Identification and effective regulation of scarb1 gene involved in pigmentation change in autotetraploid Carassius auratus

The autotetraploid Carassius auratus (4nRR, 4 n=200, RRRR) is derived from whole-genome duplication of Carassius auratus red var. (RCC, 2 n=100, RR). In the current study, we demonstrated that chromatophores and pigment changes directly caused the coloration and variation of 4nRR skin (red in RCC, brownish-yellow in 4nRR). To further explore the molecular mechanisms underlying coloration formation and variation in 4nRR, we performed transcriptome profiling and molecular functional verification in RCC and 4nRR. Results revealed that scarb1, associated with carotenoid metabolism, underwent significant down-regulation in 4nRR. Efficient editing of this candidate pigment gene provided clear evidence of its significant role in RCC coloration. Subsequently, we identified four divergent scarb1 homeologs in 4nRR: two original scarb1 homeologs from RCC and two duplicated ones. Notably, three of these homeologs possessed two highly conserved alleles, exhibiting biased and allele-specific expression in the skin. Remarkably, after precise editing of both the original and duplicated scarb1 homeologs and/or alleles, 4nRR individuals, whether singly or multiply mutated, displayed a transition from brownish-yellow skin to a cyan-gray phenotype. Concurrently, the proportional areas of the cyan-gray regions displayed a gene-dose correlation. These findings illustrate the subfunctionalization of duplicated scarb1, with all scarb1 genes synergistically and equally contributing to the pigmentation of 4nRR. This is the first report concerning the functional differentiation of duplicated homeologs in an autopolyploid fish, substantially enriching our understanding of coloration formation and change within this group of organisms.

Integrated Whole-Exome and Transcriptome Sequencing Indicated Dysregulation of Cholesterol Metabolism in Eyelid Sebaceous Gland Carcinoma

Purpose

To identify the molecular background of eyelid sebaceous gland carcinomas (SCs), we conducted the integrated whole-exome sequencing and transcriptome sequencing for eyelid SCs in this study.

Methods

The genetic alterations were studied by whole-exome sequencing, and the messenger RNA expression was studied using Oxford Nanopore Technologies (ONT) in five paired fresh eyelid SC tissues and adjacent normal tissues. Integrated analysis of exome and transcriptomic information was conducted for filtering candidate driver genes. Protein-protein interaction (PPI) network of filtered candidate genes was analyzed by STRING. The protein expression was verified by immunohistochemistry in 29 eyelid SCs and 17 compared normal sebaceous gland tissues.

Results

The average numbers of pathogenic somatic single-nucleotide variants (SNVs) and indels in eyelid SCs were 75 and 28, respectively. Tumor protein p53 (TP53), zinc finger protein 750 (ZNF750), filaggrin 2 (FLG2), valosin-containing protein (VCP), and zinc finger protein 717 (ZNF717) were recurrent mutated genes. A mean of 844 differentially expressed genes (DEGs) were upregulated, and 1401 DEGs were downregulated in SC samples. The intersection of DEG-based pathways and mutation-based pathways was mainly involved in microbial infection and inflammation, immunodeficiency, cancer, lipid metabolism, and the other pathways. The intersection of DEGs and mutated genes consisted of 55 genes, of which 15 genes formed a PPI network with 4 clusters. The PPI cluster composed of scavenger receptor class B member 1 (SCARB1), peroxisome proliferator-activated receptor γ (PPARG), peroxisome proliferator-activated receptor γ coactivator 1α (PPARGC1A) was involved in cholesterol metabolism. The expression of SCARB1 protein was found to be increased, whereas that of PPARG protein was decreased in eyelid SCs compared to that in the normal sebaceous glands.

Conclusions

Increased SCARB1 and decreased PPARG indicated that dysregulation of cholesterol metabolism might be involved in carcinogenesis of eyelid SCs.

Translational Relevance

The malfunction in cholesterol metabolism might advance our knowledge of the carcinogenesis of eyelid SCs.

Cholesterol Auxotrophy as a Targetable Vulnerability in Clear Cell Renal Cell Carcinoma

Clear cell renal cell carcinoma (ccRCC) is characterized by large intracellular lipid droplets containing free and esterified cholesterol; however, the functional significance of cholesterol accumulation in ccRCC cells is unknown. We demonstrate that, surprisingly, genes encoding cholesterol biosynthetic enzymes are repressed in ccRCC, suggesting a dependency on exogenous cholesterol. Mendelian randomization analyses based on 31,000 individuals indicate a causal link between elevated circulating high-density lipoprotein (HDL) cholesterol and ccRCC risk. Depriving ccRCC cells of either cholesterol or HDL compromises proliferation and survival in vitro and tumor growth in vivo; in contrast, elevated dietary cholesterol promotes tumor growth. Scavenger Receptor B1 (SCARB1) is uniquely required for cholesterol import, and inhibiting SCARB1 is sufficient to cause ccRCC cell-cycle arrest, apoptosis, elevated intracellular reactive oxygen species levels, and decreased PI3K/AKT signaling. Collectively, we reveal a cholesterol dependency in ccRCC and implicate SCARB1 as a novel therapeutic target for treating kidney cancer.

