Inhibition of tumor growth and progression of LNCaP prostate cancer cells in athymic mice by androgen and liver X receptor agonist

Androgen-dependent human LNCaP 104-S tumor xenografts progressed to androgen-independent relapsed tumors (104-Rrel) in athymic mice after castration. The growth of 104-Rrel tumors was suppressed by testosterone. However, 104-Rrel tumors adapted to androgen and regrew as androgen-stimulated 104-Radp tumors. Androgen receptor expression in tumors and serum prostate-specific antigen increased during progression from 104-S to 104-Rrel but decreased during transition from 104-Rrel to 104-Radp. Expression of genes related to liver X receptor (LXR) signaling changed during progression. LXRalpha, LXRbeta, ATP-binding cassette transporter A1 (ABCA1), and sterol 27-hydroxylase decreased during progression from 104-S to 104-Rrel. These coordinated changes in LXR signaling in mice during progression are consistent with our previous findings that reduction of ABCA1 gene expression stimulates proliferation of LNCaP cells. To test if attenuation of LXR signaling may enhance prostate cancer progression from an androgen-dependent state to an androgen-independent state, castrated mice carrying 104-S tumors were given the synthetic LXR agonist T0901317 by gavage. T0901317 delayed progression from 104-S to 104-Rrel tumors. Based on our in vivo model, androgen is beneficial for the treatment of androgen-independent androgen receptor-rich prostate cancer and modulation of LXR signaling may be a potentially useful therapy for prostate cancer.     

Antiproliferative effects of AVN944, a novel inosine 5-monophosphate dehydrogenase inhibitor, in prostate cancer cells

Inosine 5-monophosphate dehydrogenase II, a key enzyme in the de novo synthesis of purine nucleotides, is expressed in prostate tumors and prostate cancer cells. AVN944 is a new, specific, noncompetitive IMPDH inhibitor. In this study, we investigated the effects of IMPDH inhibitor AVN944 on LNCaP, CWR22Rv1, DU145 and PC-3 human prostate cancer cells. AVN944 inhibited proliferation of these 4 prostate cancer cell lines and was associated with cell cycle G1 arrest of LNCaP cells and S-phase block of androgen-independent CWR22Rv1, DU145 and PC-3 cells. AVN944 induced caspase-dependentand caspase-independent cell death in LNCaP, CWR22Rv1, and DU145 cells. AVN944 induced expression of p53-target proteins Bok, Bax and Noxa in androgen-responsive cell lines and suppressed expression of survivin in prostate cancer cells regardless of their androgen sensitivity. AVN944 also induced differentiation of androgen-independent prostate cancer cells as indicated by morphological changes and increased expression of genes coding for prostasomal proteins, keratins and other proteins, including tumor suppressor genes MIG-6 and NDRG1. AVN944-differentiated androgen-independent DU145 and PC-3 cells are sensitized to TRAIL-induced apoptosis as demonstrated by induction of caspases and PARP cleavage. In summary, AVN944 inhibited the growth of human prostate cancer cells by inducing cell cycle arrest, cell death as well as differentiation. AVN944 is a novel, promising therapeutic agent that might be combined with other agents for treatment of human prostate cancer.     

Peroxisome proliferator-activated receptor-γ and growth inhibition by its ligands in prostate cancer

