Inhibitory effects of megakaryocytic cells in prostate cancer skeletal metastasis

Prostate cancer cells commonly spread through the circulation, but few successfully generate metastatic foci in bone. Osteoclastic cellular activity has been proposed as an initiating event for skeletal metastasis. Megakaryocytes (MKs) inhibit osteoclastogenesis, which could have an impact on tumor establishment in bone. Given the location of mature MKs at vascular sinusoids, they may be the first cells to physically encounter cancer cells as they enter the bone marrow. Identification of the interaction between MKs and prostate cancer cells was the focus of this study. K562 (human MK precursors) and primary MKs derived from mouse bone marrow hematopoietic precursor cells potently suppressed prostate carcinoma PC-3 cells in coculture. The inhibitory effects were specific to prostate carcinoma cells and were enhanced by direct cell-cell contact. Flow cytometry for propidium iodide (PI) and annexin V supported a proapoptotic role for K562 cells in limiting PC-3 cells. Gene expression analysis revealed reduced mRNA levels for cyclin D1, whereas mRNA levels of apoptosis-associated specklike protein containing a CARD (ASC) and death-associated protein kinase 1 (DAPK1) were increased in PC-3 cells after coculture with K562 cells. Recombinant thrombopoietin (TPO) was used to expand MKs in the marrow and resulted in decreased skeletal lesion development after intracardiac tumor inoculation. These novel findings suggest a potent inhibitory role of MKs in prostate carcinoma cell growth in vitro and in vivo. This new finding, of an interaction of metastatic tumors and hematopoietic cells during tumor colonization in bone, ultimately will lead to improved therapeutic interventions for prostate cancer patients. © 2011 American Society for Bone and Mineral Research.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78486/1/204_ftp.pd

Life-Threatening Anaphylactoid Reaction in an Acute Ischemic Stroke Patient With Intravenous rt-PA Thrombolysis, Followed by Successful Intra-Arterial Thrombolysis

An anaphylactoid reaction to recombinant tissue plasminogen activator (rt-PA) is an uncommon but fatal complication. A 39-year-old man was admitted within 1 hour of the onset of a right hemispheric stroke. He was not taking any specific medication, including angiotensin-converting enzyme (ACE) inhibitors. A systemic anaphylactoid reaction developed immediately after rt-PA infusion. However, the symptoms were improved after treatment with a steroid and antihistamine. Subsequent intra-arterial thrombolytic therapy resulted in complete recanalization and clinical improvement. To our knowledge, this is the first report of a life-threatening anaphylactoid reaction after rt-PA treatment followed by successful intra-arterial thrombolytic therapy in a patient who had not taken an ACE inhibitor

The role of SRC family kinase activation in prostate cancer growth and lymph node metastasis

Aberrant expression and/or activation of Src Family of non-receptor protein tyrosine kinases (SFKs) occur frequently during progressive stages of multiple types of human malignancies, including prostate cancer. Two SFKs, Src and Lyn, are expressed and implicated in prostate cancer progression. Work in this dissertation investigated the specific roles of Src and Lyn in the prostate tumor progression, and the effects of SFK inhibition on prostate tumor growth and lymph node metastasis in pre-clinical mouse models. Firstly, using a pharmacological inhibitor of SFKs in clinical trials, dasatinib, I demonstrated that SFK inhibition affects both cellular migration and proliferation in vitro. Systemic administration of dasatinib reduced primary tumor growth, as well as development of lymph node metastases, in both androgen-sensitive and -resistant orthotopic prostate cancer mouse models. Immunohistochemical analysis of the primary tumors revealed that dasatinib treatment decreased SFK phosphorylation but not expression, resulting in decreased cellular proliferation and increased apoptosis. For this analysis of immunohistochemical stained tissues, I developed a novel method of quantifying immunohistochemical stain intensity that greatly reduced the inherent bias in analyzing staining intensity. To determine if Src and Lyn played overlapping or distinct roles in prostate cancer tumor growth and progression, Src expression alone was inhibited by small-interfering RNA. The resulting stable cell lines were decreased in migration, but not substantially affected in proliferation rates. In contrast, an analogous strategy targeting Lyn led to stable cell lines in which proliferation rates were significantly reduced. Lastly, I tested the efficacy of a novel SFK inhibitor (KX2-391) targeting peptide substrate-binding domain, on prostate cancer growth and lymph node metastasis in vivo. I demonstrated that KX2-391 has similar effects as dasatinib, an ATP-competitive small molecular inhibitor, on both the primary tumor growth and development of lymph node metastasis in vivo, work that contributed to the first-in-man Phase I clinical trial of KX2-391. In summary, studies in this dissertation provide the first demonstration that Src and Lyn activities affect different cellular functions required for prostate tumor growth and metastasis, and SFK inhibitors effectively reduce primary tumor growth and lymph node metastasis. Therefore, I conclude that SFKs are promising therapeutic targets for treatment of human prostate cancer

