BoBafit : A copy number clustering tool designed to refit and recalibrate the baseline region of tumors' profiles.

Human cancer arises from a population of cells that have acquired a wide range of genetic alterations, most of which are targets of therapeutic treatments or are used as prognostic factors for patient's risk stratification. Among these, copy number alterations (CNAs) are quite frequent. Currently, several molecular biology technologies, such as microarrays, NGS and single-cell approaches are used to define the genomic profile of tumor samples. Output data need to be analyzed with bioinformatic approaches and particularly by employing computational algorithms. Molecular biology tools estimate the baseline region by comparing either the mean probe signals, or the number of reads to the reference genome. However, when tumors display complex karyotypes, this type of approach could fail the baseline region estimation and consequently cause errors in the CNAs call. To overcome this issue, we designed an R-package, BoBafit , able to check and, eventually, to adjust the baseline region, according to both the tumor-specific alterations' context and the sample-specific clustered genomic lesions. Several databases have been chosen to set up and validate the designed package, thus demonstrating the potential of BoBafit to adjust copy number (CN) data from different tumors and analysis techniques. Relevantly, the analysis highlighted that up to 25% of samples need a baseline region adjustment and a redefinition of CNAs calls, thus causing a change in the prognostic risk classification of the patients. We support the implementation of BoBafit within CN analysis bioinformatics pipelines to ensure a correct patient's stratification in risk categories, regardless of the tumor type.

Clonal and subclonal TP53 molecular impairment is associated with prognosis and progression in multiple myeloma.

Aberrations on TP53, either as deletions of chromosome 17p (del17p) or mutations, are associated with poor outcome in multiple myeloma (MM), but conventional detection methods currently in use underestimate their incidence, hindering an optimal risk assessment and prognostication of MM patients. We have investigated the altered status of TP53 gene by SNPs array and sequencing techniques in a homogenous cohort of 143 newly diagnosed MM patients, evaluated both at diagnosis and at first relapse: single-hit on TP53 gene, either deletion or mutation, detected both at clonal and sub-clonal level, had a minor effect on outcomes. Conversely, the coexistence of both TP53 deletion and mutation, which defined the so-called double-hit patients, was associated with the worst clinical outcome (PFS: HR 3.34 [95% CI: 1.37-8.12] p = 0.008; OS: HR 3.47 [95% CI: 1.18-10.24] p = 0.02). Moreover, the analysis of longitudinal samples pointed out that TP53 allelic status might increase during the disease course. Notably, the acquisition of TP53 alterations at relapse dramatically worsened the clinical course of patients. Overall, our analyses showed these techniques to be highly sensitive to identify TP53 aberrations at sub-clonal level, emphasizing the poor prognosis associated with double-hit MM patients.

Inhibition of autophagy, lysosome and VCP function impairs stress granule assembly.

Stress granules (SGs) are mRNA-protein aggregates induced during stress, which accumulate in many neurodegenerative diseases. Previously, the autophagy-lysosome pathway and valosin-containing protein (VCP), key players of the protein quality control (PQC), were shown to regulate SG degradation. This is consistent with the idea that PQC may survey and/or assist SG dynamics. However, despite these observations, it is currently unknown whether the PQC actively participates in SG assembly. Here, we describe that inhibition of autophagy, lysosomes and VCP causes defective SG formation after induction. Silencing the VCP co-factors UFD1L and PLAA, which degrade defective ribosomal products (DRIPs) and 60S ribosomes, also impaired SG assembly. Intriguingly, DRIPs and 60S, which are released from disassembling polysomes and are normally excluded from SGs, were significantly retained within SGs in cells with impaired autophagy, lysosome or VCP function. Our results suggest that deregulated autophagy, lysosomal or VCP activities, which occur in several neurodegenerative (VCP-associated) diseases, may alter SG morphology and composition.

Prospective phase II trial of cetuximab plus VMAT-SIB in locally advanced head and neck squamous cell carcinoma. Feasibility and tolerability in elderly and chemotherapy-ineligible patients.

