Effect of thalidomide on colorectal cancer liver metastases in CBA mice

Intraperitoneal injection of thalidomide alleviates early osteoarthritis development by suppressing vascular endothelial growth factor expression in mice

Vascular endothelial growth factor (VEGF) is expressed in articular cartilage and increases in expression levels have been associated with the progression of osteoarthritis (OA). Thalidomide is a drug that has been reported to inhibit angiogenesis and reduce VEGF production by downregulating VEGF expression. The objective of the present study was to determine whether intraperitoneal administration of thalidomide may attenuate early OA development in mice. Male C57BL/6 mice (10‑weeks‑old) were randomly assigned into the destabilization of the medial meniscus (Dmm) with thalidomide treatment (Dmm+Th), Dmm and Sham groups equally. An OA model was induced surgically in Dmm+Th and Dmm groups, and mice of the Dmm+Th group were subsequently treated with an intraperitoneal injection of thalidomide (200 mg/kg/day). At 2 and 4 weeks following surgery, the pathological alterations in cartilage samples were assessed qualitatively by hematoxylin and eosin staining and Safranin O/Fast green staining, and quantitatively by the Osteoarthritis Research Society International scoring system. The mRNA expression levels of matrix metalloproteinase‑13 (MMP‑13) and VEGF were measured by reverse transcription‑quantitative polymerase chain reaction. The protein expression levels of MMP‑13 and VEGF were detected by immunofluorescence and immunohistochemistry, respectively. The production of VEGF in serum was evaluated via an ELISA assay. Pathological scores were significantly higher in the Dmm and the Dmm+Th groups than those in the Sham group; however, the Dmm+Th group exhibited markedly less severe pathological changes compared with the Dmm group. Compared with the Sham group, the mRNA and protein expression levels of VEGF and MMP‑13 in the Dmm and the Dmm+Th groups were significantly increased. The Dmm+Th group exhibited significantly decreased expression levels of VEGF and MMP‑13, as well as significantly decreased serum VEGF concentration compared with the Dmm group. Thus, the results of the present study demonstrated that intraperitoneal administration of thalidomide may alleviate the development of early OA by suppressing VEGF expression in mice and may have potential as a novel therapy for the treatment of OA.

Styrene maleic acid copolymer-pirarubicin induces tumor-selective oxidative stress and decreases tumor hypoxia as possible treatment of colorectal cancer liver metastases

BACKGROUND

Pirarubicin, a derivative of doxorubicin, induces tumor destruction via the production of reactive oxygen species (ROS) but is associated with cardiotoxicity. As a macromolecule (conjugated to styrene-maleic acid [SMA]), SMA-pirarubicin is selective to tumors resulting in improved survival with decreased systemic toxicity. Tumor destruction is, however incomplete, and resistant cells at the periphery of the tumor contribute to recurrence. Tumor hypoxia is a major factor in tumor resistance. Understanding the effect of oxidative stress induced by SMA-pirarubicin on the tumor microenvironment may be key to overcoming resistance. This study investigated the pattern of ROS production and tumor hypoxia after treatment with SMA-pirarubicin in a murine model of colorectal liver metastases.

METHODS

Liver metastases were induced in male, CBA mice using a murine-derived colon cancer cell line. SMA-pirarubicin (maximum tolerated dose, 100 mg/kg) or pirarubicin, (maximum tolerated dose, 10 mg/kg) were administered intravenously 14 days after tumor induction. Systemic oxidative stress in serum, liver, and cardiac tissue was quantified using the thiobarbituric acid reactive substances assay. Flow cytometry and fluorescence microscopy were used to assess ROS production for 48 hours after treatment. Tumor hypoxia was quantified using immunohistochemistry for pimonidazole adducts.

RESULTS

SMA-pirarubicin (100 mg/kg) induced ROS exclusively in tumors with minimal levels in serum and cardiac tissue. ROS levels were induced in a time-dependent and dose-dependent manner optimal between 4 and 24 hours after drug administration. Although tumor hypoxia was decreased overall, residual tumor cells adjacent to patent vessels were hypoxic.

CONCLUSION

This study provides insight into the tumor microenvironment after chemotherapy. SMA-pirarubicin inhibits the growth of colorectal liver metastases by inducing ROS, which seems to be largely tumor selective. The temporal pattern of ROS production can be used to improve future dosing regimens. Furthermore, the observation that residual tumor cells are hypoxic clarifies the need for a multimodal approach with agents that can alter the hypoxic state to effect complete tumor destruction.

