Hepatic RF ablation induces not only a local periablational inflammatory zone but also more global proliferative effects on the liver. These IL-6- and/or c-met-mediated changes could potentially account for some of the local and distant tumor recurrence observed after treatment.

Purpose To compare both periablational and systemic effects of two mechanistically different types of ablation: thermal radiofrequency (RF) ablation and electroporative ablation with irreversible electroporation (IRE) in appropriately selected animal models. Materials and Methods Animal experiments were performed according to a protocol approved by the Animal Care Committee of Hebrew University. Female C57BL/6 mice (n = 165) were randomized to undergo either RF or IRE ablation of noncancerous normal liver. The inflammatory response, cell proliferation, interleukin 6 (IL-6) levels, and intactness of vessels in the liver were assessed at 6, 12, and 24 hours and at 3, 7, and 14 days after ablation (n = 122 for mechanistic experiments). Systemic effects were then assessed by comparing tumor formation in an Mdr2-knockout (KO) mouse model (n = 15) and tumor growth in a remote BNL 1ME hepatoma xenograft tumor (n = 28). Results were averaged and evaluated by using two-tailed t tests. Results Although RF ablation was associated with a well-defined periablational inflammatory rim, for IRE, the infiltrate penetrated the ablation zone, largely along persistently patent vessels. Peak IL-6 levels (6 hours after ablation) were 10 and three times higher than at baseline for IRE and RF, respectively (P < .03). Mdr2-KO mice that were treated with IRE ablation had more tumors that were 3 mm or larger than mice treated with RF ablation or sham operation (mean, 3.6 ± 1.3 [standard deviation] vs 2.4 ± 1.1 and 2.2 ± 0.8, respectively; P < .05 for IRE vs both RF ablation and sham operation). For BNL 1ME tumors, both RF and IRE liver ablation reduced tumor growth, with a greater effect noted for IRE (1329 mm(3) ± 586 and 819 mm(3) ± 327 vs 2241 mm(3) ± 548 for sham operation; P < .05) that was accompanied by more infiltrating lymphocytes compared with sham operation (7.6 cells per frame ± 1.9 vs 11.2 ± 2.1 vs 0.3 ± 0.1; P < .05). Conclusion Persistent patency of vasculature within the coagulated zone from IRE increases the area and accumulation of infiltrative cells that is associated with a higher serum IL-6 level than RF ablation. These local changes of IRE induce more robust systemic effects, including both tumorigenic and immunogenic effects. (©) RSNA, 2016 Online supplemental material is available for this article.

CXCR4 is a key player in the retention and survival of human acute myeloid leukemia (AML) blasts in the bone marrow (BM) microenvironment. We studied the effects of the CXCR4 antagonist BL-8040 on the survival of AML blasts, and investigated the molecular mechanisms by which CXCR4 signaling inhibition leads to leukemic cell death. Treatment with BL-8040 induced the robust mobilization of AML blasts from the BM. In addition, AML cells exposed to BL-8040 underwent differentiation. Furthermore, BL-8040 induced the apoptosis of AML cells in vitro and in vivo. This apoptosis was mediated by the upregulation of miR-15a/miR-16-1, resulting in downregulation of the target genes BCL-2, MCL-1 and cyclin-D1. Overexpression of miR-15a/miR-16-1 directly induced leukemic cell death. BL-8040-induced apoptosis was also mediated by the inhibition of survival signals via the AKT/ERK pathways. Importantly, treatment with a BCL-2 inhibitor induced apoptosis and act together with BL-8040 to enhance cell death. BL-8040 also synergized with FLT3 inhibitors to induce AML cell death. Importantly, this combined treatment prolonged the survival of tumor-bearing mice and reduced minimal residual disease in vivo. Our results provide a rationale to test combination therapies employing BL-8040 and BCL-2 or FLT3 inhibitors to achieve increased efficacy of these agents.

