BIRinging chromosomes through cell division--and survivin' the experience

Intensity of survivin expression linked to features of aggressive relapsed/refractory diffuse large B-cell lymphoma

SPiReL is a phase II clinical trial evaluating combination immunotherapy, pembrolizumab and cyclophosphamide, with maveropepimut-S, in survivin-expressing relapsed/refractory (R/R) Diffuse Large B Cell Lymphoma (DLBCL). We describe baseline tumor survivin expression and associations with clinico-pathological variables in 25 participants. The median number of survivin-expressing cells was 99%, and the intensity of survivin expression within tumors was heterogeneous by semi-quantitative immunohistochemistry assessment. Tumors with higher numbers of cells expressing 2+/3+ survivin were associated with characteristics of poor outcome, (Lactate dehydrogenase and cell-of-origin). Greater total baseline tumor area was associated with lower proportions of 1+ cells and greater proportions of 2+/3+ cells. High intensity survivin expression is associated with aggressive clinical features supporting a pathobiological role in R/R DLBCL. Future prognostic models incorporating survivin as a clinical biomarker require assessment of intensity, overall expression and should include potential threshold effects of survivin in DLBCL pathobiology.

The prognostic role of survivin expression in breast cancer: A systematic review and meta-analysis

BACKGROUND

Breast cancer is a heterogeneous condition with variations in histopathological, genomic, and biological characteristics. Although clinicopathological prognostic factors and gene expression profiles are commonly used to guide treatment decisions in patients with breast cancer, there is still a need for new prognostic markers. One potential marker is survivin, a protein belonging to the apoptosis inhibitor family. However, studies examining the relationship between survivin and prognosis in breast cancer have yielded inconsistent results. This study aimed to evaluate the impact of survivin expression on the prognosis of breast cancer patients through a meta-analysis.

METHODS

Studies evaluating survivin expression were sourced from the PubMed, Embase, and Cochrane databases. We conducted a meta-analysis based on full-text articles that evaluated the relationship between survivin expression and survival by immunochemistry or polymerase chain reaction. The studies were initially divided into 2 groups based on the evaluation of overall survival (OS) and disease-free survival (DFS). Subsequently, each group was further categorized according to the method used to detect survivin expression. Statistical analyses for this study were conducted using Stata and JAMOVI.

RESULTS

After screening with keywords, we identified 24 retrospective studies evaluating OS and 15 retrospective studies evaluating DFS, which were included in the analysis. We found that the studies in the meta-analysis were not heterogeneous, and this remained consistent when categorizing the groups by survivin expression detection. Survivin expression was associated with OS (HR 1.23, 95% CI 0.81-1.65) and DFS (HR 0.89, CI 0.42-1.36), indicating poor prognosis. This significant relationship between survivin expression and survival persisted when the studies were categorized by the detection method, either immunohistochemistry or polymerase chain reaction.

CONCLUSION

In this study, we evaluated the prognostic significance of survivin expression in patients with breast cancer through a meta-analysis. These results support the use of survivin expression as a prognostic marker in breast cancer, potentially guiding treatment decisions.

Clinicopathological and functional implications of the inhibitor of apoptosis proteins survivin and XIAP in esophageal cancer

Based on their overexpression and important roles in progression and therapy-resistance in malignant diseases, the inhibitor of apoptosis protein family (IAP) members, survivin and X-linked inhibitor of apoptosis protein (XIAP), represent attractive candidates for targeted therapy. The present study investigated the prognostic and biological relevance of survivin and XIAP in esophageal squamous-cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC). Survivin and XIAP expression was analyzed by immunohistochemistry using tissue microarrays containing 120 ESCC and 90 EAC samples as well as the corresponding non-neoplastic esophageal mucosa samples. IAP expression levels were then correlated to clinicopathological parameters and overall survival to identify any associations. In addition, esophageal cancer cell lines were treated with the survivin inhibitor YM155, and the XIAP inhibitors Birinapant and GDC-0152 in vitro. Survivin and XIAP expression were significantly increased in EAC and ESCC when compared with tumor-adjacent mucosa. In patients with ESCC XIAP expression was associated with female gender and advanced tumor stages, and nuclear survivin expression was associated with poor grading. High XIAP expression was identified as an independent negative prognostic marker in ESCC. By contrast, XIAP inhibitors did not affect cancer cell viability in vitro, and the small molecule survivin inhibitor YM155 significantly reduced cell viability and proliferation in esophageal cancer cell lines. Western blot analysis revealed a dose dependent decrease of survivin accompanied by an increased poly (adenosine diphosphate-ribose) polymerase cleavage following YM155 treatment. These findings underline the potential role of survivin and XIAP in the oncogenesis of esophageal cancer and provide a rationale for future clinical studies investigating the therapeutic efficacy of IAP directed therapies in patients with esophageal cancer.

Targeting survivin for therapeutic discovery: past, present, and future promises

Survivin, the smallest member of the inhibitor of apoptosis protein (IAP) family, is overexpressed in cells of almost all cancers but not in most normal tissues in adults. Survivin expression is required for cancer cell survival and knocking down its expression or inhibiting its function using molecular approaches results in spontaneous apoptosis. Thus, survivin is an attractive and perhaps ideal target for cancer drug discovery. However, a US Food and Drug Administration (FDA)-approved drug targeting survivin has yet to emerge. In this Foundation Review, we examine and evaluate various strategies that have been used to target survivin and the stages of each survivin inhibitor to help understand this lack of success. We also provide future perspectives moving forward in targeting survivin for drug discovery.

A combination of YM-155, a small molecule survivin inhibitor, and IL-2 potently suppresses renal cell carcinoma in murine model

YM155, a small molecule inhibitor of the antiapoptotic protein survivin, has been developed as a potential anti-cancer drug. We investigated a combination therapy of YM155 and interleukin-2 (IL-2) in a mouse model of renal cell carcinoma (RCC). YM155 caused cell cycle arrest and apoptosis in renal cancer (RENCA) cells. Next, luciferase-expressing RENCA cells were implanted in the left kidney and the lung of BALB/c mice to develop RCC metastatic model. In this orthotopic renal and metastatic lung tumors models, YM155 and IL-2 additively decreased tumor weight, lung metastasis, and luciferin-stained tumor images. Also, the combination significantly suppressed regulatory T cells and myeloid-derived suppressor cells compared with single agent treatment. We suggest that a combination of YM155 and IL-2 can be tested as a potential therapeutic modality in patients with RCC.

Survivin is expressed in degenerated nucleus pulposus cells and is involved in proliferation and the prevention of apoptosis in vitro

Survivin is a unique inhibitor of apoptosis, which is frequently present within degenerated human nucleus pulposus (NP) cells. Survivin has been extensively investigated using proliferation and apoptosis assays in tumor cells; however, studies conducted on survivin in degenerative NP cells remain limited to date. The aim of the present study was to investigate survivin expression and its effects on the proliferation and apoptosis of degenerated NP cells in vitro. The expression levels of survivin in the NP cells of patients (>45 years) with lumbar disc degenerative disease and the NP cells of patients (<25 years) with lumbar vertebra fracture were assessed by reverse transcription‑quantitative polymerase chain reaction. The effects on in vitro proliferation and apoptosis were investigated through transfection with a specific small interfering (si)RNA. The results of the present study demonstrated that survivin was expressed in the degenerated NP cells, but was undetectable in normal NP cells at the mRNA level. Survivin suppression following transfection with a specific survivin‑siRNA reduced the proliferation rate of NP cells and enhanced sensitization to pro‑apoptotic stimuli. Therefore, survivin was shown to be expressed and exhibit an important role in the proliferation and prevention of apoptosis of degenerated NP cells. Studies on survivin in NP cells may aid in increasing the understanding of the complex processes underlying NP cell degeneration, and could provide fundamental information for gene therapy to inhibit this degeneration in vitro.

