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INTRODUCTION: A three-pronged approach to acne treatment combining an antibiotic, antimicrobial, and retinoid may be more efficacious than single/double treatments while potentially reducing antibiotic resistance. This study evaluated the efficacy and safety of the first fixed-dose, triple-combination topical acne product, clindamycin 1.2%/adapalene 0.15%/benzoyl peroxide (BPO) 3.1% gel (CAB) using pooled phase 3 data. METHODS: In two identical phase 3 (N = 183; N = 180), double-blind, 12-week studies, participants aged ≥ 9 years with moderate-to-severe acne were randomized 2:1 to receive once-daily CAB or vehicle gel. Endpoints included ≥ 2-grade reduction from baseline in Evaluators Global Severity Score and clear/almost clear skin (treatment success) and least-squares mean percent change from baseline in acne lesion counts. Treatment-emergent adverse events (TEAEs) and cutaneous safety/tolerability were evaluated. RESULTS: At week 12, 50.0% of participants achieved treatment success with CAB versus 22.6% with vehicle gel (P  70% reductions in inflammatory and noninflammatory lesions at week 12 (77.9% and 73.0%, respectively), which were significantly greater than vehicle (57.9% and 48.2%; P

Patients with BRAF‐mutated colorectal cancer (BRAFV600E CRC) are currently treated with a combination of BRAF inhibitor and anti‐EGFR antibody with or without MEK inhibitor. A fundamental problem in treating patients with BRAFV600E CRC is intrinsic and/or acquired resistance to this combination therapy. By screening 78 compounds, we identified tretinoin, a retinoid, as a compound that synergistically enhances the antiproliferative effect of a combination of BRAF inhibition and MEK inhibition with or without EGFR inhibition on BRAFV600E CRC cells. This synergistic effect was also exerted by other retinoids. Tretinoin, added to BRAF inhibitor and MEK inhibitor, upregulated PARP, BAK, and p‐H2AX. When either RARα or RXRα was silenced, the increase in cleaved PARP expression by the addition of TRE to ENC/BIN or ENC/BIN/CET was canceled. Our results suggest that the mechanism of the synergistic antiproliferative effect involves modulation of the Bcl‐2 family and the DNA damage response that affects apoptotic pathways, and this synergistic effect is induced by RARα‐ or RXRα‐mediated apoptosis. Tretinoin also enhanced the antitumor effect of a combination of the BRAF inhibitor and anti‐EGFR antibody with or without MEK inhibitor in a BRAFV600E CRC xenograft mouse model. Our data provide a rationale for developing retinoids as a new combination agent to overcome resistance to the combination therapy for patients with BRAFV600E CRC. [ABSTRACT FROM AUTHOR]

ABSTRACT Background Aims Methods Results Conclusions Many people are interested in addressing visible signs of aging with non‐invasive cosmetic treatments. Development of effective topical products will provide options to delay or support cosmetic procedures.This study assessed and compared the efficacy and tolerance of a topical product used over the course of 16 weeks to a single ablative laser treatment on women with moderate global photodamage on the face.Subjects in Cell 1 (Laser Cell) were treated over the entire face with a fractional CO2 laser system. Subjects in Cell 2 (Topical Serum Cell) were treated with a topical serum containing hydroxypinacolone retinoate and peptides over the entire face, twice per day for 16 weeks. The study was composed of 71 women, with 29 in the Laser Cell (mean age 56.2) and 42 in the Topical Serum Cell (mean age 55.0), between 40 and 65 years old. Expert grading was used to determine efficacy parameters.Participants in the Topical Serum Cell achieved more significant improvement (p < 0.05) in Marionette lines, fine lines (global face), wrinkles (global face), wrinkles (crow's feet), nasolabial folds, texture, smoothness (tactile), global hyperpigmentation, lift, and photodamage compared to participants in the Laser Cell. Participants in the Topical Serum Cell achieved parity in the look of fine lines (crow's feet), forehead lines, glabella, firmness/bounce (tactile), skin tone evenness, radiance.While no statistically significant differences in tolerability were observed, treatment with the topical cosmetic product achieved parity or statistically better improvement in parameters compared to laser treatment at 16 weeks. [ABSTRACT FROM AUTHOR]

Isotretinoin is an oral medication commonly utilized to treat severe acne. It belongs to the class of retinoids and is a synthetic form of vitamin A. Possible changes in bone tissue associated with the systemic administration of Isotretinoin for long periods and in high doses, such as hypercalcemia, osteopenia, diffuse hyperostosis, or even skeletal deformities, are reported in scientific studies. The objective of this literature review was to analyze the available scientific literature on the systemic administration of Isotretinoin and its effects on bone tissue. To this end, articles that demonstrate effects of Isotretinoin on bone metabolism, bone mineral density, bone formation, and resorption, in addition to possible changes generated in this tissue were considered valid for inclusion in this literature review. The search for articles that fit the premise of this work was carried out in the PubMed/MEDLINE database. In a preliminary search, 85 articles were obtained; after in-depth investigation and checking of the inclusion and exclusion criteria, 21 articles were selected, with 17 articles reporting the effect of systemic administration of Isotretinoin in humans and four articles analyzing the effect generated by this substance systemically administrated in animals, more specifically in rats. After analyzing the selected articles, it was possible to observe several reports on hyperostosis or even changes in the formation of bone structures in human patients. Concerning animals, the largest number of studies addressed the changes caused in the formation or development of bone structures by the systemic administration of Isotretinoin. From the current analyses, and given the wide use of Isotretinoin, it is necessary to know its viability and influence on tissues. Its clinical efficacy seems to overcome any of the skeletal side effects observed; however, more studies are necessary to properly evaluate and prove the effects generated on bone tissues as well as other structures.

Amyotrophic lateral sclerosis (ALS) is the most common motor neuron disease worldwide and is characterized by progressive muscle atrophy. There are currently two approved treatments, but they only relieve symptoms briefly and do not cure the disease. The main hindrance to research is the complex cause of ALS, with its pathogenesis not yet fully elucidated. Retinoids (vitamin A derivatives) appear to be essential in neuronal cells and have been implicated in ALS pathogenesis. This study explores 4-[2-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydroquinoxalin-2-yl)ethylnyl]benzoic acid (Ellorarxine, or DC645 or NVG0645), a leading synthetic retinoic acid, discussing its pharmacological mechanisms, neuroprotective properties, and relevance to ALS. The potential therapeutic effect of Ellorarxine was analyzed in vitro using the WT and SOD1G93A NSC-34 cell model of ALS at an administered concentration of 0.3–30 nM. Histological, functional, and biochemical analyses were performed. Elorarxine significantly increased MAP2 expression and neurite length, increased AMPA receptor GluA2 expression and raised intracellular Ca2+ baseline, increased level of excitability, and reduced Ca2+ spike during depolarization in neurites. Ellorarxine also displayed both antioxidant and anti-inflammatory effects. Overall, these results suggest Ellorarxine shows relevance and promise as a novel therapeutic strategy for treatment of ALS. [ABSTRACT FROM AUTHOR]

