In normal adult fibroblasts, transforming growth factor-␤ (TGF␤) induces the expression of connective tissue growth factor (CTGF). CTGF independently promotes fibroblast proliferation and matrix deposition, and in acute models of fibrosis promotes cell proliferation and collagen deposition acting synergistically with TGF␤. In contrast to normal fibroblasts, fibroblasts cultured from fibrotic tissues express high basal levels of CTGF, even in the absence of added TGF␤. Induction of transcription by TGF␤ requires the action of SMAD proteins. In this report we have investigated the role of SMADs in the TGF␤-induction of CTGF in normal fibroblasts and in the elevated levels of CTGF expression found in dermal fibroblasts cultured from lesional areas of patients with scleroderma, a progressive fibrotic disorder that can affect all organs of the body. We have identified a functional SMAD binding site in the CTGF promoter. TGF␤-induction of CTGF is dependent on SMAD3 and SMAD4 but not SMAD2 and is p300-independent. However, mutation of the SMAD binding site does not reduce the high level of CTGF promoter activity observed in dermal fibroblasts cultured from lesional areas of scleroderma patients. Conversely, the previously termed TGF␤RE in the CTGF promoter is required for basal CTGF promoter activity in normal fibroblasts and for the elevated level of CTGF promoter activity in scleroderma fibroblasts. Thus, the maintenance of the fibrotic phenotype in scleroderma fibroblasts, as visualized by excess CTGF expression, appears to be independent of SMAD-dependent TGF␤ signaling. Furthermore, given CTGF's activities, the high level of CTGF expression observed in scleroderma lesions may contribute to the excessive scarring observed in this disorder.

Connective tissue growth factor (CTGF) is overexpressed in a variety of fibrotic disorders, presumably secondary to the activation and production of transforming growth factor-␤ (TGF-␤), a key inducer of fibroblast proliferation and matrix synthesis. The CTGF gene promoter has a TGF-␤ response element that regulates its expression in fibroblasts but not epithelial cells or lymphocytes. Recent studies have shown that the macrophage-produced cytokine tumor necrosis factor ␣ (TNF␣) is necessary to promote inflammation and to induce genes, such as matrix metalloproteinases, involved with the early stages of wound healing. In this study, we examined the ability of TNF␣ to modulate CTGF gene expression. TNF␣ was found to suppress the TGF-␤-induced expression of CTGF protein in cultured normal fibroblasts. The activity of TNF␣ was blocked by NF-B inhibitors. We showed that sequences between ؊244 and ؊166 of the CTGF promoter were necessary for both TGF-␤ and TNF␣ to modulate CTGF expression. There was a constitutive expression of CTGF by scleroderma fibroblasts that was increased by TGF-␤ treatment. Although TNF␣ was able to repress TGF-␤-induced CTGF and collagen synthesis both in normal and scleroderma skin fibroblasts, fibroblasts cultured from scleroderma patients were more resistant to TNF␣ as TNF␣ was unable to suppress the basal level of CTGF expression in scleroderma fibroblasts. Thus, we suspect that the high level of constitutive CTGF expression in scleroderma fibroblasts and its inability to respond to negative regulatory cytokines may contribute to the excessive scarring of skin and internal organs in patients with scleroderma.

The TGF-beta-induction of CTGF in mesangial cells requires SMADs and PKC/ras/MEK/ERK pathways. SMADs are involved in basal CTGF expression, which presumably reflects the fact that mesangial cells express TGF-beta endogenously. TGF-beta also induces CTGF through ras/MEK/ERK. Inhibiting ras/MEK/ERK seems not to reduce phosphorylation (that is, activation) of SMADs, suggesting that SMADs, although necessary, are insufficient for the TGF-beta-stimulation of the CTGF promoter through ras/MEK/ERK. Thus, maximal TGF-beta induction of CTGF requires synergy between SMAD and ras/MEK/ERK signaling.