Survivin over-expression is correlated with a poor prognosis in esophageal cancer patients

BACKGROUND

The prognostic role of survivin in esophageal cancer (EC) remains controversial. This meta-analysis aimed to clarify the association of survivin with survival in EC patients.

METHODS

Relevant studies published up to November 2014 were identified using PubMed and Embase. Only studies in which survivin was detected through immunohistochemical staining were included. STATA 12.0 was used in this meta-analysis.

RESULTS

A total of 9 studies, which comprised 610 patients, were included in the meta-analysis. The combined hazard ratio (HR) of 1.76 (95% CI, 1.40-2.21; P<0.001) suggests that survivin overexpression in EC patients was significantly associated with poor overall survival. Moreover, the results showed a significant relationship between overall survival and survivin expression was also displayed in studies with a non-Asian country (HR, 1.75; 95% CI, 1.30-2.35), patient number ≥ 50 (HR, 1.86; 95% CI, 1.57-2.20), the cut-off level ≥ 5% (HR, 1.43; 95% CI, 0.94-2.17) and the esophageal squamous cell carcinoma (HR, 1.82; 95% CI, 1.43-2.30). However, combined odds ratio of survivin indicated that survivin overexpression has no correlation with stage, grade of differentiation, lymph node status, depth of invasion and distant metastasis of EC (P>0.05).

CONCLUSION

Survivin overexpression is associated with poor prognosis in EC patients.

CDK4 inhibition and doxorubicin mediate breast cancer cell apoptosis through Smad3 and survivin

Cyclin D1/CDK4 activity is upregulated in up to 50% of breast cancers and CDK4-mediated phosphorylation negatively regulates the TGFβ superfamily member Smad3. We sought to determine if CDK4 inhibition and doxorubicin chemotherapy could impact Smad3-mediated cell/colony growth and apoptosis in breast cancer cells. Parental and cyclin D1-overexpressing MCF7 cells were treated with CDK4 inhibitor, doxorubicin, or combination therapy and cell proliferation, apoptosis, colony formation, and expression of apoptotic proteins were evaluated using an MTS assay, TUNEL staining, 3D Matrigel assay, and apoptosis array/immunoblotting. Study cells were also transduced with WT Smad3 or a Smad3 construct resistant to CDK4 phosphorylation (5M) and colony formation and expression of apoptotic proteins were assessed. Treatment with CDK4 inhibitor/doxorubicin combination therapy, or transduction with 5M Smad3, resulted in a similar decrease in colony formation. Treating cyclin D overexpressing breast cancer cells with combination therapy also resulted in the greatest increase in apoptosis, resulted in decreased expression of anti-apoptotic proteins survivin and XIAP, and impacted subcellular localization of pro-apoptotic Smac/DIABLO. Additionally, transduction of 5M Smad3 and doxorubicin treatment resulted in the greatest change in apoptotic protein expression. Collectively, this work showed the impact of CDK4 inhibitor-mediated, Smad3-regulated tumor suppression, which was augmented in doxorubicin-treated cyclin D-overexpressing study cells.

Prognostic significance of survivin in breast cancer: meta-analysis

Survivin, an inhibitor of apoptosis protein, is a potentially prognostic factor and therapeutic target in breast carcinoma, but no consensus exists based on heterogeneous data. The aim of this present study is to clarify the prognostic relevance of survivin in breast cancer patients. Relevant articles were screened in PubMed and EMBASE databases. Patients' clinical characteristics, overall survival (OS), disease/recurrence-free survival (DFS/RFS) and positive expressed survivin rates were extracted for further analysis. Statistics extracted from Kaplan-Meier survival curves were calculated indirectly with methods developed by Parmar, Williamson, and Tierney. Multivariate Cox hazard regression analysis data were used directly in Stata 11.0. Pooled hazard ratio (HR) and 95% confidence interval (CI) were calculated to evaluate the prognostic role of survivin in breast cancer. Online literature search identified 23 articles containing 3,259 breast cancer patients. Our meta-analysis of all included studies about survival outcomes showed positive correlation between poor prognosis and survivin expression. Pooled HRs (95% CIs) for OS and DFS/RFS were 1.37 (1.12-1.68) and 1.34 (1.02-1.76), respectively. Subgroup analyses considering methods used to detect survivin (immunohistochemistry or not) and localization of survivin (whole, nuclear or cytoplasm of the cell) were also conducted, and all the above analyses supported the stability of the prognostic role of survivin. In addition, our study revealed a significant association between survivin expression and lymph node metastasis (OR: 2.74; 95% CI: 1.27-5.93) or stage of breast cancer (OR: 2.01; 95% CI: 1.29-3.13). Positive expression of survivin demonstrated a significantly higher risk of recurrence and decreased OS rates in breast cancer.

Human survivin and Trypanosoma cruzi calreticulin act in synergy against a murine melanoma in vivo

Immune-based anti-tumor or anti-angiogenic therapies hold considerable promise for the treatment of cancer. The first approach seeks to activate tumor antigen-specific T lymphocytes while, the second, delays tumor growth by interfering with blood supply. Tumor Associated Antigens are often employed to target tumors with therapeutic drugs, but some are also essential for tumor viability. Survivin (Surv) is a member of the inhibitor of apoptosis protein family that is considered a Tumor Associated Antigen important for cancer cell viability and proliferation. On the other hand, Trypanosoma cruzi (the agent of Chagas’ disease) calreticulin (TcCRT) displays remarkable anti-angiogenic properties. Because these molecules are associated with different tumor targets, we reasoned that immunization with a Surv-encoding plasmid (pSurv) and concomitant TcCRT administration should generate a stronger anti-tumor response than application of either treatment separately. To evaluate this possibility, C57BL/6 mice were immunized with pSurv and challenged with an isogenic melanoma cell line that had been pre-incubated with recombinant TcCRT (rTcCRT). Following tumor cell inoculation, mice were injected with additional doses of rTcCRT. For the combined regimen we observed in mice that: i). Tumor growth was impaired, ii). Humoral anti-rTcCRT immunity was induced and, iii).In vitro rTcCRT bound to melanocytes, thereby promoting the incorporation of human C1q and subsequent macrophage phagocytosis of tumor cells. These observations are interpreted to reflect the consequence of the following sequence of events: rTcCRT anti-angiogenic activity leads to stress in tumor cells. Murine CRT is then translocated to the external membrane where, together with rTcCRT, complement C1 is captured, thus promoting tumor phagocytosis. Presentation of the Tumor Associated Antigen Surv induces the adaptive anti-tumor immunity and, independently, mediates anti-endothelial cell immunity leading to an important delay in tumor growth.