Background: Peroxisome proliferator-activated receptor-γ (PPAR-γ) is expressed in certain human cancers. Ligand-induced PPAR-γ activation can result in growth inhibition and differentiation in these cancer cells; however, the precise mechanism for the anti-proliferative effect of PPAR-γ ligands is not clear. Methods: In this study, we examined the expression of PPAR-γ in human prostate cancer and the effect of two PPAR-γ ligands, 15 deoxy-Δ^12,14-prostaglandin J2 (15d-PGJ2) and troglitazone, on prostate cancer cell growth. Results: PPAR-γ is frequently over-expressed in androgen independent prostate cancer cell lines and human prostate cancer tissues (22 of 47; 47%). Both 15d-PGJ2 and troglitazone inhibited proliferation and DNA synthesis of prostate cancer cell lines in a dose-dependent manner, and slightly increased the proportion of cells with S-phase DNA content. Prostate specific antigen (PSA) promoter reporter assays showed that troglitazone and 15d-PGJ2 down-regulated androgen stimulated reporter gene activity in prostate cancer cell lines LNCaP. Interestingly, LNCaP with troglitazone dramatically suppressed PSA protein expression without suppressing AR expression. Conclusions: Taken together, these results suggest that PPAR-γ ligands may be a useful therapeutic agent for the treatment of prostate cancer.     

Peroxisome proliferator-activated receptor-gamma and growth inhibition by its ligands in prostate cancer

Background: Peroxisome proliferator-activated receptor-γ (PPAR-γ) is expressed in certain human cancers. Ligand-induced PPAR-γ activation can result in growth inhibition and differentiation in these cancer cells; however, the precise mechanism for the anti-proliferative effect of PPAR-γ ligands is not clear. Methods: In this study, we examined the expression of PPAR-γ in human prostate cancer and the effect of two PPAR-γ ligands, 15 deoxy-Δ^12,14-prostaglandin J2 (15d-PGJ2) and troglitazone, on prostate cancer cell growth. Results: PPAR-γ is frequently over-expressed in androgen independent prostate cancer cell lines and human prostate cancer tissues (22 of 47; 47%). Both 15d-PGJ2 and troglitazone inhibited proliferation and DNA synthesis of prostate cancer cell lines in a dose-dependent manner, and slightly increased the proportion of cells with S-phase DNA content. Prostate specific antigen (PSA) promoter reporter assays showed that troglitazone and 15d-PGJ2 down-regulated androgen stimulated reporter gene activity in prostate cancer cell lines LNCaP. Interestingly, LNCaP with troglitazone dramatically suppressed PSA protein expression without suppressing AR expression. Conclusions: Taken together, these results suggest that PPAR-γ ligands may be a useful therapeutic agent for the treatment of prostate cancer.     

Cytoprotective autophagy induction by withaferin A in prostate cancer cells involves GABARAPL1

Withaferin A (WA) is a naturally occurring steroidal lactone with proven cancer chemopreventive activity in preclinical models of different cancers including prostate adenocarcinoma. Previously we compared the RNA-seq data from control and WA-treated 22Rv1 human prostate cancer cells to identify mechanistic targets of this phytochemical. The Gene Ontology pathway analysis of the RNA-seq data revealed significant upregulation of genes associated with autophagy upon WA treatment in 22Rv1 cells. In this study, we extended these findings to investigate the mechanism underlying WA-induced autophagy. Initially, we confirmed autophagy induction by WA treatment by transmission electron microscopy using three prostate cancer cell lines (LNCaP, 22Rv1, and PC-3). Fourteen common genes altered by 8- and 16-hour exposure to WA were identified from human autophagy PCR array and these results were consistent with the RNA-seq data. Two key autophagy markers (LC3BII and SQSTM1) were robustly increased in WA-exposed LNCaP, 22Rv1, and PC-3 cells as determined by immunoblotting, and this effect was elevated in the presence of autophagy inhibitor bafilomycin A1 (BafA1). BafA1 treatment augmented WA's cytotoxicity and subsequently its proapoptotic potential. WA treatment induced GABARAPL1 (ATG8L) protein expression in all three cell lines and its knockdown by RNA interference attenuated WA-mediated apoptosis. WA-induced autophagy was not affected in the presence of an antioxidant (EUK134). Taken together, the present study reveals that WA-mediated autophagy is cytoprotective and mediated by GABARAPL1.     

