All-trans retinoic acid suppresses the angiopoietin-Tie2 pathway and inhibits angiogenesis and metastasis in esophageal squamous cell carcinoma

All-trans retinoic acid in hematologic disorders: not just acute promyelocytic leukemia

All-trans retinoic acid (ATRA) plays a role in tissue development, neural function, reproduction, vision, cell growth and differentiation, tumor immunity, and apoptosis. ATRA can act by inducing autophagic signaling, angiogenesis, cell differentiation, apoptosis, and immune function. In the blood system ATRA was first used with great success in acute promyelocytic leukemia (APL), where ATRA differentiated leukemia cells into mature granulocytes. ATRA can play a role not only in APL, but may also play a role in other hematologic diseases such as immune thrombocytopenia (ITP), myelodysplastic syndromes (MDS), non-APL acute myeloid leukemia (AML), aplastic anemia (AA), multiple myeloma (MM), etc., especially by regulating mesenchymal stem cells and regulatory T cells for the treatment of ITP. ATRA can also increase the expression of CD38 expressed by tumor cells, thus improving the efficacy of daratumumab and CD38-CART. In this review, we focus on the mechanism of action of ATRA, its role in various hematologic diseases, drug combinations, and ongoing clinical trials.

All‑trans‑retinoic acid induces RARB‑dependent apoptosis via ROS induction and enhances cisplatin sensitivity by NRF2 downregulation in cholangiocarcinoma cells

All-trans-retinoic acid (ATRA) has been clinically used to treat acute promyelocytic leukemia and is being studied to treat other types of cancer; however, the therapeutic role and mechanism of ATRA against cholangiocarcinoma (CCA) remain unclear. The present study investigated the cytotoxic effect and underlying mechanisms of ATRA on CCA cell lines. Cell viability was evaluated by sulforhodamine B assay. Intracellular reactive oxygen species (ROS) levels were assessed by dihydroethidium assay. Apoptosis analysis was performed by flow cytometry. The pathways of apoptotic cell death induction were examined using enzymatic caspase activity assay. Proteins associated with apoptosis were evaluated by western blotting. The effects on gene expression were analyzed by reverse transcription-quantitative PCR analysis. ATRA induced a concentration- and time-dependent toxicity in CCA cells. Furthermore, when the cytotoxicity of ATRA against retinoic acid receptor (RAR)-deficient cells was assessed, it was revealed that ATRA cytotoxicity was RARB-dependent. Following ATRA treatment, there was a significant accumulation of cellular ROS and ATRA-induced ROS generation led to an increase in the expression levels of apoptosis-inducing proteins and intrinsic apoptosis. Pre-treatment with ROS scavengers could diminish the apoptotic effect of ATRA, suggesting that ROS and mitochondria may have an essential role in the induction of apoptosis. Furthermore, following ATRA treatment, an increase in cellular ROS content was associated with suppressing nuclear factor erythroid 2-related factor 2 (NFE2L2 or NRF2) and NRF2-downstream active genes. ATRA also suppressed cisplatin-induced NRF2 expression, suggesting that the enhancement of cisplatin cytotoxicity by ATRA may be associated with the downregulation of NRF2 signaling. In conclusion, the results of the present study demonstrated that ATRA could be repurposed as an alternative drug for CCA therapy.

