Liposomes targeting the cancer cell-exposed receptor, claudin-4, for pancreatic cancer chemotherapy.

BACKGROUND: Claudin-4 (CLDN4), a tight junction protein, is overexpressed in several types of cancer, and is considered a biomarker for cancer-targeted treatment. CLDN4 is not exposed in normal cells, but becomes accessible in cancer cells, in which tight junctions are weakened. Notably, surface-exposed CLDN4 has recently been found to act as a receptor for Clostridium perfringens enterotoxin (CPE) and fragment of CPE (CPE17) that binds to the second domain of CLDN4. METHODS: Here, we sought to develop a CPE17-containing liposome that targets pancreatic cancers through binding to exposed CLDN4. RESULTS: Doxorubicin (Dox)-loaded, CPE17-conjugated liposomes (D@C-LPs) preferentially targeted CLDN4-expressing cell lines, as evidenced by greater uptake and cytotoxicity compared with CLDN4-negative cell lines, whereas uptake and cytotoxicity of Dox-loaded liposomes lacking CPE17 (D@LPs) was similar for both CLDN4-positive and negative cell lines. Notably, D@C-LPs showed greater accumulation in targeted pancreatic tumor tissues compared with normal pancreas tissue; in contrast, Dox-loaded liposomes lacking CPE17 (D@LPs) showed little accumulation in pancreatic tumor tissues. Consistent with this, D@C-LPs showed greater anticancer efficacy compared with other liposome formulations and significantly extended survival. CONCLUSIONS: We expect our findings will aid in the prevention and treatment of pancreatic cancer and provide a framework for identifying cancer-specific strategies that target exposed receptors.

Dual Effect of Chemo-PDT with Tumor Targeting Nanoparticles Containing iRGD Peptide.

Nanotechnology, including self-aggregated nanoparticles, has shown high effectiveness in the treatment of solid tumors. To overcome the limitations of conventional cancer therapies and promote therapeutic efficacy, a combination of PDT and chemotherapy can be considered an effective strategy for cancer treatment. This study presents the development of tumor-targeting polysialic acid (PSA) nanoparticles for chemo-PDT to increase the cellular uptake and cytotoxic effect in cancer cells. Chlorin e6 (Ce6), a photosensitizer, and the iRGD peptide (sequence; cCRGDKGPDC) were conjugated to the amine of N-deacetylated PSA. They generate reactive oxygen species (ROS), especially singlet oxygen (1O2), and target integrin αvß3 on the cancer cell surface. To offer a chemotherapeutic effect, doxorubicin (Dox) was assembled into the core of hydrophobically modified PSA by connecting it with Ce6; this was followed by its sustained release from the nanoparticles. These nanoparticles are able to generate ROS under 633 nm visible-light irradiation, resulting in the strong cytotoxicity of Dox with anticancer effects in HCT116 cells. PSA nanoparticles with the dual effect of chemo-PDT improve conventional PDT, which has a poor ability to deliver photosensitizers to cancer cells. Using their combination with Dox chemotherapy, rapid removal of cancer cells can be expected.

Bakuchiol, main component of root bark of Ulmus davidiana var. japonica, inhibits TGF-ß-induced in vitro EMT and in vivo metastasis.

Cancer is a second leading cause of death worldwide, and metastasis is the major cause of cancer-related mortality. The epithelial-mesenchymal transition (EMT), known as phenotypic change from epithelial cells to mesenchymal cells, is a crucial biological process during development. However, inappropriate activation of EMT contributes to tumor progression and promoting metastasis; therefore, inhibiting EMT is considered a promising strategy for developing drugs that can treat or prevent cancer. In the present study, we investigated the anti-cancer effect of bakuchiol (BC), a main component of Ulmus davidiana var. japonica, in human cancer cells using A549, HT29 and MCF7 cells. In MTT and colony forming assay, BC exerted cytotoxicity activity against cancer cells and inhibited proliferation of these cells. Anti-metastatic effects by BC were further confirmed by observing decreased migration and invasion in TGF-ß-induced cancer cells after BC treatment. Furthermore, BC treatment resulted in increase of E-cadherin expression and decrease of Snail level in Western blotting and immunofluorescence analysis, supporting its anti-metastatic activity. In addition, BC inhibited lung metastasis of tail vein injected human cancer cells in animal model. These findings suggest that BC inhibits migration and invasion of cancers by suppressing EMT and in vivo metastasis, thereby may be a potential therapeutic agent for treating cancers.

Amentoflavone, active compound of Selaginella tamariscina, inhibits in vitro and in vivo TGF-ß-induced metastasis of human cancer cells.

Epithelial mesenchymal transition (EMT) is a well-known and important step in metastasis and thus can be a key target in cancer treatment. Here, we tested the EMT inhibitory actions of Selaginella tamariscina and its active component, amentoflavone (AF). EMT was examined in vitro using wound-healing and invasion assays and by monitoring changes in the expression of the EMT-related proteins, E-cadherin, Snail, and Twist. Metastasis was examined in vivo using SCID mice injected with luciferase-labeled A549 cells. We confirmed that aqueous extracts of S. tamariscina (STE) and AF inhibited EMT in human cancer cell lines. We found that STE and AF at nontoxic concentrations exerted remarkable inhibitory effects on migration (wound healing assay) and invasion (Transwell assay) in tumor necrosis factor (TGF)-ß-treated cancer cells. Western blotting and immunofluorescence imaging show that AF treatment also restored E-cadherin expression in these cells compared to cells treated with TGF-ß only. Suppression of metastasis by AF was investigated by monitoring migration of tail-vein-injected, circulating A549-luc cells to the lungs in mice. After 3 wk, fewer nodules were observed in mice co-treated with AF compared with those treated with TGF-ß only. Our findings indicate that STE and AF are promising EMT inhibitors and, ultimately, potentially potent antitumor agents.

Hypoxia-responsive folic acid conjugated glycol chitosan nanoparticle for enhanced tumor targeting treatment.

Hypoxia is a characteristic feature of various ischemic diseases, including cancer. This study describes the development of glycol chitosan nanoparticles, hydrophobically modified with 4-nitrobenzyl chloroformate and folic acid (FA), that can specifically release drugs under hypoxic conditions. This hypoxia-responsive glycol chitosan nanoparticle conjugated with FA (HRGF) possesses tumor-targeting properties by virtue of conjugated FA and is able to release drugs in a nitroreductase (NTR)-dependent manner because its structure is cleaved by NTR under hypoxic conditions. HRGF nanoparticles showed improved in vivo cancer-targeting ability compared with HRG nanoparticles without FA. In vitro drug release profiles revealed that doxorubicin (DOX)-loaded HRGF (D@HRGF) nanoparticles showed rapid release under hypoxia conditions than normoxic conditions. In vitro cytotoxicity tests and microscopic observations showed that D@HRGF nanoparticles were more toxic towards hypoxic cells than normoxic cells, and that the release of DOX was more effective in hypoxia than normoxia. In vivo, D@HRGF nanoparticles showed more effective antitumor activity in mice compared with D@HRG and free DOX. Collectively, these results show that HRGF nanoparticles function as an effective drug-delivery system in hypoxic conditions. Moreover, these hypoxia-responsive nanoparticles would be effective not only in cancer, but also in other ischemic diseases.