Bcl-2 protooncogene expression in cervical carcinoma cell lines containing inactive p53

Nuclear Ceramide Is Associated with Ataxia Telangiectasia Mutated Activation in the Neocarzinostatin-Induced Apoptosis of Lymphoblastoid Cells

Ceramide is a bioactive sphingolipid that mediates ionizing radiation- and chemotherapy-induced apoptosis. Neocarzinostatin (NCS) is a genotoxic anti-cancer drug that induces apoptosis in response to DNA double-strand breaks (DSBs) through ataxia telangiectasia mutated (ATM) activation. However, the involvement of ceramide in NCS-evoked nuclear events such as DSB-activated ATM has not been clarified. Here, we found that nuclear ceramide increased by NCS-mediated apoptosis through the enhanced assembly of ATM and the meiotic recombination 11/double-strand break repair/Nijmengen breakage syndrome 1 (MRN) complex proteins in human lymphoblastoid L-39 cells. NCS induced an increase of ceramide production through activation of neutral sphingomyelinase (nSMase) and suppression of sphingomyelin synthase (SMS) upstream of DSB-mediated ATM activation. In ATM-deficient lymphoblastoid AT-59 cells compared with L-39 cells, NCS treatment showed a decrease of apoptosis even though ceramide increase and DSBs were observed. Expression of wild-type ATM, but not the kinase-dead mutant ATM, in AT-59 cells increased NCS-induced apoptosis despite similar ceramide accumulation. Interestingly, NCS increased ceramide content in the nucleus through nSMase activation and SMS suppression and promoted colocalization of ceramide with phosphorylated ATM and foci of MRN complex. Inhibition of ceramide generation by the overexpression of SMS suppressed NCS-induced apoptosis through the inhibition of ATM activation and assembly of the MRN complex. In addition, inhibition of ceramide increased by the nSMase inhibitor GW4869 prevented NCS-mediated activation of the ATM. Therefore, our findings suggest the involvement of the nuclear ceramide with ATM activation in NCS-mediated apoptosis. SIGNIFICANCE STATEMENT: This study demonstrates that regulation of ceramide with neutral sphingomyelinase and sphingomyelin synthase in the nucleus in double-strand break-mimetic agent neocarzinostatin (NCS)-induced apoptosis. This study also showed that ceramide increase in the nucleus plays a role in NCS-induced apoptosis through activation of the ataxia telangiectasia mutated/meiotic recombination 11/double-strand break repair/Nijmengen breakage syndrome 1 complex in human lymphoblastoid cells.

Silver Nanoparticles Surface-Modified with Carbosilane Dendrons as Carriers of Anticancer siRNA

Gene therapy is a promising approach in cancer treatment; however, current methods have a number of limitations mainly due to the difficulty in delivering therapeutic nucleic acids to their sites of action. The application of non-viral carriers based on nanomaterials aims at protecting genetic material from degradation and enabling its effective intracellular transport. We proposed the use of silver nanoparticles (AgNPs) surface-modified with carbosilane dendrons as carriers of anticancer siRNA (siBcl-xl). Using gel electrophoresis, zeta potential and hydrodynamic diameter measurements, as well as transmission electron microscopy, we characterized AgNP:siRNA complexes and demonstrated the stability of nucleic acid in complexes in the presence of RNase. Hemolytic properties of free silver nanoparticles and complexes, their effect on lymphocyte proliferation and cytotoxic activity on HeLa cells were also examined. Confocal microscopy proved the effective cellular uptake of complexes, indicating the possible use of this type of silver nanoparticles as carriers of genetic material in gene therapy.

Transcriptional Inactivation of p53, Bax, Bcl-2 and Mdm2 Correlates with Malignant Transformation of the Uterine Cervix

Deregulation of the apoptotic machinery plays a major role in cell death, cellular transformation and cancer. p53, Bcl-2, Bcl-XL, Bax and Mdm2 mRNA expression patterns were evaluated in tissue samples with cervical intraepithelial neoplasia (CIN) and cervical cancer compared to those of normal cervical tissues, and correlated with the underlying cervical lesions. Transcript levels of the above genes were assessed by RT-PCR analysis in a total of 44 cervical specimens. p53, Bcl-2, Bax and Mdm2 transcript levels were significantly different in the normal, CIN and cancer specimen groups (p=0.003, p=0.009, p=0.040 and p=0.001, respectively). Specifically, p53, Bax and Bcl-2 exhibited substantially lower transcript levels in CIN lesions compared to controls, whereas Bax mRNA levels showed a significant decrease in cancer compared to normal specimens. Mdm2 mRNA expression was considerably lower in cancer than in CIN lesions or normal cervix. High-grade squamous intraepithelial lesions exhibited lower p53 and Bcl-2 mRNA levels than controls (p=0.002, p=0.016). Coexpression analysis revealed more correlations between the above apoptosis-related molecules in normal tissues compared to CIN or cancer specimens. p53 showed significant coexpression with Bax, Bcl-2 and Mdm2 (p=0.040, p=0.013 and p=0.015, respectively) in normal cervical specimens. Bax and Bcl-XL mRNA expression was negatively correlated. Mdm2 transcriptional levels correlated significantly with those of Bax, Bcl-XL and Bcl-2. Our findings show that p53, Bax, Bcl-2 and Mdm2 mRNA expression levels correlate with the malignant transformation of the uterine cervix. mRNA coexpression patterns of the members of the pro- and anti-apoptotic family examined in cervical carcinogenesis were found to be disrupted in CIN and cancer, as already demonstrated at the protein level.

Disruption of Bcl-2 and Bcl-xL by viral proteins as a possible cause of cancer

The Bcl proteins play a critical role in apoptosis, as mutations in family members interfere with normal programmed cell death. Such events can cause cell transformation, potentially leading to cancer. Recent discoveries indicate that some viral proteins interfere with Bcl proteins either directly or indirectly; however, these data have not been systematically described. Some viruses encode proteins that reprogramme host cellular signalling pathways controlling cell differentiation, proliferation, genomic integrity, cell death, and immune system recognition. This review analyses and summarises the existing data and discusses how viral proteins interfere with normal pro- and anti-apoptotic functions of Bcl-2 and Bcl-xL. Particularly, this article focuses on how viral proteins, such as Herpesviruses, HTLV-1, HPV and HCV, block apoptosis and how accumulation of such interference predisposes cancer development. Finally, we discuss possible ways to prevent and treat cancers using a combination of traditional therapies and antiviral preparations that are effective against these viruses.

Cellular levels of oxidative stress affect the response of cervical cancer cells to chemotherapeutic agents

Treatment of advanced and relapsed cervical cancer is frequently ineffective, due in large part to chemoresistance. To examine the pathways responsible, we employed the cervical carcinoma-derived SiHa and CaSki cells as cellular models of resistance and sensitivity, respectively, to treatment with chemotherapeutic agents, doxorubicin, and cisplatin. We compared the proteomic profiles of SiHa and CaSki cells and identified pathways with the potential to contribute to the differential response. We then extended these findings by comparing the expression level of genes involved in reactive oxygen species (ROS) metabolism through the use of a RT-PCR array. The analyses demonstrated that the resistant SiHa cells expressed higher levels of antioxidant enzymes. Decreasing or increasing oxidative stress led to protection or sensitization, respectively, in both cell lines, supporting the idea that cellular levels of oxidative stress affect responsiveness to treatment. Interestingly, doxorubicin and cisplatin induced different profiles of ROS, and these differences appear to contribute to the sensitivity to treatment displayed by cervical cancer cells. Overall, our findings demonstrate that cervical cancer cells display variable profiles with respect to their redox-generating and -adaptive systems, and that these different profiles have the potential to contribute to their responses to treatments with chemotherapy.

Phase 2 trial of paclitaxel, 13-cis retinoic acid, and interferon alfa-2b in the treatment of advanced stage or recurrent cervical cancer

OBJECTIVE

Overexpression of bcl-2 is a mechanism of drug resistance in cervical cancer. Agents that down-regulate bcl-2 may decrease tumor cell threshold and sensitize tumor cells to chemotherapy. The objective of this multi-institutional phase 2 trial was to evaluate the efficacy and toxicity of paclitaxel and bcl-2 modulators (13-cis retinoic acid and interferon alfa-2b) in patients with advanced-stage or recurrent cervical cancer.

MATERIALS AND METHODS

Patients had biopsy-proven metastatic, first relapse, or persistent cervical cancer with no prior chemotherapy except for chemosensitizing agents. The treatment consisted of oral 13-cis retinoic acid, 1 mg/kg, and subcutaneous interferon alfa-2b, 6 mU/m, days 1 to 4, and intravenous paclitaxel, 175 mg/m, day 4 until disease progression or adverse events prohibited treatment. The primary endpoint was overall response rate.

