p21/WAF1/CIP1 expression in normal mucosa and in adenomas and adenocarcinomas of the colon: its relationship with differentiation

A case of adenocarcinoma of the small intestine in a Japanese patient with Crohn disease: a report with immunohistochemical and oncogenic analyses

We report a rare case of Crohn disease accompanied by a small-bowel carcinoma that developed in a 54-year-old Japanese man. The ulcerating tumor, which histologically proved to be a poorly differentiated adenocarcinoma and dysplasia surrounding the carcinoma, was located in the diseased ileum. The Ki-67 immunoreactive epithelial cells were increased in regenerative mucosa as compared with values for normal mucosa. The Ki-67- and p53-positive cells were increased in dysplasia and carcinoma as compared with values for regenerative or normal mucosa. In contrast, the p21(WAF1/CIP1) immunoreactive cells were decreased in this order. Intense DCC (deleted in colorectal cancer) expression was constantly shown among normal, regenerative, dysplastic and cancerous tissues. No bcl-2 expression and c-Ki-ras mutations were apparent. In conclusion, enhanced epithelial cell proliferation, p53 overexpression, and decrease of p21(WAF1/CIP1) expression may predispose the small-bowel mucosa to dysplasia and carcinoma development in Crohn disease.

p22/WAF1 expression in human colorectal carcinoma: association with p53, transcription factor AP-2 and prognosis

p21/WAF1 expression was studied in a series of 162 colorectal carcinoma patients and its relation to p53- and activator protein (AP)-2 expressions and to stage as well as survival was assessed. p21 expression was moderate or intense in 33% of the tumours, and 53% of the tumours had moderate or strong p53 staining intensity. Eighty-nine percent of the tumours showed a weak cytoplasmic AP-2 signal. As expected, p21 and p53 stainings were inversely related to each other (P < 0.001). There was a significant positive association between p21 and AP-2 expression levels (P= 0.01). p21 intensity and percentage were higher in Dukes' A and B stages (P< 0.001). The cancer-related survival and recurrence-free survival (RFS) rates were significantly lower among patients with a low signal for p21 (P< 0.001) and low p21 percentage in tumour epithelium (P < 0.001). High p53 staining intensity in tumour epithelium predicted poor survival (P = 0.01) and RFS (P = 0.003). In the multivariate analysis, p21 percentage distribution independently predicted cancer-related survival in all cases, and p21 expression intensity in T1-4/N0-3/M0 and T1-3/N0/M0 cases. p21 percentage distribution was an independent predictor of RFS in all and T1-3/N0/M0 cases. AP-2 staining did not reach any prognostic significance. These results suggest that the immunohistochemical detection of cyclin-dependent kinase inhibitor p21 could be used to predict more precisely the outcome of colorectal cancer patients.

Protein expression and genetic alterations of p53 and ras in intrahepatic cholangiocarcinoma

AIMS

The significance of molecular and genetic alterations of p53 and ras in the development and progression as well as the histological differentiation of intrahepatic cholangiocarcinoma (ICC) was evaluated.

METHODS AND RESULTS

We examined immunohistochemically ras p21 protein and p53-related products (p53 protein, WAF-1 and mdm-2) in 43 cases of ICC. In addition, point mutations of ras and p53 were examined genetically in selected ICC cases by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and direct sequence analysis. Point mutation of K-ras gene codon 12 was detected in three of 14 cases and one of 15 cases by PCR-RFLP and direct sequence analysis, respectively. Immunoreactivity of ras p21 protein was not detected. Point mutation of p53 was detected in three of 15 cases. p53 protein was immunohistochemically detectable in 33 of 43 cases. Immunoreactivity of p53 was more frequent in well-differentiated and less frequent in poorly differentiated cases. Immunoreactivity of WAF-1 and mdm-2 was seen in 16 and eight of 43 cases, respectively. Both proteins were frequently detected in the cases positive for p53 protein.

CONCLUSION

These results suggest that dysregulation of ras is involved in at least 20% of ICC and expression of p53 protein is more significantly involved in ICC, particularly in the well and moderately differentiated cases. While some cases of p53 expression may be explainable by point mutation of p53, there may be some epigenetic phenomena that stabilize p53 protein in ICC. That is, wild type p53 may be stabilized and then detectable by forming complexes with other molecules of p53 downstream effector genes, such as WAF-1 and mdm-2.

p53 and p21/Waf1 protein expression and K-ras codon 12 mutation in carcinoma of the papilla of Vater

OBJECTIVE

There have been few studies on the molecular biological characteristics of carcinoma of the papilla of Vater. In this study, p53 and p21/Waf1 expression and K-ras codon 12 mutation in carcinoma of the papilla of Vater were investigated.

METHODS

Thirty-seven cases of carcinoma of the papilla of Vater were studied. Macroscopically, the carcinoma was ulcerative in 15 cases and nonulcerative in 22 cases. Histologically, nine were intestinal type, 27 were pancreaticobiliary type, and one was undifferentiated. Formalin-fixed, paraffin-embedded sections were immunohistochemically stained for p53 and p21. K-ras codon 12 mutation was detected with the two-step polymerase chain reaction-restriction fragment length polymorphism method, followed by direct sequencing.

