Silencing of CXCR4 protein expression using small interfering RNA reversed ICT-induced increase in cell proliferation, ALP activity and calcium deposition. Interestingly, we observed that ICT dose-dependently increased STAT-3 phosphorylation; and this resulted in increased binding of phosphorylated STAT-3 to the promoter region of the CXCR4 gene, to increase CXCR4 protein expression. Furthermore, we found that inhibition of STAT-3 phosphorylation resulted in a decrease in CXCR4 protein expression; whilst increasing phosphorylation of STAT-3 using a constitutive active STAT-3 vector significantly increased CXCR4 levels. Moreover, the chemical inhibition of STAT-3 phosphorylation annulled our previously observed ICT-induced increases of osteoblast proliferation and function. Finally, in a rat model of estrogen-deficient osteoporosis, ICT restored both osteoblasts numbers and CXCR4 expression. Taken together, both cellular and animal models support the novel findings that ICT; through the phosphorylation of STAT-3, up-regulated CXCR4, to increase osteoblast proliferation and function.

Bone morphogenetic protein-2 and tumor growth: Diverse effects and possibilities for therapy

Concern regarding safety with respect to the clinical use of human bone morphogenetic protein-2 (BMP-2) has become an increasingly controversial topic. The role of BMP-2 in carcinogenesis is of particular concern. Although there have been many studies of this topic, the results have been contradictory and confusing. We conducted a systematic review of articles that are relevant to the relationship or effect of BMP-2 on all types of tumors and a total of 97 articles were included. Studies reported in these articles were classified into three major types: "expression studies", "in vitro studies", and "in vivo studies". An obvious pattern was that those works that hypothesize an inhibitory effect for BMP-2 most often examined only the proliferative properties of the tumor cells. This subset of studies also contained an extraordinary number of contradictory findings which made drawing a reliable general conclusion impossible. In general, we support a pro-tumorigenesis role for BMP-2 based on the data from these in vitro cell studies and in vivo animal studies, however, more clinical studies should be carried out to help make a firm conclusion.

Phospho-Akt overexpression is prognostic and can be used to tailor the synergistic interaction of Akt inhibitors with gemcitabine in pancreatic cancer

BACKGROUND

There is increasing evidence of a constitutive activation of Akt in pancreatic ductal adenocarcinoma (PDAC), associated with poor prognosis and chemoresistance. Therefore, we evaluated the expression of phospho-Akt in PDAC tissues and cells, and investigated molecular mechanisms influencing the therapeutic potential of Akt inhibition in combination with gemcitabine.

METHODS

Phospho-Akt expression was evaluated by immunohistochemistry in tissue microarrays (TMAs) with specimens tissue from radically-resected patients (n = 100). Data were analyzed by Fisher and log-rank test. In vitro studies were performed in 14 PDAC cells, including seven primary cultures, characterized for their Akt1 mRNA and phospho-Akt/Akt levels by quantitative-RT-PCR and immunocytochemistry. Growth inhibitory effects of Akt inhibitors and gemcitabine were evaluated by SRB assay, whereas modulation of Akt and phospho-Akt was investigated by Western blotting and ELISA. Cell cycle perturbation, apoptosis-induction, and anti-migratory behaviors were studied by flow cytometry, AnnexinV, membrane potential, and migration assay, while pharmacological interaction with gemcitabine was determined with combination index (CI) method.

RESULTS

Immunohistochemistry of TMAs revealed a correlation between phospho-Akt expression and worse outcome, particularly in patients with the highest phospho-Akt levels, who had significantly shorter overall and progression-free-survival. Similar expression levels were detected in LPC028 primary cells, while LPC006 were characterized by low phospho-Akt. Remarkably, Akt inhibitors reduced cancer cell growth in monolayers and spheroids and synergistically enhanced the antiproliferative activity of gemcitabine in LPC028, while this combination was antagonistic in LPC006 cells. The synergistic effect was paralleled by a reduced expression of ribonucleotide reductase, potentially facilitating gemcitabine cytotoxicity. Inhibition of Akt decreased cell migration and invasion, which was additionally reduced by the combination with gemcitabine. This combination significantly increased apoptosis, associated with induction of caspase-3/6/8/9, PARP and BAD, and inhibition of Bcl-2 and NF-kB in LPC028, but not in LPC006 cells. However, targeting the key glucose transporter Glut1 resulted in similar apoptosis induction in LPC006 cells.