Serum Metabolomic Profiling Reveals Biomarkers for Early Detection and Prognosis of Esophageal Squamous Cell Carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most common aggressive malignancies worldwide, particularly in northern China. The absence of specific early symptoms and biomarkers leads to late-stage diagnosis, while early diagnosis and risk stratification are crucial for improving overall prognosis. We performed UPLC-MS/MS on 450 ESCC patients and 588 controls consisting of a discovery group and two validation groups to identify biomarkers for early detection and prognosis. Bioinformatics and clinical statistical methods were used for profiling metabolites and evaluating potential biomarkers. A total of 105 differential metabolites were identified as reliable biomarker candidates for ESCC with the same tendency in three cohorts, mainly including amino acids and fatty acyls. A predictive model of 15 metabolites [all-trans-13,14-dihydroretinol, (±)-myristylcarnitine, (2S,3S)-3-methylphenylalanine, 3-(pyrazol-1-yl)-L-alanine, carnitine C10:1, carnitine C10:1 isomer1, carnitine C14-OH, carnitine C16:2-OH, carnitine C9:1, formononetin, hyodeoxycholic acid, indole-3-carboxylic acid, PysoPE 20:3, PysoPE 20:3(2n isomer1), and resolvin E1] was developed by logistic regression after LASSO and random forest analysis. This model held high predictive accuracies on distinguishing ESCC from controls in the discovery and validation groups (accuracies > 89%). In addition, the levels of four downregulated metabolites [hyodeoxycholic acid, (2S,3S)-3-methylphenylalanine, carnitine C9:1, and indole-3-carboxylic acid] were significantly higher in early cancer than advanced cancer. Furthermore, three independent prognostic markers were identified by multivariate Cox regression analyses with and without clinical indicators: a high level of MG(20:4)isomer and low levels of 9,12-octadecadienoic acid and L-isoleucine correlated with an unfavorable prognosis; the risk score based on these three metabolites was able to stratify patients into low or high risk. Moreover, pathway analysis indicated that retinol metabolism and linoleic acid metabolism were prominent perturbed pathways in ESCC. In conclusion, metabolic profiling revealed that perturbed amino acids and lipid metabolism were crucial metabolic signatures of ESCC. Both panels of diagnostic and prognostic markers showed excellent predictive performances. Targeting retinol and linoleic acid metabolism pathways may be new promising mechanism-based therapeutic approaches. Thus, this study would provide novel insights for the early detection and risk stratification for the clinical management of ESCC and potentially improve the outcomes of ESCC.

All-trans retinoic acid regulating angiopoietins-1 and alleviating extracellular matrix accumulation in interstitial fibrosis rats

All-trans retinoic acid (ATRA) is one of essentially active metabolite of vitamin A, and plays an important role in diverse physiological processes, such as cellular growth and function. Renal interstitial fibrosis (RIF) is a common pathological characteristic of chronic renal disease causing end-stage renal disease currently lacking effective treatment. Low level of Angiopoietins-1 (Angpt-1) is associated with extracellular matrix accumulation and fibrosis diseases. This study was performed to assess the association of ATRA with Angpt-1 in RIF disease. Rats were divided into three groups: group of sham (SHO group), group of unilateral ureteral obstruction group (UUO group), UUO mice administrated daily at the dose of ATRA (ATRA group). Masson-staining was used to detect the histologic lesion. Immunohistochemistry and Western-blot were applied to determine the targeted proteins. RIF score was significantly increased in UUO rats when compared with that of SHO group, and the fibrosis score was notably reduced in ATRA group. Transforming growth factor-β1 (TGF-β1), collagen IV (Col-IV) and fibronectin (FN) expressions in UUO group were significantly up-regulated, whereas Angpt-1 expression was significantly down-regulated compared with the SHO group. ATRA treatment reduced TGF-β1, Col-IV and FN expressions and improved Angpt-1 expression compared with the UUO group. The protein expression of Angpt-1 in kidney tissue of UUO group was negatively correlated with RIF index and protein expressions of Col-IV, FN and TGF-β1. In conclusion, low expression of Angpt-1 was associated with the RIF disease and ATRA treatment can increase the Angpt-1 and alleviate the RIF lesion in UUO rats.

Advances and challenges in the treatment of esophageal cancer

Esophageal cancer (EC) is one of the most common cancers with high morbidity and mortality rates. EC includes two histological subtypes, namely esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC). ESCC primarily occurs in East Asia, whereas EAC occurs in Western countries. The currently available treatment strategies for EC include surgery, chemotherapy, radiation therapy, molecular targeted therapy, and combinations thereof. However, the prognosis remains poor, and the overall five-year survival rate is very low. Therefore, achieving the goal of effective treatment remains challenging. In this review, we discuss the latest developments in chemotherapy and molecular targeted therapy for EC, and comprehensively analyze the application prospects and existing problems of immunotherapy. Collectively, this review aims to provide a better understanding of the currently available drugs through in-depth analysis, promote the development of new therapeutic agents, and eventually improve the treatment outcomes of patients with EC.

