Cadmium chloride-induced dysplastic changes in the ventral rat prostate: an immunohistochemical and quantitative study

Sub-chronic cadmium and lead compound exposure induces reproductive toxicity and development of testicular germ cell neoplasia in situ in murine model: Attenuative effects of resveratrol

Cadmium and lead are widespread, nonbiodegradable heavy metals of perpetual environmental concerns. The present study aimed to evaluate whether sub-chronic exposure to cadmium chloride (CdCl₂ ) and lead acetate [Pb(CH₃ COO)₂ ] induces reproductive toxicity and development of testicular germ cell neoplasia in situ (GCNIS) in swiss albino mice. The effects of resveratrol to reverse the metal-induced toxicity were also analyzed. The mice were randomly divided into four groups for metal treatments and two groups received two different doses of each metal, CdCl₂ (0.25 and 0.5 mg/kg) and Pb(CH₃ COO)₂ (3 and 6 mg/kg). The fourth group received oral doses of 20 mg/kg resveratrol in combination with 0.5 mg/kg CdCl₂ or 6 mg/kg Pb(CH₃ COO)₂ for 16 weeks. Toxic effects of both metals were estimated qualitatively and quantitatively by the alterations in sperm parameters, oxidative stress markers, testicular histology, and protein expressions of the treated mice. Pronounced perturbation of sperm parameters, cellular redox balance were observed with severe distortion of testicular histo-architecture in metal exposed mice. Significant overexpression of Akt cascade and testicular GCNIS marker proteins were recorded in tissues treated with CdCl₂ . Notable improvements were observed in all the evaluated parameters of resveratrol cotreated mice groups. Taken together, the findings of this study showed that long-term exposure to Cd and Pb compounds, induced acute reproductive toxicity and initiation of GCNIS development in mice. Conversely, resveratrol consumption abrogated metal-induced perturbation of spermatogenesis, testicular morphology, and the upregulation of Akt cascade proteins along with GCNIS markers, which could have induced the development of testicular cancer.

Dimensional study of prostate cancer using stereological tools

This study analyzes the dimensional changes of the glands from prostate cancer by applying stereology to estimate the variations in volume, length, surface, and cellular densities of tumor acini. Normal and tumor acini were visualized using immunohistochemistry for cytokeratin18. On immunostained sections, parameters related to the dimensions and cell population of prostate acini were measured. The immunohistochemical expression of proliferative cell nuclear antigen was also measured to correlate the quantitative changes estimated with the proliferative activity of the epithelium. The average cell volume in normal and tumor epithelium was estimated using the method of the nucleator. The relative size of the acini was similar in the carcinoma compared with the normal prostate. Within the acini, the fraction of acinar volume occupied by the epithelium was significantly higher in cancer than in the nontumor prostate. Conversely, the glandular lumen of the cancer acini is lower than in the normal acini. The significant increase of acinar length density in the carcinoma indicates that the glandular tree's growth in the carcinoma is higher and with more branches than in the case of nonneoplastic glands. The basal surface density is higher in the carcinoma than in the controls. The number of epithelial cells per unit length of acini was significantly decreased in the neoplastic glands. This "dilution" of the cell population along the cancer acinus can be explained by the significant increase in the tumor cell's mean cell volume.

Long-term effects of perinatal exposure to low doses of cadmium on the prostate of adult male rats

