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Kenneth J Pienta

Publications and source records attributed to Kenneth J Pienta.

At least 19 recordsLinked to original sources
PubMed2007

Expression and activation of alpha v beta 3 integrins by SDF-1/CXC12 increases the aggressiveness of prostate cancer cells.

BACKGROUND: Stromal cell-derived factor-1 (SDF-1 or CXCL12) and CXCR4 are key elements in the metastasis of prostate cancer cells to bone--but the mechanisms as to how it localizes to the marrow remains unclear. METHODS: Prostate cancer cell lines were stimulated with SDF-1 and evaluated for alterations in the expression of adhesion molecules using microarrays, FACs, and Western blotting to identify alpha(v)beta(3) receptors. Cell-cell adhesion and invasion assays were used to verify that activation of the receptor is responsive to SDF-1. RESULTS: We demonstrate that SDF-1 transiently regulates the number and affinity of alpha(v)beta(3) receptors by prostate cancer cells to enhance their metastatic behavior by increasing adhesiveness and invasiveness. SDF-1 transiently increased the expression of beta(3) receptor subunit and increased its phosphorylation in metastatic but not nonmetastatic cells. CONCLUSIONS: The transition from a locally invasive phenotype to a metastatic phenotype may be primed by the elevated expression of alpha(v)beta(3) receptors. Activation and increased expression of alpha(v)beta(3) within SDF-1-rich organs may participate in metastatic localization.

Bone Neoplasms↗
PubMed2007

A glycolytic mechanism regulating an angiogenic switch in prostate cancer.

The generation of an "angiogenic switch" is essential for tumor growth, yet its regulation is poorly understood. In this investigation, we explored the linkage between metastasis and angiogenesis through CXCL12/CXCR4 signaling. We found that CXCR4 regulates the expression and secretion of the glycolytic enzyme phosphoglycerate kinase 1 (PGK1). Overexpression of PGK1 reduced the secretion of vascular endothelial growth factor and interleukin-8 and increased the generation of angiostatin. At metastatic sites, however, high levels of CXCL12 signaling through CXCR4 reduced PGK1 expression, releasing the angiogenic response for metastastic growth. These data suggest that PGK1 is a critical downstream target of the chemokine axis and an important regulator of an "angiogenic switch" that is essential for tumor and metastatic growth.

Angiostatins↗
PubMed2006

Integrative molecular concept modeling of prostate cancer progression.

Despite efforts to profile prostate cancer, the genetic alterations and biological processes that correlate with the observed histological progression are unclear. Using laser-capture microdissection to isolate 101 cell populations, we have profiled prostate cancer progression from benign epithelium to metastatic disease. By analyzing expression signatures in the context of over 14,000 'molecular concepts', or sets of biologically connected genes, we generated an integrative model of progression. Molecular concepts that demarcate critical transitions in progression include protein biosynthesis, E26 transformation-specific (ETS) family transcriptional targets, androgen signaling and cell proliferation. Of note, relative to low-grade prostate cancer (Gleason pattern 3), high-grade cancer (Gleason pattern 4) shows an attenuated androgen signaling signature, similar to metastatic prostate cancer, which may reflect dedifferentiation and explain the clinical association of grade with prognosis. Taken together, these data show that analyzing gene expression signatures in the context of a compendium of molecular concepts is useful in understanding cancer biology.

Androgens↗
PubMed2006

Evolution of cooperation among tumor cells.

