Quantitative Analysis of Vascular Endothelial Growth Factor in Liver Metastases from Pancreatic Carcinoma as a Predictor of Chemotherapeutic Effect and Prognosis

Katsunobu Tawada, Takeshi Ishihara, Akitoshi Kobayashi, Taketo Yamaguchi, Toshio Tsuyuguchi, Masato Matsuyama and Osamu Yokosuka

Purpose: In pancreatic carcinoma, vascular endothelial growth factor (VEGF) expression at the primary site has been suggested to be a prognostic parameter. We quantitatively analyzed VEGF expression in liver metastases from pancreatic carcinoma and examined the correlation among VEGF expression in liver metastases, clinicopathologic factors, and clinical outcome.

Experimental Design: The subjects consisted of 23 patients with pancreatic adenocarcinoma who had liver metastases and were treated with S-1 and gemcitabine as the first-line treatment. VEGF expression was quantitated by enzyme immunoassay in biopsy specimens of liver metastases and nontumorous liver tissue, and in plasma. In 10 of the 23 patients, VEGF expression was also quantitated in biopsy specimens of the primary pancreatic tumor. All samples were collected before treatment.

Results: The VEGF level in nontumorous liver tissue was 36.6 ± 10.0 pg/mg protein versus 376.8 ± 106.1 pg/mg protein in liver metastases (P = 0.0016). Pretreatment VEGF levels in plasma and in primary pancreatic carcinoma did not correlate with VEGF levels in the corresponding liver metastases. The median VEGF level in liver metastases (138.9 pg/mg protein) was used as the cutoff value between high and low VEGF expression in liver metastases. Patients showing high VEGF expression had a significantly longer progression-free survival and overall survival than patients showing low VEGF expression in liver metastases (P = 0.0219 and P = 0.0074, respectively).

Conclusions: Evaluation of VEGF levels in liver metastases might be useful in assessing the prognosis of patients with metastatic pancreatic carcinoma who are under systemic chemotherapy.

Invasion and metastasis: stem cells, screens and survival. Conference on Invasion and Metastasis

Nicolas Tapon & Ulrike Ziebold

Mortality in cancer patients is often caused by tumour recurrence or metastasis, rather than by the primary tumour. In order to understand cancer, it is crucial to elucidate how cells invade and survive in new environments, a process known as metastasis (Fig 1). Despite years of research, few proteins have been confirmed experimentally to induce metastasis. Hence, we need to improve screening technologies by linking them to migration, invasion and three-dimensional-survival assays, and/or to use more sophisticated imaging strategies, in order to uncover more accurate prognostic markers and improved therapies. The International Conference on Invasion and Metastasis at the Max Delbrück Center for Molecular Medicine provided an intriguing outlook on these pressing issues.

Macrophage-Derived SPARC Bridges Tumor Cell-Extracellular Matrix Interactions toward Metastasis

Sabina Sangaletti, Emma Di Carlo, Silvia Gariboldi, Silvia Miotti, Barbara Cappetti, Mariella Parenza, Cristiano Rumio, Rolf A. Brekken, Claudia Chiodoni and Mario P. Colombo

Other than genetic imprinting and epithelial to mesenchymal transition, cancer cells need interaction with the nearby stroma toward metastasis. Secreted protein acidic and rich in cysteine (SPARC) is a matricellular protein known to regulate extracellular matrix (ECM) deposition and cell-ECM interaction. Gene expression profiles associate SPARC to malignant progression. Using reciprocal bone marrow chimeras between SPARC knockout and wild-type mice, we show that SPARC produced by inflammatory cells is necessary for spontaneous, but not experimental, i.v. metastasis. Macrophage-derived SPARC induces cancer cell migration and enhances their migration to other ECM proteins at least through vβ5 integrin. Indeed, RNA interference knockdown of β5 integrin expression reduces cell migration in vitro and metastasis in vivo. Together these results show that macrophage-derived SPARC takes part in metastasis, acting at the step of integrin-mediated migration of invasive cells.

