Correlation of p53 protein expression with apoptotic incidence in colorectal neoplasia

Hepatocyte morphology and kinetics after portal vein embolization

BACKGROUND

Macroscopic volume changes after portal vein embolization (PVE) can be assessed accurately by computed tomography, but histological changes remain poorly understood. The aim of this study was to clarify hepatocyte morphology and kinetics after PVE.

METHODS

The resected livers from 25 patients who underwent extended hepatectomy after PVE and five normal livers were examined using hepatocyte paraffin 1 staining for histomorphometric analysis of hepatocytes. Cell kinetics were determined by Ki-67 staining and terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick-end labelling assay. Kupffer cells were examined by CD68 immunostaining.

RESULTS

The number of hepatocytes was similar in the embolized lobe, non-embolized lobe and normal liver, but hepatocyte volume was greater in the non-embolized lobe than in the embolized lobe (P = 0.017). The Ki-67 labelling index was higher in the non-embolized lobe (P < 0.001) whereas the apoptotic index was higher in the embolized lobe (P < 0.001). There were more Kupffer cells per unit area in the embolized lobe (P < 0.001).

CONCLUSION

Hepatocyte hypertrophy and replication leads to volume enlargement of the non-embolized hepatic lobe, whereas hepatocyte atrophy and apoptosis causes a decrease in volume of the embolized lobe.

Risk of recurrence after surgical resection of small-sized invasive lung adenocarcinoma

OBJECTIVE

It has been reported that small-sized invasive lung adenocarcinomas, i.e., those classified as type C through type F according to Noguchi's classification, may also recur even after complete resection. We evaluated the prognostic value of molecular biologic markers (apoptosis, Ki-67, p53, epidermal growth factor) and clinicopathological factors in patients with small-sized invasive lung adenocarcinomas.

METHODS

The clinical records of all patients who had had a peripheral adenocarcinoma surgically resected between 1996 and 2002, and histologically diagnosed as type C through type F according to Noguchi's classification were retrospectively reviewed. The apoptotic index (AI) was determined by the triphosphate biotin nick end-labeling method and the expression of Ki-67, aberrant p53 protein and epidermal growth factor receptor was determined by immunohistochemical staining.

RESULTS

Data from 28 patients who had been followed up for a mean period of 41.8 months (range: 16 to 89 months) were evaluated. During the follow-up period, recurrence was seen in 6 patients. The log-rank test showed that AI was a significant predictor of cancer recurrence. The 5-year disease-free survival rate of the 10 patients in the high AI group (AI > 0.3%) was 100%; while that of the 18 patients in the low AI group (AI < or = 0.3%) was 50.5% (p = 0.036). None of the other molecular biologic markers or clinicopathological factors were found to be a significant predictor of cancer recurrence.

CONCLUSION

Peripheral small-sized invasive lung adenocarcinomas with a low AI carry an increased risk of distant metastases, indicating that adjuvant chemotherapy after complete resection might be needed.

Bidirectional gastric differentiation in cellular mucin phenotype (foveolar and pyloric) in serrated adenoma and hyperplastic polyp of the colorectum

This study examined whether gastric pyloric gland-type mucin is expressed in serrated adenoma (SA) and in hyperplastic polyp (HP) of the colorectum, and whether cellular position-based gastric differentiation is observed in these lesions as previously hypothesized. Immunostaining was performed for MUC6 and alpha-linked GlcNAc residue (pyloric gland-type mucin markers), human gastric mucin (HGM; foveolar-type mucin marker) and Ki-67 (proliferating cell marker) for 31 SA, 22 HP, 21 traditional tubular adenoma (TA) and 20 hyperplastic nodule (HN). MUC6 showed varying expression in SA, 22/31 (71.0%); HP, 15/22 (68.2%); TA, 2/21 (9.5%); and HN, 0/20 (0%) with significantly higher frequencies in SA and HP compared to those in TA and HN. The alpha-linked GlcNAc residue was found only in SA (3/31, 9.7%) and in HP (2/22, 9.1%). In SA and HP, HGM was typically expressed in the entire crypt length, but some reduction in expression was shown in the basal crypt portion below the proliferative zone. MUC6 and alpha-linked GlcNAc residues were expressed in the basal crypt portion below or below and including proliferative zone. These data demonstrate that SA and HP show bidirectional gastric (foveolar and pyloric gland) differentiation with respect to mucin cellular phenotype and the potential for cellular position-based differentiation, which mimics the gastric antral mucosa.