The evolution of cooperation has a well established theoretical framework based on game theory. This approach has made valuable contributions to a wide variety of disciplines, including political science, economics, and evolutionary biology. Existing cancer theory suggests that individual clones of cancer cells evolve independently from one another, acquiring all of the genetic traits or hallmarks necessary to form a malignant tumor. It is also now recognized that tumors are heterotypic, with cancer cells interacting with normal stromal cells within the tissue microenvironment, including endothelial, stromal, and nerve cells. This tumor cell-stromal cell interaction in itself is a form of commensalism, because it has been demonstrated that these nonmalignant cells support and even enable tumor growth. Here, we add to this theory by regarding tumor cells as game players whose interactions help to determine their Darwinian fitness. We marshal evidence that tumor cells overcome certain host defenses by means of diffusible products. Our original contribution is to raise the possibility that two nearby cells can protect each other from a set of host defenses that neither could survive alone. Cooperation can evolve as by-product mutualism among genetically diverse tumor cells. Our hypothesis supplements, but does not supplant, the traditional view of carcinogenesis in which one clonal population of cells develops all of the necessary genetic traits independently to form a tumor. Cooperation through the sharing of diffusible products raises new questions about tumorigenesis and has implications for understanding observed phenomena, designing new experiments, and developing new therapeutic approaches.

Biological Evolution↗
PubMed2006

Modeling somatic evolution in tumorigenesis.

Tumorigenesis in humans is thought to be a multistep process where certain mutations confer a selective advantage, allowing lineages derived from the mutated cell to outcompete other cells. Although molecular cell biology has substantially advanced cancer research, our understanding of the evolutionary dynamics that govern tumorigenesis is limited. This paper analyzes the computational implications of cancer progression presented by Hanahan and Weinberg in The Hallmarks of Cancer. We model the complexities of tumor progression as a small set of underlying rules that govern the transformation of normal cells to tumor cells. The rules are implemented in a stochastic multistep model. The model predicts that (i) early-onset cancers proceed through a different sequence of mutation acquisition than late-onset cancers; (ii) tumor heterogeneity varies with acquisition of genetic instability, mutation pathway, and selective pressures during tumorigenesis; (iii) there exists an optimal initial telomere length which lowers cancer incidence and raises time of cancer onset; and (iv) the ability to initiate angiogenesis is an important stage-setting mutation, which is often exploited by other cells. The model offers insight into how the sequence of acquired mutations affects the timing and cellular makeup of the resulting tumor and how the cellular-level population dynamics drive neoplastic evolution.

Cell Transformation, Neoplastic↗
PubMed2006

Dose escalation of oral vinorelbine in combination with estramustine in hormone-refractory adenocarcinoma of the prostate.

BACKGROUND: The primary objective of the current study was to identify the tolerable dose level of oral vinorelbine when given in combination with estramustine to men with hormone-refractory prostate cancer (HRPC). The secondary objectives were to describe the toxicities of the combined regimen in patients with HRPC and to estimate the efficacy of oral vinorelbine in combination with estramustine based on the prostate-specific antigen (PSA) response. METHODS: Thirty-three patients with HRPC were treated on a 28-day cycle with estramustine at a dose of 140 mg orally 3 times a day on Days 1-3 and 8-10. Vinorelbine was given orally on Days 2 and 9. The initial dose of vinorelbine was 50 mg/m2 and was escalated to 70 mg/m2 using the time-to-event continual reassessment method. RESULTS: Three of 17 patients experienced dose-limiting toxicity at the 70 mg/m2 dose level of oral vinorelbine. One patient experienced dose-limiting toxicity at a dose of 60 mg/m2 and no dose-limitig toxicities were reported at the 50 mg/m2 dose. The overall response rate by > or = 50% reduction in PSA was 17.2%, (95% confidence interval, 5.9-35.8%). CONCLUSIONS: Oral vinorelbine at doses of 70 mg/m2 may be safely combined with estramustine. The combination appears to have modest activity in men with advanced prostate cancer. The trial design employed the time-to-event continual reassessment method, which potentially allows for rapid accrual, a more complete assessment of toxicities, and a larger fraction of patients to be treated at an effective dose. More active regimens are needed to further evaluate the utility of this clinical trial design in patients with prostate cancer.

Adenocarcinoma↗
PubMed2006

GREB1 is a novel androgen-regulated gene required for prostate cancer growth.

