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Colorectal cancer (CRC) related death has often been attributed to the presence of metastatic disseminated disease. A concise understanding of the molecular mechanism(s) that drive metastatic progression is therefore needed but has thus far been hampered by the limited number of CRC mouse models that progress toward this disease stage. In addition, preclinical evaluation of therapeutic modalities aimed at managing metastatic disease also rests on the availability of relevant in vivo models that faithfully recapitulate the key molecular features of metastatic human CRC. To overcome these limitations, we have recently developed methodologies that enable the study of CRC progression at relevant orthotopic sites. Here, we provide a detailed methodology that describes the injection of CRC derived cell lines and organoids directly into the colorectal mucosa. This results in the growth of a single tumor mass within the colon, that can spontaneously metastasize to the liver. Furthermore, we also present a surgical procedure to directly inject cells into the portal venous circulation to induce CRC tumor growth in the liver without the requirement of a primary tumor.

The proto-oncogenes ETV1, ETV4 and ETV5 encode transcription factors in the E26 transformation-specific (ETS) family, which includes the most frequently rearranged and overexpressed genes in prostate cancer. Despite being critical regulators of development, little is known about their post-translational regulation. Here we identify the ubiquitin ligase COP1 (also known as RFWD2) as a tumour suppressor that negatively regulates ETV1, ETV4 and ETV5. ETV1, which is mutated in prostate cancer more often, was degraded after being ubiquitinated by COP1. Truncated ETV1 encoded by prostate cancer translocation TMPRSS2:ETV1 lacks the critical COP1 binding motifs and was 50-fold more stable than wild-type ETV1. Almost all patient translocations render ETV1 insensitive to COP1, implying that this confers a selective advantage to prostate epithelial cells. Indeed, COP1 deficiency in mouse prostate elevated ETV1 and produced increased cell proliferation, hyperplasia, and early prostate intraepithelial neoplasia. Combined loss of COP1 and PTEN enhanced the invasiveness of mouse prostate adenocarcinomas. Finally, rare human prostate cancer samples showed hemizygous loss of the COP1 gene, loss of COP1 protein, and elevated ETV1 protein while lacking a translocation event. These findings identify COP1 as a tumour suppressor whose downregulation promotes prostatic epithelial cell proliferation and tumorigenesis.

Chronic inflammation of the colon increases cancer development risk. Ulcerative colitis, characterized by excessive inflammation initiated by innate immune cells and exacerbated by a dysregulation in adaptive immunity, can give rise to colitis-associated colon cancer (CAC). Whereas overactivity of effector T cells and loss of immunosuppressive cells are hallmarks of ulcerative colitis, the opposite is true for CAC, with CAC tumors exhibiting a lack of effector T cell infiltration and a preponderence of immunosuppressive Treg cells and myeloid-derived suppressor cells (MDSCs). Recently, hypoxia has been identified as a potential driver in the pathogenesis of ulcerative colitis, with hypoxia persisting upon progression to CAC tumor formation. We have previously demonstrated that (i) hypoxia generates an immunosuppressive tumor microenvironment that limits effector T cell infiltration and activation, (ii) OMX, a first-in-class anti-cancer therapy designed to reverse tumor hypoxia to enhance immunotherapeutic efficacy, accumulates in preclinical rodent and spontaneous canine tumors and reduces tumor hypoxia, and (iii) OMX promotes effector T cell infiltration, reduces Treg cells, and enhances checkpoint inhibitor efficacy, resulting in greater tumor control. Given that CAC tumors are hypoxic and immunosuppressed, we hypothesized that hypoxia drives CAC tumor immunosuppression, and accordingly, that reversal of hypoxia with OMX may restore immunosensitivity and elicit an anti-tumor response. Here, using a chemically induced mouse model of CAC generated by administering azoxymethane (AOM) followed by repeated cycles of dextran sulfate sodium (DSS) exposure, we show that OMX treatment exhibits anti-tumor efficacy in advanced CAC tumors. We characterized CAC tumor progression from 8 to 12 weeks post-tumor induction, and confirmed previous reports that advanced CAC tumors are indeed hypoxic, and that immunosuppressive Treg cells and MDSCs are more abundant in CAC tumors relative to adjacent normal mucosa or control non-AOM/DSS-treated colons. Moreover, we observed a negative correlation between hypoxia and CD8+ T cell infiltration into CAC tumors. OMX single agent treatment reduced both CAC tumor number and total CAC tumor burden. Of note, OMX treatment reversed colon length shortening that was characteristic of tumor-bearing mice, indicative of a restoration of colon crypt regeneration and hence normal colon biology. Investigations into the immunological mechanism(s) responsible for OMX anti-tumor efficacy are currently underway. Taken together, our data suggest that OMX, by delivering oxygen to hypoxic CAC tumor regions, may be sufficient to induce an immunological change in the CAC tumor microenvironment from an immunosuppressive to an immunopermissive state, leading to tumor responses and a restoration of normal physiology. Citation Format: Kevin G. Leong, Yuqiong Pan, Changan Guo, Padmini Narayanan, Jonathan A. Winger, Stephen P. Cary, Natacha Le Moan, Ana Krtolica. Reversal of advanced colitis-associated colon cancer by OMX, a novel oxygen carrier that immunosensitizes the hypoxic tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1744.

