Differentially Expressed Transcripts and Dysregulated Signaling Pathways and Networks in African American Breast Cancer

<div><p>African Americans (AAs) have higher mortality rate from breast cancer than that of Caucasian Americans (CAs) even when socioeconomic factors are accounted for. To better understand the driving biological factors of this health disparity, we performed a comprehensive differential gene expression analysis, including subtype- and stage-specific analysis, using the breast cancer data in the Cancer Genome Atlas (TCGA). In total, 674 unique genes and other transcripts were found differentially expressed between these two populations. The numbers of differentially expressed genes between AA and CA patients increased in each stage of tumor progression: there were 26 in stage I, 161 in stage II, and 223 in stage III. Resistin, a gene that is linked to obesity, insulin resistance, and breast cancer, was expressed more than four times higher in AA tumors. An uncharacterized, long, non-coding RNA, LOC90784, was down-regulated in AA tumors, and its expression was inversely related to cancer stage and was the lowest in triple negative AA breast tumors. Network analysis showed increased expression of a majority of components in p53 and BRCA1 subnetworks in AA breast tumor samples, and members of the aurora B and polo-like kinase signaling pathways were also highly expressed. Higher gene expression diversity was observed in more advanced stage breast tumors suggesting increased genomic instability during tumor progression. Amplified resistin expression may indicate insulin-resistant type II diabetes and obesity are associated with AA breast cancer. Expression of LOC90784 may have a protective effect on breast cancer patients, and its loss, particularly in triple negative breast cancer, could be having detrimental effects. This work helps elucidate molecular mechanisms of breast cancer health disparity and identifies putative biomarkers and therapeutic targets such as resistin, and the aurora B and polo-like kinase signaling pathways for treating AA breast cancer patients. </p> </div

LOC90784, a long non-coding RNA, was differentially expressed across comparisons of African- and Caucasian-American tumors.

<p>The expression of this transcript was consistent in CA tumors, but its expression was inversely related to stage and was lowest in AA with TNBC. P-values for the comparisons were overall: 1.46E-14, luminal A: 1.98E-04, stage I: 6.61E-04, stage II: 3.63E-08, stage III: 2.57E-05, and triple negative: 1.86E-09 (see Supplementary Tables). Error bars are standard error.</p

A flowchart summarizing the data analysis methodology.

<p>A flowchart summarizing the data analysis methodology.</p

A new synthetic matrix metalloproteinase inhibitor reduces human mesenchymal stem cell adipogenesis.

Development of adipose tissue requires the differentiation of less specialized cells, such as human mesenchymal stem cells (hMSCs), into adipocytes. Since matrix metalloproteinases (MMPs) play critical roles in the cell differentiation process, we conducted investigations to determine if a novel mercaptosulfonamide-based MMP inhibitor (MMPI), YHJ-7-52, could affect hMSC adipogenic differentiation and lipid accumulation. Enzyme inhibition assays, adipogenic differentiation experiments, and quantitative PCR methods were employed to characterize this inhibitor and determine its effect upon adipogenesis. YHJ-7-52 reduced lipid accumulation in differentiated cells by comparable amounts as a potent hydroxamate MMPI, GM6001. However, YHJ-7-82, a non-inhibitory structural analog of YHJ-7-52, in which the zinc-binding thiol group is replaced by a hydroxyl group, had no effect on adipogenesis. The two MMPIs (YHJ-7-52 and GM6001) were also as effective in reducing lipid accumulation in differentiated cells as T0070907, an antagonist of peroxisome-proliferator activated receptor gamma (PPAR-gamma), at a similar concentration. PPAR-gamma is a typical adipogenic marker and a key regulatory protein for the transition of preadiopocyte to adipocyte. Moreover, MMP inhibition was able to suppress lipid accumulation in cells co-treated with Troglitazone, a PPAR-gamma agonist. Our results indicate that MMP inhibitors may be used as molecular tools for adipogenesis and obesity treatment research

Venn diagram depicting overlap of differentially expressed genes and other transcripts between stage-matched African- and Caucasian-American tumors.

<p>Increases or decreases indicate AA gene expression and are relative to CA expression. Gene names: FYCO1 - FYVE and coiled-coil domain containing 1; LOC90784 - Not Available; LOC285359 - Not Available; LRRC37A2 - leucine rich repeat containing 37, member A2; MEIS3P1 - Meis homeobox 3 pseudogene 1; NOTCH2NL - notch 2 N-terminal like; PRSS45 - protease, serine, 45.</p

Differentially expressed subnetworks identified by Gene Expression Network Analysis.

