Immunohistochemical localization and correlation of p53 and PCNA expression in breast carcinoma

The object of the present study is to detect the p53 tumour suppressor gene and proliferation cell nuclear antigen (PCNA) expression in breast carcinoma by immunohistochemistry and correlate them with the prognostic parameters. Total 35 cases of primary breast carcinoma were studied and classified histologically. Paraffin sections were stained by using monoclonal antibody D07 for p53 protein and PC-10 for PCNA. Out of 35 cases, 16 (45.7%) were p53 positive and 25 (71.4%) were PCNA positive. The mean PCNA labelling index (PCNA LI +/- SD) was 58.97 +/- 22.72 in tumors positive for both p53+ and PCNA+ while cases negative for p53- and positive for PCNA+ has higher PCNA LI +/- SD (59.24 +/- 18.97). The difference in the two groups was not significant. Most cases were positive for both p53+ and PCNA+ in the age group < 30 with higher mean PCNA LI +/- SD (62.20 +/- 27.13) than in the group > 30 (57.88 +/- 18.47). In the pre-menopausal group 57.1% cases were positive for p53+ with higher PCNA LI +/- SD (59.94 +/- 24.22). Maximum p53 and PCNA positivity was observed in grade III tumors (63.2% and 84.2%). The mean PCNA LI +/- SD was also highest in grade III carcinomas (66.83 +/- 13.97). No significant correlation was found between p53 and PCNA status with morphological type and tumour size except that logistic regression showed a positive correlation with tumour grade. Therefore the present study suggests that both p53 expression and PCNA are markers of poor differentiation in breast cancer.     

Prognostic factors affecting disease-free survival rate following surgical resection of primary breast cancer.

In order to identify the prognostic factors that significantly influence the disease-free survival rate after surgical resection of primary breast cancers, we determined tumour and lymph node grades, and immunohistochemical staining for estrogen and progesterone receptors (ER and PR), c-erbB-2, p53, bcl-2, bax and PCNA in 76 patients. Univariate analysis showed that increased grade of tumour and lymph nodes, negative immunostaining for ER, positive immunostaining for c-erbB-2, and a high PCNA index (> or = 30%) negatively influenced the disease-free survival rate, but PR, p53, bcl-2 and bax had no predictive value. Although p53 was not an independent prognostic factor by itself, the combination of p53, bcl-2, and bax proved to correlate with the disease-free survival, with the best prognosis noted in tumours negative for p53 and positive for both bcl-2 and bax, intermediate prognosis in tumours negative for p53 and positive for either bcl-2 or bax and worst prognosis in tumors negative for p53 as well as bcl-2 and bax. Tumour grade correlated positively with PCNA index, while positive staining for ER correlated negatively with tumour grade as well as with PCNA index, although this was statistically insignificant. Immunostaining of breast cancers for bcl-2 correlated negatively with tumour grade and PCNA index. Immunostaining for c-erbB-2 correlated positively with PCNA but not with tumour grade. Immunostaining for p53 tended to correlate positively with PCNA, but not with tumour grade. Immunostaining for PR and bax did not correlate with tumour grade and PCNA index. These results suggest that in addition to tumour size and lymph node involvement, immunostaining for ER, c-erbB-2, and a high PCNA index are important prognostic factors in human breast cancer. Wild-type p53 with preserved bcl-2 and bax gene products is also a favorable prognostic factor indicating breast cancer at an early stage of cancer progression.     

The value of immunohistochemical research on PCNA, p53 and heat shock proteins in prostate cancer management: a review

This review addresses the significance of the expression of proliferating cell nuclear antigen (PCNA), p53 and some heat shock proteins (Hsps) in prostate carcinoma (PC). In fact, PCNA and p53 are two widely discussed tools in PC diagnosis, mainly because of the controversy regarding the significance of their expression during prostate cancer development and progression. At the same time, only few studies have shown the potential role of Hsps in carcinogenesis and their overexpression in pre-neoplastic and neoplastic lesions of the prostate. We briefly describe the physiological roles of Hsps in normal cells, and the significance of their immunohistochemical detection in PC as well as in pre-cancerous lesions of the prostate. We will also discuss the possible functional interactions of these molecules in both dysplastic and neoplastic cells.     

