[18F]‐fluorocholine positron‐emission/computed tomography for lymph node staging of patients with prostate cancer: preliminary results of a prospective study

Study Type – Diagnostic (case series)
Level of Evidence 4

OBJECTIVES

To evaluate prospectively [¹⁸F]‐fluorocholine positron‐emission/computed tomography (FCH PET/CT) for lymph node staging of prostate cancer before intended curative therapy, and to determine whether imaging 15 or 60 min after radiotracer injection is preferable.

PATIENTS AND METHODS

In all, 25 consecutive patients with newly diagnosed prostate cancer (Gleason score >6, and/or a prostate‐specific antigen level of >10 ng/mL, and/or T3 cancer) were scanned before lymphadenectomy. Each patient was assessed twice with imaging, at 15 and 60 min after the injection with FCH. Images were compared with the results of histopathological examination of the surgically removed lymph nodes. Maximum standardized uptake values (SUV_max) at 15 and 60 min were also compared.

RESULTS

Histopathologically, metastases were present in removed lymph nodes from three patients. FCH PET/CT showed a high radiotracer uptake in four patients, the former three and a fourth. The sensitivity, specificity, positive and negative predictive value of FCH PET/CT for patient based lymph node staging of prostate cancer were 100%, 95%, 75% and 100%, respectively; the corresponding 95% confidence intervals were 29.2–100%, 77.2–99.9%, 19.4–99.4% and 83.9–100%, respectively. Values of SUV_max at early and late imaging were not significantly different.

CONCLUSIONS

This small series supports the use of FCH PET/CT as a tool for lymph node staging of patients with prostate cancer. Values of SUV_max at early and late imaging did not differ. However, larger prospective studies are needed to validate these findings.     

Relaxin becomes upregulated during prostate cancer progression to androgen independence and is negatively regulated by androgens

BACKGROUND: Relaxin is a potent peptide hormone normally secreted by the prostate. This study characterized relaxin expression during prostate cancer progression to androgen independence (AI), and in response to androgens. METHODS: The prostate cancer cell line, LNCaP, was assayed by microarrays and confirmatory Northern analysis to assess changes in relaxin levels due to androgen treatment and in LNCaP xenografts following castration. Relaxin protein levels were examined by immunohistochemistry (IHC) in tissue microarrays of human prostate cancer samples following androgen ablation. RESULTS: Relaxin levels decreased in a time and concentration-dependent manner due to androgens in vitro, and increased in xenografts post-castration. Relaxin increased in radical prostatectomy specimens after 6 months of androgen ablation and in AI tumors, was highest in bone metastases. CONCLUSIONS: Relaxin is negatively regulated by androgens in vitro and in vivo, which correlates to clinical prostate cancer specimens following androgen ablation. The role of relaxin in angiogenesis and tissue remodeling suggests it may contribute to prostate cancer progression.     

Human prostate cancer cells and xenografts are targeted and destroyed through luteinizing hormone releasing hormone receptors

BACKGROUND: A conjugate of a lytic peptide, hecate, and a 15-amino acid segment of the beta-chain of chorionic gonadotropin (CG) destroyed human prostate xenografts in nude mice by targeting LH receptors. Since these xenografts also express LHRH receptors, we prepared a LHRH-hecate conjugate and tested its ability to destroy PC-3 cells in vitro and in vivo. MATERIALS AND METHODS: LHRH-hecate was added to cultures of PC-3, BRF 41 T, DU145, and LNCaP cells in the presence and absence of steroids. PC-3 xenografts were established in nude male mice, which were treated with LHRH-hecate. RESULTS: Injections of LHRH-hecate resulted in tumor growth arrest and marked reduction of tumor burden (62.2 mg/g body weight in saline controls vs. 10.5 mg/g body weight in treated mice; P < 0.0001); unconjugated LHRH and hecate had no effect on tumor burden and tumor viability (48.5 mg/g body weight in LHRH treated animals vs. 63.2 mg/g body weight in hecate treated mice). Marked tumor necrosis occurred in conjugate treated mice. Removal of steroids from the culture media decreased the sensitivity of LNCaP and PC-3 cells to the LHRH-hecate; adding estrogen restored the sensitivity. CONCLUSIONS: LHRH-hecate may be effective in treating hormone dependent and independent prostate cancers.     

