Hypercalcemia in prostate cancer with positive neuron-specific enolase stain

Hypercalcemia is a common complication of malignant diseases with or without bone metastasis. Hypercalcemia in prostate cancer is rarely seen. The exact mechanism of prostate cancer-related hypercalcemia is still uncertain. Secretion of parathyroid hormone-related peptides (PTH-rP) is thought to be one of the possible mechanisms. We reported a rare case of prostate cancer with hypercalcemia (13 mg/dL). Bone marrow biopsy showed metastatic adenocarcinoma. The cells were also positive for neuron-specific enolase, which is the specific marker for neuroendocrine cell. The finding suggested that the prostate cancer cell derived from the neuroendocrine cell, which might synthesize PTH-rP and be responsible for the observed hypercalcemia.     

DU145 human prostate cancer cells express functional receptor activator of NFkappaB: new insights in the prostate cancer bone metastasis process

Prostate cancer metastases to bone are observed in around 80% of prostate cancer patients and represent the most critical complication of advanced prostate cancer, frequently resulting in significant morbidity and mortality. As the underlying mechanisms are not fully characterized, understanding the biological mechanisms that govern prostate cancer metastases to bone at the molecular level should lead to the determination of new potential therapeutic targets. Receptor activator of NFkappaB ligand (RANKL)/RANK/Osteoprotegerin (OPG) are the key regulators of bone metabolism both in normal and pathological condition, including prostate cancer bone metastases. In the present study, we demonstrated that human prostate cancer cell lines, DU145 and PC3 express biologically functional RANK. Indeed, soluble human RANKL (shRANKL, 100 ng/ml) treatment induced ERK 1/2, p38 and IkappaB phosphorylations in these cells. shRANKL administration also promoted DU145 and PC3 prostate cancer cell invasion in vitro. Whereas human OPG (hOPG) administration alone (100 ng/ml) had no marked effect, combined association of both agents abolished the RANKL-induced DU145 cell invasion. As RANKL had no direct effect on DU145 cell proliferation, the observed effects were indeed related to RANKL-induced cell migration. DU145 human prostate cancer cells promoted osteoclastogenesis of osteoclast precursors generated from mouse bone marrow. Moreover, DU145 cells produced soluble factor(s) that up-regulate the proliferation of MC3T3-E1 pre-osteoblasts through the activation of the ERK 1/2 and STAT3 signal transduction pathways. This stimulation of pre-osteoblast proliferation resulted in an increased local RANKL expression that can activate both osteoclasts/osteoclast precursors and prostate cancer cells, thus facilitating prostate cancer metastasis development in bone. We confirm that RANKL is a factor that facilitates metastasis to bone by acting as an activator of both osteoclasts and RANK-positive prostate cancer cells in our model. Furthermore, the present study provides the evidence that blocking RANKL-RANK interaction offer new therapeutic approach not only at the level of bone resorbing cells, but also by interfering with RANK-positive prostate cancer cells in the prostate cancer bone metastasis development.     

Mechanisms governing bone metastasis in prostate cancer

Why does prostate cancer metastasize to bone? Why is there increased turnover of the bone matrix in the presence of prostate cancer? A recent autopsy study supports a traditional hypothesis that gross, anatomic patterns of blood flow influence the distribution of metastatic deposits. On the other hand, recent developments in animal models of prostate cancer bone metastasis have renewed interest in the traditional 'seed and soil' hypothesis: several studies point to specific biological interactions between prostate cancer cells and the bone microenvironment that can explain the tendency of prostate cancer cells to colonize bone and grow into clinically relevant metastatic deposits. Some studies implicate mechanisms including chemoattraction and enhanced adherence to bone endothelium. Additional data suggest that prostate cancer cells are 'osteomimetic', that is, they take on the properties and behaviors of osteoblasts or osteoclasts upon arrival in bone. These activities lead to enhanced turnover of the bone matrix and may explain the propensity of prostate cancer to grow in bone. Finally, a series of studies have implicated other molecular markers as distinguishing characteristics of bone-metastatic prostate cancer tissue.     