The prognostic value of survivin expression in patients with colorectal carcinoma: a meta-analysis

OBJECTIVE

The prognostic role of survivin in colorectal carcinoma remains controversial. This meta-analysis aimed to explore the association between survivin expression and survival outcomes in patients with colorectal carcinoma.

METHODS

A comprehensive literature search for relevant studies published up to April 2013 was performed using PubMed, MEDLINE and ISI Web of Science. Only articles in which survivin was detected by immunohistochemical staining were included. This meta-analysis was done using STATA and Review Manager.

RESULTS

A total of 1784 patients from 14 studies were included in the analysis. Our results showed that survivin overexpression in patients with colorectal carcinoma was significantly associated with poor overall survival (hazard ratio, 1.505; 95% confidence interval, 1.197-1.893; P = 0.000) and disease-free survival (hazard ratio, 2.323; 95% confidence interval, 1.687-3.199; P = 0.000). The results indicated that a significant relationship between survivin expression and overall survival was also exhibited in studies with an Asian country (hazard ratio, 1.684; 95% confidence interval, 1.477-1.921), patient number >100 (hazard ratio, 1.604; 95% confidence interval, 1.371-1.877), the cut-off level <50% (hazard ratio, 1.449; 95% confidence interval, 1.045-2.010), the percentage of survivin overexpression >50% (hazard ratio, 1.528; 95% confidence interval, 1.056-2.211) and the hazard ratio estimated (hazard ratio, 1.643; 95% confidence interval, 1.262-2.139). Moreover, upregulation of survivin was associated with stages (III/IV vs. I/II: odds ratio, 1.08; 95% confidence interval, 0.80-1.46), the depth of invasion (T3/T4 vs. T1/T2: odds ratio, 1.79; 95% confidence interval 0.67-4.74), lymph node metastasis (positive vs. negative: odds ratio, 1.49; 95% confidence interval, 0.99-2.26), distant metastasis (positive vs. negative: odds ratio, 2.37; 95% confidence interval, 0.99-5.72) and grade of differentiation (well/moderate vs. poor: odds ratio, 1.02; 95% confidence interval, 0.43-2.41), but without significance.

CONCLUSION

The present meta-analysis indicated that upregulation of survivin was associated with poor prognosis in patients with colorectal carcinoma.

Polypeptide chain release factor eRF3 is a novel molecular partner of survivin

The eukaryotic class II polypeptide chain release factor (eRF3) is an eRF1- and ribosome-dependent GTPase involved in translation termination of protein biosynthesis. eRF3 is a multifunctional protein that is also involved in chromosomal segregation and cytokinesis during mitosis. Survivin is a member of the inhibitor of apoptosis protein (IAP) family that is involved in the organisation of spindle and cell apoptosis. Interaction between survivin and eRF3a-F3 or eRF3b, encoded by the GSPT1 and GSPT2 genes, respectively, was confirmed using yeast two-hybrid (Y2H) and pull-down assays in vitro, and co-immunoprecipitation in vivo. The domains involved in the formation of the survivin-eRF3s complex have been identified. The sites on survivin that interact with eRF3 are located in the baculovirus IAP repeat domain (residues 65-76), which forms a beta-strand structure with an overall negative charge. The sites on eRF3 that interact with survivin were localised to the N-terminal domain(NTD; residues 131-200). Cell localisation experiments indicate that both factors are in the nucleus, suggesting that they cooperatively function in nuclear processes.

Noscapine induced apoptosis via downregulation of survivin in human neuroblastoma cells having wild type or null p53

Neuroblastoma is the most common extracranial solid tumor of childhood. It accounts for 15% of pediatric cancer deaths. Chemotherapy is the mainstay of treatment in children with advanced neuroblastoma. Noscapine, a nontoxic natural compound, can trigger apoptosis in many cancer types. We now show that p53 is dispensable for Noscapine-induced cell death in neuroblastoma cell lines, proapoptotic response to this promising chemopreventive agent is mediated by suppression of survivin protein expression. The Noscapine treatment increased levels of total and Ser(15)-phosphorylated p53 protein in SK-SY5Y cells, but the proapoptotic response to this agent was maintained even after knockdown of the p53 protein level. Exposure of SK-SY5Y and LA1-5S cells to Noscapine resulted in a marked decrease in protein and mRNA level of survivin as early as 12 hours after treatment. Ectopic expression of survivin conferred statistically significant protection against Noscapine-mediated cytoplasmic histone-associated apoptotic DNA fragmentation. Also, the Noscapine-induced apoptosis was modestly but statistically significantly augmented by RNA interference of survivin in both cell lines. Furthermore, Noscapine-induced apoptotic cell death was associated with activation of caspase-3 and cleavage of PARP. In conclusion, the present study provides novel insight into the molecular circuitry of Noscapine-induced apoptosis to indicate suppression of survivin expression as a critical mediator of this process.

Sp1 upregulates survivin expression in adenocarcinoma of lung cell line A549

Survivin has been implicated in tumor genesis, progression, and resistance to anticancer agents. However, the precise regulatory mechanism for survivin expression is not thoroughly defined. In this study, we showed that Sp1 was co-overexpressed with survivin in adenocarcinoma of lung cells A549, but not in differentiated human bronchial epithelial cells 4F0439 or small airway epithelial cells 3F1584. Subsequently, transfection experiments demonstrated that the inhibition of Sp1 signaling suppressed survivin expression in A549 cells, whereas Sp1 overexpression increased the level of survivin protein as well as its mRNA. We also found that Sp1 could decrease capase-9 activity, which is shown to be suppressed by survivin during apoptosis inhibition. Finally, Luciferase activity and ChIP assays revealed that Sp1 activated survivin promoter by direct interaction with it. Taken together, our data suggest Sp1 plays a potent role in the upregulation of survivin expression in lung cancer cells at the transcriptional level.

The Fas-mediated apoptotic pathway in cardiac myxoma

Cardiac myxoma is the most common primary tumor of the heart. The existence of apoptosis in cardiac myxoma has been demonstrated. The purpose of this investigation was to elucidate the pathway of apoptosis and the cell cycle in cardiac myxomas. This study had 2 parts: investigation of a cultured cardiac myxoma cell line and the analysis of data from 20 patients with cardiac myxoma that was surgically excised. Apoptosis signal transduction was determined by assessing DNA fragmentation, Fas ligand (FasL), Fas, tumor necrosis factor-α (TNF-α), caspase-3, and terminal deoxynucleotidyl transferase nick-end labeling (TUNEL) assay through immunohistochemical stain, quantitative reverse transcriptase- polymerase chain reaction (RT-PCR), and Western blot analysis. The patient population consisted of 12 (60%) women and 8 (40%) men with a mean age of 46 years (range = 32-64 years). All cases of myxoma were sporadic myxomas rather than familial. Clinical presentations included asymptomatic (26%), dyspnea (44%), stroke (9%), chest pain (9%), and fever (11%). All myxomas were located in the left atrium. Pathological scores for inflammation, cellularity, calcification, and thrombosis were not related to myxoma location or clinical events. In cardiac myxoma, apoptosis documented by TUNEL (70.9% ± 17.6%) and the caspase-3 (66.5% ± 32.5%) final common pathway is characterized by the extrinsic Fas/ FasL dependent pathway (positive stained 70.9% ± 19.2%; 26.0% ± 17.2%, respectively), but not the intrinsic pathway. The RT-PCR and Western Blot analysis (Fas/FasL, TNF-α, caspase-3, and apoptosis) of the cardiac myxoma and cultured cardiac myxoma cells confirmed the immunochemical results. The extrinsic Fas/FasL-dependent apoptosis pathways in cardiac myxomas were proved by both RNA and protein levels.