Pathologic significance of proliferative activity and oncoprotein expression in astrocytic tumors

OBJECTIVE: To clarify the clinicopathologic significance of immunohistochemistry for proliferative activity and oncoprotein expression in astrocytic tumors. STUDY DESIGN: Ninety-seven cases of brain astrocytic tumors with histologic grading and follow-up data were investigated with immunohistochemistry and image analyzer to detect the expression of proliferating cell nuclear antigen (PCNA), silver-binding nucleolar organizer regions (AgNORs) and several oncoproteins. RESULTS: PCNA was significantly related to AgNORs, grading and prognosis of astrocytomas. The frequency of mutant p53 protein expression was higher in grade 2-4 astrocytomas than in grade 1. Epidermal growth factor (EGF) (37.1%), EGF receptor (83.5%) and p21ras (42.3%) expression levels were related to neither the grade nor prognosis of the tumors. The positive ratios of p53 antibodies were higher in grades 2-4 than in grade 1, and the intensities correlated with PCNA but not with prognosis. CONCLUSION: Aberrations of c-erbB-2, p21ras, EGF and EGF receptor might be early events in the initiation and progression of astrocytomas, whereas p53 overexpression is involved in all the stages. Immunohistochemical detection had no prognostic value. PCNA could be important to the evaluation of astrocytoma malignancy.     

Immunohistochemical expression of retinoblastoma gene product (Rb), p53 protein, MDM2, c-erbB-2, HLA-DR and proliferation indices in human urinary bladder carcinoma

Archival biopsy specimens from transitional cell bladder cancers (n=88) were analysed immunohistochemically for the expression of the retinoblastoma (Rb) gene protein, p53, mdm2, c-erbB-2, HLA-DR antigen and proliferation indices. An altered nuclear expression of Rb, p53 and mdm2 was observed in 55.2%, 33.3% and 18.2% of tumors respectively. Cytoplasmic membrane immunoreactivity (>25% tumor cells) for c-erbB-2 was detected in 14.1% of tumors and aberrant HLA-DR antigen cytoplasmic staining (>5% of tumor cells) in 22.2% of the cases. P53 overexpression was associated with higher tumor grade and stage. Aberrant HLA-DR antigen expression and PCNA were also correlated with the grade of differentiation and tumor stage. MIB1 was statistically correlated with stage. pRb scores and HLA-DR antigen expression were correlated with proliferation activity as determined by PCNA and MIB1 immunostaining. p53 protein was also strongly correlated with the proliferation index PCNA. A strong correlation between PCNA and MIB1 (p<0.0001) was also found. In addition a statistically positive correlation between p53 and HLA-DR antigen expression was observed. Our data show that, although pRb and p53 protein expressions are not associated between them, they may contribute to the growth fraction of the bladder cancer. In addition, p53 and HLA-DR antigen expression could be indicators of aggressive behavior of bladder cancer.     

p53 induces miR-199a-3p to suppress mechanistic target of rapamycin activation in cisplatin-induced acute kidney injury

How p53 participates in acute kidney injury (AKI) progress and what are the underlying mechanisms remain illusive. For this issue, it is important to probe into the role of p53 in cisplatin-induced AKI. We find that p53 was upregulated in cisplatin-induced AKI, yet, pifithrin-α inhibites the p53 expression to attenuated renal injury and cell apoptosis both in vivo cisplatin-induced AKI mice and in vitro HK-2 human renal tubular epithelial cells. To knock down p53 by siRNA significantly decreased the miRNA, miR-199a-3p, expression in HK-2 cells. Blockade of miR-199a-3p significantly reduced cisplatin-induced cell apoptosis and inhibited caspase-3 activity. Mechanistically, we identified that miR-199a-3p directly bound to mechanistic target of rapamycin (mTOR) 3′-untranslated region and overexpressed miR-199a-3p reduce the expression and phosphorylation of mTOR. Furthermore, we demonstrated that p53 inhibited mTOR activation through activating miR-199a-3p. In conclusion, our findings reveal that p53, upregulating the expression of miR-199a-3p affects the progress of cisplatin-induced AKI, which might provide a promising therapeutic target of AKI.     

PCNA and P53 expression in relation to clinicopathological features of oral papilloma

Although papilloma is the most frequent benign epithelial tumour of oral cavity, its biological potential for malignant transformation is still to be evaluated. The aim of the study was to correlate PCNA and P53 expression in 55 oral papillomas with some clinicopathological variables. The tissue samples were stained with H+E and by immunohistochemistry for PCNA and P53 protein. Staining patterns were assessed semiquantitatively and correlated with each other and grade of tumour epithelial dysplasia, tumour size, localization well patient age and sex. PCNA immunostaining was positive 43 (78%) oral papillomas. P53 immunohistochemical reaction was positive in 38 (69%) out of 55 epithelial tumours. Positive relationship between PCNA and P53 expression was observed as well as between PCNA immunostaining and grade of epithelial dysplasia. There was no statistically significant relationships between PCNA, P53 immunohistochemical positivity and papilloma size, site, patient age and sex. The results of this study suggest that immunohistochemical P53 overexpression is valuable marker of early neoplastic transformation and together with PCNA are presumed predictors for malignant transformation of oral papillomas.     