RESULTS

Thirty-three patients were enrolled between March 2001 and June 2009. Thirty-one patients were eligible for evaluation of treatment response. Twenty-seven patients (82%) received prior concurrent chemoradiation or radiotherapy alone before study enrollment. The overall response rate was 30% (6 complete responses and 4 partial responses). Furthermore, 7 patients (21%) had stable disease. Grade 3 or 4 adverse events included neutropenia (n =16 [48%]), febrile neutropenia (n = 1 [3%]), and anemia (n = 1 [3%]). There were no treatment-related deaths. The median progression-free survival was 3.4 months (95% confidence interval, 2.0-7.4 months), and overall survival was 11.2 months (95% confidence interval, 7.5-26.2 months). Of 6 patients with complete responses, 5 patients survived more than 2 years.

CONCLUSIONS

Combination therapy with paclitaxel, 13-cis retinoic acid, and interferon alfa-2b is feasible and safe in treating patients with advanced and recurrent cervical cancer.

A novel anticancer therapy that simultaneously targets aberrant p53 and Notch activities in tumors

Notch signaling pathway plays an important role in tumorigenesis by maintaining the activity of self-renewal of cancer stem cells, and therefore, it is hypothesized that interference of Notch signaling may inhibit tumor formation and progression. H101 is a recombinant oncolytic adenovirus that is cytolytic in cells lacking intact p53, but it is unable to eradicate caner stem cells. In this study, we tested a new strategy of tumor gene therapy by combining a Notch1-siRNA with H101 oncolytic adenovirus. In HeLa-S3 tumor cells, the combined therapy blocked the Notch pathway and induced apoptosis in tumors that are p53-inactive. In nude mice bearing xenograft tumors derived from HeLa-S3 cells, the combination of H101/Notch1-siRNA therapies inhibited tumor growth. Moreover, Notch1-siRNA increased Hexon gene expression at both the transcriptional and the translational levels, and promoted H101 replication in tumors, thereby enhancing the oncolytic activity of H101. These data demonstrate the feasibility to combine H101 p53-targted oncolysis and anti-Notch siRNA activities as a novel anti-cancer therapy.

The anti-apoptotic protein lifeguard is expressed in breast cancer cells and tissues

Lifeguard (LFG) is an anti-apoptotic protein that inhibits Fas-mediated death in tumour cells. However, the molecular function of human LFG in the carcinogenesis of human breast cells is uncertain. We studied the expression and function of endogenous LFG in four breast cancer cell lines (MCF-7, MDA-MB-231, T-47D and HS 578T), a human breast epithelial cell line (HS 578Bst), and in healthy and cancerous breast tissues. Molecular (Western blot and RT-PCR) and immunohistochemical techniques were used to investigate the LFG expression. To investigate the breast cancer cell proliferation in the presence of Fas, we performed fluorescent cell viability assays. The possible association of Fas with LFG was analyzed by immunofluorescence microscopy. In this paper, we provide convincing evidence that LFG is overexpressed in several human breast cancer cell lines. More importantly, we found that the LFG expression correlates with high tumour grades in primary breast tumours. Finally, we demonstrated that Fas sensitivity is reduced in breast cancer cell lines expressing LFG. Our results indicated that LFG is strongly expressed in breast cancer epithelial cells. Moreover, the overexpression of LFG correlated with tumour grade and reduced Fas sensitivity. Our findings support the idea that LFG may have a role in the downregulation of apoptosis in breast cancer cells.

Enhanced therapeutic efficacy by simultaneously targeting two genetic defects in tumors

Targeting tumor-specific gene abnormalities has become an attractive approach in developing therapeutics to treat cancer. Overexpression of Bcl2 and mutations of p53 represent two of the most common molecular defects in tumors. In the nucleus, p53 induces cell cycle arrest, while it interacts with Bcl2 outside of the nucleus to regulate signal pathways involved in apoptosis. To potentiate antitumor activity, we tested a "double target" approach to antitumor therapy by combining H101, a recombinant oncolytic adenovirus that targets the inactive p53 in tumors, with a small interfering RNA (siBCL2) that targets Bcl2. In cell culture, the combined treatment significantly enhanced apoptosis and cytotoxicity as compared with treatment with either H101 or siBCL2 alone. In animals carrying tumor xenographs, combined H101 and siBCL2 treatment significantly inhibited tumor growth and prolonged survival. At the end of the study, all animals in the combined therapy group survived and two of the five animals showed complete eradication of their tumors. Interestingly, siBCL2 treatment increased H101 viral replication in both treated cells and tumor tissues. Simultaneously targeting two tumor-specific gene abnormalities using an oncolytic adenovirus and siRNA potentiates total antitumor activity.

Nuclear translocation of the pro-apoptotic Bcl-2 family member Bok induces apoptosis

The anti-apoptotic members of the Bcl-2 family, such as Bcl-2 and Bcl-XL, play a central role in preventing the induction of apoptosis via the intrinsic apoptotic pathway. It has been previously shown that induction of apoptosis by the pro-apoptotic Bcl-2 family member Bok is not antagonized by either Bcl-2 or Bcl-xL, suggesting that Bok might have a unique role in the apoptotic cascade. We showed here that human Bok is the only member of the Bcl-2 family to have a leucine-rich sequence indicative of a nuclear export signal within its BH3 domain. Western blot analysis of nuclear and cytoplasmic fractions identified Bok in both the nucleus and the cytoplasm of HEK 293T cells, HeLa cells, and breast cancer cells, and its nuclear concentration increased after treatment of those cells with leptomycin B, an inhibitor of the exportin Crm1. Immunocytochemistry of flag-tagged Bok confirmed its nuclear localization. Mutating the nuclear export signal of Bok by site-directed mutagenesis resulted in an increase in its nuclear localization and apoptotic activity. We also found that Crm1 interacted with wild-type Bok but not with the mutated form. These results suggest that nuclear export of Bok is a regulated process mediated by Crm1, and constitutes the first report of a link between the apoptotic activity and nuclear localization of a pro-apoptotic member of the Bcl-2 family.

BRCA1 Interaction with Human Papillomavirus Oncoproteins

Previously, we reported that BRCA1 strongly represses the transcriptional activity of estrogen receptor-alpha (ER-alpha) in human breast and prostate cancer cells but only weakly inhibits ER-alpha in cervical cancer cells. We now report that introduction of the human papillomavirus E7 or E6 oncogenes into human papillomavirus-negative cells rescues the BRCA1 repression of ER-alpha activity and that the E7 and E6 oncoproteins interact directly with BRCA1 in vitro and associate with BRCA1 in vivo in cultured cells. This interaction involves at least two contact points on BRCA1, one within an N-terminal site shown previously to interact with ER-alpha and the other in a C-terminal region of BRCA1 containing the first BRCA1 C-terminal domain. Point mutations within the zinc finger domains of E7 and E6 inactivated the binding to the N terminus of BRCA1 and reduced their ability to rescue BRCA1 inhibition of ER-alpha. E6 and E7 also antagonized the ability of BRCA1 to inhibit c-Myc E-box-mediated transactivation and human telomerase reverse transcriptase promoter activity, in a manner dependent upon the zinc finger domains. Finally, the ability of E6 and E7 to antagonize BRCA1 did not involve proteolytic degradation of BRCA1. These findings suggest functional interactions of BRCA1 with E7 and E6. The potential significance of these findings is discussed.

Evaluation of expression of apoptosis-related proteins and their correlation with HPV, telomerase activity, and apoptotic index in cervical cancer

OBJECTIVE

The aim of this study was to examine the expression of apoptosis-related proteins in cervical cancer, and investigate their correlation with the apoptotic index (AI), telomerase activity, human papilloma virus (HPV) infection and clinicopathological characteristics.

METHODS

Fifty cervical cancer samples and 20 normal cervical tissues were assessed for the protein expression of survivin, Bcl-2, Cox-2, p53 and p73 by immunohistochemistry. HPV DNA was detected by PCR, telomerase activity by PCR-ELISA, and AI by TUNEL assay.

RESULTS

46/50 cervical tumors (92%) showed an increased telomerase activity as compared to 3/20 (15%) controls. 45/50 (90%) cervical tumors were positive for HPV, of which 30 were HPV-16 positive and 5 were HPV-18 positive. 24/50 (48%) tumors were positive for survivin, 14 (28%) for Bcl-2, 13 (26%) for Cox-2, 19/45 (42%) for p73, 10/45 (24%) for p53. Telomerase activity was highest in tumors with the poorest grade. A positive correlation was seen between survivin and Bcl-2, survivin and tumor stage, Bcl-2 and Cox-2, p73 and p53 and p73 and the AI. Despite the overexpression of various antiapoptotic proteins, no significant difference was observed in the AI between tumors and controls.

CONCLUSIONS

Since deregulation of the apoptotic pathway appears to occur in cervical cancer, some apoptosis-related proteins could be assessed as potential markers for progression/prognosis in cervical cancer. Additionally, newer proteins such as p73 may play a compensatory role for the nonfunctional proteins such as p53.

