Bcl-2 expression and frequency of apoptosis correlate with morphogenesis of colorectal neoplasia

AIM: To investigate whether the expression of apoptosis and cell proliferation related proteins is related to the macroscopic form of colorectal neoplasia. METHODS: The extent of apoptosis, using the 3' end DNA labelling method, and the immunohistochemical expression of cell proliferation (Ki-67) and apoptosis related proteins (Bcl-2, Bak, and p53) were investigated in 64 colorectal adenomas and 22 early carcinomas extending no further than the upper submucosal region. The specimens were classified into three types of macroscopic form (polypoid, flat, and depressed). RESULTS: The Ki-67 labelling index and the Bak score did not differ significantly among each macroscopic form. In contrast, the apoptotic index and the Bcl-2 score changed significantly according to the macroscopic forms. Compared with polypoid and flat tumours, depressed tumours had a significantly lower apoptotic index (2.84, 2.28, and 1.44, respectively) and a significantly lower Bcl-2 score (3.18, 2.70, and 1.64, respectively). The proliferation/apoptosis ratio was significantly lower in polypoid tumours than in the other two macroscopic forms. The Bcl-2 score became significantly lower as the tumours flattened or took on a depressed form. Immunohistochemical p53 overexpression did not correlate with the macroscopic forms. CONCLUSIONS: These results suggest that differences in both Bcl-2 expression and apoptosis may play an important role in the morphogenesis of colorectal neoplasia.     

Expression of cyclin D1, Ki-67 and PCNA in non-small cell lung cancer: prognostic significance and comparison with p53 and bcl-2

Uncontrolled cell proliferation is the hallmark of malignant tumours. Thus, the proliferative potential of tumour cells is an important prognostic factor. However, evaluation of the prognostic significance of the expression of proteins involved in regulation of cell proliferation remains controversial. In the present study, expression of Ki-67, PCNA and cyclin D1 was estimated in a group of 89 surgically resected non-small cell lung carcinomas using immunohistochemistry. The results were compared with expression of bcl-2 and p53 and with clinicopathological parameters including patients' survival. Ki-67 and PCNA were found to be moderately and highly expressed in 39% and 44% of the tumours, respectively. There was a strong correlation between Ki67 and PCNA expression. Forty five of 88 tumours (51%) showed overexpression of cyclin D1. Surprisingly, cyclin D1 was mainly localized in the cytoplasm and only a small group of tumours (9/88, 10%) showed nuclear staining as well. Bcl-2 and p53 expression was observed in 69% and 30% of the tumours, respectively. All these markers were found to be independent of clinicopathological parameters, except for Ki-67 and bcl-2 expression, which was associated with squamous cell carcinomas. It is concluded that none of the markers that were studied can be used as an independent prognostic factor, whereas the following combinations of markers may have favourable prognostic value: p53 positivity and low Ki-67 expression, p53 positivity and lack of cyclin D1 expression, bcl-2 positivity and low Ki-67 expression, and lack of cyclin D1 expression and low Ki-67 expression.     

Expression of Bcl-2 and p53 correlates with the morphology of gastric neoplasia

The growth of a tumour can be determined by an interplay between cell proliferation and loss. The expression of apoptosis-related proteins (Bcl-2 and p53), cell proliferation (Ki-67), and apoptotic cell death were investigated using immunohistochemistry and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling in gastric neoplams, to evaluate whether they correlate with the morphology of the tumour. The materials included ten cases of gastric adenoma and 40 cases of early gastric carcinoma consisting of differentiated adenocarcinomas (n=20) and undifferentiated carcinomas (n=20). All cases of adenoma and eight cases of differentiated adenocarcinoma were of the elevated type, while 12 differentiated adenocarcinomas and all of the undifferentiated carcinomas were of the depressed type. The diffuse expression of Bcl-2 was observed in all cases of adenoma and seven out of eight (88 per cent) of elevated-type differentiated adenocarcinoma. In contrast, Bcl-2 expression was absent or focal in the depressed type of carcinoma. Overexpression of p53 was found exclusively in the depressed type of carcinoma. Thus, Bcl-2 and p53 expression was associated with tumour morphology. It seemed unlikely that Bcl-2 and p53 expression was involved in the morphogenesis of the gastric tumours through inhibiting apoptotic cell death, since the degree of apoptosis in Bcl-2-positive gastric tumours was rather higher than that in Bcl-2-negative ones and it did not differ significantly between p53-positive and p53-negative tumours. Instead, the diffuse distribution of Bcl-2 correlated with the superficial distribution of Ki-67-positive proliferating cells, and the overexpression of p53 had a tendency to correlate with the diffuse distribution of proliferating cells. These results suggest that diffuse Bcl-2 expression and a superficial distribution of proliferating cells may contribute to the elevated configuration, and that overexpression of p53 and a diffuse distribution of proliferating cells may result in the depressed configuration in the relatively early stages of gastric tumourigenesis. © 1998 John Wiley & Sons, Ltd.     

