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Simon Wilkinson

Publications and source records attributed to Simon Wilkinson.

11 recordsLinked to original sources

DRAM links autophagy to p53 and programmed cell death.

It is clear that changes in autophagy and autophagy regulators occur during tumor development and that this can have profound effects in certain tumor settings. The fact that p53, a key tumor suppressor mutated in approximately 50% of human cancers, has now also been shown to induce autophagy, has placed autophagy center stage in the minds of those interested in the development and treatment of malignant disease. p53 is a transcription factor that responds to cellular stress and prevents the propagation of cells which may otherwise form a tumor. The recent discovery, therefore, of DRAM (damage-regulated autophagy modulator) as a new p53 target which modulates autophagy is a major step forward in understanding how p53 controls autophagy and how this relates to tumor suppression. DRAM is a lysosomal protein that is not only critical for the ability of p53 to induce autophagy, but also for p53's ability to induce programmed cell death--a facet of p53 considered central to its tumor-suppressive effects. The fact that DRAM is also inactivated in certain cancers underscores its importance and highlights the possibility that autophagy may have a more profound role in cancer than was first believed.

Apoptosis↗

Analysis, interpretation, and extrapolation of dermal permeation data using diffusion-based mathematical models.

New dermal penetration data have been measured in both "infinite" and finite dose experiments on a range of compounds of varying lipophilicities. The data are analyzed, using parameter fitting, to determine the values of parameters governing the overall skin absorption processes. Two one-dimensional diffusion models are used. The first is novel, and well suited to the modeling of dermal uptake in occupational exposure scenarios. The second is an implementation of a model taken from the literature. The models are compared in a variety of exposure scenarios, and exhibit good mutual agreement. Both successfully reproduce expected features of the absorption process. Penetration parameters are determined by analyzing both infinite and finite dose data. Prediction of dermal absorption with finite dose scenarios is carried out and compared with experimental data obtained under these conditions. Parameters determined may also have an important role in improving the reliability of predictive QSARs used to estimate the extent of penetration of untested molecules.

Administration, Cutaneous↗

DRAM, a p53-induced modulator of autophagy, is critical for apoptosis.

Inactivation of cell death is a major step in tumor development, and p53, a tumor suppressor frequently mutated in cancer, is a critical mediator of cell death. While a role for p53 in apoptosis is well established, direct links to other pathways controlling cell death are unknown. Here we describe DRAM (damage-regulated autophagy modulator), a p53 target gene encoding a lysosomal protein that induces macroautophagy, as an effector of p53-mediated death. We show that p53 induces autophagy in a DRAM-dependent manner and, while overexpression of DRAM alone causes minimal cell death, DRAM is essential for p53-mediated apoptosis. Moreover, analysis of DRAM in primary tumors revealed frequent decreased expression often accompanied by retention of wild-type p53. Collectively therefore, these studies not only report a stress-induced regulator of autophagy but also highlight the relationship of DRAM and autophagy to p53 function and damage-induced programmed cell death.

Amino Acid Sequence↗

Cdc42-MRCK and Rho-ROCK signalling cooperate in myosin phosphorylation and cell invasion.

Actomyosin contractility is a mechanism by which cells exert locomotory force against their environment. Signalling downstream of the small GTPase Rho increases contractility through Rho-kinase (ROCK)-mediated regulation of myosin-II light chain (MLC2) phosphorylation. Cdc42 signalling has been shown to control cell polarity. Tumour cells can move through a three-dimensional matrix with either a rounded morphology characterized by Rho-ROCK dependence or with an elongated morphology characterized by Rho-ROCK independence. Here we show that contractility necessary for elongated morphology and invasion can be generated by Cdc42-MRCK signalling. MRCK (myotonic dystrophy kinase-related Cdc42-binding kinase) cooperates with ROCK in the maintenance of elongated morphology and invasion and either MRCK or ROCK is sufficient for MLC2 phosphorylation, through the inhibitory phosphorylation of myosin phosphatase. By contrast, in rounded ROCK-dependent movement, where MLC2 phosphorylation is higher, MRCK has a smaller role. Our data show that a Cdc42-MRCK signal mediates myosin-dependent cell motility and highlight convergence between Rho and Cdc42 signalling.