RESULTS

p53 overexpression was found in 17 of 37 cases (46%) and was more frequent in the ulcerative type than in the nonulcerative type (67% vs 32%, p < 0.05). p21/Waf1 protein expression was found in 15 of 37 cases (41%), and was not correlated with that of p53. K-ras codon 12 mutation was found in 14 of 37 cases (38%), and was more frequently detected in the intestinal type than in the pancreaticobiliary type (66% vs 30%, p < 0.05). On direct sequencing, the mutations were mainly GGT to GAT (9/14) and GGT to GTT (4/14). The type of mutation did not correlate with the histological type.

CONCLUSIONS

In carcinoma of the papilla of Vater, p53 overexpression may play a role in tumor ulceration. p21/Waf1 expression is induced via a p53-independent pathway. Carcinomas of the intestinal and pancreaticobiliary types may develop via different mechanisms, and K-ras mutation is mainly associated with the intestinal type.

Molecular heterogeneity in medulloblastoma with implications for differing tumor biology

Medulloblastomas and related primitive neuroectodermal tumors are the second most common malignant tumors of childhood. In spite of improvements in cancer therapy, these tumors are still associated with significant morbidity and mortality. Although these tumors share similar histologic features, recent molecular studies suggest that they could represent a genetically mixed group of tumors. The genetic events that might play a role in the biology of these tumors also could allow a molecular subtyping of medulloblastomas. Such molecular subtyping of medulloblastomas could allow for the use of newer therapeutic techniques, such as gene therapy, for selective targeting of critical genetic events in subsets of medulloblastomas. It is becoming increasingly clear that in medulloblastomas, the morphologic similarity of "small blue" cells does not imply similar or shared molecular characteristics, with implications for differing tumor biology.

Downregulation of p21/WAF1 is related to advanced and dedifferentiated laryngeal squamous cell carcinoma

AIM

To analyse p21/WAF1 expression and its relation to p53, apoptosis, cell proliferation, clinicopathological characteristics, and patient survival in human laryngeal squamous cell carcinoma.

METHODS

Primary tumours for analyses were obtained from 172 patients with complete follow up data. All patients were treated between 1975 and 1995. Immunohistochemistry was used to evaluate the expression of p21/WAF1, bcl-2, and p53 proteins. The proliferative activity was determined using Ki67 and PCNA antibodies as well as volume corrected mitotic count (M/V index). Volume corrected apoptotic count (A/V index) was determined using an enzymatic in situ cell death detection kit based on the TUNEL method.

RESULTS

High p21 expression was significantly related to high p53 and normal bcl-2 expressions as well as low mitotic count. No association was noticed between p21 expression and apoptotic rate. A significant inverse correlation between p21 expression and advanced stage and poor differentiation was observed, but p21 expression showed no correlation with survival.

CONCLUSIONS

The expression of p21 was associated with tumour stage, histopathological grade, node status, and mitotic count, which may indicate a role for p21 in the progression of laryngeal squamous cell carcinoma.

p21/WAF1 expression as related to p53, cell proliferation and prognosis in epithelial ovarian cancer

The role and prognostic value of the tumour suppressor p21/WAF1 expression in epithelial ovarian cancer has not yet been defined. Therefore, the expression of p21/WAF1 was assessed immunohistochemically (IHC) in 316 epithelial ovarian malignancies in relation to p53, cell proliferation and patient survival. p21/WAF1 expression was inversely correlated with p53 and cell proliferation. Low p21/WAF1 expression was significantly associated with high grade of the tumour (P = 0.0005), advanced FIGO stage (P = 0.001) and primary residual tumour (P = 0.0001). Low p21/WAF1 expression was a marker of poor overall survival (P = 0.012). Similarly, p53-positivity and high cell proliferative activity were significant predictors of poor survival in univariate analyses. Moreover, the patients with p21-/p53+ tumours had a poorer overall (P < 0.00005) and recurrence-free (P = 0.0005) survival in univariate analyses, and the p21/p53 expression independently predicted tumour recurrence in Cox's multivariate analysis. Our results suggest that p21/WAF1 expression is mostly p53-dependent in epithelial ovarian cancer. High p21/WAF1 expression seems to function as a negative cell cycle regulator and as a marker of favourable disease outcome in epithelial ovarian cancer. In addition, the patients with their tumour expressing no or low p21/WAF1 protein but positive for p53 had a notably higher risk of recurrent disease, implicating that these patients might be more prone to treatment failures.

Prognostic value and expression of p21(waf1/cip1) protein in prostate cancer

BACKGROUND

p21(waf1/cip1) protein is a cyclin-dependent kinase inhibitor able to arrest the cell cycle at the G1 phase by inhibiting DNA replication. The expression of p21(waf1/cip1) and its prognostic value in prostate cancer are largely unexplored.

METHODS

We used immunohistochemistry to analyze the expression of p21(waf1/cip1) in 213 prostate cancer cases, and the results were related to other known prognostic factors and patient survival during a long-term follow-up.