Introduction: An expert panel of Canadian dermatologists was assembled to develop consensus statements regarding the current landscape of topical therapies for plaque psoriasis and the place in therapy of the recently approved fixed-dose combination halobetasol propionate (HP)/tazarotene (TAZ) lotion (HP/TAZ) in the treatment algorithm for plaque psoriasis. Method: A modified nominal group technique, which combined both independent and group input from the expert panel, was used to develop the consensus statements. The expert panel completed surveys to elicit their independent views on the current landscape of topical therapies for plaque psoriasis in Canada. The first expert panel session was held to discuss the existing body of literature and develop draft consensus statements about topical therapies and the place in therapy of HP/TAZ. Independent feedback on the draft consensus statements was solicited from expert panel members prior to another expert panel session where the amended consensus statements were further discussed, edited and, finally, voted on. Results: The expert panel reached consensus on 20 statements. Conclusion: Expert panel members agreed, based on the existing body of literature, that there is a place in therapy for HP/TAZ to address several current unmet treatment needs of patients with plaque psoriasis. Studies have shown that HP/TAZ is an effective and safe first-line treatment for moderate-to-severe plaque psoriasis. Due to its cosmetically pleasing vehicle and once-daily administration, HP/TAZ may improve patient acceptance and treatment adherence. [ABSTRACT FROM AUTHOR]

Abstract Introduction An expert panel of Canadian dermatologists was assembled to develop consensus statements regarding the current landscape of topical therapies for plaque psoriasis and the place in therapy of the recently approved fixed-dose combination halobetasol propionate (HP)/tazarotene (TAZ) lotion (HP/TAZ) in the treatment algorithm for plaque psoriasis. Method A modified nominal group technique, which combined both independent and group input from the expert panel, was used to develop the consensus statements. The expert panel completed surveys to elicit their independent views on the current landscape of topical therapies for plaque psoriasis in Canada. The first expert panel session was held to discuss the existing body of literature and develop draft consensus statements about topical therapies and the place in therapy of HP/TAZ. Independent feedback on the draft consensus statements was solicited from expert panel members prior to another expert panel session where the amended consensus statements were further discussed, edited and, finally, voted on. Results The expert panel reached consensus on 20 statements. Conclusion Expert panel members agreed, based on the existing body of literature, that there is a place in therapy for HP/TAZ to address several current unmet treatment needs of patients with plaque psoriasis. Studies have shown that HP/TAZ is an effective and safe first-line treatment for moderate-to-severe plaque psoriasis. Due to its cosmetically pleasing vehicle and once-daily administration, HP/TAZ may improve patient acceptance and treatment adherence.

Abstract Introduction A three-pronged approach to acne treatment combining an antibiotic, antimicrobial, and retinoid may be more efficacious than single/double treatments while potentially reducing antibiotic resistance. This study evaluated the efficacy and safety of the first fixed-dose, triple-combination topical acne product, clindamycin 1.2%/adapalene 0.15%/benzoyl peroxide (BPO) 3.1% gel (CAB) using pooled phase 3 data. Methods In two identical phase 3 (N = 183; N = 180), double-blind, 12-week studies, participants aged ≥ 9 years with moderate-to-severe acne were randomized 2:1 to receive once-daily CAB or vehicle gel. Endpoints included ≥ 2-grade reduction from baseline in Evaluator’s Global Severity Score and clear/almost clear skin (treatment success) and least-squares mean percent change from baseline in acne lesion counts. Treatment-emergent adverse events (TEAEs) and cutaneous safety/tolerability were evaluated. Results At week 12, 50.0% of participants achieved treatment success with CAB versus 22.6% with vehicle gel (P 70% reductions in inflammatory and noninflammatory lesions at week 12 (77.9% and 73.0%, respectively), which were significantly greater than vehicle (57.9% and 48.2%; P

Isotretinoin is an oral medication commonly utilized to treat severe acne. It belongs to the class of retinoids and is a synthetic form of vitamin A. Possible changes in bone tissue associated with the systemic administration of Isotretinoin for long periods and in high doses, such as hypercalcemia, osteopenia, diffuse hyperostosis, or even skeletal deformities, are reported in scientific studies. The objective of this literature review was to analyze the available scientific literature on the systemic administration of Isotretinoin and its effects on bone tissue. To this end, articles that demonstrate effects of Isotretinoin on bone metabolism, bone mineral density, bone formation, and resorption, in addition to possible changes generated in this tissue were considered valid for inclusion in this literature review. The search for articles that fit the premise of this work was carried out in the PubMed/MEDLINE database. In a preliminary search, 85 articles were obtained; after in-depth investigation and checking of the inclusion and exclusion criteria, 21 articles were selected, with 17 articles reporting the effect of systemic administration of Isotretinoin in humans and four articles analyzing the effect generated by this substance systemically administrated in animals, more specifically in rats. After analyzing the selected articles, it was possible to observe several reports on hyperostosis or even changes in the formation of bone structures in human patients. Concerning animals, the largest number of studies addressed the changes caused in the formation or development of bone structures by the systemic administration of Isotretinoin. From the current analyses, and given the wide use of Isotretinoin, it is necessary to know its viability and influence on tissues. Its clinical efficacy seems to overcome any of the skeletal side effects observed; however, more studies are necessary to properly evaluate and prove the effects generated on bone tissues as well as other structures. [ABSTRACT FROM AUTHOR]

The most common and widespread type of cutaneous T-cell lymphoma is mycosis fungoides (MF), and it has a multiphasic clinical and biological course, with early stages being indolent for many years and later stages being faster and more aggressive. The clinical stage has a significant impact on the management and course of treatment: in the early stages, skin-directed therapies (SDT) plus/or biologic response modifiers (BRM); in the later stages, radiotherapy and/or systemic therapies. Even though national and international societies and groups periodically update their clinical recommendations, there is still no universally accepted approach. This paper reviews and discusses the various SDT and BRM options, either separately or in combination. [ABSTRACT FROM AUTHOR]

The most common and widespread type of cutaneous T-cell lymphoma is mycosis fungoides (MF), and it has a multiphasic clinical and biological course, with early stages being indolent for many years and later stages being faster and more aggressive. The clinical stage has a significant impact on the management and course of treatment: in the early stages, skin-directed therapies (SDT) plus/or biologic response modifiers (BRM); in the later stages, radiotherapy and/or systemic therapies. Even though national and international societies and groups periodically update their clinical recommendations, there is still no universally accepted approach. This paper reviews and discusses the various SDT and BRM options, either separately or in combination.

