Density-dependent regulation of epidermal growth factor receptor expression in DU 145 human prostate cancer cells

Identification of prostate cancer associated genes for diagnosis and prognosis: a modernized in silico approach

Prostate cancer (PCa) ranks as the second leading cause of cancer-related deaths in men. Diagnosing PCa relies on molecular markers known as diagnostic biomarkers, while prognostic biomarkers are used to identify key proteins involved in PCa treatments. This study aims to gather PCa-associated genes and assess their potential as either diagnostic or prognostic biomarkers for PCa. A corpus of 152,064 PCa-related data from PubMed, spanning from May 1936 to December 2020, was compiled. Additionally, 4199 genes associated with PCa terms were collected from the National Center of Biotechnology Information (NCBI) database. The PubMed corpus data was extracted using pubmed.mineR to identify PCa-associated genes. Network and pathway analyses were conducted using various tools, such as STRING, DAVID, KEGG, MCODE 2.0, cytoHubba app, CluePedia, and ClueGO app. Significant marker genes were identified using Random Forest, Support Vector Machines, Neural Network algorithms, and the Cox Proportional Hazard model. This study reports 3062 unique PCa-associated genes along with 2518 corresponding unique PMIDs. Diagnostic markers such as IL6, MAPK3, JUN, FOS, ACTB, MYC, and TGFB1 were identified, while prognostic markers like ACTB and HDAC1 were highlighted in PubMed. This suggests that the potential target genes provided by PubMed data outweigh those in the NCBI database.

Her-2/Neu Receptor in Prostate Cancer Development and Progression to Androgen Independence

Development of prostate cancer and progression to androgen-independent disease is correlated with increased expression of growth factors and receptors capable of establishing autocrine and/or paracrine growth-stimulatory loops. A thorough review was made of the current literature and recent abstract presentations at scientific meetings focusing on the role of the HER-2/neu (c-erbB2) receptor in prostate cancer and the potential clinical usefulness of its specific inhibitors. In the past 10 years, conflicting results on HER-2/neu expression in prostate cancer have been reported. More recently, four studies have shown experimental evidence of HER-2/neu in the development of prostate cancer and, more specifically, in the progression to a hormone-refractory clinical behavior. Furthermore, it has been proposed that HER-2 family and androgen receptors function synergistically in the absence of androgen, which suggests a crosstalk between the HER-2/neu and androgen receptor pathways. Finally, clinical trials are in progress in prostate cancer patients to test novel agents that selectively interfere with HER-2/neu activity.

Effects of simulated microgravity on DU 145 human prostate carcinoma cells

The high aspect rotating-wall vessel (HARV) was recently designed by NASA to cultivate animal cells in an environment that simulates microgravity. This work examines the effects of HARV cultivation on DU 145 human prostate carcinoma cells. In the HARV, these prostate cells grew in suspension on Cytodex-3 microcarrier beads to form bead aggregates with extensive three-dimensional growth between beads and on the aggregate surface. HARV and spinner-flask control cultures of DU 145 cells had similar doubling times, but the former was characterized by a higher percentage of G(1)-phase cells, larger bead aggregates, enhanced development of filopodia and microvilli-like structures on the aggregate surface, and stronger staining for select cytoskeletal proteins (cytokeratins 8 and 18, actin, and vimentin). When compared with static controls grown in a T-flask and Transwell insert, HARV cultures grew more slowly and differences in the cell cycle and immunostaining became more pronounced. These results suggest that HARV cultivation produced a culture that was less aggressive from the perspective of proliferation, more differentiated and less pliant than any of the three control cultures examined in this work. Possible factors effecting this change are discussed including turbulence and three-dimensional growth.

