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     

Colchicine-induced cell death and proliferation in the olfactory epithelium and vomeronasal organ of the mouse

 The cytotoxic agent colchicine induced apoptotic cell death and subsequent regeneration in the mouse olfactory epithelium and vomeronasal organ. The TUNEL method revealed the presence of many apoptotic bodies in the middle to basal region of the septal olfactory epithelium and vomeronasal organ near the boundary of the respiratory epithelium at 1 day after a single i.p. injection of colchicine (4 mg/kg b.w.). In some regions of the third and the fourth nasal turbinates, massive apoptosis was observed in the olfactory epithelium. Electron micrographs of the septum showed that immature olfactory cells and globose basal cells were killed by the colchicine and had been phagocytized by the supporting cells and macrophages. In the vomeronasal organ, immature sensory cells and precursors died in response to the colchicine. In response to cell death, active proliferation of precursor cells (globose basal cells) and subsequent regeneration of olfactory cells occurred in the olfactory epithelium and vomeronasal organ. Incorporation of the mitotic tracer BrdU by precursor cells reached its peak at 4 days after colchicine treatment in the vomeronasal organ, and at 6 to 7 days in the olfactory epithelium; however, in some regions in the third and the fourth nasal turbinates, where many olfactory cells and globose basal cells had died by colchicine effect, the regeneration did not occur even in 1 month, forming the epithelium of only supporting cells and horizontal basal cells. In the next month, these regions became normal olfactory epithelium. This suggests that the globose basal cells in the surrounding normal olfactory epithelium might invade these regions to give rise to the olfactory cells. Accepted: 2 February 1998     

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     

Frequency and distribution of DNA fragmentation as a marker of cell death in chronic liver diseases

 To study the early stages of cell death in various types of chronic liver injury, liver biopsies from a total of 26 patients, including 7 with chronic hepatitis C(CHC), 4 with chronic hepatitis B(CHB), 7 with alcoholic liver disease (ALD), 4 with autoimmune or drug hepatitis(AI/DH), and 4 with primary biliary cirrhosis(PBC), were examined by an in situ nucleotidyl transferase assay (ISNTA), which detects DNA fragmentation. Positive nuclei in hepatocytes and sinusoidal lining cells were counted in all parenchymal areas, excluding triads and areas of fibrosis, using a computer with Sigmascan software. The number of positive hepatocytes/mm² was similar in the biopsies of patients with CHC, CHB, ALD and AI/DH, but significantly lower in PBC. The number of positive sinusoidal lining cells/mm² was significantly greater in biopsies with CHC compared to CHB, ALD, AI/DH and PBC. Double staining revealed that the ISNTA-positive sinusoidal lining cells were also CD68 positive, indicating that they were Kupffer cells. The frequency of ISNTA positivity did not correlate with serum AST or ALT levels, steatosis, cell swelling or cirrhosis. ISNTA-positive hepatocytes were more frequent than acidophilic bodies in every disease category. We conclude that apoptosis may be a common pathway of cell death in different liver diseases, that the high frequency of DNA fragmentation in Kupffer cells in CHC suggests that during chronic hepatitis C infection activated Kupffer cells may be subject to regulatory control by apoptosis and that ISNTA is more sensitive than acidophilic bodies in assessing the degree of cell injury in the liver. Received: 17 February 1997 / Accepted: 18 March 1997     

Regulation of proliferation and apoptosis in sporadic and hereditary medullary thyroid carcinomas and their putative precursor lesions