Abstract Introduction Plants are a source of natural ingredients with retinol-like properties that can deliver anti-aging benefits without the side effects typically associated with retinoid use. We hypothesized that by combining two such analogs, bakuchiol (BAK) and Vigna aconitifolia extract (VAE), with the potent retinoid retinal (RAL), the anti-photoaging potential of RAL could be enhanced without compromising its skin irritation profile. The purpose of this study was to demonstrate that BAK and VAE potentiate the anti-photoaging activity of RAL. Methods Gene expression profiling of full-thickness reconstructed skin was first used to examine the impact of BAK or VAE in combination with RAL on skin biology. Next, the irritative potential of this combination, and its capacity to reverse key signs of photoaging in an ex vivo model was assessed. Finally, a proof-of-concept open label clinical study was performed to evaluate the anti-photoaging capacity and skin compatibility of a cosmetic formulation (tri-retinoid complex; 3RC) containing this complex in combination with other well characterized anti-photoaging ingredients. Results In vitro profiling suggested that combining 0.1% RAL with BAK or VAE potentiates the effect of RAL on keratinocyte differentiation and skin barrier function without affecting its skin irritation profile. When formulated with other anti-photoaging ingredients, such as niacinamide and melatonin, 3RC reversed ultraviolet radiation-induced deficits in structural components of the dermal extracellular matrix, including hyaluronic acid and collagen. In vivo, it led to a reversal of clinical signs of age and photodamage, with statistically significant improvement to skin firmness (+5.6%), skin elasticity (+13.9%), wrinkle count (−43.2%), and skin tone homogeneity (+7.0%), observed within 28 days of once nightly use. Notably, the number of crow’s feet wrinkles was reduced in 100% of subjects. Furthermore, 3RC was very well tolerated. Conclusion These data suggest that 3RC is a highly effective and well-tolerated treatment for photoaging.

Introduction: Plants are a source of natural ingredients with retinol-like properties that can deliver anti-aging benefits without the side effects typically associated with retinoid use. We hypothesized that by combining two such analogs, bakuchiol (BAK) and Vigna aconitifolia extract (VAE), with the potent retinoid retinal (RAL), the anti-photoaging potential of RAL could be enhanced without compromising its skin irritation profile. The purpose of this study was to demonstrate that BAK and VAE potentiate the anti-photoaging activity of RAL. Methods: Gene expression profiling of full-thickness reconstructed skin was first used to examine the impact of BAK or VAE in combination with RAL on skin biology. Next, the irritative potential of this combination, and its capacity to reverse key signs of photoaging in an ex vivo model was assessed. Finally, a proof-of-concept open label clinical study was performed to evaluate the anti-photoaging capacity and skin compatibility of a cosmetic formulation (tri-retinoid complex; 3RC) containing this complex in combination with other well characterized anti-photoaging ingredients. Results: In vitro profiling suggested that combining 0.1% RAL with BAK or VAE potentiates the effect of RAL on keratinocyte differentiation and skin barrier function without affecting its skin irritation profile. When formulated with other anti-photoaging ingredients, such as niacinamide and melatonin, 3RC reversed ultraviolet radiation-induced deficits in structural components of the dermal extracellular matrix, including hyaluronic acid and collagen. In vivo, it led to a reversal of clinical signs of age and photodamage, with statistically significant improvement to skin firmness (+5.6%), skin elasticity (+13.9%), wrinkle count (−43.2%), and skin tone homogeneity (+7.0%), observed within 28 days of once nightly use. Notably, the number of crow's feet wrinkles was reduced in 100% of subjects. Furthermore, 3RC was very well tolerated. Conclusion: These data suggest that 3RC is a highly effective and well-tolerated treatment for photoaging. [ABSTRACT FROM AUTHOR]

Pseudomyxoma peritonei (PMP) refers to a growth disorder characterized by glycoprotein neoplasm in the peritoneum, where mucin oversecretion occurs. The tumors of the appendix region are well associated with PMP; however, ovarian, colon, stomach, pancreas, and urachus tumors have also been linked to PMP. Other mucinous tumors in the pelvis, paracolic gutters, greater omentum, retrohepatic space, and Treitz ligament can be the reason for PMP. Despite being rare and having a slow growth rate, PMP can be lethal without treatment. It is treated with neoadjuvant chemotherapy with the option of cytoreductive surgery and intraperitoneal chemotherapy. In the current study, we hypothesize that there may be novel gentle ways to inhibit or eliminate the mucin. Dr. David Morris has used mucolytics—such as bromelain and N-acetyl cysteine to solubilize mucin. In the present review, we aimed to study the regulation of mucin expression by promoter methylation, and drugs that can inhibit mucin, such as boldine, amiloride, naltrexone, dexamethasone, and retinoid acid receptors antagonist. This review also explored some possible pathways, such as inhibition of Na + , Ca2+ channels and induction of DNA methyltransferase along with inhibition of ten-eleven translocation enzymes, which can be good targets to control mucin. Mucins are strong adhesive molecules that play great roles in clinging to cells or cell to cell. Besides, they have been greatly involved in metastasis and also act as disease markers for cancers. Diagnostic markers may have exclusive roles in disease initiation and progression. Therefore, the present review explores various drugs to control and target mucin in various diseases, specifically cancers.

Longitudinal growth and puberty are the result of a complex interaction of genetic, hormonal, nutritional, and environmental factors. Acne vulgaris is a chronic disease of the pilosebaceous unit that affects 85% of adolescents worldwide. Isotretinoin is a synthetic vitamin A derivative drug effective and is widely employed for the treatment of moderate and severe acne vulgaris. Premature epiphyseal closure has been reported in patients with neuroblastoma treated with high doses of isotretinoin as well as in patients with acne receiving lower doses. Although the mechanisms for these effects are not clear, it has been suggested that isotretinoin may have a negative impact on the GH-IGF-I axis, leading to a reduction in IGF-I and IGFBP3 serum levels. Although many of the isotretinoin adverse effects in pediatric patients are transient, premature epiphyseal closure and bone abnormalities can lead to transient abnormalities and permanent deformities with a negative impact on longitudinal growth and final height. The aim of this study was to review the potential effects of oral isotretinoin on the growth plate and growth during childhood and adolescence.

Topical and systemic retinoids have long been used in the treatment of ichthyoses and other disorders of cornification. Due to the need for long-term use of retinoids for these disorders, often beginning in childhood, numerous clinical concerns must be considered. Systemic retinoids have known side effects involving bone and eye. Additionally, potential psychiatric and cardiovascular effects need to be considered. Contraceptive concerns, as well as the additive cardiovascular and bone effects of systemic retinoid use with hormonal contraception must also be deliberated for patients of childbearing potential. The Pediatric Dermatology Research Alliance (PeDRA) Use of Retinoids in Ichthyosis Work Group was formed to address these issues and to establish best practices regarding the use of retinoids in ichthyoses based on available evidence and expert opinion.

