Expression profiles of Id1 and p16 proteins in all-trans-retinoic acid-induced apoptosis and cell cycle re-distribution in melanoma

Retinoic Acid Inhibits Tumor-Associated Mesenchymal Stromal Cell Transformation in Melanoma

Bone marrow mesenchymal stem/stromal cells (BMSCs) can be transformed into tumor-associated MSCs (TA-MSCs) within the tumor microenvironment to facilitate tumor progression. However, the underline mechanism and potential therapeutic strategy remain unclear. Here, we explored that interleukin 17 (IL-17) cooperating with IFNγ transforms BMSCs into TA-MSCs, which promotes tumor progression by recruiting macrophages/monocytes and myeloid-derived suppressor cells (MDSCs) in murine melanoma. IL-17 and IFNγ transformed TA-MSCs have high expression levels of myelocyte-recruiting chemokines (CCL2, CCL5, CCL7, and CCL20) mediated by activated NF-κB signaling pathway. Furthermore, retinoic acid inhibits NF-κB signaling, decreases chemokine expression, and suppresses the tumor-promoting function of transformed TA-MSCs by prohibiting the recruitment of macrophages/monocytes and MDSCs in the tumor microenvironment. Overall, our findings demonstrate that IL-17 collaborating with IFNγ to induce TA-MSC transformation, which can be targeted by RA for melanoma treatment.

Perfluorooctanoic acid induces gene promoter hypermethylation of glutathione-S-transferase Pi in human liver L02 cells

Perfluorooctanoic acid (PFOA) is one of the most commonly used perfluorinated compounds. Being a persistent environmental pollutant, it can accumulate in human tissues via various exposure routes. PFOA may interfere in a toxic fashion on the immune system, liver, development, and endocrine systems. In utero human exposure had been associated with cord serum global DNA hypomethylation. In light of this, we investigated possible PFOA-induced DNA methylation alterations in L02 cells in order to shed light into its epigenetic-mediated mechanisms of toxicity in human liver. L02 cells were exposed to 5, 10, 25, 50 or 100 mg/L PFOA for 72h. Global DNA methylation levels were determined by LC/ESI-MS, glutathione-S-transferase Pi (GSTP) gene promoter DNA methylation was investigated by methylation-specific polymerase chain reaction (PCR) with bisulfite sequencing, and consequent mRNA expression levels were measured with quantitative real-time reverse transcriptase PCR. A dose-related increase of GSTP promoter methylation at the transcription factor specificity protein 1 (SP1) binding site was observed. However, PFOA did not significantly influence global DNA methylation; nor did it markedly alter the promoter gene methylation of p16 (cyclin-dependent kinase inhibitor 2A), ERα (estrogen receptor α) or PRB (progesterone receptor B). In addition, PFOA significantly elevated mRNA transcript levels of DNMT3A (which mediates de novo DNA methylation), Acox (lipid metabolism) and p16 (cell apoptosis). Considering the role of GSTP in detoxification, aberrant methylation may be pivotal in PFOA-mediated toxicity response via the inhibition of SP1 binding to GSTP promoter.

Retinoids, retinoic acid receptors, and cancer

Retinoids (i.e., vitamin A, all-trans retinoic acid, and related signaling molecules) induce the differentiation of various types of stem cells. Nuclear retinoic acid receptors mediate most but not all of the effects of retinoids. Retinoid signaling is often compromised early in carcinogenesis, which suggests that a reduction in retinoid signaling may be required for tumor development. Retinoids interact with other signaling pathways, including estrogen signaling in breast cancer. Retinoids are used to treat cancer, in part because of their ability to induce differentiation and arrest proliferation. Delivery of retinoids to patients is challenging because of the rapid metabolism of some retinoids and because epigenetic changes can render cells retinoid resistant. Successful cancer therapy with retinoids is likely to require combination therapy with drugs that regulate the epigenome, such as DNA methyltransferase and histone deacetylase inhibitors, as well as classical chemotherapeutic agents. Thus, retinoid research benefits both cancer prevention and cancer treatment.

Randomized Phase II Trial of All-Trans-Retinoic Acid With Chemotherapy Based on Paclitaxel and Cisplatin As First-Line Treatment in Patients With Advanced Non–Small-Cell Lung Cancer

Purpose

This randomized phase II trial evaluated whether the combination of cisplatin and paclitaxel (PC) plus all-trans retinoic acid (ATRA) increases response rate (RR) and progression-free survival (PFS) in patients with advanced non–small-cell lung cancer (NSCLC) with an acceptable toxicity profile and its association with the expression of retinoic acid receptor beta 2 (RAR-β2) as a response biomarker.

Patients and Methods

Patients with stages IIIB with pleural effusion and IV NSCLC were included to receive PC, and randomly assigned to receive ATRA 20 mg/m2/d (RA/PC) or placebo (P/PC) 1 week before treatment until two cycles were completed. RAR-β2 expression was analyzed in tumor and adjacent lung tissue.

Results

One hundred seven patients were included, 55 in the P/PC group and 52 in the RA/PC group. RR for RA/PC was 55.8% (95% CI, 46.6% to 64.9%) and for P/PC, 25.4% (95% CI, 21.3 to 29.5%; P = .001). The RA/PC group had a longer median PFS (8.9 v 6.0 months; P = .008). Multivariate analysis of PFS showed significant differences for the RA/PC group (hazard ratio, 0.62; 95% CI, 0.4 to 0.95). No significant differences in toxicity grade 3/4 were found between groups, except for hypertriglyceridemia (10% v 0%) in RA/PC (P = .05). Immunohistochemistry and reverse-transcriptase polymerase chain reaction assays showed expression of RAR-β2 in normal tissues of all tumor samples, but only 10% of samples in the tumor tissue.