Action, localization and structure-function relationship of growth factors and their receptors in the prostate

Whereas the direct action of sex steroids, namely of androgens, on prostate cell division was questioned as early as in the 1970s, and remains so, the interest in prostatic growth factors (GFs) is rather recent but has expanded tremendously in the last five years. This lag period can be partly explained by the fact that, at the time, androgen receptors had just been discovered, and newly developed hormonal regimens or strategies to treat patients with prostate carcinoma (PCa) or epithelioma had generated great enthusiasm and hopes in the medical and scientific community. Another point to consider was the difficulty in maintaining prostate tissues in organ cultures and the relative novelty of culturing prostate epithelial cells in monolayers. Failures of sex steroids to elicit a direct positive response on prostate cell divisionin vitro, as seenin vivo, were interpreted as resulting from inappropriate models or culture conditions. However, the increasing number of reports confirming the lack of mitogenic activity of sex steroidsin vitro, coupled with the powerful mitogenic activity of GFs displayed in other systems, the discovery of GF receptors (GF-Rs), and the elucidation of their signalling pathways showing sex steroid receptors as potential substrates of GF-activated protein kinases gradually led to an increased interest in the putative role of GFs in prostate physiopathology. Of utmost importance was the recognition that hormone refractiveness was responsible for PCa progression, and for the poor outcome of patients with advanced disease under endocrine therapies. This problem remains a major issue and it raises several key questions that need to be solved at the fundamental and clinical levels.

In vitro and in vivo radiosensitization with AZD6244 (ARRY-142886), an inhibitor of mitogen-activated protein kinase/extracellular signal-regulated kinase 1/2 kinase

PURPOSE

The mitogen-activated protein (MAP) kinase pathway is important for cell proliferation, survival, and differentiation, and is frequently up-regulated in cancers. The MAP kinase pathway is also activated after exposure to ionizing radiation. We investigated the effects of AZD6244 (ARRY-142886), an inhibitor of MAP kinase/extracellular signal-regulated kinase 1/2, on radiation response.

EXPERIMENTAL DESIGN

The effects of AZD6244 on the in vitro radiosensitivity of human cancer cell lines (A549, MiaPaCa2, and DU145) were evaluated using clonogenic assays. DNA damage repair was evaluated using gammaH2AX, and mitotic catastrophe was measured using nuclear fragmentation. Cell cycle effects were measured with flow cytometry. Growth delay was used to evaluate the effects of AZD6244 on in vivo tumor radiosensitivity.

RESULTS

Exposure of each cell line to AZD6244 before irradiation resulted in an increase in radiosensitivity with dose enhancement factors at a surviving fraction of 0.1, ranging from 1.16 to 2.0. No effects of AZD6244 on radiation-induced apoptosis or persistence of gammaH2AX foci after irradiation were detected. Cells treated with AZD6244 had an increased mitotic index and decreased Chk1 phosphorylation at 1 and 2 hours after irradiation. Mitotic catastrophe was increased in cells receiving AZD6244 and irradiation compared with the single treatments. In vivo studies revealed that AZD6244 administration to mice bearing A549 tumor xenografts resulted in a greater than additive increase in radiation-induced tumor growth delay (dose enhancement factor of 3.38).

CONCLUSIONS

These results indicate that AZD6244 can enhance tumor cell radiosensitivity in vitro and in vivo and suggest that this effect involves an increase in mitotic catastrophe.

Gefitinib combined with endocrine manipulation in patients with hormone-refractory prostate cancer: quality of life and surrogate markers of activity

We investigated efficacy of gefitinib in hormone-refractory prostate cancer. Between March 2003 and December 2004, 23 patients with hormone-refractory prostate cancer were assigned to receive 250 mg oral gefitinib daily in addition to antiandrogen and luteinizing hormone-releasing hormone analogue for at least 2 months or until disease progression. Patients with progression stopped antiandrogen therapy, and received gefitinib and the luteinizing hormone-releasing hormone analogue. Serum HER2 and epidermal growth factor receptor extracellular domain were evaluated every 2 months. Gefitinib treatment did not result in any objective measurable response or responses in prostate-specific antigen. Median time to progression was 70 days (33-336). Median overall survival was 293 days (25-75 percentile: 235-349). HER2 extracellular domain mean value was 9.6 ng/ml (range 6.9-13.3) at basal time and was 10.1 (range 6.0-14.1) after 2 months. Epidermal growth factor receptor mean basal value was 51.0 ng/ml (range 41.4-75.3). After 2 months of treatment the mean value was 51.1 ng/ml (range 41.5-61.4). One patient had reduction in the pain score from baseline without an increase in the analgesic score. Four patients (17%) out of 23 had pain progression with an increase from baseline of at least 25% in the analgesic score. The study was discontinued before target accrual was reached owing to lack of efficacy of the drug. Our results do not support the efficacy of gefitinib in combination with endocrine treatment for hormone-refractory prostate cancer.