CONCLUSIONS

These data support the analysis of phospho-Akt expression as both a prognostic and a predictive biomarker, for the rational development of new combination therapies targeting the Akt pathway in PDAC. Finally, inhibition of Glut1 might overcome resistance to these therapies and warrants further studies.

Association Between BMP-2 and Carcinogenicity

STUDY DESIGN

Literature review.

OBJECTIVE

To evaluate the association between recombinant human bone morphogenetic protein-2 (rhBMP-2) and malignancy.

SUMMARY OF BACKGROUND DATA

The use of rhBMP-2 in spine surgery has been the topic of much debate as studies assessing the association between rhBMP-2 and malignancy have come to conflicting conclusions.

METHODS

A systematic review of the literature was performed using the PubMed-National Library of Medicine/National Institute of Health databases. Only non-clinical studies directly addressing BMP-2 and cancer were included. Articles were categorized by study type (animal, in vitro cell line/human/animal), primary malignancy, cancer attributes, and whether BMP-2 was pro-malignancy or not.

RESULTS

A total of 4,131 articles were reviewed. Of those, 515 articles made reference to both BMP-2 and cancer, 99 of which were found to directly examine the role of BMP-2 in cancer. Seventy-five studies were in vitro and 24 were animal studies. Forty-three studies concluded that BMP-2 enhanced cancer function, whereas 18 studies found that BMP-2 suppressed malignancy. Thirty-six studies did not examine whether BMP-2 enhanced or suppressed cancer function. Fifteen studies demonstrated BMP-2 dose dependence (9 enhancement, 6 suppression) and one study demonstrated no dose dependence. Nine studies demonstrated BMP-2 time dependence (6 enhancement, 3 suppression). However, no study demonstrated that BMP-2 caused cancer de novo.

CONCLUSION

Currently, conflicting data exist with regard to the effect of exogenous BMP-2 on cancer. The majority of studies addressed the role of BMP-2 in prostate (17%), breast (17%), and lung (15%) cancers. Most were in vitro studies (75%) and examined cancer invasiveness and metastatic potential (37%). Of 99 studies, there was no demonstration of BMP-2 causing cancer de novo. However, 43% of studies suggested that BMP-2 enhances tumor function, motivating more definitive research on the topic that also includes clinically meaningful dose- and time-dependence.

LEVEL OF EVIDENCE

2.

Secreted phosphoprotein 24 kD (Spp24) inhibits growth of human pancreatic cancer cells caused by BMP-2

The emerging role of bone morphogenetic proteins (BMPs) in the initiation and progression of multiple cancers has drawn great attention in cancer research. In this study, we report that BMP-2 can promote the proliferation of the pancreatic tumor cell line, PANC-1. Secreted phosphoprotein 24 kD (Spp24), a BMP binding protein, did not affect the proliferation of the cells but promoted the apoptosis of the cells in vitro. In a xeneograft tumor model using PANC-1 cells, BMP-2 dramatically promoted tumor growth, while Spp24 not only abolished the effect of BMP-2, but also dramatically induced tumor shrinking when used alone. Activation of Smad1/5/8 participated in this process as demonstrated by immunohistochemical staining of phosphorylated Smad 1/5/8. We conclude that Spp24 can be developed into a therapeutic agent that could be employed in clinical situations where the inhibition of BMPs and related proteins is advantageous.

