Decreased programmed cell death in the uterine cervix associated with high risk human papillomavirus infection

The relationship between apoptosis, apoptosis regulatory proteins, cell proliferation and human papillomavirus infection during various phases of tumor progression in the uterine cervix was studied. Apoptosis was defined by morphological criteria and the TUNEL assay. Expression of p53, bcl-2, bax, cyclin D1, Ki 67 and E6 protein was evaluated by immunocytochemistry. Presence of mutant p53 was detected using a mutant specific ELISA. Type of HPV infection was determined by PCR using type specific primers. Apoptosis showed significant negative correlation with increasing histological abnormality (p=0.0005). Higher tumor cell proliferation was associated with increasing histological abnormality (p=0.001 for Ki 67 and cyclin D1). There was significant correlation between histological grade and immunoreactivity of p53 (p=0.0001 ) and bcl-2 (p=0.0002). However, mutant p53 was expressed by only 12 of the 230 samples. Expression of bax and the bax/bcl-2 ratio showed an inverse correlation to histological grade (p=0.0003 and 0.0001, respectively). There was also an inverse correlation between extent of apoptosis and immunoreactivity of p53 (p=0.0001) and bcl-2 (p=0.0001). A significant positive correlation between expression of the bax protein and apoptosis was evident (p=0.0001). HPV infection significantly correlated to the extent of histological abnormality (p=0.0001). High risk HPV-E6 protein also showed this significant correlation (p=0.0002). There was an inverse correlation between apoptosis and HPV infection (p=0.0002). High risk HPV infection was associated with decreased apoptosis and also increased human cell proliferation. Lowest levels of bax/bcl-2 ratio was also associated with HPV 16 and 18 infection (p=0.0001). Modulation of apoptosis and apoptotic regulatory proteins by high risk HPV infection may be an important factor in the development of cervical cancer.     

Apoptosis, angiogenesis and proliferation: trifunctional measure of tumour response to radiotherapy for oral cancer

Local recurrence is a significant problem following radiotherapy in oral carcinoma and hence there is a paramount need for predictive markers. This study therefore analysed the predictive value of pre-treatment status of angiogenesis, apoptosis, expression of apoptosis regulatory p53, bax and bcl-2 proteins as well as tissue proliferation in relation to tumour response to radiotherapy. Sixty-nine histologically defined invasive carcinoma lesions were included in the study. Extent of apoptosis was defined morphologically and by the TUNEL (Tdt-mediated dUTP biotin nick end labelling) assay. Expression of apoptosis regulatory p53, bax and bcl-2 proteins were evaluated by immunocytochemistry. Mutant p53 protein was detected using a mutant p53-specific ELISA. The extent of tissue proliferation was evaluated by cyclin D1 expression. Angiogenesis was evaluated by CD34 antigen expression. All patients were treated with radical radiotherapy and followed up for 36 months. High levels of p53 protein detected by immunocytochemistry were found to be associated with poor response to treatment or disease relapse. Detection of mutant p53 protein also showed significant association with poor prognosis. Low levels of angiogenesis had a correlation with recurrence status. Tumours showing less vascularisation as well as increased apoptosis had a poor prognosis. Expression of p53 and bcl-2 proteins showed direct correlation with angiogenesis. There was no correlation between clinical status and any of the experimental parameters with histopathological grades of invasive lesions. Presence of mutant p53 protein is suggestive of poor tumour response to radiotherapy. Expression of p53 and increased apoptosis in less vascularised tumours is associated with treatment resistance. A predictive assay based on these results designed to analyse individual tumour samples showed presence of apoptotic cells near the vasculature to be indicative of good prognosis, while absence of apoptotic cells or highly proliferative cells and/or expression of bcl-2 protein in cells around the vasculature to be an indicator of poor prognosis.     

