RNAi targeting STMN alleviates the resistance to taxol and collectively contributes to down regulate the malignancy of NSCLC cells in vitro and in vivo.

Stathmin (STMN) plays a vital role in maintaining the malignant behavior of cancer through directly regulating microtubule dynamics equilibrium. Taxol, an effective chemotherapeutics mainly acting to promote microtubule polymerization, has been commercially applied in treating solid tumors, which results in serious drug resistance. Our study demonstrated that STMN RNA interference (RNAi) enlarged taxol-induced inhibitions in cellular proliferation, colony formation, and multidimensional spaces of cell immigration and decreased half maximal inhibitory concentration (IC50) of taxol in nonsmall cell lung cancer (NSCLC) NCI-H1299 cells; STMN RNAi and taxol jointly attenuated the expressions of extracellular regulated kinase (ERK), nuclear factor kappa B (NF-κB) and B cell lymphoma-2 (Bcl-2), but up regulated Bax expression and initiated intrinsic cell death pathway by activating caspase-3 and caspase-9, while inhibited interleukin 10 (IL-10) autocrine from cell culture supernatant and xenografted mouse serum, as well as intracellular expressions of IL-10 protein and mRNA in vitro; additionally, neutralizing IL-10 alone would incur cell apoptosis to some degree; the further study confirmed that RNAi targeting STMN promoted the sensitivity of taxol in different NSCLC cells. In vivo animal experiments proved that STMN RNAi and taxol cooperatively inhibited the tumorigenicity of NCI-H1299 cells and histological atypia and Ki-67 proliferative index of xenografted tumors and promoted cell differentiation to a higher grade with well-differentiated indicators of glandular lumen-like structure and proliferative fibroblasts. These findings suggest that silencing STMN alleviates the resistance to taxol and collectively contributes to induce the dysfunction of multiple signals and down regulate the malignancy of tumors; thus, STMN is a promising target in treating refractory tumors.

Epstein-Barr virus-encoded LMP1 triggers regulation of the ERK-mediated Op18/stathmin signaling pathway in association with cell cycle.

The MAPKs are activated by a variety of cellular stimuli to participate in a series of signaling cascades and mediate diverse intracellular responses. One potential target of the MAPKs is Op18/stathmin, a molecule that acts as an integrator of diverse cell signaling pathways and regulates the dynamics of microtubules, which are involved in modulating a variety of cellular processes, including cell cycle progression and cell growth. Our study focused on the regulation of the MAPK-mediated Op18/stathmin signaling pathway, which is triggered by the Epstein-Barr virus-encoded latent membrane protein 1 ( LMP1) oncogene in nasopharyngeal carcinoma cells. The results showed that the activity of MAPK, which was induced by LMP1, varied with cell cycle progression; LMP1 upregulated phosphorylation of ERK during the G(1)/S phase, but negatively regulated phosphorylation of ERK during the G(2)/M phase. We found that the regulation of Op18/stathmin signaling by LMP1 was mainly mediated through ERK. The inhibition of LMP1 expression attenuated the interaction of ERK with Op18/stathmin and promoted microtubule depolymerization. These findings indicate the existence of a new cell cycle-associated signaling pathway in which LMP1 regulates ERK-mediated Op18/stathmin signaling.

EBV-encoded LMP1 regulates Op18/stathmin signaling pathway by cdc2 mediation in nasopharyngeal carcinoma cells.