Bone loss in patients with breast or prostate cancer

Cancers of the breast and prostate are very common in the general population, with breast cancer accounting worldwide for 23% of cancer cases in women and prostate cancer accounting for 12% of cases in men. During the past decade, the survival rates of patients with estrogen-dependent breast cancer and testoster-one-dependent prostate cancer have improved. This improvement has been possible thanks to the introduction of hormone treatments that suppress the synthesis or antagonize the actions of gonadal steroids. However, estrogen and testosterone deficiencies are associated with excessive bone resorption that translates into damage of the bone microarchitecture, loss of bone mineral density, and predisposition to osteoporosis and fractures. Herein, we review the mechanisms of bone loss in breast and prostate cancer survivors, their clinical implications, and different available therapeutic modalities that may help to correct the damage of bone and prevent the development of fractures.     

Intraosseous growth of human prostate cancer in implanted adult human bone: relationship of prostate cancer cells to osteoclasts in osteoblastic metastatic lesions

BACKGROUND: More than 80% of patients with advanced prostate cancer have skeletal involvement, but the biology of bone metastasis is poorly understood. This study investigated the in vivo formation and progression of bone metastases under conditions that resembled the human bone environment as closely as possible. METHODS: Adult human bone fragments were implanted subcutaneously into 120 male NOD/SCID mice. Four weeks later, 1 x 10(7) LNCaP prostate cancer cells or phosphate-buffered saline were injected intravenously into 80 or 40 mice, respectively. The implanted bone fragments were removed from 20 to 10 mice in each group at 2, 4, 6, and 8 weeks after injection. RESULTS: LNCaP colonized the bone marrow blood vessels within 2 weeks, and then gradually expanded into the entire medullary cavity. An osteoblastic response often occurred at the edges of metastatic foci (intertrabecular bone metaplasia). In addition, new bone formation was observed adjacent to mature lamellar bone (appositional bone formation). These two processes appeared to occur through different mechanisms, but might similarly cause osteosclerosis. Osteoclasts showed a marked increase in numbers at sites of early tumor invasion, whereas few osteoclasts were observed at sites where tumor invasion was complete. CONCLUSIONS: The predominance of osteoblastic change with resorption may lead to bone remodeling in metastatic lesions, and osteoclasts may play an important role in bone metastasis from prostate cancer.     

Cell adhesion and chemotaxis in prostate cancer metastasis to bone: a minireview

Bone metastasis is a common phenomenon in patients with advanced prostate cancer. The molecular and cellular mechanisms involved in this process are not well understood. Past reviews on this subject primarily focused on prostate tumor growth in the bone marrow and the effects this growth has on bone homeostasis (ie osteoblastic and osteolytic). Cell chemotaxis and adhesion are also important for site-specific metastasis. In this review we have focused on chemotactic and cell adhesion molecules potentially involved in prostate cancer metastasis to bone. In addition, recently developed animal models for prostate cancer metastasis to bone are discussed. Prostate Cancer and Prostatic Diseases (2000) 3, 6-12     

Inhibition of prostate cancer growth by estramustine and colchicine

Hormone-refractory prostate cancer continues to be associated with a very poor prognosis. Agents that inhibit microtubule function have been found to be cytotoxic to prostate cancer cells in preclinical and clinical settings. It was the aim of this study to assess the activity of estramustine and colchicine, two microtubule inhibitors, in hormone-refractory prostate cancer. In clinically achievable concentrations, the combination of estramustine and colchicine was cytotoxic to both the Dunning rat prostate adenocarcinoma cell line MAT-LyLu (MLL) and human prostate cancer cells (PC-3). Microtubule function was assessed in vitro to evaluate possible mechanisms of action. In motility and cell cycle analysis assays, estramustine and colchicine inhibited cellular motility but not cell cycle transit. In vivo, these two agents both inhibited the growth of implanted Dunning rat prostate adenocarcinoma MLL cells but did not appear to have additive effects. The use of oral colchicine in the treatment of hormone-refractory prostate cancer requires further investigation.     