Expression of bcl-2 and bax in chewing tobacco-induced oral cancers and oral lesions from India

Deregulation of oncogenes and tumor suppressor genes involved in apoptosis has been associated with tumor development and progression. To investigate the involvement of apoptosis regulating proteins in oral cancer in Indian patients, primarily associated with chewing tobacco habits, immunohistochemical expression of bcl-2 and bax was examined in 63 oral squamous cell carcinomas, and 31 putative premalignant lesions. Our studies revealed overexpression of tumor specific cytoplasmic bcl-2 in 56% and bax in 43% oral cancers. The oral cancers in the Indian patients are preceded by premalignant oral lesions; hence oral lesions were examined for bcl-2 and bax expression. We observed aberrant expression of bcl-2 in 16% oral lesions comprising leukoplakias and SMF and bax in 55% oral lesions. We have already reported, p53 expression in these oral cancers and lesions. It was noteworthy that 30% oral cancers demonstrated a p53+bcl2+ pattern, and 14% samples exhibited p53+bcl2+bax+ pattern. However, none of the oral lesions showed concurrent deregulation of p53 and bcl-2 or all the three genes. Interestingly 45% oral lesions were p53-bax+ as compared to 18% oral cancers; while 39% oral lesions were bcl2-bax+ as compared to 14% oral cancers, indicating overexpression of bax in oral lesions, in the absence of p53 and bcl-2 proteins. Significant correlation was observed between positive nodal status and bcl2+ (p=0.047) and p53+bcl-2+ (p=0.01) in oral cancers. Kaplan Meier survival analysis showed significantly (p=0.059) higher survival in patients with p53- oral tumors than with p53+ tumors. Our studies thus indicate frequent overexpression of apoptosis regulators bcl-2, bax and p53 proteins in oral cancers, and a subset of oral lesions, representing early events in oral car-cinogenesis. The aberrant bcl-2 expression and loss of p53 function observed, may play an important role in the tumorigenesis of oral cancers by allowing escape from apoptosis and enabling additional genetic alterations to accrue.     

Involvement of cyclin D1-cdk5 overexpression and MCM3 cleavage in bax-associated spontaneous apoptosis and differentiation in an A253 human head and neck carcinoma xenograft model.

Time-dependent ladder-type DNA fragmentation and morphological alterations consistent with apoptosis were observed among A253 human head and neck squamous cell carcinoma (HNSCC) cells in nude mice from 15 to 18 days after transplantation, without any drug treatment. No evidence of ladder-type DNA fragmentation was detected in A253 cells in vitro or in normal nude mouse tissues (skin and muscle). Our aim was to explore molecular factors associated with such spontaneous apoptosis. Bcl-2 protein expression decreased, while bax protein expression increased from day 9 after transplantation. Moreover, altered expression of bcl-2 and bax was accompanied by the increased proteolytic cleavage of poly(ADP-ribose) polymerase (PARP). Time-dependent dephosphorylation of Rb, followed by proteolytic cleavage, was also observed from day 9 after transplantation. The data indicate that the caspase-3 activation and cleavage of Rb protein may represent important steps in the regulation pathway of bax-mediated spontaneous apoptosis. Interestingly, the time-dependent activation of spontaneous apoptosis was almost simultaneous with the induction of differentiation and increased expression of several differentiation-associated regulatory proteins. An increased expression of cyclin D1 and cyclin-dependent kinase-5 (cdk5) was observed from day 9 after transplantation, whereas only slight alteration of cdk4 expression was found. The time-dependent activation of cyclin D1 and cdk5 preceded both the induction of ladder-type DNA fragmentation and increased keratin pearl formation. Furthermore, MCM3 was cleaved early in spontaneous apoptosis and differentiation. Our observations suggest the involvement of cyclin D1-cdk5 overexpression and MCM3 cleavage in bax-mediated spontaneous apoptosis and differentiation in A253 xenografts. P53 and WAF1 proteins were not expressed in the xenografts, indicating that the changes in the regulatory proteins during apoptosis and differentiation were not p53 or WAF1 dependent.     