Oncoprotein 18/stathmin (Op18/stathmin) plays a crucial role in maintaining cell biological characteristics by regulating microtubule dynamics, especially entry into mitosis; phosphorylated Op18/stathmin promotes microtubule polymerization to form the mitotic spindle, which is essential for chromosome segregation and cell division. Cdc2 is a critical kinase in starting M phase events in cell-cycle progression and is a positive regulator of the cell cycle. Latent membrane protein 1 (LMP1) is an Epstein-Barr virus (EBV)-encoded oncogenic protein that is able to induce carcinogenesis via various signaling pathways. This study focused on regulation by LMP1 of Op18/stathmin signaling in nasopharyngeal carcinoma (NPC) cells and showed that LMP1 regulates Op18/stathmin signaling through cdc2 mediation, LMP1 upregulates cdc2 kinase activity, and Op18/stathmin phosphorylation promotes the interaction of cdc2 with Op18/stathmin and microtubule polymerization during mitosis, and inhibition of LMP1 expression attenuates the interaction of cdc2 and Op18/stathmin and promotes microtubule depolymerization. These results reveal a new pathway via which LMP1 regulates Op18/stathmin signaling by cdc2 mediation; this new signaling pathway not only perfects the LMP1 regulation network but also elucidates the molecular mechanism of LMP1 that leads to carcinogenesis.

Introduction of exogenous wild­type p53 mediates the regulation of oncoprotein 18/stathmin signaling via nuclear factor­κB in non­small cell lung cancer NCI­H1299 cells.

Our previous studies demonstrated that high expression of oncoprotein 18 (Op18)/stathmin promotes malignant transformation of non­small cell lung cancer NCI­H1299 cells. Investigation of the cellular settings determined that NCI­H1299 cells were genetically p53 deficient. In order to determine whether p53 deficiency is associated with Op18/stathmin­mediated high levels of malignancy, exogenous wild­type p53 (p53wt) was introduced into NCI­H1299 cells in the present study to observe Op18/stathmin signaling changes and malignant behaviors. The results indicated that p53 downregulated Op18/stathmin expression and phosphorylation at the Ser25 and Ser63 sites in NCI­H1299 cells, and the abilities of proliferation, colony formation and migration in multi­dimensional spaces were simultaneously reduced. Introduction of p53wt inhibited the expression of the transcription factor nuclear factor­κB (NF­κB), and the activities of the Op18/stathmin upstream kinases cyclin­dependent 2 (CDC2) and extracellular signal­regulated kinase (ERK). Furthermore, blocking of NF­κB signaling decreased CDC2 and ERK activation. Additionally, p53 intervention attenuated the secretion and protein expression of the immune inhibitory cytokine interleukin­10, which was in accordance with the effect of NF­κB signaling inhibition. Further experiments validated that p53 enhanced the sensitivity of NCI­H1299 cells to Taxol through initiating the caspase­3 and ­9 intrinsic death pathways, and resulted in cell cycle arrest at the G1/S phases. These data indicated that exogenous p53wt mediates the regulation of Op18/stathmin signaling through the p53­NF­κB­CDC2/ERK­Op18/stathmin pathway, and that p53 deficiency is associated with high malignancy levels of NCI­H1299 cells.

In vitro neutralization of autocrine IL­10 affects Op18/stathmin signaling in non­small cell lung cancer cells.

Our previous studies have identified that silencing oncoprotein 18 (Op18)/stathmin via RNA interference (RNAi) inhibited autocrine interleukin­10 (IL­10) and enhanced the sensitivity to Taxol in NCI­H1299 non­small cell lung cancer cells. In this study, whether autocrine IL­10 regulates Op18/stathmin signaling in NCI­H1299 cells was examined by neutralizing IL­10 using a targeted antibody. In vitro neutralization of IL­10 by anti­IL­10 antibody impaired the capacities of the NCI­H1299 cells to proliferate, form colonies and migrate. Furthermore, the expression levels of caspase­3 and ­8, and sensitivity to Taxol were increased. Neutralizing IL­10 downregulated Op18/stathmin expression and its phosphorylation at Ser25 and Ser63 sites, and suppressed the activities of upstream kinases, extracellular signal­regulated kinase (ERK) and cyclin­dependent kinase 1 (CDK1). In addition, neutralizing IL­10 also reduced the expression levels of the transcription factor nuclear factor­κB (NF­κB) and phosphorylation of its active subunit, p65 (Ser536). Furthermore, blocking NF­κB signaling with PDTC also decreased the activities of ERK and CDC2 kinases, and decreases levels of autocrine released IL­10 and its protein expression. Additionally, knocking down Op18/stathmin by RNAi reduced the expression levels of NF­κB and IL­10. Further animal experiments revealed that the number of neutrophils, lymphocytes and monocytes were all decreased in the blood of tumor­bearing mice with NCI­H1299 cell xenografts. Thus, the data suggested that autocrine IL­10 regulates Op18/stathmin signaling via an IL­10­NF­κB­ERK/CDC2 axis, which regulates the malignant behaviors of NCI­H1299 cells. A feedback regulation also exists between Op18/stathmin and autocrine IL­10 signaling pathways in non­small cell lung cancer cells.

