Association of germline rare pathogenic mutations in guideline-recommended genes with prostate cancer progression: A meta-analysis.

BACKGROUND: Germline mutations in several genes, mainly DNA repair genes, have been associated with prostate cancer (PCa) progression. However, primarily due to the rarity of mutations, statistical evidence for these associations is not consistently established. The objective of this study is to synthesize evidence from multiple studies using a meta-analysis. METHODS: Genes analyzed were chosen based on National Comprehensive Cancer Network guidelines recommendations (10 genes) and a commonly reported gene (NBN). PCa progression in this analysis was defined as either having metastases or PCa-specific mortality. We searched PubMed for papers published before April 26, 2021, using selected keywords. Pooled odds ratio (OR) was estimated in all races and Caucasians-only using both fixed- and random-effect models. RESULTS: The search identified 1028 papers and an additional five from a manual review of references. After a manual process that excluded noneligible studies, 11 papers remained, including a total of 3944 progressors and 20,054 nonprogressors. Combining results from these eligible studies, mutation carrier rates were significantly higher in progressors than nonprogressors for NBN, BRCA2, ATM (under both fixed- and random-effect models), for CHEK2 (under fixed-effect model only), and for PALB2 (under random-effect model only), p < 0.05. Pooled OR (95% confidence interval) was 6.38 (2.25-18.05), 3.41 (2.31; 5.03), 1.93 (1.17-3.20), and 1.53 (1.00-2.33) for NBN, BRCA2, ATM, and CHEK2, respectively, under fixed-effect model and 2.63 (1.12-6.13) for PALB2 under random-effect model. No significant association was found for the six remaining genes. Certainty of evidence was low for many genes due primarily to the limited number of eligible studies and mutation carriers. CONCLUSIONS: Statistical evidence for five genes was obtained in this first meta-analysis of germline mutations and PCa progression. While these results may help urologists and genetic counselors interpret germline testing results for PCa progression, more original studies are needed.

Observed evidence for guideline-recommended genes in predicting prostate cancer risk from a large population-based cohort.

BACKGROUND: Germline testing for prostate cancer (PCa) is now recommended by the National Comprehensive Cancer Network. While multi-gene testing has been proposed, evidence for their association with PCa risk is not well established. METHODS: We tested associations of pathogenic/likely pathogenic mutations in 10 guideline-recommended genes (ATM, BRCA1, BRCA2, CHEK2, PALB2, MLH1, MSH2, MSH6, PMS2, and HOXB13) with PCa risk in the UK Biobank, a population-based cohort. Mutations were annotated based on prostate-specific transcripts using the American College of Medical Genetics and Genomics standards. Associations were tested in 4399 PCa cases and 85,403 unaffected male controls using logistic regression adjusting for age and genetic background. p < .005 was considered significant based on Bonferroni correction. RESULTS: Among the 10 tested genes, significantly higher mutation carrier rates in PCa cases versus controls were found for four genes at p < .005; HOXB13, BRCA2, ATM, and CHEK2, with odds ratios (95% confidence interval) estimated at 4.96 (3.62-6.69), 3.23 (2.23-4.56), 2.95 (2.01-4.22), 1.94 (1.43-2.58), respectively. No significant association was found between mutation carrier status and age at PCa diagnosis or family history of PCa. Despite the large sample size of this study, statistical power remains limited, especially for genes where pathogenic mutation carrier rates are extremely rare (<0.03%). CONCLUSION: Observed evidence for PCa risk was found for four of the 10 guideline-recommended genes in this large population-based study. Mutations in these four genes can be interpreted with confidence in genetic counseling for PCa risk assessment. Evidence for the remaining six genes needs to be further evaluated in larger studies.

New structural insights into the recognition of undamaged splayed-arm DNA with a single pair of non-complementary nucleotides by human nucleotide excision repair protein XPA.

XPA (Xeroderma pigmentosum complementation group A) is a core scaffold protein that plays significant roles in DNA damage verification and recruiting downstream endonucleases in the nucleotide excision repair (NER) pathway. Here, we present the 2.81 Å resolution crystal structure of the DNA-binding domain (DBD) of human XPA in complex with an undamaged splayed-arm DNA substrate with a single pair of non-complementary nucleotides. The structure reveals that two XPA molecules bind to one splayed-arm DNA with a 10-bp duplex recognition motif in a non-sequence-specific manner. XPA molecules bind to both ends of the DNA duplex region with a characteristic ß-hairpin. A conserved tryptophan residue Trp175 packs against the last base pair of DNA duplex and stabilizes the conformation of the characteristic ß-hairpin. Upon DNA binding, the C-terminal last helix of XPA would shift towards the minor groove of the DNA substrate for better interaction. Notably, human XPA is able to bind to the undamaged DNA duplex without any kinks, and XPA-DNA binding does not bend the DNA substrate obviously. This study provides structural basis for the binding mechanism of XPA to the undamaged splayed-arm DNA with a single pair of non-complementary nucleotides.

