Collagen Crosslinking for Keratoconus: Cellular Signaling Mechanisms.

Collagen crosslinking (CXL) is a widely used treatment to halt the progression of keratoconus (KC). Unfortunately, a significant number of patients with progressive KC will not qualify for CXL, including those with corneas thinner than 400 µm. The present study aimed to investigate the molecular effects of CXL using in vitro models, mirroring the normal, as well as thinner corneal stroma seen in KCs. Primary human corneal stromal cells were isolated from healthy (HCFs) and keratoconus (HKCs) donors. Cells were cultured and stimulated with stable Vitamin C resulting in 3D self-assembled extracellular matrix (ECM), cell-embedded, constructs. CXL was performed on (a) thin ECM with CXL performed at week 2 and (b) normal ECM with CXL performed at week 4. Constructs without CXL served as controls. All constructs were processed for protein analysis. The results showed modulation of Wnt signaling, following CXL treatment, as measured by the protein levels of Wnt7b and Wnt10a, correlated to the expression of α-smooth muscle actin (SMA). Further, the expression of a recently identified KC biomarker candidate, prolactin-induced protein (PIP), was positively impacted by CXL in HKCs. CXL-driven upregulation of PGC-1 and the downregulation of SRC and Cyclin D1 in HKCs were also noted. Although the cellular/molecular impacts of CXL are largely understudied, our studies provide an approximation to the complex mechanisms of KC and CXL. Further studies are warranted to determine factors influencing CXL outcomes.

Secreted indicators of androgen receptor activity in breast cancer pre-clinical models.

PURPOSE: Accumulating evidence has attracted attention to the androgen receptor (AR) as a biomarker and therapeutic target in breast cancer. We hypothesized that AR activity within the tumor has clinical implications and investigated whether androgen responsive serum factors might serve as a minimally invasive indicator of tumor AR activity. METHODS: Based on a comprehensive gene expression analysis of an AR-positive, triple negative breast cancer patient-derived xenograft (PDX) model, 163 dihydrotestosterone (DHT)-responsive genes were defined as an androgen responsive gene set. Among them, we focused on genes that were DHT-responsive that encode secreted proteins, namely KLK3, AZGP1 and PIP, that encode the secreted factors prostate specific antigen (PSA), zinc-alpha-2-glycoprotein (ZAG) and prolactin induced protein (PIP), respectively. Using AR-positive breast cancer cell lines representing all breast cancer subtypes, expression of candidate factors was assessed in response to agonist DHT and antagonist enzalutamide. Gene set enrichment analysis (GSEA) was performed on publically available gene expression datasets from breast cancer patients to analyze the relationship between genes encoding the secreted factors and other androgen responsive gene sets in each breast cancer subtype. RESULTS: Anti-androgen treatment decreased proliferation in all cell lines tested representing various tumor subtypes. Expression of the secreted factors was regulated by AR activation in the majority of breast cancer cell lines. In GSEA, the candidate genes were positively correlated with an androgen responsive gene set across breast cancer subtypes. CONCLUSION: KLK3, AZGP1 and PIP are AR regulated and reflect tumor AR activity. Further investigations are needed to examine the potential efficacy of these factors as serum biomarkers.

Prolactin Induced Protein (PIP) is a potential biomarker for early stage and malignant breast cancer.

OBJECTIVES: Breast cancer (BC) is the second leading cause of cancer-related mortality in women. Bioinformatic analysis and expression screening showed that Prolactin Induced Protein (PIP) was differentially expressed in BC. The objective of this investigation was to characterize the expression pattern of PIP, an aspartyl proteinase, in malignant and non-malignant breast tissues. MATERIALS AND METHODS: Real time quantitative PCR was employed to analyze PIP and androgen receptor (AR) mRNA levels in BC cell lines and 190 normal tissues and tumor samples. The tumor specimens were categorized based on TNM classification, anatomic stage, histologic grade and molecular subtype and expression pattern evaluated. To detect protein levels, immunohistochemistry followed by semi quantitative scoring was employed in the examination of 517 normal, benign, and invasive BC tissues. RESULTS: We observed substantial downregulation of PIP transcription in cancer samples compared to normal breast tissue. mRNA levels were significantly downregulated (93 fold, P < 0.005) in advanced grades compared to lower grades. Transcript levels were also significantly lower (22 fold, P < 0.05) in triple negative tumors compared to hormone receptor positive tumors. Significant downregulation was observed in early stage samples of triple negative and hormone receptor positive tumors. Though PIP protein showed a wide range of expression levels in BC, early stage samples showed significant downregulation. CONCLUSIONS: PIP mRNA is significantly downregulated in early stage BC compared to normal breast tissue. Consequently, low PIP mRNA expression in BC tissues could potentially be used as a tissue based biomarker to assist pathologists in confirmation of early stage BC diagnosis.