p150 overexpression in gastric carcinoma: the association with p53, apoptosis and cell proliferation

To clarify the significance of p150 expression, 102 gastric carcinomas were immunohistochemically investigated and 14 fresh samples of the cancer were analyzed with the immunoblot method. Tumor cell apoptosis was assessed by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-digoxigenin nick end labeling (TUNEL). Both Ki-67 antigen and p53 expression were analyzed immunohistochemically. Eighty-six out of 102 (85%) gastric cancers stained positively for p150. All 14 tumors analyzed by Western blotting overexpressed p150. Statistical analysis revealed a close association between p150 overexpression and the clinicopathologic parameters of gastric cancer. All well-differentiated cancers showed high p150 expression (p < 0.005). Furthermore, high p150 expression was more frequently seen in tumors at early invasive stages (p < 0.005), in tumors without metastases (both local and distant, p < 0.005) and in early TNM stages (p < 0.005) in general. As we have found for cervix and esophagus carcinoma, when tumors progress to high malignancy and metastasis, p150 begins to regress and then breaks down. A good correlation of p150 expression, but not p53 expression, with tumor cell apoptosis could be demonstrated (p < 0.01). The Ki-67 labeling index, i.e., the index for a proliferative marker, showed no correlation with either p150 or p53 expression. The results suggest that p150 may be a new early tumor marker for gastric carcinoma similar to that for esophagus and cervix carcinoma.

Morphologically distinct patterns of apoptosis correlate with size and high-grade dysplasia in colonic adenomas

AIMS

To examine the relationship of morphological patterns of apoptosis in colonic adenomas to standard pathological variables.

METHODS AND RESULTS

Apoptosis patterns were evaluated in 184 consecutive colonic adenomas and 14 adenocarcinomas, using haematoxylin and eosin sections. Apoptosis identification was selectively validated by electron microscopy. There were three patterns of apoptosis: (i) confluent basal apoptosis; (ii) crypt lumen apoptosis, both assessed semiquantitatively; and (iii) scattered apoptosis (not quantified). Adenoma site, size, type, mitoses, and grade of dysplasia were also assessed. MIB-1 immunostaining was performed in 20 cases. In 142 adenomas (77%) confluent basal apoptosis (n = 124) and/or crypt lumen apoptosis (n = 69) were identified; 42 (23%) had scattered apoptosis only. Significant correlations were: (i) extensive confluent basal apoptosis with small adenomas < or =5 mm (P < 0.0001); (ii) crypt lumen apoptosis with large adenomas >5 mm (P < 0.0001) and (iii) with high-grade dysplasia (P < 0.0003); and (iv) coexistence of both patterns (n = 51) with large adenomas >5 mm (P < 0.0001). Neither apoptosis pattern correlated with other variables. Adenocarcinomas had minimal confluent basal apoptosis (5/14), conspicuous crypt lumen apoptosis (14/14), intraglandular coagulative necrosis, and scattered apoptotic tumour cells.

CONCLUSIONS

Confluent basal apoptosis is maximal early in colonic tumorigenesis. The 'switch' to a predominant crypt lumen apoptosis pattern suggests that a different apoptosis induction mechanism might be associated with the transition to adenocarcinoma.

Proliferation kinetics and apoptosis of serrated adenoma of the colorectum

To elucidate the proliferation kinetics and cell loss by apoptosis of serrated adenoma (SA) of the colorectum, we performed Ki-67 immunohistochemistry and the terminal deoxynucleotidyl transferase (TdT)-mediated biotinylated deoxyuridine-triphosphate nick-end labeling (TUNEL) method for 24 SA, and compared the results to those of normal colonic mucosa (n = 15), hyperplastic polyp (HP) (n = 18) and traditional tubular adenoma (TA) (n = 55). The growth fraction (Ki-67 labeling index) of SA was 18.8%, which was significantly lower than those of TA (40.1%) and HP (23.8%), while the apoptotic index of SA (0.14%) was significantly lower than that of TA (1.17%). The proliferative compartment in SA was distributed either basally (47%, 60/117 crypts), or in the intermediate portion (51.3%, 55/117 crypts), and there was no superficial translocation of the proliferative compartment, which was seen in 81.2% (361/445 crypts) of TA crypts. These results indicate that SA is a tumor with low proliferative activity and its growth would be maintained by a low extent of cell loss by apoptosis. The results also indicate the neoplastic process in SA is characterized by the disorder of cell migration, maturation and exfoliation similar to HP, and its epithelial cell maturation and migration occasionally occur bidirectionally, toward the surface and to the bottom of the crypt.