C-cell hyperplasia (CCH) and medullary thyroid carcinoma (MTC) in patients affected by germline mutations of the RET oncogene represent an exceptional opportunity to study the regulation of proliferation and apoptosis during tumour initiation and progression. In 56 specimens [CCH, n=1; MTC with CCH, n=26; MTC, n=20; lymph-node metastasis (LNM), n=9] from 46 patients [multiple endocrine neoplasia type 2a (MEN2a), n=24; MEN2b, n=2; familiar MTC (FMTC), n=4; sporadic MTC, n=16] and 3 cases of non-neoplastic CCH, proliferation activity (MIB1), the rate of apoptosis [dUTP nick end labelling (TUNEL)] and expression of p53, bcl-2, bcl-x and bax were investigated and compared with clinical data. In MEN-associated CCH and small MTC, bcl-2 was strongly expressed, bcl-x was moderately expressed and bax was only weakly expressed. Advanced tumours and LNM did show a more heterogeneous bcl-2 staining accompanied by an increased bax expression and accelerated proliferation. The rate of apoptosis was extremely low in all investigated tumours. P53 was detectable in three patients with rapidly growing and extensively metastasising MTC. No somatic p53 mutations were found. Hereditary MTC with germline RET mutations at codon 918 (MEN2b) and codon 634 revealed a bias towards a higher proliferation activity at a younger age and are more frequently accompanied by LNM. CCH and MTC are characterised with a preponderance of bcl-2 as a factor blocking the programmed cell death. While MTC, in general, is a slowly growing tumour, a minority of tumours do progress rapidly with high proliferation. The factors leading to an accelerated tumour progression do not seem to take their effect via the regulation of apoptosis. Certain alterations of RET are supposed to have a direct or indirect implication on proliferation and, because of this, an effect on the clinical course. Received: 10 January 2000 / Accepted: 1 March 2000     

SIRT1 promotes proliferation and inhibits apoptosis of human malignant glioma cell lines

In mammalian cells, SIRT1 decreases PTEN acetylation and inactivates the AKT pathway in a SIRT1 deacetylase-dependent manner. However, the function of SIRT1 in glioma was unknown. SIRT1 reexpression or knockdown was induced in human glioma cell lines. The cell synchronization, BrdU labeling and mitotic index were detected. Subsequently, cell cycle, cell viability, apoptosis, cell growth and proliferation were analyzed. Our work identified that SIRT1-knockdown significantly delayed mitotic entry of glioma cells, inhibited its growth and proliferation, and promoted its apoptosis. The apoptosis was related to PTEN/PI3K/AKT signaling pathway. The results showed that SIRT1 might be a promoter factor on tumorigenesis of glioma through PTEN/PI3K/AKT signaling pathway.     

Prognostic significance of apoptosis and associated factors in oral squamous cell carcinoma

Tumour progression is characterised by an imbalance between cell proliferation and apoptosis. The aim of our study was to estimate the importance of proliferation and apoptosis associated parameters in primary squamous cell carcinomas (SCCs) of the oral cavity and oropharynx. For determination of apoptosis, the enzymatic labelling of DNA fragmentation with a terminal transferase reaction was used in 156 tissue samples of 107 patients, including corresponding lymph-node metastases in nine cases. P53, bcl-2, and Ki-67 were determined immunohistologically. P53 was detectable in 50.5% of the cases. Positive staining was associated significantly with decreased apoptosis (P<0.003). Bcl-2 was upregulated in 31.8% of the cases depending on the tumour grading (P<0.001) and correlated negatively with apoptosis (P<0.001). Proliferation (P<0.006) and apoptosis (P<0.03) were enhanced in larger tumours, though a direct correlation between these two parameters was not proven. Nevertheless, in contrast to the conventional tumour staging and grading, neither the expression of p53 or bcl-2 nor the apoptosis or Ki-67 measurements were able to predict survival or recurrence-free survival of the patients suffering from a SCC in the oral cavity or oropharynx. Our observations suggest that the function of wild-type p53 to induce apoptosis is lost in at least half of the SCCs under study and that the physiological function of bcl-2 as potent inhibitor of apoptosis is widely preserved in oral SCC. Received: 27 April 1999 / Accepted: 31 August 1999     

Galectins: versatile modulators of cell adhesion, cell proliferation, and cell death

 Lectins, or carbohydrate binding proteins, recognize specific oligosaccharide structures on glycoproteins and glycolipids. Several families of animal lectins have been identified; for some of these lectins, functions such as leukocyte adhesion and microbial opsonization have been described. The galectins are a family of lectins found in species ranging from sponges and nematodes to humans. Members of the galectin family have been proposed to mediate cell adhesion, to regulate cell growth, and to trigger or inhibit apoptosis. The expression pattern of different galectins changes during development, and this pattern is also altered at sites of inflammation and in breast, colon, prostate, and thyroid carcinomas. In addition, the level of expression of some galectins by tumor cells has been shown to be correlated with metastatic potential. The mechanisms by which galectins exert these diverse effects remain largely unknown. Some glycoprotein counterreceptors recognized by certain galectins have been identified; this is an important first step in understanding the cell-type specific effects of different galectins. This review discusses the way in which the modulation of galectin activity may affect strategies for treatment of a variety of human diseases, including autoimmunity and cancer. Received: 4 April 1997 / Accepted: 24 September 1997     