Tumor-suppressive functions of 15-Lipoxygenase-2 and RB1CC1 in prostate cancer

15-Lipoxygenase-2 (15-LOX2) is a human-specific lipid-peroxidizing enzyme most prominently expressed in epithelial cells of normal human prostate but downregulated or completely lost in > 70% of prostate cancer (PCa) cases. Transgenic expression of 15-LOX2 in the mouse prostate surprisingly causes hyperplasia. Here we first provide evidence that 15-LOX2-induced prostatic hyperplasia does not progress to PCa even in p53^+/− or p53^−/− background. More important, by generating 15-LOX2; Hi-Myc double transgenic (dTg) mice, we show that 15-LOX2 expression inhibits Myc-induced PCa development, such that in the 3-month- and 6-month-old dTg mice, there is a significant reduction in prostate intraneoplasia (PIN) and PCa prevalent in age-matched Hi-Myc prostates. The dTg prostates show increased cell senescence and expression of several senescence-associated molecules, including p27, phosphorylated Rb, and Rb1cc1. We further show that in HPCa, 15-LOX2 and c-Myc manifest reciprocal protein expression patterns. Moreover, RB1CC1 accumulates in senescing normal human prostate (NHP) cells, and in both NHP and RWPE-1 cells, the 15-LOX2 metabolic products 15(S)-HPETE and 15(S)-HETE induce RB1CC1. We finally show that unlike 15-LOX2, RB1CC1 is not lost but rather frequently overexpressed in PCa samples. RB1CC1 knockdown in PC3 cells enhances clonal growth in vitro and tumor growth in vivo. Together, our present studies provide evidence for tumor-suppressive functions for both 15-LOX2 and RB1CC1.     

Bim directly antagonizes Bcl-xl in doxorubicin-induced prostate cancer cell apoptosis independently of p53

Doxorubicin and other anthracycline compounds exert their anti-cancer effects by causing DNA damage and initiating cell cycle arrest in cancer cells, followed by apoptosis. DNA damage generally activates a p53-mediated pathway to initiate apoptosis by increasing the level of the BH3-only protein, Puma. However, p53-mediated apoptosis in response to DNA damage has not yet been validated in prostate cancers. In the current study, we used LNCaP and PC3 prostate cancer cells, representing wild type p53 and a p53-null model, to determine if DNA damage activates p53-mediated apoptosis in prostate cancers. Our results revealed that PC3 cells were 4 to 8-fold less sensitive than LNCaP cells to doxorubicin-inuced apoptosis. We proved that the differential response of LNCaP and PC3 to doxorubicin was p53-independent by introducing wild-type or dominant negative p53 into PC3 or LNCaP cells, respectively. By comparing several apoptosis-related proteins in both cell lines, we found that Bcl-xl proteins were much more abundant in PC3 cells than in LNCaP cells. We further demonstrated that Bcl-xl protects LNCaP and PC3 cells from doxorubicin-induced apoptosis by using ABT-263, an inhibitor of Bcl-xl, as a single agent or in combination with doxorubicin to treat LNCaP or PC3 cells. Bcl-xl rather than p53, likely contributes to the differential response of LNCaP and PC3 to doxorubicin in apoptosis. Finally, co-immunoprecipitation and siRNA analysis revealed that a BH3-only protein, Bim, is involved in doxorubicin-induced apoptosis by directly counteracting Bcl-xl.     

Expression of p120, Ki-67 and PCNA as proliferation biomarkers in imprint smears of prostate carcinoma and their prognostic value

