Longitudinal evaluation of cytogenetic aberrations in prostatic cancer: tumours that recur in time display an intermediate genetic status between non-persistent and metastatic tumours

LIM kinase 1 is essential for the invasive growth of prostate epithelial cells: implications in prostate cancer

Mammalian LIM kinase 1 (LIMK1) is involved in reorganization of actin cytoskeleton through inactivating phosphorylation of the ADF family protein cofilin, which depolymerizes actin filaments. Maintenance of the actin dynamics in an ordered fashion is essential for stabilization of cell shape or promotion of cell motility depending on the cell type. These are the two key phenomena that may become altered during acquisition of the metastatic phenotype by cancer cells. Here we show that LIMK1 is overexpressed in prostate tumors and in prostate cancer cell lines, that the concentration of phosphorylated cofilin is higher in metastatic prostate cancer cells, and that a partial reduction of LIMK1 altered cell proliferation by arresting cells at G2/M, changed cell shape, and abolished the invasiveness of metastatic prostate cancer cells. We also show that the ectopic expression of LIMK1 promotes acquisition of invasive phenotype by the benign prostate epithelial cells. Our data provide evidence of a novel role of LIMK1 in regulating cell division and invasive property of prostate cancer cells and indicate that the effect is not mediated by phosphorylation of cofilin. Our study correlates with the recent observations showing a metastasis-associated chromosomal gain on 7q11.2 in prostate cancer, suggesting a possible gain in LIMK1 DNA (7q11.23).

Genetic evaluation of localized prostate cancer in a cohort of forty patients: gain of distal 8q discriminates between progressors and nonprogressors

Over-representation of sequences on chromosome 7 and 8 have been reported to be associated with aggressive behavior of prostate cancer. In this study we have performed a molecular cytogenetic survey by comparative genomic hybridization of a cohort of 40 prostate cancer patients, consisting of 20 progressors and 20 nonprogressors, after radical surgery for localized adenocarcinoma. Progression was defined as a biochemical relapse, ie, an elevation in prostate-specific antigen level in the serum. The mean follow-up after prostatectomy for the progressor group was 10.6 years, for the nonprogressor group, 9.1 years. Using comparative genomic hybridization, we found that progressors harbored on average more aberrations than nonprogressors. Gains were especially more prominent among progressors (p < 0.05), whereas a statistical trend was detected for losses (p = 0.10). As a consequence we examined all chromosome arms separately. The frequencies of loss for areas known to be frequently deleted in prostate cancer, such as 6q, 8p, or 13q, were not different between the two groups. A tendency was observed for more frequent gain on 3q in the progressor group (p = 0.09). However, gain of 8q (minimal overlapping region at 8q24-qter) was significantly more frequent in the progressor group (p = 0.04). This biomarker retained its significance when adjusted for the factors age, tumor grade, tumor stage, resection margin status, and preoperative prostate-specific antigen level. In conclusion we have created a map of genetic changes in progressive and nonprogressive prostatic carcinomas. Importantly, the presence of gain of distal 8q markedly reduced the progression-free survival, suggesting a clinical role for 8q gain in assessing the malignant potential of localized prostatic adenocarcinoma.

High-resolution analysis of paraffin-embedded and formalin-fixed prostate tumors using comparative genomic hybridization to genomic microarrays

We have used prostate cancer, the most commonly diagnosed noncutaneous neoplasm among men, to investigate the feasibility of performing genomic array analyses of archival tissue. Prostate-specific antigen and a biopsy Gleason grade have not proven to be accurate in predicting clinical outcome, yet they remain the only accepted biomarkers for prostate cancer. It is likely that distinct spectra of genomic alterations underlie these phenotypic differences, and that once identified, may be used to differentiate between indolent and aggressive tumors. Array comparative genomic hybridization allows quantitative detection and mapping of copy number aberrations in tumors and subsequent associations to be made with clinical outcome. Archived tissues are needed to have patients with sufficient clinical follow-up. In this report, 20 formalin-fixed and paraffin-embedded prostate cancer samples originating from 1986 to 1996 were studied. We present a straightforward protocol and demonstrate the utility of archived tissue for array comparative genomic hybridization with a 2400 element BAC array that provides high-resolution detection of both deletions and amplifications.

Gain in chromosome 8q correlates with early progression in hormonal treated prostate cancer

OBJECTIVE

Development and especially hormone refractant progression of prostate cancer are incompletely understood. Clinical studies evaluating genetic aberrations of prior therapy biopsies in correlation with progression data in patients receiving hormone therapy for prostate cancer have not been performed until now.

METHODS

After DNA isolation from histological sections of primary prostate cancer biopsies, comparative genomic hybridization (CGH) was performed according to standard protocols. Primary staging, clinical course and PSA levels of the patients were assessed.

RESULTS

CGH was performed on 28 primary prostate cancer samples. After a mean follow-up of 36 months 11 (39%) of the patients showed progression of disease under hormonal treatment. In patients without and with progression we found the following results, respectively: losses of 6q (41/36%), 8p (41/45%), 16q (23/18%), 18q (30/9%), and gains of 8q (12/64%; P < 0.0001) and 17 (47/26%).