Changes in apoptosis during the development of colorectal cancer: a systematic review of the literature

The development of colorectal cancer is characterised by an accumulation of molecular genetic alterations causing disorders in cell growth, differentiation and apoptosis. Although changes in apoptosis with colorectal cancer development have been studied extensively, a clear consensus of opinion has not yet emerged. In this review, the literature about changes in the frequency and distribution of apoptosis in tissue sections of normal and neoplastic colorectal tissues was reviewed systematically. Using a PUBMED search, 53 relevant articles were identified. Data from these studies are discussed with respect to the following aspects: methods used to detect apoptotic cell death; frequency and locoregional distribution of apoptosis in normal mucosa, adenomas and carcinomas; the correlation between levels of apoptosis and proliferation and the prognostic significance of the degree of apoptosis in colorectal cancer. Possible underlying mechanisms of dysregulation of apoptosis are discussed briefly. Finally, possible therapeutic implications of knowledge of the molecular regulation of apoptosis are discussed and potential options for further research are suggested.

Apoptotic tumor-cell death in response to cell proliferation is influenced by p53 status in resected non-small cell lung cancer

To evaluate the influence of p53 status on postoperative survival and incidence of apoptosis (apoptotic index, AI) in non-small cell lung cancer (NSCLC), a total of 185 pathologic stage I patients were retrospectively analyzed. It was demonstrated by univariate and multivariate analyses that aberrant expression of p53 was a significant factor to predict a poor prognosis, which was caused by a significantly higher proliferative index (PI) in tumor with aberrant expression of p53 (52.7%) than that in tumor without aberrant expression of p53 (37.9%, P < 0.001). In addition, for tumor without aberrant expression of p53, mean AIs of the lowest-, the lower-, the higher-, and the highest-PI groups were 12.6, 12.9, 31.3, and 35.1, respectively, showing that incidence of apoptosis was markedly increased in response to cell proliferation (P = 0.002). In contrast, for tumor with aberrant expression of p53, no increase in incidence of apoptosis in response to cell proliferation was documented. These results clearly demonstrated that active cell proliferation and reduced apoptotic cell death in response to cell proliferation resulted in the poor postoperative prognosis in tumor with aberrant expression of p53.

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.

The Incidence of Apoptosis During Colorectal Tumorigenesis

Epithelial homeostasis in colorectal tumorigenesis is dependent not only on the rate of cell production but also on the rate of apoptosis, a genetically programmed process of autonomous cell death. Ideally, an analysis of cell kinetics should be carried out for both cell proliferation and death. We investigated the incidence of apoptosis in 35 colorectal neoplasms (15 adenomas and 20 carcinomas) using the DNA nick end labeling method (TUNEL). The expression of Ki-67 as a marker of proliferating activity and some kinds of oncogene products were analyzed immunohistochemically. When the TUNEL labeling index (TI) and the Ki-67 labeling index (KI) were determined, TI was found to be significantly higher in adenomas with high-grade dysplasia (TI: 2.5%) than in adenomas with low-grade dysplasia (TI: 0.6%) or carcinomas (TI: 1.4%). In contrast, KI increased with the progression of colorectal tumorigenesis. Moreover, TI of the carcinomas was significantly higher in c-Myc-positive cases than in c-Myc-negative cases (p<0.05). The results indicate that apoptosis plays an important role in the early stage of the adenoma-carcinoma sequence, permitting us to speculate that the increased tumor cell proliferation is negated by increased apoptosis at the stage of adenoma with high-grade dysplasia (or intramucosal carcinoma), while cell proliferation overwhelms cell death at the stage of invasive carcinoma. Int J Surg Pathol 8(2):123-132, 2000

Apoptosis in parathyroid hyperplasia of patients with primary or secondary uremic hyperparathyroidism

BACKGROUND

Chronic oversecretion of parathyroid hormone (PTH) is associated with parathyroid hyperplasia, reflecting a disturbed balance between cell proliferation and apoptosis. This study addressed the unsolved issue of apoptosis in hyperparathyroidism.

METHODS

Parathyroid glands from 19 patients with primary (1 degrees ) and 11 patients with secondary (2 degrees ) uremic hyperparathyroidism, as well as 13 normal parathyroid glands, were examined. Apoptosis was evaluated by terminal deoxynucleotidyl transferase (Tdt)-mediated dUTP nick end-labeling assay (TUNEL). Because the apoptotic process is regulated by several oncoproteins, the expression of Bcl-2 and Bax was analyzed by immunohistochemistry.

