Bifunctional roles of survivin-ΔEx3 and survivin-2B for susceptibility to apoptosis in endometrial carcinomas

Potential anticancer properties of calotropis procera: An investigation on breast and colon cancer cells

Calotropis procera is a perennial flowering plant of the Apocynaceae family, traditionally used in medicine to treat various ailments. Recent investigations have revealed its potential therapeutic activities such as anti-inflammatory, gastroprotective, analgesic, anti-obesity, and anti-diabetic properties. RP-HPLC qualitatively and quantitatively evaluated the phenolic acids and flavonoids in the ethanolic extract at two different wavelengths, 280 and 330 nm. In addition, total phenolic and flavonoid contents were measured via spectrophotometric determination in addition to the antioxidant activity. The antiproliferative effects of C. procera were investigated on two cancer cell lines: human colon (HCT-116) and breast (MCF-7) cancer. Several methods were utilised to analyse the effectiveness of the plant extract on the cytotoxicity, apoptosis, cell cycle progression, genes involved in the cell cycle, and protein expression profiles of HCT-116 and MCF-7 cells. These included the MTT assay, Annexin V-FITC/PI, analysis of the cell cycle, and Western blot. Results indicated that ferulic and caffeic acids were the major compounds at λ_max 280 nm (1.374% and 0.561%, respectively), while the major compounds at λ_max 325 nm were kaempferol and luteolin (1.036% and 0.512%, respectively). The ethanolic extract had significantly higher antioxidant activity (80 ± 2.3%) compared to ascorbic acid (90 ± 3.1%). C. procera extract exhibited dose-dependent cell growth inhibition, with an estimated IC₅₀ of 50 μg/mL for MCF-7 and 55 μg/mL for HCT-116 cells at 24 h. Annexin V-FITC/PI confirmed the induction of apoptosis. Remarkably, cell cycle arrest occurred at the sub-G1 phase in MCF-7 cells, while in HCT-116 cells, it was observed at the G2-M phase. The sub-G1 arrest was associated with dysregulation of Akt, p-AKT, mTOR, and p-mTOR proteins, as confirmed by the Western blot analysis, while downregulation of CDK1, cyclin B1, and survivin caused G2-M arrest.

The inhibitory effect and safety of GANT61 on HeLa cells in nude mice

The Hedgehog (Hh) pathway effector Gli1 plays an important role in cervical cancer, and GANT61 is an Hh signaling inhibitor. In this study, we aimed to investigate the inhibitory effect of GANT61 on cervical cancer and to study its safety in nude mice. We used in vivo experiments to assess the effect of GANT61 on the growth of cervical cancer HeLa cells, and we measured the WBC, HGB, PLT, ALT, AST and Cre levels in nude mice. Next, we examined the organ and tumor morphology and distant metastasis by HE staining. We used immunohistochemistry to monitor the expression levels of Gli1, FoxM1, Ki-67, cyclinD1, E-cadherin, vimentin, survivin, caspase-3 and CD34+. Western blotting and RT-RCR were used to measure Gli1 expression. GANT61 inhibited the growth and metastasis of HeLa cervical cancer cells upon their transplantation into nude mice, and we preliminarily propose that GANT61 is safe for nude mice. These findings suggest that GANT61 could be used as a Hedgehog inhibitor to inhibit EMT and proliferation and to promote apoptosis via Gli1 downregulation.

Survivin as a novel target protein for reducing the proliferation of cancer cells

Survivin, also known as baculoviral inhibitor of apoptosis repeat-containing 5, is a novel member of the inhibitor of apoptosis protein family. Survivin is highly expressed in tumors and embryonic tissues and is associated with tumor cell differentiation, proliferation, invasion and metastasis; however, survivin is expressed at low levels in normal terminally differentiated adult tissues. Meanwhile, the expression level of survivin is also a negative prognostic factor for patients with cancer. These unique characteristics of survivin make it an exciting potential therapeutic target for cancer treatment. This review will discuss the biological characteristics of survivin and its potential use as a treatment target to reduce cancer cell proliferation.

