Rapamycin Liposomes Combined with 5-Fluorouracil Inhibits Angiogenesis and Tumor Growth of APC (Min/+) Mice and AOM/DSS-Induced Colorectal Cancer Mice

BACKGROUND

Transgenic C57BL/6-APC^(Min/+) spontaneous cancer mouse model and the Azoxymethane (AOM)/Dextran Sulfate Sodium (DSS) chemically induced orthotopic colorectal cancer mouse model represented distinct pathogenesis of colorectal cancers. Our previous study revealed that the combination of Rapamycin liposomes (Rapa/Lps) and 5-Fluorouracil (5-FU) has anti-colorectal cancer effects. However, the therapeutic efficacy of Rapa/Lps and 5-FU in other colorectal cancer mice models is yet to be thoroughly explored. The purpose of this study was to investigate the anti-tumor effect of Rapa/Lps combined with 5-FU in vivo and in vitro.

METHODS

In this study, we evaluated the effect of Rapa/Lps and 5-FU on APC ^(Min/+) mice and AOM/DSS-induced colorectal cancer mice. The small intestine, colorectum, serum, and plasma of mice in each group were collected following sacrifice to record the number of tumors. HE staining was utilized for observing pathological damage to intestine tissues. Tube formation assay, Transwell assay, wound healing assay, Western Blot were used to explore the anti-angiogenesis effect of drugs in HUVECs.

RESULTS

As expected, Rapa/Lps and 5-FU significantly suppressed tumor formation, decreased the number of tumors, and tumor load both in two mouse models, and had no influence on mouse weight. Mechanically, the anti-tumor effect of the drug also was associated in inhibiting angiogenesis and proliferation. Furthermore, we found that Rapa/Lps obviously inhibited HUVECs tube formation and migration.

CONCLUSION

Altogether, we revealed the Rapa/Lps synergism with 5-FU decreased colon and small intestinal tumorigenesis in AOM/DSS-treated and APC ^(Min/+) mice, respectively, and correlated with anti-angiogenesis.

Delivery of Rapamycin by Liposomes Synergistically Enhances the Chemotherapy Effect of 5-Fluorouracil on Colorectal Cancer

Background

Rapamycin is a promising agent for treating tumors, but clinical applications of rapamycin are limited due to its poor water solubility and low bioavailability. This paper constructs a liposome delivery system for rapamycin to improve the effect in treating colorectal cancer.

Methods

We prepared the rapamycin liposomes using the ethanol injection method. The cellular uptake and biodistribution were detected by LC-MS and in vivo imaging system. MTT assay, transwell migration experiment, flow cytometry, and Western blot analysis evaluated the antitumor effect of rapamycin liposomes in vitro. Furthermore, HCT-116 tumor-bearing mice were used to assess the therapeutic efficacy of rapamycin liposomes in vivo.

Results

The prepared rapamycin liposomes had a particle size of 100±5.5 nm and with a narrow size distribution. In vitro cellular uptake experiments showed that the uptake of rapamycin liposomes by colorectal cells was higher than that of free rapamycin. Subsequently, in vivo imaging experiments also demonstrated that rapamycin liposomes exhibited higher tumor accumulation. Therefore, the ability of rapamycin liposomes to inhibit tumor proliferation, migration and to induce tumor apoptosis is superior to that of free rapamycin. We also demonstrated in vivo good antitumor efficacy of the rapamycin liposomes in HCT-116 xenograft mice. In addition, rapamycin liposomes and 5-FU can synergistically improve the efficacy of colorectal cancer via the Akt/mTOR and P53 pathways.

Conclusion

Collectively, rapamycin liposomes are a potential treatment for colorectal cancer, as it not only improves rapamycin’s antitumor effect but also synergistically enhances 5-FU’s chemotherapy effect.

