Tumor lymphangiogenesis promotes metastatic cancer spread to lymph nodes and beyond. However, the potential remodeling and functionality of tumor-draining lymphatic vessels has remained unclear. Thus, we aimed to develop non-invasive imaging methods for repeated quantitative imaging of lymphatic drainage and of contractile collecting lymphatic vessel function in mice, with colloidal near-infrared (NIR) tracers and a custom fluorescence stereomicroscope specially adapted for NIR sensitive imaging. Using these tools, we quantitatively determined pulse rates and valvular function of collecting lymphatic vessels with high resolution. Unexpectedly, we found that tumor-draining lymphatic vessels in a melanoma footpad model initially were dilated but remained functional, despite lower pulse rates. In two independent tumor models, impaired lymphatic function was detected once metastases were present in draining lymph nodes. Importantly, we found that lymphatic dysfunction, induced by metastatic tumor spread to sentinel lymph nodes, can lead to a rerouting of lymphatic flow away from the metastatic lymph node, via collateral lymphatic vessels, to alternate lymph nodes. These findings might have important clinical implications for the procedure of sentinel lymph node mapping that represents the standard of care for determining prognosis and treatment of melanoma and breast cancer patients.

Tumor-associated macrophages (TAMs) have been implicated in the promotion of breast cancer growth and metastasis, and a strong infiltration by TAMs has been associated with estrogen receptor (ER)-negative tumors and poor prognosis. However, the molecular mechanisms behind these observations are unclear. We investigated macrophage activation in response to co-culture with several breast cancer cell lines (T47D, MCF-7, BT-474, SKBR-3, Cal-51 and MDA-MB-231) and found that high granulocyte colony-stimulating factor (G-CSF) secretion by the triple-negative breast cancer (TNBC) cell line MDA-MB-231 gave rise to immunosuppressive HLA-DRlo macrophages that promoted migration of breast cancer cells via secretion of TGF-α. In human breast cancer samples (n = 548), G-CSF was highly expressed in TNBC (p < 0.001) and associated with CD163+ macrophages (p < 0.0001), poorer overall survival (OS) (p = 0.021) and significantly increased numbers of TGF-α+ cells. While G-CSF blockade in the 4T1 mammary tumor model promoted maturation of MHCIIhi blood monocytes and TAMs and significantly reduced lung metastasis, anti-CSF-1R treatment promoted MHCIIloF4/80hiMRhi anti-inflammatory TAMs and enhanced lung metastasis in the presence of high G-CSF levels. Combined anti-G-CSF and anti-CSF-1R therapy significantly increased lymph node metastases, possibly via depletion of the so-called “gate-keeper” subcapsular sinus macrophages. These results indicate that G-CSF promotes the anti-inflammatory phenotype of tumor-induced macrophages when CSF-1R is inhibited and therefore caution against the use of M-CSF/CSF-1R targeting agents in tumors with high G-CSF expression.

Historically, lymphatic vessels were considered passive participants in tumor metastasis by simply providing channels for tumor cells to transit to draining lymph nodes. The discovery of several key lymphatic-specific molecular markers and an increased availability of in vitro and in vivo experimental systems to study lymphatic biology have however highlighted a much more complex, active role for the lymphatic vasculature in metastatic tumor spread. This review will briefly describe the lymphatic system and lymphangiogenesis and then focus on the role of the lymphatic system in cancer metastasis. The progression of our understanding from the lymphatic system as a somewhat passive conduit for metastasis to an active participant in metastatic tumor dissemination, regulated by a complex array of lymphangiogenic factors, chemokines, and immune cell subsets, will be described.

Formalin-fixed, paraffin-embedded (FFPE), biobanked tissue samples offer an invaluable resource for clinical and biomarker research. Here, we developed a pressure cycling technology (PCT)-SWATH mass spectrometry workflow to analyze FFPE tissue proteomes and applied it to the stratification of prostate cancer (PCa) and diffuse large B-cell lymphoma (DLBCL) samples. We show that the proteome patterns of FFPE PCa tissue samples and their analogous fresh-frozen (FF) counterparts have a high degree of similarity and we confirmed multiple proteins consistently regulated in PCa tissues in an independent sample cohort. We further demonstrate temporal stability of proteome patterns from FFPE samples that were stored Abbreviations BPH, benign prostatic hyperplasia; CRYAB, crystallin alpha Bbetween 1 and 15 years in a biobank and show a high degree of the proteome pattern similarity between two types of histological regions in small FFPE samples, that is, punched tissue biopsies and thin tissue sections of micrometer thickness, despite the existence of a certain degree of biological variations. Applying the method to two independent DLBCL cohorts, we identified myeloperoxidase, a peroxidase enzyme, as a novel prognostic marker. In summary, this study presents a robust proteomic method to analyze bulk and biopsy FFPE tissues and reports the first systematic comparison of proteome maps generated from FFPE and FF samples. Our data demonstrate the practicality and superiority of FFPE over FF samples for proteome in biomarker discovery. Promising biomarker candidates for PCa and DLBCL have been discovered.

Cell-intrinsic effects such as induction of apoptosis and/or inhibition of cell proliferation have been proposed as the major antitumor responses to histone deacetylase inhibitors (HDACi). These compounds can also mediate immune-modulatory effects that may contribute to their anticancer effects. However, HDACi can also induce anti-inflammatory, and potentially immunosuppressive, outcomes. We therefore sought to clarify the role of the immune system in mediating the efficacy of HDACi in a physiologic setting, using preclinical, syngeneic murine models of hematologic malignancies and solid tumors. We showed an intact immune system was required for the robust anticancer effects of the HDACi vorinostat and panobinostat against a colon adenocarcinoma and two aggressive models of leukemia/lymphoma. Importantly, although HDACi-treated immunocompromised mice bearing established lymphoma succumbed to disease significantly earlier than tumor bearing, HDACitreated wild-type (WT) mice, treatment with the conventional chemotherapeutic etoposide equivalently enhanced the survival of both strains. IFN-g and tumor cell signaling through IFN-gR were particularly important for the anticancer effects of HDACi, and vorinostat and IFN-g acted in concert to enhance the immunogenicity of tumor cells. Furthermore, we show that a combination of vorinostat with a-galactosylceramide (a-GalCer), an IFN-g-inducing agent, was significantly more potent against established lymphoma than vorinostat treatment alone. Intriguingly, B cells, but not natural killer cells or CD8 þ T cells, were implicated as effectors of the vorinostat antitumor immune response. Together, our data suggest HDACi are immunostimulatory during cancer treatment and that combinatorial therapeutic regimes with immunotherapies should be considered in the clinic. Cancer Res; 73(24); 7265-76. Ó2013 AACR.