Sox2 (sex-determining region Y-Box) is one of the master transcriptional factors that are important in maintaining the pluripotency of embryonic stem cells (ESCs). In line with this function, Sox2 expression is largely restricted to ESCs and somatic stem cells. We report that Sox2 is expressed in cell lines and tumor samples derived from ALK-positive anaplastic large cell lymphoma (ALK+ALCL), for which the normal cellular counterpart is believed to be mature T-cells. The expression of Sox2 in ALK+ALCL can be attributed to nucleophosmin-anaplastic lymphoma kinase (NPM-ALK), the oncogenic fusion protein carrying a central pathogenetic role in these tumors. By confocal microscopy, Sox2 protein was detectable in virtually all cells in ALK+ALCL cell lines. However, the transcriptional activity of Sox2, as assessed using a Sox2-responsive reporter construct, was detectable only in a small proportion of cells. Importantly, downregulation of Sox2 using short interfering RNA in isolated Sox2active cells, but not Sox2inactive cells, resulted in a significant decrease in cell growth, invasiveness and tumorigenicity. To conclude, ALK+ALCL represents the first example of a hematologic malignancy that aberrantly expresses Sox2, which represents a novel mechanism by which NPM-ALK mediates tumorigenesis. We also found that the transcriptional activity and oncogenic effects of Sox2 can be heterogeneous in cancer cells.

A genetic screen using a library of 6,961 siRNAs led to the identification of SHP-1 (PTPN6), a tumor suppressor frequently mutated in malignant lymphomas, leukemias, and prostate cancer, as a potential synthetic lethal partner of the DNA repair protein polynucleotide kinase/phosphatase (PNKP). After confirming the partnership with SHP-1, we observed that codepletion of PNKP and SHP-1 induced apoptosis. A T-cell lymphoma cell line that is SHP-1 deficient (Karpas 299) was shown to be sensitive to a chemical inhibitor of PNKP, but resistance was restored by expression of wild-type SHP-1 in these cells. We determined that while SHP-1 depletion does not significantly impact DNA strand-break repair, it does amplify the level of reactive oxygen species (ROS) and elevate endogenous DNA damage. The ROS scavenger WR1065 afforded protection to SHP-1-depleted cells treated with the PNKP inhibitor. We propose that codisruption of SHP-1 and PNKP leads to an increase in DNA damage that escapes repair, resulting in the accumulation of cytotoxic double-strand breaks and induction of apoptosis. This supports an alternative paradigm for synthetic lethal partnerships that could be exploited therapeutically. Cancer Res; 72(22); 5934-44. Ó2012 AACR.

Cysteine- rich secretory protein 3 (CRISP3) prognostic significance in prostate cancer (PCA) has generated mixed result. Herein, we investigated and independently validated CRISP3 expression in relation to ERG and PTEN genomic aberrations and clinical outcome. CRISP3 protein expression was examined by immunohistochemistry using a cohort of patients with localized PCA (n = 215) and castration resistant PCA (CRPC) (n = 46). The Memorial Sloan Kettering (MSKCC) and Swedish cohorts were used for prognostic validation. Results showed, CRISP3 protein intensity to be significantly associated with neoplastic epithelium, being highest in CRPC vs. benign prostate tissue (p < 0.0001), but was not related to Gleason score (GS). CRISP3 mRNA was significantly associated with higher GS (p = 0.022 in MSKCC, p = 1.1e-4 in Swedish). Significant association between CRISP3 expression and clinical outcome was documented at the mRNA but not the protein expression levels. CRISP3 mRNA expression was related to biochemical recurrence in the MSKCC (p = 0.038) and lethal disease in the Swedish cohort (p = 0.0086) and retained its prognostic value in the subgroup of patients with GS 6 & 7. Furthermore, CRISP3 protein and mRNA expression was significantly associated with positive ERG status and with PTEN deletions. Functional biology analysis documented phenylalanine metabolism as the most significant pathway governing high CRISP3 and ERG expression in this subtype of PCA. In conclusion, the combined status of CRISP3, ERG and PTEN define a molecular subtype of PCA with poorest and lethal outcome. Assessing their combined value may be of added value in stratifying patients into different prognostic groups and identify those with poorest clinical outcome.