A new role for the PI3K/Akt signaling pathway in the epithelial-mesenchymal transition

Tumor metastasis is not only a sign of disease severity but also a major factor causing treatment failure and cancer-related death. Therefore, studies on the molecular mechanisms of tumor metastasis are critical for the development of treatments and for the improvement of survival. The epithelial-mesenchymal transition (EMT) is an orderly, polygenic biological process that plays an important role in tumor cell invasion, metastasis and chemoresistance. The complex, multi-step process of EMT involves multiple regulatory mechanisms. Specifically, the PI3K/Akt signaling pathway can affect the EMT in a variety of ways to influence tumor aggressiveness. A better understanding of the regulatory mechanisms related to the EMT can provide a theoretical basis for the early prediction of tumor progression as well as targeted therapy.

Simultaneous silencing of XIAP and survivin causes partial mesenchymal-epithelial transition of human pancreatic cancer cells via the PTEN/PI3K/Akt pathway

Pancreatic cancer has one of the highest mortality rates among malignant tumors and is characterized by rapid invasion, early metastasis and chemoresistance. X-linked inhibitor of apoptosis (XIAP) and survivin are two of the most important members of the IAP family. Previous studies have shown that XIAP and survivin were overexpressed in pancreatic cancer and were closely associated with cell proliferation and chemoresistance to gemcitabine. In the present study, stable inhibition of XIAP and survivin in Panc-1 cells was performed using lentivirus-carried short hairpin RNAs. The expression of XIAP, survivin, E-cadherin, Slug, phosphatase and tensin homolog (PTEN) and phosphorylated Akt was then measured. In addition, cell proliferation, apoptosis, invasion and migration were assessed. The results showed that stable inhibition of XIAP and survivin expression in Panc-1 cells significantly reduced cell proliferation, increased apoptosis and partially reversed the epithelial-mesenchymal transition (EMT). Furthermore, the results of the present study demonstrated that the partial reversal of the EMT was accompanied by inhibited cell invasion and migration as well as increased chemosensitivity to gemcitabine in pancreatic cancer cells; this was indicated to be mediated via the PTEN/phosphatidylinositol 3-kinase/Akt signaling pathway. In conclusion, these results suggested that simultaneous inhibition of XIAP and survivin may be a promising strategy for the treatment of pancreatic cancer.

Zebrafish reporter lines reveal in vivo signaling pathway activities involved in pancreatic cancer

Pancreatic adenocarcinoma, one of the worst malignancies of the exocrine pancreas, is a solid tumor with increasing incidence and mortality in industrialized countries. This condition is usually driven by oncogenic KRAS point mutations and evolves into a highly aggressive metastatic carcinoma due to secondary gene mutations and unbalanced expression of genes involved in the specific signaling pathways. To examine in vivo the effects of KRAS^G12D during pancreatic cancer progression and time correlation with cancer signaling pathway activities, we have generated a zebrafish model of pancreatic adenocarcinoma in which eGFP-KRAS^G12D expression was specifically driven to the pancreatic tissue by using the GAL4/UAS conditional expression system. Outcrossing the inducible oncogenic KRAS^G12D line with transgenic zebrafish reporters, harboring specific signaling responsive elements of transcriptional effectors, we were able to follow TGFβ, Notch, Bmp and Shh activities during tumor development. Zebrafish transgenic lines expressing eGFP-KRAS^G12D showed normal exocrine pancreas development until 3 weeks post fertilization (wpf). From 4 to 24 wpf we observed several degrees of acinar lesions, characterized by an increase in mesenchymal cells and mixed acinar/ductal features, followed by progressive bowel and liver infiltrations and, finally, highly aggressive carcinoma. Moreover, live imaging analysis of the exocrine pancreatic tissue revealed an increasing number of KRAS-positive cells and progressive activation of TGFβ and Notch pathways. Increase in TGFβ, following KRAS^G12D activation, was confirmed in a concomitant model of medulloblastoma (MDB). Notch and Shh signaling activities during tumor onset were different between MDB and pancreatic adenocarcinoma, indicating a tissue-specific regulation of cell signaling pathways. Moreover, our results show that a living model of pancreatic adenocarcinoma joined with cell signaling reporters is a suitable tool for describing in vivo the signaling cascades and molecular mechanisms involved in tumor development and a potential platform to screen for novel oncostatic drugs.