Endothelial cells from humans and mice with polycystic kidney disease are characterized by polyploidy and chromosome segregation defects through survivin down-regulation

Autosomal-dominant polycystic kidney disease (ADPKD) is the most common hereditary and systemic disorder associated with various cardiovascular complications. It has been implicated with dysfunction in primary cilia. We and others have shown that the immediate function of endothelial cilia is to sense extracellular signal. The long-term function of cilia is hypothesized to regulate cell cycle. Here, we show that ciliary function (polycystins) and structure (polaris) are required for proper cellular division. Cilia mutant cells undergo abnormal cell division with apparent defects in mitotic spindle formation, cellular spindle assembly checkpoint and centrosome amplification. Down-regulation of the chromosomal passenger survivin contributes to these abnormalities, which further result in cell polyploidy. Re-expression of survivin restores a competent spindle assembly checkpoint and reduces polyploidy. Aged animals show a more severe phenotype in cellular division, consistent with progression of cardiovascular complications seen in older ADPKD patients. For the first time, we show that structure and function of mechanosensory cilia are crucial in maintaining proper cellular proliferation. Furthermore, developmental aging plays a crucial role in the progression of these abnormal cellular phenotypes. We propose that abnormal function or structure of primary cilia not only causes failure to transmit extracellular signals, but also is associated with cytokinesis defects in both mice and humans with polycystic kidney disease.

Expression and prognostic significance of survivin in the progression of bladder transitional cell cancer

The expression of survivin, a member of inhibitor of apoptosis (IAP) family, was examined in bladder transitional cell cancer (BTCC) tissue and adjacent normal tissues to examine its clinical implication in the development of BTCC. Thirty specimens of bladder cancer were detected for the expression of survivin by using immunohistochemistry and real-time quantitative reverse transcription polymerase chain reaction (RT-QPCR) in BTCC tissue and adjacent normal tissues. Our results showed that the positive rate of survivin immunostaining specimen were 0 and 60% (18/30) in the adjacent normal tissues, bladder cancer, respectively. The-DeltaDeltaCT value of survivin in bladder cancer tissue was 10.2829 (9.0034-11.5624) times that in the adjacent normal tissues. The expressions of survivin were correlated with the pathological grades of tumor and clinical stages. It is concluded that there was only weak expression of survivin mRNA in the adjacent normal tissues, but the expression of survivin mRNA in bladder cancer tissue was much higher than that in the adjacent normal tissues and the expression of survivin was correlated with pathological grades and clinical stages of tumor.

Survivin expression in the progression of chronic myeloid leukemia: A sequential study in 16 patients

An increase in the proliferation and resistance to apoptosis of leukemic cells has been found in chronic myeloid leukemia (CML) as the disease evolves from the chronic phase to blast crisis (BC). To contribute to a better knowledge of the molecular mechanisms involved in such biological abnormality, the expression of the survivin gene was studied by quantitative real-time polymerase chain reaction (PCR) in the chronic phase of CML and at BC in 16 patients in whom sequential RNA samples from the 2 phases of the disease were available. Survivin was significantly overexpressed in both the chronic phase and BC as compared with granulocytes from controls. In BC, survivin expression was 7-fold higher than in the chronic phase, with such an increase being more pronounced in the myeloid (17-fold) than in the lymphoid cases (3-fold) (P = 0.03). Cell proliferation was significantly increased at BC, with Ki-67 expression being 2.8-fold higher than in the chronic phase. Despite the overexpression of both survivin and Ki-67 at BC, no significant correlation between their expression levels was observed. These data support a possible role for survivin overexpression in the pathogenesis of the progression of CML. However, further studies are required to elucidate the possible prognostic importance of such biological findings in this disease.

Role of IFN-γ-STAT1 pathway in human gastric adenocarcinoma

AIM: To investigate relationships among STAT1, Caspase-7 and p21^waf in gastric adenocarcinoma tissue and gastric adenocarcinoma cell SGC7901, and to shed light on features of IFN-γ-STAT1 pathway in gastric adenocarcinoma.

METHODS: Gastric adenocarcinoma tissue was tested by immunohistochemical method. SGC7901 cell was treated with IFN-γ and STAT1 antisense oligonucleotides, and mRNA and protein expression was detected using RT-PCR, immunocytochemistry and image analysis methods. Apoptosis was determined by Hoechest 33258.

RESULTS: Caspase-7 was positive correlation with STAT1 and p21^waf (r = 0.32, 0.22, both P < 0.05) in gastric adenocarcinoma tissue. IFN-γ promoted mRNA and protein expression of STAT1, Caspase-7 and p21^waf was up-regulated in SGC7901 cell (P < 0.05). After treatment with IFN-γ along with varied concentrations of STAT1 antisense oligonucleotides, significantly lower STAT1 mRNA and protein expression was observed than IFN-γ used alone in SGC7901 cells, which showed a concentration-dependent manner (P < 0.05); significantly lower Caspase-7 and P21^waf protein expression was observed than IFN-γ used alone in SGC7901 cell in a concentration-dependent manner (P < 0.05). However, mRNA expression of Caspase-7 was down-regulated first and then up-regulated, while mRNA expression of p21waf was up-regulated first and then down-regulated.

CONCLUSION: There is a IFN-γ-STAT1 pathway in gastric adenocarcinoma tissue and SGC7901 cell line. IFN-γ-STAT1 could up-regulate the expression of Caspase-7 and p21^waf in gastric adenocarcinoma, but could not induce apoptosis. The downstream molecular of IFN-γ- STAT1 pathway has different expression features in mRNA and protein expression level in gastric adenocarcinoma.

Development of cell-cycle inhibitors for cancer therapy

The cell cycle governs the transition from quiescence through cell growth to proliferation. The key parts of the cell cycle machinery are the cyclin-dependent kinases (CDKS) and the regulatory proteins called cyclins. The CDKS are rational targets for cancer therapy because their expression in cancer cells is often aberrant and their inhibition can induce cell death. Inhibitors of CDKS can also block transcription.Several drugs targeting the cell cycle have entered clinical trials. These agents include flavopiridol, indisulam, AZD5438, SNS-032, bryostatin-1, seliciclib, PD 0332991, and SCH 727965. Phase i studies have demonstrated that these drugs can generally be administered safely. Phase ii studies have shown little single-agent activity in solid tumors, but combination studies with cytotoxic chemotherapy have been more promising. In hematologic malignancies, reports have shown encouraging single-agent and combination activity. Pharmacodynamic studies show that the dose and schedule of these drugs are crucial to permit maximum therapeutic effect.