Androgen receptor expression in relation to apoptosis and the expression of cell cycle related proteins in prostate cancer

The expression of several genes involved in the regulation of cell cycle and apoptosis may be regulated via the androgen receptor (AR) in the prostate. AR may have a role in the prognosis of prostatic carcinoma. The aim was to examine AR expression status and its relationship with markers of proliferation, apoptosis and cell cycle control in prostate cancer. Expression of AR, bcl-2, bax, Ki-67 and p53 was examined in paraffin-embedded tissues from 50 cases of prostate carcinoma by immunohistochemistry and evaluated using an index of staining. Detection of apoptotic cells was performed by TUNEL method. Correlation between AR expression and apoptosis, proliferation index, bcl-2, bax and p53 and also clinicopathological parameters including stage, pathological grade and Gleason score were determined. AR expression was observed in all cases with mean expression of 81%±15 and mean staining index of 141±65. No correlation was found between AR expression and apoptosis detected in patients. The mean AR staining index was 170±72 in bcl-2 positive tumors versus 120±53 in bcl-2 negative tumors showing a significant association between AR and bcl-2 expression (p=0.015). AR expression also showed a significant association with bcl-2/bax ratio (r=0.321, p=0.023) and Ki-67 proliferation staining index (r=0.396, p=0.004). Although a significant correlation between Ki-67 and p53 with differentiation status of the tumors was observed (p<0.004) no correlation was found with AR. AR expression showed no prognostic value regarding its correlation with stage and differentiation status of the prostate carcinoma. However, its significant correlation with Ki-67 and bcl-2 that are markers of cell survival suggest its contribution to tumor cell progression.     

Quercetin regulates growth of Ishikawa cells through the suppression of EGF and cyclin D1

Quercetin and other polyphenols have anti-carcinogenic and anti-tumorigenic activity in various organs, however, studies of this activity are lacking in endometrial cancer. We hypothesize that quercetin has anti-proliferative activity and the mechanisms of quercetin action may be through modulation of cell cycle and cell growth regulatory genes. To test this hypothesis, we treated endometrial cancer cells (Ishikawa cell line) with quercetin, and cell proliferation, expression of growth signal genes (EGF, VEGF, and TGF-alpha), cell cycle genes (p53, p21, p73, and cyclin D1), and apoptosis-related genes (bcl-2 and bax) were analyzed. Results of these experiments demonstrate that after a 7-day exposure to 1, 10 and 100 micro M of quercetin, growth of Ishikawa cells was inhibited by 3, 51 and 87%, respectively. The gene and protein expression data suggest that quercetin treatment (100 micro M) significantly decreased EGF and cyclin D1, whereas VEGF was up-regulated in Ishiwaka cell lines. Other genes such as TGF-alpha, p53, p21, p73, bcl-2 and bax were not significantly changed with quercetin treatment in Ishiwaka cell lines. The present study suggests that quercetin can suppress proliferation of Ishikawa cells through down-regulation of EGF and cyclin D1.     

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

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

p53, p16 and cyclin D1: molecular determinants of radiotherapy treatment response in oral carcinoma

Management of oral cancer by radiotherapy has witnessed promising advances in the past few years, with patient-tailored radio fractionation regimens. Different fractionation schedules, conventional and altered regimes, have been used in curative radiotherapy. Although contribution of biological markers on radio response has been evaluated, its unique influence on various radio fractionation schemes has not been accounted so far. Our study analyses a set of proteins that previously demonstrated radio response influence for their possible prognostic value in decision-making process between the respective fractionation schemes. Expression patterns of regulatory proteins such as p53, cyclin D1, p16, Cdk4, p21, Rb, bcl-2 and PCNA were determined by immunohistochemistry utilizing monoclonal antibodies in 125 patients who received curative radiotherapy dose. Among these 125 patients, 90 (72%) received altered fractionation, whereas 35 (28%) received conventional fractionation. p53 over-expression correlated with local treatment failure among the patients treated with conventional fractionation whereas cyclin D1 over-expression and p16 underexpression were associated with local treatment failure as well as overall survival in altered fractionation treated cases. Our findings suggest that wild-type p53 status may be an important parameter for achieving high local control in those patients undergoing conventional fractionation, where as intact p16 and cyclin D1 status may be beneficial for effective local control in patients who are treated with altered fractionation. Furthermore, it can be assumed that conventional fractionation employs p53-mediated apoptosis, whereas altered fractionation activates the functional G1 cell-cycle checkpoint for tumor growth suppression.     

