Secreted meningeal chemokines, but not VEGFA, modulate the migratory properties of medulloblastoma cells.

Leptomeningeal metastasis is a cause of morbidity and mortality in medulloblastoma, but the understanding of molecular mechanisms driving this process is nascent. In this study, we examined the secretory chemokine profile of medulloblastoma cells (DAOY) and a meningothelial cell line (BMEN1). Conditioned media (CM) of meningothelial cells increased adhesion, spreading and migration of medulloblastoma. VEGFA was identified at elevated levels in the CM from BMEN1 cells (as compared to DAOY CM); however, recombinant VEGFA alone was insufficient to enhance medulloblastoma cell migration. In addition, bevacizumab, the VEGFA scavenging monoclonal antibody, did not block the migratory phenotype induced by the CM. These results reveal that paracrine factors secreted by meningothelial cells can influence migration and adherence of medulloblastoma tumor cells, but VEGFA may not be a specific target for therapeutic intervention in this context.

Surgical resection of breast cancers: Molecular analysis of cancer stem cells in residual disease.

BACKGROUND: Approximately 70% of breast cancer patients have residual disease after neoadjuvant chemotherapy. This study was designed to determine whether breast cancer cells with stemlike properties are present in residual disease after neoadjuvant chemotherapy and whether they exhibit oncogenic mutations. The presence of breast cancer cells with stemlike properties with specific mutations may help explain the poor prognosis associated with residual disease. METHODS: A total of 68 breast cancer specimens were collected at the time of mastectomy or lumpectomy. A total of 44 were chemotherapy naïve and 24 were collected as residual disease after neoadjuvant chemotherapy. Tumor cells were collected by fluorescence-activated cell sorting, with breast cancer cells with stemlike properties specifically identified using breast stem cell associated antibodies. Whole tumor specimens and fluorescence-activated cell sorting breast cancer cells with stemlike properties were analyzed for genetic mutations, including PIK3CA. RESULTS: Breast cancer cells with stemlike properties, demonstrating EpCAM-positive, CD44-positive, CD49f±, CD24± expression were present in chemotherapy-naïve tumors and residual disease. In both chemotherapy-naïve and residual disease specimens the highest frequency of PIK3CA mutations were detected in CD49f-CD24+ BCSCs (39% and 33%, respectively). PIK3CA mutations were detected in all stages of breast cancer (35%), in both chemotherapy naïve (39%) and residual disease (29%) and in both estrogen receptor positive (41%) and negative tumors (14%) (P = ns). Various PIK3CA mutations were identified in chemotherapy-naïve specimens versus residual disease specimens in both patient-paired and unpaired breast cancers. CONCLUSION: Breast cancer cells with stemlike properties with mutations in PIK3CA were present in chemotherapy-naïve breast cancers and residual disease after neoadjuvant chemotherapy. These results demonstrate that neoadjuvant chemotherapy does not completely eradicate PIK3CA-defective breast cancer cells with stemlike properties. Although these findings may help explain the poor clinical outcomes in patients with residual disease, they also identify breast cancer cells with stemlike-property targets for therapies.

IGF1R as a Key Target in High Risk, Metastatic Medulloblastoma.

Risk or presence of metastasis in medulloblastoma causes substantial treatment-related morbidity and overall mortality. Through the comparison of cytokines and growth factors in the cerebrospinal fluid (CSF) of metastatic medulloblastoma patients with factors also in conditioned media of metastatic MYC amplified medulloblastoma or leptomeningeal cells, we were led to explore the bioactivity of IGF1 in medulloblastoma by elevated CSF levels of IGF1, IGF-sequestering IGFBP3, IGFBP3-cleaving proteases (MMP and tPA), and protease modulators (TIMP1 and PAI-1). IGF1 led not only to receptor phosphorylation but also accelerated migration/adhesion in MYC amplified medulloblastoma cells in the context of appropriate matrix or meningothelial cells. Clinical correlation suggests a peri-/sub-meningothelial source of IGF-liberating proteases that could facilitate leptomeningeal metastasis. In parallel, studies of key factors responsible for cell autonomous growth in MYC amplified medulloblastoma prioritized IGF1R inhibitors. Together, our studies identify IGF1R as a high value target for clinical trials in high risk medulloblastoma.

Gene expression signatures of breast cancer stem and progenitor cells do not exhibit features of Warburg metabolism.

INTRODUCTION: Cancers are believed to adapt to continual changes in glucose and oxygen availability by relying almost exclusively on glycolytic metabolism for energy (i.e. the Warburg effect). The process by which breast cancers sustain growth in avascular tissue is thought to be mediated via aberrant hypoxia response with ensuing shifts in glycolytic metabolism. Given their role in initiating and perpetuating tumors, we sought to determine whether breast cancer stem and progenitor cells play an instrumental role in this adaptive metabolic response. METHODS: Breast cancer stem/progenitor cells were isolated from invasive ductal carcinomas, and benign stem cells (SC) were isolated from reduction mammoplasty tissues. Relative expression of 33 genes involved in hypoxia and glucose metabolism was evaluated in flow cytometrically isolated stem and progenitor cell populations. Significance between cohorts and cell populations was determined using Student's 2-tailed t test. RESULTS: While benign stem/progenitor cells exhibited few significant inter-group differences in expression of genes involved in hypoxia regulation or glucose metabolism, breast cancer stem/progenitor cells demonstrated significant inter-group variability. Breast cancer stem/progenitor cells adapted to microenvironments through changes in stem cell numbers and transcription of glycolytic genes. One of four breast cancer stem/progenitor cells subpopulations exhibited an aerobic glycolysis gene expression signature. This subpopulation comprises the majority of the tumor and therefore best reflects invasive ductal carcinoma tumor biology. Although PI3K/AKT mutations are associated with increased proliferation of breast cancer cells, mutations in breast cancer stem/progenitor cells subpopulations did not correlate with changes in metabolic gene expression. CONCLUSIONS: The adaptive capacity of breast cancer stem/progenitor cells may enable tumors to survive variable conditions encountered during progressive stages of cancer growth.