RESULTS

The expression of p21 (waf1/cip1) protein was significantly associated with high Gleason score (P = 0.001), DNA aneuploidy (P = 0.013), high S-phase fraction (P = 0.019), and expression of Ki-67 (P = 0.021) and bcl-2 (P = 0.001) as well as cyclin A (P = 0.035) and D proteins (P<0.001). In univariate survival analysis the signal of p21(waf1/cip1) was significantly related to unfavorable prognosis (P = 0.010) both in the entire cohort and in local tumors (P = 0.034). In multivariate analysis, M-category, clinical T-category, Gleason score, and patient age were independent prognostic factors. In local tumors the expression of p21(waf1/cip1) together with clinical T-category and S-phase fraction were significant independent predictors of cancer related survival.

CONCLUSIONS

The results suggest that the expression of p21(waf1/cip1) protein is associated both with cell proliferation and patient survival in prostate cancer.

Expression of p53, p21/waf, bcl-2, bax, Rb and Ki67 proteins in colorectal adenocarcinomas

This study investigated the combined immunoexpression of p53, p21, bcl-2, bax, Rb and Ki67 proteins in colorectal adenocarcinomas and correlated expression patterns with tumour stage and grade. Paraffin sections from 98 cases of colorectal adenocarcinomas were stained by immunohistochemistry for p53, p21, bcl-2, bax, Rb and MIB-1 (Ki67) proteins. In addition, 12 cases of colorectal adenomas and normal colorectal mucosa were studied in parallel. P53, p21, bcl-2, bax, Rb and Ki67 proteins were detected in at least 5% of tumour cells in 63/98, 72/98, 52/98, 96/98 and 98/98 adenocarcinomas, respectively. Comparative study of the normal-adenoma-carcinoma tissues revealed abrogation of the normal immunotopography in adenomas and adenocarcinomas, and considerable modifications, increase or reduction, of the expression of p53, p21, bcl-2, bax, Rb and Ki67 proteins in adenocarcinomas when compared with normal mucosa and adenomas. Statistically significant correlations were found between low bax expression and Dukes C stage of carcinomas, Ki67 expression and carcinoma grade, and Ki67 and Rb expression. P53, p21, bcl-2 and Rb immunoexpression did not correlate with tumour stage or grade. Our findings show that low bax immunoexpression is frequently related to colorectal adenocarcinomas with lymph node metastases suggesting that low levels of bax expression play a role in late stage colorectal cancer. The correlation between Ki67 and Rb expression, in view of previous data that the hyperphosphorylated inactive Rb protein is frequently increased in colorectal adenocarcinomas, suggests that Rb protein is somewhat ineffective in inhibiting the cell-cycle progression in these malignancies. Furthermore, our findings provide immunohistochemical evidence that the abrogation of the normal immunotopography and the modifications of the expression of p53, p21, bcl-2, bax, Rb and Ki67 proteins reflect important events in colorectal oncogenesis.

Concerted overexpression of the genes encoding p21 and cyclin D1 is associated with growth inhibition and differentiation in various carcinomas

AIMS

To investigate the expression of the genes encoding cyclin D1 and p21 in proliferative and non-proliferative cells, as demonstrated by the Ki67 antibody, and to correlate these findings with differentiation.

METHODS

Immunohistochemistry and immunofluorescence double staining were performed on three breast cancers, two squamous cell cancers of the head and neck, and one ovarium cystadenocarcinoma. In addition, the in vitro effect of cyclin D1 on p21 gene expression in MCF7 breast cancer cells was evaluated.

RESULTS

Immunofluorescence double staining showed a differentiation related gradient in the detection of the Ki67 antigen, cyclin D1, and p21 in squamous cell cancers of the head and neck: Ki67 was detected in the basal layers of the tumour and the cyclin D1 and p21 genes were coexpressed in the higher, more differentiated layers of the tumour. The breast and ovarian cancers often had cells that coexpressed the p21 and cyclin D1 genes, whereas coexpression of cyclin D1 and Ki67 did not occur. Western blot analysis of the MCF7 breast cancer cells showed an upregulation of p21 production when cyclin D1 gene expression was induced.

CONCLUSION

Overexpression of the cyclin D1 gene seems to lead to growth arrest in a variety of human cancers, possibly through the induction of p21 by cyclin D1. In squamous cell cancer, concerted overexpression of the genes encoding cyclin D1 and p21 might also induce differentiation.