Future perspectives of prostate cancer therapy

We summarize several recent laboratory advances to tackle the problem of tumor-stroma-immune cell microenvironment interaction with the hope of developing and advancing new concepts and therapeutic strategies for prostate cancer therapy by improving bone and soft tissue metastases in prostate cancer patients. Given the emerging enthusiasm for immunotherapy in prostate cancer due to (I) improved understanding of the role of immune cells in the tumor microenvironment, (II) approval by the FDA of an immunotherapeutic drug to treat prostate cancer, and (III) recognition of immunotherapy as a novel approach to treat solid tumors by the Nobel Prize Committee (for discovery of dendritic cells that are used in immunotherapy), the field of tumor immunology is poised for growth in the next decade with the hope of developing new immunomodulatory drugs which will compliment and perhaps eventually replace traditional chemotherapeutic drugs. In this article, we provide a timely review of recent advances in the field of immunotherapy for prostate cancer, lessons learned from successes and failures, the contributory factors in the tumor microenvironment that could be rendered hostile to cancer cells, an exciting area of future research.     

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.     

Molecular insights into prostate cancer progression: the missing link of tumor microenvironment

PURPOSE: Tumor cell genotype and phenotype have been considered the only determinants supporting cancer growth and metastasis. This review focuses on the published literature that suggests that tumor-microenvironment interaction has a decisive role in controlling local cancer growth, invasion and distant metastasis. As this review shows, genetic alterations in prostate cancer cells alone are not enough to confer metastatic status without a supporting tumor microenvironment. Effective therapeutic targeting requires a deeper understanding of the interplay between tumor and stroma. Approaches co-targeting tumor and stroma already show promise over the conventional targeting of tumor cells alone in preventing prostate cancer progression and eradicating preexisting or newly developed prostate cancers in bone and visceral organs. MATERIALS AND METHODS: A literature survey using the MEDLINE database was performed in basic and clinical publications relevant to tumor-host microenvironment interaction. Information pertinent to the biology and therapy of prostate cancer local growth and distant metastases was specifically emphasized. RESULTS: Tumor associated stroma actively fuel the progression of prostate cancer from localized growth to the invasion of surrounding tissues, and the development of distant bone and visceral organ metastasis. In concert with this progression tumor cells recovered from metastatic sites could represent a subpopulation of preexisting tumor cells or could be a newly acquired variant subsequent to tumor-stromal interaction. Experimental data from our laboratory and others suggest that permanent genetic and phenotypic changes occur in prostate cancer cells after 3-dimensional co-culture in vitro or when co-inoculated and grown with inductive stromal cells in vivo. These results support the idea that newly acquired variants are the dominant mechanism of prostate cancer progression. Intercellular communication between prostate cancer cells and organ specific stroma, including prostate and marrow stroma, could involve diffusible soluble and solid matrix molecules as mediators, leading to the development of metastasis. This presents a new opportunity for therapeutic targeting for the treatment of benign and malignant growth of the prostate glands. This review summarizes specific research implicating tumor-microenvironment interaction as the molecular basis of cancer progression, providing a rationale for targeting tumor and the tumor associated microenvironment in the management of androgen independent and bone metastatic prostate cancer progression in patients. CONCLUSIONS: Cancer is not a single cell disease. Aberrant cancer cells and their interactive microenvironment are needed for prostate cancer to progress to androgen independence and distant metastasis. It is highly plausible that newly evolved prostate cancer cell clones dominate cancer metastasis after cell-cell and cell-matrix interaction with the host microenvironment, rather than the selection or expansion of a preexisting prostate cancer cell clone(s). Based on this premise potential molecular targets in the microenvironment are especially emphasized. Further elucidation of the molecular mechanisms underlying tumor-stromal interaction may yield improved medical treatments for prostate cancer growth and metastasis.     