Epidermal growth factor receptor (ErbB1) expression in prostate cancer progression: correlation with androgen independence

BACKGROUND

The role of the epidermal growth factor receptor (ErbB1) in the progression of prostate cancer is incompletely understood.

METHODS

Tissue microarrays from hormone-naive and advanced androgen-independent tumors were used to investigate the role of ErbB1 in prostate cancer progression.

RESULTS

ErbB1 expression in tumor tissues was strongly associated with hormone-refractory status (odds ratio = 6.67, 95% CI = (2.6, 17.4), P = 0.0001). However, ErbB1 overexpression was not a statistically significant covariate in a multivariate proportional hazards model for biochemical failure of hormone-naïve prostate cancer. Moreover, ErbB1 overexpression was not associated with tumor differentiation (P = 0.44), positive margins (P = 0.53), seminal vesicle invasion (P = 0.69), extraprostatic extension (P = 0.10), or preoperative PSA (P = 0.18) in the hormone-naïve group.

CONCLUSIONS

These findings are consistent with a model in which ErbB1 expression increases during the development of the androgen-independent state, and suggest that drugs targeted toward ErbB signaling could be of therapeutic relevance in the management of advanced prostatic carcinoma.

Randomized phase II study of two doses of gefitinib in hormone-refractory prostate cancer: a trial of the National Cancer Institute of Canada-Clinical Trials Group

PURPOSE

Overexpression of the epidermal growth factor receptor has been demonstrated in advanced prostate cancer and is associated with a poor outcome. A multi-institutional, randomized, phase II study was undertaken by the National Cancer Institute of Canada-Clinical Trials Group to evaluate the efficacy and toxicity of two doses of oral gefitinib in patients with minimally symptomatic, hormone-refractory prostate cancer (HRPC).

PATIENTS AND METHODS

Between July and November 2001, 40 patients with HRPC and increasing prostate-specific antigen (PSA) or progression in measurable disease who had not received prior chemotherapy were randomly assigned to 250 mg (n = 19) or 500 mg (n = 21) oral gefitinib daily continuously. The primary end points were PSA response rate and objective measurable response. Functional Assessment of Cancer Therapy Prostate Cancer Subscale (FACT-P) quality-of-life questionnaires were completed at baseline and during treatment.

RESULTS

None of the patients demonstrated a PSA or objective measurable response. Five (14.3%) of 35 assessable patients had stable PSA (one patient at 250 mg and four patients at 500 mg), and five patients (14.3%) had a best response of stable disease (duration, 2.5 to 16.8 months). No significant effect on the rate of increase in PSA was seen. The most common drug-related nonhematologic toxicities observed were grade 1 to 2 diarrhea (250 mg, 65%; 500 mg, 56%), fatigue (250 mg, 29%; 500 mg, 33%), and grade 1 to 2 skin rash (250 mg, 24%; 500 mg, 39%). FACT-P scores decreased during treatment, indicating worsening of symptoms compared with baseline.

CONCLUSION

Gefitinib did not result in any responses in PSA or objective measurable disease at either dose level. Gefitinib has minimal single-agent activity in HRPC.

Her-2/neu expression in prostate cancer: a dynamic process?