The TGF-beta-induction of CTGF in mesangial cells requires SMADs and PKC/ras/MEK/ERK pathways. SMADs are involved in basal CTGF expression, which presumably reflects the fact that mesangial cells express TGF-beta endogenously. TGF-beta also induces CTGF through ras/MEK/ERK. Inhibiting ras/MEK/ERK seems not to reduce phosphorylation (that is, activation) of SMADs, suggesting that SMADs, although necessary, are insufficient for the TGF-beta-stimulation of the CTGF promoter through ras/MEK/ERK. Thus, maximal TGF-beta induction of CTGF requires synergy between SMAD and ras/MEK/ERK signaling.

BAFF (also known as BLyS), a member of the tumor necrosis factor superfamily, plays a critical role in the maturation and development of B cells. BAFF has three receptors on B cells, the most crucial of which is BR3. In this study, we demonstrate the biological outcome of BAFF blockade in cynomolgus monkeys using a soluble fusion protein consisting of human BR3 and human IgG1 Fc. In vitro, BR3-Fc blocked BAFF-mediated survival and proliferation of cynomolgus monkey B cells. Weekly treatment of cynomolgus monkeys with BR3-Fc for 13 to 18 weeks resulted in significant B-cell reduction in the peripheral blood and in lymphoid organs. CD21(high) B cells in lymphoid tissues, a subset analogous to human marginal zone B cells, expressed nearly twofold higher BR3 levels than did CD21(med) B cells. Lymphoid tissue flow cytometric analysis showed that BR3-Fc reduced this CD21(high) B-cell subset to a greater extent than it reduced CD21(med) B cells. Dual-label immunohistochemistry and morphometric image analysis supported these results by demonstrating that BR3-Fc reduced a significant proportion of the B cells within the splenic inner and outer marginal zones. These findings should prove very useful in guiding the desired therapeutic use of BR3-Fc for autoimmune diseases in the clinic.

The trypsin-like serine protease marapsin is a member of the large protease gene cluster at human chromosome 16p13.3, which also contains the structurally related proteases testisin, tryptase ⑀, tryptase ␥, and EOS. To gain insight into the biological functions of marapsin, we undertook a detailed gene expression analysis. It showed that marapsin expression was restricted to tissues containing stratified squamous epithelia and was absent or only weakly expressed in all other tissues, including the pancreas. Marapsin was constitutively expressed in nonkeratinizing stratified squamous epithelia of human esophagus, tonsil, cervix, larynx, and cornea. In the keratinizing stratified squamous epidermis of skin, however, its expression was induced only during epidermal hyperproliferation, such as in psoriasis and in murine wound healing. In fact, marapsin was the second most strongly up-regulated protease in psoriatic lesions, where expression was localized to the upper region of the hyperplastic epidermis. Similarly, in the hyperproliferative epithelium of regenerating murine skin wounds, marapsin localized to the suprabasal layers, where keratinocytes undergo squamous differentiation. The transient up-regulation of marapsin, which closely correlated with re-epithelialization, was virtually absent in a genetic mouse model of delayed wound closure. These results suggested a function during the process of re-epithelialization. Furthermore, in reconstituted human epidermis, a model system of epidermal differentiation, members of the IL-20 subfamily of cytokines, such as IL-22, induced marapsin expression. Consistent with a physiologic role in marapsin regulation, IL-22 was also strongly expressed in re-epithelializing skin wounds. Marapsin's restricted expression, localization, and cytokine-inducible expression suggest a role in the terminal differentiation of keratinocytes in hyperproliferating squamous epithelia.Marapsin (PRSS27; also known as pancreasin) is a trypsinlike serine protease and member of the large serine protease gene cluster at human chromosome 16p13.3 and mouse chromosome 17A3.3, respectively (1, 2). Based on conserved features of the propeptides and the activation mechanism, these proteases were divided into two groups (2). Marapsin belongs to the group-1 subfamily of the human cluster, which includes testisin (PRSS21, eosinophil serine protease-1), tryptase ⑀ (PRSS22, brain-specific serine protease-4), tryptase ␥ (PRSS31, transmembrane tryptase), and EOS (PRSS33). They all contain a relatively short propeptide, which, after activation cleavage of the single chain precursor, remains attached to the protease domain via a disulfide bond. In contrast, the propeptides of group-2 subfamily members tryptase ␣, tryptase ␤1, tryptase ␤2, and tryptase ␦ are not disulfide-linked to the protease domain and are released upon activation cleavage.The 268-amino acid single-chain precursor form (zymogen) of human marapsin is converted into the active enzyme by proteolytic cleavage at the Arg 34 -Met 35 peptide bond. T...