Prognostic role of p27Kip1 and apoptosis in human breast cancer

Human breast carcinoma is biologically heterogeneous, and its clinical course may vary from an indolent slowly progressive one to a course associated with rapid progression and metastatic spread. It is important to establish prognostic factors which will define subgroups of patients with low vs high risk of recurrence so as to better define the need for additional therapy. Additional characterization of the molecular make-up of breast cancer phenotypes should provide important insights into the biology of breast cancer. In the present study, we investigated apoptosis, expression of p27Kip1 and p53 retrospectively in 181 human breast cancer specimens. In addition, their relevance to the biological behaviour of breast cancer was examined. Our studies found a significant association among high histological grade, high p53, low apoptosis and low p27. Our results also demonstrated that, in human breast cancer, low levels of p27 and apoptotic index (AI) strongly correlated with the presence of lymph node metastasis and decreased patient survival. In node-negative patients, however, p27 also had prognostic value for relapse-free and overall survival in multivariate analysis. Furthermore p27 and AI had predictive value for the benefits of chemotherapy. These latter observations should prompt prospective randomized studies designed to investigate the predictive role of p27 and AI in determining who should receive chemotherapy in node-negative patients.

p21WAF1/CIP1 expression in colorectal carcinoma correlates with advanced disease stage and p53 mutations

Defects in the mechanisms controlling the cell cycle are crucial in cell transformation and/or tumour progression. p21WAF1/CIP1 is an inhibitor of cyclin-dependent kinases, induced by p53-dependent and p53-independent pathways, which can block progression through the cell cycle. p21WAF1/CIP1 expression has been investigated immunohistochemically in a series of 191 patients with colorectal cancer of known p53 status. The purpose of the study was two-fold: to assess the relationship between p21WAF1/CIP1 immunoreactivity and p53 alterations, and to evaluate the prognostic significance of p21WAF1/CIP1 expression. In 96 carcinomas (51 per cent), p21WAF1/CIP1 was expressed in over 10 per cent of tumour cells, whereas in 26, p21WAF1/CIP1 was detected in under 10 per cent of neoplastic cells; 69 tumours lacked p21WAF1/CIP1 expression. Immunoreactivity was more frequent in tumours of the right colon (p < 0.003) and was inversely correlated with tumour stage (p < 0.03), p53 gene mutations (p < 0.0007), p53 protein accumulation (p < 0.019), and Bcl-2 expression (p < 0.0005). In univariate analysis, down-regulation of p21WAF1/CIP1 expression was associated with poor overall (p = 0.0022) and disease-free survival (p = 0.0009). Multivariate analysis, however, did not confirm any independent prognostic significance of p21WAF1/CIP1 expression. The results indicate that p21WAF1/CIP1 is associated with abnormal accumulation of p53 protein and the occurrence of p53 gene mutations in colorectal cancer and that lack of p21WAF1/CIP1 expression is correlated with reduced patient survival in univariate analysis. These data underline the crucial pathogenetic role of the p53-p21WAF1/CIP1 pathway in carcinomas of the large bowel.

p21(WAF1/CIP1) expression in stage I cutaneous malignant melanoma: its relationship with p53, cell proliferation and survival

The expression of p21, p53 and proliferating cell nuclear antigen (PCNA) was analysed by immunohistochemistry in a consecutive series of 369 clinical stage I cutaneous malignant melanoma patients. Correlation of the detected expression levels with each other, with clinicopathological data and with melanoma survival were statistically evaluated. p21 expression was significantly associated with p53 and PCNA expression levels. In addition, high levels of p53 and PCNA were significantly interrelated. Tumour thickness, recurrent disease, high TNM category and older (> or = 55 years) age at diagnosis were inversely associated with p21 expression. Gender, bleeding, tumour thickness, Clark's level of invasion, TNM category and p53 index were all important predictors of both recurrence-free and overall survival of melanoma. In Cox's multivariate analysis including 164 patients with a complete set of data, only high tumour thickness and bleeding predicted poor recurrence-free survival (P = 0.0042 and 0.0087 respectively) or overall survival (P = 0.0147 and 0.0033 respectively). Even though elevated p21 expression may be associated with more favourable prognosis in clinical stage I cutaneous melanoma, our results suggest that cell cycle regulatory effects of p21 can be overcome by some other and stronger, partly yet unknown, mechanisms.

Comparative effects of overexpression of p27Kip1 and p21Cip1/Waf1 on growth and differentiation in human colon carcinoma cells

Recent studies have shown that decreased expression of p27Kip1 is associated with high grade tumors and an unfavorable prognosis in several types of human cancer. To clarify the role of p27Kip1 in colon cancer, we have overexpressed this protein in the HT29 colon cancer cell line. The derivatives displayed an increase in the p27Kip1 protein in cyclin E/CDK2 immunoprecipitates and a decrease in cyclin E-associated kinase activity when compared to vector control clones, providing evidence that the overexpressed protein was functional. Clones with a high level of p27Kip1 displayed partial growth inhibition in monolayer culture and a decrease in plating efficiency, even though they expressed increased levels of the cyclin D1 protein. Using alkaline phosphatase expression as a marker, we found that the p27Kip1 overexpressor clones displayed a 2-3-fold increase in sensitivity to induction of differentiation by 2 mM sodium butyrate. In contrast to these results, derivatives of HT29 cells that stably overexpressed p21Cip1/Waf1 displayed decreased sensitivity to the induction of differentiation. These findings may explain why decreased levels of p27Kip1 in certain human cancers is associated with high grade (poorly differentiated) tumors, and suggest that strategies that increase the level of p27Kip1 may be useful in cancer therapy.