The clinical effects of targeting Her-2/neu in prostate carcinoma are not known. This study explores the feasibility of molecular profiling to determine the correlation between Her-2/neu expression and hormonal sensitivity. Patients with progressive androgen-independent prostate carcinoma were eligible to participate in the study. Her-2/neu expression was assessed on pretreatment tissue specimens and on bone marrow obtained in progressive androgen-independent disease. Her-2/neu expression was evaluated by immunohistochemistry and by fluorescence in situ hybridization in a consecutive series of 26 progressive androgen-independent prostate cancer patients. Twenty four bone marrow biopsy specimens and 16 prostate biopsies from 26 patients were analyzed. These biopsies were categorized by androgen sensitivity at the time of the biopsy. In total, 90% of specimens from bone marrow were Her-2/neu positive, and 10% of the specimens were Her-2/neu negative. Of the prostate biopsies, all were from patients with androgen-dependent disease. Three of 13 androgen-dependent prostate biopsies (23%) overexpressed Her-2/neu. Of the 10 tumor samples analyzed by fluorescence in situ hybridization, genomic amplification of the Her-2/neu locus was not detected in any of the metastatic prostate tumors. Her-2/neu expression varies with the clinical state of patients with prostate carcinoma: Accurate Her-2/neu profiling requires sampling metastatic tissue in patients with metastatic disease. Her-2/neu sampling from metastatic prostate carcinoma is not feasible until more reliable and practical methods can be developed.

Human prostate cancer risk factors

Prostate cancer has the highest prevalence of any nonskin cancer in the human body, with similar likelihood of neoplastic foci found within the prostates of men around the world regardless of diet, occupation, lifestyle, or other factors. Essentially all men with circulating androgens will develop microscopic prostate cancer if they live long enough. This review is a contemporary and comprehensive, literature-based analysis of the putative risk factors for human prostate cancer, and the results were presented at a multidisciplinary consensus conference held in Crystal City, Virginia, in the fall of 2002. The objectives were to evaluate known environmental factors and mechanisms of prostatic carcinogenesis and to identify existing data gaps and future research needs. The review is divided into four sections, including 1) epidemiology (endogenous factors [family history, hormones, race, aging and oxidative stress] and exogenous factors [diet, environmental agents, occupation and other factors, including lifestyle factors]); 2) animal and cell culture models for prediction of human risk (rodent models, transgenic models, mouse reconstitution models, severe combined immunodeficiency syndrome mouse models, canine models, xenograft models, and cell culture models); 3) biomarkers in prostate cancer, most of which have been tested only as predictive factors for patient outcome after treatment rather than as risk factors; and 4) genotoxic and nongenotoxic mechanisms of carcinogenesis. The authors conclude that most of the data regarding risk relies, of necessity, on epidemiologic studies, but animal and cell culture models offer promise in confirming some important findings. The current understanding of biomarkers of disease and risk factors is limited. An understanding of the risk factors for prostate cancer has practical importance for public health research and policy, genetic and nutritional education and chemoprevention, and prevention strategies.

Involvement of Growth Factor Receptors of the Epidermal Growth Factor Receptor Family in Prostate Cancer Development and Progression to Androgen Independence

The development of prostate cancer and the progression from a normal prostate epithelium to androgen-dependent cancer and eventually to hormone-refractory prostate cancer is a multistep process involving several changes in the function of different growth-regulatory signals. In the past 10 years, conflicting results on epidermal growth factor receptor (EGFR) family expression in prostate cancer have been reported. These differences may result from technical differences, lack of standardization of immunohistochemical assays, or different scoring methodologies. Recently, 4 studies have shown experimental evidence of a role of the EGFR family, particularly ErbB-2, in the development of prostate cancer and, more specifically, in the progression to hormone-refractory clinical behavior. These 4 studies were similar in some relevant aspects, such as the patient population. In fact, the patients in each study were divided into 3 groups that represent the progression of prostate cancer. In 3 of 4 studies, a statistically significant increase in ErbB-2 expression was detected by immunohistochemistry in the progression from hormone-dependent to hormone-independent disease. The expression of EGFR was also evaluated in 1 of the 4 studies. In a recent report from our group, a significant increase in EGFR expression was observed in patients treated with radical surgery, in patients who received hormonal therapy as primary therapy before radical prostatectomy, and, finally, in patients with metastatic and hormone-refractory disease. It has been proposed that EGFR family receptors and androgen receptors function synergistically in the absence of androgen suggesting cross-talk between the ErbB-2 and androgen receptor pathways, and that mitogen-activated protein kinase and phosphatidylinositol 3-kinase can be considered the transduction pathways. Finally, clinical trials are currently in progress in patients with prostate cancer testing novel agents that selectively interfere with these receptors, such as trastuzumab, an anti- ErbB-2 monoclonal antibody, and gefitinib (ZD1839, Iressa), a small-molecule selective EGFR tyrosine kinase inhibitor.

