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Anaplastic thyroid carcinoma (ATC) is an extremely malignant type of endocrine cancer frequently accompanied by extrathyroidal extension or metastasis through mechanisms that remain elusive. We screened for the CREB3 transcription - factor family in a large cohort, consisting of four microarray datasets. This revealed that CREB3L1 was specifically up regulated in ATC tissues and negatively associated with overall survival of patients with thyroid cancer. Consistently, high expression of CREB3L1 was negatively correlated with progression - free survival in an independent cohort. CREB3L1 knockdown dramatically attenuated invasion of ATC cells, whereas overexpression of CREB3L1 facilitated the invasion of papillary thyroid carcinoma (PTC) cells. Loss of CREB3L1 inhibited metastasis and tumor growth of ATC xenografts in zebrafish and nude mouse model. Single - cell RNA-sequencing analysis revealed that CREB3L1 expression gradually increased during the neoplastic progression of a thyroid follicular epithelial cell to an ATC cell, accompanied by the activation of the extracellular matrix (ECM) signaling. CREB3L1 knockdown significantly decreased the expression of collagen subtypes in ATC cells and the fibrillar collagen in xenografts. Due to the loss of CREB3L1, ATC cells were unable to activate alpha - smooth muscle actin (α - SMA) - positive cancer - associated fibroblasts (CAFs). After CREB3L1 knockdown, the presence of CAFs inhibited the growth of ATC spheroids and the metastasis of ATC cells. Further cytokine array screening showed that ATC cells activated α - SMA - positive CAFs through CREB3L1 - mediated IL - 1α production. Moreover, KPNA2 mediated the nuclear translocation of CREB3L1, thus allowing it to activate downstream ECM signaling. These results demonstrate that CREB3L1 maintains the CAF - like property of ATC cells by activating the ECM signaling, which remodels the tumor stromal microenvironment and drives the malignancy of ATC. Graphical Abstract

Background Women with metastatic breast cancer have a disheartening 5-year survival rate of only 28%. CREB3L1 (cAMP responsive element binding protein 3 like 1) is a transcription factor and tumor suppressor which is downregulated in ~ 30% of human breast cancers, with higher frequencies in more advanced metastatic breast tumors. Methods To identify new targets contributing to metastatic properties, we carried out a differential gene expression analysis between highly metastatic breast cancer cells with low CREB3L1 and the corresponding lines expressing HA-CREB3L1. This analysis was carried out across three different subtypes of breast cancer cells (T47D, HCC1954 and HCC1806; all CREB3L1-low). Key signaling pathways and cell functions most impacted by CREB3L1 expression were identified using a bioinformatics analysis. Specific genes consistently upregulated in the metastatic cells were knocked down to assess their impact on cell migration, cell invasion, growth in soft agar across in multiple breast cancer lines. The effect of knocking down the top metastatic gene identified in this study was further tested using in vivo mouse model of primary breast tumor growth in the mammary fat pad, and metastatic colonization of the lung. Results Breast cancer cells with low CREB3L1 expression showed upregulation of metastasis and integrin signaling pathways and enhanced cell movement, migration, invasion functions, consistent with its known role as a tumor suppressor. CLIC3 (chloride intracellular channel 3), a protein with roles in integrin recycling, cell migration and invasion, was found to be consistently upregulated in CREB3L1-low cells and in all subtypes of breast tumors. Increased CLIC3 expression was associated with poor patient survival. Knockdown of CLIC3 in several cell lines reduced cell migration, invasion and anchorage-independent growth in soft agar, effects that could be rescued by co-transfection of an sh RNA-insensitive CLIC3 plasmid. CLIC3 knockdown also decreased tumor growth and blocked metastases in a mouse xenograft model of breast cancer. Conclusions These results suggest that CLIC3 has a key role in promoting cell migration, invasion and growth in soft agar, and CLIC3 inhibitors may be a viable treatment option for breast cancer.

