CCL18 from tumor-associated macrophages promotes angiogenesis in breast cancer.

The infiltration of tumor-associated macrophages (TAMs) is associated with extensive angiogenesis, which contributes to a poor prognosis in breast cancer. However, anti-angiogenic therapy with VEGF-specific monotherapy has been unsuccessful in treating breast cancer, and the molecular mechanisms associated with chemoresistance remain unclear. Here, we investigated whether CCL18, a chemokine produced by TAMs, can stimulate angiogenesis in breast cancer, as well as the underlying mechanisms. Double immunohistochemical staining for CCL18 and CD34/CD31/vWF was performed in 80 breast cancer samples to study the correlation between CCL18+ TAMs and microvascular density (MVD). Cocultures of TAMs with human umbilical vein endothelial cells (HUVECs) were used to model the inflammatory microenvironment, and CCL18-induced angiogenesis was evaluated both in vitro and in vivo. We demonstrated that CCL18+ TAM infiltration positively associated with MVD in breast cancer samples, which was correlated with tumor metastasis and poor prognosis. We confirmed, both in vitro and in vivo, that CCL18 and VEGF synergistically promoted endothelial cell migration and angiogenesis. Conversely, blocking CCL18 or VEGF with neutralizing antibodies synergistically inhibited the promigratory effects of TAMs. Silencing PITPNM3, a putative CCL18 receptor, on the surface of HUVECs abrogated CCL18-mediated promigration and the enhancement of HUVEC tube formation, independently of VEGFR signaling. Moreover, CCL18 exposure induced the endothelial-mesenchymal transformation and activated ERK and Akt/GSK-3ß/Snail signaling in HUVECs, thereby contributing to its pro-angiogenic effects. In conclusion, our findings suggest that CCL18 released from TAMs promotes angiogenesis and tumor progression in breast cancer; thus, CCL18 may serve as a novel target for anti-angiogenic therapies.

Targeted delivery of PLK1-siRNA by ScFv suppresses Her2+ breast cancer growth and metastasis.

A major obstacle to developing small interfering RNAs (siRNAs) as cancer drugs is their intracellular delivery to disseminated cancer cells. Fusion proteins of single-chain fragmented antibodies (ScFvs) and positively charged peptides deliver siRNAs into specific target cells. However, the therapeutic potential of ScFv-mediated siRNA delivery has not been evaluated in cancer. Here, we tested whether Polo-like kinase 1 (PLK1) siRNAs complexed with a Her2-ScFv-protamine peptide fusion protein (F5-P) could suppress Her2(+) breast cancer cell lines and primary human cancers in orthotopic breast cancer models. PLK1-siRNAs transferred by F5-P inhibited target gene expression, reduced proliferation, and induced apoptosis of Her2(+) breast cancer cell lines and primary human cancer cells in vitro without triggering an interferon response. Intravenously injected F5-P/PLK1-siRNA complexes concentrated in orthotopic Her2(+) breast cancer xenografts and persisted for at least 72 hours, leading to suppressed PLK1 gene expression and tumor cell apoptosis. The intravenously injected siRNA complexes retarded Her2(+) breast tumor growth, reduced metastasis, and prolonged survival without evident toxicity. F5-P-mediated delivery of a cocktail of PLK1, CCND1, and AKT siRNAs was more effective than an equivalent dose of PLK1-siRNAs alone. These data suggest that F5-P could be used to deliver siRNAs to treat Her2(+) breast cancer.

Simultaneous delivery of siRNA and paclitaxel via a "two-in-one" micelleplex promotes synergistic tumor suppression.

Combination of two or more therapeutic strategies with different mechanisms can cooperatively prohibit cancer development. Combination of chemotherapy and small interfering RNA (siRNA)-based therapy represents an example of this approach. Hypothesizing that the chemotherapeutic drug and the siRNA should be simultaneously delivered to the same tumoral cell to exert their synergistic effect, the development of delivery systems that can efficiently encapsulate two drugs and successfully deliver payloads to targeted sites via systemic administration has proven to be challenging. Here, we demonstrate an innovative "two-in-one" micelleplex approach based on micellar nanoparticles of a biodegradable triblock copolymer poly(ethylene glycol)-b-poly(ε-caprolactone)-b-poly(2-aminoethyl ethylene phosphate) to systemically deliver the siRNA and chemotherapeutic drug. We show clear evidence that the micelleplex is capable of delivering siRNA and paclitaxel simultaneously to the same tumoral cells both in vitro and in vivo. We further demonstrate that systemic administration of the micelleplex carrying polo-like kinase 1 (Plk1) specific siRNA and paclitaxel can induce a synergistic tumor suppression effect in the MDA-MB-435s xenograft murine model, requiring a thousand-fold less paclitaxel than needed for paclitaxel monotherapy delivered by the micelleplex and without activation of the innate immune response or generation of carrier-associated toxicity.