Synthetic bile acid derivatives induce apoptosis through a c-Jun N-terminal kinase and NF-kappaB-dependent process in human cervical carcinoma cells

Recently, we have reported that a synthetic derivative of ursodeoxycholic acid (UDCA), HS-1183, and those of chenodeoxycholic acid (CDCA), HS-1199 and HS-1200, induced apoptosis in human breast carcinoma cells through a p53-independent pathway. Here, we present that the synthetic bile acid derivatives induce apoptosis in SiHa human cervical carcinoma cells as well. The parental compounds, UDCA and CDCA, exhibited no significant effect on the cell viability at the concentration ranges tested. However, their synthetic bile acid derivatives significantly decreased cell viability in a concentration dependent manner. Characteristic manifestations of apoptosis including DNA fragmentation, an increased level of proapoptotic protein Bax, and cleavage of poly(ADP-ribose) polymerase were shown when the cells were treated with these synthetic compounds. Nuclear translocation of nuclear transcription factor NF-kappaB was increased and this suggests that the synthetic compounds induce apoptosis in a NF-kappaB dependent pathway. Phosphorylations of p38 and extracellular signal-regulated kinase were not affected, whereas c-Jun N-terminal kinase (JNK) was activated along with an increased level of transcription factor c-Jun. Our studies demonstrate that the newly synthesized bile acids are capable of inhibiting cell proliferation and inducing apoptosis in SiHa cells through activation of JNK and NF-kappaB.

The adenovirus E1A and E1B19K genes provide a helper function for transfection-based adeno-associated virus vector production

Although the adenoviral E1, E2A, E4 and VA RNA regions are required for efficient adeno-associated virus (AAV) vector production, the role that the individual E1 genes (E1A, E1B19K, E1B55K and protein IX) play in AAV vector production has not been clearly determined. E1 mutants were analysed for their ability to mediate AAV vector production in HeLa or KB cells, when cotransfected with plasmids encoding all other packaging functions. Disruption of E1A and E1B19K genes resulted in vector yield reduction by up to 10- and 100-fold, respectively, relative to the wild-type E1. Interruption of the E1B55K and protein IX genes had a modest effect on vector production. Interestingly, expression of anti-apoptotic E1B19K cellular homologues such as Bcl-2 or Bcl-x(L) fully complemented E1B19K mutants for AAV vector production. These findings may be valuable for the future development of packaging cell lines for AAV vector production.

Low Frequency of bcl-2 Expression in Large Non-Polypoid Colonic Neoplasms

Large non-polypoid colorectal adenomas that spread over the mucosa and morphologically flat lesions are included in a group called granule-aggregating tumours. These are uncommon in the West. We aimed to clarify the biological differences between granule-aggregating tumours and colorectal polypoid adenomas. We evaluated the extent of apoptotic cell loss and expression of bcl-2 and p53 oncoproteins in 26 granule-aggregating tumours and 19 polypoid adenomas. The mean apoptosis index value of granule-aggregating tumours was significantly higher than that of polypoid adenomas. Only two (7.7%) granule-aggregating tumours and 13 (68.4%) polypoid colorectal adenomas expressed bcl-2, while 12 (46.2%) granule-aggregating tumours and six (31.6%) polypoid colorectal adenomas were p53-positive. Our results show that the higher apoptosis index and frequent expression of bcl-2 oncoprotein differentiates granule-aggregating tumours from polypoid colorectal adenomas. We propose that large non-polypoid granule-aggregating tumours of the colorectum are a biologically distinct entity.

Concerted regulation of inorganic pyrophosphate and osteopontin by akp2, enpp1, and ank: an integrated model of the pathogenesis of mineralization disorders

Tissue-nonspecific alkaline phosphatase (TNAP) hydrolyzes the mineralization inhibitor inorganic pyrophosphate (PP(i)). Deletion of the TNAP gene (Akp2) in mice results in hypophosphatasia characterized by elevated levels of PP(i) and poorly mineralized bones, which are rescued by deletion of nucleotide pyrophosphatase phosphodiesterase 1 (NPP1) that generates PP(i). Mice deficient in NPP1 (Enpp1(-/-)), or defective in the PP(i) channeling function of ANK (ank/ank), have decreased levels of extracellular PP(i) and are hypermineralized. Given the similarity in function between ANK and NPP1 we crossbred Akp2(-/-) mice to ank/ank mice and found a partial normalization of the mineralization phenotypes and PP(i) levels. Examination of Enpp1(-/-) and ank/ank mice revealed that Enpp1(-/-) mice have a more severe hypermineralized phenotype than ank/ank mice and that NPP1 but not ANK localizes to matrix vesicles, suggesting that failure of ANK deficiency to correct hypomineralization in Akp2(-/-) mice reflects the lack of ANK activity in the matrix vesicle compartment. We also found that the mineralization inhibitor osteopontin (OPN) was increased in Akp2(-/-), and decreased in ank/ank mice. PP(i) and OPN levels were normalized in [Akp2(-/-); Enpp1(-/-)] and [Akp2(-/-); ank/ank] mice, at both the mRNA level and in serum. Wild-type osteoblasts treated with PP(i) showed an increase in OPN, and a decrease in Enpp1 and Ank expression. Thus TNAP, NPP1, and ANK coordinately regulate PP(i) and OPN levels. The hypomineralization observed in Akp2(-/-) mice arises from the combined inhibitory effects of PP(i) and OPN. In contrast, NPP1 or ANK deficiencies cause a decrease in the PP(i) and OPN pools that leads to hypermineralization.

Co-overexpression of p53 and bcl-2 proteins in HPV-induced squamous cell carcinoma of the uterine cervix

OBJECTIVE

The aim of this study was to analyze aberrant expression of both apoptotic protein p53 and antiapoptotic protein bcl-2 in squamous cell carcinoma (SCC) of the uterine cervix with HPV infection and its significance as a marker for progression of cervical lesions.

METHODS

One hundred and five cervical lesions and 20 normal (age matched) cervical epithelium from patients with complaints other than cervical lesions were investigated immunocytochemically for aberrant expression of p53 and bcl-2 using the streptavidin-biotin-peroxidase method with respective monoclonal antibodies. HPV status was also anlayzed using type-specific primers for HPV 16/18 and HPV 6/11 by polymerase chain reaction (PCR). The statistical correlation analysis was carried out using Spearman's correlation test and univariate analysis by the SPSS system.

RESULTS

An abnormal nuclear expression of tumor-suppressor protein p53 and cytoplasmic expression of bcl-2 were observed using immunocytochemistry in biopsies of cervical lesions but not in normal subjects. The intensity of immunoreactivity for both p53 and bcl-2 proteins varied between different histopathological grades of cervical lesions and the correlation analysis showed a highly significant positive correlation for their expression level with different stages from mild dysplasia to invasive cancer with r = 0.88842; P = 0.00001 and r = 0.86929; P = 0.00001, respectively. A highly significant positive correlation was also observed between the expression of both p53 and bcl-2 proteins and HPV infection. The current study indicates a very good significant direct correlation (r = 0.83925; P = 0.00001) between p53 expression and bcl-2 expression in the study population, suggesting the co-overexpression of these proteins in HPV-associated cervical cancer.

CONCLUSIONS

From the observations it is suggested that the immunodetection of both p53 and bcl-2 proteins in squamous cell carcinoma of the uterine cervix can be used as an independent diagnostic marker for cervical cancer associated with HPV infection. The highly significant association of these proteins with HPV infection suggests that the high-risk HPV infection may be responsible for the co-overexpression of p53 and bcl-2 in cervical cancer even though both of them are antagonistic in their function. This study thus helps to understand the molecular mechanism underlying cervical carcinogenesis and which in turn may improve the therapeutic approach.

Endogenous decoy receptor 3 blocks the growth inhibition signals mediated by Fas ligand in human pancreatic adenocarcinoma

Many cancers are resistant to Fas-mediated apoptosis despite the expression of Fas. To investigate the mechanisms by which Fas signals are attenuated, we focused on decoy receptor 3 (DcR3). DcR3 is a soluble receptor against Fas ligand belonging to the tumor necrosis factor receptor superfamily and overexpresses in some forms of cancers. Exogenous DcR3 inhibits Fas-mediated apoptosis in Fas-sensitive Jurkat cells. In our study, we examined the expression and function of DcR3 in pancreatic cancers. TaqMan RT-PCR showed that DcR3 mRNA was highly expressed in pancreatic cancer cell lines (71%) and tissues (67%). Its expression significantly correlated with cancer invasion to veins. Western blotting showed that the DcR3 protein was produced and secreted in 4 of 6 cell lines. The protein expressions were compatible with the mRNA expression. Five of 7 pancreatic cancer cell lines became sensitive to agonistic anti-Fas antibody (CH-11) to various extents, without Fas upregulation, when exposed to CH-11 for 48 hr after pretreatment with IFNgamma. Four of 7 pancreatic cancer cell lines were inhibited from growing, compared to control cells, when cocultured with membrane-bounded Fas ligand (mFasL) transfected lymphomas for 48 hr after pretreatment with IFNgamma. DcR3 reduced this growth inhibition when added exogenously. Regression analysis showed that the DcR3 expression significantly correlated with the sensitivity to mFasL, and not to CH-11. These results suggest that DcR3 is highly expressed in many pancreatic cancers and endogenous DcR3 blocks the growth inhibition signals mediated by mFasL. DcR3 can be a candidate target molecule for the therapeutic intervention.