Schistosoma japonicum: protective immunity induced by schistosomulum-derived cells in a mouse model.

We previously reported that immunization with intact live cells from schistosomula of Schistosoma japonicum (S.j) partially protected the Kunming strain of mice from challenge infection. In the present work, 2 immune protective experiments were designed to further validate the protective effect induced by this type of vaccine and to optimize the immunization protocol, including the number of inoculations and parasite stages from which immunogenic cells were derived. Three antigens derived from 18-day-old postinfection live (LLC) and dead (DLC) larval worm cells and from dead 42-day-old postinfection adult worm cells (DAC) were used as immunogens. Our results demonstrate that live cells from 18-day-old worms are capable of inducing significant protection in mice using a murine-Sj challenge model as shown by reduction rates of worm recoveries and egg burdens. The development of adult worms was stunted. A Th1-biased immune response was reflected in the protected groups as evidenced by the ratio of IgG2a/IgG1. A 38-kDa polypeptide was recognized by sera from LLC immunized animals. We demonstrate that live parasite cells are a source of novel protective antigens that can be exploited for vaccine development.

The Cdc2/Cdk1 inhibitor, purvalanol A, enhances the cytotoxic effects of taxol through Op18/stathmin in non-small cell lung cancer cells in vitro.

Purvalanol A is a highly selective inhibitor of Cdc2 [also known as cyclin-dependent kinase 1 (CDK1)]. Taxol is an anti-tumor chemotherapeutic drug which is widely used clinically. In this study, the CDK1 inhibitor, purvalanol A was applied to explore the relevance of Cdc2 signaling and taxol sensitivity through analyses, such as cellular proliferation and apoptosis assays, ELISA, western blot analysis and immunoprecipitation. We demonstrated that purvalanol A effectively enhanced the taxol-induced apoptosis of NCI-H1299 cells, as well as its inhibitory effects on cellular proliferation and colony formation. In combination, purvalanol A and taxol mainly decreased the expression of oncoprotein 18 (Op18)/stathmin and phosphorylation at Ser16 and Ser38, while purvalanol A alone inhibited the phosphorylation of Op18/stathmin at all 4 serine sites. Co-treatment with purvalanol A and taxol weakened the expression of Bcl-2 and activated the extrinsic cell death pathway through the activation of caspase-3 and caspase-8. Further experiments indicated that Cdc2 kinase activities, including the expression of Cdc2 and the level of phospho-Cdc2 (Thr161) were significantly higher in taxol-resistant NCI-H1299 cells compared with the relatively sensitive CNE1 cells before and following treatment with taxol. These findings suggest that Cdc2 is positively associatd with the development of taxol resistance. The Cdc2 inhibitor, purvalanol A, enhanced the cytotoxic effects of taxol through Op18/stathmin. Our findings may prove to be useful in clinical practice, as they may provide a treatment strategy with which to to reduce the doses of taxol applied clinically, thus alleviating the side-effects.

Vinblastine differs from Taxol as it inhibits the malignant phenotypes of NSCLC cells by increasing the phosphorylation of Op18/stathmin.

