Estrogen Receptor-positive Cancer Patients Research Articles

MicroRNAs control the function of telomeres in cancer

Telomeres are located at the end of chromosomes and consist of DNA tandem repeats that recruit the specialized protein complex “shelterin”. Shelterin has a crucial role in controlling chromosome end protection, telomere recombination and telomere length. Telomeres shorten with every cell division, finally leading to telomere-dysfunction and the induction of senescence or apoptosis. Cancer formation is paralleled by a change in telomere regulation. Re-activation of telomerase ensures the maintenance of telomere function to facilitate unlimited proliferative potential. Importantly, aberrant function of the shelterin complex contributes to tumor formation and genomic instability in human cancer. miRNAs are important regulators of central cancer pathways and are of high clinical relevance. We recently showed that the onco-microRNA miR-155 controls the expression of TRF1 in human breast cancer to promote increased telomere fragility and genomic instability. Importantly, low TRF1 expression correlates with poor prognosis in estrogen receptor positive cancer patients, underlining the clinical relevance of miR-155 dependent regulation of TRF1 in human breast cancer. Our work suggests that multiple miRNAs exist that control telomere function in telomere related pathologies. Identification and functional validation of “telo-miRNAs” is expected to open new avenues in the understanding of telomere related maladies such as cancer and aging.

Response of advanced breast cancer to total endocrine ablation after exacerbation on tamoxifen: Results in seven patients and possible mechanism of action

Usage of tamoxifen in the treatment of advanced breast cancer is increasing and is advocated by some authors as primary therapy in all estrogen receptor positive cancer patients. Tamoxifen is an incomplete estrogen antagonist with partial estrogen agonist activity as well. Tamoxifen-induced exacerbation of breast cancer ("tamoxifen flare") is reported to occur in 4-20% or more of treated patients. Management of this condition has varied from stopping treatment to continued administration or reinstitution of tamoxifen after flare symptoms subside. Responses have occurred in some patients so treated, although the remissions do not appear durable. The seven patients with advanced breast cancer in this report experienced disease exacerbation with tamoxifen therapy. Endocrine ablation afforded all patients excellent pain relief and disease control with prolonged survival in six of the seven. There have been no studies directly examining the disease course in flare patients continuing on tamoxifen. Persistence in treating these patients with an incomplete antagonist-agonist may deprive them of full survival benefit possible through ablative procedures when used in sequential treatment.