Purpose Osteogenesis imperfecta (OI) is a heritable skeletal dysplasia. Dominant pathogenic variants in COL1A1 and COL1A2 explain the majority of OI cases. At least 15 additional genes have been identified, but those still do not account for all OI phenotypes that present. We sought the genetic cause of mild and lethal OI phenotypes in an unsolved family. Methods We performed exome sequencing on seven members of the family, both affected and unaffected. Results We identified a variant in cyclic AMP responsive element binding protein 3-like 1 ( CREB3L1 ) in a consanguineous family. The variant caused a prenatal/perinatal lethal OI in homozygotes, similar to that seen in OI type II as a result of mutations in type I collagen genes, and a mild phenotype (fractures, blue sclerae) in multiple heterozygous family members. CREB3L1 encodes old astrocyte specifically induced substance (OASIS), an endoplasmic reticulum stress transducer. The variant disrupts a DNA-binding site and prevents OASIS from acting on its transcriptional targets including SEC24D , which encodes a component of the coat protein II complex. Conclusion This report confirms that CREB3L1 is an OI-related gene and suggests the pathogenic mechanism of CREB3L1 -associated OI involves the altered regulation of proteins involved in cellular secretion.

Background Doxorubicin-based chemotherapy is currently the most frequently used treatment for triple negative breast cancer (TNBC), yet the response rate is not high due to the lack of a biomarker allowing identification of responsive patients before the chemotherapy is initiated. We have demonstrated that doxorubicin inhibits proliferation of cancer cells through proteolytic activation of a transcription factor called CREB3L1 (cAMP response element binding protein 3-like 1), and that CREB3L1 expression in cancer cells is a key determinant of their sensitivity to doxorubicin when they are cultured in vitro or established as xenograft tumors in mice. The purpose of this study is to determine whether CREB3L1 expression in tumor cells of TNBC patients can be established as a biomarker to predict outcomes of doxorubicin-based chemotherapy. Methods We performed a retrospective analysis on breast core biopsy tissue samples taken from 18 TNBC patients before they were treated with doxorubicin-based chemotherapy. CREB3L1 expression in the cancer cells was analyzed by immunohistochemistry and quantified using the Immunoreactive Score (IRS). Outcomes of the chemotherapy were measured by the residual cancer burden (RCB) system. Results CREB3L1 expression levels in TNBC responsive to doxorubicin-based chemotherapy (RCB class 0-2) were significantly higher than that in resistant cancers (RCB class 3) (unpaired two-tailed t test, p = 0.0005; Statistical power 99.8 at 95% confidence level). All cancers expressing higher levels of CREB3L1 (IRS 4-12) responded to doxorubicin-based chemotherapy, whereas all cancers resisting the treatment expressed lower levels of CREB3L1 (IRS 0-3). Conclusions These results suggest that CREB3L1 expression level may be used as a biomarker to identify TNBC patients who are more likely to benefit from doxorubicin-based chemotherapy.

Osteogenesis imperfecta (OI) is a clinically and genetically heterogeneous brittle bone disorder. Whereas dominant OI is mostly due to heterozygous mutations in either COL1A1 or COL1A2 , encoding type I procollagen, recessive OI is caused by biallelic mutations in genes encoding proteins involved in type I procollagen processing or chaperoning. Hitherto, some OI cases remain molecularly unexplained. We detected a homozygous genomic deletion of CREB3L1 in a family with severe OI. CREB3L1 encodes OASIS, an endoplasmic reticulum-stress transducer that regulates type I procollagen expression during murine bone formation. This is the first report linking CREB3L1 to human recessive OI, thereby expanding the OI gene spectrum.