Osteoblasts Are the Centerpiece of the Metastatic Bone Microenvironment

The tumor microenvironment is comprised of diverse stromal cell populations in addition to tumor cells. Increasing evidence now clearly supports the role of microenvironment stromal cells in tumor progression and metastasis, yet the regulatory mechanisms and interactions among tumor and stromal cells remain to be elucidated. Bone metastasis is the major problem in many types of human malignancies including prostate, breast and lung cancers, and the biological basis of bone metastasis let alone curative approaches are largely undetermined. Among the many types of stromal cells in bone, osteoblasts are shown to be an important player. In this regard, osteoblasts are a key target cell type in the development of bone metastasis, but there are currently no drugs or therapeutic approaches are available that specifically target osteoblasts. This review paper summarizes the current knowledge on osteoblasts in the metastatic tumor microenvironment, aiming to provide clues and directions for future research endeavor

Magnetically separable Pd catalyst for highly selective epoxide hydrogenolysis under mild conditions

A magnetically separable palladium catalyst was synthesized simply through a sol-gel process incorporating palladium nanoparticles and superparamagnetic iron oxide nanoparticles in aluminum oxyhydroxide matrix, which is highly active and selective for epoxide hydrogenolysis at room temperature under 1 atm H-2. The catalyst was recycled for 25 times without loss of the activityclose323

Rhodium and iridium nanoparticles entrapped in aluminum oxyhydroxide nanofibers: Catalysts for hydrogenations of arenes and ketones at room temperature with hydrogen balloon

The recyclable metal nanoparticle catalysts, rhodium in aluminum oxyhydroxide [Rh/AlO(OH)] and iridium in aluminum oxyhydroxide [Ir/AlO(OH)], were simply prepared from readily available reagents. The catalysts showed high activities in the hydrogenation of various arenes and ketones under mild conditions. Selective hydrogenation was possible for bicyclic and tricyclic arenes in high yields. The catalysts were active at room temperature even with a hydrogen balloon. Also, the catalysts showed high turnover frequency (TOF) values under solventless conditions at 75 degrees C under 4 atm hydrogen pressure: ca. 1700 h(-1) in the hydrogenation of benzene. Furthermore, Rh/AlO(OH) can be reused for at least 10 times without activity loss. The catalysts were characterized by the transmission electron microscopy (TEM), powder X-ray diffraction (XRD), inductively coupled plasma (ICP), energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption and hydrogen chemisorption experiments. The sizes of rhodium and iridium particles were estimated to be 3-4 nm and 2-3 nm, respectively. Aluminum oxyhydroxide nanofibers of these catalysts have surface areas of 500-600 m(2)g(-1)close50575

Mobilization of monocytic myeloid-derived suppressor cells is regulated by PTH1R activation in bone marrow stromal cells