INTRODUCTION: Cetuximab plus radiotherapy (RT) may be an effective alternative to chemoradiation in locally advanced head and neck squamous cell carcinoma (LASCCHN) patients. We analyzed a group of patients treated at our institute with cetuximab plus volumetric modulation arc therapy (VMAT) with the RapidArc technique in a simultaneous integrated boost (SIB) regime. The primary end point was the assessment of acute toxicity and the feasibility of the combined approach. MATERIALS AND METHODS: Between December 2008 and March 2010, 22 patients were submitted to IMRT-SIB plus cetuximab for radical intent in case of LASCCHN. None of the patients was suitable for chemotherapy because of important comorbidities (the majority suffered of heart chronic diseases). All patients underwent planning CT (additional image modalities were acquired for contouring purposes in the same treatment position: MRI in 12 and FDG-PET in 4 out of 22 patients). VMAT, by means of RapidArc, and SIB with two dose levels of 54.45 Gy and 69.96 Gy in 33 fractions were adopted. All patients included in the analysis were concomitantly treated with cetuximab: administration of the drug was initiated 1 week before RT at a loading dose of 400 mg/m(2) body surface area over a period of 120 min, follow by a weekly 60 min infusion of 250 mg/m(2) for the duration of RT. Patients were assessed for toxicities according to the Radiation Therapy Oncology Group (RTOG) criteria. RESULTS: All but 2 patients completed treatment and achieved the minimum follow-up of 12 months after the end of the treatment. Of the 22 patients, 18% (4 patients) showed grade 1, 36% (8 patients) grade 2, and 36% (8 patients) showed grade 3 dermatitis, while 9% (2 patients) had grade 1, 36% (8 patients) grade 2, and 45% (10 patients) had grade 3 mucositis/stomatitis. No grade 4 toxicities were recorded. Considering blood parameters, 3 cases of grade 1 anemia and 1 case of grade 2 thrombocytopenia were observed. Nobody required feeding tube placement during treatment. CONCLUSION: The here reported toxicity data are promising and encouraging in regard to the adoption of moderate hypofractionation with VMAT-SIB techniques, when cetuximab is concomitantly administered.

ASAP1 promotes tumor cell motility and invasiveness, stimulates metastasis formation in vivo, and correlates with poor survival in colorectal cancer patients.

We have previously performed an unbiased screen to identify genes whose expression is associated with the metastatic phenotype. Secondary screening of these genes using custom microarray chips identified ASAP1, a multi-domain adaptor protein with ADP-ribosylation factor-GAP activity, as being potentially involved in tumor progression. Here, we show that at least three different splice forms of ASAP1 are upregulated in rodent tumor models in a manner that correlates with metastatic potential. In human cancers, we found that ASAP1 expression is strongly upregulated in a variety of tumors in comparison with normal tissue and that this expression correlates with poor metastasis-free survival and prognosis in colorectal cancer patients. Using loss and gain of function approaches, we were able to show that ASAP1 promotes metastasis formation in vivo and stimulates tumor cell motility, invasiveness, and adhesiveness in vitro. Furthermore, we show that ASAP1 interacts with the metastasis-promoting protein h-prune and stimulates its phosphodiesterase activity. In addition, ASAP1 binds to the SH3 domains of several proteins, including SLK with which it co-immunoprecipitates. These data support the notion that ASAP1 can contribute to the dissemination of a variety of tumor types and represent a potential target for cancer therapy.

[Angiosarcoma of the nasal cavity. Report of a case and review of the literature]. / Angiosarcoma della cavità nasale. Descrizione di un caso e revisione della letteratura.

We report an unusual case of primary angiosarcoma of the nasal cavity (AS-nc). Clinical--monolateral epistaxis in a young person--, radiological--polypoid hemorrhagic tumor arising within the nasal cavity and expanding into paranasal sinuses--, pathological--a network of anastomosing channels and solid areas immunoreactive for CD31 and CD34--and prognostic features--patient alive and well 36 months after the original diagnosis--are superimposable to those of previously reported AS-nc, suggesting that this lesion should be considered as a peculiar variant of classical AS.

Lepidium meyenii (Maca) does not exert direct androgenic activities.

Maca is the edible root of the Peruvian plant Lepidum meyenii, traditionally employed for its purported aphrodisiac and fertility-enhancing properties. This study aimed at testing the hypothesis that Maca contains testosterone-like compounds, able to bind the human androgen receptor and promote transcription pathways regulated by steroid hormone signaling. Maca extracts (obtained with different solvents: methanol, ethanol, hexane and chloroform) are not able to regulate GRE (glucocorticoid response element) activation. Further experiments are needed to assess which compound, of the several Maca's components, is responsible of the observed in vivo effects.

Androgen-induced neurite outgrowth is mediated by neuritin in motor neurones.