Neocarzinostatin induces an effective p53-dependent response in human papillomavirus-positive cervical cancer cells

Human papillomavirus (HPV) E6 viral oncoprotein plays an important role during cervical carcinogenesis. This oncoprotein binds the tumor suppressor protein p53, leading to its degradation via the ubiquitin-proteasome pathway. Therefore, it is generally assumed that in HPV-positive cancer cells p53 function is completely abolished. Nevertheless, recent findings suggest that p53 activity can be recovered in cells expressing endogenous E6 protein. To investigate whether p53-dependent functions controlling genome integrity, cell proliferation, and apoptosis can be reactivated in cervical cancer cells, we examined the capacity of HeLa, INBL, CaSki, C33A, and ViBo cell lines to respond to neocarzinostatin (NCS), a natural product which induces single- and double-strand breaks in DNA. We found that NCS treatment inhibits cellular proliferation through G2 cell cycle arrest and apoptosis induction. This effect was preceded by nuclear accumulation of p53 protein and by an increase of p21 transcripts. Although apoptosis was blocked in ViBo cells (HPV-negative), nuclear accumulation of transcriptionally active p53 and inhibition of cell proliferation are observed after NCS treatment. These results suggest that HPV-positive cervical cancer cells are capable of responding efficiently to DNA damage provoked by NCS treatment through a p53-dependent pathway in spite of the presence of E6 protein.

Hypoxia-inducible erythropoietin signaling in squamous dysplasia and squamous cell carcinoma of the uterine cervix and its potential role in cervical carcinogenesis and tumor progression

Tissue hypoxia is a characteristic property of cervical cancers that makes tumors resistant to chemo- and radiation therapy. Erythropoietin (Epo) is a hypoxia-inducible stimulator of erythropoiesis. Acting via its receptor (EpoR), Epo up-regulates bcl-2 and inhibits apoptosis of erythroid cells and rescues neurons from hypoxic damage. In addition to human papillomavirus infection, increased bcl-2 expression and decreased apoptosis are thought to play a role in the progression of cervical neoplasia. Using reverse transcriptase-polymerase chain reaction and Western blotting we showed that HeLa and SiHa cervical carcinoma cells and human cervical carcinomas express EpoR, and that hypoxia enhances EpoR expression. Exogenous Epo stimulated tyrosine phosphorylation and inhibited the cytotoxic effect of cisplatin in HeLa cervical carcinoma cells. Using immunohistochemistry, we examined the expression of Epo, EpoR, p16, hypoxia-inducible factor (HIF)-1alpha, and bcl-2 in benign and dysplastic cervical squamous epithelia and invasive squamous cell carcinomas (ISCCs). EpoR expression in benign epithelia was confined to the basal cell layers, whereas in dysplasias it increasingly appeared in more superficial cell layers and showed a significant correlation with severity of dysplasia. Diffuse EpoR expression was found in all ISCCs. Expression of Epo and HIF-1alpha was increased in dysplasias compared to benign epithelia. Focal Epo and HIF-1alpha expression was seen near necrotic areas in ISCCs, and showed correlation in their spatial distribution. Significant correlation was found between expression of EpoR, and p16 and bcl-2 in benign and dysplastic squamous epithelia. Our results suggest that increased expression of Epo and EpoR may play a significant role in cervical carcinogenesis and tumor progression. Hypoxia-inducible Epo signaling may play a significant role in the aggressive behavior and treatment resistance of hypoxic cervical cancers.

Evaluation of p53 and Bcl-2 expression as prognostic markers in invasive cervical carcinoma stage IIb/III patients treated by radiotherapy

OBJECTIVE

The objective was to evaluate the immunohistochemical expression of p53 and Bcl-2 proteins as prognostic markers in locally advanced [FIGO Stage IIb/III] invasive squamous cell carcinoma of the uterine cervix. It was also our aim to determine if they had any relationship to each other and to the pretreatment levels of apoptosis determined morphologically.

METHODS

Seventy-six consecutive cases of invasive squamous cell carcinoma of the cervix diagnosed in 1995 were analyzed retrospectively for the apoptotic index and p53 and Bcl-2 expression determined immunohistochemically and correlated to the patient outcome at the end of a 5-year follow-up period.

RESULTS

The overall cumulative 5-year survival was 52.63%. p53 immunoreactivity was seen in 53.9% cases with variable levels of expression. By univariate analysis, p53 positivity correlated with poor survival [chi-square P = 0.029; log-rank test P = 0.0468] but not upon multivariate analysis. The apoptotic index which ranged from 0 to 40 and Bcl-2 expression seen in 38.1% cases showed no correlation to survival. Neither p53 nor Bcl-2 expression correlated with the apoptotic index or with each other. Seven cases with the immunophenotype p53-/Bcl-2+ had an excellent survival.

CONCLUSIONS

Neither p53 nor Bcl-2 expression are independent predictors of prognosis in locally advanced cervical squamous cancers. However, evaluation of their combined expression may affect clinical outcome and needs further investigation.

Immunohistochemical expression of p53, bcl-2, and p21(WAF1/CIP1) in early cervical carcinoma: correlation with clinical outcome

The objective of this study was to assess the value of p53, bcl-2, and p21(WAF1/CIP1) immunoreactivity as predictors of pelvic lymph node metastases (LNM), recurrences, and death due to the disease in early stage (FIGO I-II) cervical carcinomas. FIGO stage, type of histopathology, and tumor grade were also evaluated in this series of patients treated by radical hysterectomy (Wertheim-Meigs) between 1965 and 1990. A total of 172 patients were included. A tumor was regarded as positive when more than 30% of the neoplastic cells exhibited immunoreactivity. Positive immunostaining was found in 8.9% for p53, in 43.5% for bcl-2, and in 25.0% for p21(WAF1/CIP1). None of them was able to predict LNM or clinical outcome. Presence of LNM, tumor recurrence, and death from disease were significantly associated with the FIGO stage (P = 0.014, P = 0.009, and P = 0.001, respectively). The 5-year cancer-specific survival rate was 91.6% and the overall survival rate was 90.5%. It was concluded that immunohistochemically detected p53, bcl-2, and p21(WAF1/CIP1) appeared to be of no predictive value with regard to LNM, tumor recurrences, or long-term survival in early cervical carcinomas.

Arsenite disrupts mitosis and induces apoptosis in SV40-transformed human skin fibroblasts

Chronic ingestion of arsenite-contaminated drinking water causes skin, bladder, and liver cancer. The mechanism of arsenite-induced carcinogenesis is unknown. Arsenite is known to disrupt mitosis and to delay transit through M phase in normal diploid fibroblasts. SV40-transformed human fibroblasts were observed to be hypersensitive to the cytotoxic and cytostatic effects of NaAsO(2) compared with normal diploid fibroblasts in concentration-response experiments. Five to 20 microM NaAsO(2) induced cytostasis in cycling normal diploid fibroblasts but not overt lethality in quiescent normal diploid fibroblasts. High concentrations of arsenite were overtly lethal in both cycling and quiescent cells. The IC50 for cycling SV40-transformed fibroblasts was 3.8 and 4.8 microM for the SV40-transformed lines GM4429 and GM0637, respectively, whereas, in cycling normal diploid fibroblasts (GM0024), the IC50 was 24.7 microM. Microscopic examination of NaAsO(2)-treated SV40-transformed fibroblasts suggested a concentration-dependent accumulation of cells in mitosis undergoing apoptosis. Treatment of SV40-transformed fibroblasts with 0-10 microM NaAsO(2) caused a concentration-dependent inhibition of cell proliferation, accumulation of cells having G2/M DNA contents, and increases in the mitotic index. Phase microscopy, annexin V binding, and electron microscopy demonstrated that arrested mitotic cells underwent apoptosis. These results indicate that SV40-transformation sensitizes cells to arsenite-induced mitotic arrest and induction of apoptosis in the mitotic cells.

Evidence of an association between human papillomavirus and impaired chemotherapy-induced apoptosis in cervical cancer cells

OBJECTIVES

The aim of this study was to determine cervical cancer cell sensitivity to chemotherapy-induced apoptosis based on human papillomavirus (HPV) status.

METHODS

CaSki (HPV-positive) and C33A (HPV-negative) cells were treated with camptothecin or cisplatin. Cellular viability was determined by trypan blue exclusion. Apoptotic indexes were determined by flow cytometric analysis of annexin V labeling and morphological changes. Mitochondrial release of cytochrome c was determined by immunofluorescence using confocal microscopy. Caspase 3 activation and bax expression were assessed by immunoblotting.