SIGNIFICANCE

We demonstrate that ccRCC cells are auxotrophic for exogenous cholesterol to maintain PI3K/AKT signaling pathway and ROS homeostasis. Blocking cholesterol import through the HDL transporter SCARB1 compromises ccRCC cell survival and tumor growth, suggesting a novel pharmacologic target for this disease. This article is highlighted in the In This Issue feature, p. 2945.

Corticosteroid Therapy Benefits Septic Mice With Adrenal Insufficiency But Harms Septic Mice Without Adrenal Insufficiency

OBJECTIVES

Corticosteroid therapy is frequently used in septic patients given the rationale that there is an increased demand for corticosteroid in sepsis, and up to 60% of severe septic patients experience adrenal insufficiency. However, the efficacy of corticosteroid therapy and whether the therapy should be based on the results of adrenal function testing are highly controversial. The lack of an adrenal insufficiency animal model and our poor understanding of the pathogenesis caused by adrenal insufficiency present significant barriers to address this long-standing clinical issue.

DESIGN

Prospective experimental study.

SETTING

University laboratory.

SUBJECTS

Scavenger receptor BI null and adrenal-specific scavenger receptor BI null mice.

INTERVENTIONS

Sepsis was induced by cecal ligation and puncture.

MEASUREMENTS AND MAIN RESULTS

Using scavenger receptor BI mice as the first relative adrenal insufficiency animal model, we found that corticosteroid therapy significantly improved the survival in cecal ligation and puncture-treated scavenger receptor BI mice but causes more septic death in wild-type mice. We identified a corticosteroid cocktail that provides effective protection 18 hours post cecal ligation and puncture; using adrenal-specific scavenger receptor BI mice as an inducible corticosteroid-deficient animal model, we found that inducible corticosteroid specifically suppresses interleukin-6 production without affecting tumor necrosis factor-α, nitric oxide, and interleukin-10 production. We further found that inducible corticosteroid does not induce peripheral lymphocyte apoptosis but promotes phagocytic activity of macrophages and neutrophils.

CONCLUSIONS

This study demonstrates that corticosteroid treatment benefits mice with adrenal insufficiency but harms mice without adrenal insufficiency. This study also reveals that inducible corticosteroid has both immunosuppressive and immunopermissive properties, suppressing interleukin-6 production, promoting phagocytosis of immune effector cells, but not inducing peripheral lymphocyte apoptosis. These findings support our hypothesis that corticosteroid is an effective therapy for a subgroup of septic patients with adrenal insufficiency but harms septic patients without adrenal insufficiency and encourage further efforts to test this hypothesis in clinic.

The HDL receptor SR-BI is associated with human prostate cancer progression and plays a possible role in establishing androgen independence

BACKGROUND

Human prostate cancer represents one of the most frequently diagnosed cancers in men worldwide. Currently, diagnostic methods are insufficient to identify patients at risk for aggressive prostate cancer, which is essential for early treatment. Recent data indicate that elevated cholesterol levels in the plasma are a prerequisite for the progression of prostate cancer. Here, we analyzed clinical prostate cancer samples for the expression of receptors involved in cellular cholesterol uptake.

METHODS

We screened mRNA microarray files of prostate cancer samples for alterations in the expression levels of cholesterol transporters. Furthermore, we performed immunohistochemistry analysis on human primary prostate cancer tissue sections derived from patients to investigate the correlation of SR-BI with clinicopathological parameters and the mTOR target pS6.

RESULTS

In contrast to LDLR, we identified SR-BI mRNA and protein expression to be induced in high Gleason grade primary prostate cancers. Histologic analysis of prostate biopsies revealed that 53.6 % of all cancer samples and none of the non-cancer samples showed high SR-BI staining intensity. The disease-free survival time was reduced (P = 0.02) in patients expressing high intra-tumor levels of SR-BI. SR-BI mRNA correlated with HSD17B1 and HSD3B1 and SR-BI protein staining showed correlation with active ribosomal protein S6 (RS = 0.828, P < 0.00001).

CONCLUSIONS

We identified SR-BI to indicate human prostate cancer formation, suggesting that increased levels of SR-BI may be involved in the generation of a castration-resistant phenotype.