RESULTS

The numbers of apoptotic cells in 1 degrees parathyroid adenoma (0.99 +/- 0.03 per 1000 cells, mean +/- SE, P < 0.009) and 2 degrees parathyroid hyperplasia (1.20 +/- 0.54 per 1000 cells, P < 0.005) were significantly higher than in normal parathyroid tissue (0.13 +/- 0. 06 per 1000 cells). Light microscopy examination of hyperplastic parathyroid tissue from a uremic patient showed the presence of nuclei with dense chromatin characteristic of apoptosis. Bcl-2 staining was strong in normal tissues but weak or negative in several sections of 1 degrees and 2 degrees hyperparathyroid tissues, mostly in nodular areas. Bax staining was homogeneous in normal tissue but patchy in several hyperplastic tissues.

CONCLUSION

These results suggest that hyperparathyroidism is associated with a compensatory increase in apoptosis, possibly favored by a diminished Bcl-2/Bax ratio. This renders highly improbable the hypothesis that parathyroid hyperplasia is due to a decreased rate of apoptosis.

Expression of apoptosis and its related protein in astrocytic tumors

The relationship between malignant potential and apoptosis in astrocytic tumors has not been clearly defined, and further classification of astrocytic tumors is necessary. To elucidate the relationship between the histopathological grade of astrocytic tumors and apoptosis, we studied 25 cases of astrocytic tumors, comprising 10 cases of glioblastoma (GB), 7 cases of anaplastic astrocytoma (AA), and 8 cases of astrocytoma (AC). We detected apoptosis using the TdT-mediated dUTP-biotin nick-end labeling (TUNEL) method. We studied immunohistochemical expression of bcl-2 protein and p53 protein, which are apoptosis-related factors, and cell proliferative activity using Ki-67 antibody. No significant change was noted between apoptotic index and the histological grade of the tumors. In GB, apoptotic cell-rich foci were present at the pseudopalisading necrosis. No correlation between histopathological grades and expression of either p53 or bcl-2 was observed. In GB, however, poor distribution of bcl-2 was found in the areas of pseudopalisade formation. bcl-2 is one of the regulatory factors in the cell cycle and inhibits apoptosis. Expression of apoptosis had no correlation with histopathological grade. However, in GB, the distribution of apoptotic cells showed a correlation with bcl-2-poor foci. It was thought that apoptosis was one of the regulatory factors in the formation of pseudopalisading necrosis in GB.

Depressed adenoma of the duodenum in patients with familial adenomatous polyposis: endoscopic and immunohistochemical features

BACKGROUND

Depressed neoplastic lesions of the colorectum have been specified in patients with familial adenomatous polyposis (FAP). The aim of this study was to characterize endoscopic, histologic, and immunohistochemical features of depressed adenoma of the duodenum in patients with FAP.

METHODS

Duodenoscopy was performed on 25 patients with FAP, and the neoplastic nonampullary lesions were classified as polypoid or depressed adenomas. The grade of dysplasia, the proliferative activity determined by Ki-67 labeling index (LI), and the grade of p53 expression were compared between polypoid and depressed neoplasia.

RESULTS

Ten subjects had depressed nonampullary adenoma, whereas polypoid adenoma was found in the remaining 15 subjects. Moderate dysplasia was more frequent in depressed adenoma than in polypoid adenoma (70% vs. 27%, P = 0.04). Whereas p53 expression was not different between the two adenoma groups, the LI was significantly higher in depressed adenoma than in polypoid adenoma (59.7 +/- 9.5 vs. 47.5 +/- 10.7, P < 0.01).

CONCLUSIONS

Depressed adenoma of the duodenum is a distinctive phenotype of duodenal neoplasm in patients with FAP. The high proliferative activity of depressed adenoma suggests that there may be a need to survey FAP patients with such lesions intensively.

Prognostic significance of apoptotic index in completely resected non-small-cell lung cancer

PURPOSE

To evaluate the significance of apoptotic index (AI) as a prognostic factor after surgery for non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

A total of 236 patients who underwent surgery for previously untreated pathologic stage I to IIIa NSCLC between 1985 and 1990 were reviewed. AI was defined as the number of apoptotic cells, detected by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end-labeling, per 1,000 tumor cells. Proliferative index (PI) and aberrant p53 expression were also evaluated immunohistochemically.