In the brain, the spinal cord motor neurones express the highest levels of the androgen receptor (AR). Experimental data have suggested that neurite outgrowth in these neurones may be regulated by testosterone or its derivative 5alpha-dihydrotestosterone (DHT), formed by the 5alpha-reductase type 2 enzyme. In this study we have produced and characterized a model of immortalized motor neuronal cells expressing the mouse AR (mAR) [neuroblastoma-spinal cord (NSC) 34/mAR] and analysed the role of androgens in motor neurones. Androgens either activated or repressed several genes; one has been identified as the mouse neuritin, a protein responsible for neurite elongation. Real-time PCR analysis has shown that the neuritin gene is expressed in the basal condition in immortalized motor neurones and is selectively up-regulated by androgens in NSC34/mAR cells; the DHT effect is counteracted by the anti-androgen Casodex. Moreover, DHT induced neurite outgrowth in NSC34/mAR, while testosterone was less effective and its action was counteracted by the 5alpha-reductase type 2 enzyme inhibitor finasteride. Finally, the androgenic effect on neurite outgrowth was abolished by silencing neuritin with siRNA. Therefore, the trophic effects of androgens in motor neurones may be explained by the androgenic regulation of neuritin, a protein linked to neurone development, elongation and regeneration.

Relationship of AgNOR counts and nuclear DNA content to survival in patients with parathyroid carcinoma.

The aim of this study was to evaluate the usefulness of DNA flow cytometry to determine tumor nuclear DNA index (DI), and nucleolar organizer region protein counts visualized by the argyrophil (AgNOR) technique, in confirming diagnosis and predicting clinical outcome of patients with parathyroid carcinoma (PC). We reviewed paraffin-embedded tissue sections, from 15 patients (median age 63 years, range 30-68 years) with PC who died of the disease, which were randomly compared with tissue sections from 15 age- and sex-matched patients with parathyroid adenoma (PA). The proliferative activity in parathyroid tumours as detected by DI and AgNOR counts was evaluated in all specimens. Both DI (1.37 +/- 0.33 vs 1.0 +/- 0.1) and AgNOR (3.01 +/- 0.31 vs 1.54 +/- 0.35) counts were higher (P < 0.001) (Student's t-test) in patients with PC than in those with PA. Diploid (DI = 1), aneuploid (DI > 1) and hypoploid (DI < 1) neoplasms were found in 11 (PC = 4, PA = 7), 14 (PC = 11, PA = 3) and five (PC = 0, PA = 5) patients respectively. The average postoperative survival in patients with PC was 46.9 +/- 37.4 months (range 21-146 months). The survivals of patients with aneuploid (n = 11) and diploid (n = 4) PC were 74.0 +/- 58.1 and 34.1 +/- 18.4 months (P=0.21) respectively. There was a significant relationship between DI and AgNOR counts (R=0.69, P < 0.01), but no correlation was found between survival and both DI (Rho = 0.17, P = 0.55) and AgNOR counts (Rho = 0.26, P = 0.35). Moreover, there was no correlation (P = NS) between the main preoperative biochemical parameters and survival. In conclusion, DI and AgNOR are useful in confirming the diagnosis of PC, but they are of little value in predicting the clinical outcome of patients with PC.

Accuracy of fine-needle aspiration cytology and frozen-section examination in patients with thyroid cancer.

In patients with solitary thyroid nodules (TN) undergoing surgery both fine-needle aspiration (FNA) and frozen-section examination (FSE) are currently performed, but their role is still controversial. We retrospectively analyzed a series of 606 patients with a nontoxic solitary thyroid nodule who underwent both FNAB and FSE prior to thyroidectomy. There were 118 (19.5%) men and 488 (80.5%) women, with a median age of 44 years (range 16-81 years). The results of both FNAB and FSE were compared against the final pathological examination. Definitive histology showed 500 (82.5%) benign nodules, including 239 (39.4%) follicular adenomas, and 106 (17.5%) carcinomas, of which 18 (17.0%) were follicular cancer. In differentiating between benign TN and thyroid tumors the sensitivity, specificity, and accuracy of FNAB were 93.6%, 98.9% and 95.9%, while in the detection of malignancy were 81.1%, 99.4% and 96.2% for FNAB, and 83.0%, 100% and 97.0% for FSE (P = NS), respectively. The combination of both techniques did not improve significantly (P = NS) the results. Both medullary and undifferentiated cancer, and 76 of 80 (95.0%) papillary carcinomas were correctly detected by FNAB. Three (0.5%) false-positive smears suggesting cancer were found. In conclusion, in patients with FNAB revealing thyroid cancer or a benign TN, the extent of thyroidectomy should be established by performing FSE. When FNAB suggests the presence of a follicular tumor, FSE may affect rarely the final intraoperative decision-making, and should be considered unnecessary. However, in patients with FNA revealing thyroid cancer, FSE is useful in confirming malignancy, and may avoid surgical overtreatments.