The ubiquitin ligase Siah2 regulates tumorigenesis and metastasis by HIF-dependent and -independent pathways

Jianfei Qi, Koh Nakayama, Supriya Gaitonde, James S. Goydos, Stan Krajewski, Alexey Eroshkin, Dafna Bar-Sagi, David Bowtell, and Ze'ev Ronai

The ubiquitin ligase Siah2 has been shown to regulate prolyl hydroxylase 3 (PHD3) stability with concomitant effect on HIF-1α availability. Because HIF-1α is implicated in tumorigenesis and metastasis, we used SW1 mouse melanoma cells, which develop primary tumors with a propensity to metastasize, in a syngeneic mouse model to assess a possible role for Siah2 in these processes. Inhibiting Siah2 activity by expressing a peptide designed to outcompete association of Siah2-interacting proteins reduced metastasis through HIF-1α without affecting tumorigenesis. Conversely, inhibiting Siah2 activity by means of a dominant-negative Siah2 RING mutant primarily reduced tumorigenesis through the action of Sprouty 2, a negative regulator of Ras signaling. Consistent with our findings, reduced expression of PHD3 and Sprouty2 was observed in more advanced stages of melanoma tumors. Using complementary approaches, our data establish the role of Siah2 in tumorigenesis and metastasis by HIF-dependent and -independent mechanisms.

Tumor-Targeted Interferon-α Delivery by Tie2-Expressing Monocytes Inhibits Tumor Growth and Metastasis

Michele De Palma, Roberta Mazzieri, Letterio S. Politi, Ferdinando Pucci, Erika Zonari, Giovanni Sitia, Stefania Mazzoleni, Davide Moi, Mary Anna Venneri, Stefano Indraccolo, Andrea Falini, Luca G. Guidotti, Rossella Galli, and Luigi Naldini

The use of type I interferons (IFNs) in cancer therapy has been limited by ineffective dosing and significant toxicity. Here, we exploited the tumor-homing ability of proangiogenic Tie2-expressing monocytes (TEMs) to deliver IFN-α to tumors. By transplanting hematopoietic progenitors transduced with a Tie2 promoter/enhancer-driven Ifna1 gene, we turned TEMs into IFN-α cell vehicles that efficiently targeted the IFN response to orthotopic human gliomas and spontaneous mouse mammary carcinomas and obtained significant antitumor responses and near complete abrogation of metastasis. TEM-mediated IFN-α delivery inhibited tumor angiogenesis and activated innate and adaptive immune cells but did not impair myelopoiesis and wound healing detectably. These results illustrate the therapeutic potential of gene- and cell-based IFN-α delivery and should allow the development of IFN treatments that more effectively treat cancer.

Suppression of Prostate Cancer Nodal and Systemic Metastasis by Blockade of the Lymphangiogenic Axis

Jeremy B. Burton, Saul J. Priceman, James L. Sung, Ebba Brakenhielm, Dong Sung An, Bronislaw Pytowski, Kari Alitalo and Lily Wu

Lymph node involvement denotes a poor outcome for patients with prostate cancer. Our group, along with others, has shown that initial tumor cell dissemination to regional lymph nodes via lymphatics also promotes systemic metastasis in mouse models. The aim of this study was to investigate the efficacy of suppressive therapies targeting either the angiogenic or lymphangiogenic axis in inhibiting regional lymph node and systemic metastasis in subcutaneous and orthotopic prostate tumor xenografts. Both androgen-dependent and more aggressive androgen-independent prostate tumors were used in our investigations. Interestingly, we observed that the threshold for dissemination is lower in the vascular-rich prostatic microenvironment compared with subcutaneously grafted tumors. Both vascular endothelial growth factor-C (VEGF-C) ligand trap (sVEGFR-3) and antibody directed against VEGFR-3 (mF4-31C1) significantly reduced tumor lymphangiogenesis and metastasis to regional lymph nodes and distal vital organs without influencing tumor growth. Conversely, angiogenic blockade by short hairpin RNA against VEGF or anti–VEGFR-2 antibody (DC101) reduced tumor blood vessel density, significantly delayed tumor growth, and reduced systemic metastasis, although it was ineffective in reducing lymphangiogenesis or nodal metastasis. Collectively, these data clarify the utility of vascular therapeutics in prostate tumor growth and metastasis, particularly in the context of the prostate microenvironment. Our findings highlight the importance of lymphangiogenic therapies in the control of regional lymph node and systemic metastasis.