The cell proliferation markers p120, Ki-67 and proliferating cell nuclear antigen (PCNA) recognize nuclear antigens. The expression of these proteins by immunostaining methods was reported to be of value in determining the prognosis of patients with malignant diseases. In this study, we evaluated the prognostic significance of the expression of nuclear antigens p120, PCNA and Ki-67 in prostate cancer and compared the results with other prognostic factors. Imprint smear samples obtained from 70 patients immediately after radical prostatectomy for prostatic carcinoma were immunostained with monoclonal antibodies against p120, Ki-67 and PCNA. The immunostaining results were correlated with Gleason score, tumour differentiation, stage and prostatic specific antigen (PSA) levels. Our findings demonstrate that p120, Ki-67 and PCNA expression in prostatic carcinoma smears, correlated significantly with the degree of Gleason score (P < 0.001). When combining p120, Ki-67 and PCNA positivity with tumour differentiation there was a significant association among these parameters (P < 0.001). Overexpression of p120, Ki-67 and PCNA, was also associated with increased PSA serum levels (>4 ng/ml) (P < 0.001). The distribution of p120, Ki-67 and PCNA expression in prostate carcinomas was not statistically significant for Ki-67 (P = 0.69) and p120 (P = 0.22) but was significant for PCNA (P < 0.001) as far as the histological stage (T2a, T2b, T2c, T3a). P120, Ki-67 and PCNA expression had significant prognostic value for disease-free survival. Our results conclude that nuclear antigens p120, Ki-67 and PCNA appear to be additional markers in the field of prognosis of prostatic carcinoma.     

Interactions between Cells with Distinct Mutations in c-MYC and Pten in Prostate Cancer

In human somatic tumorigenesis, mutations are thought to arise sporadically in individual cells surrounded by unaffected cells. This contrasts with most current transgenic models where mutations are induced synchronously in entire cell populations. Here we have modeled sporadic oncogene activation using a transgenic mouse in which c-MYC is focally activated in prostate luminal epithelial cells. Focal c-MYC expression resulted in mild pathology, but prostate-specific deletion of a single allele of the Pten tumor suppressor gene cooperated with c-MYC to induce high grade prostatic intraepithelial neoplasia (HGPIN)/cancer lesions. These lesions were in all cases associated with loss of Pten protein expression from the wild type allele. In the prostates of mice with concurrent homozygous deletion of Pten and focal c-MYC activation, double mutant (i.e. c-MYC+;Pten-null) cells were of higher grade and proliferated faster than single mutant (Pten-null) cells within the same glands. Consequently, double mutant cells outcompeted single mutant cells despite the presence of increased rates of apoptosis in the former. The p53 pathway was activated in Pten-deficient prostate cells and tissues, but c-MYC expression shifted the p53 response from senescence to apoptosis by repressing the p53 target gene p21^Cip1. We conclude that c-MYC overexpression and Pten deficiency cooperate to promote prostate tumorigenesis, but a p53-dependent apoptotic response may present a barrier to further progression. Our results highlight the utility of inducing mutations focally to model the competitive interactions between cell populations with distinct genetic alterations during tumorigenesis.     

Induction of p53-dependent activation of the human proliferating cell nuclear antigen gene in chromatin by ionizing radiation

A human fibroblast cell line with conditional p53 expression displayed a p53-dependent increase in both the protein and mRNA levels of proliferating cell nuclear antigen (PCNA) after exposure to ionizing radiation (IR). The combination of p53 induction and IR cooperated to activate a transiently expressed human PCNA promoter-reporter gene via a p53-responsive element. Chromatin immunoprecipitation assays with antibodies specific for p53 or p300/CREB-binding protein revealed specific p53-dependent enrichment of PCNA promoter sequences in immunoprecipitates of sheared chromatin prepared from irradiated cells. Maximal and specific association of acetylated histone H4 with the PCNA promoter also depended on p53 induction and exposure to IR. These data demonstrate p53 binding to a target site in the PCNA promoter, recruitment of p300/CREB-binding protein, and localized acetylation of histone H4 in an IR-dependent manner. These molecular events are likely to play a role in mediating activation of PCNA gene expression by p53 during the cellular response to DNA damage. The analyses indicate that the combination of p53 induction and IR activate the PCNA gene via mechanisms similar to that of p21/wild-type p53-activated factor but to a lesser extent. This differential regulation of PCNA and p21/wild-type p53-activated factor may establish the proper ratio of the two proteins to coordinate DNA repair with cell cycle arrest.     

p53 protein expression and proliferative activity in imprints of superficial transitional cell carcinoma of the bladder

