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

C16, a PKR inhibitor, suppresses cell proliferation by regulating the cell cycle via p21 in colorectal cancer

Double-stranded RNA-activated protein kinase R (PKR) is highly expressed in colorectal cancer (CRC). However, the role of PKR in CRC remains unclear. The aim of this study was to clarify whether C16 (a PKR inhibitor) exhibits antitumor effects and to identify its target pathway in CRC. We evaluated the effects of C16 on CRC cell lines using the MTS assay. Enrichment analysis was performed to identify the target pathway of C16. The cell cycle was analyzed using flow cytometry. Finally, we used immunohistochemistry to examine human CRC specimens. C16 suppressed the proliferation of CRC cells. Gene Ontology (GO) analysis revealed that the cell cycle-related GO category was substantially enriched in CRC cells treated with C16. C16 treatment resulted in G1 arrest and increased p21 protein and mRNA expression. Moreover, p21 expression was associated with CRC development as observed using immunohistochemical analysis of human CRC tissues. C16 upregulates p21 expression in CRC cells to regulate cell cycle and suppress tumor growth. Thus, PKR inhibitors may serve as a new treatment option for patients with CRC.

p21 as a Predictor and Prognostic Indicator of Clinical Outcome in Rectal Cancer Patients

The cell cycle plays a key and complex role in the development of human cancers. p21 is a potent cyclin-dependent kinase inhibitor (CDKI) involved in the promotion of cell cycle arrest and the regulation of cellular senescence. Altered p21 expression in rectal cancer cells may affect tumor cells' behavior and resistance to neoadjuvant and adjuvant therapy. Our study aimed to ascertain the relationship between the differential expression of p21 in rectal cancer and patient survival outcomes. Using tissue microarrays, 266 rectal cancer specimens were immunohistochemically stained for p21. The expression patterns were scored separately in cancer cells retrieved from the center and the periphery of the tumor; compared with clinicopathological data, tumor regression grade (TRG), disease-free, and overall survival. Negative p21 expression in tumor periphery cells was significantly associated with longer overall survival upon the univariate (p = 0.001) and multivariable analysis (p = 0.003, HR = 2.068). Negative p21 expression in tumor periphery cells was also associated with longer disease-free survival in the multivariable analysis (p = 0.040, HR = 1.769). Longer overall survival times also correlated with lower tumor grades (p= 0.011), the absence of vascular and perineural invasion (p = 0.001; p < 0.005), the absence of metastases (p < 0.005), and adjuvant treatment (p = 0.009). p21 expression is a potential predictive and prognostic biomarker for clinical outcomes in rectal cancer patients. Negative p21 expression in tumor periphery cells demonstrated significant association with longer overall survival and disease-free survival. Larger prospective studies are warranted to investigate the ability of p21 to identify rectal cancer patients who will benefit from neoadjuvant and adjuvant therapy.

ANXA13 promotes cell proliferation and invasion and attenuates apoptosis in renal cell carcinoma

Purpose

Emerging evidences have demonstrated that annexin A13 (ANXA13) is closely related to the occurrence and development of malignant tumors. However, the functions and underlying molecular mechanisms of ANXA13 in Clear cell renal cell carcinoma (ccRCC) have not been defined. Therefore, this study aimed to clarify the potential role of ANXA13 in regulating the proliferation, migration, invasion, cell cycle, and apoptosis of ccRCC cells.

Patients and methods

The quantitative real-time PCR (qRT-PCR) and western blotting was performed for detecting the ANXA13 expression in ccRCC tissues at the mRNA and protein levels, respectively. The GEPIA2 databases were used to derive data for analyzing the ANXA13 expression in pan-cancer and ccRCC clinical features. Cell Counting and colony formation assays, as well as flow cytometry, were used to detect cell proliferation, apoptosis, or cell cycle. The wound healing assay was used to evaluate the migration ability of cells, and the Trans-well assay was conducted to determine the cell invasiveness.

Results

ANXA13 was upregulated in ccRCC cells and human ccRCC tissues. Furthermore, siANXA13 inhibited ccRCC cell proliferation, migration, invasion and induced cell apoptosis.

Conclusion

ANXA13 was upregulated in ccRCC. ANXA13 promotes tumorigenic traits of ccRCC cell lines in vitro. ANXA13 is a potential novel biomarker and a potential therapeutic target in ccRCC.

How does intestinal-type intraductal papillary mucinous neoplasm emerge? CDX2 plays a critical role in the process of intestinal differentiation and progression

Intestinal-type intraductal papillary mucinous neoplasm (IPMN) of the pancreas is clinicopathologically distinctive. Our research aimed to elucidate the molecular mechanism of the development and progression of the intestinal-type IPMN. In 60 intestinal-type IPMN specimens, histological transitions from gastric-type epithelia to intestinal-type epithelia were observed in 48 cases (80%). CDX2/MUC2/alcian blue triple staining indicated that CDX2 appeared to precede MUC2 expression and subsequent alcian blue-positive mucin production. Expression of p21 and Ki-67 seemed to be accelerated by CDX2 expression (p = 6.02e-13 and p = 3.1e-09, respectively). p21/Ki-67 double staining revealed that p21 was mostly expressed in differentiated cells in the apex of papillae, while Ki-67 was expressed in proliferative cells in the base of papillae. This clear cellular arrangement seemed to break down with the progression of atypical grade and development of invasion (p = 0.00197). Intestinal-type IPMNs harbored frequent GNAS mutations (100%, 25/25) and RNF43 mutations (57%, 8/14) and shared identical GNAS and KRAS mutations with concurrent gastric-type IPMNs or incipient gastric-type neoplasia (100%, 25/25). RNF43 mutations showed emerging or being selected in intestinal-type neoplasms along with ß-catenin aberration. Activation of protein kinase A and extracellular-regulated kinase was observed in CDX2-positive intestinal-type neoplasm. These results suggest that gastric-type epithelia that acquire GNAS mutations together with induction of intrinsic CDX2 expression may evolve with clonal selection and additional molecular aberrations including RNF43 and ß-catenin into intestinal-type IPMNs, which may further progress with complex villous growth due to disoriented cell cycle regulation, acceleration of atypical grade, and advance to show an invasive phenotype.

Pattern of nucleotide variants of TP53 and their correlation with the expression of p53 and its downstream proteins in a Sri Lankan cohort of breast and colorectal cancer patients

Background

Breast cancer (BC) is known to be the most common malignancy in females whereas colorectal cancer (CRC) incidence also higher in both genders in Sri Lanka. TP53 is an important tumour suppressor gene and its somatic mutations are reported in approximately 27% of BC and 43% of CRC cases. Analysis of TP53 gene variants not only provides clues for the aetiology of the tumour formation, but also has an impact on treatment efficacy. The current study was conducted to investigate the pattern of TP53 variants in patients with BC and CRC from Sri Lanka.

Methods

30 patients with BC, 21 patients with CRC and an equal number of healthy controls were screened for mutational status of TP53 by polymerase chain reaction (PCR) followed by direct sequencing. In addition, a subset of these samples were analysed for the protein expression of p53 and comparison made with the mutational status of TP53. We also analysed the protein expression of p21 and MDM2 as potential indicators of p53 functional status and compared it with the protein expression of p53. Additionally, hotspot codons of the KRAS, BRAF and PIK3CA genes were also analysed in a subset of CRC patients.

Results

Twenty seven sequence variants, including several novel variants in the TP53 gene were found. Nine BC and seven CRC tumour samples carried pathogenic TP53 variants. Pathogenic point missense variants were associated with strong and diffuse positive staining for p53 by immunohistochemistry (IHC), whereas, wild type TP53 showed complete absence of positive IHC staining or rare positive cells, regardless of the type of cancer. There was no direct correlation between p21 or MDM2 expression and p53 expression in either BCs or CRCs. Four of the CRC patients had pathogenic hotspot variants in KRAS; three of them were on codon 12 and one was on codon 61.

Conclusion

The prevalence of pathogenic somatic TP53 variants was 31 and 33.33% in the studied BC and CRC cohorts respectively. All of them were located in exons 5–8 and the pathogenic missense variants were associated with strong immuno-positive staining for p53.

Expression of cell cycle regulators p21 and p27 as predictors of disease outcome in colorectal carcinoma

BACKGROUND

Recent studies suggest that aberrations in cell cycle checkpoint controllers are a common feature in human malignancies and predict prognosis independent of stage.

OBJECTIVES

This study correlated two cell cycle regulators (p27 and p21) with clinical and pathological variables in colorectal cancer (CRC) patients to assess their role as prognostic factors.

PATIENTS AND METHODS

A series of 65 CRC patients were analyzed for p27 and p21 expression in their tumors using immunohistochemistry.

RESULTS

Forty-six percent of tumors showed positive nuclear p27 expression, whereas 72% of cases were completely p21 negative. There were no significant correlations between p27 and p21 expression and gender, age, lymph node involvement, stage, and grade. However, p27 (but not p21) expression revealed highly significant correlation with tumor location (p < 0.01), depth of invasion (p < 0.03), and lympho-vascular invasion (p < 0.02). Tumors with high p27 expression showed a higher recurrence rate than tumors with no expression (p < 0.03). In Kaplan-Meier survival analysis, there was a significant (p = 0.046) difference in disease-free survival (DFS) between p27-positive and p27-negative tumors in favor of the latter. p21 did not show any predictive value of DFS (p < 0.7). Neither p27 nor p21 did predict disease-specific survival (DSS) in Kaplan-Meier analysis, but DSS time was much shorter for p27-positive tumors. In multivariate (Cox) model, p27 lost its value as independent predictor of DFS, and none of the covariates were independent predictors of DSS.