Androgen 5-alpha-reductase type 2 is highly expressed and active in rat spinal cord motor neurones.

Spinal cord motoneurones express high levels of androgen receptor. However, in responsive tissue, the effects of testosterone is often mediated by the more potent androgenic derivative 5-alpha-dihydrotestosterone (DHT). This compound is formed in androgen target cells by the enzyme 5-alpha-reductase. Two isoforms of the 5-alpha-reductase, with limited degree of homology, have been cloned, type 1 and type 2. The low affinity-constitutive type 1 isoenzyme is widely distributed in the body; the high affinity-androgen regulated 5-alpha-reductase type 2 is confined to androgen-dependent structures and shows a peculiar pH optimum at acidic values. We have previously shown that high levels of 5-alpha-reductase activity are detectable in rat spinal cord. Here, using reverse transcriptase-polymerase chain reaction, we show that both isoforms are expressed in the whole spinal cord of the rat. The enzymatic pH optimum measured in immortalized spinal cord motoneurones (NSC34) is typical of the type 2 isoenzyme. Using in situ hybridization technique, we found that 5-alpha-reductase type 2 is confined to the motoneuronal cells of the anterior horns of the rat spinal cord, the cells that also are known to express high levels of androgen receptor. Because of the close association of androgen receptor and 5-alpha alpha-reductase type 2, motoneuronal cells should be considered as target cells for androgens.

Follicular dendritic cell tumor of the mediastinum.

Follicular dendritic cell tumor (FDT) is a rare neoplasm usually occurring in the laterocervical lymph nodes, but presentations elsewhere are also well documented. We report a case of FDT in a 48-year-old man with myasthenia gravis, in whom a slow-growing mediastinal mass that had been surgically excised manifested after 3 years with a local recurrence in the same site. The lesion was aspirated and cytology showed a tumor composed of groups of oval or elongated cells intermingled with several mature small lymphocytes. On histology, the tumor was highly cellular with abundant perivascular lymphocytic infiltration; large cells with pale, eosinophilic cytoplasm and round nuclei, arranged in fascicles often showed a storiform pattern. Occasional binucleated cells were also present. A panel of antibodies showed positivity only for CD21 and CD35, and a weak response to S-100. Electron microscopy showed that the layer cells had convoluted nuclei and elongated interdigitating processes with desmosome-like junctions. The definitive diagnosis of FDT can be concluded only with positive immunostaining for CD21 and CD35. However, in the presence of a mixed population of lymphocytes and larger eosinophilic cells the hypothesis of FDT should always be considered.

Polyglutamine tract expansion of the androgen receptor in a motoneuronal model of spinal and bulbar muscular atrophy.

Spinobulbar muscular atrophy (SBMA) is a late-onset disorder characterized by progressive muscle loss, degeneration of motoneurons in the spinal cord and brainstem, and partial androgen insensitivity. SBMA is directly correlated with the expansion of CAG repeats encoding a polyglutamine tract (polyQ) of extended length. The identification of polyQ expansion in SBMA led to the discovery of an entire class of neurodegenerative disorders. In fact, at least eight different diseases, including Huntington's disease, share a common molecular mechanism involving an expansion of a polyQ tract within different proteins. The elongated polyQ tract causes a toxic gain of function in the mutant protein and is associated with the formation of intracellular aggregates, whose pathogenetic role has not been fully established yet. Our observations in a motoneuron cell line (NSC34), indicate that the expression of the androgen receptor (AR) carrying the elongated polyQ tract (AR-Q48) has a toxic effect in aggregate-independent manner. In fact, in basal condition, AR-Q48 shows a cytoplasmic diffuse distribution, yet it reduces the viability of transfected NSC34. In contrast, testosterone treatment, while inducing aggregation of the mutant AR, also increases cell viability. Aggregates in NSC34 are localized mainly in the perinuclear region and occasionally in the neuropil, whereas no nuclear aggregate has ever been found. Further observations of the minor subset of cells showing neuropil aggregates, reveal an alteration of the neurite morphology, suggesting a different role of the two types of cytoplasmic aggregates.

Expression and role of functional glucocorticoid receptors in the human androgen-independent prostate cancer cell line, DU145.