Inhibition of cell growth and induction of apoptosis in human prostate cancer cell lines by 6-aminoquinolone WM13

Fluoroquinolones affect the proliferation and apoptotic cell death of several human malignancies. Therefore, we investigated whether new 6-aminoquinolone derivatives, initially synthesized as anti-HIV agents, could affect the proliferation and apoptotic cell death of human prostate cancer cell lines. PC3 and LNCaP cell lines were used as models of androgen-resistant and androgen-responsive prostate cancer, and proliferation of PC3 and LNCaP cells was strongly inhibited by 6-aminoquinolone WM13. Cytotoxicity, which was more pronounced in LNCaP, was accompanied by morphological changes, DNA damage, arrest at the S/G(2)/M phase of the cell cycle, and an increase of the sub-G(1) population. Molecular mechanism underlying WM13-induced cell death involved caspase-8 and -3 and modulation of the expression of apoptotic genes, as well as cleavage of poly-ADP ribose polymerase. Cell death following the treatment of human prostate cancer cell lines with WM13 can be attributed to apoptosis which, depending on the cell line, proceeds through different pathways.     

Development of PIN and prostate adenocarcinoma cell lines: a model system for multistage tumor progression

Existing prostate cancer cell lines have been derived from late stages of human prostate cancer. In this paper, we present two cell lines generated from prostatic intraepithelial neoplasia (PIN), the precursor lesion for prostate adenocarcinoma. Pr-111 and Pr-117 were established from PIN lesions that developed in the C3(1)/Tag transgenic model of prostate cancer. Pr-111 and Pr-117 cells express simian virus 40 large T antigen (SV40 Tag) and are immortalized in culture, distinguishing them from normal prostate cells. The growth rates of these two cell lines are quite different; with Pr-111 cells growing much more slowly (doubling time approximately 40 hours) compared to Pr-117 cells (doubling time approximately 22 hours), and also show significantly different growth rates in different media. Both prostate cell lines express cytokeratin and androgen receptor (AR) with Pr-111 cells demonstrating androgen-dependent growth and Pr-117 cells exhibiting androgen-responsive growth characteristics. Athymic nude mice injected with Pr-111 cells either do not develop tumors or develop tumors after a long latency period of 14 weeks. Pr-117 cells, however, develop tumors by 3 to 6 weeks, suggesting that Pr-117 cells represent a later stage of tumor progression. These two novel cell lines will be useful for studying early stages of prostate tumor development and androgen responsiveness.     

Orphan nuclear receptor estrogen-related receptor-beta suppresses in vitro and in vivo growth of prostate cancer cells via p21(WAF1/CIP1) induction and as a potential therapeutic target in prostate cancer

Recent studies indicate that estrogen-related receptors (ERRs) are involved in similar estrogen receptor (ER) regulatory pathways and play roles in energy and lipid metabolism. Here, we analysed the functional role of ERRbeta in prostate cancer cell growth regulation in an androgen-sensitive and androgen-insensitive prostate cancer cell lines. ERRbeta was expressed in normal human prostates, but exhibited a reduced expression in prostate cancer lesions. Stable ERRbeta expression suppressed significantly cell proliferation and tumorigenicity of LNCaP and DU145 cells, accompanied by an S-phase suppression and increased p21 expression. Reporter and chromatin immunoprecipitation assays showed that ERRbeta could directly transactivate p21 gene promoter, which could be further enhanced by peroxisome proliferator-activated receptor-gamma coactivator-1alpha. Truncation analysis showed that ERRbeta-mediated p21 transactivation and prostate cancer cell growth inhibition required intact DNA-binding domain and AF2 domains in ERRbeta. Interestingly, ERRbeta displayed a cell cycle associated downregulated expression pattern in ERRbeta-transduced and non-transduced cells. Finally, we showed that ERRbeta-mediated growth inhibition could be potentiated by an ERRbeta/gamma agonist DY131. Knockdown of ERRbeta by RNA interference could reduce the DY131-induced growth inhibition in prostate cancer cells. Taken together, our findings indicate that ERRbeta performs a tumor suppressing function in prostate cancer cells, and targeting ERRbeta could be a potential therapeutic strategy for prostate cancer.     