Long-term treatment of thalidomide ameliorates amyloid-like pathology through inhibition of β-secretase in a mouse model of Alzheimer's disease

Thalidomide is a tumor necrosis factor alpha (TNFα) inhibitor which has been found to have abilities against tumor growth, angiogenesis and inflammation. Recently, it has been applied in clinic for the treatment of multiple myeloma as well as some inflammatory diseases. However, whether thalidomide has any therapeutic effects on neurodegenerative disorders, i.e. Alzheimer’s disease (AD) is not clear. AD is characterized by excessive amount of amyloid β peptides (Aβ), which results in a significant release of inflammatory factors, including TNFα in the brain. Studies have shown that inhibition of TNFα reduces amyloid-associated pathology, prevents neuron loss and improves cognition. Our recent report showed that genetic inhibition of TNFα/TNF receptor signal transduction down-regulates β amyloid cleavage enzyme 1 (BACE1) activity, reduces Aβ generation and improves learning and memory deficits. However, the mechanism of thalidomide involving in the mitigation of AD neuropathological features remains unclear. Here, we chronically administrated thalidomide on human APPswedish mutation transgenic (APP23) mice from 9 months old (an onset of Aβ deposits and early stage of AD-like changes) to 12 months old. We found that, in addition of dramatic decrease in the activation of both astrocytes and microglia, thalidomide significantly reduces Aβ load and plaque formation. Furthermore, we found a significant decrease in BACE1 level and activity with long-term thalidomide application. Interestingly, these findings cannot be observed in the brains of 12-month-old APP23 mice with short-term treatment of thalidomide (3 days). These results suggest that chronic thalidomide administration is an alternative approach for AD prevention and therapeutics.

In vitro and in vivo evaluation of tumor targeting styrene-maleic acid copolymer-pirarubicin micelles: Survival improvement and inhibition of liver metastases

Pirarubicin is a derivative of doxorubicin with improved intracellular uptake and reduced cardiotoxicity. We have prepared a micellar formulation of pirarubicin using styrene-maleic acid copolymer (SMA) of mean molecular weight of 1.2 kDa, which exhibits a mean diameter of 248 nm in solution. Being a macromolecule, SMA-pirarubicin micelles exhibit excellent tumor targeting capacity due to the enhanced permeability and retention (EPR) effect. Here we report the antitumor activity of SMA-pirarubicin micelles on human colon and breast cancer cell lines in vitro, and a murine liver metastasis model in vivo. Metastatic tumor microvasculature, necrosis, apoptosis, proliferation, and survival were also investigated using immunohistochemistry for Ki-67, active caspase-3, and CD34, respectively. Drug cytotoxicity in vitro was assessed using MTT (3-[4,5-dimethyl-2-thiazolyl]-2, 5-diphenyl-2H-tetrazolium bromide) assay. In vivo, SMA-pirarubicin was administered at 100, 150, or 200 mg/kg (pirarubicin equivalent). Tumor microvasculature was also assessed using scanning electron microscopy. Styrene-maleic acid copolymer (SMA)-pirarubicin micelles were toxic against human colorectal and breast cancer cells in vitro. IC(50) was at or below 1 muM, free pirarubicin equivalent. In vivo, SMA-pirarubicin at 100 mg/kg reduced tumor volume by 80% and achieved a survival rate of 93% at 40 days after tumor inoculation. Styrene-maleic acid copolymer (SMA)-pirarubicin micelles demonstrated potent antitumor activity in this liver metastases model, contributing to prolonged survival. Histological examination of tumor nodules showed significant reduction and proliferation of tumor cells (>90%). The present results suggest that investigation of the effect of multiple dosing at later time points to further improve survival is warranted.

The antiangiogenic effect of thalidomide on occult liver metastases: an in vivo study in mice

AIM

To investigate the morphological changes of intratumoral microvessels after administration of thalidomide in occult hepatic metastases.

METHODS

Twenty mice with hepatic metastases created by injection of colon-26 tumor cells into the spleen were enrolled. Ten mice were treated with thalidomide (200 mg/kg) by intraperitoneal injection daily from the first day after inoculation of tumor cells, and the other 10 with saline only. Fifteen days after tumor cell inoculation, the intratumoral microvessels of hepatic metastases in both groups were studied by intravital microscopy and immunohistochemistry.