CONCLUSION

p27 expression seems to be more powerful than p21 expression in providing useful prognostic information in CRC, particularly in predicting the patients at high risk for recurrent disease. Larger cohort and longer follow-up are needed to fully elucidate the value of p27 (and p21) as independent predictors of disease outcome.

Expression of p21WAF1 in Astler-Coller stage B2 colorectal cancer is associated with survival benefit from 5FU-based adjuvant chemotherapy

In several, but not all, previous studies, positive p21^WAF1 expression has been suggested as an indicator of a good prognosis in patients with stage III/IV colorectal cancer. However, it is not known whether the same is true for stage B2 patients. The purpose of this study is to assess the influence of p21^WAF1 expression in tumor cells on disease-free survival (DFS) and overall survival (OS) of Astler–Coller stage B2 and C patients with colorectal cancer who underwent 5-fluorouracil-based adjuvant chemotherapy. Nuclear p21^WAF1 was detected by immunohistochemistry in tissue microarrays from 275 colorectal cancers. The expression of p21^WAF1 was associated with DFS (p = 0.025) and OS (p = 0.008) in the subgroup of stage B2 patients that was treated with adjuvant chemotherapy. In multivariate analysis, it remained the only independent prognostic parameter in relation to DFS and OS (p = 0.035 and p = 0.02, respectively). In the subgroup of 72 stage B2 patients with positive p21^WAF1 expression but not in the subgroup of 61 stage B2 patients with negative p21^WAF1 expression, adjuvant chemotherapy was associated with better DFS (85% 5-year survival versus 65% without chemotherapy, p = 0.03) and OS (96% versus 82%, p = 0.014). In the combined stage B2 and C group of patients treated with adjuvant chemotherapy, positive p21^WAF1 expression was also associated with better DFS and OS (p = 0.03, p = 0.002, respectively). Expression of p21^WAF1 in colorectal tumor cells identifies a subgroup of Astler–Coller stage B2 patients who could benefit significantly from 5FU-based chemotherapy and may improve the selection of patients for adjuvant chemotherapy.

The bone morphogenetic protein signaling pathway is upregulated in a mouse model of total parenteral nutrition

Total parenteral nutrition (TPN) results in intestinal mucosal atrophic changes due to an absence of enteral nutrition; however, the mechanisms responsible for this are not fully understood. It has been shown that bone morphogenetic protein (BMP) activation inhibits intestinal epithelial cell (EC) proliferation. Therefore, we hypothesized that the BMP pathway could be upregulated by TPN. To address this, we randomly assigned mice to receive TPN or to be enterally fed (control) for 7 d. Mucosal EC isolates were harvested from the entire length of small intestine for RNA and protein measurements. Full-thickness, mid-small bowel was processed for histological examination. TPN increased the abundance of BMP2, BMP4, and BMP type II receptor at the RNA and protein levels. Phosphorylation of Smad1, Smad5, and Smad8 also was greater in the TPN group than in the control, which helped to confirm activation of this pathway. Interestingly, the TPN and control groups did not differ in the mRNA expression of the extracellular soluble bmp antagonists, noggin, gremlin, chordin, or follistatin. Compared to the control group, the expression of c-Myc (cellular myelocytomatosis) mRNA was lower, whereas the level of p21(WAF1/CIP1) was greater, in the TPN group. Because the BMP family may function through suppression of Wnt-beta-catenin signaling, this pathway was also examined. mRNA expression of Wnt 3, Wnt5a, and the Wnt receptor Lrp5 were lower in the TPN group compared to controls. The results suggest that the BMP signaling pathway may be involved in the development of intestinal mucosal atrophy due to TPN administration.

Expression patterns of cyclins D1, E and cyclin-dependent kinase inhibitors p21waf1/cip1, p27kip1 in colorectal carcinoma: correlation with other cell cycle regulators (pRb, p53 and Ki-67 and PCNA) and clinicopathological features

Aberrations in the cell cycle regulators are common features of many tumours and several have been shown to have prognostic significant in colorectal cancer. The expression patterns of cyclins D1 and E as well as cyclin-dependent kinase (CDK) inhibitors p21waf1/cip1 and p27kip1 and their interrelationship with other cell cycle checkpoint proteins [p53, pRb, Ki-67 and proliferative cell nuclear antigen (PCNA)] were investigated in colorectal cancer in order to ascertain coregulation and influence on tumour behaviour or survival. These molecular markers were localisated immunohistochemically using the monoclonal antibodies anticyclin D1 (DCS-6), anticyclin E (13A3), anti-p21 (4D10), anti-p27 (1B4), anti-p53 (DO7), anti-Rb (AB-5), MIB1 and PC10 in colorectal cancer tissue from 97 patients. Data were analysed statistically using the spss software program. Overexpression of cyclin D1, cyclin E and p21waf1/cip1 proteins (>5% positive neoplastic cells) was observed in 5.9%, 30% and 7.2% of the cases respectively. Increased levels of cyclin D1 (p = 0.0001) and p21waf1/cip1 protein (p = 0.03) in tumours with mucous differentiation were observed. Overexpression of cyclin D1 was correlated with tumour stage (p = 0.03), the lymph node involvement (p = 0.02), as well as p21waf1/cip1 protein expression (p < 0.0001). Cyclin E was positively correlated with p21waf1/cip1 (p = 0.014), as well as with the cell proliferation as measured by PCNA-labelling index (p = 0.011) and Ki-67 score (p = 0.007). A positive relationship of p21waf1/cip1 expression with the proliferative-associated index Ki-67 was noted (p = 0.005). Downregulation of p27kip1 was observed in 47.4% of the cases and was correlated with downregulation of pRb (p = 0.002) and PCNA score (p = 0.004). The prognostic significance of cyclins D1, E and CDK inhibitors p21waf1/cip1, p27kip1 in determining the risk of recurrence and overall survival with both univariate (long-rang test) and multivariate (Cox regression) methods of analysis showed no statistically significance differences. In conclusion, these findings suggest that, the levels of the cell cycle regulators studied, do not seems to have a prognostic value, in terms of predicting the risk of early recurrence and overall survival. In addition, the interrelationships, probably means their contribution to the regulation of cell growth, through different pathways in colorectal carcinogenesis.

AP4 encodes a c-MYC-inducible repressor of p21

In the majority of human tumors, expression of the c-MYC oncogene becomes constitutive. Here, we report that c-MYC directly regulates the expression of AP4 via CACGTG motifs in the first intron of the AP4 gene. Induction of AP4 was required for c-MYC-mediated cell cycle reentry of anti-estrogen arrested breast cancer cells and mitogen-mediated repression of the CDK inhibitor p21. AP4 directly repressed p21 by occupying four CAGCTG motifs in the p21 promoter via its basic region. AP4 levels declined after DNA damage, and ectopic AP4 interfered with p53-mediated cell cycle arrest and sensitized cells to apoptosis induced by DNA damaging agents. AP4 expression blocked induction of p21 by TGF-beta in human keratinocytes and interfered with up-regulation of p21 and cell cycle arrest during monoblast differentiation. Notably, AP4 is specifically expressed in colonic progenitor and colorectal carcinoma cells. In conclusion, our results indicate that c-MYC employs AP4 to maintain cells in a proliferative, progenitor-like state.

Early carcinogenic events in HNPCC adenomas: differences with sporadic adenomas

BACKGROUND

Tumorigenesis in hereditary nonpolyposis colorectal cancer (HNPCC) differs from that in sporadic colorectal cancer during the early stage. We examined the expression of proliferation- and apoptosis-regulating proteins in relation to proliferation and apoptosis in HNPCC and sporadic adenomas.

METHODS

Proliferation and apoptosis were quantified, and the expression of cyclin B1, D3 and E, p21, p27, bcl-2, bax, p53 and cox-2 was determined by immunohistochemistry in 100 patients (42 with HNPCC and 48 with sporadic adenomas).

RESULTS

No differences between the two groups of patients in terms of proliferation and apoptosis were detected. Low-grade dysplastic HNPCC adenomas differed from sporadic ones by expressing bcl-2 more often (69 vs. 42%) and bax less often (50 vs. 73%). In comparison to sporadic adenomas, fewer high-grade dysplastic HNPCC expressed cyclin B1 and E (50 and 38% vs. 87 and 87%, respectively), p21 (6% vs. 53%) and bax (31% vs. 80%). In addition, HNPCC adenomas had a lower overexpression of p53 (5 vs. 19%).

CONCLUSION

The expression of cell cycle- and apoptosis-related proteins differs between HNPCC and sporadic adenomas from early through to advanced stages although proliferation and apoptosis are not different. These differences may contribute to the different clinical behavior of HNPCC and sporadic adenomas.

Bone morphogenetic protein signalling is required for the anti-mitogenic effect of the proteasome inhibitor MG-132 on colon cancer cells

BACKGROUND AND PURPOSE

Inhibition of proteasome has been emerging as a promising approach in pathway-directed cancer therapy. Bone morphogenetic protein (BMP) signalling, which is known to be regulated by the ubiquitin-proteasome pathway in osteoblasts, plays a crucial role in the suppression of gastrointestinal carcinogenesis. Here we sought to elucidate the anti-mitogenic effect of a proteasome inhibitor in relation to BMP signalling in colon cancer.

EXPERIMENTAL APPROACH

The effects of the proteasome inhibitor MG-132 on proliferation of SW1116 and HT-29 colon cancer cells were determined by [(3)H]-thymidine incorporation and colony-formation assay. The involvement of BMP signalling in the action of MG-132 was elucidated by western blot, real-time PCR, immunofluorescence and RNA interference.

