[The effect of transforming growth factor ß(1) in the transition of bone marrow-derived macrophages into myofibroblasts during renal fibrosis].

To study which subgroup of bone marrow derived cells formed myofibroblasts and the mechanism that transforming growth factor ß(1)(TGFß(1)) regulates the formation of bone marrow derived macrophages into myofibroblasts during renal fibrosis. Chimeric mice were generated by lethally irradiation of C57 mice followed by transfusion of green fluorescent protein (GFP) labeled bone marrow cells. Complete marrow reconstitution was developed until 12 weeks after transplantation. The mice were randomly divided into Sham operation group, unilateral ureteral obstruction (UUO) 3 days group, UUO5 days group, UUO7 days group and UUO7 with TGFß(1) treatment group. Each group had four mice. Flow cytometry was used to evaluate cell components. Compared with Sham operation group the proportions of GFP(+) CD(14)(+)α-smooth muscle actin(α-SMA)(+) cells, GFP+ CD(44)(+)CD(105)(+)α-SMA(+) cells and GFP(+) F4/80(+) α-SMA(+) cells in each UUO group were progressively increased and the transformation rate in UUO7 day group was the highest. The GFP(+) F4/80(+) α-SMA(+) cells accounted for the largest population. TGFß(1) promoted the transformation of bone marrow derived macrophages into myofibroblasts. Compared with Sham operation group or UUO7 day group, the proportion of GFP(+) F4/80(+) α-SMA(+) cells increased in UUO7 day TGFß(1) treatment group. Compared with Sham operation group (or UUO7 days group) the protein expressions of F4/80, α-SMA, Collagen Ⅰ increased in UUO7 with TGFß(1) group. Bone marrow derived macrophages are considered as the main type of myofibroblast precursors during the development of renal fibrosis. TGFß(1) regulates the transformation of bone marrow-derived macrophages into myofibroblasts. This process contributes to progressive renal fibrosis and deterioration of renal function.

Albumin acts like transforming growth factor ß1 in microbubble-based drug delivery.

Unlike lipid-shelled microbubbles (MBs), albumin-shelled microbubbles (MBs) have not been reported to be actively targeted to cells without the assistance of antibodies. Recent studies indicate that the albumin molecule is similar to transforming growth factor ß (TGF-ß) both structurally and functionally. The TGF-ß superfamily is important during early tumor outgrowth, with an elevated TGF-ß being tumor suppressive; at later stages, this switches to malignant conversion and progression, including breast cancer. TGF-ß receptors I and II play crucial roles in both the binding and endocytosis of albumin. However, until now, no specific albumin receptor has been found. On the basis of the above-mentioned information, we hypothesized that non-antibody-conjugated albumin-shelled MBs can be used to deliver drugs to breast cancer cells. We also studied the possible roles of TGF-ß1 and radiation force in the behavior of cells and albumin-shelled MBs. The results indicate that albumin-shelled MBs loaded with paclitaxel (PTX) induce breast cancer cell apoptosis without the specific targeting produced by an antibody. Applying either an acoustic radiation force or cavitation alone to cells with PTX-loaded albumin MBs increased the apoptosis rate to 23.2% and 26.3% (p < 0.05), respectively. We also found that albumin-shelled MBs can enter MDA-MB-231 breast cancer cells and remain there for at least 24 h, even in the presence of PTX loading. Confocal micrographs revealed that 70.5% of the breast cancer cells took up albumin-shelled MBs spontaneously after 1 d of incubation. Applying an acoustic radiation force further increased the percentage to 91.9% in our experiments. However, this process could be blocked by TGF-ß1, even with subsequent exposure to the radiation force. From these results, we conclude that TGF-ß1 receptors are involved in the endocytotic process by which albumin-shelled MBs enter breast cancer cells. The acoustic radiation force increases the contact rate between albumin-shelled MBs and tumor cells. Combining a radiation force and cavitation yields an apoptosis rate of 31.3%. This in vitro study found that non-antibody-conjugated albumin-shelled MBs provide a useful method of drug delivery. Further in vivo studies of the roles of albumin MBs and TGF-ß in different stages of cancer are necessary.

Endothelium-dependent epithelial-mesenchymal transition of tumor cells: exclusive roles of transforming growth factor ß1 and ß2.

BACKGROUND: Induction of epithelial-mesenchymal transition (EMT) is essential for the metastasis of tumor cells and maintaining their stemness. This study aimed to examine whether endothelial cells, which are most closely located to tumor cells in vivo, play a role in inducing EMT in tumor cells or not. METHODS: Concentrated culture medium of bovine aortic endothelial cells (BAECs) was applied to tumor cell lines (A549 and PANC-1) and epithelial cell line (NMuMg). Cadherin conversion, expressions of α-smooth muscle actin and ZO-1, actin fiber formation and cell migration were examined as hallmarks of the induction of EMT in these cell lines. Transforming growth factor ß (TGFß) antibodies were used to neutralize TGFß1, TGFß2 and TGFß3. Expression and release of TGFß proteins in BAECs as well as in porcine and human endothelial cells were assessed by Western blotting and ELISA, respectively. RESULTS: Conditioned medium of BAEC induced EMT in the examined cell lines. All endothelial cells from various species and locations expressed TGFß1 and TGFß2 proteins and much lower level of TGFß3 protein. Conditioned medium from these endothelial cells contained TGFß1 and TGFß2, but TGFß3 could not be detected. Neutralizing antibody against each of TGFß1 or TGFß2 did not reverse endothelium-dependent EMT, but simultaneous neutralization of both TGFß1 and TGFß2 completely abolished it. CONCLUSIONS: Endothelial cells may play a role in the induction and maintenance of EMT in tumor cells by constitutively releasing TGFß1 and TGFß2. GENERAL SIGNIFICANCE: The present results provide a novel strategy of the inhibition of tumor metastasis by targeting vascular endothelium.