RESULTS

For the control group, although the intratumoral microvessel density (MVD) and CD34 positive microvessel density (MVD-CD34) of larger metastases (> 400 microm in diameter) were more than those of small metastases respectively (P < 0.01), the intratumoral branch density (BD) was similar to that of small metastases (P > 0.05). For the thalidomide treated group, despite the fact that MVD-CD34 of larger metastases was more than that of small metastases (P < 0.01), the MVD and BD were similar to those of small metastases respectively (P > 0.05). The MVD, BD and MVD-CD34 of small metastases of both groups were similar (P > 0.05); however, those of large metastases in the thalidomide treated group were significantly lower than those in the control group (P < 0.01).

CONCLUSIONS

Thalidomide exerts an antiangiogenic effect on occult hepatic metastases with angiogenesis only, and the different vascular components in the tumor vasculature demonstrate various responses to antiangiogenic therapy.

Customizing the targeting of IGF-1 receptor

The type 1 IGF receptor (IGF-IR) is activated by two ligands, IGF-1 and IGF-2, and by insulin at supraphysiological concentrations. It plays a significant role in the growth of normal and abnormal cells, and antibodies against the IGF-IR are now in clinical trials. Targeting of the IGF-IR in cancer cells (by antibodies or other means) can be improved by the appropriate selection of responsive tumors. This review focuses on the optimization of IGF-IR targeting in human cancer.

Magnetic resonance imaging for monitoring the effects of thalidomide on experimental human breast cancers

Thalidomide, which inhibits angiogenesis in certain tumor types, reduced extravasation of a macromolecular contrast medium (MMCM) in a human breast cancer model as assayed by MMCM-enhanced dynamic magnetic resonance imaging (MRI) and fluorescence microscopy in the same tumors. After a 1-week, three-dose course of thalidomide, the mean MRI-assayed endothelial transfer coefficient, K(PS), decreased significantly (p < 0.05) from 19.4 +/- 9.1 to 6.3 +/- 9.1 microl/min.100 cm(3). Correspondingly, microscopic measurements of extravasated MMCM, expressed as fractional area of streptavidin staining, were significantly (p < 0.05) lower in thalidomide-treated tumors (18.6 +/- 11.9%) than in control saline-treated tumors (50.2 +/- 2.3%). On a tumor-by-tumor basis, post-treatment K(PS) values correlated significantly (r(2) = 0.55, p < 0.05) with microscopic measures of MMCM extravasation. However, no significant differences were observed between saline- and thalidomide-treated tumors with respect to rate of growth, vascular richness, or amount of VEGF-containing cells. Because of its sensitivity to the detection of changes in vascular leakage in tumors, this MMCM-enhanced MRI assay could prove useful for monitoring the effects of thalidomide on an individual patient basis. The significant correlation between MRI and fluorescence microscopic measures of MMCM extravasation supports the utility of the non-invasive MRI approach for assessing the action of thalidomide on tumor blood vessels.

Inhibition of plaque neovascularization and intimal hyperplasia by specific targeting vascular endothelial growth factor with bevacizumab-eluting stent: An experimental study

Neovascularization is associated with destabilization of atheromatic plaques. Increased expression of vascular endothelial growth factor (VEGF) is important in the process of neovascularization. We assessed the effect of bevacizumab, a monoclonal antibody specific for VEGF, on neovascularization. We used 12 New Zealand rabbits under atherogenic diet for 3 weeks. We immersed a phosphorycholine coated stent into a solution of 4 ml bevacizumab according to previous studies. Twelve eluting stents and 12 non-eluting stents were implanted in the middle segment of the rabbit's iliac arteries. Follow-up angiography was performed at 4 weeks and tissues were obtained for histological analysis. The procedure of stent loading with bevacizumab and stent implantation was successful. There was no difference in angiographic measurements before, after implantation and at follow-up between the two groups. mean neointimal thickness (0.09+/-0.02 versus 0.12+/-0.02 mm, p<0.01), and mean neointimal area (1.08+/-0.09 versus 1.20+/-0.12 mm(2), p<0.01) were less in the bevacizumab treated segments. bevacizumab-treated arterial segments demonstrated significantly decreased microvessel density compared with the control group (1.69+/-0.06 CI: 1.65-1.73 versus 15.68+/-0.56 CI: 15.32-16.04 vessels per mm(2), p<0.001) and vegf expression was decreased in the media and adventitia of bevacizumab group. Endothelialization, inflammation and injury scores were similar between the two groups. These results suggest that bevacizumab-eluting stent implantation in rabbit iliac arteries is safe, and inhibits neovascularization without affecting the endothelialization.