Cell cycle regulators and their abnormalities in breast cancer

One of the main properties of cancer cells is their increased and deregulated proliferative activity. It is now well known that abnormalities in many positive and negative modulators of the cell cycle are frequent in many cancer types, including breast carcinomas. Abnormalities such as defective function of the retinoblastoma gene and cyclin-dependent kinase inhibitors (for example, p16, p21, and p27), as well as upregulation of cyclins, are often seen in breast tumours. These abnormalities are sometimes coincidental, and newly described interplays between them suggest the existence of a complex regulatory web in the cell cycle.

Expression of p21WAF1/CIP1 in soft tissue sarcomas: a comparative immunohistochemical study with p53 and Ki-67

The p53 gene controls the cell cycle by transactivating p21WAF1/CIP1, a cyclin dependent kinase (cdk) inhibitor. By inhibiting cdks, p21WAF1/CIP1 regulates the cell cycle by blocking the G1 to S phase transition. In this study, we analyzed the immunohistochemical expression of p21WAF1/CIP1 in 66 soft tissue sarcomas and its relationship to p53 and the cell cycle proliferation antigen Ki-67. Expression of p21WAF1/CIP1, was detected in 76% of the tumors and p53 in 26%. All malignant schwannomas, synovial sarcomas, leiomyosarcomas and gastrointestinal stromal tumors expressed p21WAF1/CIP1. The majority of angiosarcomas, dermatofibrosarcomas, and fibrosarcomas showed low expression or were negative for p21WAF1/CIP1. Ewing's sarcomas, liposarcomas, and malignant fibrous histiocytomas were heterogeneous in their expression of p21WAF1/CIP1. Combining p53 and p21WAF1/CIP1 staining, the following four patterns were observed: 23% of the tumors showed the p53+/p21+ pattern; 53% showed the p53-/p21+ pattern; 3% showed the p53+/p21- pattern and 21% were negative for both p53 and p21WAF1/CIP1. There was no correlation between Ki-67 and p21WAF1/CIP1 or p53 staining. Our results show that soft tissue sarcomas, independent of their histologic subtype, frequently express p21WAF1/CIP1 which is probably important in their tumorigenesis. Additionally, p21WAF1/CIP1 may play a role in determining the efficacy of various cell cycle-directed therapies in soft tissue sarcomas.

The cell cycle: a review

The cell cycle is a complex process that involves numerous regulatory proteins that direct the cell through a specific sequence of events culminating in mitosis and the production of two daughter cells. Central to this process are the cyclin-dependent kinases (cdks), which complex with the cyclin proteins. These proteins regulate the cell's progression through the stages of the cell cycle and are in turn regulated by numerous proteins, including p53, p21, p16, and cdc25. Downstream targets of cyclin-cdk complexes include pRb and E2F. The cell cycle can be altered to the advantage of many viral agents, most notably polyomaviruses, papillomaviruses, and adenoviruses. The cell cycle often is dysregulated in neoplasia due to alterations either in oncogenes that indirectly affect the cell cycle or in tumor suppressor genes or oncogenes that directly impact cell cycle regulation, such as pRb, p53, p16, cyclin D1, or mdm-2. The cell cycle has become an intense subject of research in recent years. This research has led to the development of techniques useful for the determination of the effects of drugs and toxins on the cell cycle. Any drug or toxin with DNA damaging ability would be expected to alter cell cycle progression, and therefore, the cell cycle should be considered in the design of studies using such chemicals. With the appropriate techniques, cell cycle alterations may also be detected in tissue sections. Because of the ubiquitous nature of the cell cycle, it deserves consideration in the design and interpretation of studies in a wide variety of disciplines.

Expression of p21 (Waf1/Cip1) in head and neck cancer in relation to proliferation, differentiation, p53 status and cyclin D1 expression

p21(Waf1/Cipl) is a critical downstream effector in the p53-dependent pathway of growth control and causes growth arrest through inhibition of cyclin-dependent kinases. In this study 67% of 43 head and neck squamous cell carcinoma (HNSCC) and 60% of 15 tumour-adjacent oral dysplasias overexpressed p21 by immunohistochemical staining. Overexpression of p21 in HNSCC was independent of the presence of functional p53, as assessed by analysis of mutations and loss of heterozygosity and by immunohistochemisty. Rather, the expression pattern of p21 was associated with differentiation. Furthermore, in most tumours, the p21 positive cells did not incorporate bromodeoxyuridine (BrdU), which indicates inhibition of proliferation by p21 in these cells. In some tumours, p21 was also expressed in proliferating cells. In these latter tumour cells, cyclin D1 was frequently expressed as well. Therefore, we suggest that expression of cyclin D1 might overcome the inhibitory effect of p21 in these cells.

