Purpose: The presence of disseminated tumor cells (DTC) in the bone marrow of breast cancer patients is an acknowledged independent prognostic factor.The biological metastatic potential of these cells has not yet been shown. The presence of putative breast cancer stem cells is shown both in primary tumors and distant metastases. These cells with a CD44 + CD24À/low phenotype represent a minor population in primary breast cancer and are associated with self-renewal and tumorigenic potential. Recognizing the potential effect of prevalence of putative stem cells among DTC, we evaluated the bone marrow DTC. Experimental Design: We employed the double/triple-staining immunohistochemistry protocol and modified the established bone marrow cytokeratin (CK) staining protocol by adding steps for additional antigens, CD44 and/or CD24. We evaluated 50 bone marrow specimens, previously categorized as CK + from early breast cancer patients. CK + cells were examined for CD44 and CD24 expression by light microscopy, fluorescence microscopy, and spectral imaging. Results: We detected the putative stem cell^like phenotype in all CK + specimens. The mean prevalence of putative stem/progenitor cells was 72% and median prevalence was 65% (range, 33-100%) among the overall DTC per patient, compared with primary tumors where this phenotype is reported in <10% of cells.Conclusions: This is the first evidence of the existence of the putative stem-like phenotype within the DTC in bone marrow in early breast cancer patients. All patients had a putative stem cell phenotype among the DTC and most individual DTC showed such phenotype. Future molecular characterization of these cells is warranted.

EphB4, a member of the largest family of receptor tyrosine kinases, is normally expressed on endothelial and neuronal cells. Although aberrant expression of EphB4 has been reported in several human tumors, including breast cancer, its functional significance is not understood. We report here that EphB4 is expressed in 7 of 12 (58%) human breast cancer specimens and 4 of 4 (100%) breast tumor cell lines examined. Overexpression of EphB4 in breast cancer cells was driven by gene amplification and by the erbB family of receptors via activation of Janus tyrosine kinase-signal transducers and activators of transcription and protein kinase B. The aberrantly expressed receptor was phosphorylated by its natural ligand, EphrinB2, and signaled via the protein kinase B pathway. Targeted knockdown of EphB4 expression by small interference RNA (and antisense oligodeoxynucleotides (ODNs)) led to dose-dependent reduction in cell survival, increased apoptosis, and sensitization to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Antisense ODN-mediated EphB4 knockdown resulted in reduced tumor growth in a murine tumor xenograft model. Antisense ODNtreated tumors were 72% smaller than control tumors at 6 weeks, with an 86% reduction in proliferating cells, 15-fold increase in apoptosis, and 44% reduction in tumor microvasculature. Our data indicate that biologically active EphB4 functions as a survival factor in breast cancer and is a novel target for therapy. (Am J

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Posterior fossa ependymomas (EPN_PF) in children comprise two morphologically identical, but biologically distinct tumor entities. Group-A (EPN_PFA) tumors have a poor prognosis and require intensive therapy. In contrast, group-B tumors (EPN_PFB) exhibit excellent prognosis and the current consensus opinion recommends future clinical trials to test the possibility of treatment de-escalation in these patients. Therefore distinguishing these two tumor subtypes is critical. EPN_PFA and EPN_PFB can be distinguished based on DNA methylation signatures, but these assays are not routinely available. We have previously shown that a subset of poorly prognostic childhood EPN_PF exhibits global reduction in H3K27me3. Therefore, we set out to determine whether a simple immunohistochemical assay for H3K27me3 could be used to segregate EPN_PFA from EPN_PFB tumors. We assembled a cohort of 230 childhood ependymomas and H3K27me3 immunohistochemistry was assessed as positive or negative in a blinded manner. H3K27me3 staining results were compared with DNA methylation-based subgroup information available in 112 samples [EPN_PFA (n=72) and EPN_PFB tumors (n=40)]. H3K27me3 staining was globally reduced in EPN_PFA tumors and immunohistochemistry showed 99% sensitivity and 100% specificity in segregating EPN_PFA from EPN_PFB tumors. Moreover, H3K27me3 immunostaining was sufficient to delineate patients with worse prognosis in two independent, non-overlapping cohorts (n=133 and n=97). In conclusion, immunohistochemical evaluation of H3K27me3 global reduction is an economic, easily available and readily adaptable method for defining high-risk EPN_PFA from low-risk posterior fossa EPN_PFB tumors to inform prognosis and to enable the design of future clinical trials.

