pH-Responsive DNA nanoassembly for detection and combined therapy of tumor.

We have developed a novel cancer theragnostic nanoassembly with high biocompatibility, stability and low toxicity which are activated rapidly by tumor microenvironment to realize selective fluorescence imaging, chemotherapy as well as chemoenzymatic therapy. The nanoprobes are synthesized by hybridization of fluorophore labeled hairpin DNAs containing a 5-aza-dC at hemimethylated CpG sites and pH-sensitive DNA sequence covalently conjugated with PEGylated GO. The aptamer, which is also covalently conjugated on PEGylated GO, enables to target the tumor site and the weak acid environment of tumor triggers the release of drug loaded by nanoprobes including functionalized DNA and DOXs, effectively activating fluorescence signals and selectively killing the tumor cells. The results revealed that the nanoprobe enables sensitive detection of pH changes within subcellular environment, selectively imaging and great synergy of multicombination therapeutic including chemotherapy and chemoenzymatic therapy, implying that developed pH activatable probe has considerable potential for diagnosis and efficient therapy of cancer.

Side population cells isolated from KATO III human gastric cancer cell line have cancer stem cell-like characteristics.

AIM: To investigate whether the side population (SP) cells possess cancer stem cell-like characteristics in vitro and the role of SP cells in tumorigenic process in gastric cancer. METHODS: We analyzed the presence of SP cells in different human gastric carcinoma cell lines, and then isolated and identified the SP cells from the KATO III human gastric cancer cell line by flow cytometry. The clonogenic ability and self-renewal were evaluated by clone and sphere formation assays. The related genes were determined by reverse transcription polymerase chain reaction. To compare tumorigenic ability, SP and non-side population (NSP) cells from the KATO III human gastric cancer cell line were subcutaneously injected into nude mice. RESULTS: SP cells from the total population accounted for 0.57% in KATO III, 1.04% in Hs-746T, and 0.02% in AGS (CRL-1739). SP cells could grow clonally and have self-renewal capability in conditioned media. The expression of ABCG2, MDRI, Bmi-1 and Oct-4 was different between SP and NSP cells. However, there was no apparent difference between SP and NSP cells when they were injected into nude mice. CONCLUSION: SP cells have some cancer stem cell-like characteristics in vitro and can be used for studying the tumorigenic process in gastric cancer.

Side population cells from HXO-Rb44 retinoblastoma cell line have cancer-initiating property.

AIM: To ascertain whether side population (SP) cells in HXO-Rb44 retinoblastoma cell line have cancer stem cell-like property in vitro and in vivo. METHODS: We analyzed and sorted SP from HXO-Rb44 retinoblastoma cell line by Hoechst 33342 staining on flow cytometry. SP and NSP cells were determined their ability of proliferation and self-renewal by SP reanalysis, soft agar assay and tumor sphere assay in vitro. Clone formation was detected by seeding HXO-Rb44 and HXO-Rb44 -RFP cells into soft agar. The expression of ABCG2, MDRI, Bmi-1 and Oct-4 was determined by RT-PCR between SP and non-SP (NSP) cells. Moreover, they were injected into nude mice to determine their tumorigency in vivo. RESULTS: SP from HXO-Rb44 retinoblastoma cell line could grow clonally in soft agar assays and form tumor spheres from single cells in conditioned media. The expressions of ABCG2, MDRI, Bmi-1 and Oct-4 were significantly higher in SP than NSP cells. As few as SP cells resulted in tumor formation in 6 of 12 injected sites, however, the injection of NSP cells failed to form new tumor. CONCLUSION: SP cells isolated by Hoechst 33342 from the HXO-Rb44 retinoblastoma cell line had property of high tumorigency in vivo and in vitro. Therefore, SP might be a target while developing retinoblastoma therapies.

Identification of side population cells from bladder cancer cells by DyeCycle Violet staining.

Side population (SP) cells can be used to identify putative cancer stem cells (CSC), but this technique is hampered by the requirement for an ultraviolet (UV) laser source. DyeCycle Violet reagent (DCV) is a DNA-binding dye that can be used in the common violet laser diode (VLD)-equipped flow cytometer. In this paper, we analyzed SP cells from several bladder cancer cell lines using either Hoechst 33342 or DCV staining. The Hoechst 33342-stained SP cells were identified with a UV-equipped flow cytometer, while the DCV-stained SP cells were identified with a VLD-equipped flow cytometer. DCV staining was also used to sort SP and non-SP (NSP) cells from SW780 cells. Further analysis revealed that SP cells could give rise to both SP and NSP cells. The colony-forming ability of SP cells was significant greater than that of NSP cells. When injected into nude mice, as few as 1 x 10(3) SP cells could initiate tumors in eight of twelve injection sites. In contrast, the injection of NSP cells into nude mice failed to initiate tumors. RT-PCR data showed that the expression of ABCG2, MDRI, Bmi-1 and Oct-4 differed between SP and NSP cells, suggesting that SP cells possess some stem cell characteristics. We conclude that SP cells identified by DCV staining are capable of asymmetric division, self-renewal and tumor initiation. Our study also indicates that DCV is a useful reagent for the identification of SP cells.