Byunghoo Song

BIS-mediated STAT3 stabilization regulates glioblastoma stem cell-like phenotypes

Glioblastoma stem cells (GSCs) are a subpopulation of highly tumorigenic and stem-like cells that are responsible for resistance to conventional therapy. Bcl-2-intreacting cell death suppressor (BIS; also known as BAG3) is an anti-apoptotic protein that is highly expressed in human cancers with various origins, including glioblastoma. In the present study, to investigate the role of BIS in GSC subpopulation, we examined the expression profile of BIS in A172 and U87-MG glioblastoma cell lines under specific in vitro culture conditions that enrich GSC-like cells in spheres. Both BIS mRNA and protein levels significantly increased under the sphere-forming condition as compared with standard culture conditions. BIS depletion resulted in notable decreases in sphere-forming activity and was accompanied with decreases in SOX-2 expression. The expression of STAT3, a master regulator of stemness, also decreased following BIS depletion concomitant with decreases in the nuclear levels of active phosphorylated STAT3, while ectopic STAT3 overexpression resulted in recovery of sphere-forming activity in BIS-knockdown glioblastoma cells. Additionally, immunoprecipitation and confocal microscopy revealed that BIS physically interacts with STAT3. Furthermore, BIS depletion increased STAT3 ubiquitination, suggesting that BIS is necessary for STAT3 stabilization in GSC-like cells. BIS depletion also affected epithelial-to-mesenchymal transition-related genes as evidenced by decrease in SNAIL and MMP-2 expression and increase in E-cadherin expression in GSC-like cells. Our findings suggest that high levels of BIS expression might confer stem-cell-like properties on cancer cells through STAT3 stabilization, indicating that BIS is a potential target in cancer therapy.

Mesenchymal Stromal Cells Promote Tumor Progression in Fibrosarcoma and Gastric Cancer Cells

Background Extensive evidence has accumulated regarding the role of mesenchymal stromal cells (MSCs) in tumor progression, but the exact effects and mechanisms underlying this role remain unclear. We investigated the effects of MSC-associated tumor progression in MSC-sarcoma models and a gastric cancer metastatic model. Methods We conducted an in vitro growth kinetics assay and an in vivo tumor progression assay for sarcoma cells and gastric cancer cells in the presence or absence of MSCs. Results MSC-cocultured human fibrosarcoma cells (HT1080) showed accelerated growth compared with HT1080 alone (79- vs 37-fold change, p<.050). For HT1080, human MSC-coinjected tumors showed significantly greater and highly infiltrative growth compared to those of HT1080 alone (p=.035). For mouse fibrosarcoma cells (WEHI164), mouse MSC-coinjected tumors had greater volume than those of WEHI164 alone (p=.141). For rat sarcoma cells (RR1022), rat MSC-coinjected tumors exhibited greater volume and infiltrative growth than those of RR1022 alone (p=.050). For human gastric cancer cells (5FU), tumors of 5FU alone were compact, nodular in shape, and expansile with good demarcation and no definite lung metastatic nodules, whereas tumors grown in the presence of human MSCs showed highly desmoplastic and infiltrative growth and multiple lung metastasis. Conclusions We observed morphological evidence for MSC-associated tumor progression of fibrosarcomas and gastric cancer cells.

Abstract P4-03-01: Distance of breast cancer from the skin influence axillary nodal metastasis

Background: In breast cancer, axillary lymph node status is one of the most important prognostic variables and a crucial component to the staging system. Moreover, cancers underlying skin are willing to access to the lymphatics and cause lymphatic dissemination. Therefore, there seems an association between proximity of breast cancer to the skin and the incidence of axillary node positivity or local recurrence. The aim of this study was to determine whether distance of breast cancers from the skin affects the the clinical and pathologic features including the likelihood of axillary nodal metastases, ipsilateral breast cancer recurrence, and recurrence free survival. Methods: Between January 2003 and December 2009, data were collected prospectively regarding 1005 consecutive breast cancer patients who underwent surgical treatment. The exclusion criteria were non-invasive carcinoma (e.g. Ductal Carcinoma In Situ), prior breast surgery, previous radiotherapy or neo-adjuvant chemotherapy and previous endocrine therapy. The distance of the tumor from the skin surface was measured from the skin to the most anterior hypoechoic leading edge of the lesion. Results: A total of 891 patients were included in the statistical analysis, 603(68%) had no axillary nodal metastasis, 288(32%) had axillary nodal metastasis. Distance of breast cancer from the skin less than 3mm induced more axillary nodal metastasis ( P = 0.039). However, there was no statistical significant correlation between distance of breast cancer from the skin less than 3mm and ipsilateral breast tumor recurrence ( P = 0.788) or recurrence-free survival ( P = 0.353). Conclusion: Breast cancers located closer to the skin have a higher incidence of axillary nodal metastasis. When evaluating a breast cancer patient and considering the risk of nodal metastasis the distance of the tumor from the skin should be considered. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-03-01.