Imbalance between proliferation and apoptosis in the development of colorectal carcinoma

 To evaluate the relationship between cell proliferation and apoptosis in sporadic colorectal carcinogenesis, immunohistochemistry for proliferation-associated antigen Ki-67 and in situ end labelling for identifying apoptotic bodies were performed on paraffin sections from 59 adenomas and 22 carcinomas. These results were correlated with the expression of the proliferation and apoptosis modulators Bcl-2 and p53. Carcinomas showed increased proliferation and apoptosis compared with adenomas (P<0.0001, P<0.001, respectively). There were positive linear correlations between proliferation and apoptosis in adenomas and carcinomas (P<0.02, P<0.05, respectively). The proliferative rate increased significantly from mild to moderate, and from moderate to severe dysplasia (P<0.002, P<0.001, respectively). Apoptotic rate also increased in this sequence, but the increases did not reach statistical significance (both P>0.05). Expression of Bcl-2 was associated with lower apoptotic rate in adenomas (P<0.025) but not in carcinomas (P>0.25), whereas p53 expression was correlated with higher proliferative rate in both adenomas and carcinomas (P<0.01, P<0.05, respectively). An inverse relationship between Bcl-2 and p53 expression was seen in both adenomas and carcinomas (P<0.05, P<0.005, respectively). These data suggest that the normal balance between proliferation and apoptosis is disturbed in colorectal carcinogenesis, both being increased, but proliferation occurs in excess. Bcl-2 and p53 may each play a role in modulating cell apoptosis or proliferation during the development of colorectal carcinoma. Received: 23 March 1998 / Accepted: 7 July 1998     

Morphogenesis of nonpolypoid colorectal adenomas and early carcinomas assessed by cell proliferation and apoptosis

Nonpolypoid neoplasms, as well as ordinary polypoid tumours, are occasionally found in the colorectum. To clarify whether cell kinetic status affects the macroscopic morphology of colorectal neoplasms, we investigated proliferative indices (PI), apoptotic indices (AI), and the expression of apoptosis-related gene products. We examined 110 colorectal neoplasms comprised of 36 polypoid, 38 flat elevated and 36 depressed tumours. According to WHO’s criteria these tumours consisted of 61 adenomas with low grade dysplasia (LGD), 30 adenomas with high grade dysplasia (HGD) and 19 carcinomas with submucosal invasion. Apoptotic cells were detected by TUNEL staining. Proliferating cells and apoptosis-related gene products were assessed by immunohistochemistry for Ki-67, p53, Bcl-2, and Bax antigens. AI were closely associated with macroscopic morphology in adenomas but not in carcinomas. PI were relatively constant among the three macroscopic types in adenomas and carcinomas. Median AI values of polypoid, flat elevated and depressed tumours were 1.8%, 2.1% and 4.6% for adenomas with LGD, 0.8%, 2.4% and 6.2% for adenomas with HGD and 2.9%, 4.0% and 3.6% for carcinomas, respectively. Overall PI were significantly higher in carcinomas than in adenomas with LGD, whereas AI were not different. Although the incidence of expression was significantly higher in carcinomas for p53 and in adenomas for Bcl-2 than the others, the expression of apoptosis-related gene products (p53, Bcl-2 and Bax) was similar among polypoid, flat elevated and depressed tumours. Macroscopic morphology of colorectal adenomas is determined by the apoptosis not by proliferation, and high apoptosis found in depressed adenomas implies their low net growth. Received: 1 July 1999 / Accepted: 17 January 2000     

Immunohistochemical analysis of bcl-2 and p53 expression in breast carcinomas: their correlation with Ki-67 growth fraction