RESULTS

The 5-year survival rate for the lowest-AI group (AI < 5.0) was 74.7%; those for the lower-AI group (5.0 < or = AI < 11.0) and the higher-AI group (11.0 < or = AI < 25.0) were 51.6% and 57.8%, respectively. These survival rates were significantly lower than that of the lowest-AI group (P =.021 and P =.043, respectively). The highest-AI group (25.0 < or = AI), however, showed the most favorable prognosis, with a 5-year survival rate of 83.2%. Multivariate analysis confirmed that a moderate AI (5.0 < or = AI < 11.0 or 11.0 < or = AI < 25.0) was a significant factor to predict poor prognosis. The PIs for the lowest-, the lower-, the higher-, and the highest-AI groups were 32.3%, 48.0%, 54.3%, and 50.7%, respectively. The lowest-AI group showed a favorable prognosis because of its low PI, whereas the lower- and the higher-AI groups had a poor prognosis caused by increased cancer-cell proliferation. The highest-AI group showed the most favorable prognosis because apoptotic cell death overcame cell proliferation. No significant correlation was observed between AI and aberrant p53 expression.

CONCLUSION

AI proved to be an independent prognostic factor in NSCLC.

Growth dysregulation and p53 accumulation in human primary colorectal cancer

p53 accumulation is common in colorectal cancer, but effects on growth homeostasis are unclear. In this study, DNA content, cell cycle phase fractions and DNA strand-breaks consistent with apoptosis were assessed by flow cytometry in 42 fresh primary colorectal tumours and matched normal mucosa. p53 accumulation was assessed in 37 fixed tumour sections, by immunohistochemistry. In normal mucosa, 10.3 +/- 6.6% (mean +/- s.d.) cells were in DNA synthesis phase while 28.7 +/- 17.9% showed apoptosis. A relationship suggestive of growth homeostasis, was observed between these parameters (r = 0.8; P < 0.05). In cancers, a greater number of cells were in DNA synthesis phase (15.6 +/- 12.9% tumour vs mucosa 10.3 +/- 6.6%; P < 0.02) while fewer showed apoptosis than normal mucosa (18.5 +/- 17.0% tumour vs mucosa 28.7 +/- 17.9%; P < 0.01). DNA synthesis and apoptosis fractions were unrelated in cancers, suggesting growth dysequilibrium. p53 accumulation was detected in 59% (22/37) tumours and was associated with reduced apoptosis compared to p53-negative tumours or mucosa (14.8 +/- 15% p53 accumulation vs 26.3 +/- 18% p53-negative; P < 0.05; vs 28.7 +/- 17.9% mucosa; P < 0.05). p53 accumulation was unrelated to DNA synthesis phase fractions. p53 accumulation is accompanied by reduced apoptosis which may accentuate growth dysequilibrium in colorectal cancer.

[The relationship between p53 protein and c-erb B-2 expression and apoptosis in colorectal cancer]

In order to elucidate the relationship between tumor growth and various kinds of gene expression and the occurrence of apoptosis in the front portion of neoplastic invasion, 57 advanced colorectal cancers were studied by immunohistochemical staining of p53, c-erb B-2, the TUNEL method and electron microscopy. Light microscopically, the columnar epithelial cells of adenocarcinoma frequently showed a decrease in high and a fall off into the lumen in tumor invasive forefront. Immunohistochemically the positive rate of p53 and c-erb B-2 in tumors with high vascular invasion were higher (p < 0.05) than in those with low vascular invasion. There was a close correlation between the vascular or lymphatic invasion and positive immunoreactivity of p53 and c-erb B-2. The apoptosis index was demonstrated to be related to vessel invasion, over expression of p53 and inflammatory cell infiltration around the front portion of the tumor invasion. These results suggested that p53. c-erb B-2 and the apoptosis index should be evaluated in conjunction with the prognostic factors in colorectal cancer. The infiltrative inflammatory cells may induce apoptosis of the tumor cells.

Deregulation of apoptosis in colorectal carcinoma: theoretical and therapeutic implications

Apoptosis, or programmed cell death, maintains the structure of the colonic crypts by providing a balance to the rate of cell proliferation. Colorectal carcinoma arises partly from a disruption in this balance in the favour of uncontrolled growth. Until recently, most research into colon cancer has focused on the molecular regulators of cell-cycle progression and proliferation, but it is now evident that apoptosis is also defective. A failure of cells to die in response to premalignant damage may allow the progression of the disease and maintain the resistance of cancer cells to cytotoxic therapy. This review outlines the importance of apoptosis in the normal colon and presents recent studies that demonstrate that induction of apoptosis is defective in colonic tumours. When the molecular regulation of apoptosis is better understood, this knowledge may lead to the earlier detection of patients at greater risk of developing colorectal carcinoma, and also to the development of more effective therapies.