BACKGROUND: Gene regulated in breast cancer 1 (GREB1) is a novel estrogen-regulated gene shown to play a pivotal role in hormone-stimulated breast cancer growth. GREB1 is expressed in the prostate and its putative promoter contains potential androgen receptor (AR) response elements. METHODS: We investigated the effects of androgens on GREB1 expression and its role in androgen-dependent prostate cancer growth. RESULTS: Real-time PCR demonstrated high level GREB1 expression in benign prostatic hypertrophy (BPH), localized prostate cancer (L-PCa), and hormone refractory prostate cancer (HR-PCa). Androgen treatment of AR-positive prostate cancer cells induced dose-dependent GREB1 expression, which was blocked by anti-androgens. AR binding to the GREB1 promoter was confirmed by chromatin immunoprecipitation (ChIP) assays. Suppression of GREB1 by RNA interference blocked androgen-stimulated LNCaP cell proliferation. CONCLUSIONS: GREB1 is expressed in proliferating prostatic tissue and prostate cancer, is regulated by androgens, and suppression of GREB1 blocks androgen-induced growth suggesting GREB1 may be critically involved in prostate cancer proliferation.

Androgens↗
PubMed2006

Phase II trial of oral uracil/tegafur plus leucovorin in patients with hormone-refractory prostate carcinoma.

BACKGROUND: The current study evaluated the efficacy of oral uracil/tegafur (UFT) and leucovorin (LV) in patients with hormone-refractory metastatic prostate carcinoma. METHODS: Twenty-eight patients with hormone-refractory metastatic carcinoma of the prostate who had undergone antiandrogen withdrawal and no more than 1 prior chemotherapy treatment were enrolled on a single-institution Phase II trial. Patients were treated with oral UFT at a dose of 300 mg/m2/d and oral LV at a dose of 90 mg/day for 28 days followed by 7 days off therapy on a 35-day cycle regimen. RESULTS: Twenty-six patients were evaluable for response and toxicity. There was no response by objective criteria in 9 patients with measurable disease. Four responses by prostate-specific antigen (PSA) criteria (i.e., PSA decrease by > 50%) were noted (15%) lasting a mean of 20.5 weeks. Therapy was generally well tolerated, with 2 patients developing Grade 4 toxicity (1 patient each with diarrhea and hand-foot syndrome) and 4 patients having significant Grade 3 toxicity (anemia, hyperbilirubinemia, and vomiting) (Toxicity was graded according to the National Cancer Institute Common Toxicity Criteria). Six patients had stable disease by clinical, laboratory, and radiologic criteria for an average of 5 cycles of treatment (25 wks). CONCLUSIONS: Although UFT and LV are generally well tolerated in the setting of hormone-refractory metastatic prostate carcinoma, the combination has a low level of activity. Its toxicity and activity is similar to that observed when intravenous 5-fluorouracil or capecitabine are given alone. It may be an option for further investigations in combination regimens.

Adenocarcinoma↗
PubMed2006

Simulating the hallmarks of cancer.

Cancer can be viewed as the loss of cooperative cell behaviors that normally facilitate multicellularity, including the formation of tissues and organs. Hanahan and Weinberg describe the phenotypic differences between healthy and cancerous cells in an article titled "The Hallmarks of Cancer" (Cell, 100, 57-70, 2000). Here the authors propose six phenotypic changes at the cellular level as the essential hallmarks of cancer. They investigate the dynamics and interactions of these hallmarks in a model known as CancerSim. They describe how CancerSim implements the hallmarks in an agent-based simulation which can help test the hypotheses put forth by Hanahan and Weinberg. Experiments with CancerSim are described that study the interactions of cell phenotype alterations, and in particular, the likely sequences of precancerous mutations, known as pathways. The experiments show that sequencing is an important factor in tumorigenesis, as some mutations have preconditions--they are selectively advantageous only in combination with other mutations. CancerSim enables a modeler to study the dynamics of a developing tumor and simulate how progression can be altered by tuning model parameters.

