PIM-1 gene RNA interference induces growth inhibition and apoptosis of prostate cancer cells and suppresses tumor progression in vivo

Plantaricin BM-1 decreases viability of SW480 human colorectal cancer cells by inducing caspase-dependent apoptosis

Plantaricin BM-1 is a class IIa bacteriocin produced by Lactobacillus plantarum BM-1 that has significant antimicrobial activity against food-borne bacteria. In this study, a cell proliferation assay and scanning electron microscopy were used to detect changes in the viability of SW480, Caco-2, and HCT-116 colorectal cancer cells treated with plantaricin BM-1. We found that plantaricin BM-1 significantly reduced the viability of all colorectal cancer cell lines tested, especially that of the SW480 cells. Scanning electron microscopy showed that plantaricin BM-1 treatment reduced the number of microvilli and slightly collapsed the morphology of SW480 cells. Fluorescence microscopy and flow cytometry demonstrated that plantaricin BM-1 induced apoptosis of SW480 cells in a concentration-dependent manner. Western blotting further showed that plantaricin BM-1-induced apoptosis of SW480 cells was mediated by the caspase pathway. Finally, transcriptomic analysis showed that 69 genes were differentially expressed after plantaricin BM-1 treatment (p < 0.05), of which 65 were downregulated and four were upregulated. The Kyoto Encyclopedia of Genes and Genomes enrichment analysis showed that expression levels of genes involved in the TNF, NF-κB, and MAPK signaling pathways, as well as functional categories such as microRNAs in cancer and transcriptional misregulation in cancer, were affected in SW480 cells following the treatment with plantaricin BM-1. In conclusion, plantaricin BM-1 induced death in SW480 cells via the caspase-dependent apoptosis pathway. Our study provides important information for further development of plantaricin BM-1 for potential applications in anti-colorectal cancer.

Synthesis and Biological Evaluation of Pyrazolo[1,5-a]pyrimidine Compounds as Potent and Selective Pim-1 Inhibitors

Pim-1 has emerged as an attractive target for developing therapeutic agents for treating disorders involving abnormal cell growth, especially cancers. Herein we present lead optimization, chemical synthesis and biological evaluation of pyrazolo[1,5-a]pyrimidine compounds as potent and selective inhibitors of Pim-1 starting from a hit from virtual screening. These pyrazolo[1,5-a]pyrimidine compounds strongly inhibited Pim-1 and Flt-3 kinases. Selected compounds suppressed both the phosphorylation of BAD protein in a cell-based assay and 2-dimensional colony formation in a clonogenic cell survival assay at submicromolar potency, suggesting that cellular activity was mediated through inhibition of Pim-1. Moreover, these Pim-1 inhibitors did not show significant hERG inhibition at 30 μM concentration. The lead compound proved to be highly selective against a panel of 119 oncogenic kinases, indicating it had an improved safety profile compared with the first generation Pim-1 inhibitor SGI-1776.

Functional role and therapeutic potential of the pim-1 kinase in colon carcinoma

PURPOSE

The provirus integration site for Moloney murine leukemia virus 1 (Pim-1) kinase is overexpressed in various tumors and has been linked to poor prognosis. Its role as proto-oncogene is based on several Pim-1 target proteins involved in pivotal cellular processes. Here, we explore the functional relevance of Pim-1 in colon carcinoma.

EXPERIMENTAL DESIGN

RNAi-based knockdown approaches, as well as a specific small molecule inhibitor, were used to inhibit Pim-1 in colon carcinoma cells. The effects were analyzed regarding proliferation, apoptosis, sensitization toward cytostatic treatment, and overall antitumor effect in vitro and in mouse tumor models in vivo.