A tyrosine kinase profile of prostate carcinoma

Tyrosine kinases play central roles in the growth and differentiation of normal and tumor cells. In this study, we have analyzed the general tyrosine kinase expression profile of a prostate carcinoma (PCA) xenograft, CWR22. We describe here an improved reverse transcriptase-PCR approach that permits identification of nearly 40 different kinases in a single screening; several of these kinases are newly cloned kinases and some are novel. According to this, there are 11 receptor kinases, 9 nonreceptor kinases, and at least 7 dual kinases expressed in the xenograft tissue. The receptor kinases include erbB2, erbB3, Ret, platelet-derived growth factor receptor, sky, nyk, eph, htk, sek (eph), ddr, and tkt. The nonreceptor kinases are lck, yes, abl, arg, JakI, tyk2, and etk/bmx. Most of the dual kinases are in the mitogen-activating protein (MAP) kinase-kinase (MKK) family, which includes MKK3, MKK4, MEK5, and a novel one. As a complementary approach, we also analyzed by specific reverse transcriptase-PCR primers the expression profile of erbB/epidermal growth factor receptor family receptors in a variety of PCA specimens, cell lines, and benign prostatic hyperplasia. We found that erbB1, -2, and -3 are often coexpressed in prostate tissues, but not in erbB4. The information established here should provide a base line to study the possible growth and oncogenic signals of PCA.

Regulation of prostatic growth and function by peptide growth factors

Polypeptide growth factors are positive and negative regulators of prostatic growth and function. Expression and biological effects of epidermal growth factor (EGF), transforming growth factors (TGFs) alpha and beta, fibroblast growth factors (FGFs), and insulin-like growth factors (IGFs) in the prostate have been extensively studied. EGF and TGF alpha, which share the same receptor, are strong mitogens for prostatic epithelial and stromal cells. Their paracrine mode of action in normal tissue and early-stage tumors is apparently altered towards an autocrine stimulation in hormone-independent tumors, which gain the ability to produce TGF alpha by themselves. TGF beta has a dual role in the regulation of prostatic growth. It inhibits growth of prostatic epithelial cells in culture and mediates programmed cell death after androgen withdrawal. However, advanced prostatic carcinomas become insensitive to the inhibitory effect of TGF beta. Several members of the FGF family have been identified in the prostate. They are mainly or exclusively expressed in the stromal cells, and stimulate the epithelial cells. In the rat Dunning tumor model, progression is accompanied by distinct changes in the expression of FGFs and their receptors. In the hyperplastic tissue, basic FGF (bFGF) is accumulated. This growth factor is also a potent angiogenic inducer, expression of which may determine the metastatic capability of a tumor. IGFs are paracrine growth stimulators in the normal and hyperplastic prostate. It is still under consideration whether prostatic cancer cells gain the ability to produce IGF-I by themselves and thus shift to an autocrine mode of IGF-I stimulation. Growth factors also interact with the androgen-signaling pathway. IGF-I in particular, other growth factors as well, can activate the androgen receptor.

