Human Semaphorin 6B [(HSA)SEMA6B], A Novel Human Class 6 Semaphorin Gene: Alternative Splicing and All-Trans-Retinoic Acid-Dependent Downregulation in Glioblastoma Cell Lines

All-trans retinoic acid (atRA) regulates gene expression and is used to treat acute promyelocytic leukemia. Attempts to use atRA in breast cancer without a stratification strategy have resulted in limited overall effectiveness. To identify biomarkers for the treatment of triple-negative breast cancer (TNBC) with atRA, we characterized the effects of atRA on the tumor growth of 13 TNBC cell lines. This resulted in a range of effects that was not predictable based on previously hypothesized predictors of response, such as the levels of atRA nuclear shuttling proteins fatty acid binding protein 5 (FABP5) and cellular retinoic acid binding protein 2 (CRABP2). Transcriptional profiling revealed that atRA induced distinct gene expression changes in the sensitive versus resistant cell lines that were mostly independent of the presence of retinoic acid response elements (RAREs) or peroxisome proliferator response elements (PPREs). Given the importance of DNA methylation in regulating gene expression, we hypothesized that differential DNA methylation could predict the response of TNBCs to atRA. We identified over 1400 sites that were differentially methylated between atRA resistant and sensitive cell lines. These CpG sites predicted the response of four TNBC patient-derived xenografts to atRA, and we utilized these xenografts to refine the profile and identified that as many as 17% of TNBC patients could benefit from atRA treatment. These data illustrate that differential methylation of specific CpGs may be useful biomarkers for predicting the response of patient tumors to atRA treatment.

Download Full-text

Effect of six retinoids and retinoic acid catabolic inhibitor liarozole on two glioblastoma cell lines, and in-vivo experience in malignant brain tumor patients

Cancer Treatment An Update ◽

10.1007/978-2-8178-0765-2_126 ◽

1994 ◽

pp. 590-598 ◽

Cited By ~ 1

Author(s):

M. E. Westarp ◽

M. P. Westarp ◽

W. Bollag ◽

J. Bruynseels ◽

H. Biesalski ◽

...

Keyword(s):

Brain Tumor ◽

Retinoic Acid ◽

Cell Lines ◽

Malignant Brain Tumor ◽

Glioblastoma Cell ◽

Tumor Patients ◽

Glioblastoma Cell Lines

Download Full-text

All-trans retinoic acid enhances, and a pan-RAR antagonist counteracts, the stem cell promoting activity of EVI1 in acute myeloid leukemia

Cell Death and Disease ◽

10.1038/s41419-019-2172-2 ◽

2019 ◽

Vol 10 (12) ◽

Cited By ~ 5

Author(s):

Chi Huu Nguyen ◽

Katharina Bauer ◽

Hubert Hackl ◽

Angela Schlerka ◽

Elisabeth Koller ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Stem Cell ◽

Retinoic Acid ◽

Cell Lines ◽

Myeloid Leukemia ◽

Leukemic Cells ◽

Dependent Manner ◽

Trans Retinoic Acid ◽

All Trans Retinoic Acid ◽

Acute Myeloid

AbstractEcotropic virus integration site 1 (EVI1), whose overexpression characterizes a particularly aggressive subtype of acute myeloid leukemia (AML), enhanced anti-leukemic activities of all-trans retinoic acid (atRA) in cell lines and patient samples. However, the drivers of leukemia formation, therapy resistance, and relapse are leukemic stem cells (LSCs), whose properties were hardly reflected in these experimental setups. The present study was designed to address the effects of, and interactions between, EVI1 and retinoids in AML LSCs. We report that Evi1 reduced the maturation of leukemic cells and promoted the abundance, quiescence, and activity of LSCs in an MLL-AF9-driven mouse model of AML. atRA further augmented these effects in an Evi1 dependent manner. EVI1 also strongly enhanced atRA regulated gene transcription in LSC enriched cells. One of their jointly regulated targets, Notch4, was an important mediator of their effects on leukemic stemness. In vitro exposure of leukemic cells to a pan-RAR antagonist caused effects opposite to those of atRA. In vivo antagonist treatment delayed leukemogenesis and reduced LSC abundance, quiescence, and activity in Evi1high AML. Key results were confirmed in human myeloid cell lines retaining some stem cell characteristics as well as in primary human AML samples. In summary, our study is the first to report the importance of EVI1 for key properties of AML LSCs. Furthermore, it shows that atRA enhances, and a pan-RAR antagonist counteracts, the effects of EVI1 on AML stemness, thus raising the possibility of using RAR antagonists in the therapy of EVI1high AML.

Download Full-text