We examined 59 breast cancers for p53 and bcl-2 protein expression by immunohistochemistry. The results were correlated with Ki-67 immunostaining. p53-negativity was noted in 40 cases and the remaining 19 tumours were p53-positive. Thirty-six tumours showed strong expression of bcl-2 and in 23 no staining for this protein was observed. We found statistically significant reverse correlation between expression of p53 and bcl-2 in majority of carcinomas: 31 cases were bcl-2 positive and p53-negative, and 14 tumours were bcl-2-negative and p53-positive. Six carcinomas showed no nuclear staining for Ki-67 and in the remaining 53 the percent of cancer cells positive for Ki-67 ranged from 1 to 60 (mean: 14.6). In these 53 cases we found that bcl-2-positive tumours were characterized by lower proliferation than bcl-2-negative tumours, the mean value of Ki-67 immunostaining being 10.7% and 23.0%, respectively. p53-negative tumours showed lower proliferation than p53-positive tumours: mean Ki-67 index was 10.2% and 23.9%, respectively.We conclude that immunohistochemically detected p53 and bcl-2 proteins show a significant inverse relationship in majority of breast carcinomas and their expression correlates with tumour proliferation (Ki-67 immunostaining).     

Functional overexpression of wild-type p53 correlates with alveolar cell differentiation in the developing human lung

At 15 weeks after conception (a.c.), the human pulmonary acinus is lined by distal low-columnar and more proximal cuboidal cells that are successive stages in alveolar type II cell differentiation (pseudoglandular period of lung development). From 16 weeks a.c. onward, there are also 'flatter' cells that are intermediate stages in the differentiation of cuboidal type II cells into squamous type I cells (canalicular period). We investigated the role of wild-type p53 protein and the proliferation marker Ki-67 in the differentiation of type II and type I cells in these two periods. Serial sections from fetal lungs (n = 30) were immunoincubated with antibodies against p53 and Ki-67. The presence of prospective type II and type I cells was confirmed using immunohistochemistry for surfactant protein SP-A as a differentiation marker and light and electron microscopy. The p53 and Ki-67 positive nuclei were quantified per alveolar cell phenotype (i.e., low-columnar; cuboidal; flatter). The occurrence of cell apoptosis was studied using propidium iodide (PI) and 4',6'-diamino-2-phenylindol dihydrochloride (DAPI) staining. The combined increase in p53 expression and decrease in Ki-67 expression during alveolar epithelial cell differentiation suggests that wild-type p53 protein plays a role in the differentiation of alveolar type II and type I cells in the human lung, and that this function is mediated through cell cycle arrest. The rare incidence of apoptotic nuclei in alveolar type II cells, together with their absence in alveolar type I cells, supports the view that p53 is involved in the differentiation, rather than the death, of alveolar epithelial cells.     

Extent of apoptosis in ovarian serous carcinoma: relation to mitotic and proliferative indices, p53 expression, and survival.

AIMS: To assess the extent of apoptosis in ovarian serous carcinoma and to examine possible relations between apoptosis, cell proliferation, p53 overexpression, and patient survival. METHODS: Apoptotic and mitotic indices were obtained by examining haematoxylin and eosin stained sections from 30 patients with ovarian serous carcinoma. Apoptosis was also evaluated semiquantitatively by in situ end labelling of fragmented DNA. Expression of p53 and determination of Ki-67 labelling indices were based on immunohistochemical staining. Clinical details were obtained from patients' clinical records. For statistical analysis, Fisher's exact test, parametric (Pearson) linear correlations, and the Kaplan-Meier method were used. RESULTS: The mean apoptotic index was 1.3% (range 0.02-3.9%), the mean mitotic index was 0.4% (range 0.02-1.1%), and the mean Ki-67 labelling index was 16% (range 4-32%). There were significant correlations between the apoptotic and mitotic indices (p < 0.0205) and between the mitotic and Ki-67 labelling indices (p < 0.024). There was a significant correlation between a high apoptotic index and poor prognosis (p < 0.02). p53 was overexpressed in 16 cases but the extent of apoptosis and outcome were both independent of p53 status. CONCLUSIONS: These results suggest that regulation of apoptosis is an integral component of tumour cell kinetics in ovarian serous carcinoma, and that increased apoptosis is indicative of aggressive tumour growth. p53 expression did not correlate with altered apoptosis, but the possibility of an attenuated apoptotic response to subsequent DNA damage by anticancer agents is not excluded.     