RESULTS

CaSki cells displayed chemoresistance to both camptothecin and cisplatin. Low response to apoptogenic stimuli was evidenced by a marginal increase in the apoptotic cell fraction after camptothecin treatment (22.9 +/- 2.56%) compared with control (17.8 +/- 1.95%). Cisplatin (14.8 +/- 1.01%) caused a slight decrease in apoptosis. Mitochondrial release of cytochrome c and cleavage of caspase 3 could not be demonstrated in CaSki cells after treatment. Despite p53 mutation, C33A cells were sensitive to the antiproliferative effects of camptothecin and cisplatin. Mean apoptotic events were 17.5 +/- 0.33 for control, 42 +/- 1.76 for cisplatin, and 38.1 +/- 0.75 for camptothecin. An intact cytochrome c pathway was demonstrated in C33A cells leading to cleavage of caspase 3 after camptothecin treatment. The constitutive bax expression demonstrated in both cell lines displayed no change after camptothecin treatment.

CONCLUSION

HPV-positive cervical cancer cells have an inherent resistance to chemotherapy-induced apoptosis. HPV-dependant inactivation of apoptotic regulators such as p53 and blockage of downstream events such as cytochrome c release and caspase 3 activation might be elemental to this cellular survival advantage provided by high-risk oncogenic papillomavirus.

MUC4 expression is increased in dysplastic cervical disorders

The female uterine cervix has 2 characteristic populations of epithelial cells: the endocervix is composed by mucus-secreting cells that express several mucin genes, and the exocervix has a typical stratified squamous epithelium and does not express secreted mucins. Among human mucin genes, the MUC4 sequence has a transmembrane domain, and its molecular structure suggests that it has a protective role and also may be implicated in intracellular signalling. The aim of this study is to analyze whether changes in the expression of MUC4 can be detected associated with the squamous dysplastic transformation of exocervical epithelium. MUC4 expression has been analyzed by immunohistochemistry, Western blotting, and in situ hybridization. Using immunohistochemical techniques, MUC4 is found in normal endocervix (n = 11) and is absent or only focally detected in the normal stratified cervical epithelium (n = 18). In samples from squamous metaplasia (n = 9), MUC4 is variably expressed (10% to 50% positive cells), whereas MUC4 is strongly detected in dysplastic cervical epithelia. The greatest number of positive cells is found in samples with moderate and severe dysplasia in which MUC4 is detected in 100% of the analyzed samples (n = 16). These results have been confirmed by Western blotting and by detection of MUC4 transcripts using in situ hybridization. The present data suggest that MUC4 is activated during the process of squamous dysplastic transformation and may be used as a marker for this pathologic process.

Marijuana smoke and Delta(9)-tetrahydrocannabinol promote necrotic cell death but inhibit Fas-mediated apoptosis

Marijuana smoke shares many components in common with tobacco smoke except for the presence of Delta(9)-tetrahydrocannabinol (Delta(9)-THC), the psychotropic compound found only in Cannibis sativa. Delta(9)-THC has been shown to potentiate smoke-induced oxidative stress and necrotic cell death. In the present study, our objective was to determine the effects of Delta(9)-THC on the balance between Fas-induced apoptosis and necrosis in A549 lung tumor cells. We found that Fas-induced activation of caspase-3 was inhibited by whole smoke from both tobacco and marijuana cigarettes. Gas-phase smoke, which generates high levels of intracellular reactive oxygen species, had no effect on caspase-3 activity. However, particulate-phase smoke (tar) was a potent inhibitor of Fas-induced caspase-3 activity, with marijuana tar being more potent than either tobacco or placebo marijuana tar (lacking Delta(9)-THC). Delta(9)-THC also inhibited Fas-induced caspase-3 activity in A549 cells. In contrast, no inhibition was observed when Delta(9)-THC was incubated with activated caspase-3 enzyme, suggesting that Delta(9)-THC acts on the cell pathway(s) leading to caspase-3 activation and not directly on enzyme function. Flow cytometry was used to measure the percentage of cells undergoing apoptosis (staining for annexin V) versus necrosis (staining for propidium iodide) and confirmed that both marijuana tar extract and synthetic Delta(9)-THC inhibit Fas-induced apoptosis while promoting necrosis. These observations suggest that the Delta(9)-THC contained in marijuana smoke disrupts elements of the apoptotic pathway, thereby shifting the balance between apoptotic and necrotic cell death. This shift may affect both the carcinogenic and immunologic consequences of marijuana smoke exposure.

The importance of biological factors (bcl-2, bax, p53, PCNA, MI, HPV and angiogenesis) in invasive cervical cancer

OBJECTIVE

The present study was designed to analyse the relationship between apoptosis related proteins (bcl-2 and bax), tumour suppressor protein p53, proliferation markers (PCNA and mitotic index), human papillomavirus (HPV) and angiogenesis in cervical cancer and their impact on clinical outcome.

STUDY DESIGN

Tumours from 111 patients were assessed by immunohistochemistry for the expression of bcl-2, bax, p53 and PCNA, by PCR for the presence of HPV-DNA, for the quantification of the mitotic index and the microvessel density (CD 31). The results were correlated with various histopathologic characteristics and survival.

RESULTS

The multiple Cox's regression analysis for overall survival of all prognostic variables gave as best model: bcl-2 (P<0.001), lymphovascular permeation (P=0.004), mitotic index (P=0.019), tumour grade (P=0.048) and FIGO stage (P=0.070). Subanalysis was performed for the patients where the lymph node status was known (n=79). Adding the lymph node status gave as best model for overall survival bcl-2 (P=0.001), lymphovascular permeation (P=0.003) and mitotic index (P=0.044). However, they hardly influenced the association.

CONCLUSION

In the apoptotic pathway of cervical cancer, bcl-2 is one of most important proteins. It can probably not only mediate cell death but also regulate cell growth. A better understanding of their relations will probably provide the basis for more rational cancer therapies in the future.

Ability to undergo apoptosis does not correlate with the intrinsic radiosensitivity (SF2) of human cervix tumor cell lines

PURPOSE

To investigate the relationship between radiation-induced apoptosis and clonogenic cell kill in 9 cervical cancer cell lines.

METHODS AND MATERIALS

Cells were irradiated with 0, 2, 8, and 30 Gy. The level of apoptosis was evaluated using flow cytometry (Annexin-V binding), light microscropy (morphology), gel electrophoresis (DNA ladder formation), and TUNEL assay. Cell survival was measured using a clonogenic assay.

RESULTS

Of the 9 cervical carcinoma cell lines analyzed, 3 underwent radiation-induced apoptosis: CaSki, HT3, and 778. The levels of apoptosis, obtained 72 h after a dose of 30 Gy, were 49%, 28%, and 26%, respectively. All cell lines exhibited some level of background apoptosis measured by Annexin-V binding (mean = 2.6%+/-0.8; range, 0.2-6.9%) that correlated with the level of radiation-induced apoptosis (r = 0.92, p = 0.001). In 6 of the 9 lines, necrosis was the dominant form of cell death. A significant inverse relationship was found between the level of radiation-induced apoptosis and necrosis after 30 Gy (r = -0.87, p = 0.002). No relationship was found between radiation-induced apoptosis and intrinsic radiosensitivity measured, using a clonogenic assay, as surviving fraction at 2 Gy (SF2).

CONCLUSION

Cervical carcinoma cells do not readily undergo radiation-induced apoptosis in vitro. There is no relationship between ability to undergo apoptosis and intrinsic radiosensitivity measured using a clonogenic assay.

Prostate Cancer - Old Problems and New Approaches. (Part II. Diagnostic and Prognostic Markers, Pathology and Biological Aspects)

Diagnostic and prognostic markers for prostatic cancer (PCa) include conventional protein markers (e.g., PAP, PSA, PSMA, PIP, OA-519, Ki-67, PCNA, TF, collagenase, and TIMP 1), angiogenesis indicator (e.g., factor VIII), neuroendocrine differentiation status, adhesion molecules (E-cadherin, integrin), bone matrix degrading products (e.g., ICPT), as well as molecular markers (e.g., PSA, PSMA, p53, 12-LOX, and MSI). Currently, only PSA is used clinically for early diagnosis and monitoring of PCa. The histological differential diagnosis of prostatic adenocarcinoma includes normal tissues such as Cowper's gland, paraganglion tissue and seminal vesicle or ejaculatory duct as well as pathological conditions such as atypical adenomatous hyperplasia, atrophy, basal cell hyperplasia and sclerosing adenosis. A common PCa is characterized by a remarkable heterogeneity in terms of its differentiation, microscopic growth patterns and biological aggressiveness. Most PCa are multifocal with signi ficant variations in tumor grade between anatomically separated tumor foci. The Gleason grading system which recognizes five major grades defined by patterns of neoplastic growth has gained almost uniform acceptance. In predicting the biologic behavior of PCa clinical and pathological stages are used as the major prognostic indicators. Among the cell proliferation and death regulators androgens are critical survival factors for normal prostate epithelial cells as well as for the androgen-dependent human prostatic cancer cells. The androgen ablation has been shown to increase the apoptotic index in prostatic cancer patients and castration also promotes apoptotic death of human prostate carcinoma grown in mice. The progression of PCa, similarly to other malignancies, is a multistep process, accompanied by genetic and epigenetic changes, involving phenomenons as adhesion, invasion and angiogenesis (without prostate specific features).