SOX2 promotes the migration and invasion of laryngeal cancer cells by induction of MMP-2 via the PI3K/Akt/mTOR pathway

SOX2 is a high mobility group box containing transcription factor that has been reported to be aberrantly overexpressed in various human malignancies, including laryngeal squamous cell carcinoma (LSCC). However, the potential role of SOX2 in LSCC migration and invasion remains to be elucidated. In the present study, we generated stable transformants of human LSCC cells constitutively overexpressing SOX2 and investigated the effects of SOX2 overexpression on migration and invasion in LSCC cells as well as the possible underlying mechanisms. We found that ectopic overexpression of SOX2 in LSCC cells enhanced their migratory and invasive ability in vitro, accompanied by increased expression and activity of matrix metalloproteinase (MMP)-2. Meanwhile, SOX2-induced cell migration and invasion were significantly abrogated by a neutralizing anti-MMP-2 antibody or small interfering RNA targeting MMP-2. Furthermore, overexpression of SOX2 induced phosphorylation of Akt and mammalian target of rapamycin (mTOR), which are downstream effectors of the PI3K pathway. Finally, LY294002, an inhibitor of PI3K, also markedly abolished SOX2-induced activation of the Akt/mTOR pathway and increased cell invasion and MMP-2 expression. Taken together, we conclude that SOX2 promotes migration and invasion of laryngeal cancer cells by inducing MMP-2 via the PI3K/Akt/mTOR pathway. Our findings suggest that SOX2 may serve as a potential therapeutic target for LSCC.

Cancer risk after use of recombinant bone morphogenetic protein-2 for spinal arthrodesis

BACKGROUND

Recombinant human bone morphogenetic protein-2 (rhBMP-2) is a growth factor known to have in vitro effects on the growth and invasiveness of cancer. It has been approved by the U.S. Food and Drug Administration in limited doses for single-level anterior spinal arthrodesis, but it is commonly used off-label and at high doses. The effect of rhBMP-2 on the risk of cancer has been a concern. We sought to evaluate the risk of new cancers in patients receiving high-dose rhBMP-2.

METHODS

We used publicly available data from a pivotal, multicenter, randomized controlled trial of patients with degenerative lumbar spine conditions who underwent a single-level instrumented posterolateral arthrodesis with either high-dose rhBMP-2 in a compression-resistant matrix (CRM) (rhBMP-2/CRM; n = 239) or autogenous bone graft (control group; n = 224). We compared the risks of new cancers in the rhBMP-2/CRM and control groups at two and five years after surgery.

RESULTS

At two years, with 86% follow-up, there were fifteen new cancer events in eleven patients in the rhBMP-2/CRM group compared with two new cancer events in two patients in the control group treated with autogenous bone graft. The incidence rate of new cancer events per 100 person-years was 3.37 (95% confidence interval [CI], 1.89 to 5.56) in the rhBMP-2/CRM group at two years compared with 0.50 (95% CI, 0.06 to 1.80) in the control group. The incidence rate ratio was 6.75 (95% CI, 1.57 to 60.83; p = 0.0026) at two years. Calculated in terms of the number of patients with one or more cancer events two years after the surgery, the incidence rate per 100 person-years was 2.54 (95% CI, 1.27 to 4.54) in the rhBMP-2/CRM group compared with 0.50 (95% CI, 0.06 to 1.82) in the control group at two years; the incidence rate ratio was 5.04 (95% CI, 1.10 to 46.82; p = 0.0194). At five years, there was a 37% loss of follow-up, but a significantly greater incidence of cancer events was still observed in the rhBMP-2/CRM group.

CONCLUSIONS

A high dose of 40 mg of rhBMP-2/CRM in lumbar spinal arthrodesis was associated with an increased risk of new cancer.