KEY RESULTS

MG-132 significantly suppressed the proliferation of colon cancer SW1116 and HT-29 cells. In this regard, MG-132 activated BMP signalling and this was manifested as an increase in Smad1/5/8 phosphorylation and upregulation of p21(Waf1/Cip1) and p27(Kip1) expression. Knockdown of BMP receptor II abolished Smad1/5/8 phosphorylation, the induction of p21(Waf1/Cip1) and p27(Kip1) and inhibition of cell proliferation induced by MG-132. Further analysis revealed that MG-132 upregulated the expression of BMP1 and BMP2, which are secreted members of the BMP superfamily. Moreover, the expression of Smad6, an intracellular inhibitor of BMP signalling, was suppressed by MG-132.

CONCLUSIONS AND IMPLICATIONS

These findings suggest that inhibition of proteasome suppresses the proliferation of colon cancer cells via activation of BMP signalling. They also demonstrate a novel aspect of proteasome function in the regulation of colon cancer cell proliferation.

Further studies on the arrest of cell proliferation in tumor cells at the invading front of colonic adenocarcinoma

BACKGROUND AND AIM

The author has previously reported that neoplastic glands at the leading invading edge of colorectal carcinomas often display flat tumor cells and cellular gaps called glandular pores. The aim of this study was to audit cell proliferation and p53 mutation in flat tumor cells and in tumor cells at the tip of glandular pores at the leading invading front of colonic carcinomas.

METHODS

Sections from 40 colonic adenocarcinomas were immunostained with the proliferation marker Ki67 and with p53 protein. Expression was assessed at the leading invading front in consecutive neoplastic glands having flat tumor cells and epithelial pores and in neoplastic glands showing neither flat tumor cells nor glandular pores.

RESULTS

Flat tumor cells in neoplastic glands usually showed no Ki67 expression but overexpressed p53 mutation. In neoplastic glands with pores 40% of the tumor cells at the tip of the pores showed no Ki67, but they overexpressed p53 mutation.

CONCLUSIONS

The results showed, for the first time, that p53-positive flat neoplastic colonic cells arrest their proliferation at the invading front. It is possible that these p53-positive/Ki67-negative neoplastic cells were temporarily removed from the cell cycle (G0). This paradoxical biological behavior of tumor cells might be connected with the formation of glandular pores and appears to indicate that arrest of cell proliferation at the advancing tumor front in colonic carcinomas occurs independently of p53 mutation. The possible existence of two independent molecular systems at the advancing tumor edge of colonic carcinomas, one supervising cell proliferation and the other zealously transferring the p53 mutation to daughter cells, is suggested.

The role of the DNA damage checkpoint pathway in intraductal papillary mucinous neoplasms of the pancreas

PURPOSE

Intraductal papillary mucinous neoplasms (IPMN) are known to show a transition from adenoma to carcinoma accompanied by several molecular abnormalities. ATM-Chk2-p53 DNA damage checkpoint activation, which is involved in prevention of the progression of several tumors, was analyzed to evaluate the role of the DNA damage checkpoint in the progression of IPMNs.

EXPERIMENTAL DESIGN

One hundred and twenty-eight IPMNs were classified into four groups (intraductal papillary mucinous adenoma, borderline IPMN, noninvasive intraductal papillary mucinous carcinoma, and invasive intraductal papillary mucinous carcinoma) and stained immunohistochemically using antibody for Thr(68)-phosphorylated Chk2. Expression of ATM, Chk2, and p21(WAF1) and accumulation of p53 were also analyzed.

RESULTS

Chk2 phosphorylation was shown in all adenomas and showed a significant decreasing trend with the progression of atypia (P < 0.0001 by the Cochran-Armitage test for trend). Expression of p21(WAF1) also exhibited a decreasing tendency (P < 0.0001), reflecting DNA damage checkpoint inactivation. p53 accumulation was mostly detected in malignant IPMNs. It was suggested that the DNA damage checkpoint provides a selective pressure for p53 mutation.

CONCLUSION

Our findings indicate that DNA damage checkpoint activation occurs in the early stage of IPMNs and prevents their progression. It is suggested that disturbance of the DNA damage checkpoint pathway due to Chk2 inactivation or p53 mutation contributes to the carcinogenesis of IPMNs.

P21WAF1/CIP1 expression in colorectal carcinomas is related to Kras mutations and prognosis

BACKGROUND/AIM

P21WAF1/CIP1 is a cyclin-dependent kinase inhibitor activated by p53 to produce cell cycle arrest. A consensus has not been reached concerning the prognostic value of p21WAF1/CIP1 expression in colorectal cancers.

PATIENTS/METHODS

P21WAF1/CIP1 expression was determined immunohistochemically in a series of 211 cases of colorectal carcinomas, together with its relation to p53, bcl-2, cell turnover (as assessed by Ki67 expression and apoptotic counts) and the Kras gene status. The expression of p21WAF1/CIP1 was also compared with reference to clinicopathological parameters and patient survival.

RESULTS

The median value for nuclear p21WAF1/CIP1 expression was 31% (interquartile range, 13-47%) and the fraction of cases considered to be high expressers (>20%) was 66%. Expression of p21WAF1/CIP1 was not associated with immunoreactivity for p53 or bcl-2, or cell turnover. P21WAF1/CIP1 high-expressing tumors were more often well differentiated (P<0.001), node-negative (P=0.037), Dukes' B (P=0.027) and Kras gene-mutated cases (P=0.04). On univariate analysis, low p21WAF1/CIP1 expressers (<or=20%) had lower cancer-related survival as compared with high expressers (5-year survival, 56 vs. 70%; P=0.042). Lymph node status, liver metastasis and tumor size were also significant predictors. Multivariate analysis revealed lymph node-positive (P<0.001), liver metastasis (P<0.001), and low p21WAF1/CIP1 expression (P=0.017) to be independent predictors of short survival.

CONCLUSION

The regulation of p21WAF1/CIP1, independent of p53 or bcl-2 expression, appears to be associated with Kras mutations. The immunohistochemical detection of p21WAF1/CIP11 might thus be used to predict more precise outcome in colorectal cancer patients.

Distribution of neuronal apoptosis inhibitory protein in human tissues

The neuronal apoptosis inhibitory protein (NAIP) gene, also known as the baculovirus inhibitor of apoptosis repeat-containing protein 1 (BIRC1) gene, is a member of the inhibitors of apoptosis (IAP) family and was first characterized as a candidate gene for spinal muscular atrophy (SMA). The expression of NAIP has been thoroughly studied in the central nervous system and overlaps the pattern of neurodegeneration in SMA. Recent studies have pointed to a role for NAIP in non-neuronal cells. We report here the production of a specific anti-NAIP antibody and the profile of NAIP expression in human adult tissues by Western blot and immunohistochemical detection methods. NAIP was detected in a number of tissues by Western blot analysis, but immunohistochemistry revealed that NAIP's presence in certain tissues, such as liver, lung, and spleen, is most likely due to macrophage infiltration. In the small intestine, the expression of NAIP coincides with the expression of p21(WAF1). This observation, coupled with findings from other groups, suggests a role for NAIP in increasing the survival of cells undergoing terminal differentiation as well as the possibility that the protein serves as an intestinal pathogen recognition protein. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials.

p21 as a prognostic factor in non-small cell lung carcinomas

Few studies have focused on the correlation between p21 expression and survival for patients with non-small cell lung carcinoma (NSCLC), and the results are not consistent. We investigated the expression of p21 in 90 cases of NSCLC to evaluate the correlation between the p21 expression level and the clinicopathologic characteristics with patient survival. p21 was expressed in the nuclei of all the NSCLCs. The percentage of immunoreactive cells varied from 1% to 70%. All the patients were subdivided into a high and a low p21 expression group on the basis of the median percentage (17.05). There was no significant correlation between the p21 expression level and age, gender, histologic type, histologic grade, or stage. Using uni- and multivariate analyses, survival was significantly associated with gender, stage, and the p21 expression level. The survival rate for the high p21 expression group was higher than that for the low p21 expression group in the entire patient group, and especially for stage II and III patients, males, adenocarcinomas, or p53-positive tumors. Our findings showed that high p21 expression was an independent prognostic factor for NSCLC. p21 may be useful for determining the candidates for adjuvant therapies and also for selecting the appropriate chemotherapeutic agents.

Induction of the tumor-suppressor p16(INK4a) within regenerative epithelial crypts in ulcerative colitis

p16(INK4a) is a major tumor-suppressor protein, but its regulation and settings of fuction remain poorly understood. To explore the notion that p16 is induced in vivo in response to replicative stress, we examined p16 expression in tissues from human ulcerative colitis (UC; n = 25) and normal controls (n = 20). p16 was expressed strongly in UC-associated neoplasms (n = 17), as seen previously in sporadic colonic neoplasms. In non-neoplastic UC epithelium, p16 was expressed in 33% of crypts (the proliferative compartment) compared to < 1% of normal controls. p16 expression did not correlate with degree of inflammation but did correlate with the degree of crypt architecture distortion (P = .002)-a reflection of epithelial regeneration. In coimmunofluorescence studies with Ki67, p16 expression was associated with cell cycle arrest (P < .001). Both UC and normal crypts displayed evidence for the activation of the DNA damage checkpoint pathway, and p16 was induced in primary cultures of normal epithelial cells by ionizing irradiation (IR). However, induction by IR displayed delayed kinetics, implying that p16 is not an immediate target of the checkpoint pathway. These findings support a model in which p16 is induced as an "emergency brake" in cells experiencing sustained replicative stress.