Several ongoing clinical studies are designed to test the efficacy of antiangiogenic therapies in the adjuvant setting, where the goal is to increase the cure rate in patients who have just undergone surgical resection of all visible disease. Tumors depend on angiogenesis to support their growth and progression and blockade of this process has proven to be a valid strategy for treating multiple types of advanced metastatic cancer. However, results from the first of these clinical adjuvant studies were disappointing, stimulating extensive debate as to the potential of this approach. It will require additional clinical studies before we realize whether the effects of angiogenic blockade are durable, and if they are able to cure a subset of patients with early stage cancer.

Deciphering metastatic routes is critically important as metastasis is a primary cause of cancer mortality. In colorectal cancer (CRC), it is unknown whether liver metastases derive from cancer cells that first colonize intestinal lymph nodes, or whether such metastases can form without prior lymph node involvement. A lack of relevant metastatic CRC models has precluded investigations into metastatic routes. Here we describe a metastatic CRC mouse model and show that liver metastases can manifest without a lymph node metastatic intermediary. Colorectal tumours transplanted onto the colonic mucosa invade and metastasize to specific target organs including the intestinal lymph nodes, liver and lungs. Importantly, this metastatic pattern differs from that observed following caecum implantation, which invariably involves peritoneal carcinomatosis. Anti-angiogenesis inhibits liver metastasis, yet anti-lymphangiogenesis does not impact liver metastasis despite abrogating lymph node metastasis. Our data demonstrate direct hematogenous spread as a dissemination route that contributes to CRC liver malignancy.

Androgen deprivation is currently a standard-of-care, first-line therapy for prostate cancer in the United States. Although this regimen effectively regresses androgen-dependent disease, relapse often occurs in an androgen-independent manner and is associated with poor prognosis. Such castration-resistant prostate cancer represents a major clinical challenge, and the mechanisms underlying castration resistance are not fully understood. Epithelial–mesenchymal transition (EMT) is a key developmental process and has also been implicated in cancer metastasis and therapeutic resistance in recent years. However, the factors contributing to EMT in human cancers remain unclear. Here, we show that both normal mouse prostate tissue and human LuCaP35 prostate tumor explants display an EMT as well as increased stem cell–like features following androgen deprivation. Importantly, we observed similar changes in mesenchymal features in prostate tumors from patients treated with androgen-deprivation therapy. In addition, we have delineated a feedback loop involving the androgen receptor and the Zeb1 transcription factor that seems to mediate this transition. In summary, we show for the first time that androgen deprivation induces EMT in both normal prostate and prostate cancer, revealing a potentially important consequence of a standard-of-care treatment for prostate cancer. This finding could have significant implications for second-line treatment strategies in this clinical setting. Cancer Res; 72(2); 527–36. ©2011 AACR.

