Immunoreactivity for prostate specific antigen and Ki67 differentiates subgroups of prostate cancer related to outcome.

Based on gene-expression profiles, prostate tumors can be subdivided into subtypes with different aggressiveness and response to treatment. We investigated if similar clinically relevant subgroups can be identified simply by the combination of two immunohistochemistry markers: one for tumor cell differentiation (prostate specific antigen, PSA) and one for proliferation (Ki67). This was analyzed in men with prostate cancer diagnosed at transurethral resection of the prostate 1975-1991 (n = 331) where the majority was managed by watchful waiting. Ki67 and PSA immunoreactivity was related to outcome and to tumor characteristics previously associated with prognosis. Increased Ki67 and decreased PSA were associated with poor outcome, and they provided independent prognostic information from Gleason score. A combinatory score for PSA and Ki67 immunoreactivity was produced using the median PSA and Ki67 levels as cut-off (for Ki67 the upper quartile was also evaluated) for differentiation into subgroups. Patients with PSA low/Ki67 high tumors showed higher Gleason score, more advanced tumor stage, and higher risk of prostate cancer death compared to other patients. Their tumor epithelial cells were often ERG positive and expressed higher levels of ErbB2, phosphorylated epidermal growth factor receptor (pEGF-R) and protein kinase B (pAkt), and their tumor stroma showed a reactive response with type 2 macrophage infiltration, high density of blood vessels and hyaluronic acid, and with reduced levels of caveolin-1, androgen receptors, and mast cells. In contrast, men with PSA high/Ki67 low tumors were characterized by low Gleason score, and the most favorable outcome amongst PSA/Ki67-defined subgroups. Men with PSA low/Ki67 low tumors showed clinical and tumor characteristics intermediate of the two groups above. A combinatory PSA/Ki67 immunoreactivity score identifies subgroups of prostate cancers with different epithelial and stroma phenotypes and highly different outcome but the clinical usefulness of this approach needs to be validated in other cohorts.

Prostate cancer increases hyaluronan in surrounding nonmalignant stroma, and this response is associated with tumor growth and an unfavorable outcome.

Our objective was to investigate whether the presence of a tumor increases hyaluronan (HA) levels in surrounding prostate tissues and whether this extratumoral HA influences tumor growth and outcome. From a series of 287 men diagnosed with prostate cancer at transurethral resection and followed up with watchful waiting, tissue microarrays were constructed, stained, and scored for HA. A high HA staining score in the tumor stroma or in nonmalignant prostate tissue stroma were both associated positively with higher Gleason score and larger tumor volume, and was associated with a poor outcome. HA staining score was not an independent marker for outcome (multivariate Cox, with Gleason score, tumor volume, stage, and HA variables). In an orthotopic rat prostate cancer model, hyaluronic acid synthase-1 mRNA levels and HA staining were increased in normal prostate tissue surrounding prostate cancer. Orthotopic prostate cancer growth was increased by intraprostatic injection of HA. In conclusion, cancer in the prostate apparently stimulates HA synthesis both in tumor stroma and in the surrounding normal tissue. This promoted tumor growth and was associated with an unfavorable outcome.

Low endoglin vascular density and Ki67 index in Gleason score 6 tumours may identify prostate cancer patients suitable for surveillance.