All-trans retinoic acid in anticancer therapy: how nanotechnology can enhance its efficacy and resolve its drawbacks

Introduction: All-trans retinoic acid (ATRA, tretinoin) is the main drug used in the treatment of acute promyelocytic leukemia (APL). Despite its impressive activity against APL, the same could not be clinically observed in other types of cancer. Nanotechnology can be a tool to enhance ATRA anticancer efficacy and resolve its drawbacks in APL as well as in other malignancies.Areas covered: This review covers ATRA use in APL and non-APL cancers, the problems that were found in ATRA therapy and how nanoencapsulation can aid to circumvent them. Pre-clinical results obtained with nanoencapsulated ATRA are shown as well as the two ATRA products based on nanotechnology that were clinically tested: ATRA-IV® and Apealea®.Expert opinion: ATRA presents interesting properties to be used in anticancer therapy with a notorious differentiation and antimetastatic activity. Bioavailability and resistance limitations impair the use of ATRA in non-APL cancers. Nanotechnology can circumvent these issues and provide tools to enhance its anticancer activities, such as co-loading of multiple drug and active targeting to tumor site.

Therapeutic Use of Valproic Acid and All-Trans Retinoic Acid in Acute Myeloid Leukemia-Literature Review and Discussion of Possible Use in Relapse after Allogeneic Stem Cell Transplantation

Even though allogeneic stem cell transplantation is the most intensive treatment for acute myeloid leukemia (AML), chemo-resistant leukemia relapse is still one of the most common causes of death for these patients, as is transplant-related mortality, i.e., graft versus host disease, infections, and organ damage. These relapse patients are not always candidates for additional intensive therapy or re-transplantation, and many of them have decreased quality of life and shortened expected survival. The efficiency of azacitidine for treatment of posttransplant AML relapse has been documented in several clinical trials. Valproic acid is an antiepileptic fatty acid that exerts antileukemic activity through histone deacetylase inhibition. The combination of valproic acid and all-trans retinoic acid (ATRA) is well tolerated even by unfit or elderly AML patients, and low-toxicity chemotherapy (e.g., azacitidine) can be added to this combination. The triple combination of azacitidine, valproic acid, and ATRA may therefore represent a low-intensity and low-toxicity alternative for these patients. In the present review, we review and discuss the general experience with valproic acid/ATRA in AML therapy and we discuss its possible use in low-intensity/toxicity treatment of post-allotransplant AML relapse. Our discussion is further illustrated by four case reports where combined treatments with sequential azacitidine/hydroxyurea, valproic acid, and ATRA were used.

Antidepressants Promote and Prevent Cancers

The review states that antidepressants (ADs) increase brain-derived neurotrophic factor (BDNF) transmission concomitantly in the brain and the blood: ADs increasing BDNF synthesis in specific areas of the central nervous system (CNS) could presumably affect megakaryocyte's production of platelets. ADs increase BDNF levels in the CNS and improve mood. In the blood, ADs increase BDNF release from platelets. The hypothesis presented here is that the release of BDNF from platelets contributes to the ADs effects on neurogenesis and on tumor growth in the cancer disease. Oncological studies indicate that chemicals ADs exert an aggravating effect on the cancer disease, possibly by promoting proplatelets formation and enhancing BDNF release from platelets in the tumor.

Retinoic acid receptor γ activation promotes differentiation of human induced pluripotent stem cells into esophageal epithelium

BACKGROUND

The esophagus is known to be derived from the foregut. However, the mechanisms regulating this process remain unclear. In particular, the details of the human esophagus itself have been poorly researched. In this decade, studies using human induced pluripotent stem cells (hiPSCs) have proven powerful tools for clarifying the developmental biology of various human organs. Several studies using hiPSCs have demonstrated that retinoic acid (RA) signaling promotes the differentiation of foregut into tissues such as lung and pancreas. However, the effect of RA signaling on the differentiation of foregut into esophagus remains unclear.