Prolonged survival of heart allografts from p53-deficient mice

BACKGROUND

Acute rejection of the heart allograft is the major cause of heart failure in the first month after transplantation. Most studies on the prevention of acute rejection have concentrated on immune suppression of the recipients, whereas little is known about the effects of genetically manipulated donor organs on heart allograft survival. Herein, we describe a mouse model of heart allografts donated by p53-/- mice that can prolong the survival time of the grafts.

METHODS

Hearts of p53-/- or p53+/+ C57BL/6J mice were grafted to the neck carotid artery and jugular vein of BALB/c mice using a cuff technique. The graft survival was observed daily. The hearts were analyzed using several techniques, including histology, immunofluorescence, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL), and Western blot analysis.

RESULTS

p53+/+ allografts ceased beating at 7.6+/-0.5 days, whereas p53-/- hearts were beating at 10.5+/-1.1 days after transplantation (P<0.01). Mean histological rejection scores were significantly lower in allografts donated by p53-deficient mice. Furthermore, apoptotic cells, determined by TUNEL and a reagent kit for detection of cardiac apoptosis, were of high numbers in the allograft sections from wild-type hearts but rare in p53-/- allografts (4.2+/-1.3 vs. 0.7+/-0.5/250x field). Immunofluorescence staining and Western blot analysis revealed that high levels of p53 and proapoptotic protein Bax were expressed in wild-type grafts but not p53-/- allografts. Interestingly, Bcl-2, an antiapoptotic protein, was abundant in cardiac allografts from p53-/- mice and almost undetectable in grafts from wild-type mice.

CONCLUSIONS

Thus, p53 is involved in cardiac apoptosis induced by alloimmune reaction, and prolonged survival of heart allografts can be achieved when p53 is lacking.

Prognostic significance of Bcl-2 in Wilms' tumor and oncogenic potential of Bcl-X(L) in rare tumor cases

Anaplastic Wilms' tumors are commonly believed to be rare forms of progression, driven by p53 mutations, of the more common classical Wilms' tumor or nephroblastoma Contrary to classical Wilms' tumors, anaplastic tumors traditionally tend to metastasize, to be drug-resistant and to have a poor prognosis. The Bcl-2 gene product protects cells from programmed cell death, and its over-expression has been proposed to be tumorigenic and to mediate resistance to therapy. Because Bcl-2 has been reported to be transcriptionally repressed by p53, using immuno-histochemistry and mRNA analyses, we have examined Bcl-2 expression in a panel of 10 classical and 3 anaplastic nephroblastomas in which the p53 status had been previously analyzed. We found that classical Wilms' tumors expressed significant amounts of Bcl-2 mRNA and protein, whereas anaplastic tumors did not, regardless of p53 mutations. However, because mortality occurred both among patients with classical and among those with anaplastic tumors, which had divergent Bcl-2 expression, analysis of variance failed to demonstrate prognostic Bcl-2 significance. Therefore, we examined the expression of the Bcl-X and Bax genes, which are known to synergize and antagonize Bcl-2, respectively. With the exception of anaplastic tumor W17, the monotony of Bcl-X and Bax mRNA levels did not suggest that the expression of these apoptosis-regulating genes could have a role in the prognosis of nephroblastoma. In addition to the standard 2.7-kb Bcl-X(L) mRNA, W17 expressed a 3.5-kb mRNA species which had the same coding capacity for Bcl-X(L) as the 2.7-kb mRNA. Western analysis demonstrated that W17 had the highest level of Bcl-X(L) protein, suggesting that Bcl-X(L) over-expression could play a part in the development of anaplasia in rare Wilms' tumor cases without affecting prognosis.

Overexpression of anti-apoptotic gene BAG-1 in human cervical cancer

Apoptosis is a programmed cell death process in which cells commit suicide under certain environmental conditions. Recent studies suggest that apoptosis is controlled by a variety of cellular genes, and dysregulation of these genes plays an important role in the pathogenesis of human diseases, including cancer. BAG-1 is a novel anti-apoptotic protein isolated by its interaction with another anti-apoptotic protein, Bcl-2. It binds to several hormone receptors and growth factor receptors and modulates their function in apoptosis. However, the role of BAG-1 in the oncogenesis of human cervical cancer has yet to be illustrated. In this study, we examined the expression of BAG-1 in cervical normal and carcinoma cultured cells and tissues. BAG-1 was overexpressed in human cervical carcinoma cell lines and tissues. Overexpression was regulated at the transcriptional level. The increased expression of BAG-1 was correlated with enhanced resistance of cervical carcinoma cells to apoptosis induced by a DNA-damaging reagent. In addition, overexpression of BAG-1 enhanced the resistance of cervical cells to apoptosis. This study provided the first evidence that BAG-1 is upregulated in human cervical cancer and may play an important role in apoptosis and human cervical carcinogenesis.

Sendai virus infection induces apoptosis through activation of caspase-8 (FLICE) and caspase-3 (CPP32)

Sendai virus (SV) infection and replication lead to a strong cytopathic effect with subsequent death of host cells. We now show that SV infection triggers an apoptotic program in target cells. Incubation of infected cells with the peptide inhibitor z-VAD-fmk abrogated SV-induced apoptosis, indicating that proteases of the caspase family were involved. Moreover, proteolytic activation of two distinct caspases, CPP32/caspase-3 and, as shown for the first time in virus-infected cells, FLICE/caspase-8, could be detected. So far, activation of FLICE/caspase-8 has been described in apoptosis triggered by death receptors, including CD95 and tumor necrosis factor (TNF)-R1. In contrast, we could show that SV-induced apoptosis did not require TNF or CD95 ligand. We further found that apoptosis of infected cells did not influence the maturation and budding of SV progeny. In conclusion, SV-induced cell injury is mediated by CD95- and TNF-R1-independent activation of caspases, leading to the death of host cells without impairment of the viral life cycle.

Increase in the fraction of necrotic, not apoptotic, cells in SiHa xenograft tumours shortly after irradiation

BACKGROUND AND PURPOSE

Approximately 18% of the cells recovered by rapid mechanical dissociation of SiHa xenograft tumours contain large numbers of DNA strand breaks. The number of damaged cells increases to 30-40% 4-6 h after exposure to 5 or 15 Gy, returning to normal levels by 12 h. This observation is reminiscent of the rate of production of apoptotic cells in other murine and human xenograft tumours. The nature of this damage, rate of development and relation to cell proliferation rate were therefore examined in detail.

MATERIALS AND METHODS

SiHa human cervical carcinoma cells were grown as xenograft tumours in SCID mice. Single-cell suspensions were prepared as a function of time after irradiation of the mouse and examined for DNA damage using the alkaline comet assay. Cell cycle progression was measured by flow cytometry evaluation of anti-bromodeoxyuridine-labelled tumour cells.

RESULTS

Significant numbers of apoptotic cells could not be detected in irradiated SiHa tumours using an end-labelling assay, electron microscopy, or histological examination of thin sections. Instead, xenograft cells exhibiting extensive DNA damage in the comet assay were predominantly necrotic cells. The increase in the proportion of heavily damaged cells 4-6 h after irradiation could be the result of an interplay between several factors including loss of viable cells and change in production or loss of necrotic cells. Analysis of the progression of BrdUrd-labelled cells confirmed that while 35% of cells from untreated SiHa tumours had divided and entered G1 phase by 6 h after BrdUrd injection, none of the labelled cells from tumours exposed to 5 or 15 Gy had progressed to G1.

CONCLUSIONS

The increase in the percentage of SiHa tumour cells with extensive DNA damage 4-6 h after irradiation is attributable to necrosis, not apoptosis. Cell cycle progression and cell loss are likely to influence the kinetics of appearance of both apoptotic and necrotic cells in irradiated tumours.