Developmental toxicity caused by environmental exposure to heavy metals during the perinatal period has raised questions about offspring health. Cadmium (Cd) is an endocrine-disrupting chemical with the potential to interfere with morphogenesis and susceptibility to diseases in reproductive organs. Taking into account that in the rat prostate morphogenesis occurs during the perinatal period, and that pregnant females absorb and retain more dietary Cd than their non-pregnant counterparts, it is important to understand the effects of perinatal Cd exposure on the adult rat prostate. Therefore this study investigated the effects of gestational and lactational Cd exposure on adult offspring rat prostate histopathology. Pregnant rats (n = 20) were divided into two groups: Control (treated with aqueous solution of sodium acetate 10 mg/l) and treated (treated with aqueous solution of cadmium acetate 10 mg/l) administered in the drinking water. After weaning, male offspring from different litters (n = 10) received food and water 'ad libitum'. The animals were euthanized at postnatal day 90 (PND90), the ventral prostates (VPs) were removed, weighed and examined histopathologically. Blood was collected for the measurement of testosterone (T) levels. Immunohistochemistry for androgen receptor (AR) and Ki67, and a TUNEL assay were performed. There were no differences in T levels, cell proliferation and apoptosis indexes, or AR immunostaining between the experimental groups. Stromal inflammatory foci and multifocal inflammation increased significantly in the treated group. These changes were associated with inflammatory reactive epithelial atypia and stromal fibrillar rearrangement. In conclusion, VP was permanently affected by perinatal Cd exposition, with increased incidence of inflammatory disorders with ageing.

In silico functional pathway annotation of 86 established prostate cancer risk variants

Heritability is one of the strongest risk factors of prostate cancer, emphasizing the importance of the genetic contribution towards prostate cancer risk. To date, 86 established prostate cancer risk variants have been identified by genome-wide association studies (GWAS). To determine if these risk variants are located near genes that interact together in biological networks or pathways contributing to prostate cancer initiation or progression, we generated gene sets based on proximity to the 86 prostate cancer risk variants. We took two approaches to generate gene lists. The first strategy included all immediate flanking genes, up- and downstream of the risk variant, regardless of distance from the index variant, and the second strategy included genes closest to the index GWAS marker and to variants in high LD (r2 ≥0.8 in Europeans) with the index variant, within a 100 kb window up- and downstream. Pathway mapping of the two gene sets supported the importance of the androgen receptor-mediated signaling in prostate cancer biology. In addition, the hedgehog and Wnt/β-catenin signaling pathways were identified in pathway mapping for the flanking gene set. We also used the HaploReg resource to examine the 86 risk loci and variants high LD (r2 ≥0.8) for functional elements. We found that there was a 12.8 fold (p = 2.9 x 10-4) enrichment for enhancer motifs in a stem cell line and a 4.4 fold (p = 1.1 x 10-3) enrichment of DNase hypersensitivity in a prostate adenocarcinoma cell line, indicating that the risk and correlated variants are enriched for transcriptional regulatory motifs. Our pathway-based functional annotation of the prostate cancer risk variants highlights the potential regulatory function that GWAS risk markers, and their highly correlated variants, exert on genes. Our study also shows that these genes may function cooperatively in key signaling pathways in prostate cancer biology.

Effects of cadmium on cell proliferation, apoptosis, and proto-oncogene expression in zebrafish liver cells

Cadmium (Cd) is one of the major transitional metal that has toxic effects in aquatic organisms and their associated ecosystem; however, its hepatic toxicity and carcinogenicity are not very well characterized. We used a zebrafish liver (ZFL) cell line as a model to investigate the mechanism of Cd-induced toxicity on hepatocytes. Our results showed that Cd can be effectively accumulated in ZFL cells in our exposure experiments. Cell cytotoxicity assays and flow cytometer measurements revealed that Cd(2+) stimulated ZFL cell proliferation with decreasing apoptotic cell numbers indicating potentially tumorigenic effects of Cd in ZFL cells. Gene expression profiles also indicated that Cd downregulated oncogenes p53 and rad51 and upregulated immediate response oncogenes, growth arrest and DNA damage-inducible (gadd45) genes, and growth factors. We also found dramatic changes in the gene expression of c-jun and igf1rb at different exposure time points, supporting the notion that potentially tumorigenic of Cd-is involved in the activation of immediate early genes or genes related to apoptosis in cancer promotion.