Myrothecol A, a new alkylresorcinol with cytotoxicity from Myrothecium sp

A new alkylresorcinol, myrothecol A (1), along with two known ones (2 and 3), were isolated from a fungal strain Myrothecium sp. GY170016. Their structures were elucidated by extensive spectroscopic analysis. The absolute configuration of 1 was determined by electronic circular dichroism experiment. This is the first case of the presence of alkylresorcinols in genus Myrothecium. All the isolates were evaluated for their cytotoxic activities against human cancer cell line MCF-7 with IC₅₀ values of 16.7, 13.2, 21.3 μM, respectively.

Curcumin inhibits cellular cholesterol accumulation by regulating SREBP-1/caveolin-1 signaling pathway in vascular smooth muscle cells

AIM

To investigate the protective effect and the possible mechanism of curcumin on anti-atherosclerosis.

METHODS

Morphological changes of atherosclerotic lesions taken from apoE knockout (apoE-/-) mice were determined by hematoxylin- eosin staining. Intracellular lipid droplets and lipid levels were assayed by oil red O staining and HPLC. The protein expression of caveolin-1 was quantified by Western blotting. Translocation and the expression of sterol response element-binding protein-1 (SREBP-1) were indirectly detected by an immunofluorescence analysis.

RESULTS

The administration of 20 mg. kg(-1 ). d(-1 )curcumin to apoE-/- mice for 4 months induced a 50% reduction of atherosclerotic lesions and yielded a 5- fold increase in the caveolin-1 expression level as compared to the model group. Rat vascular smooth muscle cells (VSMC) pretreated with 50 mg/L ox-lipid density lipoprotein(ox-LDL) for 48 h increased cellular lipid contents, and stimulated SREBP-1 translocation, but decreased the caveolin-1 expression level. Lipid-loaded cells exposed to curcumin at various concentrations (12.5, 25, and 50 micromol/L) for different durations (0, 6, 12, 24, and 48 h) significantly diminished the number and area of cellular lipid droplets, total cholesterol, cholesterol ester, and free cholesterol accompanying the elevation of the caveolin-1 expression level (approximately 3-fold); the translocation of SREBP-1 from the cytoplasm to the nucleus was inhibited compared with the models. Lipid-loaded VSMC exposed to N-acetyl- Leu-Leu-norleucinal, a SREBP-1 protease inhibitor, showed increased nuclear translocation of SREBP-1, reduced caveolin-1 expression level, and upregulated cellular lipid levels.

CONCLUSION

Curcumin inhibits ox-LDL-induced cholesterol accumulation in cultured VSMC through increasing the caveolin-1 expression via the inhibition of nuclear translocation of SREBP-1.

[Preparation and identification of monoclonal antibody against human thrombomodulin.]

To produce specific monoclonal antibody (McAb) against human thrombomodulin (hTM), the full-length hTM cDNA-expressing plasmid pThr402 was transfected into CHO cells by Lipofectamine 2000 reagent. The hTM-expressing CHO cells, which was confirmed by flow cytometry and Western blot, were obtained by G418 selection. Then the McAb against hTM was prepared with classic hybridoma technique. A cell line of CHO-TM5 with high level of hTM was used to immunize female Balb/c mice 3 times at an interval of 4 weeks. On the third day after the third immunization, mice were sacrificed and spleen cells were harvested to prepare hybridoma cells with SP2/0 cells at the ratio of 10 to 1. Hybridoma cells were then cultured at 96-well plates for screening. Cellular enzyme-linked immunoabsorbent assay (CELISA) was applied twice. The first CELISA was done with polythene ELISA plate with a monolayer of CHO-TM5 cells. The positive clones from the first screen were then selected by reacting with similar screening ELISA plate but with CHO cell monolayer instead. Only clones that were positive for the first screening and negative for the second screening were kept, and called as CHO-TM5(+)CHO(-) hybridoma cells. Balb/c mice were intraperitoneally injected with the selected hybridoma cells. Ascites were collected and monoclonal antibodies were purified using FPLC, and its Ig class, subclass, and titer were then determined respectively. The specificity of the yielded McAb was identified with CELISA, flow cytometry, ABC immunohistochemistry and immunoblotting. One line of hybridoma cells with high expression of specific McAb against hTM, NH-1, was obtained. The Ig subclass of the McAb was IgG1 and the titer of ascitic McAb was 1x10(-6). Flow cytometry, CELISA and Western blot assays demonstrated that McAb NH-1 could specifically recognize hTM expressed in CHO-TM5 cells and human umbilical vascular endothelial cells. Meanwhile, the tissue specificity of antigen recognized by McAb NH-1 was identified by immunohistochemical ABC staining. NH-1 can specifically recognize the natural hTM expressed mainly in vascular endothelial cells, which will potentially be useful for investigation of the functions and clinic values of hTM.