Growth patterns in various macroscopic types of noninvasive intramucosal colorectal carcinoma with special reference to apoptosis and cell proliferation

PURPOSE

Apoptotic cell death and cell proliferation play important roles in the histogenesis and development of colorectal carcinoma. The aim of this study was to examine the relationship between apoptosis and cell proliferation in various macroscopic types of intramucosal colorectal carcinoma in relation to the expression of p53 and bcl-2.

METHODS

One hundred forty cases with endoscopically or surgically resected intramucosal colorectal carcinoma were studied. There were 57 cases of polypoid-type carcinomas, 55 cases of superficial-type carcinomas, and 28 cases of granular-type, laterally spreading tumors. Polypoid-type carcinomas were pedunculated, subpedunculated, or sessile polyps. Superficial-type carcinomas were flat lesions with a smooth, even surface. Granular-type, laterally spreading tumors were superficially spreading lesions with aggregates of nodules and a granular surface. Apoptotic cells were identified by the in situ DNA nick end labeling method. Ki-67, p53, and bcl-2 expression were examined immunohistochemically.

RESULTS

The superficial-type carcinoma apoptotic index (30.9 percent) was significantly lower than that of polypoid-type carcinoma (54.4 percent) and granular-type, laterally spreading tumor (60.7 percent). The superficial-type carcinoma proliferative index (67.3 percent) was significantly higher than that of polypoid-type carcinoma (42.1 percent) and granular-type, laterally spreading tumor (28.6 percent). In superficial-type carcinomas the proliferative index in p53-positive carcinomas was significantly higher, and the apoptotic index was higher in carcinomas with a lower proliferative index. There was no significant difference in apoptotic index, proliferative index, or p53 protein overexpression between de novo carcinomas and those that had arisen in precursor adenomas.

CONCLUSIONS

The pattern of cell death and proliferation may vary with different macroscopic types of intramucosal colorectal carcinoma. Superficial-type colorectal carcinomas especially demonstrate diminished apoptosis and increased cell proliferation. This may be useful in understanding their biologic behavior.

Giant cell tumor of bone: a clinicopathologic study of prognostic factors

Forty-seven cases of giant cell tumor of bone were clinicopathologically reviewed to determine any useful prognostic factors. Disease recurred in 11 cases. Eight of these cases had initially been treated with intracapsular piecemeal excision and three cases had been treated with wide excision. Nine of the 11 cases were classified as Grade III, two cases as Grade II, and one case as Grade II + fracture according to Campanacci's radiographic grading system. Intracapsularly excised cases had a high recurrence rate (47.1%). Metastasis to the lung occurred in three cases, each of which had been classified as Grade III. Although the radiographic Grade did not correlate with the rate of lung metastasis or recurrence, cases that metastasized to the lung or recurred tended to be radiographically aggressive. Disease recurred in eight of 24 Grade III cases; but in only two of 12 Grade II cases, in one of five Grade II + fracture cases, and none of six Grade I cases. p53 was expressed by mononuclear stromal cells in six cases. Disease recurred in four and lung metastasis occurred in three of these cases. p53 Expression correlated with rates of lung metastasis and recurrence. It was concluded that cases in which p53 is expressed have a high potential for lung metastasis and recurrence.

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.

