Summary Human breast cancers that exhibit high proportions of immune cells and elevated levels of proinflammatory cytokines predict poor prognosis. Here, we demonstrate that treatment of human MCF-7 breast cancer cells with pro-inflammatory cytokines results in ERα-dependent activation of gene expression and proliferation, in the absence of ligand or presence of 4OH-tamoxifen (TOT). Cytokine activation of ERα and endocrine resistance is dependent on phosphorylation of ERα at S305 in the hinge domain. Phosphorylation of S305 by IKKβ establishes an ERα cistrome that substantially overlaps with the estradiol (E2)-dependent ERα cistrome. Structural analyses suggest that S305-P forms a charge-linked bridge with the C-terminal F domain of ERα that enables inter-domain communication and constitutive activity from the N-terminal coactivator-binding site, revealing the structural basis of endocrine resistance. ERα therefore functions as a transcriptional effector of cytokine-induced IKKβ signaling, suggesting a mechanism through which the tumor microenvironment controls tumor progression and endocrine resistance.

A late preterm infant with intrauterine growth restriction developed respiratory distress, tachypnoea and hypoxia after birth, requiring supplemental oxygen. Chest radiographs demonstrated persistent elevation of the right hemidiaphragm. Chest ultrasound initially demonstrated symmetrical bilateral diaphragm motion, but subsequent ultrasounds showed asymmetrical excursion with weaker movement of the right hemidiaphragm. Placental pathology demonstrated chronic infectious villitis secondary to cytomegalovirus (CMV), and subsequent CMV testing on the infant was positive. The infant was microcephalic and head imaging revealed intracranial calcifications, consistent with congenital CMV infection.CMV is the most common congenital infection and has a wide array of clinical manifestations. This report highlights the rarely described association between congenital CMV infection and respiratory distress due to underlying diaphragm dysfunction. In neonates with respiratory distress and features of congenital CMV infection, clinicians should have a high index of suspicion for diaphragm dysfunction.

In breast cancer, infiltration of macrophages establishes an inflammatory tumor microenvironment, which can foster an extremely aggressive and therapy resistant tumor. Although inflammatory cytokines are known to modulate the transcriptional potential of estrogens and contribute to an endocrine-resistant state in cell-based model systems, the underlying molecular mechanisms remain poorly defined. We have used the human breast cancer cell-line MCF-7, an estrogen receptor α(ERα) positive and inflammatory cytokine sensitive cell line, to define the global impact inflammatory cytokines on the ERα cistrome and ERα-dependent transcriptional activity using next-generation sequencing methods. IL-1β and TNFα treatments establish an ERα cistrome that substantially overlaps with the E2-dependent ERα cistrome and results in ERα-dependent, ligand-independent activation of gene expression. Cytokine stimulation of MCF-7 cells results in phosphorylation of ERα at S305 which drives the ligand-independent activation of ERα. Pharmacological inhibition of IKKα/β blocks cytokine-dependent S305 phosphorylation, inhibits the cytokine-dependent ERα cistome, and abolishes cytokine-dependent gene activation. Additionally, S305 phosphorylation by cytokine treatments blocks the ability of tamoxifen to inhibit the expression of a subset of E2-dependent target genes and mutation of S305 to alanine restores tamoxifen sensitivity in the presence of IL-1β or TNFα. Collectively, these results provide molecular details dictating how inflammatory cytokines activate the transcriptional potential of ERα and drive an endocrine-resistant state in human breast cancer cells. In addition, they highlight the potential for anti-inflammatory therapies to be utilized in the treatment of patients with tamoxifen-resistant breast cancer. Citation Format: Joshua D. Stender, Irida Kastrati, Maayan Yakir, Jonna Frasor, Christopher K. Glass. Inflammatory cytokines alter the sensitivity of breast cancer cells to endocrine treatments. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-148. doi:10.1158/1538-7445.AM2014-LB-148