Expression of lysophosphatidic acid receptor 1 and relation with cell proliferation, apoptosis, and angiogenesis on preneoplastic changes induced by cadmium chloride in the rat ventral prostate

BACKGROUND

Lysophosphatidic acid (LPA) is a phospholipid growth factor involved in cell proliferation, differentiation, migration, inflammation, angiogenesis, wound healing, cancer invasion, and survival. This study was directed to evaluate the immunoexpression of LPA-1, cell proliferation, apoptosis, and angiogenesis markers in preneoplastic lesions induced with cadmium chloride in rat prostate.

METHODS

The following parameters were calculated in ventral prostate of normal rats and rats that received Cd in drinking water during 24 months: percentages of cells immunoreactive to LPA-1 (LILPA1), PCNA (LIPCNA), MCM7 (LIMCM7), ubiquitin (LIUBI), apoptotic cells (LIAPO), and p53 (LIp53); volume fraction of Bcl-2 (VFBcl-2); and length of microvessels per unit of volume (LVMV/mm3). Data were analyzed using Student's t-test and Pearson correlation test.

RESULTS

The LILPA1 in dysplastic lesions and normal epithelium of Cd-treated rats was significantly higher than those in the control group. Markers of proliferation were significantly increased in dysplastic lesions, whereas some apoptotic markers were significantly decreased. No significant differences between groups were found in VFBcl-2. Dysplastic lesions showed a significant increase of LIp53. The length of microvessels per unit of volume was elevated in dysplastic acini. Statistically significant correlations were found only between LILPA1 and LIUBI.

CONCLUSIONS

Our results suggest that LPA-1 might be implicated in dysplastic lesions induced by cadmium chloride development. More studies are needed to confirm its potential contribution to the disease.

Cadmium down-regulates expression of XIAP at the post-transcriptional level in prostate cancer cells through an NF-kappaB-independent, proteasome-mediated mechanism

Background

Cadmium has been classified as a human carcinogen, affecting health through occupational and environmental exposure. Cadmium has a long biological half-life (>25 years), due to the flat kinetics of its excretion. The prostate is one of the organs with highest levels of cadmium accumulation. Importantly, patients with prostate cancer appear to have higher levels of cadmium both in the circulation and in prostatic tissues.

Results

In the current report, we demonstrate for the first time that cadmium down-regulates expression of the X-linked inhibitor of apoptosis protein (XIAP) in prostate cancer cells. Cadmium-mediated XIAP depletion occurs at the post-transcriptional level via an NF-κB-independent, proteasome-mediated mechanism and coincides with an increased sensitivity of prostate cancer cells to TNF-α-mediated apoptosis. Prolonged treatment with cadmium results in selection of prostate cancer cells with apoptosis-resistant phenotype. Development of apoptosis-resistance coincides with restoration of XIAP expression in cadmium-selected PC-3 cells.

Conclusions

Selection of cadmium-resistant cells could represent an adaptive survival mechanism that may contribute to progression of prostatic malignancies.

Partial hepatectomy, partial portal vein stenosis and mesenteric lymphadenectomy increase splanchnic mast cell infiltration in the rat

It is currently believed that portal hypertension induces an inflammatory response in which mast cells may be involved. The aim of this study was to verify the involvement of the intestinal submucosal and mesenteric lymph node mast cells in the splanchnic inflammatory response related to portal hypertension. Mast cell infiltration in the intestine (duodenum, jejunum, ileum, caecum and distal colon) and in the mesenteric lymph node complex (MLC) was measured using a stereological method in sham-operated rats (SO; n = 12), in two experimental models of portal hypertension, chronic (triple partial portal vein ligation, TPVL; n = 12) and transient (microsurgical partial hepatectomy; n = 12) and in rats in which the MLC was resected (n = 12). The small and large bowel submucosal infiltration increases in MLC-resected rats (p = 0.0001), in TPVL rats (p = 0.0001) and in rats with partial hepatectomy (p = 0.0001). An extensive mast cell infiltration in the MLC (p = 0.0001) was found in TPVL rats and in rats with partial hepatectomy (347.40+/-45.25 and 351.92+/-99.28/mm(3), respectively) in relation to sham-operated rats (135.27+/-30.28/mm(3)). We conclude that mast cells could be involved in the splanchnic alterations developed in the surgical experimental models of portal hypertension studied.