Expression of cyclin dependent kinase inhibitor p21waf1/cip1 in premalignant and malignant oral lesions: relationship with p53 status

p21waf1/cip1 protein, an inhibitor of cyclin dependent kinases, is a critical downstream target in the p53-specific pathway of growth control, and can also be induced by p53 independent pathways in relation to terminal differentiation. p21waf1 is also a putative tumour suppressor. Hence, we sought to determine whether this protein is abnormally expressed during betel- and tobacco-related oral oncogenesis. The aim was to determine whether a correlation exists between the expression profile of p21 and clinicopathological parameters of the patients, as well as with their p53 status. Immunohistochemical analysis showed that the expression of p21 protein in premalignant lesions was consistently elevated in the superficial, differentiated cells of the epithelium, while overexpression of the p53 tumour suppressor gene was observed in the basal proliferating layers of the epithelium. Our study demonstrated that p21 overexpression is associated with differentiation in proliferating dysplasias and squamous cell carcinomas (SCCs). The expression of p21 and p53 proteins was observed in 11/25 premalignant lesions. In 7 of these 11 cases, a heterogenous pattern of expression of p21 and p53 was observed. Four of these 11 premalignant and 30/51 malignant lesions showed concordant expression of both p21 and p53 proteins. The discordant p21 +/p53- phenotype was observed in 4/25 premalignant lesions and 5/51 oral SCCs. The p21-/p53+ phenotype was observed in 5/25 premalignant lesions and 7/51 oral SCCs. These results suggest that induction of p21 occurs by both p53 dependent and independent mechanisms during oral tumorigenesis.

Expression patterns of cyclin D1 and related proteins regulating G1-S phase transition in uveal melanoma and retinoblastoma

BACKGROUND/AIMS

A checkpoint mechanism in late G1, whose regulation via loss of retinoblastoma protein (pRB) or p16, or overexpression of cyclin D1 or cyclin dependent kinase 4 (CDK4), has been proposed to constitute a common pathway to malignancy. The aims of this study were (a) to compare markers of cell cycle G1-S phase transition in an intraocular tumour with known pRB deficiency (retinoblastoma) and compare it with one with an apparently functional pRB (uveal melanoma); (b) to determine if one of these markers may have a role in the pathogenesis of uveal melanoma; and (c) to determine if there is a difference in cell cycle marker expression following treatment of uveal melanoma and retinoblastoma.

METHODS

90 eyes were enucleated from 89 patients for retinoblastoma (n = 24) or for choroidal or ciliary body melanoma (n = 66). Conventional paraffin sections were assessed for cell type and degree of differentiation. Additional slides were investigated applying standard immunohistochemical methods with antibodies specific for cyclin D1 protein, pRB, p53, p21, p16, BCL-2, and MIB-1.

RESULTS

Cyclin D1 protein and pRB were negative in retinoblastoma using the applied antibodies. In contrast, cyclin D1 protein expression was observed in 65% of uveal melanomas; a positive correlation between cyclin D1 cell positivity and tumour cell type, location, growth fraction, as well as with pRB positivity was observed. p53, p21, and p16 could be demonstrated in both tumours. An inverse relation between p53 and p21 expression was demonstrated in most choroidal melanomas and in some retinoblastomas. Apart from a decrease in the growth fractions of the tumours as determined by MIB-1, a significant difference in the expression of G1-S phase transition markers in vital areas of uveal melanoma and retinoblastoma following treatment with radiotherapy and/or chemotherapy was not observed.

CONCLUSION

Retinoblastomas and uveal melanomas, two tumours of differing pRB status, differ also in their immunohistochemical pattern for markers of the G1-S phase transition of the cell cycle. The results of the present study support the concept of (a) an autoregulatory loop between pRB and cyclin D1 in tumours with a functional pRB and the disruption of this loop in the presence of pRB mutation, as well as (b) a checkpoint mechanism in late G1, whose regulation via loss of p16 or pRB, or overexpression of cyclin D1 constitutes a common pathway to malignancy. Further, the results raise the possibility of cyclin D1 overexpression having a role in the pathogenesis of uveal melanoma.

Intestinal cell cycle regulation

The intestinal epithelium is maintained by a balance between proliferation, differentiation and death that occurs as cells migrate up the crypt-villus axis. Cell cycle regulators such as cyclins, cyclin-dependent kinases (Cdks) and Cdk inhibitory proteins are expressed in a distinct pattern along the crypt-villus structure, suggesting their role in controlling intestinal cells. This is supported by observations that these cell cycle proteins are regulated by growth factors, nutrients and cell-cell contact in cultured intestinal epithelial cells. One of the key regulators of intestinal cell proliferation and differentiation is transforming growth factor-beta, which is expressed in the gut epithelium.

