Rétinoïdes : mécanismes d’action

The Role of ATRA, Natural Ligand of Retinoic Acid Receptors, on EMT-Related Proteins in Breast Cancer: Minireview

The knowledge of the structure, function, and abundance of specific proteins related to the EMT process is essential for developing effective diagnostic approaches to cancer with the perspective of diagnosis and therapy of malignancies. The success of all-trans retinoic acid (ATRA) differentiation therapy in acute promyelocytic leukemia has stimulated studies in the treatment of other tumors with ATRA. This review will discuss the impact of ATRA use, emphasizing epithelial-mesenchymal transition (EMT) proteins in breast cancer, of which metastasis and recurrence are major causes of death.

The association between carotenoids and subjects with overweight or obesity: a systematic review and meta-analysis

BACKGROUND

Excess body weight, including overweight and obesity, is one of the major factors influencing human health, and plays an important role in the global burden of disease. Carotenoids serve as precursors of vitamin A-related retinoids, and are considered to have potential effects on many diseases. However, the influence of carotenoids on people with excess body weight is unclear.

METHODS

This meta-analysis was conducted to assess the effects of carotenoids on overweight or obese subjects utilizing the available evidence. We searched PubMed, Medline, Cochrane Library, Web of Science and EMBASE databases up to September 2020. Random effects models were used to calculate the standard mean differences (SMDs) and odds ratios (ORs) with their 95% confidence intervals (95% CIs).

RESULTS

A total of seven randomized controlled trials and eight observational studies met the inclusion criteria and contained 28 944 subjects and data on multiple carotenoid subgroups, including lycopene, astaxanthin, cryptoxanthin, α-carotene, and β-carotene. In all included Randomized Controlled Trial (RCT), the intervention duration was 20 days at the shortest and 16 weeks at the longest, and the range of intervention doses was 1.2-60 mg d-1. Our study found that the insufficiency of serum carotenoids was a risk factor for overweight and obesity (OR = 1.73, 95% CI [1.57, 1.91], p < 0.001). Moreover, carotenoid supplementation was significantly associated with body weight reductions (SMD = -2.34 kg, 95% CI [-3.80, -0.87] kg, p < 0.001), body mass index decrease (BMI, SMD = -0.95 kg cm-2, 95% CI [-1.88, -0.01] kg cm-2, p < 0.001) and waist circumference losses (WC, SMD = -1.84 cm, 95% CI [-3.14, -0.54]cm, p < 0.001).

CONCLUSION

In summary, the carotenoids show promising effects in overweight or obese subjects. Additional data from large clinical trials are needed.

Cancer prevention and treatment using combination therapy with natural compounds

Introduction: Naturally occurring compounds play an essential role in the prevention and treatment of various cancers. There are more than 100 plant and animal based natural compounds currently in clinical use.Areas covered: 1) The importance of natural products combinations in the prevention and treatment of cancer, 2) the need to maximize efficacy while minimizing side effects when using natural product combinations, and 3) specifics related to plant and animal derived natural products, as well as agents derived from natural products. Therapies using natural compounds that have been investigated, their rationale, mechanism of action and findings are reviewed. When the data warrant it, combined interventions that appear to increase efficacy (compared with monotherapy) while minimizing toxicity have been highlighted. Pubmed was used to search for relevant publications.Expert opinion: Combination therapy with natural compounds has the potential to be more effective than single agent therapy. Similar to pharmacologic agents, the goal is to maximize efficacy while mimimizing potential side effects. There is an increasing research focus on the development of agents derived from natural products, with notable successes already achieved from the effort.

Expression of retinoid receptors in hand eczema

BACKGROUND

Hand eczema is the most common occupational skin disease. The etiology is multifactorial. Systemic alitretinoin, a pan-retinoic receptor agonist, has proven efficacy in the treatment of recalcitrant chronic hand eczema; however, its precise mechanism of action in hand eczema is not fully understood.

AIMS

Assessment of the level of expression of retinoid receptors (RAR and RXR) in the skin of patients with hand eczema in an attempt to explain their possible role in the pathogenesis of the disease.

METHODS

Thirty patients with hand eczema and 30 age- and sex-matched healthy controls were included. Full clinical examination was done, and tissue levels of retinoic acid receptor (RAR) and retinoid x receptor (RXR) were measured by quantitative real-time PCR (qRT-PCR).