p53 N-terminal Ser-15 approximately P and Ser-20 approximately P levels in squamous cell lung cancer after radio/chemotherapy

Functional regulation of p53 protein, a critical regulator of cell cycle and apoptosis, was investigated in fiberoptic bronchoscopy biopsy samples taken from 23 patients suffering from recurrent squamous cell lung cancer by analyzing the expression and phosphorylation status of the p53 at Ser15 and Ser20 before and after treatment with radiotherapy/cisplatin/vinorelbine. Poly(ADP-ribose) levels as a marker of cellular DNA damage, expression of wild-type and mutated p53 protein, and Ki-67 expression as a marker of proliferation was also determined. Median p53 expression increased (61% increase) after therapy. p53 phosphorylated on Ser20 was also increased by approximately 57% in radiotherapy/chemotherapy patients, and these changes correlated with Ki-67 proliferation and with elevated (by 69%; P < 0.01) poly(ADP-ribose) levels. Our data indicate that apart from changes in p53 quantity, post-translational phosphorylation/dephosphorylation-mediated alterations, especially at Ser20 may play a role in p53 stabilization and, therefore, in antiproliferative activity of drugs inducing DNA damage and apoptosis.     

p53 but not erbB-2 expression is associated with rapid tumor proliferation in urinary bladder cancer

Tumor proliferation in bladder cancer is associated with tumor behavior. To assess the association between Ki-67 labeling index (LI), p53, and c-erbB-2 overexpression, formalin-fixed tissue samples of 160 patients with transitional cell carcinoma (TCC) of the urinary bladder were studied by immunohistochemistry. Ki-67 LI was strongly associated with tumor stage (P < .0001), tumor grade (P < .0001), and p53 status (P = .0014) but not with erbB-2 overexpression (P > .2). Ki-67 LI was higher in p53-positive tumors (19%) than in p53-negative tumors (14%) when all stages were compared. Ki-67 LI was independent of p53 expression in pTa tumors (p53-positive, 9%; p53-negative, 11%), showing that p53 overexpression alone is not sufficient to induce rapid tumor cell proliferation in pTa tumors. Ki-67 LI also was independent of p53 expression in pT2 to pT4 tumors (p53-positive, 20%; p53-negative, 23%), indicating that p53 expression is not necessary for rapid tumor cell proliferation in advanced stages. However, there was a striking difference in Ki-67 LI between p53-positive pT1 tumors (22.0% ± 8.8 standard deviation [SD]; n = 20) and p53-negative pT1 tumors (9.7 ± 8.3 SD; n = 22; P = .0001). These results suggest that increased proliferation in p53-positive pT1 tumors is caused by additional alterations that occur during tumor progression.     

POSITIVE CORRELATION BETWEEN APOPTOTIC AND PROLIFERATIVE INDICES IN GASTROINTESTINAL LYMPHOMAS OF MUCOSA-ASSOCIATED LYMPHOID TISSUE (MALT)

To understand the role of deregulation of apoptosis in the pathogenesis of gastrointestinal MALT lymphoma, apoptosis has been quantitatively studied in paraffin sections from 40 cases (19 low grade, 21 high grade). The extent of apoptosis was correlated with histological grade, proliferative activity as measured by immunostaining of Ki67 proliferation antigen, and the expression of bcl-2 and p53 oncoproteins, which are known to participate in the regulation of apoptosis. Both apoptotic and proliferative indices were significantly ( P <0·00001) higher in high-grade than in low-grade tumours. Overall, apoptotic indices were negatively correlated with bcl-2 expression, particularly in low-grade tumours in which both strong bcl-2 expression and low levels of apoptosis were observed. Thus, the slow expansion of low-grade MALT lymphoma may partly result from a prolonged life-span of tumour cells, due to bcl-2-mediated blockage of apoptosis. No difference in apoptotic indices was found between p53-positive and p53-negative cases. Furthermore, correlation analysis revealed a significantly positive association between apoptotic and proliferative indices. This supports the current belief that the mechanisms controlling apoptosis and proliferation are both activated during the cell cycle and whether a cell enters the proliferation cycle or the apoptotic process depends on survival factors.     