Apoptosis↗
PubMed2006

Inhibition of decay-accelerating factor (CD55) attenuates prostate cancer growth and survival in vivo.

Decay-accelerating factor (CD55) is a member of membrane-bound complement-regulatory proteins. CD55 expression correlates with poor survival in patients with colorectal cancer and has been implicated in the survival and tumorigenesis of blood-borne malignancies. Histologic analysis of clinical specimens from patients with advanced prostate cancer revealed an increase in CD55 expression in prostate tumor epithelial cells. CD55 was shown to be functionally active and to inhibit complement-mediated lysis in PC-3 and DU145 cells. The percentage of lysis was correlative with the CD55 expression profile observed in these prostate cancer cell lines. These data suggest that CD55 is an important regulator of prostate cancer cell survival. As a result, we have hypothesized that CD55 expression on prostate cancer cells promotes cell survival and contributes to the metastatic potential of prostate cancer cells. To determine the role of CD55 in prostate cancer tumorigenesis and metastasis, we generated PC-3(Luc) prostate cancer cells with CD55 siRNA-targeted disruption. We found that PC-3(Luc)/CD55 siRNA constructs in SCID mice resulted in a significant attenuation of overall tumor burden. Further investigation into the mechanisms of CD55-mediated tumor cell/microenvironment interaction is necessary to understand the role of CD55 in tumor cell survival and metastatic lesion formation.

Animals↗
PubMed2006

CCL2 is a potent regulator of prostate cancer cell migration and proliferation.

Tumor cells in the bone interact with the microenvironment to promote tumor cell survival and proliferation, resulting in a lethal phenotype for patients with advanced prostate cancer. Monocyte chemoattractant protein 1 (CCL2) is a member of the CC chemokine family and is known to promote monocyte chemotaxis to sites of inflammation. Here we have shown that human bone marrow endothelial (HBME) cells secrete significantly higher levels of CCL2 compared to human aortic endothelial cells and human dermal microvascular endothelial cells. Furthermore, we demonstrate that CCL2 is a potent chemoattractant of prostate cancer epithelial cells, and that stimulation of PC-3 and VCaP cells resulted in a dose-dependent activation of PI3 kinase/Akt signaling pathway. Activation of the PI3 kinase/Akt pathway was found to be vital to the proliferative effects of CCL2 stimulation of both PC-3 and VCaP cells. Additionally, CCL2 stimulated the phosphorylation of p70-S6 kinase (a downstream target of Akt) and induced actin rearrangement, resulting in a dynamic morphologic change indicative of microspike formation. These data suggest that bone marrow endothelial cells are a major source of CCL2, and that an elevated secretion of CCL2 recruits prostate cancer epithelial cells to the bone microenvironment and regulates their proliferation rate.

Aged↗
PubMed2006

Phase II evaluations of cilengitide in asymptomatic patients with androgen-independent prostate cancer: scientific rationale and study design.