Mulberry fruit prevents LPS-induced NF-κB/pERK/MAPK signals in macrophages and suppresses acute colitis and colorectal tumorigenesis in mice.

Here, we investigated the impact of mulberry fruit (MBF) extracts on lipopolysaccharide (LPS)-induced inflammatory responses in RAW 264.7 macrophages, and the therapeutic efficacy of MBF diet in mice with dextran sulfate sodium (DSS)-induced acute colitis and MUC2(-/-) mice with colorectal cancer. In vitro, LPS-induced nitric oxide (NO) production was significantly inhibited by MBF extracts via suppressing the expression of proinflammatory molecules, including inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin-1 beta (IL-ß) and IL-6. Particularly, a dose-dependent inhibition on LPS-induced inflammatory responses was observed following treatment with MBF dichloromethane extract (MBF-DE), in which linoleic acid and ethyl linolenate were identified as two active compounds. Moreover, we elucidated that MBF-DE attenuated LPS-induced inflammatory responses by blocking activation of both NF-κB/p65 and pERK/MAPK pathways. In vivo, DSS-induced acute colitis was significantly ameliorated in MBF-fed mice as gauged by weight loss, colon morphology and histological damage. In addition, MBF-fed MUC2(-/-) mice displayed significant decrease in intestinal tumor and inflammation incidence compared to control diet-fed group. Overall, our results demonstrated that MBF suppressed the development of intestinal inflammation and tumorgenesis both in vitro and in vivo, and supports the potential of MBF as a therapeutic functional food for testing in human clinical trials.

A Critical Role for Cysteine 57 in the Biological Functions of Selenium Binding Protein-1.

The concentration of selenium-binding protein1 (SBP1) is often lower in tumors than in the corresponding tissue and lower levels have been associated with poor clinical outcomes. SBP1 binds tightly selenium although what role selenium plays in its biological functions remains unknown. Previous studies indicated that cysteine 57 is the most likely candidate amino acid for selenium binding. In order to investigate the role of cysteine 57 in SBP1, this amino acid was altered to a glycine and the mutated protein was expressed in human cancer cells. The SBP1 half-life, as well as the cellular response to selenite cytotoxicity, was altered by this change. The ectopic expression of SBP1(GLY) also caused mitochondrial damage in HCT116 cells. Taken together, these results indicated that cysteine 57 is a critical determinant of SBP1 function and may play a significant role in mitochondrial function.

Molecular cross-talk between members of distinct families of selenium containing proteins.

Dietary intake of selenium has been associated with reduced risk of several cancer types, and this is likely due to its role as a specific constituent of selenium containing proteins. One of these, selenium-binding protein 1 (SBP1), is a protein of unknown function that has been shown to be reduced in tumors of diverse tissue types as compared to the corresponding normal tissue. More importantly, SBP1 has also been reported to be a predictor of clinical outcome. Levels of SBP1 are inversely associated with the levels of another protein representative of a different class of selenoproteins, glutathione peroxidase1 (GPx-1). GPx-1 is an anti-oxidant, selenocysteine containing enzyme implicated in several diseases, including cancer, due to the association of specific alleles with disease risk. The relationship between SBP1 and GPx-1 represents a unique example of a molecular interaction between selenium containing proteins with a likely significant impact on human health and disease.

Selenium and sulindac are synergistic to inhibit intestinal tumorigenesis in Apc/p21 mice.

BACKGROUND: Both selenium and non-steroidal anti-inflammatory drug (NSAID) sulindac are effective in cancer prevention, but their effects are affected by several factors including epigenetic alterations and gene expression. The current study was designed to determine the effects of the combination of selenium and sulindac on tumor inhibition and the underlying mechanisms. RESULTS: We fed the intestinal tumor model Apc/p21 mice with selenium- and sulindac-supplemented diet for 24 weeks, and found that the combination of selenium and sulindac significantly inhibited intestinal tumorigenesis, in terms of reducing tumor incidence by 52% and tumor multiplicities by 80% (p<0.01). Mechanistic studies revealed that the combination of selenium and sulindac led to the significant induction of the expression of p27 and p53 and JNK1 phosphorylation, and led to the suppression of ß-catenin and its downstream targets. Impressively, the data also showed that demythelation on p21 promoter was associated with tumor inhibition by the combination of selenium and sulindac. CONCLUSIONS: The selenium is synergistic with sulindac to exert maximal effects on tumor inhibition. This finding provides an important chemopreventive strategy using combination of anti-cancer agents, which has a great impact on cancer prevention and has a promising translational potential.

Functional and physical interaction between the selenium-binding protein 1 (SBP1) and the glutathione peroxidase 1 selenoprotein.