P3-07-07: Effect of Sentinel Lymph Node Biopsy without Axillary Lymph Node Dissection on Overall Survival in Patients with T1 or T2 Node-Positive Breast Cancer: A Report from the Korean Breast Cancer Society.

Introduction: Sentinel lymph node biopsy (SLNB) is accepted as an alternative method to axillary lymph node dissection for staging axillary lymph node status in clinically node-negative breast cancer. Current practical guidelines recommend that axillary lymph node dissection (ALND) should be performed in cases with sentinel node metastasis, and most of node-positive patients should receive adjuvant systemic therapy to reduce locoregional/distant recurrence and to improve overall survival irrespective of the number of lymph node metastasis. However, patients with ALND are more likely to develop lymphedema than those with SLNB alone, and appropriate systemic chemotherapy or hormone therapy significantly reduce locoregional and distant recurrence in early breast cancer patients. For this reason, the previous prospective study, American College of Surgeon Oncology Group Z0011 trial, was conducted and it suggested that there is no difference in overall survival between node-positive patients who received breast conserving treatment with SLNB alone and those with ALND after SLNB. This study is aimed to evaluate the difference of survival between node-positive patients who underwent SLNB alone and those who received ALND after SLNB using the Korean Breast Cancer Society registry. Methods: In 87671 patients with breast cancer in the registry, we enrolled 2581 patients who meet the eligible criteria in the study. All enrolled patients had T1 or T2 breast cancer, and received mastectomy or breast conserving treatment followed by documented adjuvant systemic therapy between Jan. 2001 and Apr. 2011. Log-rank test and Cox-proportional hazard model were used to access the difference of overall survival according to the axillary procedure. Results: There were 197 patients with SLNB alone and 2384 patients with ALND after SLNB, respectively. Smaller tumor size, lower number of nodal metastasis, and higher proportion of breast conserving surgery were shown in patients with SLNB alone than in those with ALND after SLNB. There was no significant difference in overall survival between 2 groups in the log-rank test. ALND after SLNB showed no significant improvement on overall survival in Cox-propotional hazard model adjusted by tumor size, number of nodal metastasis, and operation type (P =0.78, HR=0.73, 95% CI=0.08−6.62). Conclusion: The current study suggests that ALND after SLNB in cases with sentinel lymph node metastasis may not influence on the improvement of overall survival and supports the results of Z0011 trial. Further validation studies are necessary to expand the understanding of the role of performing SLNB alone in patients with node-positive breast cancer. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-07-07.

Abstract P5-03-08: Overexpression of AIB1 mRNA in Breast Cancer Inversely Correlates with Estrogen Receptor Positivity

Background: The AIB1 is a steroid receptor coactivator that promotes the transcriptional activity of nuclear receptors such as estrogen receptor. It is overexpressed at the mRNA level in up to 60% of primary breast carcinomas. Methods: In situ hybridization to examine AIB1 mRNA expression was performed in 113 breast carcinomas in the Catholic university of Korea, from Jan. 2004 to Dec. 2008. We investigated the prognostic significance of AIB1 and the correlation of immunohistochemical staining results of estrogen receptor(ER), progesterone receptor (PR), and Her2/neu. Results: AIB1 mRNA overexpression showed in 55 of 113 (48.7%) breast carcinomas. AIB1 mRNA expression was significantly associated with T stage (P=0.002), but not associated with age, lymph node metastasis, histologic type and histologic grade. High expression of AIB1 mRNA was inversely correlated with expression of ER (P=0.011, R=-0.241) and not significantly associated, but also adversely related, with expression of PR (P=0.101, R=-0.157). AIB1 mRNA overexpression was associated with positivity of Her2/neu (P=0.001, R= 0.311). Survival and recurrent free analysis did not reveal significant association with AIB1 expression. Conclusion: AIB1 mRNA overexpression could be involved in breast cancer by mechanism not totally dependent on steroid receptor cofactor, and may involved other estrogen independent growth pathway such as Her2/neu expression. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P5-03-08.