Wang Jun, Shidfar Ali, Ivancic David, Ranjan Manish, Liu Liannian, Choi Mi-Ran, Parimi Vamsi, Gursel Demirkan B, Sullivan Megan E, Najor Matthew S, Abukhdeir Abde M, Scholtens Denise, Khan Seema A
Department of Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL.
Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL.
Int J Cancer. 2017 Jun 1;140(11):2484-2497. doi: 10.1002/ijc.30680. Epub 2017 Mar 21.
Risk biomarkers for estrogen receptor (ER)-negative breast cancer have clear value for breast cancer prevention. We previously reported a set of lipid metabolism (LiMe) genes with high expression in the contralateral unaffected breasts (CUBs) of ER-negative cancer cases. We now further examine LiMe gene expression in both tumor and CUB, and investigate the role of Pre-B-cell leukemia homeobox-1 (PBX1) as a candidate common transcription factor for LiMe gene expression. mRNA was extracted from laser-capture microdissected epithelium from tumor and CUB of 84 subjects (28 ER-positive cases, 28 ER-negative cases, 28 healthy controls). Gene expression was quantitated by qRT-PCR. Logistic regression models were generated to predict ER status of the contralateral cancer. Protein expression of HMGCS2 and PBX1 was measured using immunohistochemistry. The effect of PBX1 on LiMe gene expression was examined by overexpressing PBX1 in MCF10A cells with or without ER, and by suppressing PBX1 in MDA-MB-453 cells. The expression of DHRS2, HMGCS2, UGT2B7, UGT2B11, ALOX15B, HPGD, UGT2B28 and GLYATL1 was significantly higher in ER-negative versus ER-positive CUBs, and predicted ER status of the tumor in test and validation sets. In contrast, LiMe gene expression was significantly lower in ER-negative than ER-positive tumors. PBX1 overexpression in MCF10A cells up-regulated most LiMe genes, but not in MCF10A cells overexpressing ER. Suppressing PBX1 in MDA-MB-453 cells resulted in decrease of LiMe gene expression. Four binding sites of PBX1 and cofactor were identified in three lipid metabolism genes using ChIP-qPCR. These data suggest a novel role for PBX1 in the regulation of lipid metabolism genes in benign breast, which may contribute to ER-negative tumorigenesis.
雌激素受体（ER）阴性乳腺癌的风险生物标志物对乳腺癌预防具有明确价值。我们之前报道了一组在ER阴性癌症病例的对侧未受影响乳房（CUB）中高表达的脂质代谢（LiMe）基因。我们现在进一步检测肿瘤和CUB中LiMe基因的表达，并研究前B细胞白血病同源盒1（PBX1）作为LiMe基因表达的候选共同转录因子的作用。从84名受试者（28例ER阳性病例、28例ER阴性病例、28例健康对照）的肿瘤和CUB的激光捕获显微切割上皮中提取mRNA。通过qRT-PCR对基因表达进行定量。生成逻辑回归模型以预测对侧癌症的ER状态。使用免疫组织化学检测HMGCS2和PBX1的蛋白表达。通过在有或无ER的MCF10A细胞中过表达PBX1以及在MDA-MB-453细胞中抑制PBX1来检测PBX1对LiMe基因表达的影响。在ER阴性的CUB中，DHRS2、HMGCS2、UGT2B7、UGT2B11、ALOX15B、HPGD、UGT2B28和GLYATL1的表达显著高于ER阳性的CUB，并在测试和验证集中预测了肿瘤的ER状态。相比之下，ER阴性肿瘤中LiMe基因表达显著低于ER阳性肿瘤。在MCF10A细胞中过表达PBX1可上调大多数LiMe基因，但在过表达ER的MCF10A细胞中则不然。在MDA-MB-453细胞中抑制PBX1导致LiMe基因表达下降。使用ChIP-qPCR在三个脂质代谢基因中鉴定出PBX1及其辅因子的四个结合位点。这些数据表明PBX1在良性乳腺脂质代谢基因调控中具有新作用，这可能有助于ER阴性肿瘤的发生。