Actomyosin↗

An evaluation of intermediate-dose ketoconazole in hormone refractory prostate cancer.

OBJECTIVES: The management of hormone refractory prostate cancer remains controversial. Among the options, second-line hormonal therapy is commonly used. We investigated the efficacy of ketoconazole, an inhibitor of testicular and adrenal androgen biosynthesis, for treating patients with advanced hormone refractory prostate cancer. METHODS: The study comprised 38 patients with progressive disease despite combined androgen blockade. Treatment consisted of intermediate-dose ketoconazole (300mg three times daily) and replacement hydrocortisone. Patients were monitored clinically and with serial psa measurements every 3 months. the principal endpoint was psa response. RESULTS: Of the 38 patients, 21 (55.3%) showed a decrease in PSA >50% (95% confidence interval 38.3%-71.4%) with a median duration of 6 months (range 3-48 months). A PSA reduction >50% was seen in 21 of 34 patients (61.8%) with established metastases. Thirteen patients (34.2%), all of whom had metastases, exhibited a PSA decrease >80% (95% confidence interval 19.6%-51.4%) with a median duration of 9 months (range 3-48 months). Age, PSA at diagnosis, Gleason score and bone scan result were not significantly associated with response to ketoconazole treatment in univariate or multivariate analyses. For the entire study group, the median time to progression was 5 months (range 0-27 months) and the median survival was 12 months (range 3-48 months). Overall, 12 patients (31.6%) reported toxicity related to intermediate-dose ketoconazole but only 6 patients (15.8%) discontinued therapy due to intolerable side effects. CONCLUSION: It is apparent from this study that a reasonable percentage of patients failing standard hormonal therapy respond favourably to intermediate-dose ketoconazole and that toxicity is mild. In the absence of studies demonstrating better survival with chemotherapy, we believe that a trial of ketoconazole should be considered when progression occurs on hormone therapy.

Aged↗

The role of 111indium-capromab pendetide imaging for assessing biochemical failure after radical prostatectomy.

PURPOSE: Conventional imaging modalities, such as computerized tomography and magnetic resonance imaging, lack sensitivity and specificity for detecting recurrent prostate cancer after radical surgery. We evaluated the role of the indium-capromab pendetide scan, otherwise known as the ProstaScint (Cytogen Corp., Princeton, New Jersey) scan, in this setting. MATERIALS AND METHODS: A retrospective review was performed of 42 patients undergoing ProstaScint imaging for biochemical progression after radical prostatectomy. Of these patients 16 (38.1%) subsequently completed a course of salvage radiation therapy. RESULTS: Median prostate specific antigen (PSA) immediately prior to ProstaScint imaging was 1.2 ng/ml (range 0.2 to 4.8). Abnormal accumulation on the ProstaScint scan was detected in 36 patients (85.7%). Of the 16 patients undergoing salvage radiation therapy 15 had uptake isolated to the prostatic fossa on ProstaScint imaging. Ten of these 15 patients (66.7%) achieved undetectable PSA after radiation therapy, while 5 (33.3%) had little or no response. Using American Society for Therapeutic Radiology and Oncology criteria 3 of 10 responders had relapse after an average of 9 months. The remaining 7 patients remained biochemically free of disease at last followup. CONCLUSIONS: ProstaScint imaging is capable of detecting recurrent prostate cancer at low PSA levels. However, only 7 of 15 men (46.7%) with ProstaScint uptake isolated to the prostatic fossa showed a durable response to salvage radiation therapy. Based on these findings patients might be better treated based on the rate of increase in PSA rather than on routine scanning with this test.

Aged↗

Critical review of complementary therapies for prostate cancer.