Differential Impacts of Alternative Splicing Networks on Apoptosis

Apoptosis functions as a common mechanism to eliminate unnecessary or damaged cells during cell renewal and tissue development in multicellular organisms. More than 200 proteins constitute complex networks involved in apoptotic regulation. Imbalanced expressions of apoptosis-related factors frequently lead to malignant diseases. The biological functions of several apoptotic factors are manipulated through alternative splicing mechanisms which expand gene diversity by generating discrete variants from one messenger RNA precursor. It is widely observed that alternatively-spliced variants encoded from apoptosis-related genes exhibit differential effects on apoptotic regulation. Alternative splicing events are meticulously regulated by the interplay between trans-splicing factors and cis-responsive elements surrounding the regulated exons. The major focus of this review is to highlight recent studies that illustrate the influences of alternative splicing networks on apoptotic regulation which participates in diverse cellular processes and diseases.

Alternative RNA splicing and gastric cancer

Alternative splicing (AS) linked to diseases, especially to tumors. Recently, more and more studies focused on the relationship between AS and gastric cancer (GC). This review surveyed the hot topic from four aspects: First, the common types of AS in cancer, including exon skipping, intron retention, mutually exclusive exon, alternative 5 ' or 3' splice site, alternative first or last exon and alternative 3' untranslated regions. Second, basic mechanisms of AS and its relationship with cancer. RNA splicing in eukaryotes follows the GT-AG rule by both cis-elements and trans-acting factors regulatory. Through RNA splicing, different proteins with different forms and functions can be produced and may be associated with carcinogenesis. Third, AS types of GC-related genes and their splicing variants. In this paper, we listed 10 common genes with AS and illustrated its possible molecular mechanisms owing to genetic variation (mutation and /or polymorphism). Fourth, the splicing variants of GC-associated genes and gastric carcinogenesis, invasion and metastasis. Many studies have found that the different splicing variants of the same gene are differentially expressed in GC and its precancerous diseases, suggesting AS has important implications in GC development. Taking together, this review highlighted the role of AS and splicing variants in the process of GC. We hope that this is not only beneficial to advances in the study field of GC, but also can provide valuable information to other similar tumor research.Although we already know some gene splicing and splicing variants play an important role in the development of GC, but many phenomena and mechanisms are still unknown. For example, how the tumor microenvironment and signal transduction pathway effect the forming and function of AS? Unfortunately, this review did not cover the contents because the current study is limited. It is no doubt that clarifying the phenomena and mechanisms of these unknown may help to reveal the relationship of AS with complex tumor genetic variation and the occurrence and development of tumors.

Silencing of Survivin Expression Leads to Reduced Proliferation and Cell Cycle Arrest in Cancer Cells

Survivin is an anti-apoptotic gene that is overexpressed in most human tumors. RNA interference using short interfering RNA (siRNA) can be used to specifically inhibit survivin expression. Tumor cells were treated with a newly designed survivin siRNA, which was modified with 2′-OMe. Cellular survivin mRNA and protein levels were determined by real-time qRT-PCR and Western blot, respectively. Cell cycle and apoptosis were determined by flow cytometry. Cell proliferation was measured by MTT assay. Our data showed that the novel survivin-targeted siRNA could efficiently knockdown the expression of survivin and inhibit cell proliferation. Survivin mRNA was reduced by 95% after 48h treatment with 20nM siRNA. In addition, the siRNA could markedly arrest the cell cycle at the G2/M checkpoint and induce cellular apoptosis in a dose-dependent manner. The percentage of apoptotic cells reached 50% when treated with 40nM siRNA. In conclusion, we have identified a novel chemically modified siRNA against survivin that is highly efficient and delineated its mechanism of action, thus demonstrating a potential therapeutic role for this molecule in cancer. Further evaluation of this siRNA for therapeutic activity is warranted.

Transcriptional upregulation of HNF-1β by NF-κB in ovarian clear cell carcinoma modulates susceptibility to apoptosis through alteration in bcl-2 expression

Hepatocyte nuclear factor-1β (HNF-1β) is a transcriptional factor that has an important role in endometriosis-ovarian clear cell carcinoma (OCCC) sequence by modulating cell kinetics and glucose metabolism. However, little is known about the detailed molecular mechanisms that govern its regulation and function. Herein, we focus on upstream and downstream regulatory factors of HNF-1β in OCCCs. In clinical samples, HNF-1β expression was positively correlated with the active form of NF-κB/p65 in OCCCs, and closely linked with a low nuclear grade and non-solid architecture. In cell lines, transfection of p65 resulted in increased HNF-1β mRNA and protein expression in TOV-21G cells (OCCC cell line with endogenous HNF-1β expression), in line with activation of the promoter, probably through interacting with the basic transcriptional machinery. Suppression of endogenous HNF-1β expression by siRNA increased apoptosis in TOV-21G cells, while treatment of Hec251 cells (endometrial carcinoma cell line with extremely low endogenous HNF-1β expression) stably overexpressing exogenous HNF-1β with doxorubicin abrogated apoptosis of the cells, along with increased ratio of bcl-2 relative to bax. Moreover, overexpression of HNF-1β led to upregulation of bcl-2 expression at the transcriptional level in TOV-21G cells, which provided evidence for a positive correlation between HNF-1β and bcl-2 expression in OCCCs. These data, therefore, suggest that association between HNF-1β and NF-κB signaling may participate in cell survival by alteration of apoptotic events, particularly in mitochondria-mediated pathways, through upregulation of bcl-2 expression in OCCCs.