Conclusion

Adding ATRA to chemotherapy could increase RR and PFS in patients with advanced NSCLC with an acceptable toxicity profile. A phase III clinical trial is warranted to confirm these findings.

Evidence of a novel antiapoptotic factor: role of inhibitor of differentiation or DNA binding (Id-1) in anticancer drug-induced apoptosis

Id-1 (inhibitor of differentiation or DNA binding), a member of the basic helix-loop-helix transcription factor family, is up-regulated in many types of human cancer and its expression levels are correlated with poor treatment outcome and shorter survival. In this study, we provided evidence to suggest that Id-1 is a universal survival factor that plays a key role in protection against anticancer drug-induced apoptosis. Using nine anticancer drugs and five cancer cell lines derived from nasopharyngeal carcinoma (CNE1), cervical carcinoma (HeLa), breast cancer (MCF7), hepatocarcinoma (Huh7) and prostate cancer (PC3), we found that down-regulation of Id-1 expression at both transcriptional and protein levels was associated with increased apoptosis rates and increased cleaved PARP after exposure to all anticancer agents. Treatment with a caspase 9 inhibitor, Z-LEHD-FMK, protected cancer cells from drug-induced PARP cleavage. However, overexpression of Id-1 in a p53 mutated cell line, CNE1, was able to suppress PARP cleavage in response to all anticancer drugs examined. In contrast, down-regulation of Id-1 through small RNA technology in CNE1 cells led to increased sensitivity to all six types of chemotherapeutic drugs. Our results demonstrate that Id-1 may be a general negative regulator of anticancer drug-induced apoptosis and suggest a novel therapeutic target in inducing chemosensitization in cancer cells. Our evidence also provides a possible underlying mechanism responsible for the positive role of Id-1 in the progression of human cancer.

Melanoma chemoprevention

BACKGROUND

Despite efforts to promote sun protection behaviors, melanoma incidence continues to increase. The prognosis of advanced melanoma remains extremely poor in spite of treatment advances, emphasizing the importance of exploring additional preventive measures.

OBJECTIVE

We sought to summarize the results of published research on candidate chemoprevention agents for melanoma.

METHODS

We conducted a narrative review of the literature.

RESULTS

Investigation into a possible role in melanoma chemoprevention continues for multiple agents, including sunscreen, lipid-lowering medications, nonsteroidal anti-inflammatory drugs, dietary nutrients, immunomodulators, and other drugs, including retinoids, difluoromethylornithine, and T4 endonuclease V.

LIMITATIONS

Systematic review of the literature was not performed.

CONCLUSION

Because no agent yet emerges as a clear choice for effective melanoma chemoprevention, sun avoidance and sun protection remain the mainstay of melanoma prevention for persons at high risk.

Expression of the helix–loop–helix protein inhibitor of DNA binding-1 (ID-1) is activated by all-trans retinoic acid in normal human keratinocytes

The ID (inhibitor of differentiation or DNA binding) helix-loop-helix proteins are important mediators of cellular differentiation and proliferation in a variety of cell types through regulation of gene expression. Overexpression of the ID proteins in normal human keratinocytes results in extension of culture lifespan, indicating that these proteins are important for epidermal differentiation. Our hypothesis is that the ID proteins are targets of the retinoic acid signaling pathway in keratinocytes. Retinoids, vitamin A analogues, are powerful regulators of cell growth and differentiation and are widely used in the prevention and treatment of a variety of cancers in humans. Furthermore, retinoic acid is necessary for the maintenance of epithelial differentiation and demonstrates an inhibitory action on skin carcinogenesis. We examined the effect of all-trans retinoic acid on expression of ID-1, -2, -3, and -4 in normal human keratinocytes and found that exposure of these cells to all-trans retinoic acid causes an increase in both ID-1 and ID-3 gene expression. Furthermore, our data show that this increase is mediated by increased transcription involving several cis-acting elements in the distal portion of the promoter, including a CREB-binding site, an Egr1 element, and an YY1 site. These data demonstrate that the ID proteins are direct targets of the retinoic acid signaling pathway. Given the importance of the ID proteins to epidermal differentiation, these results suggest that IDs may be mediating some of the effects of all-trans retinoic acid in normal human keratinocytes.

Disruption of the lecithin:retinol acyltransferase gene makes mice more susceptible to vitamin A deficiency

Lecithin:retinol acyltransferase (LRAT) catalyzes the esterification of retinol (vitamin A) in the liver and in some extrahepatic tissues, including the lung. We produced an LRAT gene knock-out mouse strain and assessed whether LRAT-/- mice were more susceptible to vitamin A deficiency than wild type (WT) mice. After maintenance on a vitamin A-deficient diet for 6 weeks, the serum retinol level was 1.34 +/- 0.32 microM in WT mice versus 0.13 +/- 0.06 microM in LRAT-/- mice (p < 0.05). In liver, lung, eye, kidney, brain, tongue, adipose tissue, skeletal muscle, and pancreas, the retinol levels ranged from 0.05 pmol/mg (muscle and tongue) to 17.35 +/- 2.66 pmol/mg (liver) in WT mice. In contrast, retinol was not detectable (<0.007 pmol/mg) in most tissues from LRAT-/- mice after maintenance on a vitamin A-deficient diet for 6 weeks. Cyp26A1 mRNA was not detected in hepatic tissue samples from LRAT-/- mice but was detected in WT mice fed the vitamin A-deficient diet. These data indicate that LRAT-/- mice are much more susceptible to vitamin A deficiency and should be an excellent animal model of vitamin A deficiency. In addition, the retinol levels in serum rapidly increased in the LRAT-/- mice upon re-addition of vitamin A to the diet, indicating that serum retinol levels in LRAT-/- mice can be conveniently modulated by the quantitative manipulation of dietary retinol.