Proliferation not apoptosis as a prognostic indicator in retinoblastoma

 The balance between proliferation and cell death is the major determinant of tumour growth. We analysed the proliferative and apoptotic indices (PI and AI, respectively) of 33 children with retinoblastoma. PI and AI were assessed by immunohistochemistry for Ki-67 antigen and TUNEL staining, respectively. The mean PI was 21.0±21.1%, and higher PI was associated with more advanced tumour stage (P<0.0001) and poor clinical outcome (P<0.05). Patients in whom amplified N-myc oncogene was found (n=6) determined by the multiplex polymerase chain reaction tended to have a higher PI (37.6±27.2%) than those without amplified N-myc (n=27; PI=17.3±18.1). A PI value of over 40% was clearly associated with an unfavourable prognosis. The AI, however, did not correlate with any of the other variables analysed. The findings suggest that proliferation, but not apoptosis, is of critical significance in retinoblastoma biology. PI, as determined by the Ki-67 antigen labelling index, seems to be a relevant histopathological parameter that can predict the clinical outcome of retinoblastoma. Received: 9 November 1998 / Accepted: 24 November 1998     

胸腺肿瘤组织中EB病毒、细胞增殖和凋亡的检测

目的 研究胸腺肿瘤在广州５所医院的发病情况,与ＥＢ病毒（ＥＢＶ）感染是否相关以及肿瘤细胞增殖和凋亡的等级,方法 以４３例胸腺肿瘤和７例胸腺增生组织主研究对象,采用原位分子杂交检测ＥＢ病毒编码的ＥＢＥＲｓ,免疫组化ＬＳＡＢ法检测ＥＢＮＡ－１,ＬＭＰ－１,ＰＣＮＡ,ｂｃｌ－２和ｐ５３原位细胞凋亡（ＴＵＮＥＬ）方法检测细胞凋亡,结果 （１）胸腺疾病在广州５所医院活检中仅占有０．０５７％,其中肿瘤占７４．     

不同浓度腐胺对人肝细胞增殖及凋亡的影响

目的探讨不同浓度腐胺对体外培养人正常肝细胞增殖、凋亡的影响。方法将体外培养的人正常肝细胞株LO2分为腐胺组与对照组,不同浓度腐胺组以含腐胺浓度分别为0.25、0.50、1.00、10.00、20.00、40.00、80.00、160.00、320.00、640.00μg/mL完全培养基培养细胞,对照组以不添加腐胺完全培养基培养细胞。对照组与不同浓度腐胺组处理的LO2细胞培养12 h后,再以四唑化合物电子耦联显色法（MTS）、流式细胞技术（FCM）分别测定细胞的增殖活性（用吸光度值表示）与凋亡率,并对两组数据进行相关性分析。结果 MTS结果显示,0.25、0.50、1.00、10.00、20.00μg/mL浓度腐胺组LO2细胞吸光度值均较对照组（0.474±0.022）升高,差异有统计学意义（P〈0.05）,并且1.00μg/mL浓度时达到峰值（0.834±0.012）;80.00μg/mL及以上浓度腐胺组LO2细胞吸光度值较对照组降低,差异有统计学意义（P均〈0.01）;40.00μg/mL腐胺组LO2细胞吸光度值（0.477±0.009）与对照组比较,差异无统计学意义（P〉0.05）。流式细胞技术结果显示,0.25、0.50、1.00、10.00、20.00μg/mL浓度腐胺组LO2细胞凋亡率均较对照组（15.23±1.82）%降低,差异有统计学意义（P〈0.05）,并且1.00μg/mL腐胺组细胞凋亡率达到最低值（2.30±1.00）%;80.00μg/mL及以上浓度腐胺组LO2细胞凋亡率较对照组升高,差异有统计学意义（P均〈0.01）;40.00μg/mL腐胺组LO2细胞凋亡率（16.10±1.45）%与对照组比较,差异无统计学意义（P〉0.05）。相关性分析结果显示,各组浓度腐胺处理LO2细胞其细胞增殖与凋亡率呈负线性相关关系（r=-0.989,P=0.000）。结论低浓度（0.25-20.00μg/mL）腐胺对人正常肝LO2细胞增殖有促进作用,而较高浓度（80.00μg/mL及以上）的腐胺则出现明显的诱导凋亡作用,低浓度腐胺促进细胞增殖可能是通过抑制细胞凋亡而实现。     