Inhibition of chemomigration of a human prostatic carcinoma cell (TSU-pr1) line by inhibition of epidermal growth factor receptor function

Chemoattractants expressed at bony sites and pelvic lymph nodes are thought to promote the preferential metastasis of human prostate tumor cells to these organs. Epidermal growth factor (EGF) is a potent chemoattractant for several human metastatic prostate tumor cell lines, including the TSU-pr1 cell line, and EGF has been localized to the stroma of both bony sites and pelvic lymph nodes in humans. Hence, we investigated whether the TSU-pr1 cell line expresses a functional EGF receptor (EGFR), which when antagonized reduces EGF-mediated chemomigration of this cell line. In this context, the EGFR immunoprecipitated from cell lysates of TSU-pr1 cells comigrated with the EGFR from A431 cells at a molecular weight of 170 kD. Addition of human EGF (hEGF) to the TSU-pr1 cells for 5 min stimulated the dose-dependent biphasic phosphorylation of the EGFR, with maximal stimulation of EGFR phosphorylation occurring at 2 ng/ml hEGF. In addition, treatment of hEGF-stimulated (2 ng/ml) TSU-pr1 cells with 0.5 microgram/ml anti-hEGF monoclonal antibody or 100 nM staurosporine inhibited EGFR phosphorylation. Conversely, as negative controls, treatment of hEGF-stimulated (2 ng/ml) TSU-pr1 cells with K252a or dimethyl sulfoxide (DMSO) vehicle did not inhibit EGFR phosphorylation. TSU-pr1 cells were stimulated to migration in 4 hr across Boyden chambers in response to 10 ng/ml hEGF. Treatment of the TSU-pr1 cells with anti-hEGFR monoclonal antibody inhibited in a dose-dependent manner the chemomigration of the TSU-pr1 cells across Boyden chambers. Similarly, treatment of the TSU-pr1 cells with staurosporine inhibited in a dose-dependent manner the chemomigration of the TSU-pr1 cells across Boyden chambers. These results demonstrate that antagonists of hEGF-mediated hEGFR phosphorylation also antagonize chemomigration of the TSU-pr1 cells across Boyden chambers, suggesting that antagonists of the EGFR in prostate cancer may be useful in the treatment of metastatic disease.

Epidermal growth factor (EGF) promotes chemomigration of a human prostate tumor cell line, and EGF immunoreactive proteins are present at sites of metastasis in the stroma of lymph nodes and medullary bone

Prostate tumor cells preferentially metastasize to bony sites and lymph nodes at a frequency in excess of that which would be predicted by random tumor cell dissemination. In order to determine whether chemoattractants in these organs promote organ-specific metastasis, we utilized human cell lines derived from and/or related to these organs as sources of potential chemoattractants. Secretory proteins derived from the cell lines MG-63 (osteosarcoma), SK-ES-1 (Ewing's sarcoma), and KG-1 (leukemia) stimulated chemomigration of the TSU-pr1 prostate tumor cells in a dose-dependent manner in Boyden chambers. In addition, secretory proteins from a human prostatic stromal cell line (hPS) and from the TSU-Pr1 prostate tumor cell line were also able to stimulate chemomigration of the TSU-pr1 cells through Boyden chambers. Since lymph nodes and bony sites represent organs of hematopoietic/lymphoid proliferation and activation, we undertook identification of specific cytokines present at these sites which may promote the chemomigration of prostate tumor cells. In this context, the cytokines interleukin-1 alpha, interleukin-2, interleukin-6, tumor necrosis factor-beta, transforming growth factor-beta, interferon alpha 2-a, and granulocyte-macrophage colony-stimulating factor did not stimulate chemomigration of the TSU-pr1 prostate tumor cell line. In contrast, the cytokine epidermal growth factor (EGF) stimulated chemomigration of the TSU-pr1 prostate tumor cells through the Boyden chambers in a dose-dependent manner. Western blot analysis of secretory proteins from the cell lines KG-1, SK-ES-1, MG-63, hPS, and TSU-pr1 identified EGF-immunoreactive proteins in all cases. In addition, EGF immunoreactivity was localized to the stroma of the human prostate, the osteogenic stroma of pelvic medullary bone, and the stroma within the capsule and trabeculae of pelvic lymph nodes. Hence, these results demonstrate that the cytokine EGF promotes the chemomigration of the TSU-pr1 prostate tumor cell line, and that EGF within the stroma of pelvic lymph nodes and medullary bone may act as a chemoattractant for prostate tumor cells, thereby facilitating the preferential formation of metastatic foci within these organs.