Low-dose metronomic paclitaxel chemotherapy suppresses breast tumors and metastases in mice

This study investigated the use of low-dose metronomic (LDM) chemotherapy with paclitaxel in a highly metastatic mouse model of 4T1 breast cancers, and compared it with the maximum tolerable dose (MTD) therapy. LDM therapy displayed a stronger anti-tumor activity in suppressing primary and metastatic breast tumors with less degree of side effects, and stronger anti-angiogenic and anti-lymphangiogenic activities than MTD therapy. But MTD therapy showed stronger pro-apoptotic and anti-proliferative activities in situ. Paclitaxel therapy downregulated expression of vascular endothelial growth factor receptor-2 (VEGFR2) and up-regulated expression of thrombospondin-1. The results support the application of paclitaxel LDM therapy to treat advanced breast cancer.

Therapeutic effects of matrine on primary and metastatic breast cancer

Matrine, one of the main components extracted from a traditional Chinese herb, Sophora flavescens Ait, has displayed anti-cancer activity in several types of cancer cells. This study aims to evaluate the therapeutic benefits of matrine on primary and metastatic breast cancer. Matrine inhibited the viability of and induced apoptosis in human MCF-7 and mouse 4T1 breast cancer cells in a dose-dependent manner in vitro as shown by MTT assay, flow cytometry and laser scanning confocal microscopy. Administration of matrine inhibited the growth of primary tumors and their metastases to lungs and livers, in a dose-dependent manner, in a highly metastatic model of 4T1 breast cancer established in syngeneic Balb/c mice. Tumors from matrine-treated mice had a smaller proliferation index, shown by immunostaining with an anti-Ki-67 antibody, a greater apoptosis index, shown by TUNEL-staining, and a less microvessel density, shown by immunostaining with an anti-CD31 A antibody, compared to the controls. Western blot analysis of tumoral homogenates indicated that matrine therapy reduced the ratio of Bcl-2/Bax, downregulated the expressions of VEGF and VEGFR-2, and increased the activation of caspase-3 and caspase-9. This study suggests matrine may be a potent agent, from a natural resource, for treating metastatic breast cancer because of its anti-apoptotic, anti-proliferative and anti-angiogenic activities.

A comparative assessment of a-lipoic acid N-phenylamides as non-steroidal androgen receptor antagonists both on and off gold nanoparticles

A group of α-lipoic acid N-phenylamides were synthesized employing a variety of amide coupling protocols utilizing electron deficient anilines. These compounds were then assessed for their ability to block androgen-stimulated proliferation of a human prostate cancer cell line, LNCaP. These structurally simple compounds displayed anti-proliferative activities at, typically, 5–20 μM concentrations and were comparable to a commonly used anti-androgen Bicalutamide®. The inclusion of a disulfide (RS-SR) moiety, serving as an anchor to several metal nanoparticle systems (Au, Ag, Fe₂O₃, etc.), does not impede any biological activity. Conjugation of these compounds to a gold nanoparticle surface resulted in a high degree of cellular toxicity, attributed to the absence of a biocompatible group such as PEG within the organic scaffold.

Imprinted CDKN1C is a tumor suppressor in rhabdoid tumor and activated by restoration of SMARCB1 and histone deacetylase inhibitors

SMARCB1 is deleted in rhabdoid tumor, an aggressive paediatric malignancy affecting the kidney and CNS. We hypothesized that the oncogenic pathway in rhabdoid tumors involved epigenetic silencing of key cell cycle regulators as a consequence of altered chromatin-remodelling, attributable to loss of SMARCB1, and that this hypothesis if proven could provide a biological rationale for testing epigenetic therapies in this disease. We used an inducible expression system to show that the imprinted cell cycle inhibitor CDKN1C is a downstream target for SMARCB1 and is transcriptionally activated by increased histone H3 and H4 acetylation at the promoter. We also show that CDKN1C expression induces cell cycle arrest, CDKN1C knockdown with siRNA is associated with increased proliferation, and is able to compete against the anti-proliferative effect of restored SMARCB1 expression. The histone deacetylase inhibitor (HDACi), Romidepsin, specifically restored CDKN1C expression in rhabdoid tumor cells through promoter histone H3 and H4 acetylation, recapitulating the effect of SMARCB1 on CDKNIC allelic expression, and induced cell cycle arrest in G401 and STM91-01 rhabdoid tumor cell lines. CDKN1C expression was also shown to be generally absent in clinical specimens of rhabdoid tumor, however CDKN1A and CDKN1B expression persisted. Our observations suggest that maintenance of CDKN1C expression plays a critical role in preventing rhabdoid tumor growth. Significantly, we report for the first time, parallels between the molecular pathways of SMARCB1 restoration and Romidepsin treatment, and demonstrate a biological basis for the further exploration of histone deacetylase inhibitors as relevant therapeutic reagents in the treatment of rhabdoid tumor.

