Inhibition of retinol oxidation by ethanol in the rat liver and colon

BACKGROUND—Epidemiological evidence has been presented for an increased risk of development of colon cancer after chronic alcohol abuse. Alcohol is degraded by cytosolic alcohol dehydrogenases that also are capable of retinol oxidation. Inhibition of retinol oxidation to retinoic acid has been shown to occur in parallel with profound impairment of intracellular retinoid signal transduction and loss of cell differentiation control.
AIMS—In the present study, the change in cytosolic retinol oxidation and retinoic acid formation by ethanol concentrations that occur in body tissues in humans after social drinking was measured in cells from the liver, and small and large intestine of the rat.
RESULTS—The specific catalytic efficiency V(max)/K(m) (ml/min/g) of cytosolic retinol oxidation in the large intestine (28.9) was found to be distinctly higher than that in the liver (3.4), while the efficiency in the small intestine was negligible (0.20). In the presence of increasing ethanol concentrations (9, 17, and 34 mM), V(max)/K(m) for retinol oxidation decreased in a dose dependent manner to 7.8% of the initial value in the large intestine and to 12% in the liver. The V(max)/K(m) of retinoic acid formation in the liver cytosol decreased to 15%.
CONCLUSIONS—Our data demonstrate impairment of hepatic and intestinal cytosolic retinol oxidation and retinoic acid formation by ethanol at concentrations in body tissues after social drinking in humans. The results suggest that the increased risk of developing colorectal neoplasias after alcohol abuse may, at least in part, be caused by impaired retinoid signal transduction.


Keywords: retinol; retinoic acid; ethanol; alcohol; alcohol dehydrogenases; intestin

Phenotyping and target expression profiling of CD34+/CD38- and CD34+/CD38+ stem- and progenitor cells in acute lymphoblastic leukemia

Leukemic stem cells (LSCs) are an emerging target of curative anti-leukemia therapy. In acute lymphoblastic leukemia (ALL), LSCs frequently express CD34 and often lack CD38. However, little is known about markers and targets expressed in ALL LSCs. We have examined marker- and target expression profiles in CD34+/CD38- LSCs in patients with Ph+ ALL (n = 22) and Ph- ALL (n = 27) by multi-color flow cytometry and qPCR. ALL LSCs expressed CD19 (B4), CD44 (Pgp-1), CD123 (IL-3RA), and CD184 (CXCR4) in all patients tested. Moreover, in various subgroups of patients, LSCs also displayed CD20 (MS4A1) (10/41 = 24%), CD22 (12/20 = 60%), CD33 (Siglec-3) (20/48 = 42%), CD52 (CAMPATH-1) (17/40 = 43%), IL-1RAP (13/29 = 45%), and/or CD135 (FLT3) (4/20 = 20%). CD25 (IL-2RA) and CD26 (DPPIV) were expressed on LSCs in Ph+ ALL exhibiting BCR/ABL1p210, whereas in Ph+ ALL with BCR/ABL1p190, LSCs variably expressed CD25 but did not express CD26. In Ph- ALL, CD34+/CD38- LSCs expressed IL-1RAP in 6/18 patients (33%), but did not express CD25 or CD26. Normal stem cells stained negative for CD25, CD26 and IL-1RAP, and expressed only low amounts of CD52. In xenotransplantation experiments, CD34+/CD38- and CD34+/CD38+ cells engrafted NSG mice after 12-20 weeks, and targeting with antibodies against CD33 and CD52 resulted in reduced engraftment. Together, LSCs in Ph+ and Ph- ALL display unique marker- and target expression profiles. In Ph+ ALL with BCR/ABL1p210, the LSC-phenotype closely resembles the marker-profile of CD34+/CD38- LSCs in chronic myeloid leukemia, confirming the close biologic relationship of these neoplasms. Targeting of LSCs with specific antibodies or related immunotherapies may facilitate LSC eradication in ALL

PAK-dependent STAT5 serine phosphorylation is required for BCR-ABL-induced leukemogenesis

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Perspectives on the Future of Ice Nucleation Research: Research Needs and Unanswered Questions Identified from Two International Workshops

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