Changes in the number and volume of NPY and VIP neurons from periprostatic accessory vegetative ganglia in pre- and peripubertal rats. A stereological study

The amount of neurons of periprostatic accessory ganglia in pre- and peripubertal rats was studied to ascertain whether the development of these autonomic ganglia is androgen-dependent. Stereological estimates of the volumes and number of neurons immunoreactive to protein gene product 9.5 (PGP 9.5), neuropeptide Y (NPY), and vasoactive intestinal polypeptide (VIP) were carried out. Immunostaining of androgen receptors (AR) in the ganglia was also performed. The ganglionic neurons from the two groups studied were immunoreactive to PGP 9.5, NPY, and VIP. Almost all the neurons were immunostained for AR. The ganglionic volume showed a significant increase in peripubertal prostate in comparison with the prepubertal gland. No significant changes were observed with respect to the absolute number of neurons immunoreactive to all the antigens. The neuronal volume was significantly increased in peripubertal rats in comparison with prepubertal animals. These findings led us to the following conclusions: There is no evidence of neurogenesis during pubertal development in the periprostatic accessory ganglia of the rat. The increase of ganglionic volume in puberty is due to the growth in neuronal volume. There were no differences between the sizes of NPY and VIP neurons in pubertal periprostatic accessory ganglia. The development of periprostatic vegetative neurons is androgen-dependent.

Effect of Prolactin and Bromocriptine on the Population of Prostate Neuroendocrine Cells from Intact and Cyproterone Acetate-Treated Rats: Stereological and Immunohistochemical Study

This work deals with the quantification of serotonin-immunoreactive prostate neuroendocrine cells (NECs) in rats exposed to prolactin in normal, cyproterone acetate-exposed, and bromocriptine-exposed animals to establish the possible influence of prolactin with or without androgenic blockade on this cell population. Thirty male peripubertal Sprague-Dawley rats were grouped as controls (CT) and those treated with cyproterone acetate (CA), cyproterone acetate plus prolactin, cyproterone acetate plus bromocriptine, prolactin (PL), and bromocriptine (BC). The volume of ductal epithelium (Vep) and total number (NSER) of the NECs serotonin-immunoreactive were measured. NECs were detected in the periurethral ducts. Compared to CT, Vep was increased in PL and BC and NSER was decreased in CA and increased in the prolactin or bromocriptine groups. The androgenic blockade decreases NSER in rat prostate; PL induces in normal and cyproterone acetate-treated rats the increase of NSER; and BC exerts a local effect over the prostate similar to that described for PL.

Effects of chronic exposure to cadmium on prostate lipids and morphology

Cadmium is an environmental toxic metal implicated in human prostate carcinogenesis. The mechanism of its toxicity is not fully understood. Previously, we showed that cadmium exposure induces oxidative stress, especially lipid peroxidation. This study evaluates the effect of chronic exposure to 0.886 mM of cadmium (Cd) per liter in the drinking water on prostate lipid content and metabolism in Wistar rats. We determined the lipid profile and measured the expression of lipogenic enzymes: FAS, GPAT, LPL, DGAT-1, DGAT-2, ACO, CPT-1 and CT, and of certain factors involved in lipid regulation and fatty acid transporters: FAT/CD36, E-FABP, SREBP-2, PPAR-gamma and PPAR-alpha by RT-PCR. Ultrastructure was analyzed by electron microscopy and, as prostate is an androgen controlled gland, AR expression was measured by RT-PCR and Western blot. Cd altered the prostatic lipid profile. Triglycerides (TG) and esterified cholesterol (EC) decreased, free cholesterol (FC) and phospholipids (PL) increased and total cholesterol (TC) did not change. FAS, MDH and IDH activities did not vary but G6PDH decreased significantly in Cd group. Regarding TG synthesis, DGAT-1 decreased while GPAT increased and FAS, LPL and DGAT-2 remained unchanged. Regarding beta oxidation, CPT-1 increased while ACO expression decreased in Cd group. In the PL pathway, CT expression was increased. All these results would justify the decrease of TG in Cd group when compared to control. In the cholesterol metabolic pathway, HMGCoAR and SREBP-2 increased. PPAR-alpha increased but PPAR-gamma did not change. Regarding fatty acid transporters, FAT/CD36 decreased, while E-FABP increased. AR mRNA and protein expression decreased. Ultrastructural analysis showed a decrease in lipid droplets and signs of cellular damage in the Cd group. Cadmium exposure induces important changes in prostatic lipid profile and metabolism, confirmed by the morphology analyses, which also showed signs of cellular damage. These results could be important to further understanding the complex mechanism of cadmium toxicity in prostate and in the development of better treatments for people and animals exposed to the heavy metal.