OBJECTIVE: The aim of this study was to explore whether vascular density and tumour cell proliferation are related to the risk of prostate cancer death in patients managed by watchful waiting. MATERIAL AND METHODS: From a consecutive series of men diagnosed with prostate cancer at transurethral resection in 1975-1990, tissue microarrays (TMAs) were constructed. A majority of men had no metastases at diagnosis and were followed by watchful waiting (n = 295). The TMAs were stained for Ki67, endoglin and factor VIII-related antigen (vWf). RESULTS: In univariate Cox analyses, increased Ki67 index, endoglin vascular density and vWf vascular density were associated with shorter cancer-specific survival. Ki67 index and endoglin vascular density added independent prognostic information to clinical stage, estimated tumour size and Gleason score (GS) in multivariate Cox analysis. In GS 6 tumours, high Ki67 index and high endoglin vascular density identified patients with poor outcome. After 15 years of follow-up not a single man out of 34 men with low staining for both markers (35% of all GS 6 tumours) had died of prostate cancer, in contrast to 15 prostate cancer deaths among the remaining 63 men with GS 6 tumours (65% cumulative risk of prostate cancer death). vWf vascular density in benign areas was a prognostic marker in GS 6 and 7 tumours. CONCLUSIONS: Men with GS 6 tumours with both low Ki67 index and endoglin vascular density staining scores have a low risk of progression. Additional studies are needed to test whether these two markers can be applied to core biopsies to select patients suitable for surveillance.

LRIG1 and the liar paradox in prostate cancer: a study of the expression and clinical significance of LRIG1 in prostate cancer.

The course of prostate cancer varies greatly, and additional prognostic markers are needed. Leucine-rich repeats and immunoglobulin-like domains protein 1 (LRIG1) is an endogenous inhibitor of growth factor signaling and a proposed tumor suppressor. Publicly available gene expression datasets indicate that LRIG1 may be overexpressed in prostate cancer. In our study, the expression of LRIG1 protein in prostate cancer was evaluated for the first time. Immunohistochemistry was performed on tissue microarrays from two different patient series: 355 Swedish patients diagnosed by transurethral resection and 293 American patients who underwent radical prostatectomy. In the Swedish series, high expression of LRIG1 correlated with Gleason score, T-stage, tumor cell proliferation, vascular density and epidermal growth factor receptor (EGFR) phosphorylation. Among the 256 Swedish patients, followed by watchful waiting, high LRIG1 expression was significantly associated with short overall and prostate cancer-specific survival. In contrast, in the US series, high LRIG1 expression was significantly associated with long overall survival. In vitro cell experiments showed that LRIG1 was induced by androgen stimulation, and its expression inhibited prostate cancer cell proliferation. Thus, LRIG1 expression was an independent marker for poor survival in the untreated patient series, perhaps as a secondary marker of androgen receptor and/or EGFR activation. On the contrary, LRIG1 was a marker for good prognosis after prostatectomy, which might be due to its growth inhibiting properties. We propose that LRIG1 is an important determinant of prostate cancer growth, and the implications of its expression on patient outcome depend on the clinical and biological circumstances.

Mast cells are novel independent prognostic markers in prostate cancer and represent a target for therapy.

Mast cells affect growth in various human tumors, but their role in prostate cancer (PC) is unclear. Here, we identify mast cells as independent prognostic markers in PC using a large cohort of untreated PC patients with a long follow-up. By analyzing mast cells in different tissue compartments, our data indicate that intratumoral and peritumoral mast cells have anti- opposed to protumor properties. Intratumoral mast cells negatively regulate angiogenesis and tumor growth, whereas peritumoral mast cells stimulate the expansion of human prostate tumors. We also observed mast cell recruitment particularly to the peritumoral compartment in men during the formation of castrate-resistant prostate tumors. In our ortothopic rat model, mast cells accumulated in the peritumoral tissue where they enhanced angiogenesis and tumor growth. In line with this, prostate mast cells expressed high levels of the angiogenic factor FGF-2. Similar to the situation in men, mast cells infiltrated rat prostate tumors that relapsed after initially effective castration treatment, concurrent with a second wave of angiogenesis and an up-regulation of FGF-2. We conclude that mast cells are novel independent prognostic markers in PC and affect tumor progression in animals and patients. In addition, peritumoral mast cells provide FGF-2 to the tumor micro environment, which may contribute to their stimulating effect on angiogenesis.

Downstaging and survival benefits of neoadjuvant radiotherapy before cystectomy for patients with invasive bladder carcinoma.

