Lung tumor-associated osteoblast-derived bone morphogenetic protein-2 increased epithelial-to-mesenchymal transition of cancer by Runx2/Snail signaling pathway

Bone morphogenetic protein 2 inhibits hepatocellular carcinoma growth and migration through downregulation of the PI3K/AKT pathway

Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide. Previous studies have suggested that abnormal expression of BMP-4, BMP-7, and BMP-9 is correlated with tumor progression in HCC, but the role played by BMP-2 in HCC has not yet been reported. To determine the role of BMP-2 in HCC, we first investigated the effect of exogenous BMP-2 on the growth of the cell lines HCC SK-Hep-1, Hep G2, and Hep 3B. Next, we studied the function of BMP-2 in SK-Hep-1 HCC cell line using a recombinant lentivirus vector to deliver BMP-2. We also used siRNA to silence endogenous BMP-2 expression in the HCC Hep 3B cell line. Then, cell growth and migration were assayed in vitro using WST-8, wound-healing, and transwell invasion assays. Cellular apoptosis and cell-cycle distribution were assessed using flow cytometry. We also investigated the effects of BMP-2 overexpression and knockdown on the expression of proliferating cell nuclear antigen (PCNA), matrix metallopeptidase-2 (MMP-2), phosphorylated AKT (p-AKT), phosphoinositide 3-kinase p85α (PI3Kp85α), Bax, Bcl-2, caspase-3, cleaved caspase-3, p21, and cyclin E. As a result, we observed that BMP-2 inhibited the proliferation of HCC cells. Furthermore, HCC cell proliferation and migration were significantly diminished by BMP-2 overexpression, as was indicated by WST-8, would healing, and transwell assays, while knockdown of BMP-2 led to an increase in proliferation and migration of Hep 3B cells. BMP-2 overexpression significantly increased the susceptibility of SK-Hep-1 cells to low-serum-induced apoptosis, while BMP-2 knockdown reduced the susceptibility of Hep 3B cells. Overexpression of BMP-2 induced G1 phase arrest through upregulation of p21. When BMP-2 expression was elevated in SK-Hep-1 cells, the expression of PI3Kp85α, p-AKT, PCNA, and MMP-2 declined. These results suggest that BMP-2 exerts an inhibitory effect on the growth and migration of HCC cells, possibly via a blockade of PI3K/AKT signaling.

[Research advance on mechanism and application of HATs and HDACs in epithelial-mesenchymal transition of lung cancer]

肺癌是危害我国人民健康与生命的重大疾病之一, 肺癌的复发和死亡多源于肿瘤转移。上皮细胞的间质化过程(epithelial-mesenchymal transition, EMT)是肺癌转移中的一个关键步骤, 此过程涉及E-cadherin表达下调, 并受到EMT转录因子调控。组蛋白乙酰转移酶(histone acetyltransferases, HATs)和组蛋白去乙酰化酶(histone deacetyltransferases, HDACs)是催化组蛋白乙酰化和去乙酰化的蛋白家族, 不仅在肿瘤进程中发挥重要功能, 近年来发现它们同样参与肺癌EMT过程。HATs与HDACs和某些EMT转录因子有相互作用。而且, 这些EMT转录因子的功能受乙酰化调控, 并影响肺癌EMT进程。本文将分别介绍HATs和HDACs参与肺癌EMT的作用机理, 从分子机制方面对它们之间的相互作用进行探讨, 并讨论HDAC抑制剂在抑制EMT和肺癌治疗方面的潜在应用价值, 以期为相关基础研究和临床实践提供借鉴。

High-dose rhBMP-2 for adults: major and minor complications: a study of 502 spine cases

BACKGROUND

Use of recombinant human bone morphogenetic protein-2 (rhBMP-2) has increased considerably since its introduction in 2002. The complications associated with high-dose rhBMP-2 (≥ 40 mg) are unknown. The purpose of our study was to determine outcomes and medical and surgical complications associated with high-dose rhBMP-2 at short-term and long-term follow-up evaluations.