Monomethylated selenium inhibits growth of LNCaP human prostate cancer xenograft accompanied by a decrease in the expression of androgen receptor and prostate-specific antigen (PSA)

OBJECTIVES: Epidemiological studies and prevention trials suggest selenium is a promising preventive agent for prostate cancer. Selenium-containing compounds inhibited the growth of prostate cancer cell lines including androgen sensitive LNCaP and androgen insensitive DU145 and PC3 cells in vitro. Previous study revealed a novel mechanism of selenium action in which selenium (methylseleninic acid (MSA)) markedly reduced androgen receptor (AR) signaling in prostate cancer cells, suggesting that selenium might act as an antiandrogen, which could serve as a therapeutic agent for prostate cancer. In this study, we tested whether selenium (methylselenocysteine (MSC)) affects tumor growth of human prostate cancer cells by targeting AR signaling in vivo. METHODS: Prostate tumor xenografts were established in nude mice by co-inoculating LNCaP cells with Matrigel. The mice-bearing tumors were treated with or without MSC (100 microg/mouse/day) via intraperitoneal injection for 2 weeks. The effect of MSC on tumor growth, AR, and prostate-specific antigen (PSA) expression was examined. RESULTS: Methylselenocysteine (MSC) significantly inhibited LNCaP tumor growth (P < 0.05). AR expression in tumor tissues and serum PSA levels were considerably decreased in MSC-treated mice compared to the vehicle controls. CONCLUSIONS: Pharmacological dose of MSC inhibits the growth of LNCaP human prostate cancer in vivo accompanied by a decrease in the expression of AR and PSA. These findings suggest that selenium (MSC) can serve as a therapeutic agent aimed at disruption of AR signaling for prostate cancer.     

The quinoline-3-carboxamide anti-angiogenic agent, tasquinimod, enhances the anti-prostate cancer efficacy of androgen ablation and taxotere without effecting serum PSA directly in human xenografts

PURPOSE: Tasquinimod is a second-generation orally active quinoline-3-carboxamide analog with enhanced potency against prostate cancer via its anti-angiogenic activity. It is presently undergoing clinical trials. Androgen ablation and taxanes are standard therapies for metastatic prostate cancer. This raises the issue of whether combining tasquinimod with either of these approaches enhances therapeutic efficacy. EXPERIMENTAL DESIGN: The tumor growth of a series of human prostate cancer xenografts (CWR-22Rv1, CWR-22R-H, LAPC-4, LNCaP, PC-3 and DU-145) in male nude mice given nothing versus tasquinimod alone or in combination with androgen ablation or with androgen ablation plus taxotere were evaluated as model systems to resolve these issues. RESULTS: These studies documented that daily oral treatment with tasquinimod consistently, statistically (P < 0.05) inhibited the tumor growth of each of the xenografts in a dose-dependent manner via an anti-angiogenic response as monitored by a significant (P < 0.05) decrease in the tumor blood vessel density. Tasquinimod's anti-prostate cancer efficacy is enhanced when combined with androgen ablation and this enhancement was observed even when androgen ablation was either subsequent to or proceeded by tasquinimod treatment. In addition, tasquinimod also enhanced the tumor growth inhibition and survival when combined with androgen ablation plus taxotere. Companion studies documented that tasquinimod has no direct effect on serum PSA in these xenografts. CONCLUSIONS: These results documented that differences in serum PSA in tasquinimod-treated hosts are related to inhibition in tumor growth. This suggests that in clinical trials, changes in PSA slope or doubling time are indicative of therapeutic response to tasquinimod.     

Staging of pelvic lymph nodes in neoplasms of the bladder and prostate by positron emission tomography with 2-[(18)F]-2-deoxy-D-glucose

OBJECTIVES: The aim of this study was to evaluate whether pelvic lymph node metastases in patients with neoplasms of the bladder or prostate can be detected applying positron emission tomography with 2-[(18)F]-2-deoxy-D-glucose (FDG-PET). METHODS: Eight patients with bladder cancer and 17 patients with prostate cancer were examined with FDG-PET before pelvic lymph node dissection. Results of PET were then compared to histology of pelvic lymph nodes obtained at surgery. RESULTS: Lymph node metastases were detected by histopathological examination in 3 patients with bladder cancer and in 6 patients with prostate cancer. At the sites with histologically proven metastases, increased FDG uptake suspicious of metastatic disease was found in 2/3 and 4/6 patients, respectively. The smallest detected metastasis was a micrometastasis with a diameter of 0.9 cm. In 3 additional patients who all had histopathologically proven micrometastases ( 相似文献   

Downregulation of androgen receptor expression by luteolin causes inhibition of cell proliferation and induction of apoptosis in human prostate cancer cells and xenografts