OBJECTIVE: To compare the long-term outcomes of a series of patients treated with neoadjuvant radiotherapy combined with cystectomy against a later series of patients treated with immediate cystectomy. MATERIAL AND METHODS: A total of 187 consecutive patients, surgically treated with cystectomy due to cT1-3 transitional cell bladder carcinoma with (n=90) or without (n=97) neoadjuvant radiotherapy, was included in a retrospective analysis. The clinical stage at the primary bladder resection and the pathological reports after the cystectomy were re-evaluated and progression-free, disease-specific and overall survival were calculated. RESULTS: Seven of 97 (7%) patients treated without any neoadjuvant therapy had pT0 in the bladder specimen. In contrast, 51 of 90 patients (57%) treated with neoadjuvant radiotherapy downstaged to pT0. Among cT3 tumours none of 16 patients (0%) treated without radiotherapy downstaged to pT0, while 19 (56%) of 34 patients treated with radiotherapy did so. The progression-free survival was significantly longer for patients with pT0 than for those with a remaining tumour (pT1-4) in the cystectomy specimen (p<0.001). A high T stage correlated with adverse overall survival. Patients with cT3 tumours treated with neoadjuvant radiotherapy followed by cystectomy had significantly longer disease-specific survival time (p=0.007) than those undergoing cystectomy only. In a Cox regression analysis, cT stage as well as pT stage and occurrence of carcinoma in situ in the cystectomy specimens remained as independent prognostic factors. CONCLUSIONS: In this retrospective study neoadjuvant radiotherapy before the cystectomy resulted in significant downstaging of invasive bladder transitional cell carcinoma. This downstaging was most significant for patients with cT3 tumours leading to prolonged survival.

A single instillation of epirubicin after transurethral resection of bladder tumors prevents only small recurrences.

PURPOSE: We studied whether a single instillation of epirubicin after transurethral bladder tumor resection would influence the interval to and size of the first recurrence. MATERIALS AND METHODS: A total of 404 patients from 13 hospitals were randomized to 1 instillation of 50 mg epirubicin or placebo within 6 hours after transurethral resection of bladder tumors. RESULTS: Of 155 evaluable patients in the epirubicin group 79 (51.0%) had recurrence compared to 95 of 152 (62.5%) in the placebo group (p = 0.04). Of the recurrences 63.3% were small (1 to 5 mm). Tumor size was unknown in 5 patients. Of 79 patients with recurrence in the epirubicin arm 33 (42.9%) vs 29 (31.5%) of 95 in the placebo arm had larger (more than 5 mm) first recurrences (p = 0.12). Approximately half of the patients with first recurrences were treated as outpatients and the other half spent a total of 145 days in the hospital with no difference between the groups. CONCLUSIONS: We confirmed the results of previous studies showing that 8.5 patients must be treated with a single instillation to prevent 1 recurrence. Furthermore, our data may indicate that only small recurrences are prevented, which could easily be fulgurated using local anesthesia at followup cystoscopy. The benefit of single instillations can be questioned if this finding is confirmed by others.

High Caveolin-1 Expression in Tumor Stroma Is Associated with a Favourable Outcome in Prostate Cancer Patients Managed by Watchful Waiting.

In the present study we have investigated whether Caveolin-1 expression in non-malignant and malignant prostate tissue is a potential prognostic marker for outcome in prostate cancer patients managed by watchful waiting. Caveolin-1 was measured in prostate tissues obtained through transurethral resection of the prostate from 395 patients diagnosed with prostate cancer. The majority of the patients (n = 298) were followed by watchful waiting after diagnosis. Tissue microarrays constructed from malignant and non-malignant prostate tissue were stained with an antibody against Caveolin-1. The staining pattern was scored and related to clinicopathologic parameters and outcome. Microdissection and qRT-PCR analysis of Cav-1 was done of the prostate stroma from non-malignant tissue and stroma from Gleason 3 and 4 tumors. Cav-1 RNA expression was highest in non-malignant tissue and decreased during cancer progression. High expression of Caveolin-1 in tumor stroma was associated with significantly longer cancer specific survival in prostate cancer patients. This association remained significant when Gleason score and local tumor stage were combined with Caveolin-1 in a Cox regression model. High stromal Caveolin-1 immunoreactivity in prostate tumors is associated with a favourable prognosis in prostate cancer patients managed by watchful waiting. Caveolin-1 could possibly become a useful prognostic marker for prostate cancer patients that are potential candidates for active surveillance.