<p>Subnetworks containing p53 (A) and BRCA1 (B) were differentially expressed in AA tumors. Subnetworks were identified using GXNA and visualized using STRING. Starred results were not differentially expressed but were included in the subnetwork by GXNA. Values in parentheses are the mean fold changes of log₂-transformed AA expression relative to CA expression, calculated as log₂(CA)/log₂(AA). Gene names: HMGB2: BRCA1 - breast cancer 1, early onset; CCNB2 - cyclin B2; CDC25B - cell division cycle 25B; CDK1 - cyclin-dependent kinase 1; CKS2 - CDC28 protein kinase regulatory subunit 2; ELAVL1 - ELAV (embryonic lethal, abnormal vision, Drosophila)-like 1 (Hu antigen R); FANCA - Fanconi anemia, complementation group A; HMGB2 - high mobility group box 2; HSF1 - heat shock transcription factor 1; HSPA8 - heat shock 70kDa protein 8; PKMYT1 - protein kinase, membrane. associated tyrosine/threonine 1; PML - promyelocytic leukemia; PPP1R13L - protein phosphatase 1, regulatory subunit 13 like; PTMA - prothymosin, alpha; RAD50 - RAD50 homolog (S. cerevisiae); RAD51 - RAD51 recombinase; TP53 - tumor protein p53; TXN – thioredoxin.</p

Co-treatment of differentiating hMSCs with T0070907 and MMPIs.

<p>(A) Cells undergoing differentiation in the presence of 10 <i>μ</i>M T0070907 were co-treated with either 10 <i>μ</i>M YHJ-7-82, YHJ-7-52, or GM6001. DMSO vehicle was maintained consistent between treatments and used as control. (B) Relative cell number was determined via nuclei counts. Results are displayed as mean ± standard error. Scale bar 150 μm. ** <i>P</i> < 0.05, ++ <i>P</i> < 0.05, ## <i>P</i> < 0.05 compared to T0070907.</p

Co-treatment of differentiating hMSCs with Troglitazone and MMPIs.

<p>Cells undergoing differentiation in the presence of 10 <i>μ</i>M Troglitazone were co-treated with either 10 <i>μ</i>M YHJ-7-82, YHJ-7-52, or GM6001. DMSO vehicle was maintained consistent between treatments and used as control. Results are displayed as mean ± standard error. Scale bar 150 μm. ** <i>P</i> < 0.05.</p

The impact of baseline serum C-reactive protein and C-reactive protein kinetics on the prognosis of metastatic nasopharyngeal carcinoma patients treated with palliative chemotherapy.

BACKGROUND:The aim of this study was to determine whether baseline C-reactive protein (CRP) levels and CRP kinetics predict the overall survival in metastatic nasopharyngeal carcinoma (mNPC) patients. METHODS:A total of 116 mNPC patients from January 2006 to July 2011 were retrospectively reviewed. Serum CRP level was measured at baseline and thereafter at the start of each palliative chemotherapy cycle for all patients. RESULTS:Patients with higher values of baseline CRP (≥ 3.4 mg/L) had significantly worse survival than those with lower baseline CRP values (< 3.4 mg/L). Patients were divided into four groups according to baseline CRP and CRP kinetics: (1) patients whose CRP < 3.4 mg/L and never elevated during treatment; (2) patients whose CRP < 3.4 mg/L and elevated at least one time during treatment; (3) patients whose CRP ≥ 3.4 mg/L and normalized at least one time during treatment; and (4) patients whose CRP ≥ 3.4 mg/L and never normalized during treatment. The patients were further assigned to non-elevated, elevated, normalized, and non-normalized CRP groups. Overall survival rates were significantly different among the four groups, with three-year survival rates of 68%, 41%, 33%, and 0.03% for non-elevated, elevated, normalized, and non-normalized CRP groups respectively. When compared with the non-elevated group, hazard ratios of death were 1.69, 2.57, and 10.34 in the normalized, elevated, and non-normalized groups (P < 0.001). CONCLUSIONS:Baseline CRP and CRP kinetics may be useful to predict the prognosis of metastatic NPC patients treated with palliative chemotherapy and facilitate individualized treatment. A prospective study to validate this prognostic model is still needed however

Quantitative real-time PCR to measure gene expression levels of select adipogenic markers and MMPs in hMSCs induced toward an adipogenic linage.

<p>Human MSCs were treated with either YHJ-7-52 (10 <i>μ</i>M) or DMSO control. Expression of (A) PPARγ, (B) MMP-2, and (C) MMP-14 over time. Results are displayed as mean ± standard error. ** <i>P</i> < 0.05</p