The influence of survivin shRNA on the cell cycle and the invasion of SW480 cells of colorectal carcinoma

Targeted anti-cancer therapy: Co-delivery of VEGF siRNA and Phenethyl isothiocyanate (PEITC) via cRGD-modified lipid nanoparticles for enhanced anti-angiogenic efficacy

Anti-tumor angiogenesis therapy, targeting the suppression of blood vessel growth in tumors, presents a potent approach in the battle against cancer. Traditional therapies have primarily concentrated on single-target techniques, with a specific emphasis on targeting the vascular endothelial growth factor, but have not reached ideal therapeutic efficacy. In response to this issue, our study introduced a novel nanoparticle system known as CS-siRNA/PEITC&L-cRGD NPs. These chitosan-based nanoparticles have been recognized for their excellent biocompatibility and ability to deliver genes. To enhance their targeted delivery capability, they were combined with a cyclic RGD peptide (cRGD). Targeted co-delivery of gene and chemotherapeutic agents was achieved through the use of a negatively charged lipid shell and cRGD, which possesses high affinity for integrin αvβ3 overexpressed in tumor cells and neovasculature. In this multifaceted approach, co-delivery of VEGF siRNA and phenethyl isothiocyanate (PEITC) was employed to target both tumor vascular endothelial cells and tumor cells simultaneously. The co-delivery of VEGF siRNA and PEITC could achieve precise silencing of VEGF, inhibit the accumulation of HIF-1α under hypoxic conditions, and induce apoptosis in tumor cells. In summary, we have successfully developed a nanoparticle delivery platform that utilizes a dual mechanism of action of anti-tumor angiogenesis and pro-tumor apoptosis, which provides a robust and potent strategy for the delivery of anti-cancer therapeutics.

Fabrication of anionic dextran-coated micelles for aptamer targeted delivery of camptothecin and survivin-shRNA to colon adenocarcinoma

In this study, we synthesized PLA-PEI micelles which was co-loaded with an anticancer drug, camptothecin (CPT), and survivin-shRNA (sur-shRNA). The hydrophobic CPT was encapsulated in the core of the polymeric micelles while sur-shRNA was adsorbed on the shell of the cationic micelles. Then, the positively-charged sur-shRNA-loaded micelles were coated with poly carboxylic acid dextran (PCAD) to form PLA/PEI-CPT-SUR-DEX. To selectively target the system to colon cancer cells, AS1411 aptamer was covalently attached to the surface of the PCAD-coated nanoparticles (PLA/PEI-CPT-SUR-DEX-APT). PLA/PEI-CPT-SUR-DEX-APT enhanced cellular uptake through receptor-mediated endocytosis followed by increased CPT accumulation, downregulation of survivin, and thereby 38% cell apoptosis. In C26 tumor-bearing mice models, after administered intravenously, PLA/PEI-CPT-SUR-DEX-APT and PLA/PEI-CPT-SUR-DEX formulations resulted in a significant inhibition of the tumor growth with tumor inhibition rate of 93% and 87%, respectively. Therefore, PLA/PEI-CPT-SUR-DEX-APT could be a versatile co-delivery vehicle for promising therapy of colorectal cancer.

Survivin promotes the invasion of human colon carcinoma cells by regulating the expression of MMP‑7

Increased expression levels of survivin are crucial for invasion activity in several types of human cancer, including colon carcinoma. However, the molecular mechanisms whereby survivin regulates cancer invasion have not been completely elucidated. To the best of our knowledge, this study is the first to investigate the role of matrix metalloprotease‑7 (MMP‑7) in cell invasion that is induced by survivin by using in vitro assays, including western blot, immunofluorescence and qPCR analyses. The results demonstrated that the ectopic expression of survivin significantly promoted the invasive activity of colon carcinoma cells (SW620 and HCT‑116) and resulted in increased levels of MMP‑7 activation. By contrast, the small interfering RNA (siRNA)‑based knockdown of survivin markedly reduced cell migration and led to a dose‑dependent decrease in MMP‑7 expression levels. Compared with the controls, knockdown of MMP‑7 by siRNA in colon carcinoma cells led to reduced invasion ability, whereas no obvious changes were observed when MMP‑7 expression was silenced in survivin‑overexpressing colon carcinoma cells. These findings demonstrate that MMP‑7 is crucial for survivin‑mediated invasiveness, suggesting that the survivin‑mediated MMP‑7 signaling pathway is a potential therapeutic target for the treatment of colon carcinoma.