Expression of cortactin and survivin in renal cell carcinoma associated with tumor aggressiveness

PURPOSE

We tested the hypothesis that the expression of cortactin and survivin in renal cell carcinomas (RCCs) correlates with more advanced stages of the disease.

METHODS

Immunohistochemical analysis of cortactin and survivin expression (scored on a scale of 0-400) was performed in 124 renal cell carcinomas including clear cell renal cell carcinoma (CRCC), papillary RCC (PRCC), CRCC with sarcomatoid differentiation (SRCC), chromophobe RCC (ChRCC), and CRCC with granular cell differentiation (GRCC).

RESULTS

Higher cortactin scores in CRCC were significantly correlated with higher T (p = 0.021) and N stages (p = 0.036), and nuclear grade (p = 0.012). Higher cortactin immunostaining scores were associated with higher mortality (p = 0.035). In addition, the survivin scores were significantly higher in the more aggressive GRCC and SRCC than in CRCC, suggesting a significant role of survivin expression in transformation of tumor cells to a more malignant phenotype.

CONCLUSIONS

Higher expression of cortactin and survivin significantly correlated with advanced clinicopathological stage. Our findings support the potential targeting of survivin and cortactin for the development of novel therapeutic strategies for renal cell carcinoma.

Survivin and caspase-3 expression in breast cancer: correlation with prognostic parameters, proliferation, angiogenesis, and outcome

BACKGROUND

Survivin is an inhibitor of apoptosis protein that is overexpressed in most human cancers, including breast, but is not expressed in normal tissue. Survivin is associated with more aggressive behavior and decreased survival in a variety of tumor types. It regulates the G2/M phase of the cell cycle by associating with mitotic spindle microtubules, and it directly inhibits caspase-3 and caspase-7 activity. We used a breast cancer tissue microarray to assess survivin and caspase-3 expression in breast cancer and to correlate both markers with proliferation (MIB-1), angiogenesis (CD31), and prognosis.

DESIGN

A breast cancer tissue microarray with a total of 190 1-mm tissue samples (2 from each specimen) were immunostained for survivin, caspase-3, MIB-1, and CD31. The microarray contains 91 cases of breast carcinoma diagnosed at Emory University Hospital between 1992 and 2000, and 4 normal breast tissue controls. Follow-up information was obtained from hospital records and the Winship Cancer Center database.

RESULTS

Eighty-four percent of breast carcinoma showed nuclear survivin expression. Normal breast tissue was immunonegative. Fifty-seven percent and 43% of breast cancer showed reduced and absent caspase-3 expression, respectively. Survivin (nuclear) and caspase (nuclear/cytoplasmic) expression showed significant correlation with histologic grade (P=0.008 and 0.041) and MIB-1 expression (P=0.033 and 0.012). Survivin nuclear expression also correlated significantly with tumor stage (P=0.012) and tended to correlate with estrogen receptor (P=0.050). There was no significant correlation between survivin and caspase expression. Furthermore, there was no correlation of both markers with other clinicopathologic parameters (age, tumor size, histologic type, progesterone receptor, Her-2 neu status, lymph node status), angiogenesis (CD31), or outcome (overall and disease-free survival).

CONCLUSIONS

Survivin and caspase-3 expression correlate with poor prognostic parameters (higher histologic grade and high proliferation), but not with outcome, in breast carcinoma patients.

Expression of survivin and enhanced polypogenesis in nasal polyps

BACKGROUND

The pathogenesis of nasal polyps still is not clear. This disease is believed to be inflammation related. Previous research has indicated that apoptosis in inflammatory cells is an important factor in the resolution of inflammation. Survivin is regarded as a novel member of the group of inhibitors of apoptosis proteins. It is overexpressed in a number of tumor types. The objective of this study was to investigate the expression of the survivin gene in human nasal polyps.

METHODS

We investigated the expression of survivin in nasal polyps of adult patients with chronic rhinosinusitis. Specimens of nasal polyps were harvested during endonasal sinus surgery (n=22), and the normal mucosa surrounding the nasal polyp tissues or inferior turbinate tissues served as control (n=7). Immunohistochemical staining, reverse transcription polymerase chain reaction (RT-PCR), and Western blotting were performed for detecting the expression of survivin in the nasal polyps.

RESULTS

This study has clearly shown that immunoreactivity of survivin significantly increased in the nasal polyp compared with nasal mucosa specimens surrounding nasal polyps (p<0.001). The higher expression of survivin Western blotting and RT-PCR also was observed in the nasal polyp but not in normal nasal mucosa.

CONCLUSION

With a markedly increased expression of survivin in nasal polyps at both the mRNA and the protein levels, we believe the elevated expression of survivin might play an important role of development in nasal polyps.

Oncolytic adenovirus-mediated shRNA against Apollon inhibits tumor cell growth and enhances antitumor effect of 5-fluorouracil

Apollon, a membrane-associated inhibitor of apoptosis protein, protects cells against apoptosis and is upregulated in certain tumor cells. In this study, the effects of Apollon protein knockdown by RNA interference on the growth of human HeLa, HT-1080 and MCF-7 cells in vitro and in vivo were investigated. An oncolytic adenovirus (ZD55) containing the RNA polymerase III-dependent U6 promoter to express short hairpin RNA (shRNA) directed against Apollon (ZD55-siApollon) was constructed. Our data show that ZD55-siApollon successfully exerts a gene knockdown effect and causes the inhibition of tumor cell growth both in culture and in athymic mice in vivo. Cell cycle analysis, 4',6-diamidino-2-phenylindole staining and western blot analysis reveal that ZD55-siApollon-mediated suppression of Apollon induces apoptosis. Intratumoral injection of ZD55-siApollon significantly inhibits tumor growth in HT-1080 xenograft mice. Furthermore, ZD55-siApollon enhances the antitumor effect of 5-fluorouracil, a chemotherapeutic agent. In conclusion, these results suggest that the depletion of Apollon by oncolytic adenovirus-shRNA delivery system provides a promising method for cancer therapy.

The tumor gene survivin is highly expressed in adult renal tubular cells: implications for a pathophysiological role in the kidney

The inhibitor of apoptosis protein survivin is of critical importance for regulation of cellular division and survival. Published data point to a restricted function of survivin in embryonic development and cancer; thus survivin has been broadly proposed as an ideal molecular target for specific anti-cancer therapy. In contrast to this paradigm, we report here broad expression of survivin in adult differentiated tissues, as demonstrated at the mRNA and protein levels. Focusing on the kidney, survivin is strongly expressed in proximal tubuli, particularly at the apical membrane, which can be verified in rat, mouse, and human kidneys. In the latter, survivin expression seems to be even stronger in proximal tubuli than in adjacent cancerous tissue. Primary and immortalized human renal tubular cells also showed high levels of survivin protein expression, and RNA interference resulted in a partial G(2)/M arrest of the cell cycle and increased rate of apoptosis. In conclusion, survivin may be of importance for renal pathophysiology and pathology. The predominant apical expression of survivin may indicate a further, yet unknown, function. Interventional strategies to inhibit survivin's function in malignancy need to be carefully (re)evaluated for renal side effects, as well as for other possible organ dysfunctions.