Growth inhibition, cell-cycle arrest and apoptosis in human T-cell leukemia by the isothiocyanate sulforaphane

Glucosinolates (GL) can inhibit, retard or reverse experimental multistage carcinogenesis. When brassica plant tissue is broken, GLs are hydrolyzed by the endogenous enzyme myrosinase (Myr), releasing many products including isothiocyanates (ITC). Synthetic ITCs like sulforaphane exert chemopreventive effects against chemically induced tumors in animals, modulating enzymes required for carcinogens' activation/detoxification and/or the induction of cell-cycle arrest and apoptosis in tumor cell lines. To investigate the chemopreventive potential of ITCs while reproducing the circumstances of dietary contact with sulforaphane, we studied proliferation, apoptosis induction and p53, bcl-2 and bax protein expression in Jurkat T-leukemia cells by sulforaphane, the ITC generated in situ in a quantitative manner by Myr starting from glucoraphanin (GRA). Jurkat cells were treated with different doses of GRA-Myr mixture. Effects on cell growth or survival were evaluated by counting trypan blue-excluding cells. Cell-cycle progression, apoptosis and expression of p53, bax and bcl-2 proteins were analyzed by flow cytometry. Results were analyzed by two-sided Fisher's exact test. Sulforaphane, but not GRA, caused G(2)/M-phase arrest (P = 0.028) and increase of apoptotic cell fraction (P < 0.0001) in a time- and dose-dependent manner. Necrosis was observed after prolonged exposure to elevated sulforaphane doses. Moreover, it markedly increased p53 and bax protein expression, and slightly affected bcl-2 expression. These findings indicate that sulforaphane but not the native GL GRA can exert both protective and toxic effects inhibiting leukemic cell growth. Sulforaphane therefore deserves study as a potential chemopreventive/chemotherapeutic antileukemic agent.     

Modulation of cell cycle regulatory protein expression and suppression of tumor growth by mimosine in nude mice

Our previous results demonstrated that the plant amino acid mimosine blocked cell cycle progression and suppressed proliferation of human lung cancer cells in vitro by multiple mechanisms. Inhibition of cyclin D1 expression or induction of cyclin-dependent kinase inhibitor p21WAF1 expression was found in mimosine-treated lung cancer cells. However, whether mimosine may modulate the expression of these cell cycle regulatory proteins and suppress tumor growth in vivo is unknown. In this study, we examined the anti-cancer effect of mimosine on human H226 lung cancer cells grown in nude mice. Our results demonstrated that mimosine inhibits cyclin D1 and induces p21WAF1 expression in vivo. Furthermore, results of TUNEL analysis indicated that mimosine may induce apoptosis to suppress tumor growth in nude mice. Collectively, these results suggest that mimosine exerts anti-cancer effect in vivo and might be useful in the therapy of lung cancer.     