Colorectal carcinomas with high microsatellite instability: defining a distinct immunologic and molecular entity with respect to prognostic markers

Molecular analysis of hereditary nonpolyposis colorectal carcinomas (HNPCC) has identified DNA mismatch repair deficiencies with resulting microsatellite instability (MSI) as a pathway of carcinogenesis that appears to be relevant for prognosis, treatment, and possibly prevention. In this study, expression of cell cycle proteins and other known prognostic markers is correlated with the microsatellite status of colorectal cancers (CRC). One hundred consecutive cases from the CRC Registry at Thomas Jefferson University were analyzed for MSI. Immunohistochemistry was performed for the mismatch repair proteins hMLH1 and hMSH2, tumor suppressor p53, apoptosis inhibitor bcl-2, cell cycle proteins p21(WAF1/CIP1), and p27 and the proliferation markers Ki-67 and topoisomerase II. High MSI (MSI-H) is significantly correlated with loss of either hMLH1 or hMSH2, presence of bcl-2, and absence of p53. p21(WAF1/CIP1) is positive in all tumors with MSI-H. Previous findings of a lower proliferation rate were confirmed with a topoisomerase II stain. Microsatellite stable (MSS) tumors generally express both MSH2 and MLH1. Other highly significant differences are positive p53 in 56% of MSS cases and negative bcl-2 in 98% of MSS cases. p27 expression is found in approximately 50% of all CRCs irrespective of the microsatellite status. MSI-H tumors follow the mutator pathway, with loss of expression of one mismatch repair protein, wild-type p53, lower proliferation, and positivity for p21(WAF1/CIP1). MSS tumors follow the suppressor pathway, characterized by p53 overexpression, higher proliferation, and absence of bcl-2 expression; p21(WAF1/CIP1) expression can be variable. These data provide a molecular basis for the clinical observation that patients with HNPCC appear to have a more favorable prognosis. HUM PATHOL 31:1506-1514.     

良恶性脑肿瘤p53蛋白表达与细胞增殖和凋亡的研究

目的探讨脑肿瘤ｐ５３蛋白表达状况对其细胞增殖和凋亡的影响，及这些指标与脑肿瘤组织学类型和恶性程度的关系。方法对１０例对照脑组织和８０例脑肿瘤标本进行原位细胞凋亡及免疫组化标记。结果６９例脑肿瘤（８６．３％）表达ｐ５３蛋白，阳性细胞含量随肿瘤恶性程度升高而增加，对照组全部阴性。各肿瘤组增殖细胞核抗原和Ｋｉ－６７抗原阳性细胞密度均高于对照组，并随肿瘤恶性程度及ｐ５３蛋白表达升高而增加，凋亡细胞密度均低于对照组，并随肿瘤恶性程度及ｐ５３蛋白表达升高而降低。结论提示以上４种指标对评价脑肿瘤生物学行为有参考价值，脑肿瘤ｐ５３蛋白表达和功能异常与其细胞增殖及凋亡失衡有关，可能是原发性和转移性脑肿瘤发生发展的重要因素。     

Coexpression of p53 and c-erbB-2 proteins is associated with histological type, tumour stage, and cell proliferation in malignant salivary gland tumours

The development and progression of cancer are known to be regulated by various oncogenes and tumour suppressor genes. We analysed 63 primary malignant salivary gland tumours for the expression of p53 and c-erbB-2 proteins. Immunohistochemically, 7 of 63 tumours (11%) showed diffuse nuclear staining for p53 protein, and all 7 were also positive for c-erbB-2 protein. The overexpression of p53 protein correlated closely with the overexpression of c-erbB-2 protein (P<0.001). Overexpression of both p53 and c-erbB-2 proteins (coexpression) was found in tumours of certain histological types, such as adenocarcinoma, carcinoma in pleomorphic adenoma, and salivary duct carcinoma. Furthermore, it is noteworthy that coexpression was associated with high-grade carcinoma, advanced tumour stage, and a high Ki-67 labelling index (%) which is a marker of cell proliferation. In adenocarcinoma, we attempted to clarify the relationship between coexpression and histological grade. Coexpression was associated with histological grades showing high mitotic indices and necrotic areas, which reflected high cell-proliferative activity. These results suggest that the accumulation of genetic alterations, such as those involving p53 and c-erbB-2, plays an important part in the progression of malignant salivary gland tumours.     