Background: Acne often worsens in transmasculine patients who are on prolonged testosterone therapy. Isotretinoin is an oral retinoid used in the treatment of severe or refractory cases of acne, but it has the potential to cause delayed wound healing. Transmasculine patients may potentially be prescribed treatment for acne with isotretinoin while also planning to undergo chest masculinization surgery. Objective: This scoping review aims to determine whether isotretinoin has a negative impact on postoperative healing in transmasculine patients undergoing chest masculinization surgery. Methods: A scoping review was performed using the PubMed and Ovid databases. A total of 16 publications were selected for inclusion. Results: Acne tends to peak in transmasculine patients six months after initiation of testosterone treatment. Severe cases can be treated with isotretinoin; however, acne may recur once treatment is discontinued, given ongoing hormone therapy. There is little-to-no evidence in the medical literature regarding perioperative use of isotretinoin specifically among transmasculine patients undergoing chest masculinization surgery. In general, however, recent studies have found no evidence of increased hypertrophic scars or keloids in patients taking isotretinoin. Conclusion: Further studies are required to strengthen the current evidence that suggests that isotretinoin does not need to be discontinued before or after incisional or excisional surgeries, including chest masculinization surgery in transmasculine patients. [ABSTRACT FROM AUTHOR]

Abstract is missing (Short communication)

Background Excessive sebum production is a factor in acne development. Tazarotene 0.045% lotion has demonstrated reductions in acne lesions and acne-induced sequelae. Objective Evaluate efficacy, changes in skin oiliness, and safety with tazarotene 0.045% lotion in participants with moderate-to-severe acne and oily skin. Methods In two phase 3, double-blind, 12-week studies (NCT03168321; NCT03168334), participants aged ≥ 9 years with moderate-to-severe acne were randomized 1:1 to once-daily tazarotene 0.045% lotion or vehicle lotion (N = 1614). This pooled, post hoc analysis included only participants self-categorized with oily skin at baseline on the Acne-Specific Quality of Life questionnaire item 19 (scores: 0 [extremely oily] to 6 [not at all oily]). Inflammatory/noninflammatory lesion counts, treatment success, skin oiliness, treatment-emergent adverse events (TEAEs), and cutaneous safety/tolerability were evaluated. Results In all participants with oily skin (n = 793), tazarotene provided greater reductions in inflammatory/noninflammatory lesions (p

OBJECTIVE: The condition of the skin can vary due to weather fluctuations. Therefore, this post-hoc analysis evaluated efficacy and safety of tazarotene 0.045% lotion in warmer versus colder months. METHODS: In two Phase III, double-blind, 12-week studies, participants aged nine years or older with moderate-to- severe acne were randomized 1:1 to once-daily tazarotene or vehicle lotion. The pooled population (N=1,614) was stratified by randomization date (warmer=May to September; colder=October to April). Evaluations included inflammatory/noninflammatory lesion counts, treatment success, adverse events, and safety/tolerability. RESULTS: Tazarotene 0.045% lotion was similarly efficacious over colder and warmer months. Compared with vehicle, tazarotene demonstrated significantly greater least-squares mean absolute reductions from baseline to Week 12 in inflammatory (colder/warmer tazarotene vs. vehicle: -16.6/-15.8 vs. -13.2/-12.9) and noninflammatory lesions (-23.2/-22.6 vs. -17.5/-15.1); treatment success rates were also significantly higher (30.1/30.8% vs. 18.2/17.6%) (P<0.001, all). No strong seasonal trends in safety were observed, though tazarotene led to slightly more discontinuations (3.4% vs. 1.9%) and related adverse events (12.0% vs. 10.3%) in colder versus warmer months. Transient increases in scaling, erythema, and itching at Weeks 2 to 8 of tazarotene treatment were slightly higher in colder versus warmer months but returned to baseline/improved by Week 12. LIMITATIONS: Geographical variation across study sites can lead to varying temperatures and humidity within the same months. CONCLUSION: Tazarotene 0.045% lotion was efficacious and well tolerated for acne treatment, regardless of season. Year-round tolerability of tazarotene 0.045% lotion may be due to its lower tazarotene concentration and polymeric emulsion technology, which simultaneously delivers moisturizers/humectants/emollients to skin. [ABSTRACT FROM AUTHOR]

Simple Summary: In the realm of cancer treatment and prevention, the application of retinoids has led to unparalleled successes and humbling disappointments; all-trans retinoic acid (ATRA) has transformed APL (acute promyelocytic leukemia) into an eminently curable disease but has demonstrated little efficacy in acute myeloid leukemia (AML) more broadly. As a cancer prevention strategy, vitamin A supplementation was ineffective and appeared to increase lung cancer incidence, underscoring the complex relationship between retinoic acid signaling and carcinogenesis. This review aims to provide a survey of our current understanding of retinoic acid homeostasis and signaling, to reflect on prior successes and failures to deploy retinoids in the treatment and prevention of cancer, and to explore the unfulfilled potential of retinoids in cancer. New biological insights relating to the regulation of retinoid homeostasis and the discovery of biomarkers of retinoid sensitivity in subsets of non-APL AML have revived enthusiasm for the therapeutic potential of synthetic retinoids, and thus warrant a reacquaintance with retinoid biology. Since the introduction of all-trans retinoic acid (ATRA), acute promyelocytic leukemia (APL) has become a highly curable malignancy, especially in combination with arsenic trioxide (ATO). ATRA's success has deepened our understanding of the role of the RARα pathway in normal hematopoiesis and leukemogenesis, and it has influenced a generation of cancer drug development. Retinoids have also demonstrated some efficacy in a handful of other disease entities, including as a maintenance therapy for neuroblastoma and in the treatment of cutaneous T-cell lymphomas; nevertheless, the promise of retinoids as a differentiating therapy in acute myeloid leukemia (AML) more broadly, and as a cancer preventative, have largely gone unfulfilled. Recent research into the mechanisms of ATRA resistance and the biomarkers of RARα pathway dysregulation in AML have reinvigorated efforts to successfully deploy retinoid therapy in a broader subset of myeloid malignancies. Recent studies have demonstrated that the bone marrow environment is highly protected from exogenous ATRA via local homeostasis controlled by stromal cells expressing CYP26, a key enzyme responsible for ATRA inactivation. Synthetic CYP26-resistant retinoids such as tamibarotene bypass this stromal protection and have shown superior anti-leukemic effects. Furthermore, recent super-enhancer (SE) analysis has identified a novel AML subgroup characterized by high expression of RARα through strong SE levels in the gene locus and increased sensitivity to tamibarotene. Combined with a hypomethylating agent, synthetic retinoids have shown synergistic anti-leukemic effects in non-APL AML preclinical models and are now being studied in phase II and III clinical trials. [ABSTRACT FROM AUTHOR]