Stress-dependent regulation of Pbh1, a BIR domain-containing protein, in the fission yeast

To elicit the physiological roles of Pbh1, a baculoviral IAP repeat (BIR) domain-containing protein, in Schizosaccharomyces pombe, we investigated if Pbh1 expression is regulated by stress. The upstream region (1221 bp) of the pbh1 gene was fused into the promoterless beta-galactosidase gene of the shuttle vector YEp367R, and the resultant fusion plasmid was named pPbh04. The synthesis of beta-galactosidase from the pbh1-lacZ fusion gene was markedly enhanced by sodium nitroprusside (SNP) generating nitric oxide. The basal expression of the pbh1 gene required the presence of Pap1. Pap1 also mediated the induction of the pbh1 gene by SNP and nitrogen starvation. Pap1-dependent induction of the pbh1 gene by SNP was confirmed by the enhanced level of the pbh1 mRNA in Pap1-positive cells but not in Pap1-negative cells. Taken together, it was demonstrated that the pbh1 genes are positively regulated by nitrosative and nitrogen starvation stresses in Pap1-dependent manner.

Survivin expression in tuberous sclerosis complex cells

Tuberous Sclerosis Complex (TSC) is a tumor suppressor gene disorder with mutations of TSC1/TSC2 genes. This leads to the development of hamartomas that most frequently affect central nervous system, kidney, and skin. Angiomyolipomas are abdominal masses made up of muscle vessels and adipose tissues that grow mostly in proximity to kidneys and liver. Bleeding and kidney failure are the major justification for surgery. This study shows that angiomyolipoma-derived human smooth muscle TSC2-/- cells express the apoptosis inhibitor protein survivin when exposed to IGF-1. Survivin expression is also triggered whenever culture conditions perturb normal TSC2-/- cell function, such as the omission of EGF from the growth medium, the supplementation of anti-EGFR, blockade of PI3K and ERK, or inhibition of mTOR. Interestingly, single or simultaneous inhibition of PI3K by LY294002 and ERK by PD98059 does not prevent IGF-1-mediated survivin expression. Apoptogenic Smac/DIABLO, which is constitutively expressed by TSC2-/- A+ cells, is down-regulated by IGF-1 even in the presence of LY294002 and PD98059. These cells release IGF-1 by means of a negative feedback-regulated mechanism that is overrun when they are exposed to antibodies to IGF-1R, which increases the released amount by more than 400%. The autocrine release of IGF-1 may therefore be a powerful mechanism of survival of the tightly packed cells in the thick-walled vessels of TSC angiomyolipoma and in lymphangioleiomyomatosis (LAM) nodules. Future experimental therapies for TSC and LAM may result from the targeted inhibition of survivin, which may enhance sensitivity to TSC2 therapy.

Survivin expression in tuberous sclerosis complex cells

Tuberous Sclerosis Complex (TSC) is a tumor suppressor gene disorder with mutations of TSC1/TSC2 genes. This leads to the development of hamartomas that most frequently affect central nervous system, kidney, and skin. Angiomyolipomas are abdominal masses made up of muscle vessels and adipose tissues that grow mostly in proximity to kidneys and liver. Bleeding and kidney failure are the major justification for surgery. This study shows that angiomyolipoma-derived human smooth muscle TSC2-/- cells express the apoptosis inhibitor protein survivin when exposed to IGF-1. Survivin expression is also triggered whenever culture conditions perturb normal TSC2-/- cell function, such as the omission of EGF from the growth medium, the supplementation of anti-EGFR, blockade of PI3K and ERK, or inhibition of mTOR. Interestingly, single or simultaneous inhibition of PI3K by LY294002 and ERK by PD98059 does not prevent IGF-1-mediated survivin expression. Apoptogenic Smac/DIABLO, which is constitutively expressed by TSC2-/- A+ cells, is down-regulated by IGF-1 even in the presence of LY294002 and PD98059. These cells release IGF-1 by means of a negative feedback-regulated mechanism that is overrun when they are exposed to antibodies to IGF-1R, which increases the released amount by more than 400%. The autocrine release of IGF-1 may therefore be a powerful mechanism of survival of the tightly packed cells in the thick-walled vessels of TSC angiomyolipoma and in lymphangioleiomyomatosis (LAM) nodules. Future experimental therapies for TSC and LAM may result from the targeted inhibition of survivin, which may enhance sensitivity to TSC2 therapy.

Survivin: Potential role in diagnosis, prognosis and targeted therapy of gastric cancer

Survivin is a protein that is highly expressed in a vast number of malignancies, but is minimally expressed in normal tissues. It plays a role as an inhibitor of cell death in cancer cells, thus facilitating the growth of these cells. In the case of gastric cancer, survivin is over-expressed in tumor cells and plays a role in the carcinogenesis process. Several studies on gastric cancer have indicated that there is a relationship between survivin expression and the ultimate behavior of the carcinoma. Since the expression pattern of survivin is selective to cancer cells, it has been described as an “ideal target” for cancer therapy. Currently, several pre-clinical and clinical trials are on-going to investigate the effects of interfering with survivin function in cancer cells as a biologic therapy. Survivin is a potentially significant protein in the diagnosis, prognosis and treatment of gastric tumors.

The clinical significance of autoantibodies in gastrointestinal malignancies: an overview

Autoimmunity can be associated with cancer and one of the forms of its expression is the development of antibodies to autologous cellular antigens. The types of cellular proteins which induce autoantibody responses in gastrointestinal malignancies are quite varied and include cellular proteins encoded by mutated normal genes (p53), cellular proteins that are overexpressed and/or aberrantly expressed in malignant tissues (carcinoembryonic antigen), inhibitors of apoptosis (survivin and livin), major components of mucus (mucins), surface receptors of apoptosis (Fas) and nuclear-restricted proteins (double-stranded DNA, single-stranded DNA and Sm family proteins). In the past few years, due to the great clinical interest and the advancement in detection techniques, the above list has grown significantly and a large number of cancer-related antigens, which trigger a specific humoral immune response to the host, have also been identified. The authors review the autoantibodies associated with gastrointestinal malignancies and their clinical implications.

Suppression of tumor growth using antisense oligonucleotide against survivin in an orthotopic transplant model of human hepatocellular carcinoma in nude mice

Survivin, an inhibitor of apoptosis protein, deserves attention as a selective target for cancer therapy because it is overexpressed in many cancers, including human hepatocellular carcinoma (HCC). Here, we report a novel antisense oligonucleotide (ASO) against survivin for its effectiveness against tumor growth both in vitro and in vivo, and providing evidence in treatment for HCC. Initially, transfection of liver tumor cells HepG2 with ASO resulted in significant cells growth inhibition and reduction expression of survivin mRNA and protein, in a dose-dependent manner. Using caspase-3 protease activation assays, we observed that ASO has induced significantly greater apoptosis rate compared to control oligonucleotides. Furthermore, we used an orthotopic transplant model of HCC in nude mice to investigate the effect of ASO on tumor growth in vivo, and ASO reagents were delivered by intravenous injection. Interestingly, this systemic treatment also resulted in significant inhibition in tumor growth. Tumor growth in mice treated with ASO (50 and 75 mg/kg per day) was significantly inhibited (45.31% and 60.94%, respectively) compared with saline-injected group (p < 0.01), in a dose-dependent manner, and the effect of ASO on tumor growth was associated with downregulation of survivin in tumor xenografts. Moreover, the level of serum alpha-fetoprotein in ASO-treated groups was also decreased in a dose-dependent manner. Taken together, these data suggest that the usefulness of survivin ASO could potentially be a promising gene therapy approach to treatment of HCC.