A genome-wide siRNA screen reveals positive and negative regulators of the NOD2 and NF-κB signaling pathways

The cytoplasmic receptor NOD2 (nucleotide-binding oligomerization domain 2) senses peptidoglycan fragments and triggers host defense pathways, including activation of nuclear factor κB (NF-κB) signaling, which lead to inflammatory immune responses. Dysregulation of NOD2 signaling is associated with inflammatory diseases, such as Crohn's disease and Blau syndrome. We used a genome-wide small interfering RNA screen to identify regulators of the NOD2 signaling pathway. Several genes associated with Crohn's disease risk were identified in the screen. A comparison of candidates from this screen with other "omics" data sets revealed interconnected networks of genes implicated in NF-κB signaling, thus supporting a role for NOD2 and NF-κB pathways in the pathogenesis of Crohn's disease. Many of these regulators were validated in secondary assays, such as measurement of interleukin-8 secretion, which is partially dependent on NF-κB. Knockdown of putative regulators in human embryonic kidney 293 cells followed by stimulation with tumor necrosis factor-α revealed that most of the genes identified were general regulators of NF-κB signaling. Overall, the genes identified here provide a resource to facilitate the elucidation of the molecular mechanisms that regulate NOD2- and NF-κB-mediated inflammation.

OCT4 positively regulates Survivin expression to promote cancer cell proliferation and leads to poor prognosis in esophageal squamous cell carcinoma

Background

OCT4 and Survivin are important factors for cancer cell proliferation, renewal and dedifferentiation, and correlate with resistance to radiotherapy and chemotherapy in most human cancers, but their regulatory mechanisms are not well known.

Methodology/Principal Findings

In this study, 50 patients with esophageal squamous cell carcinoma (ESCC) were retrospectively analyzed. OCT4 was expressed in 13 cases (26%), and survivin was positively expressed in 31 cases (62%), examined by immunochemistry. OCT4 was found to be an independent predictive factor for median survival time, and the patients from the subgroup with both high expression of OCT4 and Survivin had the worst prognosis investigated by log-rank test. To further explore the molecular regulatory mechanism between OCT4 and Survivin, we constructed the specific small hairpin RNA (shRNA)-expressing vectors targeting OCT4 or/and Survivin and manipulated the expression of OCT4 and Survivin. By Western blotting and RT-PCR, we found that OCT4 could up-regulate Survivin expression in the esophageal cancer cell lines Eca109 and TE1. Simultaneously knockdown of OCT4 and Survivin expression induced cell apoptosis and G2-phase decrease of cell cycle by flow cytometry, and finally exerted an enhanced anti-proliferation potency in Eca109 and TE1 cell lines by MTT assay.

Conclusions

This study shows that OCT4 and Survivin expression were correlated with poor survival in patients with ESCC. OCT4 and Survivin may be regarded as targets in ESCC biotherapy.

AMPK inhibitor compound C suppresses cell proliferation by induction of apoptosis and autophagy in human colorectal cancer cells

BACKGROUND AND OBJECTIVES

AMP-activated protein kinase (AMPK) is a main regulator of energy metabolism through the inhibition of biosynthetic pathways and enhancement of ATP-generating pathways. However, targeting AMPK as anti-tumor therapy remains controversial. In this study, we examined the effect of compound C, a small molecule inhibitor of AMPK, on the proliferation of several human colorectal cancer cell lines with diverse characteristics.

METHODS

Four human colorectal cancer cell lines (HCT116, DLD-1, SW480, and KM12C) were treated with compound C. Cell viability was determined by MTS assay. Cell cycle prolife was analyzed by flow cytometry. Acidic vesicular organelles were detected by acridine orange staining. Protein levels were measured by western blotting.

RESULTS

Compound C inhibited the growth of four cell lines in a dose-dependent manner and caused G(2) /M arrest. Compound C increased sub-G(1) cell population and induced chromatin condensation and cleavage of PARP in HCT116 and KM12C cells, while it induced acidic vesicular formation and conversion of LC3-I to autophagosome-associated LC3-II in DLD-1 and SW480 cells. Survivin, an anti-apoptotic protein, was down-regulated in all cell lines treated with compound C.

CONCLUSIONS

Compound C induces apoptotic or autophagic death in colorectal cancer cells and the preferred death mode is cell type-dependent.

Four-component synthesis of 1,2-dihydropyridine derivatives and their evaluation as anticancer agents

Two series of compounds with the general formula of 4,6-diaryl-2-oxo-1,2 dihydropyridine-3-carbonitriles and their isosteric imino derivatives were synthesized through a one pot reaction of acetophenone, aldehyde and ammonium acetate with ethyl cyanoacetate or malononitrile, respectively. The synthesized compounds were evaluated for tumor cell growth inhibitory using the human HT-29 colon and MDA-MB-231 breast tumor cell lines. Compound 4-(2- Ethoxyphenyl)-2-imino-6-(4-fluorophenyl)-1,2-dihydropyridine-3 carbonitrile (6) showed IC50 value of 0.70 μM versus HT-29. Meanwhile, compound 4-(2-Hydroxyphenyl)-2-imino-6-(4-fluorophenyl)-1,2-dihydropyridine-3-carbonitrile (4) showed IC50 value of 4.6 μM versus MDA-MB-231. Docking compound 10 to possible molecular targets, survivin and PIM1 kinase showed appreciable interactions with both, which suggest possible targets for the antitumor activity of this novel class of anticancer compounds.