Mitogen-activated protein kinases and apoptosis in PIN

 Mitogen-activated protein (MAP) kinases are key elements of the signalling systems needed to transduce different extracellular messages into cellular responses. At least three parallel MAP kinase pathways have been identified: one, stimulated by serum and growth factors to activate extracellular signal-regulated protein kinases (ERKs) by dual tyrosine and threonine phosphorylation, triggers cell proliferation or differentiation; the other two, induced by a variety of cellular stresses to activate c-jun N-terminal kinases (JNKs) and reactivating kinase (p38/RK), result in growth arrest and induction of apoptosis. Mitogen-activated protein kinase phosphatases (MKPs) inactivate MAP kinases through dephosphorylation and, thus, can modulate the MAP kinase pathways. Expression of JNK-1, ERK-1, p38/RK and MKP-1 proteins was investigated by immunohistochemistry and expression of MKP-1 mRNA by in situ hybridisation in 50 cases of high-grade prostatic intraepithelial neoplasia (PIN), thought to represent the precursor of prostate cancer. The frequency of apoptotic cells was also determined in these cases. Overexpression of the three MAP kinases and MKP-1 mRNA was found in all cases of high-grade PIN compared with normal prostate. Immunoreactivity for MKP-1 protein was found to be as intense as in normal glands in 30% and weaker in 56% of the PIN cases. Fourteen per cent of PIN cases did not stain with MKP-1 antibody. The proportion of apoptosis was significantly higher (P < 0.008) in PIN lesions that did not express MKP-1 protein than in those that did. These results are consistent with our previous demonstration of preferential inhibition of the apoptosis-related kinases by MKP-1 and further support the contention that MKP-1, even in PIN, may shift the balance existing between cell proliferation and death. When expressed, it may inhibiting those pathways that lead to apoptosis. Received: 27 August 1997 / Accepted: 29 December 1997     

3-溴丙酮酸对人卵巢癌细胞增殖和凋亡的影响

目的 观察3-溴丙酮酸对人卵巢癌SK-OV-3细胞株增殖和凋亡的影响,探讨3-溴丙酮酸对人卵巢癌细胞的体外抗肿瘤效应.方法 MTT比色法和集落形成试验检测3-溴丙酮酸对SK-OV-3细胞的增殖抑制作用;采用投射电镜观察3-溴丙酮酸作用后的SK-OV-3细胞形态学改变;流式细胞术检测3-溴丙酮酸作用后SK-OV-3细胞的凋亡,并对细胞周期的变化进行分析.结果 3-溴丙酮酸对SK-OV-3细胞的增殖有明显的抑制作用,具有时间（一段时间内）和剂量依赖性（P＜0.05）.3-溴丙酮酸主要将细胞阻滞于G0/G1,S期细胞明显减少.结论 3-溴丙酮酸对SK-OV-3细胞增殖的抑制效应具有时间依赖性（一段时间内）和剂量依赖性,并可诱导其凋亡.     

Expansion of T cells negative for CD28 expression in hiv infection. Relation to activation markers and cell adhesion molecules,and correlation with prognostic markers

  CD28 is a transmembrane glycoprotein that provides T cells with an essential co-stimulatory signal during antigen presentation. Using flow cytometry, we document here an expansion of CD28^– T cells in HIV infection. Whereas the percentage of CD4⁺CD28⁺ T cells among total lymphocytes was decreased, a small increase of the percentage of CD4⁺CD28^– T cells was observed. In the CD8⁺ subset, there was a marked expansion of CD8⁺CD28^– T cells. An increased percentage of CD8⁺ T cells positive for HLA-DR was found in both CD28⁺ and CD28^– cells. Results were similar for CD38 expression. HIV infection was also distinguished by a shift from LFA-1^lowCD28^low to LFA-1^highCD28^high and LFA-1^high-CD28^neg expression pattern on CD8⁺ T cells. Negative correlations were found between percentage and absolute number of CD8⁺CD28⁺ T cells and several serum parameters usually associated with poor prognosis (IgA, IgE, β2-microglobulin and HIV-1 p24 antigen). Thus, HIV infection is characterized by a marked expansion of CD28^– T cells with an abnormal expression of activation markers and cell adhesion molecules. In addition, CD8⁺CD28⁺, but not CD8⁺CD28^– or total CD8⁺ T cell numbers, correlated with the levels of established serological markers of disease severity or progression and may, therefore, have predictive value. Received: 1 November 1995     