Bottom-up cell proliferation with cyclin A and p27Kip1 expression in ulcerative colitis-associated dysplasia

To analyze the cell kinetics of ulcerative colitis (UC)-associated dysplasia, cyclin A, cyclin D1, cyclin E, cdk2, cdk4, p21(Waf1), and p27(Kip1) were immunohistochemically examined, in comparison with sporadic tubular adenomas. Immunohistochemical labeling indices for each marker in formalin-fixed paraffin-embedded tissue sections were assessed in a total of 23 low-grade dysplasias, 27 high-grade dysplasias, and 14 invasive adenocarcinomas associated with UC. For comparison, 21 sporadic tubular adenomas with low-grade dysplasia, 33 with high-grade dysplasia, and 21 invasive adenocarcinomas were also examined. In UC-associated dysplasias, cyclin A and p27(Kip1) were located in the lower parts of the crypts and p21(Waf1) in the upper regions. In tubular adenomas, cyclin A, cdk4, p27(Kip1), and p21(Waf1) were all expressed in the upper parts of the crypts. The expression levels of cyclin D1, cyclin E, and cdk2 were low. The cell proliferation zone in UC-associated dysplasia is located towards the bases of the crypts with the strong expression of cyclin A and p27(Kip1), in contrast to tubular adenomas, which have their cell proliferation zone in the upper parts of neoplastic crypts. It is considered that tumorigenesis with UC-associated dysplasia is of the bottom-up type, related to altered expression of cyclin A and p27(Kip1).

Immunohistochemical Detection of p27 and p21 Proteins in Canine Hair Follicle and Epidermal Neoplasms

Trichoblastomas, trichoepitheliomas, and squamous cell carcinomas in the skin of dogs were analysed by immunohistochemistry for the nuclear expression of p27, p21 and proliferating cell nuclear antigen (PCNA). High levels of p27 were present in trichoepitheliomas and trichoblastomas compared with squamous cell carcinomas. Detectable p21 was found in trichoepitheliomas and squamous cell carcinomas, but trichoblastomas had low level of p21 nuclear reactivity. Low levels of PCNA were detected in trichoepitheliomas and trichoblastomas compared with squamous cell carcinomas. The results suggested that nuclear p27 acts as a cyclin-dependent kinase (CDK) inhibitor in trichoepitheliomas and trichoblastomas. Nuclear p21 expression is involved in the induction of epithelial differentiation and seems to be unrelated to CDK inhibition.

The clinical significance of p53, p21, and p27 expressions in rectal carcinoma

Many checkpoint proteins that are involved in the control of the cell cycle and apoptosis have been investigated, but only a few studies have evaluated the prognostic significance of multiple factors only in rectal carcinomas. The aim of this study was to determine the role of p53, p21, and p27 protein expression as a prognostic factor in rectal carcinomas. Formalin-fixed, paraffin-embedded tissue blocks from 45 rectal adenocarcinomas with appropriate clinical and prognostic data were examined. The standard streptavidin-biotin immunoperoxidase method was used for immunostaining with p53 protein, p21 WAF1/Cip1 protein, and p27 Kip1 protein. The extent of positive p53, p21, and p27 staining was graded semiquantitatively. The clinicopathologic and prognostic features were statistically analyzed. No significant association was found between p53 status and p21 or p27 protein expression (chi2 test, P=0.42 and P=0.18 respectively). There was no correlation between the expressions of p53, p21, and p27, and conventional clinicopathologic features. The mean time interval to recurrence was 25.7+/-24.7 months (range, 0-54 months). p53, p21, and p27 expression was not associated significantly with recurrence and distant metastasis. However, a significant relationship was found between the expression of p27 protein and hepatic metastasis (independent samples t-test, P=0.007). The authors concluded that p53, p27, and p21 protein expression was not related to the clinicopathologic parameters, tumor aggressiveness, metastatic potential, and survival in rectal carcinomas. Further studies are needed to evaluate the predictors of outcome in rectal cancer, considering a variety of prognosticators.

HDM2 overexpression and focal loss of p14/ARF expression may deregulate the p53 tumour suppressor pathway in meningeal haemangiopericytomas. Study by double immunofluorescence and laser scanning confocal microscopy

AIMS

To investigate the p53 pathway in meningeal haemangiopericytomas (MHPCs), p14/ARF, p53 protein expression and two wild-type (wt) p53-induced proteins (HDM2 and p21/WAF1) were studied in 18 MHPCs, 11 primary, four of them recurrent on one, one, two and four occasions.

METHODS

Immunohistochemical detection of p14/ARF, p53, p21/WAF1, HDM2 and Ki67 proliferative index (PI) protein expression.

RESULTS

Ki67 index was > 5% in eight out 18 cases (44.4%). The PI in recurrent cases increased with neoplastic progression. Simultaneous p53 and wt p53 transactivated gene (p21/WAF, HDM2) expression occurred in all cases. This argues against p53 mutation. HDM2 overexpression was observed in 10 cases (55.5%). Double-immunofluorescence staining and laser scanning confocal microscopy (LSCM) displayed HDM2 and p53 colocalization. This strongly suggests that HDM2 binds and inactivates p53 that could be pathogenic for MHPCs, by a different mechanism than point mutation. p14/ARF expression > 5% was observed in 12 cases (66.6%). A normal (diffuse) pattern of expression was seen in 13 cases (72.2%). Focal loss of expression was observed in five patients (27.7%): three primary cases and two recurrences. Therefore, p14/ARF down-regulation may also contribute to the development of MHPC.

CONCLUSION

HDM2 overexpression, sometimes combined with focal loss of p14/ARF expression, may play a pathogenic role in MHPCs.

Immunohistochemical expression of cyclin D1, cyclin E, p21/waf1 and p27/kip1 in inflammatory bowel disease: correlation with other cell-cycle-related proteins (Rb, p53, ki-67 and PCNA) and clinicopathological features

BACKGROUND AND AIMS

The expression patterns of cyclins D1 and E as well as cyclin-dependent kinase inhibitors p21/waf1 and p27/kip1 and their correlation with clinical parameters and other cell cycle regulators was investigated in inflammatory bowel disease (IBD).

PATIENTS AND METHODS

These molecular markers were localized immunohistochemically using the monoclonal antibodies anti-cyclin D1 (DCS-6), anti-cyclin E (13A3), anti-p21 (4D10) and anti-p27 (1B4) in 70 patients with IBD, 30 patients with colorectal cancer and eight healthy subjects. Data were analyzed statistically using the software program.

RESULTS

Cyclin D1 expression was higher in both UC and CD compared with the healthy control group. In addition, CD cyclin D1 expression was higher compared with UC cases and colorectal carcinomas. Cyclin D1 expression was correlated with disease activity and cell proliferation in UC cases. A positive relationship of cyclin D1 with p27/kip1 in both UC and CD was detected. Cyclin E expression was higher in UC, CD and carcinomas compared with healthy control group and its expression correlated with proliferative activity in both UC and CD cases. p21/waf1 expression was higher in IBD cases compared with that of the control group, while a decreased p21/waf1 expression in the group of carcinomas was noted. This expression was correlated with disease activity in UC and the proliferative activity in both UC and CD. The expression of cyclins D1 and E as well as p21/waf1 was also correlated with the existence of dysplastic lesions. A lower p27/kip1 expression in the group of carcinomas compared with IBD cases and healthy controls was found.

CONCLUSIONS

The expression patterns of cyclin D1, cyclin E, p21/waf1 and p27/kip1 in IBD may indicate their contribution in epithelial cell turnover and their possible implication in IBD-related dysplasia-carcinoma.

P21WAF1/Cip1 gene expression in primary human hepatocellular carcinoma and its relationship with P53 gene mutation

P21WAF1/Cip1, an inhibitor of cyclin-dependent kinases, is a critical downstream effector in the P53-specific pathway of growth control. Increased expression of P21WAF1/Cip1 has been found to reflect the status of the P53 tumor-suppressor pathway. We investigated the expression of P21WAF1/Cip1 in a relatively small, but well-characterized group consisting of 28 hepatocellular carcinomas. The samples were previously studied for P53 gene mutation. P21WAF1/Cip1 expression were identified by in situ hybridization and immunohistochemistry. Positive ISH for P21WAF1/Cip1 transcripts was found in 18 of 28 cases (64.3%). All positive cases by ISH showed detectable P21WAF1/Cip1 protein reactivity by IHC. No relationship was found between P21WAF1/Cip1 staining and P53 mutational status. No associations were seen with tumor metastasis, size and tumor grade, except for tumor differentiation status which showed higher frequency of P21WAF1/Cip1 expression in moderate-well differentiated HCCs than poorly differentiated tumors (P < 0.05). It is concluded that expression of P21WAF1/Cip1 is common in HCCs, but does not correlate with P53 mutational status or pathological parameters investigated except for tumor differentiation. Also, there may be other factors beside P53 that regulate P21WAF1/Cip1 gene expression in HCCs.

Vitamin D2 analog 19-nor-1,25-dihydroxyvitamin D2: antitumor activity against leukemia, myeloma, and colon cancer cells

BACKGROUND

1,25-Dihydroxyvitamin D(3) inhibits growth of several types of human cancer cells in vitro, but its therapeutic use is hampered because it causes hypercalcemia. 19-nor-1,25-Dihydroxyvitamin D(2) (paricalcitol) is a noncalcemic vitamin D analog that is approved by the Food and Drug Administration for the treatment of secondary hyperparathyroidism. We investigated the antitumor activity and mechanism of action of paricalcitol in vitro and in vivo.