METHODS

Five hundred and two consecutive adult patients who had received high-dose rhBMP-2 as a part of spinal surgery from 2002 to 2009 at one institution were enrolled. Data were entered prospectively and studied and analyzed retrospectively. Surgical procedures in the thoracic and lumbar spine were included. Major and minor complications were documented intraoperatively, perioperatively, and at the latest follow-up examination. Complications potentially associated with rhBMP-2 use were evaluated for correlation with rhBMP-2 dose. Scoliosis Research Society (SRS) and Oswestry Disability Index (ODI) outcome measures were obtained before and after surgery.

RESULTS

On average, 115 mg (range, 40 to 351 mg) of rhBMP-2 was used. The average age of the patients (410 women and ninety-two men) at the time of the index procedure was 52.4 years (range, eighteen to eighty years). There were 265 primary and 237 revision procedures, and 261 patients had interbody fusion. An average of 11.5 vertebrae were instrumented. The average duration of follow-up was forty-two months (range, fourteen to ninety-two months). The diagnoses included idiopathic scoliosis (41%), degenerative scoliosis (31%), fixed sagittal imbalance (18%), and other diagnoses (10%). The rate of intraoperative complications was 8.2%. The rate of perioperative major surgical complications was 11.6%. The rate of perioperative major medical complications was 11.6%. Minor medical complications occurred in 18.9% of the cases, and minor surgical complications occurred in 2.6%. Logistic regression analysis and Pearson correlation did not identify a significant correlation between rhBMP-2 dosage and radiculopathy (r = -0.006), seroma (r = -0.003), or cancer (r = -0.05). Significant improvements in the ODI score (from a mean of 41 points to a mean of 26 points; p < 0.001) and the SRS total score (from a mean of 3.0 points to a mean of 3.7 points; p < 0.001) were noted at the latest follow-up evaluation.

CONCLUSIONS

This is the largest study of which we are aware that examines complications associated with high-dose rhBMP-2. Major surgical complications occurred in 11.6% of patients, and 11.6% experienced major medical complications. There was a cancer prevalence of 3.4%, but no correlation between increasing rhBMP-2 dosage and cancer, radiculopathy (seen in 1% of the patients), or seroma (seen in 0.6%) was found.

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.

The RUNX family in breast cancer: relationships with estrogen signaling

The three RUNX family members are lineage specific master regulators, which also have important, context-dependent roles in carcinogenesis as either tumor suppressors or oncogenes. Here we review evidence for such roles in breast cancer (BCa). RUNX1, the predominant RUNX family member in breast epithelial cells, has a tumor suppressor role reflected by many somatic mutations found in primary tumor biopsies. The classical tumor suppressor gene RUNX3 does not consist of such a mutation hot spot, but it too seems to inhibit BCa; it is often inactivated in human BCa tumors and its haploinsufficiency in mice leads to spontaneous BCa development. The tumor suppressor activities of RUNX1 and RUNX3 are mediated in part by antagonism of estrogen signaling, a feature recently attributed to RUNX2 as well. Paradoxically, however RUNX2, a master osteoblast regulator, has been implicated in various aspects of metastasis in general and bone metastasis in particular. Reciprocating the anti-estrogenic tumor suppressor activity of RUNX proteins, inhibition of RUNX2 by estrogens may help explain their context-dependent anti-metastatic roles. Such roles are reserved to non-osseous metastasis, because ERα is associated with increased, not decreased skeletal dissemination of BCa cells. Finally, based on diverse expression patterns in BCa subtypes, the successful use of future RUNX-based therapies will most likely require careful patient selection.

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.

MicroRNA-33a functions as a bone metastasis suppressor in lung cancer by targeting parathyroid hormone related protein

BACKGROUND

Bone is a common site of metastasis for lung cancer, and is associated with significant morbidity and a dismal prognosis. MicroRNAs (miRNAs) are increasingly implicated in regulating the progression of malignancies.

METHODS

The efficacy of miR-33a or anti-miR-33a plasmid was assessed by Real-time PCR. Luciferase assays were using One-Glo Luciferase Assay System. Measurement of secreted factors was determined by ELISA kit.