Antiproliferative activity of interferon alpha and retinoic acid in SiHa carcinoma cells: the role of cell adhesion

Several lines of evidence have demonstrated that IFNs could be relevant in the treatment of certain neoplastic diseases such as carcinomas. In particular, IFN-alpha, in addition to the anti-proliferative and cytostatic effects, was demonstrated to be capable of inducing cell death by apoptosis both in vivo and in vitro. Numerous protocols have also been proposed which consider the association of IFN-alpha with other drugs. Among these are retinoids, a class of compounds capable of inducing inhibition of cell growth and differentiation. We address the question here by analyzing the role of cell adhesion in susceptibility to IFN-alpha, RA and their combination of a human cell line derived from a squamous carcinoma of the cervix, the Bcl-2-negative SiHa cell line. In this context, cytoskeleton components and several surface molecules playing a role in cell substrate and cell-to-cell relationships have been evaluated. We found that RA treatment is capable of improving stress fiber formation, decreasing cell detachment and increasing cell-adhesion capability. However, no variations in the ability to adhere to specific extracellular-matrix molecules were found in RA-treated cells. No quantitative changes were detected in integrins involved as receptors for extracellular matrix molecules (VLAI-VLA5) or in other cell-adhesion-associated molecules (e.g., CD44). By contrast, 2 important molecules involved in cell-adhesion processes appeared to be up-regulated by RA exposure: focal adhesion kinase and E-cadherin, involved in adhesion plaque formation and cell-to-cell contacts, respectively. Keeping in mind the importance of adhesion properties in the cell-growth pathway, our findings could be of interest in the study of carcinoma-cell proliferation and metastatic potential.

Expression of bcl-2 in invasive and in situ carcinoma of the uterine cervix

OBJECTIVE

The oncoprotein bcl-2 inhibits apoptosis. The purpose of this study was to assess the expression of bcl-2 in human cervical carcinoma and to correlate this with clinicopathologic parameters.

STUDY DESIGN

Immunohistochemical staining for bcl-2 protein (MoAB clone 124) was performed on operative tissue specimens from 22 patients with carcinoma in situ of the cervix and from 137 patients with invasive cervical carcinoma (International Federation of Gynecology and Obstetrics stages I to IV). The immunoreactivity of bcl-2 was scored as positive (> or = 5% staining cells) or negative (< 5% staining cells).

RESULTS

Eighty-two percent of in situ carcinomas and 61% of invasive cervical carcinomas were bcl-2 positive. Expression of bcl-2 was correlated to tumor stage (p < 0.001) and to presence of vascular (p < 0.005) or lymphatic tumor (p < 0.023) permeation. In univariate analysis there was a strong relationship between bcl-2 expression and overall survival (p < 0.001). In multivariate analysis bcl-2 expression (p < 0.001), International Federation of Gynecology and Obstetrics stage (p = 0.011), and presence of lymphatic permeation (p = 0.014) proved to be independent prognostic factors.

CONCLUSIONS

Expression of bcl-2 is lost during tumor progression and is a strong prognostic parameter, suggesting that the regulation of apoptosis plays an important role in the behavior of cervical carcinomas. Better understanding of the mechanisms involved may lead to improved medical treatment strategies.

Subcellular localization of Bcl-2 protein in synovial sarcoma

The subcellular localization of Bcl-2 protein in surgically resected, fixed-frozen tissue specimens of seven tumors from six cases of synovial sarcoma and a synovial sarcoma cell line was examined using laser-scanning confocal microscopy and immunoelectron microscopy. Bcl-2 protein in synovial sarcoma cells was detected in the nuclear envelope, endoplasmic reticulum membrane, and mitochondrial circumference. Based on the finding of pre-embedding immunoelectron-microscopy observation, the distribution of Bcl-2 protein in such membranous organella was patchy. A computer-based image analysis failed to reveal any quantitative differences between the inner and the outer mitochondrial membranes. The tumorigenesis of synovial sarcoma is also discussed from the viewpoint of Bcl-2 overexpression.

Establishment and characterization of a new synovial sarcoma cell line, SN-SY-1: special reference to bcl-2 protein and SYT-SSX1 hybrid transcripts

We established and characterized a new human synovial sarcoma cell line, SN-SY-1, derived from a monophasic fibrous synovial sarcoma excised from the abdominal wall of a 21-year-old man. We maintained the cell line for over 35 passages in vitro. The SN-SY-1 cells in vitro exhibit spindle and polygonal shapes and join to form an epithelial plaque. SN-SY-1 maintained a consistent karyotype: 46,t(X;18)(p11.2;q11.2), Y, t(6;8) (q13-15;q11-13), the same as that of the primary tumor specimen. RT-PCR assay for chimeric SYT-SSX transcripts followed by digestion with restriction enzymes revealed SYT-SSX1 fusion protein. An immunohistochemical study revealed expression of bcl-2 protein in the SN-SY-1 cell line, in vitro and in vivo. However, DNA analysis showed no rearrangement of the bcl-2 gene, and expression of bcl-2 mRNA was low. Why bcl-2 protein was expressed in this synovial sarcoma was not clarified.

Target to apoptosis: a hopeful weapon for prostate cancer

BACKGROUND

Prostate cancer is the most commonly diagnosed neoplasm and the second leading cause of male death in this country. Multiple genetic and epigenetic factors have been implicated in the oncogenesis and progression of prostate cancer. However, the molecular mechanisms underlying the disease remain largely unknown. The major difficulty in the clinical management of prostate cancer stems from the reality that reliable and accurate diagnostic/prognostic biomarkers are not available and that effective treatment regimens for hormone-resistant prostate cancers are yet to be developed.

METHODS

The present review, through extensive literature research, summarizes the most recently accumulated experimental and clinical data on the relationship between apoptosis and prostate cancer. We analyze the possibility of inducing prostate cancer cell apoptosis by: 1) androgen ablation by castration or biochemical antagonists: 2) chemotherapeutic drugs or natural/synthetic chemicals; 3) manipulation of apoptosis-related oncoproteins; and 4) modulation of intracellular signal transducers.

RESULTS

1) Prostate cancer, like most other solid tumors, represents a very heterogeneous entity. Most prostate cancers, at the time of clinical diagnosis, present themselves as mixtures of androgen-dependent and androgen-independent cells. 2) Most prostate cancers respond initially to androgen ablation since the population of androgen-dependent cells undergoes rapid apoptosis upon androgen withdrawal. However, androgen ablation rarely cures patients, most of whom will experience recurrence due to takeover of the tumor mass by androgen-independent tumor cells as well as the emergence of apoptosis-resistant clones as a result of further genetic alterations such as bcl-2 amplification. 3) On the other hand, although androgen-independent prostate cancer cells do not undergo apoptosis upon androgen blocking, they do maintain the appropriate molecular machinery of apoptosis. Therefore, certain conventional chemotherapy drugs can eliminate androgen-independent cancer cells by inducing apoptosis. 4) However, most drugs used in chemotherapy induce apoptosis or mediate cytotoxicity only in proliferating cancer cells. Human prostate cancer cells demonstrate very slow growth kinetics. Thus, novel chemical/natural products need be identified to eradicate those nonproliferating cancer cells. In this regard, the angiogenesis inhibitor, linomide, and a plant extract, beta-lapachone, demonstrate very promising apoptosis-inducing effects on prostate cancer cells in a proliferation-independent manner. 5) An alternative way to modulate the apoptotic response is by interfering with the expression levels of essential regulatory molecule of apoptosis. Bcl-2 and p53 represent two prime targets for such manipulations. 6) Finally, modulation of signal transduction pathways (e.g., intracellular Ca2+ levels, PKC activity) involved in apoptosis may also induce and/or enhance the apoptotic response of prostate cancer cells.

CONCLUSIONS

Modulation of apoptotic response represents a novel mechanism-based approach which may help identify novel drugs and/or develop new therapeutic regimens for the treatment of prostate cancers.

Human papillomavirus (HPV) 16 E6 sensitizes cells to atractyloside-induced apoptosis: role of p53, ICE-like proteases and the mitochondrial permeability transition

Infection of cervical epithelial cells with certain high risk HPV genotypes is thought to play an etiologic role in the development of cervical cancer. In particular, HPV type 16 and 18 early protein 6 (E6) is thought to contribute to epithelial transformation by binding to the tumor suppressor protein p53, targeting it for rapid proteolysis, resulting in loss of its cell cycle arrest and apoptosis-inducing activities. Recent data indicate that factors responsible for triggering apoptosis reside in the cytoplasm of cells, and not in the nucleus. In particular, the findings that mitochondria are required in certain cell-free models for induction of apoptosis and that bcl-2 is localized to mitochondria have focused attention on the role of the mitochondrial membrane permeability transition (MPT) in apoptosis. Here we present data to indicate that HPV 16 E6 expression sensitizes cells to MPT-induced apoptosis. We also report that HPV 16 E6 sensitization of cells to MPT-induced apoptosis occurs only in the presence of wildtype (wt) p53 expression. The extent of apoptosis induced by atractyloside (an inducer of the MPT) in normal, temperature-sensitive (ts) p53, and HPV-16 E6 transfected J2-3T3 cells, and the HPV expressing cervical carcinoma cell lines SiHa, Hela and CaSki was determined. C33A cells, which express mutant p53 but not HPV, were also exposed to atractyloside in the presence or absence of HPV 16 E6 expression. Dose-dependent apoptosis induced by atractyloside in normal J2-3T3 cells and cervical carcinoma cells was measured by loss of cell viability, nuclear fragmentation and DNA laddering. The sensitivity of cells to atractyloside-induced apoptosis was found to be: HPV 16 E6-J2-3T3 > CaSki > normal-J2-3T3 cells approximately ts p53-J2-3T3 approximately vector-J2-3T3 cells > Hela > SiHa > C33A approximately C33A 16 E6. Cyclosporin A (CsA), an inhibitor of the MPT, and ICE-I, a protease inhibitor, provided protection against atractyloside-induced apoptosis. These findings indicate that: 1) high risk HPV 16 E6 protein is capable of sensitizing cells to apoptosis; 2) HPV 16 E6 sensitization of cells to atractyloside-induced apoptosis occurs in a p53-dependent fashion; 3) the target of HPV 16 E6 sensitization of cells to atractyloside-induced apoptosis is the mitochondria; and 4) HPV 16 E6 sensitization of cells to atroctycoside-induced apoptosis involves an ICE-like protease-sensitive mechanism, regulating the onset of the MPT. These findings constitute the first evidence that mitochondria play a role in HPV 16 E6 modulation of apoptosis.

