In women with hormone-dependent breast cancer, tamoxifen (TAM) frequently induces tumor regression, but regrowth occurs with continuation of antiestrogen therapy. Studies of breast xenografts in nude mice suggest that this secondary resistance to TAM may reflect the development of enhanced sensitivity to the estrogenic properties of TAM. In the current study, we examined the hypothesis that TAM...

This investigation examines the tamoxifen (TAM)-dependent growth in vivo of an MCF-7 tumor variant, MCF-7TAM, previously reported in this journal (M. M. Gottardis and V. C. Jordan, Cancer Res., 48: 5183-5187, 1988). Ovariectomized athymic mice were implanted with 1-mm3 pieces of MCF-7TAM and were treated with Silastic capsules of varying sizes containing TAM to demonstrate dose-dependent growth...

PURPOSE The antiestrogen tamoxifen (Tam) has been used as therapy against estrogen receptor (ER)-positive breast cancer for decades. Most tumors respond initially, but resistance frequently develops. The ER exists in a multiprotein complex containing the molecular chaperone heat shock protein (Hsp) 90, which is known to regulate the stability and activity of this receptor. Therefore, we investi...

Tamoxifen (TAM) has been shown to induce apoptosis in breast cancer cells. bcl-2 family genes, which can interact with each other, have been shown to interfere with apoptosis after various stimuli. In this study, we investigated the effects of TAM on bcl-2 family gene products bcl-2, bax, and bcl-X(L) and on p53 levels in estrogen receptor-positive MCF-7 breast cancer cells. We found that TAM i...

Multifocal tumor recurrence of glioblastomas occurs in up to 14% of patients. In a parallel phase-II-study investigating post-operative treatment with tamoxifen (TAM), carboplatin and radiation therapy for glioblastomas, 16 of 49 patients (33%) showed multifocal recurrence, which developed after a mean of 46 weeks, raising the question of an association with therapy. We studied the interrelatio...

Estrogen receptor (ER)-positive breast cancer patients may turn ER-negative and develop acquired drug resistance, which compromises the efficacy of endocrine therapy. By investigating the phenomenon that gefitinib can re-sensitise tamoxifen (TAM)-resistant MCF-7 breast cancer cells (MCF-7/TAM) to TAM, the present study verified that gefitinib could reverse the acquired drug resistance in endocr...

BACKGROUND Exactly what role does tumor-derived Fas ligand (FasL) play in cancer: maintaining the immune privilege site or inducing a pro-inflammatory effect? One possible hypothesis is that tumor-associated macrophages (TAM) act as the mediator that enables apoptosis of anti-tumor immune cells without FasL-related inflammation. We have evaluated the tumor FasL expression and TAM along the tumo...

Cancer nanotherapeutics is beginning to overwhelm the global research and viewed to be the revolutionary treatment regime in the medical field. This investigation describes the development of a stable nanostructured lipid carrier (NLC) system as carrier for Tamoxifen (TAM). The TAM-loaded NLC (TAM-NLC) developed with 200mg of TAM showed a spherical particle with the size of 46.6nm, polydispersi...

Choline kinase-α (Chk-α) and autophagy have gained much attention, as they relate to the drug-resistance of breast cancer. Here, we explored the potential connection between Chk-α and autophagy in the mechanisms driving to tamoxifen (TAM) resistance, in estrogen receptor positive (ER+) breast cancer cells (BCCs). Human BCC lines (MCF-7 and TAM-resistant MCF-7 (MCF-7/TAM) cells) were used. Chk-α...