The receptor tyrosine kinase EphB2 is expressed by colon progenitor cells; however, only 39% of colorectal tumors express EphB2 and expression levels decline with disease progression. Conversely, EphB4 is absent in normal colon but is expressed in all 102 colorectal cancer specimens analyzed, and its expression level correlates with higher tumor stage and grade. Both EphB4 and EphB2 are regulated by the Wnt pathway, the activation of which is critically required for the progression of colorectal cancer. Differential usage of transcriptional coactivator cyclic AMP-responsive element binding protein-binding protein (CBP) over p300 by the Wnt/Bcatenin pathway is known to suppress differentiation and increase proliferation. We show that the B-catenin-CBP complex induces EphB4 and represses EphB2, in contrast to the B-catenin-p300 complex. Gain of EphB4 provides survival advantage to tumor cells and resistance to innate tumor necrosis factor-related apoptosis-inducing ligand-mediated cell death. Knockdown of EphB4 inhibits tumor growth and metastases. Our work is the first to show that EphB4 is preferentially induced in colorectal cancer, in contrast to EphB2, whereby tumor cells acquire a survival advantage.

Context Immunochemical staining of sentinel lymph nodes (SLNs) and bone marrow identifies breast cancer metastases not seen with routine pathologic or clinical examination. Objective To determine the association between survival and metastases detected by immunochemical staining of SLNs and bone marrow from patients with early-stage breast cancer. Design, Setting, and Patients From May 1999 to May 2003, 126 sites in the American College of Surgeons Oncology Group Z0010 trial enrolled women with clinical T1–T2, N0, M0 invasive breast carcinoma in a prospective observational study. Interventions All patients underwent breast-conserving surgery and SLN dissection; bone marrow aspiration at the time of operation was initially optional and subsequently mandatory (March 2001). SLN specimens (hematoxylin-eosin negative) and bone marrow specimens were sent to a central laboratory for immunochemical staining; treating clinicians were blinded to results. Main Outcome Measures Overall survival (primary end point) and disease-free survival (a secondary end point). Results Of 5119 (98.3%) SLN specimens, 3904 (76.3%) were tumor-negative by hematoxylin-eosin staining. Of 3326 SLN specimens examined by immunohistochemistry, 349 (10.5%) were tumor-positive. Of 3413 bone marrow specimens examined by immunocytochemistry, 104 (3.0%) were positive. At a median follow-up of 6.3 years (through April 2010), 435 patients had died and 376 had disease recurrence. Immunohistochemical evidence of SLN metastases was not significantly associated with overall survival (5-year rates: 95.7% (95% CI, 95.0%–96.5%) for immunohistochemical positive and 95.1% (95% CI, 92.7%–97.5% for immunohistochemical negative disease, P=0.64), unadjusted hazard ratio [HR], 0.90; 95% confidence interval [CI], 0.59–1.39; P=.64). Bone marrow metastases were associated with decreased overall survival (5-year rates: 95.0% (95% CI, 94.3%–95.8%) and 90.1% (95% CI, 84.5%–96.1%), respectively (P=.01) (unadjusted HR, 1.94; 95% CI, 1.02–3.67; P=.04), but neither immunohistochemical evidence of tumor in SLNs (adjusted HR, 0.88; 95% CI, 0.45–1.71; P=.70) nor immunocytochemical evidence of tumor in bone marrow (adjusted HR, 1.83; 95% CI, 0.79–4.26; P=.15) was statistically significant on multivariable analysis. Conclusion Among women receiving breast-conserving therapy and SLN dissection, immunochemical evidence of SLN metastasis was not associated with decreased overall survival over a median of 6.3 years whereas, occult bone marrow metastasis, although rare, was associated with decreased survival. Trial Registration ClinicalTrials.gov number, NCT00003854

Background: Induction of molecular chaperone Grp78 (78-kDa glucose-regulated protein) occurs in stress conditions that often characterize tumor microenvironments.We investigated the role of Grp78 in prostate cancer progression and the development of castration resistance, where cancer cells continue to survive despite the stress of an androgen-starved environment. Experimental Design: Immunohistochemistry was done to examine Grp78 expression in 219 prostate cancers from patients with pathologic stage T 3 N 0 M 0 disease [androgen ablation naive (untreated) and androgen ablation exposed (treated)] and castration-resistant prostate cancer. Classification of tumors was based on intensity of Grp78 cytoplasmic immunoreactivity and percentage of immunoreactive tumor cells. The associations of Grp78 expression with prostate cancer recurrence (clinical and/or serum prostate-specific antigen) and survival were examined in the untreated stage T 3 N 0 M 0 group. Grp78 expression was also analyzed in the androgendependent LNCaP and castration-resistant C42B cell lines. Results: The percentage of tumor cells expressing Grp78 was strongly associated with castration-resistant status (P = 0.005). Increased Grp78 expression was consistently associated with greater risk of prostate cancer recurrence and worse overall survival in patients who had not undergone prior hormonal manipulation. Grp78 expression was also increased in the castrationresistant LNCaP-derived cell line C42B and in LNCaP cells grown in androgen-deprived conditions compared with LNCaP cells grown in androgen-rich media. Conclusion: Our findings show that up-regulation of Grp78 is associated with the development of castration resistance, possibly in part by augmenting cell survival as previously suggested, and may serve as an important prognostic indicator of recurrence in a subset of patients withT 3 N 0 M 0 disease.

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