CONCLUSIONS

Gain of 8q is found predominantly in primary core biopsies of local advanced or metastasized prostate cancers. It shows in univariate analysis significant correlation with progression in hormone treated prostate cancer. This fact suggests that gain in 8q represents a marker of aggressiveness in prostate cancer.

Activins and inhibins in endocrine and other tumors

Inhibin and activin are members of the TGF beta superfamily of growth and differentiation factors. They were first identified as gonadal-derived regulators of pituitary FSH and were subsequently assigned multiple actions in a wide range of tissues. More recently, the inhibin alpha subunit was considered as a tumor suppressor based on functional studies employing transgenic mouse models. This review evaluates the functional and molecular evidence that the inhibin alpha subunit is a tumor suppressor in endocrine cancers. The evaluation highlights the discrepant results from the human and mouse studies, as well as the differences between endocrine tumor types. In addition, we examine the evidence that the activin-signaling pathway is tumor suppressive and identify organ-specific differences in the actions and putative roles of this pathway in endocrine tumors. In summary, there is a considerable body of evidence to support the role of inhibins and activins in endocrine-related tumors. Future studies will define the mechanisms by which inhibins and activins contribute to the process of initiation, promotion, or progression of endocrine-related cancers.

Identification of genetic markers for prostatic cancer progression

Despite the high incidence of prostate cancer, only limited data are available on genes or chromosomes specifically involved in its initiation and progression. We have applied comparative genomic hybridization to routinely processed, paraffin-embedded, tissues at different times in prostatic tumor progression to screen the tumor genome for gains and losses. Our panel included specimens derived from 56 different patients: 23 patients with primary, prostate-confined carcinomas; 18 patients with regional lymph node metastases; and 15 patients with distant metastases. Chromosome arms that most frequently showed losses, included 13q (55%), 8p (48%), 6q (43%), 5q (32%), 16q (25%), 18q (20%), 2q (18%), 4q (18%), 10q (18%), and Y (16%). Gains were often seen of chromosome arms 8q (36%), 17q (23%), Xq (23%), 7q (21%), 3q (18%), 9q (18%), 1q (16%), Xp (16%). Furthermore, specific high-level amplifications, eg, of 1q21, 1q25, and Xq12 to q13, were found in metastatic cancers. A significant accumulation of genetic changes in distant metastases was observed, eg, loss of 10q (p = 0.03) and gain of 7q (p = 0.03) sequences. In addition, investigation of a potential biomarker identified in previous studies by our group, ie, extra copies of #7 and/or #8, revealed a high prevalence of 7pq and/or 8q gain in the distant metastases (p = 0.02). Importantly, gains were observed more frequently in tumors derived from progressors after radical prostatectomy, than in nonprogressors (mean time of follow-up, 74 months). Specifically, gain of chromosome 7pq and/or 8q sequences appeared an accurate discriminator between the progressors and nonprogressors. Multivariate analysis showed a significant correlation between progressive disease and the number of chromosomes with gains. This correlation also held true when stage (p = 0.007) or grade (p = 0.002) were taken into account. Likewise, this applied for gain of chromosome 7pq and/or 8q sequences (p = 0.03 and p = 0.005 for stage or grade, respectively). Additionally, an increase in the number of chromosomes with gains per case was related to a decrease in biochemical progression-free survival (Ptrend <0.001). More specifically, the gain of 7pq and/or 8q sequences markedly reduced the biochemical progression-free survival (p < 0.001). In conclusion, this study has, firstly, documented the spectrum of chromosomal alterations in subsequent stages of prostate cancer, a number of which had not been described previously. It allowed us to identify chromosomal regions related to advanced tumor stage, ie, loss of 10q24 and gain of 7q11.2 and/or 7q31 sequences. Secondly, gain of 7pq and/or 8q was identified as a potential genetic discriminator between progressors and nonprogressors after radical surgery.

Detection of extraprostatic prostate cells utilizing reverse transcription-polymerase chain reaction

This article reviews the utility of reverse transcription-polymerase chain reaction (RT-PCR) in prostate cancer. RT-PCR aims to detect occult micrometastases in non-prostatic sites. Due to its exquisite analytical sensitivity, RT-PCR is able to amplify and detect even low-level, prostate-specific messages present at these extraprostatic sites. In recent years, a fair amount of data on the clinical utility of the technique had been reported. The target tissues under investigation are peripheral blood, bone marrow aspirate, and lymph nodes. Favorite markers of choice are prostate-specific antigen (PSA), prostate-specific membrane antigen (PSMA), and human glandular kallikrein-2 (hK2). False positives among negative controls are low. For the most part, RT-PCR is inadequate in detecting tumor cells in the peripheral blood from patients who are known to have metastatic prostate cancer. All studies showed that RT-PCR could detect PSA, PSMA or hK2 mRNAs in the circulation of patients who have organ-confined or extraprostatic disease. Most studies showed that RT-PCR utilizing current markers could not be used as a prospective test to diagnose prostate cancer. However, a few studies also showed that the detection rate could be predictive and sensitive enough to differentiate patients with organ-confined disease from those with extraprostatic disease. Data from PSA- or PSMA-RT-PCR using lymph nodes as the tissue source is more encouraging. RT-PCR was able to detect PSA and/or PSMA positive samples that have not been detected by conventional pathology.