The Notch family of transmembrane receptors are important mediators of cell fate determination. Accordingly, Notch signaling is intimately involved in the development of numerous tissues. Recent findings have highlighted a critical role for Notch signaling in normal prostate development. Notch signaling is required for embryonic and postnatal prostatic growth and development, for proper cell lineage specification within the prostate, as well as for adult prostate maintenance and regeneration following castration and hormone replacement. Evidence for Notch as a regulator of prostate cancer development, progression, and metastasis has also emerged. This review summarizes our current understanding of the role of Notch pathway elements, including members of the Jagged, Delta-like, hairy/enhancer-of-split, and hairy/enhancer-of-split related with YRPW motif families, in prostate development and tumorigenesis. Data supporting Notch pathway elements as oncogenes and tumor suppressors in prostate tumors, as well as data implicating Notch receptors and ligands as potential markers of normal prostate stem/progenitor cells and prostate cancer stem/initiating cells, are also presented.

Aberrant expression of Jagged1 and Notch1 are associated with poor outcome in breast cancer. However, the reason that Jagged1 and/or Notch overexpression portends a poor prognosis is unknown. We identify Slug, a transcriptional repressor, as a novel Notch target and show that elevated levels of Slug correlate with increased expression of Jagged1 in various human cancers. Slug was essential for Notch-mediated repression of E-cadherin, which resulted in β-catenin activation and resistance to anoikis. Inhibition of ligand-induced Notch signaling in xenografted Slug-positive/E-cadherin–negative breast tumors promoted apoptosis and inhibited tumor growth and metastasis. This response was associated with down-regulated Slug expression, reexpression of E-cadherin, and suppression of active β-catenin. Our findings suggest that ligand-induced Notch activation, through the induction of Slug, promotes tumor growth and metastasis characterized by epithelial-to-mesenchymal transition and inhibition of anoikis.

Angiogenesis is a crucial event in the survival and progression of solid tumors. To determine whether angiogenesis in acute myeloid leukemia (AML) is an intrinsic property of leukemic cells, the vascularity of bone marrow biopsies was determined. Bone marrow vascularity in newly diagnosed or post-chemotherapy AML patients was increased 4-fold (P < 0.01) and 8.7-fold (P < 0.01), respectively, relative to controls. Vascular endothelial growth factor (VEGF) expression by AML blast cells was assessed by immunohistochemistry, and bone marrow cell supernatants were assayed for secretion of VEGF, fibroblast growth factor-2 (FGF-2), and endostatin by enzyme-linked immunosorbent assay. Diffuse cytoplasmic and strong extracellular VEGF immunoreactivity was seen in bone marrow aspirates from AML patients, but not controls. In contrast, there was no difference in the levels of VEGF, FGF-2, and endostatin secreted by mononuclear cells cultured from bone marrows of AML patients compared to normal controls following two days of culture in vitro. Total angiogenic potential of bone marrow cell supernatants was assessed by endothelial sprouting in vitro and by a chick chorioallantoic membrane assay. No differences were found between 2-day conditioned medium from normal and AML bone marrow mononuclear cells in either assay. Our data show a discrepancy between bone marrow vascularity and VEGF expression in vivo and VEGF expression and angiogenesis from 2-day conditioned medium ex vivo. This suggests that angiogenesis in AML likely represents a response to microenvironmental factors in vivo, rather than being an intrinsic property of leukemic cells.

Median followup was 491 days (min 19 and max 1115). There were 5 relapses and all were elsewhere failures. 2 died of intercurrent disease and 92 were alive with no evidence of disease. Conclusions: The initial data seem show good concordance between physicians and nurses and patients in about 50% of the patients. The presence of seroma and number of re-excisions seem to have an impact on cosmesis. We plan to continue this study by including surgeons in the cosmesis evaluation. The data required breast cup size, laterality and quadrant will be presented at the MTG. Impact of chemotherapy will also be evaluated.