Doxycycline-inducible expression of SPARC/osteonectin/BM40 in MDA-MB-231 human breast cancer cells results in growth inhibition

SPARC (secreted protein acidic and rich in cysteine)/BM40/Osteonectin is a matricellular protein with multiple effects on cell behaviour. In vitro, its major known functions are anti-adhesive and anti-proliferative, and it is associated with tissue remodelling and cancer in vivo. SPARC is overexpressed in many cancers, including breast cancer, and the effects of SPARC seem to be cell type-specific. To study the effects of SPARC on breast cancer, we transfected SPARC into the MDA-MB-231 BAG, human breast cancer cell line using the Tet-On inducible system. By western analysis, we found low background levels in the MDA-MB-231 BAG and clone X parental cells, and prominent induction of SPARC protein expression after doxycycline treatment in SPARC transfected clones X5, X21, X24 and X75. Induction of SPARC expression did not affect cell morphology or adhesiveness to collagens type I and IV, but it slowed the rate of proliferation in adherent cultures. Cell cycle analysis showed that SPARC slowed the progression to S phase. Doxycycline induction of SPARC also slowed the rate of monolayer wound closure in the cultured wound healing assay. Thymidine inhibition of proliferation abrogated this effect, confirming that it was due to anti-proliferation rather than inhibition of migration. Consistent with this, we were unable to detect any differences in migration and Matrigel outgrowth analysis of doxycycline-stimulated cells. We conclude that SPARC is inhibitory to human breast cancer cell proliferation, and does not stimulate migration, in contrast to its stimulatory effects reported for melanoma (proliferation and migration) and glioma (migration) cells. Similar growth repression by SPARC has been reported for ovarian cancer cells, and this may be a common feature among carcinoma.

Synthesis and preliminary investigations into novel 1,2,3-triazole-derived androgen receptor antagonists inspired by bicalutamide.

A versatile and high yielding synthesis of novel androgen receptor (AR) antagonists is presented. Using this methodology, six 1,4-substituted-1,2,3-triazole derived bicalutamide mimics were synthesised in five steps and in isolated overall yields from 41% to 85%. Evaluation of these compounds for their anti-proliferative properties against androgen dependent (LNCaP) and independent (PC-3) cells showed promising IC50 values of 34-45 μM and 29-151 μM, respectively. The data suggest that the latter compounds may be an excellent starting point for the development of prostate cancer therapeutics for both androgen dependent and independent forms of this disease. Docking of these compounds (each enantiomer) in silico into the T877A mutated androgen receptor, as possessed by LNCaP cells, was also undertaken.

Targeting HSP90/survivin using a cell permeable structure based peptido-mimetic shepherdin in retinoblastoma

BACKGROUND: Retinoblastoma (RB) is a childhood retinal malignancy. Effective therapeutic strategies are still being investigated in RB disease management. Here, the anti-cancer effect of shepherdin, a peptido-mimetic inhibiting heat shock protein (HSP90)-Survivin interaction has been analyzed. METHODS: We analyzed HSP (HSP70/90) and Survivin protein expressions by immunohistochemistry (29 archival tumors), qRT-PCR, FACS and Western analysis (10 un-fixed RB tumors). We also analyzed cellular cytotoxicity and anti-proliferative effect in peptide treated RB cells (Y79, Weri Rb1) and MIO-M1 cells. RESULTS: Heterogeneous expressions of HSP70/90 and Survivin with a significant association between HSP70 and HSP90 (r(2) = 0.59, p = 0.001) was observed. In RB cells, anti-tumor effects were detected with 0.42 μg/ml of shepherdin at 4 h s of serum starvation. Decreased Survivin, Bcl2, MMP-2 activity with increased Bax, Bim, and Caspase-9 protein expressions were noticed. No significant changes were observed in shepherdin treated non-neoplastic MIO-M1, nor in scramble-peptide treated RB cells. CONCLUSION: The presence of HSPs (HSP70/90) and Survivin reveals multiple cellular mechanisms adopted by RB cells during cancer progression. Serum starvation induced HSP90 whose interactions with Survivin were specifically inhibited by shepherdin. The associated molecular shuffling has been reported. These findings strongly implicate the potential of targeting HSP90-Survivin interaction as an adjuvant therapy in RB management.