Castration radiosensitizes prostate cancer tissue by impairing DNA double-strand break repair.

Chemical castration improves responses to radiotherapy in prostate cancer, but the mechanism is unknown. We hypothesized that this radiosensitization is caused by castration-mediated down-regulation of nonhomologous end joining (NHEJ) repair of DNA double-strand breaks (DSBs). To test this, we enrolled 48 patients with localized prostate cancer in two arms of the study: either radiotherapy first or radiotherapy after neoadjuvant castration treatment. We biopsied patients at diagnosis and before and after castration and radiotherapy treatments to monitor androgen receptor, NHEJ, and DSB repair in verified cancer tissue. We show that patients receiving neoadjuvant castration treatment before radiotherapy had reduced amounts of the NHEJ protein Ku70, impaired radiotherapy-induced NHEJ activity, and higher amounts of unrepaired DSBs, measured by γ-H2AX foci in cancer tissues. This study demonstrates that chemical castration impairs NHEJ activity in prostate cancer tissue, explaining the improved response of patients with prostate cancer to radiotherapy after chemical castration.

High Lysyl Oxidase (LOX) in the Non-Malignant Prostate Epithelium Predicts a Poor Outcome in Prostate Cancer Patient Managed by Watchful Waiting.

Lysyl oxidase (LOX) has been shown to both promote and suppress tumor progression, but its role in prostate cancer is largely unknown. LOX immunoreactivity was scored in prostate tumor epithelium, tumor stroma and in the tumor-adjacent non-malignant prostate epithelium and stroma. LOX scores in tumor and non-malignant prostate tissues were then examined for possible associations with clinical characteristics and survival in a historical cohort of men that were diagnosed with prostate cancer at transurethral resection and followed by watchful waiting. Men with a low LOX score in the non-malignant prostate epithelium had significantly longer cancer specific survival than men with a high score. Furthermore, LOX score in non-malignant prostate epithelium remained prognostic in a multivariable analysis including Gleason score. LOX score in prostate tumor epithelium positively correlated to Gleason score and metastases but was not associated with cancer survival. LOX score in tumor and non-malignant prostate stroma appeared unrelated to these tumor characteristics. In radical prostatectomy specimens, LOX immune-staining corresponded to LOX in-situ hybridization and LOX mRNA levels were found to be similar between tumor and adjacent non-malignant areas, but significantly increased in bone metastases samples. LOX levels both in tumors and in the surrounding tumor-bearing organ are apparently related to prostate cancer aggressiveness.

Improving the Specificity of Screening for Lethal Prostate Cancer Using Prostate-specific Antigen and a Panel of Kallikrein Markers: A Nested Case-Control Study.