Two randomized trials demonstrated an improvement in survival with docetaxel-based chemotherapy for patients with metastatic, androgen-independent prostate disease. However, the effect of current therapy is suboptimal in that it is complicated by toxicities and has no curative potential. Cilengitide (EMD121974; NSC 707544), is a potent selective alphavbeta3 and alphavbeta5 integrin antagonist. Integrins are cell surface receptors that mediate a variety of cell activities including endothelial cell proliferation and migration. Blocking the ligation of integrins by antagonists promotes apoptosis of proliferative angiogenic cells, thereby suspending new blood vessel formation, which is essential for the growth of malignant disease. In prostate cancer specifically, integrins are known to be involved in metastases with differential expression on tumor cells. Tumors and vascular endothelial cells produce factors, such as vascular endothelial growth factor and basic fibroblast growth factor, that promote neovascularization, which has been implicated in prostate cancer progression. Cilengitide has been shown to inhibit alphavbeta3- and alphavbeta5-mediated cell adhesion and block in vitro endothelial cell migration. In vivo experiments demonstrated that cilengitide inhibited cytokine-induced basic fibroblast growth factor- and vascular endothelial growth factor-mediated angiogenesis in a dose-dependent manner. Cilengitide also inhibited tumor growth in various in vivo systems. Two Cancer Therapy Evaluation Program-sponsored, multicenter, phase II trials are designed to evaluate the safety and efficacy of this agent in patients with androgen-independent prostate cancer. National Cancer Institute trial 6735 is evaluating cilengitide at 2000 mg in patients with nonmetastatic androgen-independent prostate cancer, and National Cancer Institute trial 6372 is evaluating 2 dose levels of cilengitide, 500 mg or 2000 mg, intravenously twice weekly in patients with metastatic prostate cancer.

Androgens↗
PubMed2005

Pathogenesis and treatment of prostate cancer bone metastases: targeting the lethal phenotype.

Traditionally, prostate cancer treatment, as well as all cancer treatment, has been designed to target the tumor cell directly via various hormonal and chemotherapeutic agents. Recently, the realization that cancer cells exist in complex microenvironments that are essential for the tumorigenic and metastatic potential of the cancer cells is starting the redefine the paradigm for cancer therapy. The propensity of prostate cancer cells to metastasize to bone is leading to the design of novel therapies targeting both the cancer cell as well as the bone microenvironment. Tumor cells in the bone interact with the extracellular matrix, stromal cells, osteoblasts, osteoclasts, and endothelial cells to promote tumor-cell survival and proliferation leading to a lethal phenotype that includes increased morbidity and mortality for patients with advanced prostate cancer. Several strategies are being developed that target these complex tumor cell-microenvironment interactions and target the signal transduction pathways of other cells important to the development of metastases, including the osteoclasts, osteoblasts, and endothelial cells of the bone microenvironment. Current and new therapies in metastatic prostate cancer will comprise a multitargeted approach aimed at both the tumor cell and the tumor microenvironment. Here, we review the current therapeutic strategies for targeting the prostate cancer-bone microenvironment and several single- and multiagent targeted approaches to the treatment of advanced prostate cancer that are under development.

Bone Neoplasms↗
PubMed2005

Recurrent fusion of TMPRSS2 and ETS transcription factor genes in prostate cancer.

Recurrent chromosomal rearrangements have not been well characterized in common carcinomas. We used a bioinformatics approach to discover candidate oncogenic chromosomal aberrations on the basis of outlier gene expression. Two ETS transcription factors, ERG and ETV1, were identified as outliers in prostate cancer. We identified recurrent gene fusions of the 5' untranslated region of TMPRSS2 to ERG or ETV1 in prostate cancer tissues with outlier expression. By using fluorescence in situ hybridization, we demonstrated that 23 of 29 prostate cancer samples harbor rearrangements in ERG or ETV1. Cell line experiments suggest that the androgen-responsive promoter elements of TMPRSS2 mediate the overexpression of ETS family members in prostate cancer. These results have implications in the development of carcinomas and the molecular diagnosis and treatment of prostate cancer.

Androgens↗
PubMed2005

A paradigm for the treatment of prostate cancer bone metastases based on an understanding of tumor cell-microenvironment interactions.

The pliability of cancer cells to mutate into several different phenotypes in an attempt to find one that will survive and colonize at the metastatic site is a tremendous "hurdle" to overcome in designing novel cancer therapeutics. New targets of therapy are essential if we are to effectively overcome the evasiveness of cancer. The interaction between the tumor cell and the surrounding microenvironment creates a vicious cycle that perpetuates disease survival and progression. The future of cancer therapy resides in the ability to focus on the recruited and exploited relationships of the cancer cell with the host environment. These therapies target cancer cell growth early and interrupt the vicious cycle that is created by the tumor cells interacting with bone components by inhibiting osteoclasts, osteoblasts, stromal cells, and endothelial cells. They alter the bone microenvironment, creating a hostile "soil" that prevents the "seed" from developing into bone metastases and represent a potential new platform for the development of prostate cancer therapeutics.