The fusion tyrosine kinase NPM-ALK is central to the pathogenesis of ALK-positive anaplastic large cell lymphoma (ALK ؉ ALCL). We recently identified that MSH2, a key DNA mismatch repair (MMR) protein integral to the suppression of tumorigenesis, is an NPM-ALK-interacting protein. In this study, we found in vitro evidence that enforced expression of NPM-ALK in HEK293 cells suppressed MMR function. Correlating with these findings, six of nine ALK ؉ ALCL tumors displayed evidence of microsatellite instability, as opposed to none of the eight normal DNA control samples (P ‫؍‬ 0.007, Student's t-test). Using co-immunoprecipitation, we found that increasing levels of NPM-ALK expression in HEK293 cells resulted in decreased levels of MSH6 bound to MSH2, whereas MSH2·NPM-ALK binding was increased. The NPM-ALK·MSH2 interaction was dependent on the activation/autophosphorylation of NPM-ALK, and the Y191 residue of NPM-ALK was a crucial site for this interaction and NPM-ALK-mediated MMR suppression. MSH2 was found to be tyrosine phosphorylated in the presence of NPM-ALK. Finally, NPM-ALK impeded the expected DNA damage-induced translocation of MSH2 out of the cytoplasm. To conclude, our data support a model in which the suppression of MMR by NPM-ALK is attributed to its ability to interfere with normal MSH2 biochemistry and function.

Interleukin (IL)-

This study confirms a significant prognostic role for assessing ERG and PTEN in men with prostate cancer. It supports a role for utilizing combined ERG/PTEN status clinically and prospectively for stratifying PCa patients into different prognostic groups.

Silencing ANK3 results in significant reduction of cell proliferation through an AR-independent mechanism. ANK3 knockdown results in significant increase in cell invasion through an AR-dependent mechanism. ANK3 is a regulator of AR protein stability. ANK3 knockdown also promotes cancer cell invasion and extravasation in vivo using the avian embryo model.

The inhibitor of growth family member 3 (ING3) is a member of the ING tumor suppressor family. Although its expression has been reported in various types of cancers, the role of ING3 and its prognostic value in prostate cancer (PCa) has not been investigated. ING3 expression and prognostic value was assessed in a cohort of PCa patients (n = 312) treated with transurethral resection of prostate using immumoflourescent automated quantitative analysis (AQUA) system. In vitro studies were carried out in conjunction to investigate its expression in various PCa cell lines. ING3 knockdown was also carried out in DU145 cell lines to assess for any changes in invasion and migration. ING3 expression was highest in benign prostate tissues (mean 3.2 ± 0.54) compared to PCa (mean 2.5 ± 0.26) (p = 0.437), advanced prostate cancer (AdvPCa) (mean 1.5 ± 0.32) (p = 0.004), and castration-resistant prostate cancer (CRPC) (mean 2.28 ± 0.32) (p = 0.285). ING3 expression was inversely correlated to Gleason score (p = 0.039) and ETS-related gene (ERG) expression (p = 0.019). Higher ING3 expression was marginally associated with lethal disease (p = 0.052), and this was more pronounced in patients with ERG-negative status (p = 0.018). Inhibition of ING3 in DU145 PCa cells using small interfering RNA (siRNA) was associated with decreased cell invasion (p = 0.0016) and cell migration compared to control cells. ING3 is significantly associated with PCa disease progression and cancer-specific mortality. To our knowledge, this is the first report suggesting an oncogenic function of ING3, previously well known as a tumor suppressor protein. Further studies should investigate potential-related pathways in association to ING3.