Adenovirus mediated knockdown of bone morphogenetic protein 2 inhibits human lung cancer growth and invasion in vitro and in vivo

Bone morphogenetic protein 2 (BMP-2) is a member of the TGF-beta superfamily of signaling molecules, and has been shown to function as a tumor suppressor involved in development and progression of many malignancies. BMP-2 has previously been reported to be closely correlated with lung cancer. But, the role and molecular mechanisms of BMP-2 in lung cancer have not yet been comprehensively explained. The present study aims to elucidate the role of BMP-2 in growth and invasion of human lung adenocarcinoma (LAC) in vitro and in vivo. Adenovirus vector-mediated BMP-2 small hairpin RNA (shBMP-2) was used to transfect into A549 LAC cells to determine the functional relevance of BMP-2 and tumor growth and invasion in vitro and in vivo, and further investigate the expression levels of BMP-2, vascular endothelial growth factor (VEGF), matrix metallopeptidase-9 (MMP-9), phosphatidylinositol 3-kinase p85alpha (PI3Kp85alpha) and phosphorylated AKT (p-AKT). As a result, LAC cell proliferation and invasion were significantly diminished by knockdown of BMP-2 indicated by MTT and Transwell assays, and cell apoptosis and cycle arrest were markedly induced indicated by flow cytometry. When BMP-2 expression was knocked down, the expression of PI3Kp85alpha, p-AKT, VEGF and MMP-9 was also down-regulated in LAC cells. In addition, the tumor volumes in LAC subcutaneous nude mouse model treated with shBMP-2 were significantly smaller than those in control and ad-GFP groups. Taken together, our findings indicate that knockdown of BMP-2 inhibits growth and invasion of LAC cells possibly via blockade of the PI3K/AKT signaling pathway, and BMP-2 may be a potential therapeutic target for lung cancer.

APRIL induces tumorigenesis and metastasis of colorectal cancer cells via activation of the PI3K/Akt pathway

A proliferation-inducing ligand (APRIL) is highly expressed in colorectal cancer (CRC) tissues and cell lines. However, the biological functions and precise signals elicited by APRIL in CRC have not been fully understood. Here, we used small interfering RNA to selectively deplete APRIL and to determine its tumorigenic effects in a CRC cell line SW480 both in vitro and in vivo. Knockdown of APRIL in SW480 cells was associated with modulation of cell proliferation as well as reduction of cell migration and invasion in vitro. Moreover APRIL-knockdown SW480 cells displayed markedly inhibited tumor growth and decreased metastasis to the liver in immunodeficient mice upon subcutaneous injection. Importantly, we observed that downregulation of APRIL in SW480 cells resulted in greatly decreased activity of phosphoinositide 3-kinase (PI3K)/Akt pathway. In addition, we observed that recombinant human APRIL mediated activation of the PI3K/Akt pathway in CRC cells resulting in induced expression of important cell cycle proteins and matrix metalloproteinases in a PI3K/Akt dependent manner. This was concurrent with marked cell growth viability as well as increased cell migration and invasion. Together, these compelling data suggest that APRIL-induced tumorigenesis and metastasis of CRC cells may be accomplished through activation of the PI3K/Akt pathway. These findings may lead to a better understanding of the biological effects of APRIL and may provide clues for identifying novel therapeutic and preventive molecular markers for CRC.

ADAM15 is involved in MICB shedding and mediates the effects of gemcitabine on MICB shedding in PANC-1 pancreatic cancer cells