Immunohistochemical study of cell proliferation, Bcl-2, p53, and caspase-3 expression on preneoplastic changes induced by cadmium and zinc chloride in the ventral rat prostate

This work was directed to evaluate immunoexpression of markers for apoptosis, resistance to apoptosis, and cell proliferation, as well as estimates of nuclear size in ventral prostate of rats treated with cadmium chloride and cadmium+zinc chloride because a possible protective effect of zinc has been postulated. The following variables were studied: volume fraction (VF) of Bcl-2 immunostaining, percentage of cells immunoreactive to proliferating cell nuclear antigen (LIPCNA) and p53 (LIp53), numerical density of caspase-3 immunoreactive cells (NV caspase-3), and estimates of volume-weighted mean nuclear volume (upsilonV). The LIPCNA and VF of Bcl-2 were significantly increased in the treated animals. The dysplasias (independent of their origin) showed a significant increase of the LIp53, NV caspase-3, and upsilonV in comparison with normal acini from treated and control animals. It can be concluded that cell proliferation is enhanced in long-term cadmium-exposed rats, and exposure to zinc combined with cadmium had no effect on any of the variables studied when comparing with normal acini. The increase of nuclear upsilonV could indicate a more aggressive behavior for pretumoral lesions.

Cadmium and prostate cancer: a critical epidemiologic analysis

Laboratory data implicate cadmium as a prostate carcinogen. However, epidemiological studies concerning the association between cadmium and prostate cancer are inconclusive. This article reviews the epidemiological literature on cadmium and prostate cancer with a special focus on highly exposed occupational cohorts. We searched the MEDLINE database from 1966 to 2002 for articles on cadmium and prostate cancer. All published analytical and descriptive studies that included relevant data were reviewed. In addition, we reviewed the experience of cohorts highly exposed to cadmium in nickel-cadmium battery plants. Of 4 descriptive studies, 3 reported a positive association between cadmium and prostate cancer. Of 10 case-control studies, 5 (50%) reported a positive association. Of 11 cohorts studies, 3 (33%) found a positive association. Finally, 4 studies on cohorts exposed in occupational nickel-cadmium batteries were identified and analyzed. The summary score of the standardized mortality ratios (SMRs) was weakly but not significantly positive 126 (95% confidence interval C.I.: 83-184). In contrast to laboratory studies, epidemiological studies do not convincingly implicate cadmium as a cause of prostate cancer. Future epidemiological studies that attempt to resolve the discrepancy between laboratory and epidemiological studies of cadmium carcinogenesis may benefit from incorporating biological measures of cadmium exposure.

Quantitative and immunohistochemical evaluation of PCNA, androgen receptors, apoptosis, and Glutathione-S-Transferase P1 on preneoplastic changes induced by cadmium and zinc chloride in the rat ventral prostate

BACKGROUND

This study was directed to evaluate the immunoexpression of markers for cell proliferation, apoptosis, nuclear androgen receptors, and Glutathione-S-Transferase P1 (GSTP1), in preneoplastic changes induced by cadmium chloride (Cd) and cadmium plus zinc chloride (Cd + Zn) in rat prostate.