High expression of survivin and its splice variants survivin ΔEx3 and survivin 2 B in oral cancers

OBJECTIVES

We have previously reported inactivation of p53 in 46% of Indian patients with oral cancer. Survivin, a p53 target gene and an inhibitor of apoptosis protein (IAP), is overexpressed in several cancers, including oral cancers. Studies assessing the role of survivin and its splice variants in oral cancers are, however, rare.

MATERIALS AND METHODS

The expression of 6 survivin isoforms in 4 oral cancer cell lines (AW8507, AW13516, UPCI-SCC040, UPCI-SCC029 B), a dysplastic oral cell line (DOK), 75 paired oral tumor and adjacent normal tissues, and 12 normal oral tissue samples from healthy individuals was analyzed by real-time PCR. The expression was correlated with clinicopathologic parameters, which included age, sex, tumor-node-metastasis (TNM) staging, tobacco and/or alcohol consumption, site, and differentiation status of tumor.

RESULTS

This is the first study to find overexpression of the 6 characterized survivin isoforms in oral cancers compared with normal tissues (P < .05). Additionally, a significant (P < .05) correlation among the fold changes of all 6 survivin isoforms was observed. Survivin wild type (wt) was the predominantly expressed isoform in oral cell lines and tumor tissues versus normal tissues (P < .05). Among the minor isoforms, survivin ΔEx3 and survivin 2 B were dominantly expressed, whereas survivin 2 α and survivin 3 α overexpression was found for the first time. Further high survivin 3 B expression exhibited a significant association (P < .05) with poorly differentiated tumors. Interestingly the combined expression of the antiapoptotic survivin isoforms, survivin wt, survivin ΔEx3, and survivin 3 B, exhibited a significant association with TNM staging of the tumor.

CONCLUSIONS

Our studies thus indicate that oral cancers overexpress the antiapoptotic survivin variants, which exhibit an association with advanced tumor stage, implying a role for these variants in oral tumorigenesis.

Hypoxia-mediated cancer stem cells in pseudopalisades with activation of hypoxia-inducible factor-1α/Akt axis in glioblastoma

Pseudopalisades (Ps) around necrotic foci are severely hypoxic and overexpress hypoxia-inducible factor (HIF) in glioblastoma (GBM). Hypoxic regions have been proposed as one of several distinct niches for cancer stem cells (CSCs) in GBM, but little is known about the association between Ps features and CSC properties. Herein, we focused on the biological role of Ps lesions. In clinical cases of GBM, expression of hypoxia-related molecules including HIF-1α, Glut-1, p27(Kip1), and pAkt was significantly increased in perinecrotic Ps lesions compared with nonnecrotic areas and perinecrotic lesions lacking Ps features. Significantly higher expression levels of several CSC-related markers, including CD133, Sox2, CD44s, and aldehyde dehydrogenase (ALDH) 1, were also observed in Ps lesions, which were positively correlated with expression of hypoxia-related molecules and pAkt. Ps lesions also showed increased number of apoptotic cells and decreased bcl-2 and survivin expression compared with the surrounding tissue. Short-term exposure of astrocytoma cell lines to cobalt chloride, which is known to mimic the effect of hypoxia, caused an increase in expression of both hypoxia- and CSC-related markers, in line with increases in the ALDH(high) cell population and number of spheroids. Inhibition of endogenous Akt by LY294002 resulted in decreased expression of Sox2, ALDH1, and CD133, leading to enhancement of cobalt chloride-mediated apoptotic events due to altered ratio of bcl-2 to bax expression. These findings suggest that Ps lesions within GBM may serve as a specialized hypoxic niche, in which the HIF-1α/pAkt axis is activated, in response to severe hypoxia.