METHODS

Effects of paricalcitol on proliferation, the cell cycle, differentiation, and apoptosis were examined in cancer cell lines. Effects on tumor growth were examined with colon cancer cell xenografts in nude mice (five in the experimental group and five in the control group). The interaction of paricalcitol with the vitamin D receptor (VDR) in mononuclear spleen cells and myeloid stem cells from wild-type and VDR knockout mice was examined. All statistical tests were two-sided.

RESULTS

Paricalcitol inhibited the proliferation of myeloid leukemia cell lines HL-60, NB-4, and THP-1 cells at an effective dose that inhibited growth 50% (ED(50)) of 2.4-5.8 x 10(-9) M by inducing cell cycle arrest and differentiation. Paricalcitol inhibited the proliferation of NCI-H929 myeloma cells at an ED(50) of 2.0 x 10(-10) M by inducing cell cycle arrest and apoptosis. Paricalcitol also inhibited the proliferation of colon cancer cell lines HT-29 (ED(50) = 1.7 x 10(-8) M) and SW837 (ED(50) = 3.2 x 10(-8) M). HT-29 colon cancer xenografts in paricalcitol-treated nude mice were smaller (1044 mm(3) and 1752 mm(3), difference = 708 mm(3), 95% confidence interval = 311 to 1104 mm(3); P =.03) and weighed less (1487 mg and 4162 mg, difference = 2675 mg, 95% confidence interval = 2103 to 3248 mg; P<.001) than those in vehicle-treated mice. Paricalcitol induced committed myeloid hematopoietic stem cells from wild-type but not from VDR knockout mice to differentiate as macrophages.

CONCLUSION

Paricalcitol has anticancer activity against myeloid leukemia, myeloma, and colon cancer cells that may be mediated through the VDR. Because it has been approved by the Food and Drug Administration, clinical trials of this agent in certain cancers are reasonable.

The homeobox gene Cdx1 belongs to the p53-p21(WAF)-Bcl-2 network in intestinal epithelial cells

Because the Cdx1 homeobox gene stimulates proliferation and induces transformation and tumorigenesis, it has been investigated whether it is involved in the complex network comprising p53, p21(WAF), and Bcl-2 in intestinal epithelial cells. Non-transformed intestinal IEC-6 cells and colon adenocarcinoma SW480 cells were used to study the putative molecular relationship between Cdx1, p53, p21(WAF), and Bcl-2. Wild-type p53 inhibited the transcriptional activity of the Cdx1 promoter whereas the inactive mutant p53(mut22/23) had no effect. Induction of Cdx1 expression had no direct effect on p53 expression and activity. However, it inhibited the transcriptional activity of the p21(WAF) promoter through Cdx1 binding to the p21(WAF) TATA-box and increased the transcriptional activity of the Bcl-2 promoter P2 through a consensus Cdx-binding site. Finally, compared to control cells, Cdx1-overexpressing cells were more resistant to adriamycin-induced apoptosis, probably because they do not show concomitant decrease in endogenous Bcl-2 level. In conclusion, Cdx1 is a negatively regulated target of p53 in intestinal cells. Its regulation of p21(WAF) and Bcl-2 is opposite to that of p53 and is p53-independent. Cdx1 belongs to the regulatory networks of apoptosis, proliferation, and differentiation. These results emphasize the oncogenic potential of Cdx1.

The antiproliferative activity of aloe-emodin is through p53-dependent and p21-dependent apoptotic pathway in human hepatoma cell lines

The aim of this study is to investigate the anticancer effect of aloe-emodin in two human liver cancer cell lines, Hep G2 and Hep 3B. We observed that aloe-emodin inhibited cell proliferation and induced apoptosis in both examined cell lines, but with different the antiproliferative mechanisms. In Hep G2 cells, aloe-emodin induced p53 expression and was accompanied by induction of p21 expression that was associated with a cell cycle arrest in G1 phase. In addition, aloe-emodin had a marked increase in Fas/APO1 receptor and Bax expression. In contrast, with p53-deficient Hep 3B cells, the inhibition of cell proliferation of aloe-emodin was mediated through a p21-dependent manner that did not cause cell cycle arrest or increase the level of Fas/APO1 receptor, but rather promoted aloe-emodin induced apoptosis by enhancing expression of Bax. These findings suggest that aloe-emodin may be useful in liver cancer prevention.

High apoptotic activity and low epithelial cell proliferation with underexpression of p21(WAF1/CIP1) and p27Kip1 of mucinous carcinomas of the colorectum: comparison with well-differentiated type

We comparatively assessed 41 mucinous colorectal carcinomas (MUCs) and 620 non-MUC (well-, moderately, and poorly differentiated adenocarcinoma) cases for clinicopathologic findings; and 41 MUCs and 115 randomly selected non-MUCs also were studied for the following: (1) apoptotic activity and Ki-67 immunoreactivity; (2) immunohistochemical expression of p21(WAF1/CIP1), p27Kip1, p53, and bcl-2; and (3) c-Ki-ras mutations. The rates for lymph node involvement and peritoneal dissemination were higher in MUCs than in non-MUCs. Multivariate analysis showed MUCs to have a worse prognosis than well-differentiated adenocarcinomas. The Ki-67 labeling for MUCs was significantly lower than that for non-MUCs, whereas the apoptotic index was significantly higher than for the well-differentiated type. The labeling for p21(WAF1/CIP1) and p27Kip1 was lower in MUCs (2.7% and 35.3%, respectively) than in well-differentiated adenocarcinomas (4.2% and 48.6%, respectively). MUCs can be considered a different tumor from the well-differentiated type, with a poor prognosis owing to frequent lymph node metastasis and peritoneal dissemination, and characterized by high apoptotic and low proliferative activities associated with low p21(WAF1/CIP1) and p27Kip1 expression.

Sodium butyrate modulates cell cycle-related proteins in HT29 human colonic adenocarcinoma cells

Sodium butyrate (NaB), a product of colonic fermentation of dietary fibre, has been shown to inhibit cell proliferation by blocking cells in the G0/G1 phase of the cell cycle through a mechanism of action still not completely understood. We investigated the effect of NaB on the level of some G1 phase-related proteins in a colon carcinoma cell line (HT29). In particular, we addressed our attention to cyclin D1 (the key regulator of G1S progression), p21waf1/cip1 (the main inactivator of the cyclin D/cdk complex), and p53 (the most important regulator of p21waf1/cip1 gene transcription). At inhibitory concentrations (higher than 1 mM) NaB reduced cyclin D1 and p53 level in a dose-dependent manner and sustained the synthesis of p21waf1/cip1, probably in a p53-independent way, accounting for the G0/G1 block observed by flow cytometry. Present results provide further evidence on the molecular mechanism at the basis of the physiological role of NaB and support the hypothesis that an unbalanced diet, poor in carbohydrates and therefore in NaB, could result in functional alterations with clinical and carcinogenic implications.

P21 (WAF1) expression in colorectal cancer: correlation with P53 and cyclin D1 expression, clinicopathological parameters and prognosis

P21 (WAF1), P53 and cyclin D1 belong to the cell cycle-regulating family of proteins, and the loss of activity of proteins P53 and P21 (WAF1) seems to be one of the most important regulatory mechanisms of carcinogenesis in colorectal cancer. The purpose of this study was to assess the relationship between P21 (WAF1), P53 and cyclin D1 immunoreactivity, and to evaluate the prognostic significance of their expression. Tissue sections from 122 paraffin-embedded colorectal carcinomas were immunostained with monoclonal antibodies. Positivity for P21 (WAF1) was found in 48 cases (39%), positivity for P53 in 96 cases (70%) and positivity for cyclin D1 in all the cases (100%). Statistical analyses revealed a statistically significant inverse correlation between P53 and P21 (WAF1)-immunopositivity and between P21 (WAF1)-immunopositivity and the degree of cyclin D1-immunopositivity, as well as an inverse correlation between P21 (WAF1) expression and clinical stage. In univariate analysis, down-regulation of P21 (WAFI) expression was associated with poor prognosis, but multivariate analysis did not confirm its independent prognostic significance. In Cox's analysis only regional lymph node invasion and hepatic metastases were proven as independent prognostic parameters. Our investigation results suggest that in colorectal cancer, the induction of P21 (WAF1) may occur mostly in a P53-dependent pathway. P21 (WAF1), as the main cyclin-dependent kinase (CDK)-inhibitor, may also inhibit the activity of cyclins such as cyclin D1.

An immunohistochemical study of p21 and p53 expression in primary node-positive breast carcinoma

AIMS

p21, an inhibitor of cyclin-dependent kinase, is involved in the p53 pathway of growth control. Its expression has been linked to cellular differentiation. It has been implicated in p53-mediated growth arrest following DNA damage and in terminally differentiated cells. This study analysed p21 and p53 expression, in a series of node-positive patients with breast carcinoma and examined histopathological parameters of the tumour and the prognostic implications of p21 and p53 expression.

METHODS

One hundred and five consecutive patients with node-positive disease and at least 3 years follow-up were identified. Sections were stained for p53 and p21 using monoclonal antibodies. Results were expressed as percentage positive cells, and over 20% considered positive for p53 and over 10% considered for p21.

RESULTS

p21 was overexpressed (>10% of cells positive) in 65% of patients and p53 was overexpressed (>20% of cells positive in 68%. The mean (SEM) level of p21 staining was 5.7(0.8)% and was 54.9(4.0)% for p53. There was no correlation between p21 and p53 expression (r=0.071 P=0.5). There were no significant differences in demographic criteria between patients that were p21 positive or negative and p53 positive or negative. There were no significant differences in tumour type, grade or stage between the groups. p21 expression did not have prognostic significance; however, p53 positivity was associated with a worse prognosis, which remained when controlled for stage.