Taxol (paclitaxel) and vinblastine (VBL) are both efficacious chemotherapeutic agents that target the microtubules of tumor cells, but each functions in a mutual antagonistic manner. Op18/stathmin is a small molecular phosphoprotein which promotes depolymerization of microtubules. Non-small cell lung cancer (NSCLC) NCI-H1299 cells were employed to compare the curative effects of VBL and Taxol and explore the correlation between drug sensitivity and Op18/stathmin signaling. The present study found that VBL obviously promoted cellular apoptosis and initiated activation of caspase 3 and 9, and inhibited cell proliferation and colony formation, as well as cell migration in the NCI-H1299 cells in contrast with Taxol. VBL did not affect the expression of Op18/stathmin, but increased its phosphorylation at all 4 serine sites. Conversely, Taxol mainly decreased the expression of Op18/stathmin and the phosphorylation at Ser25 and Ser63 sites. Silencing of Op18/stathmin by RNA interference (RNAi) led to a great reduction in the differences in the cell proliferation inhibition between VBL and Taxol. VBL treatment notably weakened the expression of PP2A, Bcl-2, NF-κB and interleukin-10 (IL-10) and autocrine IL-10 compared with Taxol; whereas PP2A was substantially increased following Taxol induction. High expression of Op18/stathmin was found to be negatively correlated with the sensitivity of Taxol in the NSCLC cells, but had a minor impact on VBL cytotoxicity. These findings revealed that both VBL and Taxol induce cell apoptosis through Op18/stathmin, but the mechanisms are completely different. VBL is an attractive alternative to the treatment of Taxol-resistant tumors with high expression of Op18/stathmin.

Regulation of Oncoprotein 18/Stathmin Signaling by ERK Concerns the Resistance to Taxol in Nonsmall Cell Lung Cancer Cells.

Taxol is a cytotoxic antiepithelioma chemotherapy drug widely used clinically, which results in appearing a broad range of taxol-resistant tumors. Oncoprotein 18 (Op18)/stathmin is a genetically highly conserved small-molecule cytosolic phosphoprotein and highly expressed in tumors. Extracellular signal-regulated kinase (ERK) is a main member of mitogen-activated protein kinases (MAPKs). The study demonstrated that combination of blockage of ERK signal by ERK inhibitor PD98059 and Taxol greatly promoted taxol-induced cellular apoptosis and growth inhibition, decreased the expression of Op18/stathmin and total levels of phosphor-Op18/stathmin, while weakened the cyclin-dependent kinase 2 (cdc2) activity and antiapoptotic protein Bcl-2 expression and inhibited IL-10 autocrine in taxol-resistant NCI-H1299 cells; Taxol-resistant NCI-H1299 cells expressed high levels of ERK and phosphor-ERK in contrast to taxol-sensitive CNE1 cells, and ERK mainly phosphorylated Op18/stathmin at Ser 25 site. These findings suggest that ERK-mediated Op18/stathmin is involved in taxol resistance of tumors; blockage of ERK signal improves the sensitivity of tumor cells to taxol, which provides new clues for treating taxol-resistant carcinomas.

Silencing Op18/stathmin by RNA Interference Promotes the Sensitivity of Nasopharyngeal Carcinoma Cells to Taxol and High-Grade Differentiation of Xenografted Tumours in Nude Mice.

Nasopharyngeal carcinoma (NPC) is a refractory tumour, and chemotherapy is one of the primary treatment modalities. Oncoprotein 18 (Op18)/stathmin is a conserved small cytosolic phosphoprotein and highly expressed in tumours, which plays a vital role in maintaining the malignant phenotype of tumours. Taxol is a clinically widely used chemotherapeutic agent for a broad range of taxol-resistant tumours. This study showed that Op18/stathmin silencing by RNA interference (RNAi) combined taxol cooperatively improved cellular apoptosis in CNE1 cells mainly via initiating endogenous death receptor pathway, impaired the capabilities of cellular proliferation and cellular migration and down-regulated the half maximal inhibitory concentration (IC50 ) of taxol, meanwhile decreased the expression of the upstream extracellular regulated kinase 1 (ERK1) in vitro. Evidence also showed that taxol cytotoxicity was markedly augmented for Op18/stathmin RNAi in other NPC cells. In vivo animal experiments have demonstrated that early combination of Op18/stathmin silencing and taxol evidently inhibited tumourigenicity of CNE1 cells and growth of xenografted tumours in nude mice. Remarkably, silencing Op18/stathmin by RNAi still promoted transformation of late-stage CNE1 cells in NPC-xenografted tumours from moderately to highly differentiated and inhibited the pleiotropic cytokine interleukin-10 (IL-10) autocrine by transplanted tumours. These findings suggest that silencing Op18/stathmin by RNAi promotes chemosensitization of NPC to taxol and reverses malignant phenotypes of NPC, which provides a new clue for treating drug-resistant tumours.