Inhibition of mitogen-elicited signal transduction and growth in prostate cancer with a small peptide derived from the functional domain of DOC-2/DAB2 delivered by a unique vehicle

Differentially expressed in ovarian cancer-2/disabled 2 (DOC-2/DAB2) protein, often lost in prostate cancer and other cancer types, is a part of homeostatic machinery in normal prostate epithelium. DOC-2/DAB2 modulates mitogen-elicited mitogen-activated protein kinase (MAPK) signal transduction by sequestering several adaptor or effector molecules, such as growth factor receptor bound protein 2 and c-Src. We have shown that the proline-rich sequence in DOC-2/DAB2 is the key functional domain for this action. In this study, we further synthesized peptide based on the functional proline-rich domain and examined its biological function in prostate cancer using cell-permeable peptide (CPP) as a delivery system. From screening of several CPPs in prostate cancer cell lines, a polyarginine peptide (R11) seemed to be the best delivery vehicle because of its highly efficient uptake. In addition, we also observed a similar in vitro half-life and cellular location of R11 in four different prostate cancer cell lines. By conjugating a proline-rich sequence (PPL) or control sequence (AAL) derived from DOC-2/DAB2 to the COOH terminus of R11, we showed that R11PPL but not R11 or R11AAL was able to suppress either serum- or androgen-induced cell proliferation in prostate cancer cells without endogenous DOC-2/DAB2 expression. Consistently, the activation status of MAPK elicited by these mitogens was significantly inhibited by R11PPL but not by R11AAL or R11. Taken together, we conclude that a functional peptide derived from proline-rich domain in DOC-2/DAB2 has growth-inhibitory activity as its native protein, and CPP seems to be an efficient delivery system in prostate cancer cells.     

Activation of peroxisome proliferator-activated receptor delta stimulates the proliferation of human breast and prostate cancer cell lines

The nuclear receptor peroxisome proliferator-activated receptor delta [PPARdelta/beta (NR1C2)] has been implicated in colorectal carcinogenesis by various molecular genetic observations. These observations have recently been supported by studies of activation of PPARdelta by pharmacological agents. Here we present the first report of the stimulation of breast and prostate cancer cell growth using PPARdelta selective agonists. Activation of PPARdelta with compound F stimulated proliferation in breast (T47D, MCF7) and prostate (LNCaP, PNT1A) cell lines, which are responsive to sex hormones. Conversely, we have found that several steroid-independent cell lines, including colon lines, were unresponsive to compound F. These findings were confirmed with an additional high-affinity PPARdelta agonist, GW501516. Conditional expression of PPARdelta in MCF7 Tet-On cells resulted in a doxycycline-enhanced response to GW501516, thus providing direct genetic evidence for the role of PPARdelta in the proliferative response to this drug. Activation of PPARdelta in T47D cells resulted in increased expression of the proliferation marker Cdk2 and also vascular endothelial growth factor alpha (VEGFalpha) and its receptor, FLT-1, thus, suggesting that PPARdelta may initiate an autocrine loop for cellular proliferation and possibly angiogenesis. Consistent with this hypothesis, we demonstrated a pro-proliferative effect of GW501516 on human umbilical vein endothelial cell cultures and found that GW501516 also regulated the expression of VEGFalpha and FLT-1 in these cells. Our observations provide the first evidence that activation of PPARdelta can result in increased growth in breast and prostate cancer cell lines and primary endothelial cells and supports the possibility that PPARdelta antagonists may be of therapeutic value in the treatment of breast and prostate cancer.     