p21WAF1/Cip1 is associated with cyclin D1CCND1 expression and tubular differentiation but is independent of p53 overexpression in human breast carcinoma

p21WAF1/Cip1 is an inhibitor of cdk/cyclin complexes, and thus regulates the cell cycle. p21 is also related to cell differentiation and is regulated by wild-type p53, although p53-independent regulatory pathways have been proposed. In order to analyse p21 expression as well as its relationship with p53 in human breast cancer, an immunohistochemical analysis was undertaken of 77 breast carcinomas, 16 of them with an in situ component; 30 adjacent normal tissue samples; and five non-neoplastic specimens. Forty-four infiltrating carcinomas (57 per cent) were p21-positive. Expression of p21 was also observed in pre-invasive lesions, whereas normal ducts were negative or focally and weakly positive. p21 expression was associated with high histological grade (II + III) (P = 0.017) and poor tubule formation (P = 0.002), and was significantly less frequent in lobular carcinomas (P = 0.0001). p21 positivity also correlated with increased proliferation, but this seemed to be dependent on the histological grade. Twenty carcinomas (26 per cent) showed p53 overexpression, but this was not associated with p21 negativity, suggesting the existence of p53-independent mechanisms for p21 regulation in vivo. Cyclin D1CCND1 expression was analysed in the same series and an association between p21 and cyclin D1 expression was found, since 23 of 26 cyclin D1-positive carcinomas were p21-positive (P < 0.001 ...). In conclusion, p21 is frequently overexpressed in breast carcinomas and this occurs in the early stages of neoplastic progression. This overexpression seems to be independent of p53 status and might be involved in cyclin D1 modulation.

p21WAF1/CIP1 expression in gestational trophoblastic disease: correlation with clinicopathological parameters, and Ki67 and p53 gene expression

BACKGROUND

The p21WAF1/CIP1 gene mediates growth arrest by inhibiting G1 cyclin dependent kinases and has been considered as a downstream effector of the tumour suppressor gene p53.

AIM

To analyse the role of p21WAF1/CIP1 in gestational trophoblastic disease.

METHODS

The immunohistochemical expression of p21WAF1/CIP1 gene was measured in 33 placentas, 28 partial hydatidiform moles, 54 complete hydatidiform moles, and 13 choriocarcinomas in paraffin wax embedded tissue. The results were correlated with p53 (DO7) and Ki67 (MIB1) immunoreactivity as well as clinical progress.

RESULTS

p21WAF1/CIP1 immunoreactivity was found predominantly in the nuclei of the syncytiotrophoblasts. p21WAF1/CIP1 protein expression correlated with gestational age in normal placentas (p = 0.0001) but not in hydatidiform moles (p = 0.89). Complete hydatidiform moles and choriocarcinomas had a significantly higher p21WAF1/CIP1 expression compared with normal placentas and partial hydatidiform moles (p < 0.001); there was no difference between placentas and partial hydatidiform moles. No correlation between p21WAF1/CIP1 expression and either the proliferation (Ki67) index (p = 0.34) or p53 protein accumulation (p = 0.68) was demonstrated. There was no significant difference (p > 0.05) in p21WAF1/CIP1 expression between the 17 patients who developed persistent gestational trophoblastic disease and those who did not.

CONCLUSIONS

This study suggests that p21WAF1/CIP1 expression in trophoblastic disease may be induced by a p53 independent pathway. The proliferative activity of gestational trophoblastic diseases might not be determined solely by the control of the cell cycle operated by p21WAF1/CIP1. p21WAF1/CIP1 expression is not an accurate prognostic indicator of gestational trophoblastic disease.

p21/waf1/cip1 and mdm-2 expression in breast carcinoma patients as related to prognosis

p21/waf1/cip1 and mdm-2 are downstream effectors of p53. p21 plays a major role in negatively regulating cell-cycle progression, while mdm-2 inhibits p53 effects, and its role has been implicated in oncogenesis. In this study, we investigated the expression profiles of p21, mdm-2 and p53 in human breast-carcinoma tissues. The aim was to determine whether a correlation exists between the expression profiles of these markers and tumor differentiation, ER status and prognosis. We studied tumor specimens obtained from 106 patients and found a highly significant association among low histology grade, p53 over-expression, high mdm-2 expression and lack of p21 expression. Our studies also demonstrate that, in human breast cancer, low levels of p21 and higher mdm-2 levels directly correlate with the onset of lymph-node metastases and shortened patient survival. Furthermore, the expression profiles of p21, mdm-2 and p53 were independently correlated with patient survival.

p21WAF1/Cip1 expression is associated with cell differentiation but not with p53 mutations in squamous cell carcinomas of the larynx

p21WAF1/Cip1 is a recently identified gene involved in cell cycle regulation through cyclin-CDK-complex inhibition. The expression of this gene in several cell lines seems to be induced by wild-type, but not mutant, p53. p21WAF1/Cip1 expression has been studied at both mRNA and protein levels in a series of 49 normal mucosae and squamous cell carcinomas of the larynx. A significant association was found between mRNA and protein expression in tumours (P < 0.0001). p21WAF1/Cip1 expression was strongly associated with squamous cell differentiation of carcinomas, because six of seven (86 per cent) undifferentiated carcinomas (grade 4) showed very low levels of p21WAF1/Cip1 expression, whereas 41 out of 42 (98 per cent) carcinomas with squamous cell differentiation (grades 1-3) had normal or high levels of p21WAF1/Cip1 expression (P < 0.0001). In addition, p21WAF1/Cip1 expression was topologically related to the squamous differentiation of tumour cells with a distribution similar to that seen in normal squamous epithelium. No correlation was found between p21WAF1/Cip1 expression and the global S-phase of the carcinomas. p53 mutations (exons 5-9) were found in ten carcinomas with p21WAF1/Cip1 expression, but no p53 mutations were detected in three p21WAF1/Cip1-negative tumours. In conclusion, p21WAF1/Cip1 expression is frequently upregulated in squamous cell carcinomas of the larynx and is associated with tumour cell differentiation. p21WAF1/Cip1 expression in these tumours is independent of p53 gene mutations.