HBXIP, cellular target of hepatitis B virus oncoprotein, is a regulator of centrosome dynamics and cytokinesis

Hepatitis B virus accounts for more than 1 million cancer deaths annually, but the mechanism by which this virus promotes hepatocellular carcinoma remains unclear. The hepatitis B virus genome encodes an oncoprotein, HBx, which binds various cellular proteins including HBXIP. We show here that HBXIP is a regulator of centrosome duplication, required for bipolar spindle formation in HeLa human carcinoma cells and primary mouse embryonic fibroblast cells. We found that most cells deficient in HBXIP arrest in prometaphase with monopolar spindles whereas HBXIP overexpression causes tripolar or multipolar spindles due to excessive centrosome replication. Additionally, a defect in cytokinesis was seen in HBXIP-deficient HeLa cells, with most cells failing to complete division and succumbing eventually to apoptosis. Expression of viral HBx in HeLa cells mimicked the effects of HBXIP overexpression, causing excessive centrosome replication, resulting in tripolar and multipolar spindles and defective cytokinesis. Immunolocalization and fluorescent protein tagging experiments showed that HBXIP associates with microtubules of dividing cells and colocalizes with HBx on centrosomes. Thus, viral HBx and its cellular target HBXIP regulate centrosome dynamics and cytokinesis affecting genetic stability. In vivo experiments using antisense oligonucleotides targeting HBXIP in a mouse model of liver regeneration showed a requirement for HBXIP for growth and survival of replicating hepatocytes. Thus, HBXIP is a critical regulator of hepatocyte cell growth in vivo, making it a strong candidate for explaining the tumorigenic actions of viral HBx.

Survivin and glycodelin transcriptional activity in node-positive early breast cancer: mRNA expression of two key regulators of cell survival

INTRODUCTION

Glycodelin and survivin are key polypeptide regulators of cellular proliferation, apoptosis and angiogenesis. In view of contradictory reports on their functional role in tumors, we studied their transcriptional levels in localized breast cancer.

PATIENTS AND METHODS

Glycodelin and survivin messenger ribonucleic acid (mRNA) was isolated and amplified by quantitative reverse-trancription PCR from paraffin-embedded breast carcinomas of 275 women. A normalized score was calculated by the use of GAPDH, RPL37A reference genes and was correlated with clinicopathologic/molecular parameters and patient outcome.

RESULTS

A total of 272 patients were eligible, most harbored stage III node-positive breast carcinomas larger than 2 cm. Glycodelin mRNA was expressed in 68 patients (25%), more frequently in premenopausal women (P = 0.01) and those with HER2 mRNA-positive tumors (P = 0.02). Survivin mRNA was present in 263 tumors (97%) and its levels correlated significantly with high nuclear grade, VEGF mRNA and p53 mRNA presence (P < 0.05). At a median follow-up of 64 months, neither glycodelin nor survivin mRNA expression demonstrated prognostic utility for overall or disease-free survival at univariate and multivariate analysis.

CONCLUSIONS

Glycodelin and survivin transcriptional activity are associated with adverse clinicopathologic and molecular characteristics of node-positive primary breast cancer but do not predict patient outcome. Further study is needed for illumination of their functional roles in tumorigenesis.

Survivin mutant (Surv-DD70, 71AA) disrupts the interaction of Survivin with Aurora B and causes multinucleation in HeLa cells

Survivin is associated with Aurora B, inner centromere protein (INCENP), and borealin to form a chromosomal passenger complex that plays multiple roles during cell division. We used mutational analysis to study interaction of Survivin with Aurora B and the effect of this interaction on cell division. A Survivin mutant with the terminal domain deleted (Survivin 1-107) bound Aurora B as efficiently as Survivin wild type. This indicated that the proximal BIR domain of Survivin was responsible for Survivin binding to Aurora B. Survivin mutants (Surv-R18A, Surv-D53A, and Sur-KK78, and 79AA) all bound to Aurora B efficiently, but mutation in the conserved amino acid residues of the acidic patch on Survivin (Surv-DD70, 71AA) abolished the direct interaction of Survivin and Aurora B. The Survivin mutant (Surv-DD70, 71AA) localized diffusely in metaphase and failed to successfully accumulate in the midbody during cytokinesis. Furthermore, over-expression of the Survivin mutant (Surv-DD70, 71AA) severely disturbed cytokinesis, resulting in multinucleation in HeLa cell. This indicated that the direct interaction of Survivin and Aurora B was critical for the correct location of Survivin and the function of the Survivin complex in cell division.

Apoptosis-based therapies and drug targets

The pathogenesis of many diseases is most closely connected with aberrantly regulated apoptotic cell death. The past 15 years have witnessed an explosion in the basic knowledge of mechanisms that regulate apoptosis and the mediators that either trigger or inhibit cell death. Consequently, great interest has emerged in devising therapeutic strategies for modulating the key molecules of life-and-death decisions. Numerous novel approaches are currently being followed employing gene therapy and antisense strategies, recombinant biologics or classical organic and combinatorial chemistry in order to target specific apoptotic regulators. Although drug development is still in its infancy, several therapeutics have progressed to clinical testing or have even been approved in record time. This review outlines the recent advances in the field of apoptosis-based therapies and explores some highlights of a very active field of drug development.

Significance of Survivin and PTEN expression in full lymph node-examined gastric cancer

AIM: To study the relationship between Survivin and PTEN expression and lymph node metastasis, depth of invasion and prognosis of gastric cancer patients in China.

METHODS: Specimens of gastric cancer tissue were collected from the Affiliated Hospital of Jianghan University. All the 140 patients had complete examination data. All lymph nodes were found by the fat-clearing method. The interrupted serial 4-micron sections, routine hematoxylin and eosin staining and immunohistochemical methods were used to detect the lymph node metastases. Gastric cancer tissue microarray was performed to test the expression of Survivin and PTEN (17A) in gastric cancer by immunohistochemical method. All data were processed using χ² test, Fisher’s exact test, Kaplan-Meyer Log-rank method and Cox multivariate analysis (SPSS 12.0 software).

RESULTS: One hundred and eighteen specimens were used in our tissue microarray (utilization rate was 82.4%). A total of 7580 lymph nodes were found. Metastases were found in 90 specimens and 1618 lymph nodes were detected. The positive rate of Survivin and PTEN expression was 52.5% (62/118) and 76.2% (90/118), respectively. A highly positive correlation was found between Survivin and PTEN expression (χ²= 4.17, P = 0.04). Survivin expression was positively correlated with UICC N stage (χ²=8.69, P=0.03) and histological classification (χ²=4.41, P=0.04) by χ² tests. PTEN expression was positively correlated with depth of invasion (P=0.02) and histological classification (χ²=5.47, P=0.02). But Survivin and PTEN expressions were not related with prognosis of gastric cancer patients. A significant correlation between lymph node metastasis and prognosis was demonstrated by Cox multivariate analysis (χ²=4.85, P=0.028).