METHODS

We established a novel stepwise protocol with transwell culture and an air-liquid interface system for esophageal epithelial cell (EEC) differentiation from hiPSCs. We then evaluated the effect of all-trans retinoic acid (ATRA), which is a retinoic acid receptor (RAR)α, RARβ and RARγ agonist, on the differentiation from the hiPSC-derived foregut. Finally, to identify which RAR subtype was involved in the differentiation, we used synthetic agonists and antagonists of RARα and RARγ, which are known to be expressed in esophagus.

RESULTS

We successfully generated stratified layers of cells expressing EEC marker genes that were positive for lugol staining. The enhancing effect of ATRA on EEC differentiation was clearly demonstrated with quantitative reverse transcription polymerase chain reaction, immunohistology, lugol-staining and RNA sequencing analyses. RARγ agonist and antagonist enhanced and suppressed EEC differentiation, respectively. RARα agonist had no effect on the differentiation.

CONCLUSION

We revealed that RARγ activation promotes the differentiation of hiPSCs-derived foregut into EECs.

All-Trans Retinoic Acid Inhibits Migration and Invasiveness of Rheumatoid Fibroblast-Like Synoviocytes

Fibroblast-like synoviocytes (FLSs) are pivotal in inflammation and joint damage of rheumatoid arthritis (RA). They acquire an active and aggressive phenotype, displaying increased migration and invasiveness and contributing to perpetuate synovial inflammation and destruction of cartilage and bone. The main current therapies of RA are focused against inflammatory factors and immune cells; however, a significant percentage of patients do not successfully respond. Combined treatments with drugs that control inflammation and that reverse the pathogenic phenotype of FLS could improve the prognosis of these patients. An unexplored area includes the retinoic acid, the main biologic retinoid, which is a candidate drug for many diseases but has reached clinical use only for a few. Here, we explored the effect of all-trans retinoic acid (ATRA) on the aggressive phenotype of FLS from patients with RA. RA FLSs were treated with ATRA, tumor necrosis factor (TNF), or TNF+ATRA, and cell migration and invasion were analyzed. In addition, a microarray analysis of expression, followed by gene-set analysis and quantitative polymerase chain reaction validation, was performed. We showed that ATRA induced a notable decrease in FLS migration and invasion that was accompanied by complex changes in gene expression. At supraphysiological doses, many of these effects were overridden or reverted by the concomitant presence of TNF. In conclusion, these results have demonstrated the therapeutic potential of retinoic acid on RA FLS provided TNF could be counterbalanced, either with high ATRA doses or with TNF inhibitors. SIGNIFICANCE STATEMENT: All-trans retinoic acid (ATRA) reduced the rheumatoid arthritis (RA) fibroblast-like synoviocyte migration and invasiveness and down-regulated gene expression of cell motility and migration genes. At supraphysiological doses, some of these effects were reverted by tumor necrosis factor. Therefore, ATRA could be an RA drug candidate that would require high doses or combined treatment with anti-inflammatory drugs.

All-trans retinoic acid induces anti-tumor effects via STAT3 signaling inhibition in oral squamous cell carcinoma and oral dysplasia

BACKGROUND

Oral squamous cell carcinoma (OSCC), which may arise from oral dysplasia, is one of the most prevalent cancers around the world. In recent years, all-trans retinoic acid (ATRA) has shown great potential in cancer treatment. However, the molecular mechanism for the anti-tumor effects of ATRA remains unclear.

MATERIALS AND METHODS

After treated with ATRA, inhibition of cell proliferation of OSCC and oral dysplasia cell lines, CAL27 and DOK, respectively, was analyzed by a Cell Counting Kit-8 (CCK8) assay. The cell cycle arrest, cell apoptosis induction, and PD-L1 expression level were measured by flow cytometry. A small molecular inhibitor was utilized to block STAT3 pathway, and the related proteins expression was measured by Western Blot.