Telomerase activity in disseminated prostate cancer cells

OBJECTIVE: To analyse telomerase activity in disseminated prostate cancer cells isolated from bone marrow aspirates taken from men with localized prostate cancer before radical prostatectomy (RP). PATIENTS AND METHODS: Disseminated epithelial prostate cancer cells were isolated from bone marrow aspirates from 69 men with localized prostate cancer before RP, by magnetic column-chromatography enrichment, followed by isolation of fluorescently labelled epithelial cells by micropipetting. We used pools of 10 non-epithelial bone marrow cells after tumour cell enrichment as control samples. These pure cell pools were tested for the presence of telomerase activity. RESULTS: In all, 49 of the patient samples contained disseminated prostate cancer cells. Homogeneous pools of 10 cells were obtained from 35 of these; 49% of the 35 specimens showed telomerase activity, whereas all five control samples did not. Telomerase activity in the 35 samples was not significantly associated with Gleason score, preoperative prostate-specific antigen level, tumour stage, or surgical margin status. Follow-up is continuing to assess an association with disease recurrence. CONCLUSION: This work shows the feasibility of isolating disseminated cancer cells for analysing individual or pooled cells. Compared to tissue staining, where telomerase is detected in 80-90% of samples, we found lower rates of telomerase activity in the disseminated tumour cells (49%). Telomerase-negative cells might provide information about cell dormancy, as telomerase is a marker of cell proliferation in immortal and cancer cells. Telomerase-positive cells might predict early disease recurrence, but a longer follow-up is needed to test this possibility.     

Stem cells in prostate and prostate cancer development

Most cancers comprise a heterogenous population of cells with marked differences in their potential to proliferate as well as the ability to reconstitute the tumor upon transplantation. Cancer stem cells are a minor population of tumor cells that possess the stem cell property of self-renewal. Dysregulation of stem cell self-renewal is a likely requirement for the development of cancer. Cell signaling pathways shared by stem cells and cancer cells lend further evidence for a possible link between these 2 populations of cells. Study of the differentiation pathways of normal and abnormal prostate growth has led to the development of a stem cell model for prostate cancer. The basal layer of the normal prostate is believed to be populated by prostate epithelial stem cells and a population of transit-amplifying cells intermediate in differentiation to the stem and fully differentiated cells. There is recent evidence suggesting that prostate cancer occurs from malignant transformation of stem/progenitor cells, thereby resisting apoptosis and spawning proliferation. This new model for prostate cancer will have significant ramifications for the way this disease is studied and treated. Furthermore, through targeting the prostate cancer stem cell and its dysregulated self-renewal, therapies for treatment of prostate cancer are likely to improve.     

间充质干细胞在小鼠体内可以向前列腺癌组织募集促进前列腺癌的生长

目的探索间充质干细胞在小鼠体内与前列腺癌组织生长的关系,以期为前列腺癌的治疗探索新的靶点。方法野生型C57BL/6小鼠经致死剂量照射后,接受EGFP绿色荧光转基因C57BL/6小鼠的MSCs以及野生型小鼠全骨髓细胞的混合移植。1月后在骨髓移植成功的小鼠身上建立前列腺癌RM-1细胞皮下移植瘤模型,检测前列腺癌肿瘤的生长情况。同时以荧光显微镜显像技术及流式细胞仪技术观察、检测MSCs在小鼠前列腺癌组织中的表达情况。结果皮下接种RM-1前列腺癌细胞后,给予小鼠尾静脉注射MSCs的实验组肿瘤的生长速度要快于注射生理盐水的对照组,肿瘤重量分别为(3.730±0.632)g、(2.019±0.254)g(P0.05);无论是骨髓移植后内源性的MSCs还是直接尾静脉注射的外源性MSCs都可以在前列腺癌组织中检测到。结论内源性以及外源性的MSCs都可以向前列腺癌组织趋化募集,并促进前列腺癌的生长。     

The bisphosphonate YM529 inhibits osteoblastic bone tumor proliferation of prostate cancer