Introduction of p21(Waf1/Cip1) gene into a carcinoma cell line of the uterine cervix with inactivated p53

In carcinomas of the uterine cervix of which p53 is frequently inactivated by papilloma viruses, gene transfer of p21, effector of p53, is an alternative tool to suppress cell growth. We introduced the p21 gene into HeLa cells. The transfectant with p21 showed a significant growth retardation by blockage of G1 to S transfer of the cell cycle. This cell line showed significantly reduced anchorage-independent growth as well as attenuated telomerase activity. These data suggest that gene transfer of p21 is an effective tool to lead carcinoma cells with inactivated p53 into less malignant phenotype.

Prognostic value of bcl-2 expression in patients with operable carcinoma of the uterine cervix

AIM

To evaluate the patterns of bcl-2 expression in early stage cervical carcinoma; to compare bcl-2 expression with clinicopathological findings; and to assess its prognostic value.

METHODS

Wertheim radical hysterectomy specimens from 76 patients (FIGO stages Ia-IIb) with untreated nonmetastatic invasive cervical carcinoma were studied. Expression of bcl-2 was detected immunohistochemically using a monoclonal antibody. A tumour was regarded as positive when more than 5% of the neoplastic cells exhibited bcl-2 immunoreactivity.

RESULTS

Forty eight (63%) cervical carcinomas were scored as bcl-2 positive and 28 (37%) as bcl-2 negative. Most tumours showed heterogeneous cytoplasmic staining. Bc1-2 immunoreactivity did not correlate with tumour histology, tumour stage, presence of lymph node metastases, or involvement of the lymphovascular space. The five year survival rate for patients with bc1-2 negative tumours was 34% and was 71% for patients with bc1-2 positive tumours. On multiple regression analysis (Cox proportional hazards model), bc1-2 expression and vascular permeation were independent predictors of overall survival.

CONCLUSIONS

Bcl-2 expression seems to be associated with less aggressive behaviour in early stage cervical carcinoma. The transition to bcl-2 independence may play an important role in tumour progression.

Dominant inhibitory Ras delays Sindbis virus-induced apoptosis in neuronal cells

Mature neurons are more resistant than dividing cells or differentiating neurons to Sindbis virus-induced apoptotic death. Therefore, we hypothesized that mitogenic signal transduction pathways may influence susceptibility to Sindbis virus-induced apoptosis. Since Ras, a 21-kDa GTP-binding protein, plays an important role in cellular proliferation and neuronal differentiation, we investigated the effect of an inducible dominant inhibitory Ras on Sindbis virus-induced death of a rat pheochromocytoma cell line, PC12 cells. Dexamethasone induction of dominant inhibitory Ras (Ha Ras(Asn17)) expression in transfected PC12 cell lines (MMTV-M17-21 and GSrasDN6 cells) resulted in a marked delay in Sindbis virus-induced apoptosis, compared with infected, uninduced cells. The delay in death after Sindbis virus infection in induced versus uninduced PC12 cells was not associated with differences in viral titers or viral infectivity. No delay in Sindbis virus-induced apoptosis was observed in Ha Ras(Asn17)-transfected PC12 cells if dexamethasone induction was initiated less than 12 h before Sindbis virus infection or in wild-type PC12 cells infected with a chimeric Sindbis virus construct that expresses Ha Ras(Asn17). The delay in Sindbis virus-induced apoptosis in induced Ha Ras(Asn17)-transfected PC12 cells was associated with a decrease in cellular DNA synthesis as measured by 5'-bromo-2'-deoxyuridine incorporation. Thus, in PC12 cells, inducible dominant inhibitory Ras inhibits cellular proliferation and delays Sindbis virus-induced apoptosis. These findings suggest that a Ras-dependent signaling pathway is a determinant of neuronal susceptibility to Sindbis virus-induced apoptosis.

Expression of programmed cell death regulatory p53 and bcl-2 proteins in oral lesions

With the ultimate goal of characterizing the molecular pathogenesis of oral cancer, the most predominant malignancy in India, immunocytochemical evaluation of p53 and bcl-2 proteins was carried out in hypeplastic oral mucosa, dysplastic oral mucosa and invasive oral cancer. All subjects gave a similar and almost uniform history of prolonged use of betal quid and tobacco. Expression of p53 was insignificant while bcl-2 was absent in hyperplastic leukoplakia lesions. Both proteins were however expressed in leukoplakia with apparent dysplasia. Almost all invasive cancer lesions showed high levels of both p53 and bcl-2. Good correlation was therefore evident between expression of these two proteins and increasing histologic abnormality. Moreover relative risk evaluation revealed that lesions expressing p53 and bcl-2 had a high probability of having a histology of dysplasia or worse. Since it has been previously shown that wild type p53 regulates the expression of bcl-2, it may be presumed that the protein detected in the dysplastic and malignant oral tissue is of the mutant type. It is also known that p53 is a positive regulator of programmed cell death or apoptosis while bcl-2 is an anti-apoptotic protein. This suggests the possibility that alterations in p53 followed by over-expression of bcl-2 occur early in oral carcinogenesis resulting in defective apoptosis and subsequent tumor progression.

Bc1-2 protects mice against fatal alphavirus encephalitis

Virus-induced apoptosis has been well characterized in vitro, but the role of apoptosis in viral pathogenesis is not well understood. The suicide of a cell in response to viral infection is postulated to be an important host defense for the organism, leading to a reduction in its total viral burden. However, virus-induced death of nonregenerating cells in the central nervous system may be detrimental to the host. Therefore, to investigate the role of apoptosis in the pathogenesis of fatal encephalitis, we constructed a recombinant alphavirus chimera that expresses the antiapoptotic gene, bcl-2, in virally infected neural cells. Infection of neonatal mice with the alphavirus chimera expressing human bcl-2 [Sindbis virus (SIN)/bcl-2] resulted in a significantly lower mortality rate (7.5%) as compared with infection with control chimeric viruses containing a chloramphenicol acetyltransferase (CAT) reporter gene (SIN/CAT) (78.1%) or bcl-2 containing a premature stop codon (SIN/bcl-2stop) (72.1%) (P < 0.001). Viral titers were reduced 5-fold 1 day after infection and 10-fold 6 days after infection in the brains of SIN/bcl-2-infected mice as compared to SIN/CAT or SIN/bcl-2stop-infected mice. In situ end labeling to detect apoptotic nuclei demonstrated a reduction in the number of foci of apoptotic cells in the brains of mice infected with SIN/bcl-2 as compared with SIN/bcl-2stop. The reduction in apoptosis was associated with a reduction in the number of foci of cells expressing alphavirus RNA. Thus, the antiapoptotic gene, bcl-2, suppresses viral replication and protects against a lethal viral disease, suggesting an interaction between cellular genetic control of viral replication and cell death.

Expression of Bax in relation to Bcl-2 and other predictive parameters in breast cancer

BACKGROUND

It has been suggested that modification of the physiological susceptibility to induction of programmed cell death in transformed cells contributes to the pathogenesis of cancer. One of the major regulators of cell death is the bcl-2 family. In breast cancer, altered expression of Bcl-2 has been described. Distribution of its counterpart Bax and the differential expression pattern have still to be evaluated.

PATIENTS AND METHODS

Bax expression was investigated by immunohistochemistry in 122 primary breast cancers. Results were correlated with expression of Bcl-2 and other variables of predictive value.

RESULTS

There was a positive association between Bax expression and histological grading, (over)expression of c-erbB-1 and -2 and proliferative activity. The correlation was most significant in cases where no concomitant Bcl-2 expression could be detected. In the same subgroup an inverse correlation with positivity for estrogen (and progesterone) receptors was observed. The presence of Bax was not significantly associated with either tumor type and size, nodal status or expression of c-erbB-3.

CONCLUSION

Expression of Bax was coupled with negative histopathological features, especially when expression of Bcl-2 was downregulated concomitantly. It may appear that alterations of the differential Bax/Bcl-2 expression pattern take part in deregulation of proliferation and loss of differentiation, thus playing an important role in malignant progression.