RESULTS

The present study demonstrated that ATRA inhibited cell proliferation at 5-75 μmol/L, arrested cell cycle at S and G2-phase, induced apoptosis effect in OSCC, and oral dysplasia cell line, CAL27 and DOK, respectively. ATRA led to inhibition of p-STAT3, p-JAK2, increased the level of p-ERK, and significantly decreased the PD-L1 expression. Moreover, targeting STAT3 signaling increased (P < .001) the level of cleaved caspase-3 and effectively (P < .001) decreased the expression of cyclin A2 and PD-L1. The effect of ATRA on cell growth inhibition, apoptosis induction, and PD-L1 expression decrease was significantly (P < .05) enhanced after the STAT3 signaling blockade.

CONCLUSION

These findings suggested that ATRA-induced anti-tumor effects and downregulated PD-L1 expression via STAT3 signaling inhibition in both OSCC and oral dysplasia.

The potential of retinoids for combination therapy of lung cancer: Updates and future directions

Lung cancer is the most common cancer-related death worldwide. Natural compounds have shown high biological and pharmaceutical relevance as anticancer agents. Retinoids are natural derivatives of vitamin A having many regulatory functions in the human body, including vision, cellular proliferation and differentiation, and activation of tumour suppressor genes. Retinoic acid (RA) is a highly active retinoid isoform with promising anti-lung cancer activity. The abnormal expression of retinoid receptors is associated with loss of anticancer activities and acquired resistance to RA in lung cancer. The preclinical promise has not translated to the general clinical utility of retinoids for lung cancer patients, especially those with a history of smoking. Newer retinoid nano-formulations and the combinatorial use of retinoids has been associated with lower toxicity and more favorably efficacy in both the preclinical and clinical settings. Here, we highlight epidemiological and clinical therapeutic studies involving retinoids and lung cancer. We also discuss the biological actions of retinoids in lung cancer, which include effects on cancer stem cell differentiation, angiogenesis, metastasis, and proliferative. We suggest that the use of retinoids in combination with conventional and targeted anticancer agents will broaden the utility of these potent anticancer compounds in the lung cancer clinic.

Myeloid Derived Suppressor Cells Interactions With Natural Killer Cells and Pro-angiogenic Activities: Roles in Tumor Progression

Myeloid-derived suppressor cells (MDSCs) contribute to the induction of an immune suppressive/anergic, tumor permissive environment. MDSCs act as immunosuppression orchestrators also by interacting with several components of both innate and adaptive immunity. Natural killer (NK) cells are innate lymphoid cells functioning as primary effector of immunity, against tumors and virus-infected cells. Apart from the previously described anergy and hypo-functionality of NK cells in different tumors, NK cells in cancer patients show pro-angiogenic phenotype and functions, similar to decidual NK cells. We termed the pro-angiogenic NK cells in the tumor microenvironment "tumor infiltrating NK" (TINKs), and peripheral blood NK cells in cancer patients "tumor associated NK" (TANKs). The contribution of MDSCs in regulating NK cell functions in tumor-bearing host, still represent a poorly explored topic, and even less is known on NK cell regulation of MDSCs. Here, we review whether the crosstalk between MDSCs and NK cells can impact on tumor onset, angiogenesis and progression, focusing on key cellular and molecular interactions. We also propose that the similarity of the properties of tumor associated/tumor infiltrating NK and MDSC with those of decidual NK and decidual MDSCs during pregnancy could hint to a possible onco-fetal origin of these pro-angiogenic leukocytes.

Combined detection of IL-6 and IL-8 is beneficial to the diagnosis of early stage esophageal squamous cell cancer: a preliminary study based on the screening of serum markers using protein chips

Background

The diagnosis rate of early stage esophageal squamous cell carcinoma (ESCC) is low due to the lack of specific tumor markers. Seeking for these markers is beneficial to improve the early diagnosis rate and the prognosis of patients. This study profiles the differentially expressed proteins of early stage ESCC patients via the AAH-BLG-507 protein chip, which further consolidates the clinical evidence of ESCC diagnosis.

