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PDF file - 292K, Supplementary Figure 1: Structure of DPM and H&E-stained end stage tumor sections. Supplementary Figure 2: No gross changes in cellular proliferation, apoptosis or microvessel density are observed in end stage tumors in response to DPM therapy. Supplementary Figure 3: DPM treatment does not maintain expression of ER in late stage carcinomas. Supplementary Figure 4: DPM treatment does not reduce the expression of the PyMT transgene in tumors.

PDF file - 119K, Table 1A. Genes enriched as over-expressed in DPM treatment group Table 1B. Genes enriched as under-expressed in DPM treatment group Table 2A. Functional enrichment (based on GO Biological Process) of genes over-expressed in DPM treatment group using DAVID. Table 2B. Functional enrichment (based on GO Biological Process) of genes under-expressed in DPM treatment group using DAVID. Table 3. Cell growth, proliferation and migration related functions of those genes differentially-enriched in the DPM treatment group Table 4. Comparison of gene expression fold changes between microarray and qPCR. Table 5. Differentially expressed miRNAs in DPM treatment group

PDF file - 164K, Preclinical chemoprevention experimental design

Supplemental Figure 1: OGT expression in oncogene expressing MCF-10A cells. Supplemental Figure 2: Inhibition of PI3K and mTOR does not reduce OGT RNA levels in breast cancer cells. Supplemental Figure 3: OGA expression in breast cancer cells treated with inhibitors. Supplemental Figure 4: MEK/ERK pathway is not sufficient to regulate OGT and O-GlcNAcylation levels. Supplemental Figure 5: OGA expression is reduced in TSC2 -/- MEFs. Supplemental Figure 6: Myc does not regulate OGT RNA levels in cancer cells. Supplemental Figure 7: Proteasomal degradation regulates unfolded OGT. Supplemental Figure 8: MYC regulates OGT protein via transcriptional target HSP90. Supplemental Figure 9: MYC-driven breast cancers overexpress OGT.

Simple Summary Targeting dysregulated cellular metabolism is a promising avenue to treat metastatic disease. The aim of our study was to identify genes downstream of the hypoxia-inducible factor (HIF)-1 transcription factor that are amenable to therapeutic intervention to treat metastatic breast cancer (MBC). We identified creatine kinase, brain isoform (CKB) as an HIF-dependent gene that strongly promotes invasion and metastasis in estrogen-receptor (ER)-negative breast cancer models. Deletion of Ckb also repressed glycolysis and mitochondrial respiration, leading to a reduction in intracellular ATP. Either the deletion of Ckb or inhibition of creatine kinase (CK) activity using the creatine analog cyclocreatine (cCr) repressed cell invasion, the formation of invadopodia and lung metastasis. In addition, when paired with paclitaxel or doxorubicin, cCr enhanced growth inhibition in an additive or synergistic manner. cCr may be an effective anti-metastatic agent in ER-negative, HIF-1α-positive breast cancers, targeting both cellular metabolism and motility, particularly when paired with conventional cytotoxic agents. Abstract The oxygen-responsive hypoxia inducible factor (HIF)-1 promotes several steps of the metastatic cascade. A hypoxic gene signature is enriched in triple-negative breast cancers (TNBCs) and is correlated with poor patient survival. Inhibiting the HIF transcription factors with small molecules is challenging; therefore, we sought to identify genes downstream of HIF-1 that could be targeted to block invasion and metastasis. Creatine kinase brain isoform (CKB) was identified as a highly differentially expressed gene in a screen of HIF-1 wild type and knockout mammary tumor cells derived from a transgenic model of metastatic breast cancer. CKB is a cytosolic enzyme that reversibly catalyzes the phosphorylation of creatine, generating phosphocreatine (PCr) in the forward reaction, and regenerating ATP in the reverse reaction. Creatine kinase activity is inhibited by the creatine analog cyclocreatine (cCr). Loss- and gain-of-function genetic approaches were used in combination with cCr therapy to define the contribution of CKB expression or creatine kinase activity to cell proliferation, migration, invasion, and metastasis in ER-negative breast cancers. CKB was necessary for cell invasion in vitro and strongly promoted tumor growth and lung metastasis in vivo. Similarly, cyclocreatine therapy repressed cell migration, cell invasion, the formation of invadopodia and lung metastasis. Moreover, in common TNBC cell line models, the addition of cCr to conventional cytotoxic chemotherapy agents was either additive or synergistic to repress tumor cell growth.