[Identification of the source and types of cells of Schistosoma japonicum by histochemical staining].

OBJECTIVE: To study the possibility on in vitro identifying the source or kinds of cells from Schistosoma japonicum (S.j). METHODS: The cells from digested tissues of 18 days old schistosomula were smeared on slides. The adult worms of S.j were used for making paraffin sections. The cell smears and tissue sections were stained with 6 different methods of histochemical staining including Periodic Acid-Schiff (PAS), Argyrophil reaction (by Grimeliu's), Picric acid-acid Fuchsin (by Van Gieson, VG), Thionin, Toluidine blue (TB) and Hematoxylin-Eosin (HE) staining parallelly. The results were judged through inspecting the specific color of the cells on smears referring to location of corresponding staining of paraffin sections of adult worm tissues under light microscopy. RESULTS: Vitelline gland cells, mother germ cells, nerve cells, digestive epithelial cells, muscular cells and mast cells were shown clearly. The stainings of VG, PAS and Thionin demonstrated cell types coinciding to histological location. The TB staining did not find red-purple mast cell in tissue sections but one in cell smears. The Grimeliu's argyrophil reaction displayed that intestine wall of tissure sections and stained cells of cell smears were in black clearly. CONCLUSION: HE staining together with histochemical staining can reliably and rapidly distinguish the cell types of Schistosoma japonicum.

Op18/stathmin is involved in the resistance of taxol among different epithelial carcinoma cell lines.

PURPOSE: Taxol is an effective chemotherapeutic agent against epithelial-derived carcinomas, and resistance of carcinoma cells to taxol has developed with the wide prescription of the drug. In this study, five different epithelial carcinoma cell lines were randomly employed to screen the resistant cell line to taxol, and to explore the probable mechanism of taxol-resistant development. MATERIALS AND METHODS: Cells were grouped into the controls and the taxol treated. The treatment effects of five different epithelial carcinoma cell lines, including CNE1, Hep3B-2, MGC, MCF-7, and NCI-H1299, after being treated by taxol were analyzed through inspecting the ratios of cellular apoptosis, inhibition of cellular proliferation, the capability of cell colony formation and wound recovery, and the interference of cell motility and invasion, while western blot analysis and siRNA targeting Op18/stathmin were applied to explore the probable mechanism on the taxol resistance difference in these cells. RESULTS: Nonsmall cell lung cancer NCI-H1299 cells presented obvious taxol resistance, and the inhibition of cell motility and invasion was also the weakest in taxol-treated NCI-H1299 cells among these five cell lines. Microtubule dynamics analysis demonstrated that taxol treatment destroyed normal microtubule arrays and caused obvious microtubule collapse in CNE1, Hep3B-2, MGC, and MCF-7 rather than NCI-H1299, while the latter expressed high levels of microtubule-destabilizing protein Op18/stathmin. Inhibition of Op18/stathmin expression increased the sensitivity to taxol and promoted cellular apoptosis in NCI-H1299 cells. CONCLUSION: NCI-H1299 cells are evidently resistant to taxol-induced cellular apoptosis, inhibition of cellular proliferation and wound recovery, as well as cell migration and invasion interference, which are closely associated with the changes of microtubule dynamics. High expression of Op18/stathmin is perhaps a crucial determinant of taxol-resistant development in NCI-H1299 cells.