Bioflavonoids, type II [H-3]estradiol binding sites and prostatic cancer cell proliferation

Previous studies from this laboratory have shown that bioflavonoids including luteolin and quercetin possess antiestrogenic activity in the female reproductive tract and appear to elicit this activity by interaction with type II [H-3]estradiol binding sites in the cell nucleus. Studies by a number of laboratories including our own have shown that type II sites are present in the rodent prostate gland and therefore, we suspected that administration of bioflavonoids such as luteolin may antagonize prostate growth through type LT site binding interactions as well. The studies presented in this report demonstrate that the mouse prostatic tissue does contain nuclear type II sites and that oral administration of luteolin for 14 days results in a significant (p<0.01) reduction in prostatic weight in intact male mice without significant effects on the seminal vesicular, testis or body weights of these animals. These results suggest that luteolin is a prostate specific antagonist under these experimental conditions. In vitro studies with LNCaP and PC-3 human prostate cancer cell lines demonstrated that luteolin treatment resulted in a dose dependent inhibition of prostate cancer cell proliferation which was maximum 4-8 days following treatment. Whole cell binding studies demonstrated that both LNCaP and PC-3 cells contained very high concentrations of type II [H-3]estradiol binding sites (>200,000 sites/cell) relative to levels previously reported for other tissues and cells and luteolin was capable of interacting with these sites in prostate cancer cells. In fact, there was a direct correlation between the type II site occupancy by luteolin and the inhibition of LNCaP or PC-3 prostatic cancer cell proliferation by this bioflavonoid. Flow cytometric analysis revealed that luteolin treatment caused an accumulation of LNCaP cells in G(2)/M (p<0.01) and reduced the fractions of LNCaP cells in S-phase undergoing apoptosis (p<0.01). Similarly, luteolin treatment also arrested PC-3 cells in G(2)/M (p<0.01) and reduced the proportion of cells in G(0)/G(1) (p<0.05). This being the case, it is not surprising that this bioflavonoid also blocked the growth of subcutaneous PC-3 cell xenografts in athymic nude mice. These data demonstrate that naturally occurring type TI site antagonists such as luteolin are capable of inhibiting normal and malignant prostatic cell growth and proliferation in vitro and in viva and may possess prophylactic as well as therapeutic activities against prostatic proliferative diseases including benign prostatic hyperplasia (BPH) and prostate cancer.     

Oncogenic MAP2K1 mutations in human epithelial tumors

The scirrhous subtype of gastric cancer is a highly infiltrative tumor with a poor outcome. To identify a transforming gene in this intractable disorder, we constructed a retroviral complementary DNA (cDNA) expression library from a cell line (OCUM-1) of scirrhous gastric cancer. A focus formation assay with the library and mouse 3T3 fibroblasts led to the discovery of a transforming cDNA, encoding for MAP2K1 with a glutamine-to-proline substitution at amino acid position 56. Interestingly, treatment with a MAP2K1-specific inhibitor clearly induced cell death of OCUM-1 but not of other two cells lines of scirrhous gastric cancer that do not carry MAP2K1 mutations, revealing the essential role of MAP2K1(Q56P) in the transformation mechanism of OCUM-1 cells. By using a next-generation sequencer, we further conducted deep sequencing of the MAP2K1 cDNA among 171 human cancer specimens or cell lines, resulting in the identification of one known (D67N) and four novel (R47Q, R49L, I204T and P306H) mutations within MAP2K1. The latter four changes were further shown to confer transforming potential to MAP2K1. In our experiments, a total of six (3.5%) activating mutations in MAP2K1 were thus identified among 172 of specimens or cell lines for human epithelial tumors. Given the addiction of cancer cells to the elevated MAP2K1 activity for proliferation, human cancers with such MAP2K1 mutations are suitable targets for the treatment with MAP2K1 inhibitors.     

Resveratrol pretreatment desensitizes AHTO-7 human osteoblasts to growth stimulation in response to carcinoma cell supernatants.