BACKGROUND: Androgen receptor (ARs) play a crucial role in the development and progression of prostate cancer. Recent studies have suggested that prostate cancer cell proliferation is inhibited by AR downregulation. Our aim was to investigate how luteolin, a natural flavonoid, affects cell growth and AR expression in prostate cancer cells and xenografts. METHODS: We assessed prostate cancer cell (LNCaP, DU145, and PC-3) proliferation and apoptosis by MTT assay, flow cytometric analysis, and Western analysis. AR function was measured by evaluating the AR target molecule, prostate-specific antigen (PSA), by RT-PCR, Western blotting, and enzyme-linked immunosorbent assay. We determined the mechanism of AR downregulation with cycloheximide chase assays, proteasome inhibitor, and coimmunoprecipitation experiments. The effects of luteolin on growth inhibition in vivo were examined by LNCaP xenografts in SCID mice. RESULTS: Luteolin significantly repressed prostate cancer cell proliferation and induced apoptosis in LNCaP cells. PC-3 and DU145 cells were less susceptible to luteolin-mediated growth inhibition. Luteolin simultaneously suppressed intracellular and secreted PSA levels and repressed AR mRNA and protein expression in a dose- and time-dependent manner. Luteolin reduced the association between AR and heat-shock protein 90, causing AR degradation through a proteasome-mediated pathway in a ligand-independent manner. Luteolin also suppressed LNCaP xenograft tumor growth in SCID mice. CONCLUSION: Luteolin-mediated AR downregulation contributes to the inhibition of cell proliferation and the induction of apoptosis in LNCaP human prostate cancer cells, suggesting that AR is a molecular target for luteolin-mediated anticancer activity. Luteolin may act as a chemopreventive or chemotherapeutic agent for prostate cancer.     

Calcitriol (1,25-dihydroxycholecalciferol) potentiates activity of mitoxantrone/dexamethasone in an androgen independent prostate cancer model

PURPOSE: Mitoxantrone combined with glucocorticoids is widely used for androgen independent prostate cancer. It is well tolerated, reduces prostate specific antigen, diminishes pain and improves quality of life. Calcitriol (1,25-dihydroxycholecalciferol) inhibits proliferation, modulates cell cycle progression, induces apoptosis and potentiates the cytotoxic effects of a number of agents. Glucocorticoids potentiate the antitumor effects of calcitriol and blunt calcitriol induced hypercalcemia. Therefore, we investigated the effect of calcitriol on the antitumor efficacy of mitoxantrone and dexamethasone or mitoxantrone/dexamethasone in the PC-3 androgen independent prostate cancer model. MATERIALS AND METHODS: We treated PC-3 cells in vitro with various concentrations of mitoxantrone/dexamethasone with and without calcitriol, and assessed growth inhibition by crystal violet assays. We similarly treated mice bearing PC-3 xenografts and performed excision clonogenic assays and tumor outgrowth studies to assess antitumor activity. RESULTS: Calcitriol significantly increased mitoxantrone/dexamethasone mediated growth inhibition in PC-3 cells (p <0.05). Median dose effect analysis indicated that calcitriol is synergistic with mitoxantrone. Adding calcitriol to mitoxantrone/dexamethasone significantly reduced the surviving fraction per gm. tumor compared with mitoxantrone/dexamethasone or untreated controls (p <0.03). Calcitriol plus mitoxantrone/dexamethasone also caused significantly greater tumor regression in PC-3 xenografts compared with treatment with mitoxantrone/dexamethasone or untreated controls (p <0.02). CONCLUSIONS: These preclinical data demonstrate that calcitriol increases the antitumor activity of mitoxantrone/dexamethasone in the PC-3 model system. This combination may be efficacious for prostate cancer.     

Melatonin and prostate cancer cell proliferation: interplay with castration,epidermal growth factor,and androgen sensitivity