Materials and methods

In this study, 20 serum samples were collected from Taihe Hospital between August 2016 and June 2017. Ten of them carried ESCC, while the rest were healthy controls. To profile the proteins’ expression level, the AAH-BLG-507 protein chip was used, and both highly expressed and lowly expressed proteins were fished out. Meanwhile, their biological roles were examined by using Gene Ontology (GO) database and String database, and they were further verified by ELISA.

Results

Results showed that the expression levels of AXL, ARTN, Ang2, BDNF, BMP7, cripto-1, CCL28, E-selectin, IL-6, IL-8 and SHH in the serum of early ESCC were significantly upregulated (P<0.05), particularly IL-6 and IL-8. The expression levels of TSP1 and MMP-8 were markedly downregulated (P<0.05). Analysis showed that these proteins were mainly involved in angiogenesis, signal transduction, cell proliferation and migration, indicating the close relationship with the development of ESCC.

Conclusion

It suggested that IL-6 and IL-8 proteins could be considered as the markers for ESCC diagnosis.

[Effect of gap junction modulation on antitumor effects of adriamycin in estrogen receptor-positive breast cancer cells]

OBJECTIVE

To observe the effect of functional modulation of gap junctions (GJ) on the antitumor effect of adriamycin in breast cancer cells positive for estrogen receptor (ER).

METHODS

The inhibitory effect of 0 to 24.0 μmol/L adriamycin on the surviving fraction of ER-positive human breast cancer MCF-7 cells and ER-negative MDA-MB-231 cells was assessed with MTT assay; Western blotting and immunofluorescence assay were used to detect the expressions of Cx43 total protein and membrane protein in the cells. A parachute assay was used to evaluate the function of the GJ in MCF-7 cells. The cytotoxic effect of adriamycin was observed in the cells treated with retinoic acid (RA) for enhancing GJ function, in cells treated with oleamide and 18-α- glycyrrhizic acid (18-α-ga) for inhibiting GJ function, and also in cells transfected with Cx43siRNA for Cx43 knockdown.

RESULTS

ER-positive MCF-7 cells expressed a significantly higher level of Cx43 with stronger GJ function than ER-negative MDA- MB-231 cells. Adriamycin significantly inhibited the proliferation of MCF-7 cells (P < 0.01), and RA treatment further increased the cytotoxicity of adriamycin (P < 0.01) while oleamide and 18-α-GA obviously attenuated the cytotoxicity of adriamycin (P < 0.01). In the cells with Cx43 knockdown, the expressions of total Cx43 protein and Cx43 on the membrane were significantly reduced, the function of GJ was attenuated, and the cytotoxicity of adriamycin was significantly decreased (P < 0.01).

CONCLUSIONS

ER-positive breast cancer cells have stronger Cx43 expressions and GJ function than the ERnegative cells. The cytotoxicity of adriamycin against the breast cancer cells can be strengthened by enhancing GJ function and attenuated by inhibiting GJ function. Cx43 silencing inhibits the function of GJ to lower the cytotoxicity of adriamycin in human breast cancer MCF-7 cells.

Recent progress in natural dietary non-phenolic bioactives on cancers metastasis

From several decades ago to now, cancer continues to be the leading cause of death worldwide, and metastasis is the major cause of cancer-related deaths. For health benefits, there is a great desire to use non-chemical therapy such as nutraceutical supplementation to prevent pathology development. Over 10,000 different natural bioactives or phytochemicals have been known that possessing potential preventive or supplementary effects for various diseases including cancer. Previously, the in vitro and in vivo anti-invasive and anti-metastatic activities of phenolic acids, monophenol, polyphenol and their derivatives and flavonoids and their derivatives have been reviewed. However, a vast number of natural dietary compounds other than phenolics have been demonstrated to potentially possess the ability to inhibit the invasion and metastasis of various cancers. In this review, we summarize the studies in recent decade on in vitro and in vivo effects and molecular mechanisms of natural bioactives, excluding the phenolics in food, in cancer invasion and metastasis. By combining this review of non-phenolics with the previous phenolics reviews, the puzzle for the contribution of natural dietary bioactives on cancer invasive or/and metastatic progress will be almost complete and more clear.