BACKGROUND: A disadvantage of prostate-specific antigen (PSA) for the early detection of prostate cancer (PCa) is that many men must be screened, biopsied, and diagnosed to prevent one death. OBJECTIVE: To increase the specificity of screening for lethal PCa at an early stage. DESIGN, SETTING, AND PARTICIPANTS: We conducted a case-control study nested within a population-based cohort. PSA and three additional kallikreins were measured in cryopreserved blood from a population-based cohort in Västerbotten, Sweden. Of 40379 men providing blood at ages 40, 50, and 60 yr from 1986 to 2009, 12542 men were followed for >15 yr. From this cohort, the Swedish Cancer Registry identified 1423 incident PCa cases, 235 with distant metastasis. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Risk of distant metastasis for different PSA levels and a prespecified statistical model based on the four kallikrein markers. RESULTS AND LIMITATIONS: Most metastatic cases occurred in men with PSA in the top quartile at age 50 yr (69%) or 60 yr (74%), whereas 20-yr risk of metastasis for men with PSA below median was low (≤0.6%). Among men with PSA >2 ng/ml, a prespecified model based on four kallikrein markers significantly enhanced the prediction of metastasis compared with PSA alone. About half of all men with PSA >2 ng/ml were defined as low risk by this model and had a ≤1% 15-yr risk of metastasis. CONCLUSIONS: Screening at ages 50-60 yr should focus on men with PSA in the top quartile. A marker panel can aid biopsy decision making. PATIENT SUMMARY: For men in their fifties, screening should focus on those in the top 10% to 25% of PSA values because the majority of subsequent cases of distant metastasis are found among these men. Testing of four kallikrein markers in men with an elevated PSA could aid biopsy decision making.

TMPRSS2-ERG expression predicts prostate cancer survival and associates with stromal biomarkers.

The TMPRSS2-ERG gene fusion is found in approximately half of all prostate cancers. The functional and prognostic significance of TMPRSS2-ERG is, however, not fully understood. Based on a historical watchful waiting cohort, an association between TMPRSS2-ERG, evaluated as positive immune staining, and shorter survival of prostate cancer patients was identified. Expression of ERG was also associated with clinical markers such as advanced tumor stage, high Gleason score, presence of metastasis and prognostic tumor cell markers such as high Ki67, pEGFR and pAkt. Novel associations between TMPRSS2-ERG and alterations in the tumor stroma, for example, increased vascular density, hyaluronan and PDGFRß and decreased Caveolin-1, all known to be associated with an aggressive disease, were found. The present study suggests that the TMPRSS2-ERG fusion gene is associated with a more aggressive prostate cancer phenotype, supported by changes in the tumor stroma.

High density of S100A9 positive inflammatory cells in prostate cancer stroma is associated with poor outcome.

PURPOSE: To elucidate if the density of inflammatory cells expressing S100A9 in malignant and surrounding non-malignant prostate tissues is a prognostic marker for outcome in prostate cancer patients. EXPERIMENTAL DESIGN: Tissue was obtained from 358 men diagnosed with prostate cancer at transurethral resection of the prostate due to obstructive voiding problems, of which 260 were then followed with watchful waiting. Tissue microarrays of both malignant and non-malignant tissues were stained with an antibody against S100A9. The number of stained inflammatory cells was scored and related to clinical outcome and histopathological parameters of known prognostic value. RESULTS: A high number of inflammatory cells expressing S100A9 in both malignant and surrounding non-malignant tissues were associated with significantly shorter cancer-specific survival. This association remained significant when Gleason score and local tumour stage were analysed together with S100A9 in a Cox regression model. Low number of S100A9 positive cells in non-malignant stroma was correlated to significantly longer cancer-specific survival also in patients with Gleason score 8-10 tumours. S100A9 positive cells in tumour stroma were correlated with Gleason score, hyaluronan, platelet-derived growth factor receptor beta (PDGFR-ß), and androgen receptor (inverse correlation) in tumour stroma. S100A9 positive cells in non-malignant stroma correlated with androgen receptor in this tissue compartment (inverse correlation). CONCLUSIONS: A high number of S100A9 positive inflammatory cells in tumour stroma and in non-malignant stroma were associated with shorter cancer-specific survival in prostate cancer patients.

ErbB2 receptor immunoreactivity in prostate cancer: relationship to the androgen receptor, disease severity at diagnosis and disease outcome.