RESULTS

The levels of RAR and RXR expression were significantly downregulated in the patient group compared to the control group; (P < 0.001) for both. In addition, there was a statistically significant negative correlation between Osnabrück Hand Eczema Severity Index (OHSI) and the levels of RAR and RXR expression (P < 0.001).

CONCLUSION

Deficient retinoid receptor expression has a primary role in the pathogenesis, clinical phenotype, and severity of hand eczema and sheds light on the mechanism of action of retinoids in the treatment of chronic hand eczema.

The polymorphisms of growth factor genes (VEGFA & EGF) were associated with response to acitretin in psoriasis

Aim: VEGF and EGF are assumed to be involved in the pathogenesis of psoriasis, while the impacts of their polymorphisms on psoriasis are inconsistent. Therefore, we hope to clarify these relationships in the Chinese Han population. Methods: A total of 131 patients with psoriasis vulgaris and 176 controls were enrolled. The polymorphisms rs833061 (T > C), rs10434 (G > A) in VEGFA, and rs4444903 (G > A), rs2237051 (A > G) in EGF of each participant were detected. The patients were treated with calcipotriol plus acitretin 30 mg/day for 8 weeks. Results: No SNPs of rs833061, rs10434, rs4444903 and rs2237051 were found to be associated with psoriasis susceptibility and efficacy. Although the mutation of rs10434A was associated with baseline disease severity (p = 0.026), and rs2237051G allele was associated with increased erythema during treatment (p = 0.015). Conclusion: The allele of rs2237051 G increased the erythema during the treatment, and no polymorphism of VEGF and EGF gene was found to be associated with the susceptibility and efficacy in psoriasis.

Guidelines for the use of acitretin in psoriasis. Psoriasis Group of the Spanish Academy of Dermatology and Venereology

Phototherapy, classic systemic treatments (methotrexate, acitretin, and ciclosporin), and biologic agents (etanercept, infliximab, adalimumab, and ustekinumab) constitute a broad therapeutic arsenal that increases the likelihood of achieving control of severe and extensive disease in patients with psoriasis. Acitretin continues to be a very valuable tool in both monotherapy, in which it is combined with other systemic treatments (classic or biologic), and in sequential therapy. Thanks to its lack of a direct immunosuppressive effect and its ability to achieve a long-term response, acitretin has an important role in the treatment of psoriasis, although this has not always been acknowledged in relevant treatment guidelines. We present consensus guidelines for the use of acitretin in psoriasis drawn up by the Psoriasis Group of the Spanish Academy of Dermatology and Venereology. These guidelines provide a detailed account of acitretin, including pharmacological properties, indications and contraindications, adverse effects, and factors that should be taken into account to enhance the safe use of this drug. They also propose treatment strategies for use in routine clinical practice. The overall aim of these guidelines is to define the criteria for the use and management of acetretin in psoriasis.

Contribution of retinoid X receptor signaling to the specification of skeletal muscle lineage

Pluripotent stem cells possess a tremendous potential for the treatment of many diseases because of their capacity to differentiate into a variety of cell lineages. However, they provide little promise for muscle-related diseases, mainly because of the lack of small molecule inducers to efficiently direct myogenic conversion. Retinoic acid, acting through the retinoic acid receptor (RAR) and retinoid X receptor (RXR), affects stem cell fate determination in a concentration-dependent manner, but it only has a modest efficacy on the commitment of ES cells into skeletal muscle lineage. The RXR is very important for embryonic development but is generally considered to act as a silent partner of RAR in a non-permissive mode. In this study, we have examined whether activation of the RXR by rexinoid or RXR-specific signaling play a role in the specification of stem cells into muscle lineage. Our findings demonstrate that mouse ES cells generate skeletal myocytes effectively upon treatment with rexinoid at the early stage of differentiation and that on a molecular level, rexinoid-enhanced myogenesis simulates the sequential events observed in vivo. Moreover, RXR-mediated myogenic conversion requires the function of β-catenin but not RAR. Our studies establish the feasibility of applying the RXR agonist in cell-based therapies to treat muscle-related diseases. The aptitude of mouse ES cells to generate skeletal myocytes following rexinoid induction also provides a model system to study the convergence of different signaling pathways in myogenesis.