Cell cycle proteins and the development of oral squamous cell carcinoma

Expression of cell cycle regulatory proteins was evaluated in premalignant and malignant oral epithelial lesions, to test the hypothesis that protein regulation of the cell cycle may be altered in the development of oral squamous cell carcinoma. Archived paraffin-embedded specimens (n = 90) from 25 patients with recurrent or persistent lesions were evaluated in immunohistochemically stained sections for cell cycle regulatory proteins p53, Rb, Cyclin D1, p27, and p21. The cell cycle was also evaluated by expression of nuclear protein Ki 67. Sections were graded semiquantitatively using a 0-3 + scale to indicate the percentage of positively stained cells. The initial histologic diagnosis for 17/25 patients was either focal keratosis, mild dysplasia, or moderate dysplasia; the initial diagnosis for the remaining eight patients ranged from severe dysplasia to moderately differentiated squamous cell carcinoma. Thirty-three of 90 specimens showed positive p53 expression, 11 of which were dysplasias. Eighty-nine of 90 specimens, from all stages of disease, showed positive Rb expression. Twenty-three of 90 specimens showed positive Cyclin D1 expression, typically in the later stages (carcinoma) of a patient's disease. Eighty-four of 90 specimens showed positive p21 expression; while 55 of 90 specimens were positive for p27. In control mucosa, p27 was highly expressed, while Rb and p21 proteins were expressed at relatively low levels; p53 and Cyclin D1 proteins were largely absent. Generally, staining of p53, Rb, p21, and Ki 67 increased with time in serial biopsies, while p27 showed decreased staining with disease progression. These data show that cell cycle regulatory proteins are altered in both premalignant and malignant disease, and that protein phenotypes are heterogeneous. P53 expression is seen early, and Cyclin D1 expression is seen late in the development of oral premalignant and malignant disease. Expression of p53, Rb, p21 and Ki67 increased, while p27 decreased, with disease progression.     

Expression of bcl-2, bax,and bcl-XL proteins in azoxymethane-induced rat colonic adenocarcinomas

Using western blotting and immunochemical analysis, we investigated alterations in the expression of the apoptosis-related proteins bcl-2, bax, and bcl-X in colonic adenocarcinomas induced by subcutaneous injection of azoxymethane (AOM) (15 mg/kg body weight weekly for 2 wk) into male Sprague-Dawley rats. Expression of the apoptosis-repressor bcl-2 in the colonic tumors was significantly weaker (0.6-fold) than that in adjacent non-neoplastic mucosa. The expression of bax protein, an apoptosis accelerator, was significantly stronger (7.33-fold) in all the tumors than in the non-tumoral mucosa. bcl-X_L protein, which functions as a repressor of apoptosis, was significantly upregulated (3.23-fold) in all the tumors when compared with the non-neoplastic mucosa. There was no significant difference between the expression of these proteins in the non-neoplastic mucosa of the AOM-treated rats and in the normal mucosa of saline-treated control rats. As determined by immunohistochemical analysis, the tumor cells had more bax and bcl-X protein. These findings indicate that the regulation of the apoptosis-related proteins bcl-2, bax, and bcl-X_L was altered in the AOM-induced colonic neoplastic tissue. In terms of resistance to apoptosis, elevated levels bcl-X_L protein may have considerable meaning in this experimental model as well as in human colorectal cancer. Mol. Carcinog. 19:25–30, 1997. © 1997 Wiley-Liss, Inc.     

RhoE functions as a tumor suppressor in esophageal squamous cell carcinoma and modulates the PTEN/PI3K/Akt signaling pathway

Emerging evidence indicates that RhoE as novel member of the Rho GTPases family plays an essential role in carcinogenesis and tumor progression of human various tumors, but the functional significance of RhoE in human esophageal squamous cell carcinoma (ESCC) is still unclear. In the current study, RhoE expression in ESCC tissues and cells was examined, and the biological functions of RhoE in ESCC cells were determined. The results revealed that RhoE expression at mRNA and protein levels was significantly downregulated in ESCC tissues and cell lines (P??0.05). Additionally, we found that downregulation of RhoE expression in ESCC cells promoted cell proliferation, cell cycle progression, as well as cell invasion in vitro, and inhibited cell apoptosis. Conversely, upregulation of RhoE expression in ESCC cells inhibited cell proliferation, arrested cell cycle at G0/G1 phase, reduced cell invasion, and promoted cell apoptosis. Furthermore, the downregulation of RhoE expression significantly reduced PTEN level and enhanced pAkt level; however, elevation of RhoE expression markedly increased PTEN level and decreased pAkt level. Stepwise investigations demonstrated that overexpression of RhoE in ESCC cells increased the expressions of p27 and bax proteins but decreased the expressions of cyclin D1 and bcl-2 proteins. These data demonstrate that RhoE may play a driving role in the development and progression of ESCC, and targeting the RhoE may be an effective and feasible approach for treatment of ESCC.     