BACKGROUND: In men, prostate cancer frequently metastasizes to the bones, where it forms osteoblastic lesions with an osteolytic element that cause pain. However, the role of osteoclastogenesis in bone metastasis of human prostate cancer is unknown. Bisphosphonates are already known to be beneficical for treating osteolytic bone metastases, so we employed a model of osteoblastic bone tumor of human prostate cancer to investigate whether a new bisphosphonate (YM529: minodronate) could inhibit both the formation of bone tumors and the progression of established osteoblastic tumors. METHODS: Human prostate cancer cells (LNCaP) were injected into adult human bone implants in nonobese diabetic/severe combined immunodeficient mice, after which osteoblastic bone tumors developed. YM529 (1 microg/day) was administered subcutaneously every day for 2 weeks, starting either immediately or 2 weeks after implantation of the tumor cells, and the mice were sacrificed at 4 weeks after implantation. The bone tumors were examined histologically and the number of tartrate-resistant acid phosphatase-stained osteoclasts in each tumor focus was counted. RESULTS: Histomorphometric analysis revealed that YM529 markedly inhibited both the formation of bone tumors and the progression of established tumors, as well as markedly reducing the number of osteoclasts. CONCLUSIONS: YM529 reduced the tumor burden in bone by inhibiting both the formation of new lesions and the progression of existing tumors, suggesting that osteoclasts are involved in the formation of bone tumors by prostate cancer. Treatment with this bisphosphonate may potentially be beneficial for patients with bone metastases of prostate cancer.     

Bi-directional interactions of prostate cancer cells and bone marrow endothelial cells in three-dimensional culture

BACKGROUND: Prostate cancer preferentially metastasizes to bone, yet little is known about the cellular and molecular factors that support this growth. Endothelial cells are likely the initial contact for circulating prostate cells entering the bone microenvironment. METHODS: Using co-culture and conditioned media experiments, we studied cellular and molecular interactions of prostate cancer cells of varying aggressiveness (PC-3 and LNCaP) with bone marrow endothelial (HBME-1) cells in collagen gels. RESULTS: In co-culture, HBME-1 cells stimulated proliferation ( approximately 90% increase) and migration of the more aggressive PC-3 cell line, while having little effect on LNCaP cell proliferation or migration. Concomitantly, HBME-1 cell growth was inhibited by both PC-3 and LNCaP cells and their conditioned media. Additionally, HBME-1 cells underwent significant morphological changes in co-culture, forming large, branching, cord-like structures, which mimic angiogenesis. Prostate cancer cell conditioned media induced a similar effect on HBME-1 cells. In comparison, conditioned media from PC-3 cells also inhibited growth of non-bone marrow-derived endothelial cells, but did not affect their morphology. CONCLUSIONS: Significant bi-directional interactions, including secreted factors and direct cellular interactions, exist between bone marrow endothelial cells and highly metastatic prostate cancer cells, and may underlie the propensity for prostate cancer to metastasize to the bone.     

Overexpression of E-cadherin and beta-catenin proteins in metastatic prostate cancer cells in bone

BACKGROUND: The expression of E-cadherin in the intercellular adhesion of metastatic prostate cancer cells in bone, which is the most prevalent site of metastatic growth, remains elusive. METHODS: The aim of the study was to compare the concurrent membranous expression of E-cadherin and beta-catenin proteins, the state which is known to be associated with the cellular adhesion function of E-cadherin, in prostate biopsy tissue specimens by immunohistochemical staining method. The expression patterns of E-cadherin or beta-catenin were classified as homogeneous (most cells exhibiting positively), heterogeneous (a few scattered patches of cells with positivity) or negative. RESULTS: Benign prostate hyperplasia cells exhibited homogeneous expression of both E-cadherin and beta-catenin in 9 of 11 (82%), whereas the primary prostate cancer cells were homogeneously positive for both proteins only in 4 of 22 (18%) of the cases. The results are similar to those reported in literature. However, in contrast to the primary cancer, a significantly increased frequency of the metastatic prostate cancer cells in bone exhibited homogeneous expression of E-cadherin and beta-catenin in 12 of 17 (71%) of the cases. A statistically significant association was observed between the overexpression of both proteins and the metastatic prostate cancer cells in bone (Fisher's exact P < 0.001). CONCLUSIONS: The result of the study demonstrated for the first time that the membranous overexpression of E-cadherin and beta-catenin are significantly associated with the metastatic prostate cancer cells in bone and that the high frequency of expression suggest their involvement in the intercellular adhesion of the metastatic cells in bone.     

