Oral 9-cis retinoic acid (Alitretinoin) in the treatment of myelodysplastic syndromes: results from a pilot study

Prolymphangiogenic Effects of 9-cis Retinoic Acid Are Enhanced at Sites of Lymphatic Injury and Dependent on Treatment Duration in Experimental Postsurgical Lymphedema

Background: Patients undergoing surgical treatment for solid tumors are at risk for development of secondary lymphedema due to intraoperative lymphatic vessel injury. The damaged lymphatic vessels fail to adequately regenerate and lymphatic obstruction leads to fluid and protein accumulation in the interstitial space and chronic lymphedema develops as a result. There are currently no effective pharmacological agents that reduce the risk of developing lymphedema or treat pre-existing lymphedema, and management is largely palliative. The present study investigated the efficacy of various 9-cis retinoic acid (9-cis RA) dosing strategies in reducing postsurgical lymphedema by utilizing a well-established mouse tail lymphedema model. Methods and Results: Short-duration treatment with 9-cis RA did not demonstrate a significant reduction in postoperative tail volume, nor an improvement in lymphatic clearance. However, long-term treatment with 9-cis RA resulted in decreased overall tail volume, dermal thickness, and epidermal thickness, with an associated increase in functional lymphatic clearance and lymphatic vessel density, assessed by LYVE-1 immunostaining, compared with control. These effects were seen at the site of lymphatic injury, with no significant changes observed in uninjured sites such as ear skin and the diaphragm. Conclusions: Given the reported results indicating that 9-cis RA is a potent promoter of lymphangiogenesis and improved lymphatic clearance at sites of lymphatic injury, investigation of postoperative 9-cis RA administration to patients at high risk of developing lymphedema may demonstrate positive efficacy and reduced rates of postsurgical lymphedema.

A novel all-trans retinoic acid derivative regulates cell cycle and differentiation of myelodysplastic syndrome cells by USO1

4-Amino-2-Trifluoromethyl-Phenyl Retinate (ATPR), a novel all-trans retinoic acid (ATRA) derivative, has been demonstrated that it had a variety of anti-tumor effects by exerting regulation on cellular proliferation, apoptosis and differentiation. Here, we found that ATPR is critical for alleviating myelodysplastic syndrome (MDS) and acute myelogenous leukemia. USO1, vesicle transport factor, belongs to tether protein family and involved in endoplasmic reticulum to Golgi trafficking of protein which is important to tumorigenesis. How USO1 contribute to MDS remain elusive. USO1 is aberrantly activated in MDS and AML in vivo and vitro, aberration of which might be a dominant mechanism for MDS cell survival. During the ATPR-induced remission of MDS, in vitro, USO1 presents a time and concentration-dependent decrease. Silencing of USO1 promotes myeloid differentiation of MDS cells and inhibits MDS cellular proliferation while USO1 over-expression has the opposite effect, suggesting that reduction of USO1 enhances the sensitivity of SKM-1 cells to ATPR treatment. Mechanistically, USO1 exerts its oncogenic role by inactivating Raf/ERK signaling, while ATPR is access to revise it. Notably, the activity of Raf/ERK pathway is required for the development and maintenance of MDS cell proliferation. Collectively, our results demonstrate the USO1- Raf/ERK signaling axis in MDS and highlight the negative role of USO1 in ATPR-regulated remission of MDS.

Identification of Biomarkers Modulated by the Rexinoid LGD1069 (Bexarotene) in Human Breast Cells Using Oligonucleotide Arrays

Retinoids have been found to be promising chemopreventive agents that play an important role in regulating cell growth, differentiation, and apoptosis. The action of retinoids is mediated by retinoid receptors (retinoic acid receptors and retinoid X receptors), which are nuclear transcription factors that, when bound to retinoids, regulate gene expression. LGD1069 is a highly selective RXR agonist that has reduced toxicity compared with retinoids. Our previous studies have shown that RXR-selective ligands (or "rexinoids"), including LGD1069, can inhibit the growth of normal and malignant breast cells and can suppress the development of breast cancer in transgenic mice. For the current study, we attempted to identify biomarkers of the chemopreventive effect of the RXR-selective retinoid LGD1069. In these experiments, we used Affymetrix microarrays to identify target genes that were modulated by LGD1069 in normal human breast cells. Affymetrix and dChip analysis identified more than 100 genes that were up-regulated or down-regulated by LGD1069 treatment. We then tested 16 of these genes in validation experiments using quantitative reverse transcription-PCR and Western blotting of independently prepared samples, and found that 15 of 16 genes were modulated in a similar manner in these validation experiments as in the microarray experiments. Genes found to be regulated include known retinoid-regulated genes, growth regulatory genes, transcription factors, and differentiation markers. We then showed that the expression of several of these rexinoid-regulated biomarkers is modulated in vivo in mammary glands from mice treated with LGD1069. These critical growth-regulating proteins will be promising targets of future agents for the prevention and treatment of breast cancer.

The myelodysplastic syndromes: diagnosis and treatment

The myelodysplastic syndromes (MDSs) are common, acquired, clinically challenging hematologic conditions that are characterized by bone marrow failure and a risk of progression to acute leukemia. These disorders can arise de novo, especially in elderly patients or, less often, as a consequence of prior chemotherapy or radiotherapy for an unrelated disease. The MDS classification systems were revised recently and updated. These refined classification and prognostic schemes help stratify patients by their risk of leukemia progression and death; this knowledge can help clinicians select appropriate therapy. Although many treatments for MDS have been proposed and evaluated, at present, only hematopoietic stem cell transplantation offers any real hope for cure, and no available therapy beyond general supportive care offers benefit to more than a minority of patients. However, recent clinical trials enrolling patients with MDS have reported encouraging results with use of newer drugs, including lenalidomide, decitabine, and darbepoetin alfa. Other exciting treatment regimens are being tested. Here, we present a contemporary, practical clinical approach to the diagnosis and risk-stratified treatment of MDS. We review when to suspect MDS, detail how to evaluate patients who may have a form of the condition, explain key features of treatments that are currently available in the United States, and summarize a general, common-sense therapeutic approach to patients with MDS.

The myelodysplastic syndrome(s): a perspective and review highlighting current controversies

The myelodysplastic syndrome (MDS) includes a diverse group of clonal and potentially malignant bone marrow disorders characterized by ineffective and inadequate hematopoiesis. The presumed source of MDS is a genetically injured early marrow progenitor cell or pluripotential hematopoietic stem cell. The blood dyscrasias that fall under the broad diagnostic rubric of MDS appear to be quite heterogeneous, which has made it very difficult to construct a coherent, universally applicable MDS classification scheme. A recent re-classification proposal sponsored by the World Health Organization (WHO) has engendered considerable controversy. Although the precise incidence of MDS is uncertain, it has become clear that MDS is at least as common as acute myelogenous leukemia (AML). There is considerable overlap between these two conditions, and the former often segues into the latter; indeed, the distinction between AML and MDS can be murky, and some have argued that the current definitions are arbitrary. Despite the discovery of several tantalizing pathophysiological clues, the basic biology of MDS is incompletely understood. Treatment at present is generally frustrating and ineffective, and except for the small subset of patients who exhibit mild marrow dysfunction and low-risk cytogenetic lesions, the overall prognosis remains rather grim. In this narrative review, we highlight recent developments and controversies within the context of current knowledge about this mysterious and fascinating cluster of bone marrow failure states.