Topoisomerase-I inhibitors for human malignant glioma: Differential modulation of p53, p21, bax and bcl-2 expression and of CD95-mediated apoptosis by camptothecin and β-lapachone

β-lapachone and camptothecin are structurally unrelated agents thought to inhibit topoisomerase-I activity through distinct mechanisms. We find that β-lapachone is much more potent than camptothecin in inducing acute cytotoxic effects on human malignant glioma cells. Acute cytotoxicity induced by both drugs is apoptotic by electron microscopy, but not blocked by inhibitors of RNA or protein synthesis and not associated with changes in the expression of bcl-2, bax, p53, p21 or GADD45 proteins. In contrast, prolonged exposure of glioma cells to both drugs for 72 hr results in growth inhibition and apoptosis, with EC₅₀ values around 1 μM. None of 7 glioma cell lines tested were resistant to either drug. LN-229 cells which have partial p53-wild-type activity show enhanced expression of p53, p21 and bax protein, whereas bcl-2 levels decrease, after exposure to camptothecin. In contrast, β-lapachone increases bax protein expression in the absence of p53 activation. T98G cells are mutant for p53. In these cells, p53 levels do not change and p21 is not induced. bax accumulation in T98G cells is induced by both drugs, with bcl-2 levels unaltered. Surprisingly, ectopic expression of murine bcl-2 fails to abrogate the toxicity of either drug. Camptothecin, but not β-lapachone, sensitizes human malignant glioma cells to apoptosis induced by the cytotoxic cytokines, tumor necrosis factor-α and CD95 ligand. Thus, both drugs have potent anti-glioma activity that may be mediated by enhanced bax expression but is not inhibited by ectopic bcl-2 expression. Camptothecin-like agents are particularly promising for immunochemotherapy of malignant glioma using cytotoxic drugs and CD95 ligand. Int. J. Cancer 73:707–714, 1997. © 1997 Wiley-Liss, Inc.     

细胞凋亡调节与宫颈癌发生

目的：探讨子宫颈癌发生中的影响细胞凋亡的调节因素。方法：检测对象为194例经福尔马林固定石蜡包埋的手术切除标本，包括上皮内瘤样病变（CIN）78例[其中重度非典型增生（SD）41例；原位癌（CIS）37例]早期浸润癌（MIC）35例；大细胞非角化型浸润癌（IC）40例及正常宫颈鳞状上皮（NE）41例。凋亡细胞的检出使用TDT－mediated dUTP-biotin nick end labeling(TUNEL)方法；细胞凋亡相关基因蛋白p53、bcl-2、bax的表达采用单克隆抗体免疫组化ABC染色方法；HPV16、18型E6 DNA感染使用PCR方法进行检测。结果：1）凋亡细胞标记率仅在CIN呈现有意义地进行性减少（P＜0．01），癌变以后不再继续下降；2）在SD、CIS组，p53、bcl-2及bax基因蛋白的表达与TUNEL标记率呈现有意义地相关性变化（P＜0．05）；3）HPV16、18型E6 DNA感染与凋亡细胞及相关基因蛋白表达未呈现相关性改变。结论：以上结果提示细胞凋亡的改变与宫颈癌发生的早期过程有关，p53、bcl-2、bax基因蛋白参与其调节，而HPV16、18型E6 DNA感染与其未呈现直接的相关性。     