Clinical significance of Fhit expression in development of colorectal carcinoma of various macroscopic types

It is unclear how expression of the FHIT (fragile histidine triad) gene by the colorectal neoplasm correlates with histogenesis and progression of the disease. We studied the association between expression of Fhit protein and development of colorectal carcinoma (CRC). We also examined relations between Fhit protein expression, macroscopic type, Ki-67 labeling index (LI), and p53 overexpression in carcinoma in situ. We examined 27 colorectal adenomas, 82 carcinomas in situ and 21 invasive CRCs resected endoscopically or surgically. The carcinomas in situ comprised three macroscopic types: polypoid (n=27), superficial (flat elevated, n=27; depressed, n=10) and granulonodular laterally spreading tumor (G-LST, n=23). Fhit, Ki-67, and p53 overexpression were examined immunohistochemically. Levels of Fhit protein were lower in invasive CRC than in adenoma and carcinoma in situ (p<0.01). In carcinoma in situ, reduced Fhit expression was observed in 7 of 22 (31.8%) polypoid types, 13 of 27 (48.1%) superficial flat elevated types, 8 of 10 (80%) superficial depressed types and 7 of 23 (30.4%) G-LST. Frequencies of reduced Fhit expression were significantly higher in the polypoid type and G-LST lesions than in the depressed type (p<0.05). Reduced expression of Fhit protein was related significantly to Ki-67 LI and p53 overexpression in carcinoma in situ (p<0.01). The present findings suggest that reduced expression of Fhit protein is related to development of colorectal neoplasm. Polypoid CRC and G-LST appear to differ from superficial depressed CRC in terms of Fhit expression.     

Proliferation and apoptosis in proliferative lesions of the colon and rectum

 Classically, neoplasia has been considered to be primarily a disturbance in the regulation of proliferation, but it is now clear that programmed cell death is dysregulated as well as proliferation. The genes that are implicated in the regulation of these processes, such as p53, c-myc and bcl-2, are often also altered in neoplasms. We have studied proliferation and programmed cell death in hyperplastic polyps, adenomas, carcinomas in adenomas and adenocarcinomas of the colorectum, using the MIB-1 antibody which recognizes the Ki-67 proliferation related antigen, and an in situ nick-end labelling procedure for histochemical labelling of proliferating and apoptotic cells. In addition, immunohistochemistry was used to study the expression of the p53, c-myc and bcl-2 proteins. The material studied consisted of 12 samples of normal mucosa, 8 hyperplastic polyps, 39 adenomas with different degrees of dysplasia and including 3 that carried a carcinoma, and 10 adenocarcinomas, all formalin fixed and paraffin embedded. The Ki-67 index indicated that proliferation increased progressively in hyperplasia, through different degrees of dysplasia in adenoma, to reach the highest level (Ki-67 index of 50%) in adenocarcinoma. Apoptosis also increased in hyperplastic polyps and in adenomas, but decreased significantly in adenocarcinomas. p53 Labelling was seen in 77% of the carcinomas but in only 3% of the adenomas. Expression of c-myc increased in adenomas and carcinomas. Furthermore, a shift from predominantly nuclear to predominantly cytoplasmic expression was seen in progressive neoplasms. Expression of bcl-2 was increased in an occasional hyperplastic polyp, but was increased markedly in almost all adenomas. Strikingly, in the adenomas with a carcinoma, the carcinoma showed weaker bcl-2 expression than the adenoma. In 20% of the carcinomas some bcl-2 staining was seen but this was less extensive than in the adenomas. Our findings indicate that in the progression from adenoma to carcinoma both increased proliferation and decreased apoptosis occur. This is paralleled by an increased expression of p53 and an increased and predominantly cytoplasmic expression of c-myc, but a decreased expression of bcl-2. This decreased bcl-2 expression does not lead to an increase in apoptotic activity. Received: 16 January 1997 / Accepted: 10 March 1997     

Post-thymic T cell lymphomas frequently overexpress p53 protein but infrequently exhibit p53 gene mutations.