BACKGROUND: Potential modulatory effects of melatonin on the proliferation of androgen-sensitive LNCaP and androgen-insensitive PC-3 and DU 145 prostate cancer cells were reported recently. In this study, we investigated the effects of combined melatonin and castration on LNCaP tumor growth in vivo, the interactions between melatonin and epidermal growth factor (EGF) on LNCaP cell proliferation, and melatonin actions on the proliferation of PC-3 and DU 145 cells. METHODS: Tumor development and growth in castrated nude mice inoculated with LNCaP cells or in intact animals inoculated with DU 145 cells, with or without daily melatonin treatment, were monitored by observation and caliper measurement. MT(1) receptor expression in native or transfected prostate cancer cell lines was examined by immunocytochemistry or 2-[(125)I]iodomelatonin binding. Cyclin D1 expression in LNCaP cells was assessed by Western blotting, and cell proliferation was measured by thymidine incorporation and/or cell count. RESULTS: Melatonin treatment was associated with further decreases in LNCaP tumor incidence and growth rate in castrated nude mice. Melatonin and 2-iodomelatonin (a melatonin receptor agonist) attenuated EGF-stimulated increases in LNCaP cell proliferation and cyclin D1 levels. Melatonin had no effect on the proliferation or growth of MT(1) receptor-expressing DU 145 cells, and of PC-3 cells in which MT(1) receptor protein was undetectable. The proliferation of transfected PC-3 cells expressing MT(1) receptor was unaffected by 2-iodomelatonin. CONCLUSION: Together with previous data, the present results indicate synergistic action of melatonin and castration in inhibiting the growth of androgen-sensitive LNCaP tumor. Androgen-sensitive prostate cancer cell proliferation may be modulated by opposite changes in cyclin D1 levels induced by activated MT(1) and EGF receptors. In androgen-insensitive prostate cancer cells, MT(1) receptor-mediated signal transduction may become defective not only through changes in membrane receptor protein expression and/or functions, but also by means of alterations in downstream postreceptor signaling events.     

Inhibition of androgen-sensitive LNCaP prostate cancer growth in vivo by melatonin: association of antiproliferative action of the pineal hormone with mt1 receptor protein expression

BACKGROUND: Potential involvement of the mt1 receptor in the antiproliferative action of melatonin on androgen-sensitive LNCaP cells, and melatonin-induced modulation of androgen-insensitive PC-3 cell growth, have been reported in vitro. The effects of melatonin on prostate cancer cell proliferation and their association with mt1 receptor expression were investigated in athymic nude mice xenograft models of LNCaP and PC-3 cells. METHODS: Daily saline or melatonin (4 microg/g body weight) was given to nude mice before or after tumor cell inoculation. Tumor volume was measured periodically, and expression of PCNA, cyclin A, PSA, and mt1 receptor was assessed by immunohisto(cyto)chemistry and/or Western blotting. RESULTS: Melatonin inhibited the growth of LNCaP tumors, without affecting the growth of PC-3 xenografts, in nude mice. It induced significant decreases in the expression of PCNA, cyclin A, and PSA in LNCaP tumors. Expression of mt1 receptor protein was demonstrated in LNCaP cells, but not in PC-3 cells, both in vivo and in vitro. CONCLUSIONS: The antiproliferative action of melatonin on LNCaP tumor growth was demonstrated in vivo, and its association with mt1 receptor protein expression suggests the potential involvement of the receptor in the antitumor activity of the pineal gland hormone.     

Determinants of diagnostic performance of [F-18]fluorodeoxyglucose positron emission tomography for axillary staging in breast cancer

OBJECTIVE: To prospectively investigate determinants of the accuracy of staging axillary lymph nodes in breast cancer using [F-18]fluorodeoxyglucose positron emission tomography (FDG PET). METHODS: Patients with primary operable breast cancer underwent FDG PET of the chest followed by sentinel node biopsy (SNB, n = 47) and/or complete axillary lymph node dissection (ALND, n = 23). PET scans were independently interpreted by three observers in a blinded fashion with respect to the FDG avidity of the primary tumor and the axillary status. The results were compared to histopathological analyses of the axillary lymph nodes. Clinicians were blinded to the PET results. RESULTS: Axillary lymph node specimens and FDG PET scans were evaluated in 70 patients (59% cT1). Overall, 32 (46%) had lymph node metastases as established by SNB (18/47) or ALND (14/23), 20 of which were confined to a single node. The overall sensitivity of FDG PET was 25%, with a specificity of 97%. PET results were false-negative in all 18 positive SNBs and true-positive in 8/14 in the ALND group. The performance of FDG PET depended on the axillary tumor load and the FDG avidity of the primary tumor. Intense uptake in the primary tumor was found in only 57% of the patients, and this was independent of the size. There was excellent interobserver agreement of visual assessment of FDG uptake in primary tumor and axillary lymph nodes. CONCLUSIONS: The sensitivity of FDG PET to detect occult axillary metastases in operable breast cancer was low, and it was a function of axillary tumor load and FDG avidity of the primary tumor. Even though the clinical relevance of occult disease detected by SNB needs to be confirmed, it is suggested that FDG PET in these patients should be focused on exploiting its nearly perfect specificity and the potential prognostic relevance of variable FDG uptake.     