Bone Neoplasms↗
PubMed2005

PAR1-mediated NFkappaB activation promotes survival of prostate cancer cells through a Bcl-xL-dependent mechanism.

We have previously reported that protease-activated receptor 1 (PAR1 or thrombin receptor) is over-expressed in metastatic prostate cancer cell lines compared to prostate epithelial cells. In this study, we examined 1,074 prostate biopsies by tissue microarray analysis and demonstrated that PAR1 expression is significantly increased in prostate cancer compared to normal prostate epithelial cells and benign prostatic hyperplasia. We hypothesized that PAR1 activation contributed to prostate cancer cell progression. We demonstrated that stimulation of PAR1 by thrombin or thrombin receptor activating peptide (TRAP6), in androgen-independent DU145 and PC-3 cells resulted in increased DNA binding activity of the NFkappaB p65 subunit. IL-6 and IL-8 levels were also elevated in conditioned media by at least two-fold within 4-6 h of PAR1 activation. This induction of cytokine production was abrogated by pretreatment of cells with the NFkappaB inhibitor caffeic acid phorbol ester. The p38 and ERK1/2 MAPK signaling cascades were also activated by PAR1 stimulation, whereas the SAPK/JNK pathway was unaffected. Inhibition of p38 and ERK1/2 by SB-203589 and PD-098059, respectively, did not abrogate NFkappaB activity, suggesting an independent induction of NFkappaB by PAR1 stimulation. Furthermore, TUNEL assay showed that activation of PAR1 attenuated docetaxel induced apoptosis through the upregulation of the Bcl-2 family protein Bcl-xL. Akt activation was not observed, suggesting that drug resistance induced by PAR1 was independent of PI3K signaling pathway. Because thrombin and PAR1 are over-expressed in prostate cancer patients, targeting the inhibition of their interaction may attenuate NFkappaB signaling transduction resulting in decreased drug resistance and subsequent survival of prostate cancer cells.

Antineoplastic Agents, Phytogenic↗
PubMed2005

Autoantibody signatures in prostate cancer.

BACKGROUND: New biomarkers, such as autoantibody signatures, may improve the early detection of prostate cancer. METHODS: With a phage-display library derived from prostate-cancer tissue, we developed and used phage protein microarrays to analyze serum samples from 119 patients with prostate cancer and 138 controls, with the samples equally divided into training and validation sets. A phage-peptide detector that was constructed from the training set was evaluated on an independent validation set of 128 serum samples (60 from patients with prostate cancer and 68 from controls). RESULTS: A 22-phage-peptide detector had 88.2 percent specificity (95 percent confidence interval, 0.78 to 0.95) and 81.6 percent sensitivity (95 percent confidence interval, 0.70 to 0.90) in discriminating between the group with prostate cancer and the control group. This panel of peptides performed better than did prostate-specific antigen (PSA) in distinguishing between the group with prostate cancer and the control group (area under the curve for the autoantibody signature, 0.93; 95 percent confidence interval, 0.88 to 0.97; area under the curve for PSA, 0.80; 95 percent confidence interval, 0.71 to 0.88). Logistic-regression analysis revealed that the phage-peptide panel provided additional discriminative power over PSA (P<0.001). Among the 22 phage peptides used as a detector, 4 were derived from in-frame, named coding sequences. The remaining phage peptides were generated from untranslated sequences. CONCLUSIONS: Autoantibodies against peptides derived from prostate-cancer tissue could be used as the basis for a screening test for prostate cancer.

Aged↗