Regulation of miRNA expression in breast cancer cells

描述（由申请人提供）：选择性雌激素受体调节剂（SERM）他莫昔芬（TAM）是治疗和预防雌激素受体α（ER α）阳性乳腺癌的最广泛使用的内分泌疗法。然而，在辅助治疗的情况下，最初TAM敏感的肿瘤变得TAM耐药。这种获得性TAM耐药性背后的机制尚不清楚，TAM反应的生物标志物可能有助于监测临床反应。微小RNA（miRNAs）是一类天然存在的小的非编码RNA分子，其与小干扰RNA（siRNAs）相关但不同。miRNA参与调节mRNA的翻译和加工，通常通过与靶mRNA的3'非翻译区结合并靶向待降解的mRNA转录物。人类基因组被认为含有> 400个miRNA。最近，miRNA表达的异常模式与人乳腺癌有关，一项研究表明，miRNA的差异表达与乳腺癌分期和患者预后的其他公认标志物一致，包括ER α和孕酮受体表达、肿瘤分期、阳性淋巴结数量和血管浸润。然而，到目前为止，还没有人研究雌二醇（E2）或选择性ER调节剂/抗雌激素是否影响人类乳腺癌中的miRNA表达模式，或者miRNA表达模式是否与获得性抗雌激素耐药相关。具体目标1是鉴定在抗雌激素敏感的MCF-7乳腺癌细胞中由雌二醇（E2）和4-羟基他莫昔芬（4-OHT）调节的miRNA。目的1验证E2和4-OHT对人乳腺癌细胞中miRNAs表达的差异调节作用。此外，我们认为这些miRNAs反过来调节基因编码的蛋白质参与分化和细胞增殖的mRNA的稳定性。特异性目的2检验了miRNA表达在抗雌激素/TAM耐药与敏感乳腺癌细胞中失调的假设。具体目标3是确定在乳腺癌细胞系中鉴定的E2调节的和4-OHT调节的miRNA是否在人乳腺肿瘤中显示异常表达并与患者对他莫昔芬治疗的反应相关。我们长期希望miRNAs能够为乳腺肿瘤获得TAM/抗雌激素耐药并成为侵袭性和转移性的机制提供新的生物标志物和新的见解。

DESCRIPTION (provided by applicant): The selective estrogen receptor modulator (SERM) tamoxifen (TAM) is the most widely used endocrine therapy for the treatment and prevention of estrogen receptor alpha (ERalpha) positive breast cancer. With adjuvant therapy, however, initially TAM-sensitive tumors become TAM-resistant. The mechanism behind such acquired TAM resistance is unknown and biomarkers of TAM-response may be useful to monitor clinical response. MicroRNAs (miRNAs) are a class of naturally-occurring, small, non-coding RNA molecules that are related to, but distinct from, small interfering RNAs (siRNAs). miRNAs are involved in regulating the translation and processing of mRNAs, usually by binding to the 3' untranslated region of target mRNAs and targeting the mRNA transcript to be degraded. The human genome is thought to contain > 400 miRNAs. Abberant patterns of miRNA expression have been recently implicated in human breast cancer and one study showed that miRNAs were differentially expressed in concordance with other well-established markers of breast cancer stage and patient prognosis including ERalpha and progesterone receptor expression, tumor stage, number of positive lymph nodes, and vascular invasion. However, to date, no one has examined whether estradiol (E2) or selective ER modulators/antiestrogens affect the pattern of miRNA expression in human breast cancer or whether miRNA expression patterns correlate with acquired antiestrogen-resistance. Specific Aim 1 is to identify miRNAs that are regulated by estradiol (E2) and 4-hydroxytamoxifen (4-OHT) in antiestrogen-sensitive MCF-7 breast cancer cells. Aim 1 tests the hypothesis that E2 and 4-OHT differentially regulate the expression of miRNAs in human breast cancer cells. Further, we suggest these miRNAs in turn regulate the mRNA stability of genes encoding proteins involved in differentiation and cell proliferation. Specific Aim 2 tests the hypothesis that miRNA expression is dysregulated in antiestrogen/TAM-resistant versus -sensitive breast cancer cells. Specific Aim 3 is to determine if the E2-regulated and 4-OHT-regulated miRNAs identified in breast cancer cell lines show aberrant expression in human breast tumors and correlate with patient response to tamoxifen therapy. It is our long term hope that miRNAs may provide novel biomarkers and new insights into the mechanisms by which breast tumors gain TAM/antiestrogen-resistance and become invasive and metastatic.