RESULTS

We have found that miR-33a, which is downregulated in lung cancer cells, directly targets PTHrP (parathyroid hormone-related protein), a potent stimulator of osteoclastic bone resorption, leading to decreased osteolytic bone metastasis. We also found that miR-33a levels are inversely correlated with PTHrP expression between human normal bronchial cell line and lung cancer cell lines. The reintroduction of miR-33a reduces the stimulatory effect of A549 on the production of osteoclastogenesis activator RANKL (receptor activator of nuclear factor kappa-B ligand) and M-CSF (macrophage colony-stimulating factor) on osteoblasts, while the expression of PTHrP is decreased in A549 cells. miR-33a overexpression also reduces the inhibitory activity of A549 on the production of OPG (osteoprotegerin), an osteoclastogenesis inhibitor. In addition, miR-33a-mediated PTHrP downregulation results in decreased IL-8 secretion in A549, which contributes to decreased lung cancer-mediated osteoclast differentiation and bone resorption.

CONCLUSIONS

These findings have led us to conclude that miR-33a may be a potent tumor suppressor, which inhibits direct and indirect osteoclastogenesis through repression of PTHrP.

GENERAL SIGNIFICANCE

miR-33a may even predict a poor prognosis for lung cancer patients.

Co-evolution of breast-to-brain metastasis and neural progenitor cells

Brain colonization by metastatic tumor cells offers a unique opportunity to investigate microenvironmental influences on the neoplastic process. The bi-directional interplay of breast cancer cells (mesodermal origin) and brain cells (neuroectodermal origin) is poorly understood and rarely investigated. In our patients undergoing neurosurgical resection of breast-to-brain metastases, specimens from the tumor/brain interface exhibited increased active gliosis as previously described. In addition, our histological characterization revealed infiltration of neural progenitor cells (NPCs) both outside and inside the tumor margin, leading us to investigate the cellular and molecular interactions between NPCs and metastases. Since signaling by the TGF-β superfamily is involved in both developmental neurobiology and breast cancer pathogenesis, we examined the role of these proteins in the context of brain metastases. The brain-metastatic breast cancer cell line MDA-MB-231Br (231Br) expressed BMP-2 at significantly higher levels compared to its matched primary breast cancer cell line MDA-MB-231 (231). Co-culturing was used to examine bi-directional cellular effects and the relevance of BMP-2 overexpression. When co-cultured with NPCs, 231 (primary) tumor cells failed to proliferate over 15 days. However, 231Br (brain metastatic) tumor cells co-cultured with NPCs escaped growth inhibition after day 5 and proliferated, occurring in parallel with NPC differentiation into astrocytes. Using shRNA and gene knock-in, we then demonstrated BMP-2 secreted by 231Br cells mediated NPC differentiation into astrocytes and concomitant tumor cell proliferation in vitro. In xenografts, overexpression of BMP-2 in primary breast cancer cells significantly enhanced their ability to engraft and colonize the brain, thereby creating a metastatic phenotype. Conversely, BMP-2 knockdown in metastatic breast cancer cells significantly diminished engraftment and colonization. The results suggest metastatic tumor cells create a permissive neural niche by steering NPC differentiation toward astrocytes through paracrine BMP-2 signaling.

Breast tumor-associated osteoblast-derived CXCL5 increases cancer progression by ERK/MSK1/Elk-1/snail signaling pathway

The skeleton is the most common metastatic site for breast cancer, with bone metastasis causing pain as well as risk of pathological fractures. Interaction between tumors and the bone microenvironment creates a vicious cycle that accelerates both bone destruction and cancer progression. This study is the first to analyze the soluble factors secreted by breast tumor-associated osteoblasts (TAOBs), which are responsible for promoting cancer progression. The addition of CXCL5 (chemokine (C-X-C motif) ligand 5), present in large amounts in TAOB-condition medium (TAOB-CM), mimicked the inductive effect of TAOB-CM on breast cancer epithelial-mesenchymal transition, migration and invasion. In contrast, inhibition of CXCL5 in OBs decreased TAOB-mediated cancer progression. Inducement of MCF-7 and MDA-MB-231 cancer progression by TAOB-derived CXCL5 is associated with increased Raf/MEK/ERK activation, and mitogen- and stress-activated protein kinase 1 (MSK1) and Elk-1 phosphorylation, as well as Snail upregulation. Activation of Elk-1 facilitates recruitment of phosphorylated MSK1, which in turn enhances histone H3 acetylation and phosphorylation (serine 10) of Snail promoter, resulting in Snail enhancement and E-cadherin downregulation. Moreover, mice treated with anti-CXCL5 antibodies showed decreased metastasis of 4T1 breast cancer cells. Our study suggests that inhibition of CXCL5-mediated ERK/Snail signaling is an attractive therapeutic target for treating metastases in breast cancer patients.