Background: Aging is responsible for the majority of skin and soft tissue remolding in humans. Retinol and its derivatives or retinoids effectively intervene skin aging process. Nevertheless, retinoids usually induce skin intolerance, especially among the Chinese, and thus, their application to prevent skin aging is yet to be well accepted. The study of optimal composition and concentration of retinoids is necessary to offer strong antiaging efficacies with minimum irritations. Therefore, a better understanding of retinol and its derivatives is acutely needed to develop strategies to combat skin aging. Objective: In this study, we aimed to determine the optimal ratio of two retinol derivatives—hydroxypinacolone retinoate (HPR) and retinyl propionate (RP) in terms of dermal remodeling and skin aging prevention—and to investigate their synergistic antiaging effects both in vitro and in vivo. Methods: An in vitro human foreskin fibroblast (HFF‐1) cell model was established to evaluate the cell viability of HPR and/or RP treatment. In addition, the antiaging and retinol receptor genes expressions in HFF‐1 cells cotreated with HPR and RP were quantified. The in vivo adverse reaction evaluation of skincare serums containing various levels of retinol or the optimal HPR and RP combination termed Gravi‐A was performed by 24 h patch tests in 33 subjects prior to the clinical research. Last but not the least, clinical research with 42 Chinese urban women was conducted to assess the in vivo antiaging efficacy of the skincare serum containing this optimal retinoid combination. Results: The combination of HPR and RP at the weight ratio of 5:9 was shown to achieve the optimal in vitro antiaging performance. Coadministration of 5 μg/mL HPR and 9 μg/mL RP to HFF‐1 cells promoted their proliferation at 24 h and synergistically enhanced the expressions of type IV collagen, CRBP‐I, and RARB genes. In addition, the skincare serum containing HPR and RP combination at 5:9 weight ratio demonstrated superior in vivo anti‐wrinkle and skin elasticity improvement benefits without any adverse reactions, while retinol in the same concentration exerted much higher adverse effect. Skin wrinkles, skin smoothness, TEWL, skin elasticity R2 and R5 were improved by 8.3%, 11.9%, 25.7%, 14.5%, and 22.6%, respectively, after 8‐week use. Conclusion: Our results indicated the advanced antiaging effect of HPR and RP combination both in vitro and in vivo. In addition, little adverse effect was observed in this study, in comparison with retinol. This combination named as Gravi‐A is a potential therapeutic strategy to prevent skin aging, especially for Chinese women. [ABSTRACT FROM AUTHOR]

Introduction/Background: Acitretin is a second-generation systemic retinoid. Its clinical applications are virtually exclusively limited to dermatology. It has anti-inflammatory, antiproliferative, and antikeratinizing effects. However, there is a lack of articles summarizing the relevant literature in a systemic way. Methods: A PubMed search was performed using keywords such as “retinoids,” “acitretin,” “etretinate,” and “retinoid embryopathy” to identify relevant original articles, case series, and case reports. Results: The most commonly used application of acitretin, a second-generation systemic retinoid is in the treatment of psoriasis. It has been used in various other dermatological disorders (keratoderma, ichthyosis, pityriasis rubra pilaris, and lichen planus) as a stand-alone therapy or may be combined with other topical and systemic agents. As the drug is not an immunosuppressive agent, hence can be given safely to patients suffering from human immunodeficiency virus and taking highly active antiretroviral therapy. The drug can be given safely in the pediatric as well as the adult population. Although adverse effects are common usually minor and self-limiting and can be managed easily without stopping the drug. The main side effects of the drug include teratogenicity, hepatotoxicity, and hyperlipidemia which should be monitored regularly. It should be avoided or used cautiously in patients taking methotrexate, cyclosporine, and corticosteroids. Conclusions: This article has discussed various uses of acitretin in dermatology, its side effect profile, indication, contraindication, and drug interactions. The drug can be administered safely and successfully with the right patient selection, progressive dose increase, careful monitoring, and appropriate patient counseling.

Dietary deficiencies in zinc (Zn) and vitamin A (VA) are among the leading micronutrient deficiencies globally and previous research has proposed a notable interaction between Zn and VA physiological status. This study aimed to assess the effects of zinc and vitamin A (isolated and combined) on intestinal functionality and morphology, and the gut microbiome (Gallus gallus). The study included nine treatment groups (n~11)—no-injection (NI); H2O; 0.5% oil; normal zinc (40 mg/kg ZnSO4) (ZN); low zinc (20 mg/kg) (ZL); normal retinoid (1500 IU/kg retinyl palmitate) (RN); low retinoid (100 IU/kg) (RL); normal zinc and retinoid (40 mg/kg; 1500 IU/kg) (ZNRN); low zinc and retinoid (ZLRL) (20 mg/kg; 100 IU/kg). Samples were injected into the amniotic fluid of the fertile broiler eggs. Tissue samples were collected upon hatch to target biomarkers. ZLRL reduced ZIP4 gene expression and upregulated ZnT1 gene expression (p < 0.05). Duodenal surface area increased the greatest in RL compared to RN (p < 0.01), and ZLRL compared to ZNRN (p < 0.05). All nutrient treatments yielded shorter crypt depths (p < 0.01). Compared to the oil control, ZLRL and ZNRN reduced (p < 0.05) the cecal abundance of Bifidobacterium and Clostridium genera (p < 0.05). These results suggest a potentially improved intestinal epithelium proceeding with Zn and VA intra-amniotic administration. Intestinal functionality and gut bacteria were modulated. Further research should characterize long-term responses and the microbiome profile. [ABSTRACT FROM AUTHOR]

Longitudinal growth and puberty are the result of a complex interaction of genetic, hormonal, nutritional, and environmental factors. Acne vulgaris is a chronic disease of the pilosebaceous unit that affects 85% of adolescents worldwide. Isotretinoin is a synthetic vitamin A derivative drug effective and is widely employed for the treatment of moderate and severe acne vulgaris. Premature epiphyseal closure has been reported in patients with neuroblastoma treated with high doses of isotretinoin as well as in patients with acne receiving lower doses. Although the mechanisms for these effects are not clear, it has been suggested that isotretinoin may have a negative impact on the GH-IGF-I axis, leading to a reduction in IGF-I and IGFBP3 serum levels. Although many of the isotretinoin adverse effects in pediatric patients are transient, premature epiphyseal closure and bone abnormalities can lead to transient abnormalities and permanent deformities with a negative impact on longitudinal growth and final height. The aim of this study was to review the potential effects of oral isotretinoin on the growth plate and growth during childhood and adolescence. [ABSTRACT FROM AUTHOR]

Retinoids are defined as molecules that bind to and activate retinoic acid receptors to influence the proliferation and differentiation of cells. Topical retinoids have evolved over the past several decades, being used in multiple dermatological conditions. This review aims to differentiate between synthetic and natural retinoids, discuss the pharmacology behind topical retinoids, highlight clinical applications, and categorize all the commercially available agents, including combination products. Understanding retinoid afinities for unique receptor subtypes can impact clinical decisions, resulting in optimizing treatment and enhancing patient adherence. [ABSTRACT FROM AUTHOR]

The variable composition of the chromophore-binding pocket in visual receptors is essential for vision. The visual phototransduction starts with the cis-trans isomerization of the retinal chromophore upon absorption of photons. Despite sharing the common 11-cis-retinal chromophore, rod and cone photoreceptors possess distinct photochemical properties. Thus, a detailed molecular characterization of the chromophore-binding pocket of these receptors is critical to understanding the differences in the photochemistry of vision between rods and cones. Unlike for rhodopsin (Rh), the crystal structures of cone opsins remain to be determined. To obtain insights into the specific chromophore-protein interactions that govern spectral tuning in human visual pigments, here we harnessed the unique binding properties of 11-cis-6-membered-ring-retinal (11-cis-6mr-retinal) with human blue, green, and red cone opsins. To unravel the specificity of the chromophore-binding pocket of cone opsins, we applied 11-cis-6mr-retinal analog-binding analyses to human blue, green, and red cone opsins. Our results revealed that among the three cone opsins, only blue cone opsin can accommodate the 11-cis-6mr-retinal in its chromophore-binding pocket, resulting in the formation of a synthetic blue pigment (B6mr) that absorbs visible light. A combination of primary sequence alignment, molecular modeling, and mutagenesis experiments revealed the specific amino acid residue 6.48 (Tyr-262 in blue cone opsins and Trp-281 in green and red cone opsins) as a selectivity filter in human cone opsins. Altogether, the results of our study uncover the molecular basis underlying the binding selectivity of 11-cis-6mr-retinal to the cone opsins.