Selenium-binding protein (SBP) 1 is present in reduced levels in several cancer types as compared with normal tissues, and lower levels are associated with poor clinical prognosis. Another selenium-containing protein, glutathione peroxidase 1 (GPX1), has been associated with cancer risk and development. The interaction between these representatives of different classes of selenoproteins was investigated. Increasing SBP1 levels in either human colorectal or breast cancer cells by transfection of an expression construct resulted in the reduction of GPX1 enzyme activity. Increased expression of GPX1 in the same cell types resulted in the transcriptional and translational repression of SBP1, as evidenced by the reduction of SBP1 messenger RNA and protein and the inhibition of transcription measured using an SBP1 reporter construct. The opposing effects of SBP1 and GPX1 on each other were also observed when GPX1 was increased by supplementing the media of these tissue culture cells with selenium, and the effect of selenium on SBP1 was shown to be GPX1 dependent. Decreasing or increasing GPX1 levels in colonic epithelial cells of mice fed a selenium-deficient, -adequate or -supplemented diet resulted in the opposing effect on SBP1 levels. These data are explained in part by the demonstration that SBP1 and GPX1 form a physical association, as determined by coimmunoprecipitation and fluorescence resonance energy transfer assay. The results presented establish an interaction between two distinct selenium-containing proteins that may enhance the understanding of the mechanisms by which selenium and selenoproteins affect carcinogenesis in humans.

Anticancer activity of Panax notoginseng extract 20(S)-25-OCH3-PPD: Targetting beta-catenin signalling.

1. The Wnt/beta-catenin pathway plays a critical role in carcinogenesis and so agents that target Wnt/beta-catenin may have potential in cancer prevention and therapy. The aim of the present study was to evaluate the anticancer activity of the novel natural product dammarane-type triterpene sapogenin (20(S)-25-OCH3-PPD; PPD25) isolated from the leaves of Panax notoginseng. 2. The anticancer activity of PPD25 was evaluated in three colon cancer cell lines and in one lung cancer cell line. The effects of PPD25 to inhibit proliferation and to induce apoptosis were evaluated. In addition, the potential mechanisms underlying the effects of PPD25 were investigated. 3. It was found that the addition of 5 or 25 micromol/L PPD25 to the culture medium significantly inhibited cell proliferation and induced apoptosis in all four cancer cell lines. Mechanistic studies revealed that PPD25 significantly reduced the expression of beta-catenin, a key mediator in the Wnt pathway, as well as transcriptional targets of beta-catenin, namely c-myc, cyclin D1, cdk4 and T cell factor (TCF)-4. In addition, beta-catenin/TCF transcriptional activity was significantly suppressed by PPD25. 4. The data demonstrate that the PPD25 exerts its anticancer effect by targetting beta-catenin signalling, suggesting that PPD25 may have potential as a chemotherapeutic and/or chemopreventive agent for colon and lung cancer.

Dietary calcium and cholecalciferol modulate cyclin D1 expression, apoptosis, and tumorigenesis in intestine of adenomatous polyposis coli1638N/+ mice.

Both epidemiological and experimental findings have indicated that components of Western diets influence colonic tumorigenesis. Among dietary constituents, calcium and cholecalciferol have emerged as promising chemopreventive agents. We have demonstrated that a Western-style diet (WD) with low levels of calcium and cholecalciferol and high levels of (n-6) PUFA, increased the incidence of neoplasia in mouse intestine compared with a standard AIN-76A diet; models included wild-type mice and mice with targeted mutations. In the present study, adenomatous polyposis coli (Apc)(1638N/+) mice carrying a heterozygous Apc mutation were fed either an AIN-76A diet, a WD, or a WD supplemented with calcium and cholecalciferol (WD/Ca/VitD3). Diets were fed for 24 wk and effects on cellular and molecular events were assessed by performing immunohistochemistry in colonic epithelium along the crypt-to-surface continuum. Feeding WD to Apc(1638N/+) mice not only enhanced cyclin D1 expression in colonic epithelium compared with AIN-76A treatment as previously reported but also significantly increased the expression of the antiapoptotic protein B-cell lymphoma 2 (Bcl-2) concomitantly with a decrease in the proapoptotic Bcl2-associated X protein and the number of apoptotic epithelial cells. WD treatment enhanced mutant Apc-driven small intestinal carcinogenesis and also resulted in the formation of a small number of colonic adenomas (0.16 +/- 0.09; P < 0.05). By contrast, the WD/Ca/VitD3 diet reversed WD-induced growth, promoting changes in colonic epithelium. Importantly, Apc(1638N/+) mice fed the WD/Ca/VitD3 diet did not develop colonic tumors, further indicating that dietary calcium and cholecalciferol have a key role in the chemoprevention of colorectal neoplasia in this mouse model of human colon cancer.