We investigated the presence of glucocorticoid receptors (GR) as well as the role of glucocorticoids (Gc) in the control of proliferation of the androgen-independent prostate cancer cell line, DU145. We detected the presence of a specific high affinity binding site (K(d) 2.3 nM) for [(3)H]dexamethasone ([(3)H]Dex) in the cytosolic preparations of DU145 cells; the density of these binding sites is significantly higher than that detected in HA22T/VGH and in HepG2, two hepatoma cell lines classically considered models for the study of GR. Immunocytochemistry studies confirmed the presence of GR in the cytosolic compartment of DU145 cells; GR undergo translocation to the nucleus following exposure to dexamethasone (Dex). The functional activity of GR present in DU145 cells was also studied by analyzing the potency of Dex in inducing chloramphenicol acyltransferase (CAT) activity in DU145 cells transfected with a glucocorticoid/progesterone response element (GRE/PRE) tkCAT plasmid (GRE/PREtkCAT plasmid). The results have shown that Dex stimulates the transcriptional activity of GR in transfected DU145 cells with an EC(50) of 9.65 nM and a maximal induction of sevenfold above basal levels. Finally, a dose-dependent (IC(50) 3.14 nM) decrease of DU145 cell numbers was observed after their exposure to Dex for 4 days; this effect was counteracted by the presence of the steroid antagonist, RU486. In conclusion, the present data suggest a possible role of corticoids in the control of the growth of androgen-independent prostate cancer.

5Alpha-reductase type 2 and androgen receptor expression in gonadotropin releasing hormone GT1-1 cells.

Gonadal steroids are potent modulators of gonadotropin releasing hormone (GnRH) secretion, and androgen binding sites and 5alpha-reductase activity have been found in the immortalized GnRH secreting cell line GT1-1, suggesting the existence of a direct androgenic control of GnRH dynamics. Two isoforms of the 5alpha-reductase have been cloned with very different biochemical/functional properties: 5alpha-reductase type 1 (widely distributed in the body) and 5alpha-reductase type 2 (confined in androgen target structures). We have analysed whether, in GT1-1, androgen binding sites are linked to "classical" androgen receptor, and which 5alpha-reductase isoform is active. Reverse transcriptase-polymerase chain reaction analysis showed that the mRNAs coding for androgen receptor and for the two 5alpha-reductase isoforms are all expressed in GT1-1 cells. However, the 5alpha-reductase enzymatic reaction showed a peak of activity at a narrow pH around 5.5, the optimum for the 5alpha-reductase type 2. The affinity for testosterone, of the enzyme present in GT1-1 cells, was very similar to that observed for the recombinant type 2 isozyme expressed in yeasts. The data indicate that GT1-1 cells (i) express a "classical" androgen receptor and (ii) contain the 5alpha-reductase type 2 isoform, a specific marker of androgen-responsiveness.

Role of androgens in proliferation and differentiation of mouse mammary epithelial cell line HC11.

Androgens have been found in mammary epithelium and in milk throughout the cycle of the mammary gland in vivo. The aim of this study was to investigate the possible role of these substances in mammary epithelial growth and differentiation in the mouse HC11 cell line. Cells were stimulated with testosterone, dihydrotestosterone, androstenedione and 5alpha-androstane-3alpha,17beta-diol at concentrations ranging between 0.3 nM and 30 nM. Cyproterone acetate or flutamide, androgen receptor antagonists, (3 microM) were used to block specific androgen effects. Proliferative effects were measured by an MTT (tetrazolium blue) conversion test and [(3)H]thymidine uptake. HC11 cells were transfected with pbetacCAT, a chimeric rat beta-casein gene promoter-chloramphenicol acetyl transferase (CAT) gene construct and CAT ELISA was used to determine gene expression. RT-PCR was performed to detect androgen receptor expression. After 24, 48 and 72 h androgens significantly (P<0.05) increased proliferation. Androgen antagonists significantly (P<0.05) reduced the proliferative effects. Furthermore androgens potentiated the lactogenic effect of prolactin, insulin and dexamethasone (P<0.05). Finally, the androgen receptor gene was expressed in both proliferating and differentiated HC11 cells. These observations lead us to hypothesize an activity of this class of steroids in mammary physiology. In particular, androgens stimulate cell proliferation and beta-casein gene expression; this influence appears to be mediated by androgen receptors.

Co-existence of cutaneous T-cell lymphoma and B hairy cell leukemia.