The aim of this study was to investigate the role of ADAM15 in MHC class I polypeptide-related sequence B (MICB) protein ectodomain shedding and observe whether or not gemcitabine affects MICB shedding from PANC-1 cells. In this study, immunohistochemistry of MICB and ADAM15 were performed on tumor samples obtained from 93 patients with pancreatic ductal adenocarcinoma (PDAC). The expression of MICB and ADAM15 in the PDAC tissues was significantly higher compared with that in the normal tissues of the pancreas. Statistical analysis showed a significant correlation between the expression of MICB and certain classic clinicopathological characteristics (i.e., histological grade and TNM stage). ADAM15 expression was found to correlate with lymph node metastasis and TNM stage. The Spearman's rank test suggested that the expression of MICB was inversely correlated with that of ADAM15 in PDAC tissues. Knockdown of ADAM15 in PANC-1 cells clearly upregulated MICB expression on the cellular surface and downregulated soluble MICB (sMICB) levels in the culture supernatants. A non-toxic dose of 0.5 µmol/l gemcitabine suppresses ADAM15 expression leading, at the same time, to an increase in MICB expression and a decrease in sMICB production in PANC-1 cells. The mRNA levels of MICB did not change following PANC-1 exposure to gemcitabine. Further study suggests that the suppressive effect of gemcitabine on MICB shedding in PANC-1 cells is mediated by ADAM15 downregulation. In conclusion, the results of the present study support the hypothesis that ADAM15 is involved in MICB shedding of PANC-1 cells and that gemcitabine inhibits MICB ectodomain shedding through the suppression of ADAM15.

Developmental pathways in colon cancer: crosstalk between WNT, BMP, Hedgehog and Notch

A hallmark of cancer is reactivation/alteration of pathways that control cellular differentiation during developmental processes. Evidence indicates that WNT, Notch, BMP and Hedgehog pathways have a role in normal epithelial cell differentiation, and that alterations in these pathways accompany establishment of the tumorigenic state. Interestingly, there is recent evidence that these pathways are intertwined at the molecular level, and these nodes of intersection may provide opportunities for effective targeted therapies. This review will highlight the role of the WNT, Notch, BMP and Hedgehog pathways in colon cancer.

Immunohistochemical expression of mTOR negatively correlates with PTEN expression in gastric carcinoma

The phosphoinositide-3 kinase (PI3K)-AKT-mammalian target of rapamycin (mTOR) pathway is a cellular pathway involved in cell growth, tumorigenesis and cell invasion which is frequently activated in various types of cancer. The downstream effector of the pathway is mTOR which is important in cellular growth and homeostasis and aberrant activation of mTOR has been reported in several types of cancer. The tumor suppressor gene phosphatase and tensin homolog (PTEN) is essential in this pathway for inhibiting tumor invasion and metastasis. However, the involvement of mTOR and PTEN in the progression of human gastric cancer remains to be identified. Immunohistochemical staining was performed to detect the expression of mTOR and PTEN in paraffin-embedded gastric tissue sections obtained from 33 patients with gastric cancer and 30 normal controls. The expressed mTOR was mainly distributed in the cytoplasm, while PTEN was mainly localized to the nucleus. By considering negative mTOR expression with positive PTEN expression as one group and negative PTEN expression with positive mTOR expression as the other, significant statistical differences were observed in various categories, including histological types and metastatic and clinical pathology stages, between the 2 groups (P<0.01 or 0.05). The results indicated that the expression levels of mTOR and PTEN were negatively correlated in the PI3K-AKT-mTOR signaling pathway. Combined detection of mTOR and PTEN expression may be used to evaluate the degree of malignancy in gastric cancer and may be a useful marker for the early diagnosis of gastric cancer.

P38 and ERK1/2 MAPKs act in opposition to regulate BMP9-induced osteogenic differentiation of mesenchymal progenitor cells

Although previous studies have demonstrated that BMP9 is highly capable of inducing osteogenic differentiation and bone formation, the precise molecular mechanism involved remains to be fully elucidated. In this current study, we explore the possible involvement and detail effects of p38 and ERK1/2 MAPKs on BMP9-indcued osteogenic differentiation of mesenchymal progenitor cell (MPCs). We find that BMP9 simultaneously stimulates the activation of p38 and ERK1/2 in MPCs. BMP9-induced early osteogenic marker, such as alkaline phosphatase (ALP), and late osteogenic markers, such as matrix mineralization and osteocalcin (OC) are inhibited by p38 inhibitor SB203580, whereas enhanced by ERK1/2 inhibitor PD98059. BMP9-induced activation of Runx2 and Smads signaling are reduced by SB203580, and yet increased by PD98059 in MPCs. The in vitro effects of inhibitors are reproduced with adenoviruses expressing siRNA targeted p38 and ERK1/2, respectively. Using mouse calvarial organ culture and subcutaneous MPCs implantation, we find that inhibition of p38 activity leads to significant decrease in BMP9-induced osteogenic differentiation and bone formation, however, blockage of ERK1/2 results in effective increase in BMP9-indcued osteogenic differentiation in vivo. Together, our results reveal that p38 and ERK1/2 MAPKs are activated in BMP9-induced osteogenic differentiation of MPCs. What is most noteworthy, however, is that p38 and ERK1/2 act in opposition to regulate BMP9-induced osteogenic differentiation of MPCs.