OBJECTIVE: The fixed-dose corticosteroid/retinoid combination halobetasol propionate (0.01%) and tazarotene (0.045%) lotion (HP/TAZ) is approved for topical treatment of plaque psoriasis in adults. In addition to its current indication for plaque psoriasis, a growing body of clinical data suggests that HP/TAZ may be a beneficial therapy for palmoplantar and scalp psoriasis. Here, we discuss the efficacy and safety of HP/TAZ in various psoriatic phenotypes and related conditions. METHODS: Three studies (one post-hoc analysis, two open-label reports) of HP/TAZ were identified for this discussion. RESULTS: A post-hoc analysis demonstrated that once-daily HP/TAZ was associated with sustained efficacy and clinically meaningful quality-of-life improvements in participants with psoriatic disease who had low quality of life and 3% to 5% affected body surface area at baseline. In open-label reports, HP/TAZ was associated with improvement in scalp psoriasis measures, as well as quality of life. Additionally, HP/TAZ was efficacious in patients with palmoplantar psoriasis and in one report of a patient with palmoplantar pustulosis. LIMITATIONS: Limitations include the small sample sizes of open-label reports of HP/TAZ; larger studies are needed to confirm findings. CONCLUSION: Taken together, this evidence suggests that HP/TAZ may address unmet needs in psoriatic disease as a therapy for patients with all levels of psoriasis severity who experience daily challenges associated with their disease and that it may be a candidate for treating a variety of forms of psoriasis. [ABSTRACT FROM AUTHOR]

Excessive sebum production is a factor in acne development. Tazarotene 0.045% lotion has demonstrated reductions in acne lesions and acne-induced sequelae. Evaluate efficacy, changes in skin oiliness, and safety with tazarotene 0.045% lotion in participants with moderate-to-severe acne and oily skin. In two phase 3, double-blind, 12-week studies (NCT03168321; NCT03168334), participants aged ≥ 9 years with moderate-to-severe acne were randomized 1:1 to once-daily tazarotene 0.045% lotion or vehicle lotion (N = 1614). This pooled, post hoc analysis included only participants self-categorized with oily skin at baseline on the Acne-Specific Quality of Life questionnaire item 19 (scores: 0 [extremely oily] to 6 [not at all oily]). Inflammatory/noninflammatory lesion counts, treatment success, skin oiliness, treatment-emergent adverse events (TEAEs), and cutaneous safety/tolerability were evaluated. In all participants with oily skin (n = 793), tazarotene provided greater reductions in inflammatory/noninflammatory lesions (p < 0.001, both) and greater treatment success rates versus vehicle (p < 0.01) at week 12. Over two-thirds of polymeric lotion-treated participants had subjective skin oiliness reductions by week 12, with around a third reporting 'low/not' oily skin. Tazarotene TEAE rates were similar to the overall population. Once-daily treatment with tazarotene 0.045% polymeric emulsion lotion may help improve patient-perceived skin oiliness in those with moderate-to-severe acne. [ABSTRACT FROM AUTHOR]

Introduction/Background: Acitretin is a second-generation systemic retinoid. Its clinical applications are virtually exclusively limited to dermatology. It has anti-inflammatory, antiproliferative, and antikeratinizing effects. However, there is a lack of articles summarizing the relevant literature in a systemic way. Methods: A PubMed search was performed using keywords such as "retinoids," "acitretin," "etretinate," and "retinoid embryopathy" to identify relevant original articles, case series, and case reports. Results: The most commonly used application of acitretin, a second-generation systemic retinoid is in the treatment of psoriasis. It has been used in various other dermatological disorders (keratoderma, ichthyosis, pityriasis rubra pilaris, and lichen planus) as a stand-alone therapy or may be combined with other topical and systemic agents. As the drug is not an immunosuppressive agent, hence can be given safely to patients suffering from human immunodeficiency virus and taking highly active antiretroviral therapy. The drug can be given safely in the pediatric as well as the adult population. Although adverse effects are common usually minor and self-limiting and can be managed easily without stopping the drug. The main side effects of the drug include teratogenicity, hepatotoxicity, and hyperlipidemia which should be monitored regularly. It should be avoided or used cautiously in patients taking methotrexate, cyclosporine, and corticosteroids. Conclusions: This article has discussed various uses of acitretin in dermatology, its side effect profile, indication, contraindication, and drug interactions. The drug can be administered safely and successfully with the right patient selection, progressive dose increase, careful monitoring, and appropriate patient counseling. [ABSTRACT FROM AUTHOR]

Bexarotene is an FDA-approved drug for the treatment of cutaneous T-cell lymphoma (CTCL); however, its use provokes or disrupts other retinoid-X-receptor (RXR)-dependent nuclear receptor pathways and thereby incites side effects including hypothyroidism and raised triglycerides. Two novel bexarotene analogs, as well as three unique CD3254 analogs and thirteen novel NEt-TMN analogs, were synthesized and characterized for their ability to induce RXR agonism in comparison to bexarotene (1). Several analogs in all three groups possessed an isochroman ring substitution for the bexarotene aliphatic group. Analogs were modeled for RXR binding affinity, and EC50 as well as IC50 values were established for all analogs in a KMT2A-MLLT3 leukemia cell line. All analogs were assessed for liver-X-receptor (LXR) activity in an LXRE system to gauge the potential for the compounds to provoke raised triglycerides by increasing LXR activity, as well as to drive LXRE-mediated transcription of brain ApoE expression as a marker for potential therapeutic use in neurodegenerative disorders. Preliminary results suggest these compounds display a broad spectrum of off-target activities. However, many of the novel compounds were observed to be more potent than 1. While some RXR agonists cross-signal the retinoic acid receptor (RAR), many of the rexinoids in this work displayed reduced RAR activity. The isochroman group did not appear to substantially reduce RXR activity on its own. The results of this study reveal that modifying potent, selective rexinoids like bexarotene, CD3254, and NEt-TMN can provide rexinoids with increased RXR selectivity, decreased potential for cross-signaling, and improved anti-proliferative characteristics in leukemia models compared to 1. [ABSTRACT FROM AUTHOR]

Administration of systemic retinoids such as acitretin has not been approved yet for pediatric patients. An adverse event of retinoid-therapy that occurs with lower prevalence in children than in adults is hyperlipidemia. This might be based on the lack of comorbidities in young patients, but must not be neglected. Especially for the development of the human brain up to young adulthood, dysbalance of lipids might be deleterious. Here, we provide for the first time an in-depth analysis of the influence of subchronic acitretin-administration on lipid composition of brain parenchyma of young wild type mice. For comparison and to evaluate the systemic effect of the treatment, liver lipids were analogously investigated. As expected, triglycerides increased in liver as well as in brain and a non-significant increase in cholesterol was observed. However, specifically brain showed an increase in lyso-phosphatidylcholine and carnitine as well as in sphingomyelin. Group analysis of lipid classes revealed no statistical effects, while single species were tissue-dependently changed: effects in brain were in general more subtly as compared to those in liver regarding the mere number of changed lipid species. Thus, while the overall impact of acitretin seems comparably small regarding brain, the change in individual species and their role in brain development and maturation has to be considered. [ABSTRACT FROM AUTHOR]