Biomarkers for predicting response to regional chemo-immunotherapy in liver metastases from colorectal carcinoma

Differences in therapeutic outcomes after regional chemotherapy or chemo-immunotherapy in liver metastases from colorectal carcinoma cannot be explained only by variations in the regimens of treatment. This study was undertaken to assess the potential of several tumor-associated markers of biological behavior (biomarkers) to predict therapeutic response in order to pre-select the best candidates for this demanding treatment. In a group of 21 patients, flow cytometric DNA ploidy provided the most accurate prediction, with a response rate of 88% in 8 DNA diploid tumors compared to 31% in 13 DNA aneuploid cases (P = 0.017) and a difference in overall survival of nine months (20.4 vs 11.3, P = 0.041). Only a slight trend towards improved response rate was observed when we immunohistochemically detected p53 anti-oncoprotein expression in 11 (52%) p53-positive tumors (P = 0.063). Other immunohistochemical biomarkers as P-glycoprotein (p170), p21/WAF, mdm2, c-erbB-2, and proliferative activity of tumor (detected either by anti-PCNA and anti-Ki67 monoclonal antibodies or as a flow cytometric proliferation index) were unrelated to the outcome of treatment. DNA ploidy and expression of p53 protein are potential biomarkers for predicting the response to regional chemotherapy of liver metastases from colorectal carcinoma.

Expression of p21WAF1/CIP1 in fetal and adult tissues: simultaneous analysis with Ki67 and p53

AIMS

To determine the expression of p21WAF1/CIP1 in relation to the expression of Ki67 and p53 in various normal adult and fetal tissues, and to investigate its distribution throughout the cell cycle.

METHODS

The expression of p21WAF1/CIP1 in relation to Ki67 and p53 was analysed in adult and fetal tissues using immunohistochemical techniques. Heat induced epitope retrieval techniques were used to characterise the presence of p21WAF1/CIP1 in different tissues, as well as to detect its distribution throughout the cell cycle. In addition, flow cytometry and western blotting were used to test whether the level of p21WAF1/CIP1 expression varied at different phases of the cell cycle in phytohaemagglutinin (PHA) stimulated lymphocytes.

RESULTS

p21WAF1/CIP1 expression varied from one tissue to another, and it was restricted mainly to the squamous and glandular epithelium, where it appeared in association with p53. Human tissues in which p21WAF1/CIP1 was found showed a mutually exclusive topographical sequential expression between p21WAF1/CIP1 and Ki67. This was confirmed by double labelling studies, which showed that p21WAF1/CIP1 positive cells were in the G0 phase. Unlike these findings of a decline in p21WAF1/CIP1 expression after the G0 phase, PHA stimulated lymphocytes showed a level of p21WAF1/CIP1 expression that rose as the cell progressed through the cell cycle.

CONCLUSIONS

The analysis of p21WAF1/CIP1 expression in relation to the status of p53 should take into account the existence of variable p21WAF1/CIP1 expression in different tissues. This could provide an explanation for the varying frequency of p53 mutations in tumours of different cellular origin. In tissues characterised by regular p21WAF1/CIP1 expression, it appears in a pattern that is consistent with the proposed role of this inhibitor of cyclin dependent kinases in cell cycle arrest-that of inducing cell differentiation. The conflicting results of in vivo and in vitro studies could support the hypothesis that microenvironmental conditions may influence the location of p21WAF1/CIP1 in different phases of the cell cycle.

Molecular abnormalities of the p53 pathway in dedifferentiated liposarcoma

Dedifferentiated liposarcoma represents a distinct subtype of liposarcoma and is characterized by the presence of abrupt transition from well-differentiated liposarcoma to high-grade pleomorphic sarcoma (mostly MFH-like). A key role for p53 in tumour progression of this subset of liposarcomas has been suggested on the basis of p53 immunopositivity. A series of 14 dedifferentiated liposarcomas has been investigated by analysing the p53 gene and protein together with the p53-related molecules p21Waf1 and mdm2, to verify whether the p53 pathway is involved in the development and progression of this tumour type. The results indicate that the p53 gene is rarely involved in dedifferentiated liposarcoma (7 per cent of cases analysed) and that low percentages of p53 immunopositivity are still compatible with integrity of the p53 gene. This concept is also supported by the observed preservation of p21Waf1 immunoreactivity in all but the p53-mutated cases. By contrast, mdm2 overexpression emerges as the most frequent abnormality in dedifferentiated liposarcoma (57 and 78 per cent of cases in well-differentiated and high-grade areas, respectively).