Tithonia diversifolia and its main active component tagitinin C induce survivin inhibition and G2/M arrest in human malignant glioblastoma cells

We investigated the antitumour activity of Tithonia diversifolia (TD) on malignant glioblastoma cells. Our results suggested that tagitinin C was the main component in viability inhibition on malignant glioblastoma cells, and also accounted to be the most abundant component (>65%) in TD extract. Both TD extract and tagitinin C exhibited vigorous potential to produce in vitro viability inhibition, autophagic cell death and G2/M arrest. Furthermore, the activity of survivin, a critical resistant-factor in cancer therapy, could be downregulated significantly by TD extract and tagitinin C. These findings suggested that TD extract and tagitinin C were effective for treating malignant glioblastoma.

Insights on distinct pathways of thiazolidinediones (PPARgamma ligand)-promoted apoptosis in TRAIL-sensitive or -resistant malignant urothelial cells

Thiazolidinediones, including rosiglitazone and troglitazone, are insulin-sensitizing drugs and high-affinity ligands for the peroxisome proliferator-activated receptor gamma (PPARgamma). Apart from their antidiabetic activity, these molecules possess antitumor properties. We investigated their potential apoptotic effects on RT4 (derived from a well-differentiated Grade I papillary tumor) and T24 (derived from an undifferentiated Grade III carcinoma) bladder cancer cells. Rosiglitazone induced G2/M or G0/G1 phase cell cycle arrest in RT4 and T24 cells, respectively. Only troglitazone triggered apoptosis via extrinsic and intrinsic pathways in both cell lines. Interestingly, rosiglitazone amplified TRAIL-induced apoptosis in TRAIL-sensitive RT4 cells or let TRAIL-resistant T24 cells to respond to TRAIL. Thiazolidinediones acted through PPARgamma activation-independent mechanisms. The underlying mechanisms involved for the first time in cancer cells the upregulation of soluble and/or membrane-bound TRAIL. This was associated with increased cell surface death receptor 5 expression and c-FLIP and survivin downregulation, mediated in part through proteasome-dependent degradation in troglitazone-promoted cell death. Therefore, the combination of rosiglitazone and TRAIL could be clinically relevant as chemopreventive or therapeutic agents for the treatment of TRAIL-resistant high-grade urothelial cancers.

Discovery of colon tumor cell growth inhibitory agents through a combinatorial approach

Two series with the general formula of 4,6-diaryl-2-oxo-1,2 dihydropyridine-3-carbonitriles and their isosteric 4,6-diaryl-2-imino-1,2-dihydropyridine-3-carbonitrile were synthesized through one pot reaction of the appropriate acetophenone, aldehyde, ammonium acetate with ethyl cyanoacetate or malononitrile, respectively. The synthesized compounds were evaluated for their tumor cell growth inhibitory activity against the human HT-29 colon tumor cell line, as well as their PDE3 inhibitory activity. Compound 4-(2-Ethoxyphenyl)-2-oxo-6-thiophen-3-yl-1,2-dihydropyridine-3 carbonitrile (21) showed tumor cell growth inhibitory activity with an IC50 value of 1.25 microM. Meanwhile, 4-(4-Ethoxyphenyl)-2-imino-6-(thiophen-3-yl)-1,2-dihydropyridine-3-carbonitrile (26) showed inhibitory effect upon PDE3 using cAMP or cGMP as substrate. No correlation exists between PDE3 inhibition and the tumor cell growth inhibitory activity. Docking compound 21 to other possible molecular targets showed the potential to bind PIM1 Kinase.

Endogenous survivin modulates survival and proliferation in UVB-treated human keratinocytes

Survivin is a bi-functional member of inhibitor of apoptosis protein family, as it is able to both inhibit apoptosis and to regulate cell cycle. We investigated the role of survivin in human keratinocytes under normal conditions and during UVB irradiation. Survivin siRNA decreases proliferation and induces apoptosis in human keratinocytes, in a mode consistent with the mitotic catastrophe. Low doses UVB increase survivin expression at earlier times, while high doses down-regulate survivin level. Low doses UVB induce cell cycle arrest in G2/M, while high doses UVB cause apoptosis. Moreover, overexpression of survivin protects keratinocytes from UVB-induced apoptosis, and silencing of survivin renders keratinocytes more susceptible to UVB-induced cell death. Finally, survivin siRNA increases UVB-induced reduction of cell proliferation. Taken together, these results indicate that survivin plays a critical role in epidermal homeostasis in normal conditions and during UVB exposure, with possible implication in skin carcinogenesis.