Background CREB3L1 (cAMP-responsive element-binding protein 3-like protein 1), a member of the unfolded protein response, has recently been identified as a metastasis suppressor in both breast and bladder cancer. Methods Quantitative real time PCR (qPCR) and immunoblotting were used to determine the impact of histone deacetylation and DNA methylation inhibitors on CREB3L1 expression in breast cancer cell lines. Breast cancer cell lines and tumor samples were analyzed similarly, and CREB3L1 gene methylation was determined using sodium bisulfite conversion and DNA sequencing. Immunohistochemistry was used to determine nuclear versus cytoplasmic CREB3L1 protein. Large breast cancer database analyses were carried out to examine relationships between CREB3L1 gene methylation and mRNA expression in addition to CREB3L1 mRNA expression and prognosis. Results This study demonstrates that the low CREB3L1 expression previously seen in highly metastatic breast cancer cell lines is caused in part by epigenetic silencing. Treatment of several highly metastatic breast cancer cell lines that had low CREB3L1 expression with DNA methyltransferase and histone deacetylase inhibitors induced expression of CREB3L1, both mRNA and protein. In human breast tumors, CREB3L1 mRNA expression was upregulated in low and medium-grade tumors, most frequently of the luminal and HER2 amplified subtypes. In contrast, CREB3L1 expression was repressed in high-grade tumors, and its loss was most frequently associated with triple negative breast cancers (TNBCs). Importantly, bioinformatics analyses of tumor databases support these findings, with methylation of the CREB3L1 gene associated with TNBCs, and strongly negatively correlated with CREB3L1 mRNA expression. Decreased CREB3L1 mRNA expression was associated with increased tumor grade and reduced progression-free survival. An immunohistochemistry analysis revealed that low-grade breast tumors frequently had nuclear CREB3L1 protein, in contrast to the high-grade breast tumors in which CREB3L1 was cytoplasmic, suggesting that differential localization may also regulate CREB3L1 effectiveness in metastasis suppression. Conclusions Our data further strengthens the role for CREB3L1 as a metastasis suppressor in breast cancer and demonstrates that epigenetic silencing is a major regulator of the loss of CREB3L1 expression. We also highlight that CREB3L1 expression is frequently altered in many cancer types suggesting that it could have a broader role in cancer progression and metastasis.

Discrimination of Philadelphia‐negative myeloproliferative neoplasms (Ph‐MPNs) from reactive hypercytosis and myelofibrosis requires a constellation of testing including driver mutation analysis and bone marrow biopsies. We searched for a biomarker that can more easily distinguish Ph‐MPNs from reactive hypercytosis and myelofibrosis by using RNA‐seq analysis utilizing platelet‐rich plasma (PRP)‐derived RNAs from patients with essential thrombocythemia (ET) and reactive thrombocytosis, and CREB3L1 was found to have an extremely high impact in discriminating the two disorders. To validate and further explore the result, expression levels of CREB3L1 in PRP were quantified by reverse‐transcription quantitative PCR and compared among patients with ET, other Ph‐MPNs, chronic myeloid leukemia (CML), and reactive hypercytosis and myelofibrosis. A CREB3L1 expression cutoff value determined based on PRP of 18 healthy volunteers accurately discriminated 150 driver mutation–positive Ph‐MPNs from other entities (71 reactive hypercytosis and myelofibrosis, 6 CML, and 18 healthy volunteers) and showed both sensitivity and specificity of 1.0000. Importantly, CREB3L1 expression levels were significantly higher in ET compared with reactive thrombocytosis (P < .0001), and polycythemia vera compared with reactive erythrocytosis (P < .0001). Pathology‐affirmed triple‐negative ET (TN‐ET) patients were divided into a high– and low–CREB3L1‐expression group, and some patients in the low‐expression group achieved a spontaneous remission during the clinical course. In conclusion, CREB3L1 analysis has the potential to single‐handedly discriminate driver mutation–positive Ph‐MPNs from reactive hypercytosis and myelofibrosis, and also may identify a subgroup within TN‐ET showing distinct clinical features including spontaneous remission. CREB3L1 expression in platelet RNA can completely discriminate Philadelphia‐negative myeloproliferative neoplasms from other entities including reactive hypercytosis and myelofibrosis. The sensitivity and specificity of this testing are both 1.0000.

