NSG-Pro mouse model for uncovering resistance mechanisms and unique vulnerabilities in human luminal breast cancers.

Most breast cancer deaths are caused by estrogen receptor-α–positive (ER) disease. Preclinical progress is hampered by a shortage of therapy-naïve ER tumor models that recapitulate metastatic progression and clinically relevant therapy resistance. Human prolactin (hPRL) is a risk factor for primary and metastatic ER breast cancer.

Loss of Nuclear Localized Parathyroid Hormone-Related Protein in Primary Breast Cancer Predicts Poor Clinical Outcome and Correlates with Suppressed Stat5 Signaling.

Purpose: Parathyroid hormone-related protein (PTHrP) is required for normal mammary gland development and biology. A gene polymorphism is associated with breast cancer risk, and PTHrP promotes growth of osteolytic breast cancer bone metastases. Accordingly, current dogma holds that PTHrP is upregulated in malignant primary breast tumors, but solid evidence for this assumption is missing.

Prolactin-Stat5 signaling in breast cancer is potently disrupted by acidosis within the tumor microenvironment.

Introduction: Emerging evidence in estrogen receptor-positive breast cancer supports the notion that prolactin-Stat5 signaling promotes survival and maintenance of differentiated luminal cells, and loss of nuclear tyrosine phosphorylated Stat5 (Nuc-pYStat5) in clinical breast cancer is associated with increased risk of antiestrogen therapy failure. However, the molecular mechanisms underlying loss of Nuc-pYStat5 in breast cancer remain poorly defined.

Methods: We investigated whether moderate extracellular acidosis of pH 6.

PTP1B suppresses prolactin activation of Stat5 in breast cancer cells.

Basal levels of nuclear localized, tyrosine phosphorylated Stat5 are present in healthy human breast epithelia. In contrast, Stat5 phosphorylation is frequently lost during breast cancer progression, a finding that correlates with loss of histological differentiation and poor patient prognosis. Identifying the mechanisms underlying loss of Stat5 phosphorylation could provide novel targets for breast cancer therapy.

Protocol for constructing tissue arrays by cutting edge matrix assembly.

We present a protocol for construction of high-density tissue microarrays, cutting edge matrix assembly, which is based on repetitive sectioning and bonding of tissues. Maximized array density is achieved by a scaffold-free, self-supporting construction with rectangular array features that are bonded edge-to-edge, resulting in minimal wasted space between samples. Construction of the tissue array blocks from paraffin-embedded tissue involves initial bonding of primary tissue plates into multiple primary tissue stacks.

Prolactin inhibits BCL6 expression in breast cancer through a Stat5a-dependent mechanism.

BCL6 is a transcriptional repressor that recognizes DNA target sequences similar to those recognized by signal transducer and activator of transcriptions 5 (Stat5). BCL6 disrupts differentiation of breast epithelia, is downregulated during lactation, and is upregulated in poorly differentiated breast cancer. In contrast, Stat5a mediates prolactin-induced differentiation of mammary epithelia, and loss of Stat5 signaling in human breast cancer is associated with undifferentiated histology and poor prognosis.

Cyclin D1 splice variants: polymorphism, risk, and isoform-specific regulation in prostate cancer.

Purpose: Alternative CCND1 splicing results in cyclin D1b, which has specialized, protumorigenic functions in prostate not shared by the cyclin D1a (full length) isoform. Here, the frequency, tumor relevance, and mechanisms controlling cyclin D1b were challenged.

Experimental Design: First, relative expression of both cyclin D1 isoforms was determined in prostate adenocarcinomas.

Insensitivity of human prolactin receptors to nonhuman prolactins: relevance for experimental modeling of prolactin receptor-expressing human cells.

Prolactin (PRL) receptors are expressed in a broad range of human cell types and in a majority of human breast and prostate cancers. Experimentally, normal and malignant human cells are typically cultured in vitro in media containing bovine PRL (bPRL) from fetal bovine serum or as xenotransplants in vivo in the presence of murine PRL (mPRL). The biological efficacy of bPRL toward hPRL receptors (hPRLR) is controversial, and hPRLR are insensitive to mPRL, but the mechanism is not known.

Cyclin D1b is aberrantly regulated in response to therapeutic challenge and promotes resistance to estrogen antagonists.

Cyclin D1 is a key mediator of cell cycle progression that is aberrantly regulated in multiple cancers, especially in breast cancers. A number of studies have indicated that a polymorphism in a splice donor site in the cyclin D1 gene is associated with alternative splicing and the production of the alternative cyclin D1b transcript. Furthermore, this polymorphism is selectively associated with disease outcomes.

Insulin receptor substrate-1 regulates the transformed phenotype of BT-20 human mammary cancer cells.

Although originating from a human breast cancer, BT-20 cells do not form colonies in soft agar. BT-20 cells do not express insulin receptor substrate-1 (IRS-1), which is known to promote both normal and abnormal growth and to inhibit differentiation. Stable expression of IRS-1 confers to BT-20 cells the ability to form colonies in soft agar.

Ultrahigh density microarrays of solid samples.

We present a sectioning and bonding technology to make ultrahigh density microarrays of solid samples, cutting edge matrix assembly (CEMA). Maximized array density is achieved by a scaffold-free, self-supporting construction with rectangular array features that are incrementally scalable. This platform technology facilitates arrays of >10,000 tissue features on a standard glass slide, inclusion of unique sample identifiers for improved manual or automated tracking, and oriented arraying of stratified or polarized samples.

Phosphorylation of BATF regulates DNA binding: a novel mechanism for AP-1 (activator protein-1) regulation.

BATF is a member of the AP-1 (activator protein-1) family of bZIP (basic leucine zipper) transcription factors that form transcriptionally inhibitory, DNA binding heterodimers with Jun proteins. In the present study, we demonstrate that BATF is phosphorylated in vivo on multiple serine and threonine residues and at least one tyrosine residue. Reverse-polarity PAGE revealed that serine-43 and threonine-48 within the DNA binding domain of BATF are phosphorylated.