A primary cutaneous form of peripheral T-cell lymphoma (PTCL) and a low grade B-cell non-Hodgkin's lymphoma that was classified as a variant of hairy cell leukemia (HCL) were simultaneously diagnosed in a 79-year-old woman by both phenotypic and genotypic analyses. The coexistence of a T- and B-cell lymphoma in the same patient is rare, and, to our knowledge, this particular association has not been previously described. The patient was referred to our Department for evaluation of multiple cutaneous itchy, reddish plaques; laboratory analyses disclosed a lymphocytosis, that presented 6 years earlier. A bone marrow aspirate showed a 50% B-cell interstitial infiltrate, while a skin biopsy surprisingly revealed a PTCL. Clonality of both neoplastic processes was assessed by Southern blot analysis. The indolent clinical course of the cutaneous disease, and the low and stable number of circulating neoplastic T cells supported the diagnosis of a mycosis fungoides (MF)-like PTCL. Possible oncogenic events and/or putative underlying viral infections which could have played a role in the occurrence of B- and T-cell non-Hodgkin's lymphomas in the same patient are discussed.

Motoneuronal cell death is not correlated with aggregate formation of androgen receptors containing an elongated polyglutamine tract.

Spinal and bulbar muscular atrophy (SBMA) is associated with an abnormal expansion of the (CAG)(n)repeat in the androgen receptor (AR) gene. Similar mutations have been reported in other proteins that cause neurodegenerative disorders. The CAG-coded elongated polyglutamine (polyGln) tracts induce the formation of neuronal intracellular aggregates. We have produced a model to study the effects of potentially 'neurotoxic' aggregates in SBMA using immortalized motoneuronal cells (NSC34) transfected with AR containing polyGln repeats of different sizes [(AR.Q(n = 0, 23 or 46)]. Using chimeras of AR.Q(n) and the green fluorescent protein (GFP), we have shown that aggregate formation occurs when the polyGln tract is elongated and AR is activated by androgens. In NSC34 cells co-expressing the AR with the polyGln of pathological length (AR.Q46) and the GFP we have noted the presence of several dystrophic neurites. Cell viability analyses have shown a reduced growth/survival rate in NSC34 expressing the AR.Q46, whereas testosterone treatment partially counteracted both cell death and the formation of dystrophic neurites. These observations indicate the lack of correlation between aggregate formation and cell survival, and suggest that neuronal degeneration in SBMA might be secondary to axonal/dendritic insults.

5alpha-reductase isozymes and aromatase are differentially expressed and active in the androgen-independent human prostate cancer cell lines DU145 and PC3.

BACKGROUND: The presence and possible role of androgen-metabolizing enzymes in androgen-independent prostate carcinoma (CaP) are still unclear. The aim of the present study was: 1) to evaluate the pattern of androgen metabolism (relative production of 5alpha-reduced vs. 17-keto androgens); and 2) to analyze whether one or both the two known 5alpha-reductase isoforms (5alpha-R1 and 5alpha-R2) and the aromatase (Aro) are expressed and active in this pathology. METHODS: Two different cell lines (DU145 and PC3) were used as a model of androgen-independent human CaP. In these cells, the expression of the two 5alpha-Rs and of Aro were evaluated by reverse transcription-polymerase chain reaction (RT-PCR) and Southern blot, using specific sets of oligoprimers and of [(32)P]-labeled oligoprobes; the enzymatic activities of 5alpha-R and of Aro were evaluated by radioenzymatic methods. The pH optimum for the activity of the two 5alpha-Rs was assessed in cell homogenates at different pH (from 3.5-8), using substrate concentrations similar either to 5alpha-R1 or to 5alpha-R2 Kms. RESULTS: The two CaP cell lines DU145 and PC3, although unresponsive to androgens, possess the enzymatic machinery involved in the metabolism of this class of hormonal steroids: 5alpha-Rs, which allow their transformation into 5alpha-reduced steroids (5alpha-dihydrotestosterone, DHT, and 5alpha-androstandione, 5alpha-A), and 17beta-hydroxysteroid-oxidoreductase (17beta-HSD), which interconverts testosterone (T) and androstenedione (ADIONE); however, the two cell lines show differences in the rate of formation of these metabolites. Furthermore, two cell lines expressed the type 1 isoform of 5alpha-R, but only DU145 cells also possess 5alpha-R2. Aro is expressed and active in DU145 as well as in PC3 cells. CONCLUSIONS: The present findings suggest that T might still be indirectly active in androgen-unresponsive CaP through its local conversion into estrogens by the action of Aro; the biological role played by the two 5alpha-Rs in androgen-independent CaP deserves further investigation.