Molecular biology of colorectal cancer

Colorectal cancer is a significant cause of morbidity and mortality in Western populations. This cancer develops as a result of the pathologic transformation of normal colonic epithelium to an adenomatous polyp and ultimately an invasive cancer. The multistep progression requires years and possibly decades and is accompanied by a number of recently characterized genetic alterations. Mutations in two classes of genes, tumor-suppressor genes and proto-oncogenes, are thought to impart a proliferative advantage to cells and contribute to development of the malignant phenotype. Inactivating mutations of both copies (alleles) of the adenomatous polyposis coli (APC) gene--a tumor-suppressor gene on chromosome 5q--mark one of the earliest events in colorectal carcinogenesis. Germline mutation of the APC gene and subsequent somatic mutation of the second APC allele cause the inherited familial adenomatous polyposis syndrome. This syndrome is characterized by the presence of hundreds to thousands of colonic adenomatous polyps. If these polyps are left untreated, colorectal cancer develops. Mutation leading to dysregulation of the K-ras protooncogene is also thought to be an early event in colon cancer formation. Conversely, loss of heterozygosity on the long arm of chromosome 18 (18q) occurs later in the sequence of development from adenoma to carcinoma, and this mutation may predict poor prognosis. Loss of the 18q region is thought to contribute to inactivation of the DCC tumor-suppressor gene. More recent evidence suggests that other tumor-suppressor genes--DPC4 and MADR2 of the transforming growth factor beta (TGF-beta) pathway--also may be inactivated by allelic loss on chromosome 18q. In addition, mutation of the tumor-suppressor gene p53 on chromosome 17p appears to be a late phenomenon in colorectal carcinogenesis. This mutation may allow the growing tumor with multiple genetic alterations to evade cell cycle arrest and apoptosis. Neoplastic progression is probably accompanied by additional, undiscovered genetic events, which are indicated by allelic loss on chromosomes 1q, 4p, 6p, 8p, 9q, and 22q in 25% to 50% of colorectal cancers. Recently, a third class of genes, DNA repair genes, has been implicated in tumorigenesis of colorectal cancer. Study findings suggest that DNA mismatch repair deficiency, due to germline mutation of the hMSH2, hMLH1, hPMS1, or hPMS2 genes, contributes to development of hereditary nonpolyposis colorectal cancer. The majority of tumors in patients with this disease and 10% to 15% of sporadic colon cancers display microsatellite instability, also know as the replication error positive (RER+) phenotype. This molecular marker of DNA mismatch repair deficiency may predict improved patient survival. Mismatch repair deficiency is thought to lead to mutation and inactivation of the genes for type II TGF-beta receptor and insulin-like growth-factor II receptor. Individuals from families at high risk for colorectal cancer (hereditary nonpolyposis colorectal cancer or familial adenomatous polyposis) should be offered genetic counseling, predictive molecular testing, and when indicated, endoscopic surveillance at appropriate intervals. Recent studies have examined colorectal carcinogenesis in the light of other genetic processes. Telomerase activity is present in almost all cancers, including colorectal cancer, but rarely in benign lesions such as adenomatous polyps or normal tissues. Furthermore, genetic alterations that allow transformed colorectal epithelial cells to escape cell cycle arrest or apoptosis also have been recognized. In addition, hypomethylation or hypermethylation of DNA sequences may alter gene expression without nucleic acid mutation.

Differential expression of apoptosis, Bcl-x and c-Myc in normal and malignant lymphoid tissues

Bcl-x and c-Myc have an important role for the immune response by regulating the programmed cell death (apoptosis) of lymphocytes. Dysfunction of these selection processes can lead to the development of malignant lymphoma. The present study aimed at defining the differential expression of apoptosis, Bcl-x and c-Myc in normal and in malignant lymphoid tissues. Follicular centre lymphoma (FCL-F) and mantle cell lymphoma (MCL) contained the lowest apoptotic indices (AIs), whereas Burkitt's lymphoma (BL) had the highest AIs. The AIs correlated significantly with the growth rates of the tumours and with the extent of Bcl-x expression. Bcl-x was expressed in almost all BL cells, but in few tumour cells in FCL-F and in MCL. c-Myc, in contrast, was found in the majority of the tumour cells in FCL-F and in MCL, but not in BL. Whereas the extent of Bcl-x expression correlated positively with the growth rates, an inverse correlation was observed between the percentages of c-Myc-positive tumour cells and the growth rates of the tumours. We conclude that normal and malignant lymphoid tissues have a distinct pattern of apoptosis and that expression of Bcl-x and c-Myc in B cell lymphoma is differentially regulated.

Prognostic significance of Bcl-2 expression and p53 nuclear accumulation in colorectal adenocarcinoma