We recently demonstrated that only one of 36 T-cell neoplasms contained p53 gene mutations. Although p53 gene mutations are known to result in overexpression of the p53 gene product, we also recently discovered that p53 protein overexpression does not correlate with p53 gene mutations, but does correlate with proliferation (r = 0.92), in anaplastic large cell lymphoma. In view of these findings, we investigated 34 non-human T-cell lymphotropic virus type I (HTLV-I) related postthymic T-cell lymphomas immunohistochemically for p53 protein, using monoclonal antibody 1801, and for proliferation, using monoclonal antibody Ki-67, and quantitated the results with the CAS-200 computerized image analysis system. We evaluated the presence of mutations in conserved exons 5 to 9 of the p53 gene using single-strand conformation polymorphism analysis and DNA sequencing. p53 mutations were detected in three of 34 cases, including two that contained deletions. p53 protein overexpression was detected in 17 of 34 cases, including the three mutated cases, with reactivities ranging from 10% to 48%. However, many cases in which a structural alteration could not be detected demonstrated levels of p53 protein expression comparable to those cases that were mutated. Correlation of p53 protein expression and proliferation, as assessed by Ki-67 expression, in this group of lymphomas was poor (r = 0.34). Whether alternative mechanisms of p53 protein inactivation are causing phenotypic overexpression of the p53 protein in these malignant lymphomas is unknown, although preliminary studies do not support a major role for such mechanisms. Therefore, the etiology and the significance of p53 protein overexpression in the cases that lack a demonstrable mutation is unclear. Nevertheless, as in anaplastic large cell lymphoma, overexpression of the p53 gene product is not a reliable predictor of the presence of mutations in conserved portions of the p53 gene in non-HTLV-I associated post-thymic T-cell lymphoma.     

The relationship between the gene mutation of p53 and the protein expression of p53 and Ki-67 in non-Hodgkin's lymphomas

The relationship between the mutation of the p53 gene and the expression of the p53 protein and the Ki-67 antigen has been investigated in 115 cases with non-Hodgkin's lymphoma, using the immunohistochemical double staining technique, single-strand conformational polymorphism and DNA sequencing methods. Eighteen cases showed more than 10% of p53+ cells and the others showed a few p53+ cells presented sporadically. Alterations in the p53 gene were detected in six cases with B cell type, consisting of five cases with point mutation and one case with point mutation and 15 base pairs deletion. These six cases showed a high percentage of p53+ cells and five cases revealed that the percentage of p53+ cells was higher than that of Ki-67+ cells (p53+ cells > Ki-67+ cells). Excluding the six cases with mutation of the p53 gene, all cases revealed that the percentage of p53+ cells was less than that of Ki-67+ cells (p53+ cells < Ki-67+ cells). Moreover, there was a positive correlation between expression of the p53 protein and of the Ki-67 antigen in histologic types of B cell lymphomas and of T cell lymphomas, respectively, except in small non-cleaved (Burkitt's) and lymphoblastic types. Therefore, sporadic cases showing p53+ cells > Ki-67+ cells revealed alteration of the p53 gene, and expressed abnormal p53 protein (mutant form). Most cases showing p53+ cells < Ki-67+ cells expressed normal p53 protein (wild type), and may reflect the rapid proliferation rate.     

Apoptosis in operated small cell lung carcinoma is inversely related to tumour necrosis and p53 immunoreactivity

The present study was undertaken to analyse the extent of apoptosis in operated small cell lung carcinoma (SCLC) by using in situ labelling of the oligonucleosomal DNA fragments by terminal transferase. The extent of apoptosis was compared with the cell proliferation activity, as determined by Ki-67 immunohistochemistry; with the volume density of necrosis (per cent), as determined by the morphometric point counting method; and with the occurrence of immunohistochemically detectable p53 and bcl-2 proteins. By in situ labelling, remarkably high apoptotic indices (from 0·08 to 8·10 per cent) were seen in SCLC. A high percentage of SCLSs also showed an exceptionally high proliferation activity. Aberrant accumulation of p53 protein was seen in 37·5 per cent and bcl-2 overexpression in 50 per cent of SCLCs. Necrosis was seen in 82·5 per cent of SCLCs. The extent of apoptosis was inversely related to the extent of tumour necrosis (P=0·05) and to p53 protein accumulation (P=0·008). A positive association was found between the extent of apoptosis and bcl-2 immunoreactivity (P=0·02). The apoptotic indices (per cent) correlated with the age (P<0·05) and total smoking time of the patients (P=0·06). © 1997 John Wiley & Sons, Ltd.