SignificanceThe ubiquitin ligase CRL4COP1/DET1 modifies specific transcription factor substrates with polyubiquitin so that they are degraded. However, the Ras–MEK–ERK signaling pathway can inactivate CRL4COP1/DET1 and thereby promote the rapid accumulation of these transcription factors. Here we show that constitutive photomorphogenesis 1 (COP1) has a critical role in mouse brain development because its deletion from neural stem cells stabilizes the transcription factors c-JUN, ETV1, ETV4, and ETV5, leading to perturbation of normal gene expression patterns; anatomic anomalies in cerebral cortex, hippocampus, and cerebellum; and perinatal lethality.

Background MEHD is a novel dual-action humanized IgG1 antibody that blocks ligand binding to EGFR and HER3, inhibiting all major ligand-dependent HER complex signaling. Preclinical and Phase 1a clinical data suggested ligand-driven HER3 signaling as a promising target for therapy in a subset of patients with SCCHN. Results from the MEHGAN study showed comparable objective response rates and PFS for MEHD and Cet (Fayette et al, ESMO 2014). Here we report the results of comprehensive and comparative biomarker analyses from that study. Methods Archival and fresh (as available) tumor tissues were evaluated to characterize the biology of anti-HER therapy in SCCHN, and to identify potential predictive biomarkers for improved outcomes with MEHD compared to Cet, with particular attention to the HER3 ligand NRG1. NRG1 and ERBB3 RNA expression was measured by both ISH (data analysis are ongoing) and qRT-PCR. Additionally, extensive gene expression analyses and HPV detection were performed by qRT-PCR. Results Of 121 randomized patients in MEHGAN, 107 had archival tissues with sufficient tumor content and quality for biomarker analyses. Key findings include: 1) Most patients with CT RECIST responses on either treatment arm had higher (≥ median) tumor expression levels of NRG1 as measured by qRT-PCR 2) EGFR ligands such as amphiregulin were co-expressed with NRG1, consistent with preclinical analysis in an independent panel of SCCHN tumor samples (Genentech data on file). 3) 24 HPV (+) patients (20%) were identified, consistent with published prevalence reports. 4) Higher EGFR and HER3 ligand expression was observed in HPV (-) samples relative to HPV (+) samples and, moreover, no responses were seen in HPV (+) patients. These results are consistent with prior correlative ligand observations and may point to differential roles for HER signaling biology in HPV (-) versus HPV (+) SCCHN. Conclusions NRG1 expression did not predict enhanced responsiveness to MEHD versus Cet or, conversely, resistance to Cet. NRG1 and EGFR ligands appear to have similar expression patterns in SCCHN. Higher levels of NRG1 and EGFR ligands were associated with greater activity for both MEHD and Cet, and were consistently observed in HPV (-) SCCHN versus HPV (+) SCCHN. These data suggest distinct HER signaling biology in these 2 patient groups and warrant further evaluation to potentially inform treatment approaches in SCCHN. * We would like acknowledge and thank all of the MEHGAN study investigators and patients. Citation Format: Elicia Penuel, Amy V. Kapp, An Do, Rachel Tam, Teiko Sumiyoshi, Chaitra Marathe, Susan Sa, Franklin Peale, Mark Lackner, Scott Holden, Tanguy Seiwert, Andrea Pirzkall. Biomarker evaluation in a randomized phase 2 study of MEHD7945A (MEHD) versus cetuximab (Cet) in ≥2 line recurrent/metastatic (R/M) squamous cell carcinomas of the head and neck (SCCHN) [MEHGAN]. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1553. doi:10.1158/1538-7445.AM2015-1553