The products of bcl-2 and p53 genes are involved in the regulation of apoptosis and proliferation and have been associated with prognosis in several malignancies, including colorectal adenocarcinoma. Although 2 European studies have reported a prognostic significance of Bcl-2 expression in colorectal adenocarcinomas, a study from the United States did not observe such an association. Therefore, we used immunohistochemistry to evaluate the prognostic significance of Bcl-2 expression, p53 nuclear accumulation and their concomitant expression in 134 US patients with colorectal adenocarcinoma. Antigen retrieval was required for adequate detection of Bcl-2 expression. Fifty percent of the colorectal tumors were classified as expressing Bcl-2, and Bcl-2 expression was associated with longer patient survival. Antigen retrieval was not necessary for detecting nuclear accumulation of p53 by immunohistochemistry. Nuclear accumulation of p53 was detected in 44% of colorectal adenocarcinomas and was associated with decreased patient survival. Tumors that did not express detectable levels of Bcl-2 but exhibited nuclear accumulation of p53 were associated with the shortest patient survival (log rank, p = 0.001). Multivariate Cox regression analysis demonstrated that Bcl-2 expression (p = 0.018), p53 nuclear accumulation (p = 0.024) and regional lymph-node metastasis (p = 0.005) were independent prognostic factors. Although a trend toward an inverse correlation between Bcl-2 and p53 expression was observed, the prognostic value of Bcl-2 expression was independent of p53 status. Thus, assessment of both Bcl-2 and p53 status may be valuable in predicting the prognosis of patients with colorectal adenocarcinomas.

Evidence that expression of a mutated p53 gene attenuates apoptotic cell death in human gastric intestinal-type carcinomas in vivo

To examine in vivo the validity of the results of experiments in vitro, we analyzed the relationship between p53 gene status and apoptotic cell death of human gastric intestinal-type adenocarcinomas. Surgical specimens were classified into two categories: 18 gastric cancers with nuclear p53 protein (A), and 17 gastric cancers without nuclear p53 protein (B). Polymerase chain reaction-single strand conformation polymorphism disclosed a shifted band that corresponded to a mutation in the p53 gene in 13 cases (72%) in category A and 3 cases (18%) in category B, the frequency being significantly higher in the former (P < 0.05). Apoptotic cells were identified from routinely stained sections and by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL). The TUNEL index [TI; (the number of TUNEL-positive apoptotic cells/the total number of tumor cells) x 100] was 3.8 +/- 1.4% in category A and 4.9 +/- 1.2% in category B, the value being significantly lower in the former (P < 0.05). The proliferating cell nuclear antigen index, defined similarly to the TI, was 56.4 +/- 16.3% in category A, and it was significantly higher than that in category B (P < 0.05). The immunohistochemically detected expression of p21CIP1/WAP1 did not differ between the two categories, while Bax-positive tumor cells were more frequently detected in category A. These results indicate that (1) expression of a mutated p53 gene attenuates apoptotic cell death of gastric cancer, in accordance with the previous in vitro finding that p53 gene mutation provides a possible selective advantage for tumor cell proliferation, and (2) apoptosis is related not only to expression of p53 and the stage of the cell cycle, but also to p53-independent and cell cycle-independent events.

Differential p53 protein expression in stomach adenomas of gastric and intestinal phenotypes: possible sequences of p53 alteration in stomach carcinogenesis

In a comparative study, the expression of p53 protein was investigated in intestinal- and gastric-type adenomas of the stomach. The former is a conventional type, which is well known to be a premalignant lesion of the stomach, but the latter is a rare, more recently noted entity. Of 28 intestinal-type adenomas, 17 (60.7%) contained more than 5% of p53 immunoreactive cells. In these adenomas, the extent of positivity for p53 protein was significantly higher in high-grade dysplasia than in low-grade dysplasia (P < 0.05), suggesting that p53 alteration plays a part in the dysplastic progression of intestinal-type adenomas. Among 18 gastric-type adenomas in which most of the tumour cells displayed gastric-type mucin, substantial expression of p53 protein was found only in the 3 tumours with high-grade dysplasia. Thus, the incidence of p53 expression was significantly higher in intestinal-type adenomas than in gastric-type adenomas (P < 0.01). These results suggest that p53 gene alteration is an earlier event in the gastric carcinogenetic sequence with the intestinal phenotype than in that with the gastric phenotype.

Apoptosis and gastrointestinal pharmacology

Apoptosis is a fundamental biological process that regulates cell number and removes cells that are neoplastic or infected by viruses. This review summarises present knowledge of the mechanisms and genetic regulation of apoptosis in the gastrointestinal tract and highlights areas of pharmacological relevance. In the intestine, apoptosis occurs in the crypt and possibly at the villus tip. Abnormal apoptosis plays a role in a number of gastrointestinal disease including colorectal cancer. The effects of cytotoxic drugs, chemical carcinogens, nonsteroidal anti-inflammatory drugs, short-chain fatty acids, bile salts and anthraquinolones on apoptosis in the gastrointestinal tract are reviewed.