Abstract Myeloid-derived suppressor cells (MDSCs) are bone marrow (BM)-derived immunosuppressive cells in the tumor microenvironment, but the mechanism of MDSC mobilization from the BM remains unclear. We investigated how BM stromal cell activation by PTH1R contributes to MDSC mobilization. PTH1R activation by parathyroid hormone (PTH) or PTH-related peptide (PTHrP), a tumor-derived counterpart, mobilized monocytic (M-) MDSCs from murine BM without increasing immunosuppressive activity. In vitro cell-binding assays demonstrated that α4β1 integrin and vascular cell adhesion molecule (VCAM)-1, expressed on M-MDSCs and osteoblasts, respectively, are key to M-MDSC binding to osteoblasts. Upon PTH1R activation, osteoblasts express VEGF-A and IL6, leading to Src family kinase phosphorylation in M-MDSCs. Src inhibitors suppressed PTHrP-induced MDSC mobilization, and Src activation in M-MDSCs upregulated two proteases, ADAM-17 and MMP7, leading to VCAM1 shedding and subsequent disruption of M-MDSC tethering to osteoblasts. Collectively, our data provide the molecular mechanism of M-MDSC mobilization in the bones of tumor hosts

Targeting the Hepatocyte Growth Factor and c-Met Signaling Axis in Bone Metastases

Bone metastasis is the terminal stage disease of prostate, breast, renal, and lung cancers, and currently no therapeutic approach effectively cures or prevents its progression to bone metastasis. One of the hurdles to the development of new drugs for bone metastasis is the complexity and heterogeneity of the cellular components in the metastatic bone microenvironment. For example, bone cells, including osteoblasts, osteoclasts, and osteocytes, and the bone marrow cells of diverse hematopoietic lineages interact with each other via numerous cytokines and receptors. c-Met tyrosine kinase receptor and its sole ligand hepatocyte growth factor (HGF) are enriched in the bone microenvironment, and their expression correlates with the progression of bone metastasis. However, no drugs or antibodies targeting the c-Met/HGF signaling axis are currently available in bone metastatic patients. This significant discrepancy should be overcome by further investigation of the roles and regulation of c-Met and HGF in the metastatic bone microenvironment. This review paper summarizes the key findings of c-Met and HGF in the development of novel therapeutic approaches for bone metastasis

Liposome-Encapsulated Bacillus Calmette–Guérin Cell Wall Skeleton Enhances Antitumor Efficiency for Bladder Cancer In Vitro and In Vivo via Induction of AMP-Activated Protein Kinase

The Mycobacterium Bacillus Calmette-Guérin cell wall skeleton (BCG-CWS), the main immune active center of BCG, is a potent candidate non-infectious immunotherapeutic drug and an alternative to live BCG for use against urothelial carcinoma. However, its application in anticancer therapy is limited, as BCG-CWS tends to aggregate in both aqueous and non-aqueous solvents. To improve the internalization of BCG-CWS into bladder cancer cells without aggregation, BCG-CWS was nanoparticulated at a 180 nm size in methylene chloride and subsequently encapsulated with conventional liposomes (CWS-Nano-CL) using an emulsified lipid (LEEL) method. In vitro cell proliferation assays showed that CWS-Nano-CL was more effective at suppressing bladder cancer cell growth compared to nonenveloped BCG-CWS. In an orthotopic implantation model of luciferase-tagged MBT2 bladder cancer cells, encapsulated BCG-CWS nanoparticles could enhance the delivery of BCG-CWS into the bladder and suppress tumor growth. Treatment with CWS-Nano-CL induced the inhibition of the mammalian target of rapamycin (mTOR) pathway and the activation of AMP-activated protein kinase (AMPK) phosphorylation, leading to apoptosis, both in vitro and in vivo. Furthermore, the antitumor activity of CWS-Nano-CL was mediated predominantly by reactive oxygen species (ROS) generation and AMPK activation, which induced endoplasmic reticulum (ER) stress, followed by c-Jun N-terminal kinase (JNK) signaling-mediated apoptosis. Therefore, our data suggest that the intravesical instillation of liposome-encapsulated BCG-CWS nanoparticles can facilitate BCG-CW cellular endocytosis and provide a promising drug-delivery system as a therapeutic strategy for BCG-mediated bladder cancer treatment