CDK-4 inhibitor P276 sensitizes pancreatic cancer cells to gemcitabine-induced apoptosis

Despite advances in molecular pathogenesis, pancreatic cancer remains a major unsolved health problem. It is a rapidly invasive, metastatic tumor that is resistant to standard therapies. The phosphatidylinositol-3-kinase/Akt and mTOR signaling pathways are frequently dysregulated in pancreatic cancer. Gemcitabine is the mainstay treatment for metastatic pancreatic cancer. P276 is a novel CDK inhibitor that induces G(2)/M arrest and inhibits tumor growth in vivo models. Here, we determined that P276 sensitizes pancreatic cancer cells to gemcitabine-induced apoptosis, a mechanism-mediated through inhibition of Akt-mTOR signaling. In vitro, the combination of P276 and gemcitabine resulted in a dose- and time-dependent inhibition of proliferation and colony formation of pancreatic cancer cells but not with normal pancreatic ductal cells. This combination also induced apoptosis, as seen by activated caspase-3 and increased Bax/Bcl2 ratio. Gene profiling studies showed that this combination downregulated Akt-mTOR signaling pathway, which was confirmed by Western blot analyses. There was also a downregulation of VEGF and interleukin-8 expression suggesting effects on angiogenesis pathway. In vivo, intraperitoneal administration of the P276-Gem combination significantly suppressed the growth of pancreatic cancer tumor xenografts. There was a reduction in CD31-positive blood vessels and reduced VEGF expression, again suggesting an effect on angiogenesis. Taken together, these data suggest that P276-Gem combination is a novel potent therapeutic agent that can target the Akt-mTOR signaling pathway to inhibit both tumor growth and angiogenesis.

BMP signalling controls the malignant potential of ascites-derived human epithelial ovarian cancer spheroids via AKT kinase activation

Epithelial ovarian cancer (EOC) cells have the ability to form multi-cellular aggregates in malignant ascites which dramatically alters cell signalling, survival, and metastatic potential. Herein, we demonstrate that patient ascites-derived EOC cells down-regulate endogenous bone morphogenetic protein (BMP) signalling by decreasing BMP ligand expression when grown in suspension culture to form spheroids. Enforced BMP signalling in these cells via constitutively-active BMP type I ALK3(QD) receptor expression causes the formation of smaller, more loosely-aggregated spheroids. Additionally, ALK3(QD)-expressing spheroids have an increased rate of adhesion and dispersion upon reattachment to substratum. Inhibition of endogenous BMP signalling using recombinant Noggin or small molecule inhibitor LDN-193189, on the other hand, opposed these phenotypic changes. To identify potential targets that impact the phenotype of EOC spheroids due to activated BMP signalling, we performed genome-wide expression analyses using Affymetrix arrays. Using the online Connectivity Map resource, the BMP signalling gene expression signature revealed that the AKT pathway is induced by activated BMP signalling in EOC cells; this finding was further validated by phospho-AKT immuno-blotting. In fact, treatment of EOC spheroids with an AKT inhibitor, Akti-1/2, reduced BMP-stimulated cell dispersion during reattachment as compared to controls. Thus, we have identified AKT as being one important downstream component of activated BMP signalling on EOC spheroid pathobiology, which may have important implications on the metastatic potential of this malignancy.