C16 ceramide accumulates following androgen ablation in LNCaP prostate cancer cells

BACKGROUND: Adenocarcinoma of the prostate is the most frequently diagnosed non-cutaneous cancer and the second leading cause of cancer-related deaths among men in the United States. The most successful therapies to date for this tumor have involved some form of androgen ablation. However, these therapies become ineffective as the tumor evolves to an androgen-insensitive state. Ceramide is a lipid second messenger that has been shown to mediate growth arrest or cell death when added exogenously to prostate cancer cells. As a first step toward understanding the events that lead to the transition of prostate cancer cells to an androgen-independent state, we considered investigating the effect of androgen ablation on endogenous ceramide levels in androgen-sensitive and androgen-insensitive prostate cancer cells. METHODS: To investigate the mechanisms of growth arrest/apoptosis in androgen-sensitive (LNCaP) and insensitive (DU-145, PC-3) cells, we used various methods including nonyl acridine orange (NAO) staining, propidium iodide (PI) staining/cell-cycle analysis, lipid analysis, and Western blotting assays. RESULTS: In this study, we demonstrate that androgen ablation drives G(0)/G(1)-phase cell-cycle arrest followed by progressive apoptosis in vitro, in LNCaP cells. Lipid analysis indicated an increase in C16 ceramide, which was generated via the de novo pathway as revealed by blockade of ceramide synthase by fumonisin B1. The addition of 5alpha-dihydrotestosterone (DHT) or fumonisin B1 rescued LNCaP cells from apoptosis induced by androgen ablation, and decreased levels of intracellular C16 ceramide. Neither apoptosis nor an increase in C16 ceramide was observed in androgen-independent cell lines following androgen ablation.     

Targeted destruction of androgen-sensitive and -insensitive prostate cancer cells and xenografts through luteinizing hormone receptors

BACKGROUND: We have prepared a conjugate of a lytic peptide (hecate) and a 15-amino acid segment of the beta-chain of LH to test the concept that this conjugate will target cancer cells expressing LH receptors. METHODS: Hecate-betaLH was added in vitro to cultures of Chinese hamster ovary (CHO) cells with and without LH receptors and to prostate cancer cells in the presence or absence of steroids, follicle-stimulating hormone (FSH), epidermal growth factor (EGF), or betaLH. PC-3 xenografts were established in male athymic nude mice and treated once a week for 3 weeks with hecate-betaLH via the lateral tail vein. RESULTS: The conjugate showed concentration-dependent toxicity for the following prostate cancer cell lines: BRF 41 T>DU145>PC-3>LNCaP, according to their LH receptor capacities. Steroid removal reduced sensitivity to the drug in a reversible manner. Hecate-betaLH reduced the tumor burden in the nude mice from 60 to 12.5 mg/g body weight. CONCLUSIONS: We conclude that the hecate-betaLH conjugate selectively kills androgen-dependent and-independent prostate cancer cells both in vivo and in vitro; its toxicity depends on the number of LH receptor sites present.     

Stable expression of full length human androgen receptor in PC-3 prostate cancer cells enhances sensitivity to retinoic acid but not to 1alpha,25-dihydroxyvitamin D3

BACKGROUND: PC-3 prostate cancer cell growth is inhibited by 1alpha,25-dihydroxyvitamin D(3) (1,25 D) and retinoids, but not to the same extent as the androgen receptor (AR) positive LNCaP prostate cancer cells. Previous reports suggest a role for AR in growth inhibition of LNCaP cells by 1,25 D and retinoids. PC-3 cells do not express AR. We therefore asked whether re-expression of AR would enhance the response of PC-3 cells to 1,25 D and retinoids. METHODS: PC-3 cells were stably transfected with wild type human AR cDNA. Pooled cells expressing AR protein at levels comparable to LNCaP cells were used to analyze response to 1,25 D, retinoids, androgens, and anti-androgens. RESULTS: AR re-expression in PC-3 cells restored response to androgens and anti-androgens, but growth inhibition by 1,25 D was not significantly altered. However, cells were sensitized to low levels of retinoids, and, in contrast to the parental PC-3 cells, sub-optimal levels of 1,25 D and retinoids caused additive growth inhibition. CONCLUSIONS: Restoring AR expression and activity in PC-3 cells results in enhanced sensitivity to low levels of retinoids while the response to 1,25 D remains unaltered. Thus, the involvement of AR in prostate cancer growth inhibition by 1,25 D appears to be cell line specific.