Despite its prominence as the most frequently diagnosed solid tumor among men in the United States, relatively little is known about the etiology of prostate cancer. Furthermore, research into treatment strategies for prostate cancer continues to lag behind research for the other most common cancers. At the same time, however, the popularity of complementary therapies among prostate cancer patients continues to grow. In this article, we provide a critical review of the most recent evidence for dietary modifications, food supplements, and herbs in prostate cancer prevention and treatment. Despite encouraging data for some of these interventions, even the strongest proponents of complementary therapy agree that only randomized controlled trials can provide sufficient evidence on which to create universal guidelines. However, such trials are highly complex and expensive, and they require lengthy follow-up. Until such trials are completed, an opportunity exists for health care professionals to improve their knowledge and understanding of the current evidence for or against complementary therapy in prostate cancer.

Antineoplastic Agents, Phytogenic↗

Surgical resection of a solitary plasmacytoma originating in a rib of a patient with Castleman's disease.

Castleman's disease is a rare disorder characterized by lymphoid hyperplasia. It may present as asymptomatic involvement of one lymph node group or as a multicentric disease with systemic features. We report a patient with Castleman's disease who presented with axillary lymphadenopathy associated with a solitary plasmacytoma originating from a rib. The affected rib was surgically resected and radical radiotherapy was subsequently administered to the axillary lymph nodes. In this particular case, a joint surgical and oncologic approach resulted in a successful outcome.

Adult↗

Educating African-American men about prostate cancer: impact on awareness and knowledge.

OBJECTIVES: To determine whether an education program on prostate cancer could improve awareness and knowledge among African-American men. African-American men have the world's highest incidence of prostate cancer and more than twice the mortality compared with white men. Screening programs for prostate cancer have not been successful in attracting African-American participation. One explanation is a poor awareness and knowledge about the disease among this high-risk population. METHODS: We surveyed 900 African-American adults attending prostate cancer education seminars in community settings throughout Illinois between March 1998 and January 2001. Participants were asked to complete a multiple-choice questionnaire on topics related to prostate cancer. The main outcome measures were a change in awareness and knowledge of prostate cancer after the 1-hour educational seminar. RESULTS: The mean survey score improved from 26.0% before the seminar to 73.3% after it (P <0.0001). Every multiple-choice question was answered correctly more often after the seminar than before it. Increasing levels of education and income were associated with higher before and after scores (P <0.001). Men achieved a significantly greater score improvement (mean 48.1%) compared with women (mean 41.1%; P = 0.006). Previous screening for prostate cancer was reported by 23% of the participants. Using logistic regression analyses, higher levels of education and income correlated with higher rates of screening. After the seminar, 63.1% stated the intention to undergo screening. CONCLUSIONS: Our results demonstrate that prostate cancer awareness and knowledge can improve dramatically after a 1-hour seminar on the topic. Additional studies to evaluate the long-term retention of knowledge and impact on behavior are warranted.

Adult↗

Attitudes and use of complementary medicine in men with prostate cancer.

PURPOSE: Patients with cancer are increasingly incorporating complementary therapies into the overall treatment. We determine the prevalence and patterns of use of complementary therapies among patients with prostate cancer. MATERIALS AND METHODS: Patients attending 6 urology institutions for prostate cancer management completed a self-administered questionnaire on complementary therapy. All men diagnosed with prostate cancer were eligible, regardless of age, stage of disease or treatment. RESULTS: A total of 1,099 patients returned the questionnaire. The overall response rate was 78.5%. Complementary therapies had previously been or were currently being used by 23.5% (258) and 18.2% (200) of patients, respectively. Higher levels of education and income were associated with greater use of complementary therapy (p <0.002 by logistic regression). Patients with progressive disease or those primarily treated with hormones were most likely to use complementary therapy. Among the patients using complementary therapy 90% believed that it would help them live longer and improve quality of life, 60% believed it would relieve symptoms and 47% expected it to cure disease. CONCLUSIONS: Complementary therapies are used by a large number of patients with prostate cancer, particularly those with progressive disease or who have undergone multiple treatments. Health care providers need to recognize this growing pattern of use of complementary therapy. Among patients who use complementary therapy the perception of benefit is much greater than that supported by scientific data. Future research should aim to unravel the complex psychosocial dynamics that influence the decision to use complementary therapy by men with prostate cancer and to educate patients about the efficacy of such therapies.

Aged↗