CONCLUSIONS

This study demonstrated p21 overexpression in 65% of patients with node-positive breast carcinoma. Levels did not correlate with p53 status and unlike p53 failed to have prognostic significance.

Patterns of p21(waf1/cip1) expression in non-papillomatous nasal mucosa, endophytic sinonasal papillomas, and associated carcinomas

AIMS

To clarify p21(waf1/cip1) expression in sinonasal lesions.

METHODS

Archived surgical specimens from 38 patients were investigated by means of immunohistochemistry. p21(waf1/cip1) staining was evaluated in the different layers of the epithelium. In addition, human papillomavirus (HPV) infection and p53 protein overexpression were assessed and correlated with p21(waf1/cip1) expression.

RESULTS

p21(waf1/cip1) staining was negative in non-papillomatous nasal mucosa. HPV infection and p53 protein overexpression were not seen. Sixteen of 20 inverted papillomas showed p21(waf1/cip1) expression. HPV infection was found in 16 cases and p53 protein overexpression was present in 13 specimens. Expression of p21(waf1/cip1) was restricted to surface cells in five cases, but involved basal/parabasal cells in 11 specimens. Immunoreactivity for p21(waf1/cip1) in basal/parabasal cells colocalised with p53 protein overexpression. Enhanced expression rates for p21(waf1/cip1) were seen in transitional and squamous epithelium compared with columnar epithelium. p21(waf1/cip1) expression involved only surface cells in cylindrical cell papillomas. HPV infection and p53 protein overexpression were detected in all specimens. One of five squamous cell carcinomas showed p21(waf1/cip1) expression. HPV infection was seen in two cases, and all carcinomas showed p53 protein overexpression.

CONCLUSIONS

Expression of p21(waf1/cip1) is associated with terminal differentiation in surface cells in inverted papillomas and cylindrical cell papillomas, but not in non-papillomatous nasal mucosa. Overexpression of p53 protein colocalises with p21(waf1/cip1) expression in basal/parabasal cells in inverted papillomas but not in cylindrical cell papillomas. Expression of p21(waf1/cip1) in squamous cell carcinomas involves a subset of tumours with p53 protein overexpression.

p53 Mutation in adenocarcinoma arising in retrorectal cyst hamartoma (tailgut cyst): report of 2 cases--an immunohistochemistry/immunoperoxidase study

Retrorectal cyst hamartoma (RCH) is a rare benign cystic lesion located in the retrorectal space. Malignancy arising in such lesions is very uncommon. In this study, 2 cases of mucinous adenocarcinoma arising in RCH are presented. In one case, dysplastic epithelium lined the cyst wall, surrounding the area of carcinoma and suggesting a dysplasia-carcinoma progression in RCH. Adenocarcinoma and the dysplastic epithelium were strongly positive for p53 and Ki-67 and showed negative staining for p21 by immunohistochemistry. These findings are suggestive of a mutation in the p53 gene in the adenocarcinoma and in dysplastic epithelium lining the cysts, similar to the dysplasia-carcinoma sequence described for the development of colonic adenocarcinoma.

Expression of p21(WAF1/CIP1) and p53 proteins in gastric carcinoma: its relationships with cell proliferation activity and prognosis

The expressions of p21(WAF1/CIP1), p53 proteins, and Ki-67 antigen were investigated immunohistochemically in 190 primary gastric carcinomas. Of the 190 tumors, 40.5% positively expressed p21(WAF1/CIP1) and 42.1% positively expressed p53. The expression of p21(WAF1/CIP1) was significantly associated with clinicopathological factors including gender, tumor size, status of lymph node, and clinicopathological stage (P<0.05 for all), but p21(WAF1/CIP1) expression showed no clear correlation with Ki-67 labeling index. The mean Ki-67 labeling index was significantly higher in p53-positive cases than p53-negative cases (P<0.0001). However, among the clinicopathological factors examined, expression of p53 correlated only with age. Univariate and multivariate survival analyses revealed that clinicopathological stage (P<0.001) and expression status of p21(WAF1/CIP1) (P<0.05) were independent prognostic factors. Neither the expression status of p53 nor the Ki-67 labeling index, however, influenced the prognosis of patients with gastric cancer.

p63, a p53 homologue, is a selective nuclear marker of myoepithelial cells of the human breast

Myoepithelial cells (MCs) constitute the basal cell layer of normal mammary epithelia, and their identification is of particular diagnostic value because they are retained in most benign lesions while being lost in malignancy. Several MC immunocytochemical markers are currently available for diagnostic purposes, with special reference to smooth muscle-related antigens. p63 is a member of the p53 gene family, and its germline mutations are associated with severe mammary developmental defects in both rodents and humans. Different p63 isoforms have been identified, some of which (DeltaNp63) are preferentially expressed in the epithelial basal cells of different organs and have been considered as possible markers of stem cells/reserve cells. We investigated immunohistochemically 384 samples of normal and diseased human breast, including 300 invasive carcinomas, using four antibodies recognizing all p63 isoforms, or the DeltaNp63 isoforms. Twenty cytologic specimens were also investigated. Furthermore, snap-frozen tissue samples from three fibroadenomas and 10 invasive ductal carcinomas with their paired non-neoplastic tissues and three corresponding lymph node metastases were evaluated for the expression of p63 mRNA by RT-PCR. In normal breast tissue p63 immunoreactivity was confined to the nuclei of MCs. In all benign lesions p63-immunoreactive cells formed a continuous basal rim along the epithelial structures. Stromal cells, and in particular myofibroblasts, were consistently unreactive. Adenomyoepitheliomas showed nuclear staining in most neoplastic cells. A peripheral rim of p63-immunoreactive cells was retained surrounding lobular and ductal carcinoma in situ, although it was discontinuous as opposed to the normal structures. Invasive breast carcinomas were consistently devoid of nuclear p63 staining, with the exception of the two adenoid-cystic carcinomas, of the two ductal carcinomas with squamous metaplasia, and of 11 (4.6%) ductal carcinomas not otherwise specified, showing p63 immunoreactivity in a minor fraction (5-15%) of the neoplastic cells. In comparison with other MC markers, p63 was the most specific, being restricted exclusively to MCs, whereas antibodies to smooth muscle actin and, to a lesser extent, calponin also decorated stromal myofibroblasts. In the cytologic preparations p63 immunoreactivity was a consistent feature of "naked nuclei" and of a subset of cells surrounding benign epithelial clusters. RT-PCR experiments with primers specific for different p63 isoforms documented that normal tissues and fibroadenomas preferentially expressed the DeltaNp63 isoforms. Our study demonstrates that in normal and pathologic breast tissues MCs consistently express the DeltaNp63 isoforms. We suggest p63 as a reliable, highly specific, and sensitive MC marker in both histologic and cytologic preparations. Furthermore, because p63 immunoreactivity in adult epithelia is normally restricted to progenitor cells, it can be speculated that it might be a clue for the identification of the still elusive breast progenitor cells.

Molecular predictors of survival after adjuvant chemotherapy for colon cancer

BACKGROUND

Adjuvant chemotherapy improves survival among patients with stage III colon cancer, but no reliable molecular predictors of outcome have been identified.

METHODS

We evaluated loss of chromosomal material (also called loss of heterozygosity or allelic loss) from chromosomes 18q, 17p, and 8p; cellular levels of p53 and p21(WAF1/CIP1) proteins; and microsatellite instability as molecular markers. We analyzed tumor tissue from 460 patients with stage III and high-risk stage II colon cancer who had been treated with various combinations of adjuvant fluorouracil, leucovorin, and levamisole to determine the ability of these markers to predict survival.

RESULTS

Loss of heterozygosity at 18q was present in 155 of 319 cancers (49 percent). High levels of microsatellite instability were found in 62 of 298 tumors (21 percent), and 38 of these 62 tumors (61 percent) had a mutation of the gene for the type II receptor for transforming growth factor beta1 (TGF-beta1). Among patients with microsatellite-stable stage III cancer, five-year overall survival after fluorouracil-based chemotherapy was 74 percent in those whose cancer retained 18q alleles and 50 percent in those with loss of 18q alleles (relative risk of death with loss at 18q, 2.75; 95 percent confidence interval, 1.34 to 5.65; P=0.006). The five-year survival rate among patients whose cancer had high levels of microsatellite instability was 74 percent in the presence of a mutated gene for the type II receptor for TGF-beta1 and 46 percent if the tumor did not have this mutation (relative risk of death, 2.90; 95 percent confidence interval, 1.14 to 7.35; P=0.03).

CONCLUSIONS

Retention of 18q alleles in microsatellite-stable cancers and mutation of the gene for the type II receptor for TGF-beta1 in cancers with high levels of microsatellite instability point to a favorable outcome after adjuvant chemotherapy with fluorouracil-based regimens for stage III colon cancer.

Increased expression of WAF1 in intrahepatic bile ducts in primary biliary cirrhosis relates to apoptosis

BACKGROUND/AIMS

In primary biliary cirrhosis (PBC), the intrahepatic small bile ducts are selectively damaged by immune attacks, followed by progressive loss mainly due to apoptosis. Compared to the intercellular signaling such as the CD95/CD95 ligand interaction, little is known about alterations in intracellular cell cycle regulatory proteins and genotoxic damage in this apoptotic process. WAF1 is a potent and reversible inhibitor of cell cycle progression at both the G1 and G2 checkpoint and upregulated WAF1 induces irreversible G1 arrest and apoptosis. Transcriptional activation of the WAF1 gene is induced by the upregulated p53 in response to DNA damage. In this study, the cell cycle regulatory process of apoptosis in PBC was examined with respect to expression of WAF1.