Dysregulated tumor cell metabolism is a hallmark of cancer progression and therapeutic resistance. In a screen for Hypoxia-Inducible Factor (HIF)-dependent genes regulating metabolism, we identified creatine kinase, brain isoform (CKB) as down-regulated in HIF-1 knockout mammary tumor cells. Creatine kinases (CKs) reversibly catalyze the transfer of a high-energy phosphoryl group from ATP to creatine, generating phosphocreatine in the forward reaction, and ATP in the reverse reaction. CKs are up-regulated in a variety of solid tumors, including ovarian, breast, colon, lung and brain. Knockdown of CKB in the polyoma middle T (PyMT) transgenic mouse model of metastatic breast cancer suppressed the production of intracellular ATP and invasion in vitro, and inhibited metastasis from the mammary gland to the lung in vivo. CK activity is known to be inhibited by cyclocreatine, a creatine kinase substrate that represses CK-dependent generation of ATP from phosphocreatine. When female FVB/Nj mice were injected with wild type PyMT cells in a tail vein assay and then treated with cCr (1g/kg/day, IP), lung metastasis was repressed to the same extent as Ckb gene knockdown. Moreover, when cCr therapy was administered 7 days after tail vein injection, cCr was effective in preventing the transition of lung micrometastases to macrometastases. To explore the role of CK activity in regulating cell proliferation, survival in suspension, cellular metabolism and invasion, we next created CKB loss- and gain-of-function models using human breast cancer cell lines, and compared phenotypes to cCr treatment. Whereas deletion of CKB had no effect on cell proliferation or survival in adherent conditions or in suspension, either deletion of CKB or cCr therapy potently reduced ATP levels and invasive potential in vitro. Preliminary data also indicate that pre-treatment of triple negative breast cancer cell lines with cCr sensitizes cells to doxorubicin. Together, these data suggest that inhibition of CK activity may be effective in treating stage IV breast cancer. We are currently testing whether cCr has anti-metastatic efficacy as a monotherapy, or in combination with conventional chemotherapies, using luciferase-labeled patient-derived xenograft (PDX) models. This work was sponsored by the NIH (CA138488), the Dept. of Defense (BC150640), the METAvivor foundation, and the West Cancer Center in Memphis, TN. Citation Format: Hilaire Barch, Danielle L. Brooks, Raya Krutilina, Luciana P. Schwab, Deanna Parke, Tiffany N. Seagroves. HIF-1-dependent regulation of creatine kinase metabolism promotes breast cancer invasion and metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4511. doi:10.1158/1538-7445.AM2017-4511

Background Hypoxia-inducible factors (HIFs) are well-established mediators of tumor growth, the epithelial to mesenchymal transition (EMT) and metastasis. In several types of solid tumors, including breast cancers, the HIFs play a critical role in maintaining cancer stem cell (CSC) activity. Thus, we hypothesized that HIFs may also regulate transcription of markers of breast CSC activity. One approach to enrich for breast cells with stem-like phenotypes is FACS sorting, in which sub-populations of live cells are gated based on the expression of cell surface antigens, including various integrin subunits. Integrin alpha 6 (ITGA6; CD49f) is routinely used in combination with other integrin subunits to enrich for breast stem cells by FACS. Integrins not only mediate interactions with the extracellular matrix (ECM), but also drive intracellular signaling events that communicate from the tumor microenvironment to inside of the tumor cell to alter phenotypes including migration and invasion. Methods We used two models of metastatic breast cancer (MBC), polyoma middle T (MMTV-PyMT) and MDA-MB-231 cells, to compare the expression of ITGA6 in wild type and knockout (KO) or knockdown cells. Chromatin immunoprecipitation (ChIP) and luciferase reporter assays verified that ITGA6 is a direct HIF transcriptional target. We also used FACS sorting to enrich for CD49f + cells to compare tumorsphere formation, tumor initiating cell activity, invasion and HIF activity relative to CD49fneg or low cells. Knockdown of ITGA6 significantly reduced invasion, whereas re-expression of ITGA6 in the context of HIF knockdown partially rescued invasion. A search of public databases also revealed that ITGA6 expression is an independent prognostic factor of survival in breast cancer patients. Results We report that ITGA6 is a HIF-dependent target gene and that high ITGA6 expression enhances invasion and tumor-initiating cell activities in models of MBC. Moreover, cells that express high levels of ITGA6 are enriched for HIF-1α expression and the expression of HIF-dependent target genes. Conclusions Our data suggest that HIF-dependent regulation of ITGA6 is one mechanism by which sorting for CD49f + cells enhances CSC and metastatic phenotypes in breast cancers. Our results are particularly relevant to basal-like breast cancers which express higher levels of the HIFα subunits, core HIF-dependent target genes and ITGA6 relative to other molecular subtypes. Electronic supplementary material The online version of this article (doi:10.1186/s12943-016-0510-x) contains supplementary material, which is available to authorized users.