Acne vulgaris, caused by pathophysiological processes at the pilosebaceous unit, is among the most common chronic dermatological disorders. Acne sequelae, including scarring and dyspigmentation, are common, and are often more distressing to patients than active acne lesions, reinforcing the importance of prevention and effective treatment. Trifarotene, a novel fourth generation retinoid selective for retinoid acid receptor gamma, is approved for the management of moderate-to-severe facial and truncal acne, with recent data supporting its efficacy in acne-induced hyperpigmentation. The purpose of this paper is to review treatment modalities for post-inflammatory hyperpigmentation and present trifarotene as a novel, evidence-based topical option., Competing Interests: Monica K. Li is a consultant and speaker for Galderma Canada. Santina Conte has no relevant conflicts of interest.

Patients with BRAF-mutated colorectal cancer (BRAF V600E CRC) are currently treated with a combination of BRAF inhibitor and anti-EGFR antibody with or without MEK inhibitor. A fundamental problem in treating patients with BRAF V600E CRC is intrinsic and/or acquired resistance to this combination therapy. By screening 78 compounds, we identified tretinoin, a retinoid, as a compound that synergistically enhances the antiproliferative effect of a combination of BRAF inhibition and MEK inhibition with or without EGFR inhibition on BRAF V600E CRC cells. This synergistic effect was also exerted by other retinoids. Tretinoin, added to BRAF inhibitor and MEK inhibitor, upregulated PARP, BAK, and p-H2AX. When either RARα or RXRα was silenced, the increase in cleaved PARP expression by the addition of TRE to ENC/BIN or ENC/BIN/CET was canceled. Our results suggest that the mechanism of the synergistic antiproliferative effect involves modulation of the Bcl-2 family and the DNA damage response that affects apoptotic pathways, and this synergistic effect is induced by RARα- or RXRα-mediated apoptosis. Tretinoin also enhanced the antitumor effect of a combination of the BRAF inhibitor and anti-EGFR antibody with or without MEK inhibitor in a BRAF V600E CRC xenograft mouse model. Our data provide a rationale for developing retinoids as a new combination agent to overcome resistance to the combination therapy for patients with BRAF V600E CRC., (© 2024 The Author(s). Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.)

The clinical appearance of acne vulgaris (AV) and the response to therapeutic agents may vary in people with skin of color (SoC) compared with those with lighter skin types. Given the heightened potential for postinflammatory hyperpigmentation and keloid development, effective and timely AV treatment in patients with SoC is especially important. However, these patients are frequently underrepresented in clinical trials, and SoC photographs are generally underrepresented in dermatology. Trifarotene 0.005% cream is a retinoid approved for the once-daily topical treatment of AV, and was studied in large-scale clinical trials that assessed the treatment of AV on both the face and trunk. For severe AV, a topical retinoid may be used in combination with an oral antibiotic, such as doxycycline. Five subjects covering Fitzpatrick skin phototypes III, IV, V, and VI were selected from two larger studies to visually demonstrate treatment of clinically diagnosed AV with trifarotene 0.005% cream. Two subjects received 24 weeks of treatment with trifarotene 0.005% cream for moderate AV on the face and trunk, while three subjects received 12 weeks of treatment with trifarotene 0.005% cream in association with 120 mg oral doxycycline with modified polymer coating for severe facial AV. This case series supports the favorable efficacy and safety of facial and truncal AV treatment with trifarotene 0.005% cream, with or without oral doxycycline, in subjects with SoC (phototypes III–VI). [ABSTRACT FROM AUTHOR]

Abstract Background Recurrent hepatocellular carcinoma (HCC) shows strong resistance to sorafenib, and the tumor-repopulating cells (TRCs) with cancer stem cell-like properties are considered a driver for its high recurrent rate and drug resistance. Methods Suppression of TRCs may thus be an effective therapeutic strategy for treating this fatal disease. We evaluated the pharmacology and mechanism of sulfarotene, a new type of synthetic retinoid, on the cancer stem cell-like properties of HCC TRCs, and assessed its preclinical efficacy in models of HCC patient-derived xenografts (PDXs). Results Sulfarotene selectively inhibited the growth of HCC TRCs in vitro and significantly deterred TRC-mediated tumor formation and lung metastasis in vivo without apparent toxicity, with an IC50 superior to that of acyclic retinoid and sorafenib, to which the recurrent HCC exhibits significant resistance at advanced stage. Sulfarotene promoted the expression and activation of RARα, which down-regulated SOS2, a key signal mediator associated with RAS activation and signal transduction involved in multiple downstream pathways. Moreover, sulfarotene selectively inhibited tumorigenesis of HCC PDXs with high expression for SOS2. Conclusions Our study identified sulfarotene as a selective inhibitor for the TRCs of HCC, which targets a novel RARα-SOS2-RAS signal nexus, shedding light on a new, promising strategy of target therapy for advanced liver cancer.

Caitlin M Brumfiel,1 Meera H Patel,2 Katheryn A Bell,1 Michael A Cardis3 1Georgetown University School of Medicine, Washington, DC, USA; 2Creighton University School of Medicine, Phoenix Regional Campus, Phoenix, AZ, USA; 3MedStar Washington Hospital Center/Georgetown University Hospital Department of Dermatology, Washington, DC, USACorrespondence: Caitlin M BrumfielGeorgetown University School of Medicine, 3900 Reservoir Road, Washington, DC, 20007, USATel +1 513-260-3948Email cmb373@georgetown.eduAbstract: Acne vulgaris is a common skin condition of the face and trunk that negatively impacts quality of life. Trifarotene is a new first-in-class fourth-generation topical retinoid that has been uniquely studied in the treatment of both facial and truncal acne. Through selective agonism of retinoic acid receptor (RAR)-gamma, the most predominant RAR isotype in the epidermis, trifarotene exerts more targeted, skin-specific effects than earlier generation retinoids. This narrative review summarizes all currently available literature regarding the use of trifarotene in acne vulgaris. We focus on efficacy, safety, and tolerability data and highlight quality of life outcomes and patient-reported satisfaction. Future clinical trials and the clinical applicability of this novel medication in the treatment of acne are also discussed.Keywords: acne vulgaris, trifarotene, retinoid, randomized controlled trials

Phototransduction is initiated when the absorption of light converts the 11-cis-retinal chromophore to its all-trans configuration in both rod and cone vertebrate photoreceptors. To sustain vision, 11-cis-retinal is continuously regenerated from its all-trans conformation through a series of enzymatic steps comprising the visual or retinoid cycle. Abnormalities in this cycle can compromise vision because of the diminished supply of 11-cis-retinal and the accumulation of toxic, constitutively active opsin. As shown previously for rod cells, attenuation of constitutively active opsin can be achieved with the unbleachable analogue, 11-cis-6-membered ring (11-cis-6mr)-retinal, which has therapeutic effects against certain degenerative retinal diseases. However, to discern the molecular mechanisms responsible for this action, pigment regeneration with this locked retinal analogue requires delineation also in cone cells. Here, we compared the regenerative properties of rod and green cone opsins with 11-cis-6mr-retinal and demonstrated that this retinal analogue could regenerate rod pigment but not green cone pigment. Based on structural modeling suggesting that Pro-205 in green cone opsin could prevent entry and binding of 11-cis-6mr-retinal, we initially mutated this residue to Ile, the corresponding residue in rhodopsin. However, this substitution did not enable green cone opsin to regenerate with 11-cis-6mr-retinal. Interestingly, deletion of 16 N-terminal amino acids in green cone opsin partially restored the binding of 11-cis-6mr-retinal. These results and our structural modeling indicate that a more complex binding pathway determines the regeneration of mammalian green cone opsin with chromophore analogues such as 11-cis-6mr-retinal.