Resveratrol, a natural phytoestrogen, has been reported to promote differentiation of murine MC3T3-E1 osteoblasts and to inhibit proliferation of prostate cancer cell lines. In the present study we tested the effects of resveratrol on the increased proliferation of human AHTO-7 osteoblastic cell line induced by conditioned media (CM) from a panel of carcinoma cell lines. This compound was found to modulate AHTO-7 proliferation in a tamoxifen-sensitive mechanism at lower concentrations, but failed to induce the osteoblast differentiation marker alkaline phosphatase (ALP) in contrast to vitamin D3. The proliferative response of AHTO-7 cells to conditioned media from carcinoma cell lines was diminished (30-71.4% inhibition) upon pretreatment with 0.5 microM resveratrol. Highest inhibition was demonstrated for pancreas (BxPC3, Panc-1), breast (ZR75-1) and renal (ACHN) carcinoma cell line supernatants whereas the effect on colon carcinoma (SW620, Colo320DM) cell CM and prostate cancer (PC3, DU145 and LNCaP) CM was less pronounced. Direct addition of resveratrol affected only supernatants of cell lines (<25% inhibition) exhibiting growth stimulatory activity for normal WI-38 lung fibroblasts. Resveratrol inhibited proliferation of DU145 and LNCaP cells in concentrations exceeding 5 microM, altered cell cycle distribution of all prostate cancer cell lines in concentrations as low as 0.5 microM, but did not inhibit the production of osteoblastic factors by these lines. In conclusion, resveratrol failed to induce ALP activity as marker of osteoblast differentiation in human osteoblastic AHTO-7 cells, however, inhibited their response to osteoblastic carcinoma-derived growth factors in concentrations significantly lower than those to reduce growth of cancer cells, thus effectively modulating tumor - osteoblast interaction.     

Neuropeptide Y stimulates proliferation and migration in the 4T1 breast cancer cell line

Stress has long been thought of to be associated with increased risk of cancer. Chronic stress is associated with elevated levels of sympathetic neurotransmitter (norepinephrine and neuropeptide Y: NPY) release and immunosuppression. The expression of NPY receptors has been reported in human breast carcinomas. Recently, activation of the NPY Y5 receptor was shown to stimulate cell growth and increase migration in human breast cancer cells; however the effects of NPY have yet to be investigated in a murine model of breast cancer. Thus, the specific aims of the current study were to: (i) characterize NPY receptor expression in 4T1 breast cancer cells and orthotopic tumors grown in BALB/c mice and (ii) investigate the impact of NPY receptor activation on 4T1 cell proliferation and migration in vitro. Positive expression of NPY receptors (Y1R, Y2R and Y5R) was observed in cells and tumor tissue. As well, NPY treatment of 4T1 cells promoted a concentration-dependent increase in proliferation, through increased phosphorylation of ERK 1/2. Using NPY receptor antagonists (Y1R:BIBP3226, Y2R:BIIE0246 and Y5R:L-152,804), we found the proliferative response to be Y5R mediated. Additionally, NPY increased chemotaxis through Y2R and Y5R activation. These data are in congruence with those from human cell lines and highlight the 4T1 cell line as a translatable model of breast cancer in which the effects of NPY can be studied in an immunocompetent system.     

OSU03012 activates Erk1/2 and Cdks leading to the accumulation of cells in the S-phase and apoptosis