CONCLUSION: Survivin is positively correlated with PTEN expression in gastric cancer and is a molecular marker of lymph node metastasis while PTEN expression is a molecular marker of advanced gastric cancer. UICC N stage is the most important prognostic factor of gastric cancer in China.

Targeting the cell cycle: a new approach to cancer therapy

The cell cycle represents a series of tightly integrated events that allow the cell to grow and proliferate. Critical parts of the cell cycle machinery are the cyclin-dependent kinases (CDKs), which, when activated, provide a means for the cell to move from one phase of the cell cycle to the next. The CDKs are regulated positively by cyclins and regulated negatively by naturally occurring CDK inhibitors (CDKIs). Cancer represents a dysregulation of the cell cycle such that cells that overexpress cyclins or do not express the CDKIs continue to undergo unregulated cell growth. The cell cycle also serves to protect the cell from DNA damage. Thus, cell cycle arrest, in fact, represents a survival mechanism that provides the tumor cell the opportunity to repair its own damaged DNA. Thus, abrogation of cell cycle checkpoints, before DNA repair is complete, can activate the apoptotic cascade, leading to cell death. Now in clinical trials are a series of targeted agents that directly inhibit the CDKs, inhibit unrestricted cell growth, and induce growth arrest. Recent attention has also focused on these drugs as inhibitors of transcription. In addition, there are now agents that abrogate the cell cycle checkpoints at critical time points that make the tumor cell susceptible to apoptosis. An understanding of the cell cycle is critical to understanding how best to clinically develop these agents, both as single agents and in combination with chemotherapy.

Survivin expression in breast cancer predicts clinical outcome and is associated with HER2, VEGF, urokinase plasminogen activator and PAI-1

BACKGROUND

Survivin, a novel inhibitor of apoptosis, is one of the most cancer-specific proteins identified to date. In this study we (a) evaluated the association between survivin and HER2, vascular endothelial growth factor (VEGF) and uPA/PAI-1 expression and (b) defined its effect on clinical outcome in a large breast cancer patient cohort.

PATIENTS AND METHODS

Survivin expression was measured by ELISA in primary breast cancer tissue extracts from 420 patients with long-term clinical follow-up.

RESULTS

Survivin was detected in 378 (90%) of the 420 primary breast cancer cases. Increased survivin levels were significantly associated with high nuclear grade (P < 0.0001), negative hormone receptor status (P = 0.0028), HER2 overexpression (P = 0.0094), VEGF expression (P < 0.0001), high uPA (P = 0.0002) and PAI-1 levels (P = 0.0002). Using the 25th percentile (1.4 ng/mg) as a cut-off point, patients expressing elevated survivin had a significantly worse disease-free survival (DFS: P = 0.0007, RR 1.97) and overall survival (OS: P = 0.0009, RR 2.11) compared with patients expressing lower levels of survivin. In multivariate analysis, this prognostic value of survivin was independent of both traditional and novel clinicopathologic factors for both DFS (P = 0.0076, RR 1.72) and OS (P = 0.0155, RR 1.76).

CONCLUSIONS

The independent prognostic relevance of survivin, when combined with previous data from model systems implicating survivin in the inhibition of apoptosis, suggests that survivin may be a suitable target for future therapeutic strategies.

Differential requirements for survivin in hematopoietic cell development

Although erythroid cells and megakaryocytes arise from a common progenitor, their terminal maturation follows very different paths; erythroid cells undergo cell-cycle exit and enucleation, whereas megakaryocytes continue to progress through the cell cycle but skip late stages of mitosis to become polyploid cells. In our efforts to identify genes that participate in this process, we discovered that survivin, a member of the inhibitor of apoptosis family that also has an essential role in cytokinesis, is differentially expressed during erythroid versus megakaryocyte development. Erythroid cells express survivin throughout their maturation, whereas megakaryocytes express approximately 4-fold lower levels of survivin mRNA and no detectable protein. To investigate the role of survivin in these lineages, we overexpressed or knocked down survivin from mouse bone marrow cells and then examined erythroid and megakaryocyte development. These studies revealed that overexpression of survivin antagonized megakaryocyte growth, maturation, and polyploidization but had no effect on erythroid development. This block in polyploidization was accompanied by increased expression of p21 and decreased expression of megakaryocyte genes such as von Willebrand factor and beta(1)-tubulin. In contrast, a reduction in survivin expression interfered with the formation of erythroid cells but not megakaryocytes. Last, consistent with the requirement for survivin in the survival of proliferating cells, survivin-deficient hematopoietic progenitors failed to give rise to either erythroid or megakaryocytic colonies. Together, these studies show that whereas survivin expression is essential for megakaryocyte and erythroid progenitors, its down-regulation is required for terminal differentiation of megakaryocytes.

Sustained survivin expression from OX40 costimulatory signals drives T cell clonal expansion

Sustained signaling from the T cell receptor (TCR) and costimulatory molecules is thought necessary for generating high numbers of effector T cells. Here, we show that Survivin is controlled in peripheral T cells by OX40 cosignaling via sustained PI3k and PKB activation. Survivin is induced by OX40 independent of mitotic progression in late G1, and blocking Survivin suppresses S-phase transition and division of T cells and leads to apoptosis. Moreover, Survivin expression alone is sufficient to restore proliferation and to antagonize apoptosis in costimulation-deficient T cells and can rescue T cell expansion in vivo. Survivin allows effector T cells to accumulate in large numbers, but Bcl-2 family proteins are required for T cell survival after the phase of active division. Thus, sustained Survivin expression from costimulatory signaling maintains T cell division over time and regulates the extent of clonal expansion.

New approaches and therapeutics targeting apoptosis in disease

Apoptosis, the major form of cellular suicide, is central to various physiological processes and the maintenance of homeostasis in multicellular organisms. Presumably, even more important is a causative or contributing role of apoptosis to various human diseases. These include situations with unwanted cell accumulation (cancer) and failure to eradicate aberrant cells (autoimmune diseases) or disorders with an inappropriate loss of cells (heart failure, stroke, AIDS, neurodegenerative diseases, and liver injury). The past decade has witnessed a tremendous progress in the knowledge of the molecular mechanisms that regulate apoptosis and the mediators that either prevent or trigger cell death. Consequently, apoptosis regulators have emerged as key targets for the design of therapeutic strategies aimed at modulating cellular life-and-death decisions. Numerous novel approaches are currently being followed employing gene therapy and antisense strategies, recombinant biologics, or classical organic and combinatorial chemistry to target specific apoptotic regulators. Convincing proof-of-principle evidence obtained in several animal models confirms the validity of strategies targeting apoptosis and revealed an enormous potential for therapeutic intervention in a variety of illnesses. Although numerous apoptotic drugs are currently being developed, several therapeutics have progressed to clinical testing or are already approved and marketed. Here we review the recent progress of apoptosis-based therapies and survey some highlights in a very promising field of drug development.