Purpose:To compare hepatocellular carcinoma (HCC) development after radiofrequency (RF) ablation, partial surgical hepatectomy, and a sham operation and to inhibit HCC recurrence after RF ablation in a mouse model of spontaneously forming HCC in the setting of chronic inflammation (ie, the MDR2 knockout model). Materials and Methods:Animal experiments were performed according to an approved animal care committee protocol. The authors compared the survival of MDR2 knockout mice (an inflammation-induced HCC model) that underwent RF ablation, 35% partial hepatectomy (ie, left lobectomy), or a sham operation (controls) by using Kaplan-Meier survival curve analysis. Tumor load and tumor frequency in mice that underwent sham operation were further compared with those of mice treated with RF ablation at 1 month after therapy by using a two-tailed Student t test. Liver slices from mice treated with RF ablation were stained for a2smooth muscle actin and Ki-67 to establish the role of liver regeneration in the tumorigenic effect of RF ablation. Finally, tumor load and tumor incidence were evaluated in mice treated with a c-met inhibitor after RF ablation by using the Mann-Whitney U test. Results:Ablation of 3.5% 6 0.02 of the MDR2 knockout mice liver induced increased tumor load (P = .007) and reduced survival (P = .03) in comparison to that of controls, with no significant difference to the 10-fold volume removal of partial hepatectomy. Seven days after RF treatment, the border zone of the coagulation zone was surrounded by a2smooth muscle actin-positive activated myofibroblasts. A significant elevation of hepatocyte proliferation was also seen 7 days after RF ablation in the distant liver (ablated lobe: P = .003; untreated lobe: P = .02). A c-met inhibitor significantly attenuated HCC development in MDR2 knockout mice treated with RF ablation (P = .001). Conclusion:Liver regeneration induced by RF ablation facilitates cmet/hepatocyte growth factor axis-dependent HCC tumor formation after treatment in the MDR2 knockout model. Blockage of the c-met/hepatocyte growth factor axis attenuates HCC recurrence, raising the potential for therapeutic intervention to reverse this potentially deleterious tumorigenic effect.q RSNA, 2015

To compare hepatocellular carcinoma (HCC) development after radiofrequency (RF) ablation, partial surgical hepatectomy, and a sham operation and to inhibit HCC recurrence after RF ablation in a mouse model of spontaneously forming HCC in the setting of chronic inflammation (ie, the MDR2 knockout model). Materials and Methods: Animal experiments were performed according to an approved animal care committee protocol. The authors compared the survival of MDR2 knockout mice (an inflammation-induced HCC model) that underwent RF ablation, 35% partial hepatectomy (ie, left lobectomy), or a sham operation (controls) by using Kaplan-Meier survival curve analysis. Tumor load and tumor frequency in mice that underwent sham operation were further compared with those of mice treated with RF ablation at 1 month after therapy by using a two-tailed Student t test. Liver slices from mice treated with RF ablation were stained for a2smooth muscle actin and Ki-67 to establish the role of liver regeneration in the tumorigenic effect of RF ablation. Finally, tumor load and tumor incidence were evaluated in mice treated with a c-met inhibitor after RF ablation by using the Mann-Whitney U test. Results: Ablation of 3.5% 6 0.02 of the MDR2 knockout mice liver induced increased tumor load (P = .007) and reduced survival (P = .03) in comparison to that of controls, with no significant difference to the 10-fold volume removal of partial hepatectomy. Seven days after RF treatment, the border zone of the coagulation zone was surrounded by a2smooth muscle actin-positive activated myofibroblasts. A significant elevation of hepatocyte proliferation was also seen 7 days after RF ablation in the distant liver (ablated lobe: P = .003; untreated lobe: P = .02). A c-met inhibitor significantly attenuated HCC development in MDR2 knockout mice treated with RF ablation (P = .001). Conclusion: Liver regeneration induced by RF ablation facilitates cmet/hepatocyte growth factor axis-dependent HCC tumor formation after treatment in the MDR2 knockout model. Blockage of the c-met/hepatocyte growth factor axis attenuates HCC recurrence, raising the potential for therapeutic intervention to reverse this potentially deleterious tumorigenic effect.