[Synthesis and characterization of folic acid-conjugated chitosan nanoparticles as a tumor-targeted drug carrier].

OBJECTIVE: To synthesize and characterize paclitaxel (PTX)-loaded folate-conjugated chitosan (FA-CTS/PTX) nanoparticles and evaluate its cytotoxicity in vitro. METHODS: CTS/PTX and FA-CTS/PTX nanoparticles were prepared using reductive amidation and ionic gelation of chitosan with tripolyphosphate anions (TPP). The particle size was determined by laser scattering and the morphology observed using transmission electron microscopy, and the PTX content in the nanoparticles was determined using ultraviolet spectrophotometer at 227 nm. The in vitro cytotoxicity of the nanoparticles against HeLa cells was evaluated by MTT assay. Fluorescence microscopy was used to observe the HeLa cells incubated with FA-chitosan nanoparticles in the presence or absence of folic acid in the culture medium. RESULTS: PTX loading did not cause adhesion of the FA-CTS nanoparticles, which presented with uniform spherical morphology with an average diameter of 282.8 nm. The loading and encapsulation efficiencies of FA-CTS/PTX were 9.0% and 75.4%, respectively. The FA-CTS nanoparticles showed a greater extent of intracellular uptake in the absence of folic acid, indicating that the cellular uptake of the nanoparticles occurred through endocytosis mediated by the folate receptors. The PTX-loaded FA-CTS nanoparticles exhibited potent cytotoxicity against HeLa cells, an effect 2- to 3-fold stronger than that of PTX-loaded CTS nanoparticles. CONCLUSION: FA-CTS can be a promising drug carrier with high efficiency in condensing drug, good tumor-targeting ability and low cytotoxicity.

[Correlation of antitumor drug sensitivity between marrow mesenchymal stem cells (MSCs) and hepatocarcinoma cells in rats].

BACKGROUND & OBJECTIVE: As hepatocarcinoma stem cells may originate from oval cells and oval cells are difficult to be separated and purified, MSCs (marrow mesenchymal stem cells), which are the progenitor cells of the hepatocarcinoma stem cells, were selected instead in our study to investigate the correlation of anticancer drug sensitivity between hepatocarcinoma cells and MSCs in rats. METHODS: The primary liver carcinoma modle of rats was induced by diethylnitrosamine. Tumor cells and MSCs from eight hepatocarcinoma rats were separated. The inhibitory effects of 3 anticancer drugs [adriacin (0.04 microg/ml), cisplatin (0.2 microg/ml) and fluorouracil (1 microg/ml)] to hepatocarcinoma cells and MSCs were measured by MTT assay. The weight of the tumor in nude mice which were injected with rat hepatocarcinoma cells was measured after 6 weeks. Then the correlation of the inhibitory ratio of 3 anticancer drugs to hepatocarcinoma cells and MSCs, and to the tumor weight of nude mice was analyzed. RESULTS: No correlation was revealed between the inhibitory ratio of 3 anticancer drugs to hepatocarcinoma cells and the tumor weights of nude mice injectal with drug treated tumor cells. The correlation coefficient was: 0.6307 (adriacin, P>0.05), 0.4358 (fuiorouracil, P>0.05) and 0.7080 (cisplatin, P>0.05). No correlation was observed between the inhibitory ratio of 3 anticancer drugs to hepatocarcinoma cells and to MSCs. The correlation coefficient was: 0.6316 (adriacin, P>0.05), 0.4214 (fluorouracil, P>0.05) and 0.5943 (cisplatin, P>0.05). However, significant reverse correlation was found between the inhibitory ratio of 3 anticancer drugs to MSCs and the tumor weights of nude mice injectal with drug treated tumor cells. The correlation coefficient was: -0.8308 (adriacin, P<0.05), -0.8991 (fluorouracil, P<0.01) and -0.8311 (cisplatin, P<0.05). CONCLUSIONS: Conventional anticancer drug sensitivity experiments could not reflect the chemoresistance of the hepatocarcinoma cells. However the inhibitory ratio of the anticancer drugs to MSCs in the hepatocarcinoma rats can reflect the chemoresistance of hepatocarcinoma cells accordingly.

[The biological behavior of hepatocarcinoma stem cells in rats].

OBJECTIVES: To study the biological behavior of hepatocarcinoma stem cells in rats. METHODS: Primary liver carcinomas were induced in rats using diethylnitrosamine. Tumor cells from 8 rats were separated according to rats oval cell (OVC) markers CD34, c-Kit, Thy-1, AFP, CK7, CK8, CK14, CK18, CK19 and GGT and then they were separately injected into the livers of nude mice. The tumors grown from the different subpopulation of OVC markers in the nude mice livers (10 OVC markers negative or positive cells) were weighted 1 month after the inoculations. The hepatocarcinoma cell subpopulations with higher ability in causing tumor growths were further studied in vitro. The cell cycles and DNA content of those subpopulation cells were investigated using flow cytometry. RESULTS: (1) Subpopulation cells with CK7(-), Thy-1(+) and AFP(+) markers had a higher ability in causing tumors in nude mice; (2) Subpopulation cells, exhibiting characters of TSC, had a low growth rate in vitro. CONCLUSIONS: (1) Different subpopulations of hepatocarcinoma cells had different abilities in causing tumors in rats. Some subpopulation cells, such as CK7(-), Thy-1(+) and AFP(+) cells, have characteristics of tumor stem cells. (2) The hepatocarcinoma stem cells may have a low growth rate in vitro.

[Expression of DNA transcription- and repair-related genes in cisplatin-resistant human ovarian carcinoma cell line COC1/DDP].

OBJECTIVE: To study the molecular mechanism underlying cisplatin resistance in ovarian carcinoma by detecting the expressions of DNA transcription- and repair-related genes in cisplatin-resistant human ovarian carcinoma COC1 cell line. METHODS: The differential expression of DNA transcription- and repair-related genes between the parental COC1 and cisplatin-resistant COC1/DDP cell line was determined using cDNA microarray. RESULTS AND CONCLUSION: Compared with COC1 cells, 143 genes in COC1/DDP cells showed significant differential expression, among which 20 were DNA transcription- and repair-related genes including 13 significantly up-regulated genes and 7 down-regulated ones. Abnormality of DNA transcription and repair might be involved in the development of cisplatin resistance in COC1/DDP cells.

Synthesis of targeted drug delivery system for fluorouracil using sulfadiazine as the carrier.

OBJECTIVE: To synthesize a targeted drug delivery system for 5-fluorouracil (5Fu) using sulfadiazine (SF) as a carrier with reduced side-effects and strong antitumor activity. METHODS: SF-poly (ethylene glycol) (PEG) conjugate was initially synthesized. 5Fu was subjected to reaction with trichloromethyl chloroformate to prepare chloroformyl 5Fu, which was linked to a spacer hydroxyl group of PEG that served as a macromolecular linking arm between SF and 5Fu. The content of 5Fu in the conjugate was determined by ultraviolet spectrophotometry. Spectrum of ultraviolet and infrared along with differential scanning calorimetry were employed to identify the structure of the conjugate of SFPEG-end capped 5Fu. RESULTS: The drug loading content of the conjugate was 3.2 %, and structural analysis confirmed the linkage between 5Fu and SF via PEG. CONCLUSION: Targeted drug delivery system for 5Fu using SF as a carrier has been successfully synthesized by this means.