METHODS

Immunostaining for WAF1 and p53 was performed using 11 liver sections of PBC and 26 control livers. In addition, Ki67, apoptosis (TUNEL-positive), and human telomerase RNA (hTR) were also detected.

RESULTS

WAF1 was expressed in the nuclei of several epithelial cells in most damaged bile ducts in PBC but infrequently or rarely in controls. Some of these cells were also positive for p53, while the remainder were not. Ki67 immunostaining and TUNEL disclosed that the bile ducts in PBC showed increased cell division as well as enhanced apoptosis. Immunostaining of Ki67 and TUNEL staining showed that WAF1-positive cells were not proliferating, while some WAF1-positive cells were undergoing apoptosis. Moreover, the bile ducts lacked hTR expression, implying progressive shortening of telomeres during increased cell divisions.

CONCLUSIONS

It seems possible that in PBC, expression of WAF1 on biliary epithelial cells relates to the apoptosis. p53 may be involved in this upregulation. This may be due to physiological upregulation of WAF1 and p53 in response to genotoxic damage such as oxidative stress associated with cholangitis, suggesting other processes than CD95/CD95 ligand interaction in biliary epithelial apoptosis in PBC.

Quantitative p21(waf-1)/p53 immunohistochemical analysis defines groups of primary invasive breast carcinomas with different prognostic indicators

We used image cytometry to quantify the immunohistochemical expression of p21(waf-1) and p53 in primary breast carcinoma. Ratio analysis of the quantified p53/p21(waf-1) protein expression allowed us to define 3 groups of carcinomas, each characterized by specific pathological and biological profiles. The negative (NEG) group, characterized by negligible expression of both proteins, comprised small-sized, low-grade tumors associated with high contents of hormonal receptors and low growth fraction. In the NEG group, Ki-67 labelling index area (%LIa) was the only significant prognostic indicator. The P53H group, characterized by prevalence of p53 %LIa, was constituted by large-sized, high-grade tumors showing low hormonal receptor contents and high growth fraction. In the P53H group, both p53 and Ki-67 were inversely associated with both estrogen receptor (ER) and progesterone receptor (PGR), suggesting that extensive p53 immunostaining is related to poor differentiation and high proliferation. Only N status was prognostically significant in the P53H group. The P21H group, characterized by prevalence of p21(waf-1) %LIa, displayed intermediate pathological and biological features. A significant association between p53 and p21(waf-1) expression suggested functional stabilization of wtp53 and therefore possible DNA damage-dependent G1/S arrest (genetic instability) in the P21H group; P21(waf-1)expression was significantly associated with the presence of node metastasis. Patients in the P21H group had a higher recurrence rate and a shorter disease-free time interval from surgery with respect to the NEG group. Proportional hazard regression analysis disclosed Ki-67 %LIa and, to a lesser degree, PGR %LIa as significant relapse-free survival prognostic indicators.

[Expression of p21 WAF1/CIP1 protein in colorectal cancers: study of its relation to p53 mutation and Ki67 antigen expression]

Mutations of the p53 gene are the most common genetic alteration in malignant human tumors. A cyclin-dependent kinase inhibitor, p21WAF1/CIP1, is thought to be an important mediator of p53-induced cell cycle arrest. Although numerous studies have reported p53 expression and mutation in colorectal cancer few of them have correlated p53 expression with that of its downstream effector p21 and with the proliferation index as measured by expression of the Ki67 nuclear antigen. We studied p53, p21 and Ki67 expression by immunohistochemistry and molecular biology in 35 colorectal carcinomas. We compared these findings with each other and with clinical factors. Sixty three percent of tumors expressed p53 whereas seventy one percent expressed p21WAF1/CIP1. In adenocarcinomas, p21 staining was heterogeneous: p21-reactive cells were seen in the most differentiated areas. There was no correlation between p21WAF1/CIP1 and p53 expression, p53 mutation, Ki67 expression or clinical factors such as sex or location of the tumor. On the other hand, there was a statistical relationship between p21 expression and survival: our results indicated an association between high p21 expression and lower stages p21WAF1/CIP1 appears to be induced independently of p53 in these tumors and may be associated with differentiation rather than proliferation.

Clinical relevance of immunohistochemical expression of p53-targeted gene products mdm-2, p21 and bcl-2 in breast carcinoma

The present study was designed to investigate the clinical/prognostic relevance of immunohistochemical expression of p53-targeted genes mdm-2, p21WAF1 and bcl-2 alone and in combination with p53 for the indirect assessment of p53 gene status in breast cancer. 141 archival breast carcinomas were immunostained, and the putative mutational status of the p53 gene was defined in 21 of them, as a control for immunohistochemistry, using the polymerase chain reaction single-strand conformational polymorphism (PCR-SSCP) analysis. Genetic changes of p53 correlated significantly with p53 protein overexpression (p = 0.01) but did not do so with any of the related molecules. Immunohistochemical p53 status was directly correlated with mdm-2 (p = 0.0001), p21 (p = 0.0004) and inversely with bcl-2 (p = 0.005) expression. bcl-2 proved to be an independent marker of prognosis, p53 only in the group of node-positive carcinomas, whereas bcl-2-/p53+ tumours revealed the worst prognosis. Mdm-2 and p21 expression was of prognostic significance neither alone nor in combination. We conclude that the detection of down-stream regulators of p53 does not increase the efficacy of immunohistochemistry in assessing the functional status of p53 in breast cancer; however, their combined analysis may help to select subgroups of patients at the extremes of risk for recurrence, or those with greater chances for survival.

Expression of p21Waf1, p27Kip1 and cyclin D1 proteins in breast ductal carcinoma in situ: Relation with clinicopathologic characteristics and with p53 expression and estrogen receptor status

p21Waf1 (p21), p27Kip1 (p27) and cyclin D1 have recently been reported as useful prognostic markers for patients with breast carcinoma. However, studies on these cell cycle regulators in ductal carcinoma in situ (DCIS) have been extremely limited. Therefore, we studied the immunohistochemical expression of p21, p27 and cyclin D1 proteins in 49 DCIS cases and compared the findings with the clinicopathologic parameters (age, tumor size, gross type, histologic type, histologic grade, necrosis and mitotic index), p53 and estrogen receptor (ER) status. A significant correlation was found between positive p21 immunoreactivity (67.3% of the cases) and well-differentiated histologic grade, non-comedo type, ER-positive and p53-negative (p53-) status. DCIS with p21+/p53- is likely to be the non-comedo type. The overexpression of cyclin D1 (59.2% of the cases) correlated positively with the ER expression (P = 0.001). The p27 protein expression (46.9% of the cases) correlated with the cyclin D1 immunopositivity (P = 0.0003) and ER expression (P = 0.005). No significant associations were seen in the p27 or cyclin D1 expression and other clinicopathologic parameters. Our results suggest that p21 might be more related to the useful biologic markers in DCIS than p27 or cyclin D1. The significant positive association between p21, p27 or cyclin D1 and ER status, and close association of p27 and cyclin D1 expression might be implicated in the tumor biology of DCIS.

Increased expression of cyclin D1, cyclin E and p21(Cip1) associated with decreased expression of p27(Kip1) in chemically induced rat mammary carcinogenesis

We induced rat mammary tumors in 7-week-old female Sprague-Dawley rats by intragastric administration of 7,12-dimethylbenz(a)anthracene (DMBA), and analyzed by immunohistochemistry the expression of cyclin D1, cyclin E, p21(Cip1), and p27(Kip1) in carcinomas, atypical tumors, and benign tumors as well as normal mammary glands from the control group. Proliferation status was assessed by immunohistochemistry using bromodeoxyuridine (BrdU). A sequential increase in cyclin D1-, cyclin E-, and p21(Cip1)-positive epithelial cells was observed from normal mammary glands, to atypical tumors, to carcinomas. In contrast, carcinomas showed a significantly lower number of epithelial cells immunoreactive to p27(Kip1) when compared with atypical tumors, benign tumors and normal mammary glands. The immunoreactivities of BrdU, cyclin D1, cyclin E, and p21(Cip1) were positively correlated, whereas that of p27(Kip1) appeared inversely correlated to those of the others. Reverse transcriptase-polymerase chain reaction (RT-PCR) and western blot analysis were also performed to determine the mRNA and protein levels of cyclins and cyclin-dependent kinase inhibitors in tumors and normal mammary glands. The protein levels for cyclin D1, cyclin E and p21(Cip1) in carcinomas and atypical tumors were significantly higher than those in benign tumors, while normal mammary glands showed negligible expression. On RT-PCR, tumors showed higher mRNA levels of cyclin D1 and cyclin E than those of normal mammary glands. Our results suggest that rat mammary carcinogenesis involves increased expression of cyclin D1, cyclin E, and p21(Cip1), associated with decreased expression of p27(Kip1).

p16(INK4a) expression begins early in human colon neoplasia and correlates inversely with markers of cell proliferation

BACKGROUND & AIMS

p16(INK4a) is a cell cycle inhibitor and a major tumor-suppressor protein, but the regulation of p16(INK4a) is poorly understood and the physiologic settings in which it exerts its antiproliferative effects are unknown. A role for p16(INK4a) in intestinal neoplasia is suggested by the observation that the promoter region is methylated in a subset of human colon tumors. We examined the expression of the protein in specimens representing the full spectrum of neoplastic progression in the human colon and determined whether expressing cells showed evidence of cell cycle inhibition.

METHODS

We studied p16(INK4a) expression by immunoprecipitation, immunoblotting, reverse-transcription polymerase chain reaction (RT-PCR), immunohistochemistry, and immunofluorescence in matched normal and neoplastic colonic tissue from 70 patients.