Vitamin A is vital to maternal–fetal health and pregnancy outcomes. However, little is known about pregnancy associated changes in maternal vitamin A homeostasis and concentrations of circulating retinol metabolites. The goal of this study was to characterize retinoid concentrations in healthy women (n = 23) during two stages of pregnancy (25–28 weeks gestation and 28–32 weeks gestation) as compared to ≥3 months postpartum. It was hypothesized that plasma retinol, retinol binding protein 4 (RBP4), transthyretin and albumin concentrations would decline during pregnancy and return to baseline by 3 months postpartum. At 25–28 weeks gestation, plasma retinol (−27%), 4-oxo-13-cis-retinoic acid (−34%), and albumin (−22%) concentrations were significantly lower, and all-trans-retinoic acid (+48%) concentrations were significantly higher compared to ≥3 months postpartum in healthy women. In addition, at 28–32 weeks gestation, plasma retinol (−41%), retinol binding protein 4 (RBP4; −17%), transthyretin (TTR; −21%), albumin (−26%), 13-cis-retinoic acid (−23%) and 4-oxo-13-cis-retinoic acid (−48%) concentrations were significantly lower, whereas plasma all-trans-retinoic acid concentrations (+30%) were significantly higher than ≥3 months postpartum. Collectively, the data demonstrates that in healthy pregnancies, retinol plasma concentrations are lower, but all-trans-retinoic acid concentrations are higher than postpartum. [ABSTRACT FROM AUTHOR]

Ligand-activated nuclear receptors (NRs) orchestrate development, growth, and reproduction across all animal lifeforms - the Metazoa - but how NRs evolved remains mysterious. Given the NR ligands including steroids and retinoids are predominantly terpenoids, we asked whether NRs might have evolved from enzymes that catalyze terpene synthesis and metabolism. We provide evidence suggesting that NRs may be related to the terpene synthase (TS) enzyme superfamily. Based on over 10,000 3D structural comparisons, we report that the NR ligand-binding domain and TS enzymes share a conserved core of seven a-helical segments. In addition, the 3D locations of the major ligand-contacting residues are also conserved between the two protein classes. Primary sequence comparisons reveal suggestive similarities specifically between NRs and the subfamily of cis-isoprene transferases, notably with dehydrodolichyl pyrophosphate synthase and its obligate partner, NUS1/NOGOB receptor. Pharmacological overlaps between NRs and TS enzymes add weight to the contention that they share a distant evolutionary origin, and the combined data raise the possibility that a ligand-gated receptor may have arisen from an enzyme antecedent. However, our findings do not formally exclude other interpretations such as convergent evolution, and further analysis will be necessary to confirm the inferred relationship between the two protein classes. [ABSTRACT FROM AUTHOR]

Vitamin A, an essential fat-soluble micronutrient, plays a critical role in the body, by regulating vision, immune responses, and normal development, for instance. Vitamin A deficiency (VAD) is a major cause of xerophthalmia and increases the risk of death from infectious diseases. It is also emerging that prenatal exposure to VAD is associated with disease risks later in life. The overall prevalence of VAD has significantly declined over recent decades; however, the rate of VAD is still high in many low- and mid-income countries and even in high-income countries among specific ethnic/race groups. While VAD occurs when dietary intake is insufficient to meet demands, establishing a strong association between food insecurity and VAD, and vitamin A supplementation is the primary solution to treat VAD, genetic contributions have also been reported to effect serum vitamin A levels. In this review, we discuss genetic variations associated with vitamin A status and vitamin A bioactivity-associated genes, specifically those linked to uptake of the vitamin in the small intestine and its storage in the liver, as well as their potential contribution to vitamin A deficiency risks among different ethnic groups.

Early in the age of modern medicine the consequences of vitamin A deficiency drew attention to the fundamental link between retinoid-dependent homeostatic regulation and malignant hyperproliferative diseases. The term "retinoid" includes a handful of endogenous and a large group of synthetic derivatives of vitamin A. These multifunctional lipid-soluble compounds directly regulate target genes of specific biological functions and critical signaling pathways to orchestrate complex functions from vision to development, metabolism, and inflammation. Many of the retinoid activities on the cellular level have been well characterized and translated to the regulation of processes like differentiation and cell death, which play critical roles in the outcome of malignant transformation of tissues. In fact, retinoid-based differentiation therapy of acute promyelocytic leukemia was one of the first successful examples of molecularly targeted treatment strategies. The selectivity, high receptor binding affinity and the ability of retinoids to directly modulate gene expression programs present a distinct pharmacological opportunity for cancer treatment and prevention. However, to fully exploit their potential, the adverse effects of retinoids must be averted. In this review we provide an overview of the biology of retinoid (activated by nuclear retinoic acid receptors [RARs]) and rexinoid (engaged by nuclear retinoid X receptors [RXRs]) action concluded from a long line of preclinical studies, in relation to normal and transformed states of cells. We will also discuss the past and current uses of retinoids in the treatment of malignancies, the potential of rexinoids in the cancer prevention setting, both as single agents and in combinations.

More than 100 different mutations in the RPE65 gene are associated with inherited retinal degeneration. Although some missense mutations have been shown to abolish isomerase activity of RPE65, the molecular bases leading to loss of function and retinal degeneration remain incompletely understood. Here we show that several missense mutations resulted in significant decrease in expression level of RPE65 in the human retinal pigment epithelium cells. The 26S proteasome non-ATPase regulatory subunit 13, a newly identified negative regulator of RPE65, mediated degradation of mutant RPE65s, which were misfolded and formed aggregates in the cells. Many mutations, including L22P, T101I, and L408P, were mapped on nonactive sites of RPE65. Enzyme activities of these mutant RPE65s were significantly rescued at low temperature, whereas mutant RPE65s with a distinct active site mutation could not be rescued under the same conditions. 4-phenylbutyrate (PBA) displayed a significant synergistic effect on the low temperature-mediated rescue of the mutant RPE65s. Our results suggest that a low temperature eye mask and PBA, a FDA-approved oral medicine, may provide a promising "protein repair therapy" that can enhance the efficacy of gene therapy for delaying retinal degeneration caused by RPE65 mutations.