OSU03012, a Celecoxib derivative, has been shown to inhibit proliferation and induce apoptosis in human cancer cell lines. However, its underlying mechanisms are not completely understood. In our study, the relationship between cell cycle inhibition and apoptosis induced by OSU03012 was investigated in human oral cancer cell lines. In the premalignant and malignant cell lines, OSU03012-induced growth inhibition, S-phase arrest, and apoptosis were accompanied by a marked increase in the activity of Erk1/2 and Cdk2/cyclin A. Inhibition of Cdks by roscovitine partially blocked OSU03012-induced growth inhibition and apoptosis. Although the activity of cdc2/cyclin B was reduced, expression of constructively active cdc2AF did not reverse OSU03012-induced S-phase arrest. When Erk1/2 was inhibited by U0126 before addition of OSU03012, growth inhibition and apoptosis induced by OSU03012 were attenuated. The levels of the Cdk2/cyclin A were reduced and cells accumulated in the G(0)/G(1) phase. When cells were allowed to accumulate in S-phase before addition of U0126, apoptosis also was attenuated suggesting that Erk1/2 is required for both progression of cells into the S-phase and apoptosis. Expression of constructively active MEK enhanced OSU03012-induced apoptosis. OSU03012 selectively inhibited the proliferation in premalignant and malignant, but not normal human oral cell lines. In conclusion, we show that OSU03012 has potent anti-proliferative and apoptotic activity against premalignant and malignant human oral cells through activation of Erk1/2, and Cdks. OSU0312 may provide unique opportunities for cancer prevention and sensitization of cancer cells to S-phase modalities.     

Knocking down gene expression for growth hormone-releasing hormone inhibits proliferation of human cancer cell lines

Splice Variant 1 (SV-1) of growth hormone-releasing hormone (GHRH) receptor, found in a wide range of human cancers and established human cancer cell lines, is a functional receptor with ligand-dependent and independent activity. In the present study, we demonstrated by western blots the presence of the SV1 of GHRH receptor and the production of GHRH in MDA-MB-468, MDA-MB-435S and T47D human breast cancer cell lines, LNCaP prostate cancer cell line as well as in NCI H838 non-small cell lung carcinoma. We have also shown that GHRH produced in the conditioned media of these cell lines is biologically active. We then inhibited the intrinsic production of GHRH in these cancer cell lines using si-RNA, specially designed for human GHRH. The knocking down of the GHRH gene expression suppressed the proliferation of T47D, MDA-MB-435S, MDA-MB-468 breast cancer, LNCaP prostate cancer and NCI H838 non-SCLC cell lines in vitro. However, the replacement of the knocked down GHRH expression by exogenous GHRH (1-29)NH(2) re-established the proliferation of the silenced cancer cell lines. Furthermore, the proliferation rate of untransfected cancer cell lines could be stimulated by GHRH (1-29)NH(2) and inhibited by GHRH antagonists MZ-5-156, MZ-4-71 and JMR-132. These results extend previous findings on the critical function of GHRH in tumorigenesis and support the role of GHRH as a tumour growth factor.     

Alteration of glyoxalase genes expression in response to testosterone in LNCaP and PC3 human prostate cancer cells

Glyoxalase system, a ubiquitous detoxification pathway protecting against cellular damage caused by potent cytotoxic metabolites, is involved in the regulation of cellular growth. Aberrations in the expression of glyoxalase genes in several human cancers have been reported. Recently, we described a possible regulatory effect by estrogens on glyoxalase genes in human breast cancer cell lines. This result, along with those ones regarding changes in glyoxalases activity and expression in other human hormone-regulated cancers, such as prostate cancer, has prompted us to investigate whether also androgens, whose functional role in prostate cancer pathogenesis is well known, could modulate glyoxalases gene expression. Therefore, we treated LNCaP androgen-responsive and PC3 androgen-independent human prostate cancer cell lines with testosterone at the concentrations of 1 nM and 100 nM. After a two days treatment, glyoxalases mRNA levels as well as cell proliferation were evaluated by real-time RT-PCR analysis and [3H]thymidine incorporation, respectively. Results pointed out that testosterone affects the expression of glyoxalase system genes and cell proliferation in a different manner in the two cell lines. The possibility that modulation of glyoxalase genes expression by testosterone is due to glyoxalases-mediated intracellular response mechanisms to the androgen-induced oxidative stress or to the presence of androgen response elements (ARE) in glyoxalase promoters are discussed. Knowledge regarding the regulation of glyoxalases by testosterone may provide insights into the importance of these enzymes in human prostate carcinomas in vivo.