OBJECTIVE: To investigate p53 protein expression and proliferative activity in imprints of tumor biopsies from superficial transitional cell carcinoma of the bladder in relation to the histologic grade of malignancy and recurrence status. STUDY DESIGN: The study group consisted of 70 cases of superficial transitional cell carcinoma of the bladder. In order to investigate p53 protein expression and Ki-67 expression, an immunocytochemical avidin-extravidin complex technique was performed using monoclonal antibodies p53 D0-7 and proliferating cells correspondingly. RESULTS: Thirty-seven percent of superficial transitional cell carcinoma cases showed positive expression of p53 protein. No correlation was found between p53 protein expression and grade of malignancy (P = .45). p53 Protein expression was statistically correlated with a high Ki-67 labeling index (LI) (P < .001) and recurrence status (P < .001). Forty-seven percent of cases showed a Ki-67 LI > 25%. No correlation was found between a high Ki-67 LI and grade of malignancy (P = .703). A significant difference in high Ki-67 LI between recurrent and nonrecurrent tumors of the same grade (P < .001) and between recurrent and nonrecurrent tumors was found independently of grade (P < .001). CONCLUSION: These results on cytologic material could provide useful information on the biologic behavior of superficial transitional cell carcinoma of the bladder at the time of diagnosis.     

Effect of p53 on centrosome amplification in prostate cancer cells.

Chromosomal instability (CIN) is one of the common features in prostate cancer, especially in advanced stages. Recently, the involvement of p53 in CIN through the regulation of centrosome amplification has been proposed in certain tumor types. In this study, we investigated the relationship between p53 and centrosome amplification in prostate cancer cells. Increased centrosome number and size were observed in DU145 and PC3 containing nonfunctional p53 compared to LNCap which expressed wild-type p53. Transfection of p53 into PC3 cells resulted in a decreased cell growth rate, G2/M arrest and decreased centrosome abnormalities. We provide the first evidence on a correlation between loss of p53 function and centrosome amplification in prostate cancer cells. Our results indicate that p53 may play a role in the regulation of centrosome amplification and loss of p53 may be one of the mechanisms involving CIN in prostate cancer cells.     

Zinc and p53 disrupt mitochondrial binding of HK2 by phosphorylating VDAC1

Many cell death regulators physically or functionally interact with metabolic enzymes. These interactions provide insights into mechanisms of anticancer treatments from the perspective of tumor cell metabolism and apoptosis. Recent studies have shown that zinc and p53 not only induce tumor cell apoptosis, but also regulate tumor cell metabolism. However, the underlying mechanism is complex and remains unclear, making further research imperative to provide clues for future cancer treatments. In this study, we found that hexokinase 2 (HK2), which has dual metabolic and apoptotic functions, is downstream of zinc and p53 in both prostate cancer patient tissue and prostate cancer cell lines. Notably, the mitochondrial location of HK2 is crucial for its function. We demonstrate that zinc and p53 disrupt mitochondrial binding of HK2 in prostate cancer cells by phosphorylating VDAC1, which is mediated by protein kinase B (Akt) inhibition and glycogen synthase kinase 3β (GSK3β) activation. In addition, we found that zinc combined with p53 significantly inhibited tumor growth in a prostate cancer cell xenograft model. Therefore, interference of the mitochondrial localization of HK2 by zinc and p53 may provide a new treatment approach for cancer.     

Prostate-specific expression of p53(R172L) differentially regulates p21, Bax, and mdm2 to inhibit prostate cancer progression and prolong survival

Loss of heterozygosity or mutation at the p53 tumor suppressor gene locus is frequently associated with advanced human prostate cancer. Hence, replacement p53 gene therapy may prove to be efficacious for this disease. While many mutations result in p53 molecules with oncogenic properties, other variants may possess wild-type properties with increased tumor suppressor activity. We have chosen to investigate the activity of a naturally occurring variant p53 molecule, p53(R172L), carrying an arginine-to-leucine mutation at codon 172. We demonstrate that p53(R172L) can differentially activate expression of genes involved in cell cycle control and apoptosis in vitro. Transgenic mice expressing a subphysiological level of a p53(R172L) minigene (PB-p53(R172L)) in the prostate epithelium were generated and bred to the transgenic adenocarcinoma mouse prostate (TRAMP) model of prostate cancer. While PB-p53(R172L) transgenic mice developed normally with no detectable prostate gland phenotype, we observed a significant increase in the apoptotic index in the prostate glands of TRAMP x PB-p53(R172L) F1 mice. We noted an increase in the expression of Bax in the bigenic mice concomitant with the reduced incidence and rate of tumor growth and increased survival. While low-level expression of the p53(R172L) variant had no obvious influence on normal prostate tissue, it was able to significantly inhibit prostate cancer progression in the context of a genetically predisposed model system. This suggests that additional tumor-related events specifically influence the ability of the variant p53(R172L) molecule to inhibit tumor growth. These studies support gene therapy strategies employing specific p53 variants.