Immunocytes as a Biocarrier to Delivery Therapeutic and Imaging Contrast Agents to Tumors

Radiotherapy for cancer treatment has been used for primary or adjuvant treatment in many types of cancer, and approximately half of all cancer patients are undergoing radiation. However, ionizing radiation exposure induces genetic alterations in cancer cells and results in recruitment of monocytes/macrophages by triggering signals released from these cells. Using this characteristic of monocytes/macrophages, we have attempted to develop a biocarrier loading radiosensitizing anticancer agents that can lead to enhance the therapeutic effect of radiation in cancer treatment. The aim of this study is to demonstrate the proof of this concept. THP-1 labeled with Qdot 800 or iron oxide (IO) effectively migrated into tumors of subcutaneous mouse model and increased recruitment after ionizing radiation. Functionalized liposomes carrying a radiosensitizing anticancer agent, doxorubicin, are successfully loaded in THP-1 (THP-1-LP-Dox) with reduced cytotoxicity, and THP-1-LP-Dox also was observed in tumors after intravenous administration. Here, we report that monocytes/macrophages as a biocarrier can be used as a selective tool for amplification of the therapeutic effects on radiotherapy for human cancer treatment

Enhancement of Radiotherapeutic Efficacy by Paclitaxel-Loaded pH-Sensitive Block Copolymer Micelles

Radiotherapy (RT) is a major modality for cancer treatment, but its efficacy is often compromised by the resistance caused by tumor-specific microenvironment including acidosis and hypoxia. For an effective RT, concurrent administration of radiosensitizer with RT has been emphasized. However, most anticancer agents enhancing radiotherapeutic efficacy have obstacles such as poor solubility and severe toxicity. Paclitaxel (PTX), a well-known radiosensitizer, is insoluble in water and needs toxic solvent like Cremophor EL. Nanomaterials in drug delivery systems have been utilized for improving the drawbacks of anti-cancer drugs. Solubilization, tumor accumulation, and toxicity attenuation of drug by nanomaterials are suitable for enhancement of radiotherapeutic efficacy. In this study, PTX was incorporated into pH-sensitive block copolymer micelle (psm-PTX), polyethylene glycol-graft-poly(β-amino ester), and preclinically evaluated for its effect on RT. The size of psm-PTX was 125.7±4.4 nm at pH 7.4. psm-PTX released PTX rapidly in the acidic condition (pH 6.5), while it was reasonably stable in the physiologic condition (pH 7.4). The clonogenic assay showed that psm-PTX greatly sensitized human non-small-cell lung cancer A549 cells to radiation. In the xenograft tumor model, the combination of psm-PTX and radiation significantly delayed the tumor growth. These results demonstrated the feasibility of psm-PTX to enhance the chemoradiotherapeutic efficacy

Immunocytes as a Biocarrier to Delivery Therapeutic and Imaging Contrast Agents to Tumors

Radiotherapy for cancer treatment has been used for primary or adjuvant treatment in many types of cancer, and approximately half of all cancer patients are undergoing radiation. However, ionizing radiation exposure induces genetic alterations in cancer cells and results in recruitment of monocytes/macrophages by triggering signals released from these cells. Using this characteristic of monocytes/macrophages, we have attempted to develop a biocarrier loading radiosensitizing anticancer agents that can lead to enhance the therapeutic effect of radiation in cancer treatment. The aim of this study is to demonstrate the proof of this concept. THP-1 labeled with Qdot 800 or iron oxide (IO) effectively migrated into tumors of subcutaneous mouse model and increased recruitment after ionizing radiation. Functionalized liposomes carrying a radiosensitizing anticancer agent, doxorubicin, are successfully loaded in THP-1 (THP-1-LP-Dox) with reduced cytotoxicity, and THP-1-LP-Dox also was observed in tumors after intravenous administration. Here, we report that monocytes/macrophages as a biocarrier can be used as a selective tool for amplification of the therapeutic effects on radiotherapy for human cancer treatment

Local Mesenchymal Stem/Progenitor Cells Are a Preferential Target for Initiation of Adult Soft Tissue Sarcomas Associated with p53 and Rb Deficiency

The cell of origin and pathogenesis of the majority of adult soft tissue sarcomas (STS) remains poorly understood. Because mutations in both the P53 and RB tumor suppressor genes are frequent in STS in humans, we inactivated these genes by Cre-loxP–mediated recombination in mice with floxed p53 and Rb. Ninety-three percent of mice developed spindle cell/pleomorphic sarcomas after a single subcutaneous injection of adenovirus carrying Cre-recombinase. Similar to human STS, these sarcomas overexpress Cxcr4, which contributes to their invasive properties. Using irradiation chimeras generated by transplanting bone marrow cells from mice carrying either the Rosa26StoploxPLacZ or the Z/EG reporter, as well as the floxed p53 and Rb genes, into irradiated p53loxP/loxPRbloxP/loxP mice, it was determined that sarcomas do not originate from bone marrow–derived cells, such as macrophages, but arise from the local resident cells. At the same time, dermal mesenchymal stem cells isolated by strict plastic adherence and low levels of Sca-1 expression (Sca-1low, CD31negCD45neg) have shown enhanced potential for malignant transformation according to soft agar, invasion, and tumorigenicity assays, after the conditional inactivation of both p53 and Rb. Sarcomas formed after transplantation of these cells have features typical for undifferentiated high-grade pleomorphic sarcomas. Taken together, our studies indicate that local Sca-1low dermal mesenchymal stem/progenitor cells are preferential targets for malignant transformation associated with deficiencies in both p53 and Rb