METHODS

The following parameters were calculated in ventral prostate of normal rats and rats that received Cd or Cd + Zn in drinking water during 24 months: numerical densities of columnar, basal, and GSTP1 immunoreactive epithelial cells; percentages of cells immunoreactive to: PCNA, (LI(PCNA)), androgen receptors (LI(AR)), and of apoptotic cells.

RESULTS

The LI(PCNA) was significantly increased in the animals exposed to Cd + Zn, whereas the numerical densities of both columnar (N(V) columnar cells), and GSTP1 immunoreactive (N(V) GSTP1+) cells were significantly increased in the animals treated with metals in comparison with the controls. No significant differences between the two sources of dysplasias (Cd and Cd + Zn) respecting to LI(PCNA), N(V) columnar cells, and N(V) GSTP1+ were observed. The two types of dysplasias considered together showed a significant increase for the N(V) basal, N(V) columnar, and N(V) GSTP1+ cells in comparison with normal acini of treated and controls. The percentage of apoptotic nuclei did not show significant differences among the three groups studied.

CONCLUSIONS

(1) The zinc has little influence in the development of the dysplastic changes of the rat prostate mediated by cadmium. (2) The decrease of apoptosis has little influence in the development of dysplasia. (3) GSTP1 could play a role in the response to the oxidative stress in the dysplastic changes caused by cadmium.

Morphological changes and oxidative stress in rat prostate exposed to a non-carcinogenic dose of cadmium

Cadmium chloride is an environmental toxicant implicated in human prostate carcinogenesis. The mechanism of its toxicity is far from fully understood. This study evaluates the effect of exposure to an oral non-carcinogenic dose of cadmium (15 ppm in drinking water for three months) on different parameters of the ventral prostatic lobe of normal and exposed rats. We analyzed the histology by optic light microscopy, activities of antioxidant enzymes (CAT, SOD, GPx and G-6-PDH), expression of iNOS and COX-2 by Western blot, expression of MT-I, MT-II, IGF-I, IGF-BP5 and rtert by RT-PCR. Histological changes were found: the height of the cells decreased, acinar lumen were enlarged and they lost the typical invaginations. Lipoperoxidation was increased in the Cd group and the antioxidant enzymes changed their activities: SOD increased, CAT and G-6-PDH decreased and GPx did not show variations. iNOS and COX-2 did not change their expressions. MT-I and IGF-BP5 mRNA increased while MT-II, IGF-I and rtert did not show variations. Cd exposure induces important morphological changes in the prostate, which could be a consequence of lipoperoxidation and oxidative stress, which are not related to iNOS and COX-2. The histology suggests an involution state of the gland, confirmed by the expression of IGF-I, IGF-BP5 and rtert.

Cell-metal interaction studied by cytotoxic and FT-IR spectroscopic methods

The main purpose of this work is to investigate the possibility of utilizing both a classical biological method to test cytotoxicity and a physical measurement procedure as the FT-IR spectroscopy to study the interaction between cells lines and heavy metals. Jurkart, a lymphocyte cell line, was treated with cadmium chloride, cadmium oxide and the organic germanium compound named Ge-oxy-132. The utilized value of heavy metal concentration allows us to obtain significant results with both methods and with all metals. In fact by using lower values of concentration any effect is revealed after treatment with germanium. The results of the simultaneous measurements by both experimental procedures are here reported for the first time and show that, while the cytotoxic effects of the two cadmium compounds are confirmed, the organic germanium compound reveals a very different and interesting interaction with Jurkart cells. The behaviour of the Jurkart cells upon the uptake of cadmium or organic germanium is very different: while treatment with CdO and CdCl(2) determines proteins denaturation and lipids oxidation in cells until the death, these processes are not revealed after Ge-oxy-132 treatment.