A simple, precise and economical microdissection technique for analysis of genomic DNA from archival tissue sections

 Formalin-fixed and paraffin-embedded tissues are valuable resources for retrospective analysis of the molecular changes in DNA present in tumour tissues. One common problem that precludes an accurate DNA analysis in a human tissue sample is cellular heterogeneity. We have developed a simple and inexpensive, but micrometrically precise, microdissection technique that allows for selective isolation of minute cell clusters and even single cells from archival tissue sections. The features of our technique include use of a 30G1/2 needle affixed to a mechanical micromanipulator as a dissector sharp enough to be used for dissection of even single cells and use of the stage and focus control knobs of the microscope to scrape the target cells instead of moving the needle during microdissection. The main advantages of this technique over the current methods lie in its simplicity, low cost, easy handling and precision. Received: 24 March 1998 / Accepted: 27 May 1998     

Cell proliferation and apoptosis of thyroid follicular cells are involved in the involution of experimental non-tumoral hyperplastic goiter

 It is unknown whether cells in the midportion of Meckel’s cartilage undergo transformation into other kinds of cell or whether resorption of cells occurs during development. Therefore, the midportion of Meckel’s cartilage from the mouse and the rat was subdivided into anterior and posterior portions. The ultimate fates of these tissues were analyzed with a focus on resorption-related cells, death of chondrocytes by apoptosis, and transformation of the chondrocytes themselves. Cellular and extracellular features of mouse Meckel’s cartilage were observed after von Kossa’s staining and staining for acid phosphatase (APase) activity, as well as by light and electron microscopy. To identify resorbing cells, immunostaining specific for macrophages and staining for tartrate-resistant acid phosphatase (TRAP) were performed. The DNA nick end-labeling (TUNEL) method was used for the detection of death of chondrocytes by apoptosis. The replacement of the extracellular matrix of rat Meckel’s cartilage was examined with double immunofluorescence staining for type I and type II collagens. When the anterior midportion from embryonic mice on day 18 was examined after von Kossa’s staining, it was clear that the extracellular matrix had already calcified and vascularization had been initiated that reflected the calcified matrix. TRAP staining and immunostaining for macrophages revealed two types of osteoclast and macrophages that were involved in resorption of the matrix. In the posterior midportion, no vascular invasion was evident, and chondrocytes were transformed directly into fibroblastic cells by phenotypic conversion. In such cells we found reaction products specific for APase activity, suggestive of the intracellular degradation of fine collagenous fibrils. Double immunofluorescence staining showed that cartilage-specific type II collagen was replaced by type I collagen with the phenotypic transformation to fibroblastic cells. There were no significant changes in the number of TUNEL-positive apoptotic cells from day 17 of gestation to day 6 after parturition. Death of chondrocytes by apoptosis was not, therefore, involved directly in the disappearance of Meckel’s cartilage. These results in the posterior midportion served as an instance of phenotypic switches in differentiated cells from chondrocytes to fibroblast-like cells. The present study indicates that there is a difference between the ultimate fate of cells in the posterior part and that of cells in the anterior part in the midportion of Meckel’s cartilage in the mouse and rat. Accepted: 8 January 1998     

Programmed cell death in the interdigital tissue of the fetal mouse limb is apoptosis with DNA fragmentation

