Jackie Papkoff

Activated β-catenin induces osteoblast differentiation of C3H10T1/2 cells and participates in BMP2 mediated signal transduction

Abstract Wnt glycoproteins are important regulators of cellular differentiation and embryonic development. Some Wnt proteins induce stabilization of β-catenin which cooperatively regulates gene expression with LEF/Tcf transcription factors. Here we demonstrate a direct role for β-catenin signaling in osteoblast differentiation and in BMP2-mediated signal transduction. Similar to treatment with BMP-2 protein, ectopic expression of stabilized β-catenin in C3H10T1/2 cells or activation of endogenous β-catenin signaling with LiCl induces expression of alkaline phosphatase mRNA and protein, a defined marker of early osteoblast differentiation. Unlike BMP2 protein, stabilized β-catenin does not induce osteocalcin gene expression, a marker of late osteoblast differentiation. BMP2-induced differentiation also leads to activation of endogenous β-catenin signaling thus implicating β-catenin in early steps of BMP2-mediated osteoblast differentiation. Effects of β-catenin and BMP2 on C3H10T1/2 differentiation are not completely overlapping, implying that some aspects of BMP2-induced differentiation may be mediated by β-catenin signaling and that β-catenin can also participate in non-BMP2-dependent differentiation processes.

B7-H4 Is Highly Expressed in Ductal and Lobular Breast Cancer

Purpose: This study was designed to investigate the expression of B7-H4 protein, a member of the B7 family that is involved in the regulation of antigen-specific immune responses, in normal breast and in primary and metastatic breast carcinomas. Experimental Design: Archival formalin-fixed tissue blocks from breast cancers and normal somatic tissues were evaluated for B7-H4 expression by immunohistochemistry with manual and automated image analysis. The proportion of B7-H4-positive cells and the intensity of B7-H4 staining were compared with histologic type, grade, stage, hormone receptor status, and HER-2/neu status. Results: B7-H4 was detected in 165 of 173 (95.4%) primary breast cancers and in 240 of 246 (97.6%) metastatic breast cancers. B7-H4 staining intensity was greater in invasive ductal carcinomas [24.61 relative units (RU)] and in invasive lobular carcinomas (15.23 RU) than in normal breast epithelium (4.30 RU, P = 0.0003). Increased staining intensity was associated with negative progesterone receptor status (P = 0.014) and history of neoadjuvant chemotherapy (P = 0.004), and the proportion of B7-H4-positive cells was associated with negative progesterone receptor (P = 0.001) and negative HER-2/neu (P = 0.024) status. However, there was no statistically significant relationship between the proportion of B7-H4-positive cells or staining intensity and grade, stage, or other clinicopathologic variables. Low levels of B7-H4 expression were also detected in epithelial cells of the female genital tract, lung, pancreas, and kidney, but B7-H4 was generally absent in most other normal somatic tissues. Conclusions: The nearly ubiquitous expression of B7-H4 in breast cancer, independent of tumor grade or stage, suggests a critical role for this protein in breast cancer biology.

Nox1 is over‐expressed in human colon cancers and correlates with activating mutations in K‐Ras

The NADPH‐oxidase 1 (Nox1) is a homolog of gp91phox, the catalytic subunit of the phagocyte superoxide‐generating NADPH‐oxidase. Nox1 is expressed in normal colon epithelial cells and in colon tumor cell lines, and overexpression in model cells has been implicated in stimulation of mitogenesis and angiogenesis and inhibition of apoptosis. This suggests that aberrant expression of Nox1 could contribute to the development of colorectal cancer. Herein, we examine the expression of Nox1 mRNA in 24 colon tumors of various stages compared with paired adjacent normal tissue from the same patient, and correlate expression with some common mutations associated with colon cancer. Nox1 was overexpressed compared with paired normal tissue in 57% of tumors as early as the adenoma stage, with no correlation of expression level with tumor stage. Overexpression of Nox1 mRNA correlated with Nox1 protein levels assessed by immunofluorescence and immunohistochemistry with an antibody specific for Nox1. There was a strong correlation between Nox1 mRNA level and activating mutations in codons 12 and 13 of K‐Ras. Eighty percent (8/10) of tumors with codons 12 and 13 mutations had a 2‐fold or more increase in Nox1 mRNA, and 70% (7/10) had a 5‐fold or greater increase. Transgenic mice expressing K‐RasG12V in the intestinal epithelium also expressed markedly elevated Nox1 in both small and large intestine. There was no correlation between inactivating mutations in the tumor suppressor p53 and Nox1 expression. We conclude that Nox1 mRNA and protein are overexpressed in colon cancer and are strongly correlated with activating mutations in K‐Ras.

Detection of B7-H4 and p53 in pancreatic cancer: potential role as a cytological diagnostic adjunct.

Objectives: This study compared p53 expression with B7-H4, a novel cancer biomarker, in pancreatic ductal adenocarcinoma (PDA) resection specimens and in a pilot series of endoscopic ultrasound-guided fine-needle aspirations (EUS-FNAs). Methods: B7-H4 and p53 expression were evaluated by immunoperoxidase methods in 36 PDA and 15 EUS-FNA specimens and were scored for intensity and proportion of positive cells; cases were then assigned a final sum score. Results: B7-H4 was detected in 33 (92%) of 36 PDA sections, 8 (89%) of 9 cytologically positive EUS-FNAs, and 1 (20%) of 5 cytologically negative EUS-FNAs. p53 was detected in 30 (83%) of 36 PDA sections, 4 (44%) of 9 cytologically positive EUS-FNAs, and 1 (20%) of 5 cytologically negative cases. One EUS-FNA case that was cytologically atypical but not diagnostic of malignancy expressed B7-H4 and p53. Some benign tissue components (intercalated cells/ducts, main pancreatic ducts, and acinar cells) were also positive for B7-H4 and/or p53. Overall expression of B7-H4 in benign tissues, however, was relatively low compared with that seen in most carcinoma cases. Conclusions: B7-H4 was expressed more often in PDA than was p53. Despite potentially problematic expression in benign/normal cells, the 2 markers target different cellular components and demonstrate potential diagnostic use for detection of PDA in resected and EUS-FNA specimens.

B7-h4 expression in a range of breast pathology: correlation with tumor T-cell infiltration.

B7-H4, a member of the B7 family, is involved in the regulation of antigen-specific immune responses. Its expression in a range of breast pathology and correlation to the number of CD3+ and CD8+ tumor infiltrating T-lymphocytes in invasive carcinomas were explored. The proportion of B7-H4 positive cells, staining pattern, and intensity were evaluated within diagnostic groups (normal and benign lesional, potentially premalignant and in situ carcinoma, and invasive carcinoma) on archival tissue blocks by immunohistochemistry. The proportion and intensity of B7-H4 expression was progressively increased across the major diagnostic groups. There was a significant association between a high proportion of B7-H4 positive cells in invasive ductal carcinomas and decreased number of tumor infiltrating lymphocytes (P=0.002). The cellular distribution of B7-H4 appears altered in the spectrum of normal to malignant breast. Its overexpression may help cancers avoid immune detection.