RESULTS

We demonstrate antiproliferative, proapoptotic, and overall antitumor effects of Pim-1 inhibition. The sensitization to 5-fluorouracil (5-FU) treatment upon Pim-1 knockdown offers new possibilities for combinatorial treatment approaches. Importantly, this also antagonizes a 5-FU-triggered Pim-1 up-regulation, which is mediated by decreased levels of miR-15b, a microRNA we newly identify to regulate Pim-1. The analysis of the molecular effects of Pim-1 inhibition reveals a complex regulatory network, with therapeutic Pim-1 repression leading to major changes in oncogenic signal transduction with regard to p21(Cip1/WAF1), STAT3, c-jun-N-terminal kinase (JNK), c-Myc, and survivin and in the levels of apoptosis-related proteins Puma, Bax, and Bcl-xL.

CONCLUSIONS

We demonstrate that Pim-1 plays a pivotal role in several tumor-relevant signaling pathways and establish the functional relevance of Pim-1 in colon carcinoma. Our results also substantiate the RNAi-mediated Pim-1 knockdown based on polymeric polyethylenimine/small interfering RNA nanoparticles as a promising therapeutic approach.

U1 snRNP-Dependent Suppression of Polyadenylation: Physiological Role and Therapeutic Opportunities in Cancer

Pre-mRNA splicing and polyadenylation are critical steps in the maturation of eukaryotic mRNA. U1 snRNP is an essential component of the splicing machinery and participates in splice-site selection and spliceosome assembly by base-pairing to the 5' splice site. U1 snRNP also plays an additional, nonsplicing global function in 3' end mRNA processing; it actively suppresses the polyadenylation machinery from using early, mostly intronic polyadenylation signals which would lead to aberrant, truncated mRNAs. Thus, U1 snRNP safeguards pre-mRNA transcripts against premature polyadenylation and contributes to the regulation of alternative polyadenylation. Here, we review the role of U1 snRNP in 3' end mRNA processing, outline the evidence that led to the recognition of its physiological, general role in inhibiting polyadenylation, and finally highlight the possibility of manipulating this U1 snRNP function for therapeutic purposes in cancer.

U1 adaptors for the therapeutic knockdown of the oncogene pim-1 kinase in glioblastoma

U1 small nuclear interference (U1i) has recently been described as a novel gene silencing mechanism. U1i employs short oligonucleotides, so-called U1 adaptors, for specific gene knockdown, expanding the field of current silencing strategies that are primarily based on RNA interference (RNAi) or antisense. Despite the potential of U1 adaptors as therapeutic agents, their in vivo application has not yet been studied. Here we explore U1i by analyzing U1 adaptor-mediated silencing of the oncogene Pim-1 in glioblastoma cells. We have generated Pim-1-specific U1 adaptors comprising DNA, locked nucleic acids (LNA), and 2'-O-Methyl RNA and demonstrate their ability to induce a Pim-1 knockdown, leading to antiproliferative and pro-apoptotic effects. For the therapeutic in vivo application of U1 adaptors, we establish their complexation with branched low molecular weight polyethylenimine (PEI). Upon injection of nanoscale PEI/adaptor complexes into subcutaneous glioblastoma xenografts in mice, we observed the knockdown of Pim-1 that resulted in the suppression of tumor growth. The absence of hepatotoxicity and immune stimulation also demonstrates the biocompatibility of PEI/adaptor complexes. We conclude that U1i represents an alternative to RNAi for the therapeutic silencing of pathologically upregulated genes and demonstrate the functional relevance of Pim-1 oncogene knockdown in glioblastoma. We furthermore introduce nanoscale PEI/adaptor complexes as efficient and safe for in vivo application, thus offering novel therapeutic approaches based on U1i-mediated gene knockdown.

Conditional transgenic expression of PIM1 kinase in prostate induces inflammation-dependent neoplasia