Involvement of MAFB and MAFF in Retinoid-Mediated Suppression of Hepatocellular Carcinoma Invasion

Retinoids exert antitumor effects through the retinoic acid receptor α (RARα). In the present study, we sought to identify the factors involved in the RARα-mediated transcriptional regulation of the tumor suppressor gene and the tissue factor pathway inhibitor 2 (TFPI2) in hepatocellular carcinoma (HCC). All-trans-retinoic acid (ATRA) was used in the in vitro experiments. Cell invasiveness was measured using trans-well invasion assay. ATRA significantly increased TFPI2 expression through RARα in a human HCC cell line known as HuH7. TFPI2 was vital in the ATRA-mediated suppression of HuH7 cell invasion. The musculo-aponeurotic fibrosarcoma oncogene homolog B (MAFB) significantly enhanced the activation of the TFPI2 promoter via RARα while MAFF inhibited it. The knockdown of RARα or MAFB counteracted the ATRA-mediated suppression of HuH7 cell invasion while the knockdown of MAFF inhibited the invasion. TFPI2 expression in HCC tissues was significantly downregulated possibly due to the decreased expression of RARβ and MAFB. Patients with HCC expressing low MAFB and high MAFF levels showed the shortest disease-free survival time. These results suggest that MAFB and MAFF play critical roles in the antitumor effects of retinoids by regulating the expression of retinoid target genes such as TFPI2 and can be promising for developing therapies to combat HCC invasion.

β-Cryptoxanthin Inhibits Angiogenesis in Human Umbilical Vein Endothelial Cells Through Retinoic Acid Receptor

SCOPE

β-Cryptoxanthin is an abundant carotenoid in fruits and vegetables that can be quantified in human blood serum. Yet, contrary to other carotenoids, its effects on endothelial cells and angiogenesis remain unknown.

METHODS AND RESULTS

Human umbilical vein endothelial cells (HUVEC) are treated with 0.01, 0.1, or 1 μm of β-cryptoxanthin. Antioxidant activity is determined by its free radical scavenging and oxygen-radical absorbance capacity. The effect on migration and formation of tubular structures is studied. Additionally, effect on angiogenesis is also analyzed using an in vivo model. β-Cryptoxanthin exhibits scavenging ability, having an antioxidant effect on HUVEC. Interestingly, β-cryptoxanthin reduces their migration and angiogenesis, even in the presence of vascular endothelial growth factor (VEGF). Additionally, such carotenoid inhibits in vivo angiogenesis induced by VEGF. In addition, treatment of HUVEC with LE540 (retinoic acid receptor [RAR] panantagonist) inhibits β-cryptoxanthin antiangiogenic effect on HUVEC.

CONCLUSION

β-Cryptoxanthin inhibits angiogenesis through RAR. Thus, this carotenoid and food containing it may be useful for the prevention and treatment of angiogenic pathologies. That includes tumoral growth and wet macular degeneration associated with aging. To the best of our knowledge, this is the first report of the antioxidant effect and antiangiogenic activity of this carotenoid on HUVEC, both in vitro and in vivo.

Retinoic acid regulates endometriotic stromal cell growth through upregulation of Beclin1

PURPOSE

To elucidate the role of retinoic acid (RA) in autophagy-mediated endometriosis.

METHODS

The mRNA and protein expressions of autophagy markers were examined in Ishikawa cells and endometriotic stromal cells (ESCs) after RA treatment. Beclin1 expression was specifically analyzed in clinical samples of endometriosis. The effect of Beclin1 knockdown on ESC growth was assessed, and the effect of autophagy inhibition on the sensitivity of endometriotic cells to RA was analyzed.

RESULTS

RA treatment enhanced the autophagy in ESCs, and Beclin1 expression showed a negative correlation with the clinical stage of endometriosis. Beclin1 knockdown enhanced ESC growth, whereas RA treatment reversed this effect. Furthermore, inhibition of autophagy by chloroquine (CQ) and Beclin1 knockdown did not show any positive effect on the sensitivity of endometriotic cells to RA.

CONCLUSIONS

RA treatment induces autophagy and Beclin1 may play an important role in endometriosis progression.