Background: Programmed cell death is an essential event during mammalian morphogenesis which eliminates unnecessary cells to accomplish histogenesis and organogenesis. Cell death in interdigital spaces of the developing limb is a classical example of morphogenetic cell death. We investigated whether classical programmed cell death in the interdigital tissue of the developing limb in mice is apoptosis with fragmentation of nuclear DNA and also examined sequentially the occurrence of programmed cell death and cell proliferation in the developing limb of mouse fetuses to analyze their interrelation. Methods: We examined the occurrence of apoptotic cell death in the developing limbs of mouse fetuses by using Nile blue sulphate staining, agarose gel electrophoresis for detecting DNA laddering, and a cytochemical labeling of DNA fragmentation. We also labeled proliferating cells using BrdU/anti-BrdU immunohistochemistry and examined the interrelation between apoptotic programmed cell death and cell proliferation. Results: DNA ladders, a biochemical evidence of apoptosis, were detected in DNA extracts from the interdigital tissue of day 13 mouse fetuses by agarose gel electrophoresis. Programmed cell death and DNA fragmentation were detected by Nile blue staining and cytochemical labeling of DNA fragmentation, respectively, in the interdigital mesoderm and in the regions of presumptive joints of the digit. BrdU/anti-BrdU immunohistochemistry for identifying proliferating S-phase cells revealed that interdigital mesenchymal cells cease DNA synthesis before programmed cell death and DNA fragmentation begin. Conclusions: We confirmed that both cytological apoptotic alterations and fragmentation of nuclear DNA occur in the interdigital tissue and presumptive joint areas of fetal mouse limbs, and they appear to play a significant role in the separation of digits as well as the formation of joint cavities. © 1995 Wiley-Liss, Inc.     

人参皂苷Rg1对缺氧复氧BMSCs增殖和凋亡的影响

目的　探讨人参皂苷Rg1(ginsenoside Rg1)对缺氧复氧BMSCs增殖和凋亡的影响,并探讨其可能机制。 方法　实验分为BMSCs正常对照组、BMSCs缺氧复氧组(Model组)、人参皂苷Rg1 1×10-7、1×10-6 、1×10-5 mol/L处理组、尼莫地平2.5×10-7 mol/L处理组（阳性对照组）。各组分别于缺氧复氧12h前加入完全培养基（正常对照组、Model组）、人参皂苷Rg1（人参皂苷Rg1各处理组）、尼莫地平（阳性对照组）。建立缺氧复氧BMSCs模型。采用TUNEL法检测各组的细胞凋亡率,免疫荧光和免疫印迹技术定性定量检测各组增殖细胞核抗原(proliferating cell nuclear antigen,PCNA)、Bcl-2、Bax的表达情况。 结果 TUNEL结果显示,BMSCs正常对照组未见明显凋亡细胞,Model组可见明显的凋亡细胞,与Model组比较,其余各处理组凋亡细胞数量均减少,以人参皂苷Rg1（1×10-5mol/L）组最为明显。免疫荧光和免疫印迹结果显示,BMSCs正常对照组可见少量的PCNA 、bcl-2、bax表达;Model组的PCNA 、bcl-2的表达减少,但bax的表达显著增高,bcl-2/bax比值降低;与Model组比较,人参皂苷Rg1各组PCNA 、bcl-2表达均呈不同程度的增高,而bax表达呈现相反的趋势,bcl-2/bax比值增高,以Rg1 (1×10-5 mol/L)组最为明显。 结论 人参皂苷Rg1预处理对缺氧复氧BMSCs具有保护作用,其机制可能与下调bax的表达,上调PCNA 、bcl-2的表达,抑制BMSCs凋亡和促进BMSCs增殖有关。     

Roles of K+ channels in regulating tumour cell proliferation and apoptosis

K⁺ channels are a most diverse class of ion channels in the cytoplasmic membrane and are distributed widely in a variety of cells including cancer cells. Cell proliferation and apoptosis (programmed cell death or cell suicide) are two counterparts that share the responsibility for maintaining normal tissue homeostasis. Evidence has been accumulating from fundamental studies indicating that tumour cells possess various types of K⁺ channels, and that these K⁺ channels play important roles in regulating tumour cell proliferation and apoptosis, i.e. facilitating unlimited growth and promoting apoptotic death of tumour cells. The potential implications of K⁺ channels as a pharmacological target for cancer therapy and a biomarker for diagnosis of carcinogenesis are attracting increasing interest. This review aims to provide a comprehensive overview of current status of research on K⁺ channels/currents in tumour cells. Focus is placed on the roles of K⁺ channels/currents in regulating tumour cell proliferation and apoptosis. The possible mechanisms by which K⁺ channels affect tumour cell growth and death are discussed. Speculations are also made on the potential implications of regulation of tumour cell proliferation and apoptosis by K⁺ channels.