RESULTS

p16(INK4a) expression was very low in normal mucosa, with staining observed in rare epithelial cells at the base of crypts. A distinctly higher expression was found in 4 of 7 aberrant crypt foci, 32 of 36 adenomas, 18 of 28 primary carcinomas, and 5 of 5 metastatic carcinomas. Within each neoplasm p16(INK4a) staining was heterogeneous, with higher expression commonly seen in areas bordering normal tissue. p16(INK4a) staining correlated inversely with that of Ki67, cyclin A, and the retinoblastoma protein, suggesting that cell cycle progression was inhibited.

CONCLUSIONS

These results suggest that p16(INK4a) expression begins in the earliest detectable stages of neoplastic progression in the human colon and exerts a continuous, piecemeal constraint on tumor growth.

Apoptosis and its regulation in flat-type early colorectal carcinoma: comparison with that in polypoid-type early colorectal carcinoma

PURPOSE

The aim of this study was to investigate the relationship among apoptotic cell death, proliferative activity, and the expression of apoptosis-regulating proteins (p53, p21 (WAF1/CIP1), and bax) in flat-type early colorectal carcinoma and to compare these factors with those in polypoid-type early colorectal carcinoma.

METHODS

Formalin-fixed, paraffin-embedded tissues of 11 flat-type early colorectal carcinomas and 17 polypoid-type early carcinomas were studied. The histologic diagnosis was either well-differentiated adenocarcinoma or carcinoma in adenoma, and the depth of invasion was limited to mucosa or submucosa. Apoptotic cells were detected by terminal deoxynucleotide transferase-mediated deoxyuridine triphosphate-biotin nick end-labeling method, and proliferative activity was determined by Ki-67 immunohistochemistry using monoclonal antibody MIB-1. Apoptosis-regulating proteins were determined by immunohistochemistry using antibody DO-7 (p53), Cip1 (p21 (WAF1/CIP1)), and Bax (bax).

RESULTS

There was no significant difference in terminal deoxynucleotide transferase-mediated deoxy-uridine triphosphate-biotin nick end-labeling index between flat-type early colorectal carcinoma and polypoid-type early carcinoma, at 1.9 vs. 1.1, respectively. In flat-type carcinoma terminal deoxynucleotide transferase-mediated deoxyuridine triphosphate-biotin nick end-labeling index in the p53 protein overexpression group was significantly smaller than that in the p53 protein-negative group (P < 0.05). The Ki-67 labeling index/terminal deoxynucleotide transferase-mediated deoxyuridine triphosphate-biotin nick end-labeling index ratio in the p53 protein overexpression group was significantly higher than that in the p53 protein-negative group (P < 0.05). In polypoid-type carcinoma, the terminal deoxynucleotide transferase-mediated deoxyuridine triphosphate-biotin nick end-labeling index and Ki67/terminal deoxynucleotide transferase-mediated deoxyuridine triphosphate-biotin nick end-labeling index ratio showed no significant difference between the p53 protein overexpression group and p53 protein-negative group.

CONCLUSION

p53-dependent apoptosis may contribute to the development of flat-type early colorectal carcinoma. Apoptosis and its regulation in flat-type early colorectal carcinoma may differ from those in polypoid-type carcinoma.

Expression of p27kip1 and p53 in medulloblastoma: relationship with cell proliferation and survival

p27kip1 and p21cip1 are cyclin-dependent kinase (cdk) inhibitors which along with p53 play critical roles in the control of cell cycle progression. Accumulation of p27kip1 in post-mitotic neurons is a major event of neurogenesis. We hypothesized that a dysregulation of the expression of p53 and these cdk inhibitors underlies cellular proliferation in medulloblastomas, and tested this hypothesis by investigating p27kip1, p21cip1, Bcl2 and p53 immunoreactivity in 14 medulloblastoma tumors. We noted an inverse relationship between p27kip1 expression and cellular proliferation (MIB1). Focal islands of neuroblastic or glial differentiation expressed high levels of p27kip1, while the undifferentiated, highly-proliferative population of tumor cells showed no detectable p27kip1 expression, thus suggesting a role for p27kip1 in cell cycle control in medulloblastoma. In addition, there was no detectable p21cip1 expression in any of the medulloblastomas studied. The low level of apoptosis displayed by these tumors was not associated with the expression of Bcl-2. A significant relationship was found between detection of p53 protein and poor survival. Since, p21cip1 and p27kip1 are often co-expressed with other INK4 family of cdk inhibitors during the induction of cellular differentiation and are synergistic in their effect, a deregulation of their coordinate expression may underlie the lack of complete differentiation in medulloblastoma.

Expressions of cell-cycle regulatory gene products in conventional gastric adenomas: possible immunohistochemical markers of malignant transformation

In 54 lesions of gastric adenomas consisting of 31 low-grade adenomas (LGAs) and 23 high-grade adenomas (HGAs), 28 intramucosal carcinomas (IMCs), and 23 carcinomas invading the submucosa (SMCs), the expression of cell-cycle regulatory gene products (p53, p21/waf1, p27/kip1, and Ki-67) was studied using immunohistochemical techniques. Several lesions were also analyzed by the fluorescence in situ hybridization method. The overexpression of p53 was found in no LGAs and in 9% of HGAs, whereas a considerable number of cases showed an overexpression in IMCs (39%) and SMCs (43%). A reduced expression of p21/waf1 was present in only 4% of HGAs. Superficial eccentric positivity was present in all LGAs and 74% of HGAs, whereas it was present in 46% of IMCs and 4% of SMCs. P53-positive and p21/waf1-negative lesions, which were supposed to have a mutated p53 gene, were observed in no LGAs, in 4% of HGAs, in 11% of IMCs, and in 26% of SMCs. The expression of cyclin E was more frequently present in carcinomas than in adenomas. However, no high expression of cyclin E was observed among the adenomas. A reduced expression of p27/kip1 was encountered more frequently in carcinoma than adenoma. By a semiquantitative evaluation comparing adenoma and carcinoma in the same stomach, the increased degrees of both p21/waf1 and cyclin E were highlighted. A chromosome gain was detected among 7% of the adenomas and 85% of the carcinomas. In conclusion, the expressions of p53, p21/waf1, p27/kip1, and cyclin E were considered to be of great value for estimating the dysplastic progression of gastric adenomas. Especially, various aspects of protein expression, including its distribution and semiquantitative evaluation of positive cells, and a combined analysis with several proteins, may thus be useful as possible markers of dysplastic evolution in gastric adenomas.

Prognostic impact of p21/waf1/cip1 in colorectal cancer

In addition to the tumor suppressor gene p53, Cyclin Dependent Kinases (CDK) are well known to influence the cell cycle in normal human tissues and various neoplasias as well. The purpose of our present study was to evaluate the expression of the CDK-inhibitor p21/waf1/cip1 in colorectal cancer with special emphasis on the prognostic impact. Between 1985 and 1991, 294 patients (median age, 65 years) underwent surgical operative therapy for colorectal cancer. Formalin-fixed and paraffin-embedded tumor specimens were investigated. For immunohistochemistry the Catalysed Reporter Deposition (CARD) technique was performed. The survival probability was calculated and possible prognostic risk factors were tested using multivariate analysis. The p21/ waf1/cip1 staining pattern was positive in 197 (67%) specimens and negative in 97 (33%) samples. No significant correlation could been calculated between p21/waf1/cip1 expression and other variables such as age, sex, WHO-Classification, localisation, grading, TNM-classification or UICC-stage. Patients with a positive staining reaction had a significantly better survival (p < 0.0052). Moreover, p21/waf1/cip1 was shown to be an independent prognostic parameter by multivariate analysis (p < 0.022). In contrast with these findings, the p53 tumor status had no impact on survival. P21/ waf1/cip1 appears to be an independent prognostic parameter in colorectal cancer and is associated with a favorable survival. This feature may be related to a cell cycle arrest in the G1 phase induced by p21/waf1/cip1, resulting in lower tumor cell proliferative activity.

Novel polymorphism in p21(waf1/cip1) cyclin dependent kinase inhibitor gene: association with human esophageal cancer

p21(waf1/cip1), an important regulator of the cell cycle, binds to PCNA and acts as a mediator of the growth suppressing and apoptosis promoting functions of p53. We report a hitherto unobserved polymorphism in the carboxy terminal domain (codon 149) of p21(waf1/cip1) gene, the domain encoding the PCNA binding motif. The codon 149 polymorphism (GAT-->GGT) was observed in 42 of 50 (84%) esophageal squamous cell carcinomas (ESCCs) and eight of 50 (16%) normal individuals. The resultant amino acid substitution from aspartate to glycine may have vital implication in PCNA mediated cell cycle regulation by p21(waf1/cip1). The second polymorphism at codon 31, involving a C-->A transversion at nucleotide 168 (AGC-->AGA) changing the amino acid from serine to arginine, was observed in 2/50 (4%) ESCCs at a relatively lower frequency in the Indian population than that reported in the West. No significant association was observed between p21(wap1/cip1) polymorphism at codon 149 and p21(wap1/cip1) protein expression in ESCC in this cohort of patients. Interestingly, the frequency of p21(wap1/cip1) variants (codon 149) in ESCCs (18 of 19 cases) with wild-type p53 was significantly higher than in tumors with p53 mutations, suggesting that this polymorphism affects the p53 pathway and may play an important role in esophageal tumorigenesis. Analysis of p21(waf1/cip1) expression in relation to p53 gene and protein status revealed its induction by p53-dependent as well as independent pathways in esophageal tumorigenesis.