Sclerosing epithelioid fibrosarcoma (SEF) occurring as a primary bone tumor is exceptionally uncommon. Even more rare are cases of SEF that show morphologic overlap with low-grade fibromyxoid sarcoma (LGFMS). Such hybrid lesions arising within the bone have only rarely been reported in the literature. Due to their variegated histomorphology and non-specific radiologic features, these tumors may pose diagnostic difficulties. Herein we describe three molecularly confirmed primary bone cases of sclerosing epithelioid fibrosarcoma that demonstrated prominent areas showing the features of LGFMS and with areas resembling so-called hyalinizing spindle cell tumor with giant rosettes (HSCTGR). Two patients were female and one was male aged 26, 47, and 16, respectively. The tumors occurred in the femoral head, clavicle, and temporal bone. Imaging studies demonstrated relatively well-circumscribed radiolucent bone lesions with enhancement on MRI. Cortical breakthrough and soft tissue extension were present in one case. Histologically the tumors all demonstrated hyalinized areas with SEF-like morphology as well as spindled and myxoid areas with LGFMS-like morphology. Two cases demonstrated focal areas with rosette-like architecture as seen in HSCTGR. The tumors were all positive for MUC4 by immunohistochemistry and cytogenetics, fluorescence in-situ hybridization, and next-generation sequencing studies identified EWSR1 gene rearrangements confirming the diagnosis in all three cases.Hybrid SEF is exceedingly rare as a primary bone tumor and can be difficult to distinguish from other low-grade spindled and epithelioid lesions of bone. MUC4 positivity and identification of underlying EWSR1 gene rearrangements help support this diagnosis and exclude other tumor types.

A new mechanism involving cleavage of a transcription factor called CREB3L1 has been proposed to explain the anti-tumour effects of doxorubicin.A new mechanism involving cleavage of a transcription factor called CREB3L1 has been proposed to explain the anti-tumour effects of doxorubicin.

Background: Fibrotic remodelling of the lamina cribrosa (LC) is a defining pathological feature of glaucomatous optic neuropathy and contributes to progressive optic nerve head deformation and axonal vulnerability. LC cells from glaucomatous donors exhibit a myofibroblast-like phenotype characterised by excessive extracellular matrix (ECM) production, a process associated with chronic cellular stress. cAMP responsive element-binding protein 3-like 1 (CREB3L1) is an endoplasmic reticulum–resident transcription factor implicated in stress-responsive regulation of collagen synthesis and matrix homeostasis. The role of CREB3L1 in glaucomatous LC cells, however, remains poorly defined. Methods: Primary human LC cells derived from donors with confirmed glaucoma (GLC; n = 3) and age-matched non-glaucomatous controls (NLC; n = 3) were examined. CREB3L1 expression was assessed at the mRNA and protein levels using quantitative RT-PCR and Western immunoblotting. The functional effects of CREB3L1 suppression were evaluated using siRNA-mediated knockdown in GLC cells, followed by analysis of ECM gene transcription (α-smooth muscle actin, collagen type I alpha 1, fibronectin) and cellular metabolic activity using an MTS assay. Results: CREB3L1 mRNA and protein expression were significantly elevated in GLC cells compared with NLC cells. siRNA-mediated knockdown of CREB3L1 effectively reduced its expression in GLC cells and was associated with significant suppression of profibrotic ECM gene transcription. In addition, CREB3L1 knockdown resulted in a marked reduction in cellular metabolic activity in glaucomatous LC cells. Conclusions: These findings identify CREB3L1 as a regulator of ECM-associated gene expression and cellular behaviour in glaucomatous lamina cribrosa cells. While preliminary, the data suggest that CREB3L1 may contribute to pathological fibrotic remodelling at the optic nerve head. Further mechanistic and in vivo studies will be required to determine whether modulation of CREB3L1-mediated pathways represents a viable therapeutic strategy in glaucoma.