The Pim proteins are a family of highly homologous protein serine/threonine kinases that have been found to be overexpressed in cancer. Elevated levels of Pim1 kinase were first discovered in human leukemia and lymphomas. However, more recently Pim1 was found to be increased in solid tumors, including pancreatic and prostate cancers, and has been proposed as a prognostic marker. Although the Pim kinases have been identified as oncogenes in transgenic models, they have weak transforming abilities on their own. However, they have been shown to greatly enhance the ability of other genes or chemical carcinogens to induce tumors. To explore the role of Pim1 in prostate cancer, we generated conditional Pim1 transgenic mice, expressed Pim1 in prostate epithelium, and analyzed the contribution of PIM1 to neoplastic initiation and progression. Accordingly, we explored the effect of PIM1 overexpression in 3 different settings: upon hormone treatment, during aging, and in combination with the absence of one Pten allele. We have found that Pim1 overexpression increased the severity of mouse prostate intraepithelial neoplasias (mPIN) moderately in all three settings. Furthermore, Pim1 overexpression, in combination with the hormone treatment, increased inflammation surrounding target tissues leading to pyelonephritis in transgenic animals. Analysis of senescence induced in these prostatic lesions showed that the lesions induced in the presence of inflammation exhibited different behavior than those induced in the absence of inflammation. While high grade prostate preneoplastic lesions, mPIN grades III and IV, in the presence of inflammation did not show any senescence markers and demonstrated high levels of Ki67 staining, untreated animals without inflammation showed senescence markers and had low levels of Ki67 staining in similar high grade lesions. Our data suggest that Pim1 might contribute to progression rather than initiation in prostate neoplasia.

Inhibition of Pim-1 attenuates the proliferation and migration in nasopharyngeal carcinoma cells

OBJECTIVE

To explore the role of proto-oncogene Pim-1 in the proliferation and migration of nasopharyngeal carcinoma (NPC) cells.

METHODS

Pim-1 expressions in NPC cell lines CNE1, CNE1-GL, CNE-2Z and C666-1 were examined by RT-PCR, western blotting and immunoflucesence, respectively. After CNE1, CNE1-GL and C666-1 cells were treated with different concentrations of Pim-1 special inhibitor, quercetagetin, the cell viability, colony formation rate and migration ability were analyzed.

RESULTS

Pim-1 expression was negative in well-differentiated CNE1 cells, whereas expressed weakly positive in poor-differentiated CNE-2Z cells and strongly positive in undifferentiated C666-1 cells. Interestingly, CNE1-GL cells that derived from CNE1 transfected with an Epstein Barr virus latent membrane protein-1 over-expression plasmid displayed stronger expression of Pim-1. Treatment of CNE1-GL and C666-1 cells with quercetagetin significantly decreased the cell viability, colony formation rate and migration ability but not the CNE1 cells.

CONCLUSIONS

These findings suggest that Pim-1 overexpression contributes to NPC proliferation and migration, and targeting Pim-1 may be a potential treatment for anti-Pim-1-expressed NPCs.

Overexpression of Pim-1 in bladder cancer

Background

Pim-1 is a serine-threonine kinase which promotes early transformation, cell proliferation and cell survival during tumorigenesis. Several studies have demonstrated that Pim-1 kinase play a role in different cancer types, however, the function of Pim-1 in bladder cancer is poorly understood.

Methods

Expression and localization of Pim-1 in human normal and malignant bladder specimens were examined by Immunohistochemistry and Pim-1 staining score was compared with several clinicopathologic parameters. To further demonstrate the biological function of Pim-1 in bladder cancer, its expression was validated in five bladder cancer cell lines by western blot and immunohistochemistry analyses. Subsequent knockdown of Pim-1 was achieved by lentivirus encoding small interfering RNA, and the effect of Pim-1 on bladder cell survival and drug sensitivity were further assessed by colony formation and cell proliferation assays.

Results

When compared with normal epithelium, Pim-1 was overexpressed in bladder cancer epithelium, and the expression level was higher in invasive bladder cancer than Non-invasive bladder cancer specimens. Pim-1 was also detected in all the bladder cancer cell lines examined in our study. Moreover, the knockdown of Pim-1 significantly inhibited bladder cancer cell growth and also sensitized cells to chemotherapeutic drugs in vitro.

Conclusions

Our results in this study suggest that Pim-1 may play a role in bladder cancer initiation and progression. Since Pim-1 is also involved in bladder cancer cell survival and drug resistance, Pim-1 is a potential candidate for targeted therapy in bladder cancer.