BACKGROUND: ErbB2 is a member of the epidermal growth factor family of tyrosine kinases that is centrally involved in the pathogenesis of prostate cancer and several studies have reported that a high expression of this protein has prognostic value. In the present study, we have investigated whether tumour ErbB2 immunoreactivity (ErbB2-IR) has clinically useful prognostic value, i.e. that it provides additional prognostic information to that provided by routine clinical tests (Gleason score, tumour stage). METHODOLOGY/PRINCIPAL FINDINGS: ErbB2-IR was measured in a well-characterised tissue microarray of tumour and non-malignant samples obtained at diagnosis. Additionally, mRNA levels of ErbB2-IR in the prostate were determined in the rat following manipulation of circulating androgen levels. Tumour ErbB2-IR was significantly associated with the downstream signalling molecule phosphorylated-Akt and with the cell proliferation marker Ki-67. The significant association of tumour ErbB2-IR with the Gleason score at diagnosis was lost when controlled for the association of both parameters with Ki-67. In the rat prostate, mRNA for ErbB2 was inversely associated with circulating androgen levels. There was no association between ErbB2-IR and the androgen receptor (AR)-IR in the tumours, but an interaction between the two parameters was seen with respect to their association with the tumour stage. Tumour ErbB2-IR was confirmed to be a prognostic marker for disease-specific survival, but it did not provide significant additive information to the Gleason score or to Ki-67. CONCLUSIONS/SIGNIFICANCE: It is concluded that tumour ErbB2-IR is of limited clinical value as a prognostic marker to aid treatment decisions, but could be of pathophysiological importance in prostate cancer.

Castration therapy results in decreased Ku70 levels in prostate cancer.

PURPOSE: Neoadjuvant castration improves response to radiotherapy of prostate cancer. Here, we determine whether castration therapy impairs nonhomologous end-joining (NHEJ) repair of DNA double-strand breaks (DSB) by downregulating Ku70 protein expression. EXPERIMENTAL DESIGN: Twenty patients with locally advanced prostate cancer were enrolled, and 6 to 12 needle core biopsy specimens were taken from the prostate of each patient before treatment. Bilateral orchidectomy was conducted in eight patients and 12 patients were treated with a GnRH agonist. After castration, two to four similar biopsies were obtained, and the levels of Ku70 and γ-H2AX foci were determined by immunofluorescence in verified cancer tissues. RESULTS: We observed that the androgen receptor binds directly to Ku70 in prostate tissue. We also found a reduction of the Ku70 protein levels in the cell nuclei in 12 of 14 patients (P < 0.001) after castration. The reduction in Ku70 expression correlated significantly with decreased serum prostate-specific antigen (PSA) levels after castration, suggesting that androgen receptor activity regulates Ku70 protein levels in prostate cancer tissue. Furthermore, a significant correlation between the reductions of Ku70 after castration versus changes induced of castration of γ-H2AX foci could be seen implicating a functional linkage of decreased Ku70 levels and impaired DNA repair. CONCLUSIONS: Castration therapy results in decreased levels of the Ku70 protein in prostate cancer cells. Because the Ku70 protein is essential for the NHEJ repair of DSBs and its downregulation impairs DNA repair, this offers a possible explanation for the increased radiosensitivity of prostate cancer cells following castration.

Nuclear Stat5a/b predicts early recurrence and prostate cancer-specific death in patients treated by radical prostatectomy.