TSA对人肝癌细胞SMMC-7721的抑制作用及其机制

目的:研究去乙酰化转移酶抑制剂TSA对肝癌细胞SMMC-7721的作用及其机理。方法:利用细胞计数,流式细胞仪分析细胞凋亡及细胞周期,Tunel试验研究TSA对肝癌细胞SMMC-7721的作用;利用western研究TSA对肝癌细胞蛋白表达的影响。结果:TSA可明显抑制肝癌细胞SMMC-7721的生长,并可诱导细胞凋亡。可阻滞肝癌细胞SMMC-7721细胞周期于G0/G1期。可增加p53,p21,bax等基因的表达,降低BCL-2的表达。结论:去乙酰化转移酶抑制剂TSA可明显抑制肝癌细胞SMMC-7721的生长并诱导其凋亡,其主要通过调控一些肿瘤相关基因的表达起作用。     

Cellular manifestations of human papillomavirus infection in the oral mucosa.

BACKGROUND AND OBJECTIVES: Human papillomavirus infection has been suggested to play a role in the development of epithelial carcinomas, particularly those of the uterine cervix. Less information is available on the role of the virus in oral lesions. It has been proposed that the viral oncoproteins specifically complex with the products of cellular tumor suppressor gene, namely E6 with p53 and E7 with retinoblastoma gene product. Inactivation or mutation in p53 gene is also known to result in loss of control over the cell cycle and increases in tumor proliferation rates. The present study examines the role of HPV infection in relation to p53 and the extent of the tumor proliferative compartment reflected by cyclin D1 and Ki-67 expression during various phases of tumor progression in the oral epithelium. METHOD: Nonisotopic in situ hybridization (NISH) was performed to detect HPV 6/11 and 16/18. Expression of p53, cyclin D1, Ki-67, and the HPV 16/18 E6 protein were detected by immunocytochemistry. RESULTS: There was significant correlation between the extent of histological abnormality and HPV infection. A correlation (r = 0.250, P = 0.0089) was evident between the presence of HPV 16 and occurrence of invasive cancer. Expression of the tumor suppressor p53 protein also showed significant positive correlation with histology (r = 0.475, P = 0.00004). The tumor proliferative fraction also increased with the extent of histological abnormality (r = 0.387, P = 0.0003 for cyclin D1 and r = 0.463, P = 0.0001 for Ki 67). Accumulation of p53 and increase in tumor proliferation also correlated to the presence of HPV infection (r = 0.511, P = 0.00003 for p53; r = 0.478, P = 0.00002 for cyclin D1 and r = 0.521, P = 0.00004 for Ki-67). CONCLUSIONS: The present study thus demonstrates the importance of HPV infection in oral tissue. Expression of the high-risk HPV 16/18 E6 protein also appears to be a critical event along with aberrant p53 expression. These results are of significance to the molecular epidemiology of oral cancer and may also be used to supplement and elaborate the diagnosis of oral lesions.     

P21 and Bax expression in cutaneous malignant melanomas: correlation with histologic prognostic parameters

In response to DNA damage, p53 accumulates and regulates expression of several genes, including cyclin-dependent kinase inhibitor p21. Cells then undergo p21 dependent cell cycle arrest, which allows DNA damage repair and apoptosis. Bax is a death promoter member of the bcl-2 family which plays a central role in the regulation and commitment to programmed cell death. Breslow thickness is the most important factor in predicting prognosis for cutaneous malignant melanoma. In order to define the role of cyclin dependent kinase inhibitors and apoptosis regulators in invasion of malignant melanoma we investigated the expression of p21 and bax proteins. We observed that significant high p21 expression was associated with increasing Breslow thickness (Spearman correlation analysis, p=0.01). Additionally, Clark level I and II tumours expressed significantly lower p21 positivity than Clark level III, IV and V (p=0.006). Similarly, thick tumors showed a higher bax expression (p=0.012). Our results suggested that the role of p21 expression is more complicated in melanocytic skin cancers and abnormal regulation or abnormal function of cell cycle regulators occurred in the development and progression of malignant melanoma. In order to understand the role of bax expression in thick malignant melanomas and invasion biology, comparative analytic studies with other apoptosis regulators are needed.