Effect of Caveolin-1 on growth of human gastric cancer cell Line MGC803

AIM: To investigate the effect of Caveolin-1 on the proliferation and differentiation of gastric carcinoma cell line MGC803, and explore the probability that Caveolin-1 can be used for gene therapy.

METHODS: Caveolin-1 gene and Pcl-neo control plasmid were transfected into human MGC803 cell line by lipofectin, respectively. The positive clones were selected by G418. We also stabled a positive control group which was treated with PD98059 for 48 hours. Then the expression of Caveolin-1 in each group was detected by Western blot. Cell morphology was observed under optical microscope. Cell population doubling time was determined by cell counting method and cell cycle was analyzed by flow cytometry.

RESULTS: The expression of Caveolin-1 was significantly higher in the cells treated with Caveolin-1 or PD98059 than that in the empty controls (P < 0.001, q = 23.067 or 13.3376). Furthermore, Caveolin-1 expression was also markedly higher in the cells transfected with Caveolin-1 than that in the positive controls (P < 0.001, q = 9.7294). Under light microscope, marked changes occurred in cell morphous after gene transfection. Before transfection, the cells had a significant heteromorphism, with the features of large cell body, little cytoplasm, obvious karyokinesis. While in Caveolin-1-transfected MGC803 cells, the cell malignancy declined as the cellular heteromorphism diminished, with the ratio of nuclear-to-cytoplasm decreased, and the karyokinesis disappeared. Caveolin-1-transfected cells had an extended doubling time (65.46 h vs 46.67 h, P < 0.05, q = 4.8695). At same time, the population of Caveolin-1-transfected cells in G₀/G₁ phase was obviously increased (P < 0.01, q = 9.1824) while that in S phase was decreased (P < 0.01, q = 7.827). There were also notable differences in cell cycle distribution between Caveolin-1-transfected cells and the positive controls (G₀/G₁: P < 0.01, q = 4.9323; S: P < 0.05, q = 3.3295).

CONCLUSION: Caveolin-1 not only induces the differentiation of MGC803 cells, but also blocks them at in G₀/G₁ phase. Caveolin-1 can inhibit the proliferation of MGC803 cells in vitro by prolonging the cell doubling time.

17beta-estradiol potentiates ischemia-reperfusion injury in diabetic ovariectomized female rats

To investigate the effect of 17beta-estradiol (E2) on ischemia-reperfusion (I/R) injury in diabetic ovariectomized female rats. Streptozotocin(STZ)-induced diabetic female rats received E2 treatment for 2 weeks after ovariectomy (OVX). A period of 90 min of temporary middle cerebral artery occlusion (tMCAO) was used for the study. Rats were evaluated for physiological data including plasma glucose, E2, MAP, PaCO2 and PaO2 before and after tMCAO. P-selectin expression, myeloperoxidase (MPO) enzyme activity and the cerebral infarct volume were analyzed.

RESULTS

The infarct volume in the E2-treated OVX rats is bigger than that in intact and OVX groups. However, there is not a significant different area of cerebral infarct between diabetic OVX and intact rats. Significant upregulation of P-selectin expression and MPO activity of the ischemia-reperfusion hemisphere were observed in E2 + OVX, intact and OVX groups at 8, 24, 72 h in time manner after tMCAO compared with that of the contralateral hemisphere of cerebral ischemia-reperfusion. Both P-selectin expression and MPO activity in the E2 + OVX and intact rats are significantly higher than that in the untreated OVX rats. Chronic estrogen replacement therapy (ERT) potentiates the I/R injury in diabetes female rats. This may be related to the increased expression of P-selectin and MPO activity.