There is an urgent need for reliable markers to identify patients whose prostate cancer (PCa) will recur after initial therapy and progress to lethal disease. Gleason score (GS) is considered the most accurate predictive marker for disease-specific mortality after primary treatment of localized PCa. Most PCas cluster into groups of GS 6 and 7 with considerable variation in the disease recurrence and disease-specific death. In preclinical PCa models, Stat5a/b promotes PCa growth and progression. Stat5a/b is critical for PCa cell viability in vitro and for tumor growth in vivo and promotes metastatic dissemination of cancer in nude mice. Here, we analyzed the predictive value of high nuclear Stat5a/b protein levels in 2 cohorts of PCas: Material I (n = 562) PCas treated by radical prostatectomy (RP), and Material II (n = 106) PCas treated by deferred palliative therapy. In intermediate GS PCas treated by radical prostatectomy, high levels of nuclear Stat5a/b predicted both early recurrence (univariable analysis; P < .0001, multivariable analysis; HR = 1.82, P = .017) and early PCa-specific death (univariable analysis; P = .028). In addition, high nuclear Stat5a/b predicted early disease recurrence in both univariable (P < .0001) and multivariable (HR = 1.61; P = .012) analysis in the entire cohort of patients treated by RP regardless of the GS. Patients treated by deferred palliative therapy, elevated nuclear Stat5a/b expression was associated with early PCa-specific death by univariable Cox regression analysis (HR = 1.59; 95% CI = [1.04, 2.44]; P = .034). If confirmed in future prospective studies, nuclear Stat5a/b may become a useful independent predictive marker of recurrence of lethal PCa after RP for intermediate GS PCas.

Castration therapy of prostate cancer results in downregulation of HIF-1α levels.

BACKGROUND AND PURPOSE: Neoadjuvant androgen deprivation in combination with radiotherapy of prostate cancer is used to improve radioresponsiveness and local tumor control. Currently, the underlying mechanism is not well understood. Because hypoxia causes resistance to radiotherapy, we wanted to test whether castration affects the degree of hypoxia in prostate cancer. METHODS AND MATERIALS: In 14 patients with locally advanced prostate cancer, six to 12 prostatic needle core biopsy specimens were taken prior to castration therapy. Bilateral orchidectomy was performed in 7 patients, and 7 were treated with a GnRH-agonist (leuprorelin). After castrationm two to four prostatic core biopsy specimens were taken, and the level of hypoxia-inducible factor-1α (HIF-1α) in cancer was determined by immunofluorescence. RESULTS: Among biopsy specimens taken before castration, strong HIF-1α expression (mean intensity above 30) was shown in 5 patients, weak expression (mean intensity 10-30) in 3 patients, and background levels of HIF-1α (mean intensity 0-10) in 6 patients. Downregulation of HIF-1α expression after castration was observed in all 5 patients with strong HIF-1α precastration expression. HIF-1α expression was also reduced in 2 of 3 patients with weak HIF-1α precastration expression. CONCLUSIONS: Our data suggest that neoadjuvant castration decreases tumor cell hypoxia in prostate cancer, which may explain increased radiosensitivity after castration.

Phospho-Akt immunoreactivity in prostate cancer: relationship to disease severity and outcome, Ki67 and phosphorylated EGFR expression.

BACKGROUND: In the present study, we have investigated the prognostic usefulness of phosphorylated Akt immunoreactivity (pAkt-IR) in prostate cancer using a well-characterised tissue microarray from men who had undergone transurethral resection due to lower urinary tract symptoms. METHODOLOGY/PRINCIPAL FINDINGS: pAkt-IR in prostate epithelial and tumour cells was assessed using a monoclonal anti-pAkt (Ser(473)) antibody. Immunoreactive intensity was determined for 282 (tumour) and 240 (non-malignant tissue) cases. Tumour pAkt-IR scores correlated with Gleason score, tumour Ki67-IR (a marker of cell proliferation) and tumour phosphorylated epidermal growth factor receptor (pEGFR)-IR. For cases followed with expectancy, a high tumour pAkt-IR was associated with a poor disease-specific survival, and the prognostic information provided by this biomarker was additive to that provided by either (but not both) tumour pEFGR-IR or Ki67-IR. Upon division of the cases with respect to their Gleason scores, the prognostic value of pAkt-IR was seen for patients with Gleason score 8-10, but not for patients with Gleason score 6-7. CONCLUSIONS/SIGNIFICANCE: Tumour pAkt-IR is associated with both disease severity and disease-specific survival. However, its clinical use as a biomarker is limited, since it does not provide prognostic information in patients with Gleason scores 6-7.