Behaviour of mesenchymal stem cells from bone marrow of untreated advanced breast and lung cancer patients without bone osteolytic metastasis

Tumour cells can find in bone marrow (BM) a niche rich in growth factors and cytokines that promote their self-renewal, proliferation and survival. In turn, tumour cells affect the homeostasis of the BM and bone, as well as the balance among haematopoiesis, osteogenesis, osteoclastogenesis and bone-resorption. As a result, growth and survival factors normally sequestered in the bone matrix are released, favouring tumour development. Mesenchymal stem cells (MSCs) from BM can become tumour-associated fibroblasts, have immunosuppressive function, and facilitate metastasis by epithelial-to-mesenchymal transition. Moreover, MSCs generate osteoblasts and osteocytes and regulate osteoclastogenesis. Therefore, MSCs can play an important pro-tumorigenic role in the formation of a microenvironment that promotes BM and bone metastasis. In this study we showed that BM MSCs from untreated advanced breast and lung cancer patients, without bone metastasis, had low osteogenic and adipogenic differentiation capacity compared to that of healthy volunteers. In contrast, chondrogenic differentiation was increased. Moreover, MSCs from patients had lower expression of CD146. Finally, our data showed higher levels of Dkk-1 in peripheral blood plasma from patients compared with healthy volunteers. Because no patient had any bone disorder by the time of the study we propose that the primary tumour altered the plasticity of MSCs. As over 70 % of advanced breast cancer patients and 30-40 % of lung cancer patients will develop osteolytic bone metastasis for which there is no total cure, our findings could possibly be used as predictive tools indicating the first signs of future bone disease. In addition, as the MSCs present in the BM of these patients may not be able to regenerate bone after the tumour cells invasion into BM/bone, it is possible that they promote the cycle between tumour cell growth and bone destruction.

Runx2 mediates epigenetic silencing of the bone morphogenetic protein-3B (BMP-3B/GDF10) in lung cancer cells

Background

The Runt-related transcription factor Runx2 is essential for bone development but is also implicated in progression of several cancers of breast, prostate and bone, where it activates cancer-related genes and promotes invasive properties. The transforming growth factor β (TGF-β) family member bone morphogenetic protein-3B (BMP-3B/GDF10) is regarded as a tumor growth inhibitor and a gene silenced in lung cancers; however the regulatory mechanisms leading to its silencing have not been identified.

Results

Here we show that Runx2 is highly expressed in lung cancer cells and downregulates BMP-3B. This inverse relationship between Runx2 and BMP-3B expression is further supported by increased expression of BMP-3B in mesenchymal cells from Runx2 deficient mice. The ectopic expression of Runx2, but not DNA binding mutant Runx2, in normal lung fibroblast cells and lung cancer cells resulted in suppression of BMP-3B levels. The chromatin immunoprecipitation studies identified that the mechanism of Runx2-mediated suppression of BMP-3B is due to the recruitment of Runx2 and histone H3K9-specific methyltransferase Suv39h1 to BMP-3B proximal promoter and a concomitant increase in histone methylation (H3K9) status. The knockdown of Runx2 in H1299 cells resulted in decreased histone H3K9 methylation on BMP-3B promoter and increased BMP-3B expression levels. Furthermore, co-immunoprecipitation studies showed a direct interaction of Runx2 and Suv39h1 proteins. Phenotypically, Runx2 overexpression in H1299 cells increased wound healing response to TGFβ treatment.

Conclusions

Our studies identified BMP-3B as a new Runx2 target gene and revealed a novel function of Runx2 in silencing of BMP-3B in lung cancers. Our results suggest that Runx2 is a potential therapeutic target to block tumor suppressor gene silencing in lung cancer cells.