Fatty acids and prostate cancer: current status and future challenges

In this article the basic biology and function of fatty acids (FAs) will be reviewed. The literature relating to FAs and prostate cancer will be evaluated and possible mechanisms for the mode of action of FAs in the carcinogenesis and progression of prostate cancer will be discussed. In addition, the potential role for specific FAs in the treatment and prevention of prostate cancer will be assessed.     

Expression of bone morphogenetic protein messenger RNAs by normal rat and human prostate and prostate cancer cells

Human prostate cancer cells are known to produce several growth regulatory factors, including transforming growth factor β (TGFβ) and heparin-binding fibroblast growth factors (FGFs), which may play as-yet-undefined roles in prostate gland morphogenesis, as well as in prostate cancer cell behavior. Recently, a family of proteins in the extended TGFβ family, the bone morphogenetic proteins (BMPs), has been identified which stimulates bone formation in vivo, and in which, the proteins are likely involved in a variety of morphogenetic processes during embryogenesis. These powerful morphogenetic factors are capable of redirecting muscle mesenchyme cells to differentiate along the lines of bone tissue. We examined a number of well-characterized rat and human prostate cancer cell lines for the expression of BMP 2, 3, 4, and 6 messenger RNA. Poly(A + )-RNA was isolated from normal human and rat ventral prostate, from the rat prostate adenocarcinoma PAIII tumor and cultured cells derived from it, and from human prostate cancer cell lines PC-3, LNCaP, and DU-145. BMP mRNA levels were measured using BMP 2, 3, 4 and Vgr-1 (BMP 6) cDNA probes. Both normal and neoplastic prostate tissue expressed these BMP mRNAs, although the level of expression varied from tumor to tumor. Normal human prostate expressed BMP 4 mRNA predominantly, as did the human prostate cancers PC-3 and DU-145. PC-3 also expressed BMP 2 mRNA and BMP 3 mRNA in large amounts. Normal rat ventral prostate expressed all these BMP mRNAs, but the rat prostate adenocarcinoma PAIII expressed predominantly BMP 3 mRNA. The reason that different BMPs are expressed in varying amounts by these normal and neoplastic cells is unknown. However, if these BMPs are expressed in biologically active form, they could be responsible for important effects on normal prostate growth and morphogenesis, on neoplastic prostate cell behavior, and could even contribute to the capacity of prostatic cancer cells to stimulate new bone formation at metastatic tumor sites in bone. © 1994 Wiley-Liss, Inc.     

Granulocyte-macrophage colony-stimulating factor-transduced allogeneic cancer cellular immunotherapy: the GVAX vaccine for prostate cancer

New approaches to therapeutics of advanced prostate cancer are urgently needed. GVAX (granulocyte-macrophage colony-stimulating factor [GM-CSF] gene transduced irradiated prostate cancer vaccine cells) offers the possibility that "host versus prostate cancer" immune responses can be generated in prostate cancer patients. Critical components involve the dendritic cell loading of candidate prostate cancer lymph node metastasis and candidate bone metastasis antigens derived from irradiated prostate cancer whole cells. GM-CSF acts at the vaccination site to enhance activation dendritic cells and antigen presentation to both the B-cell and T-cell arms of the immune system. GVAX preclinically-in both rat and transgenic prostate cancer models-has antitumor activity which has informed early clinical trial designs. Clinical investigations reviewed in this report suggest that vaccination is safe and immune tolerance can be broken against prostate cancer. Multi-institutional phase III investigation is currently underway to evaluate the impact of allogeneic prostate GVAX cellular immunotherapy on time to progression and overall survival in hormone refractory prostate cancer.