GLUCOSYLCERAMIDE SYNTHASE IN A NOVEL TARGET FOR CANCER TREATMENT

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 每年有超过50万美国人死于癌症，主要是由于化疗失败。肿瘤细胞的耐药性是化疗失败的生物学基础。癌症治疗的改善需要采用最先进的技术来确定逆转耐药性的靶点。葡糖神经酰胺合酶催化神经酰胺糖基化，将神经酰胺转化为葡糖神经酰胺。这一过程使神经酰胺诱导的细胞凋亡失活，而细胞凋亡与抗癌药物的作用有关。我们的前期工作表明，GCS基因的过表达增强了肿瘤细胞对抗癌药物的耐药性，而反义基因转染阻断GCS基因表达可通过增强药物摄取和诱导凋亡来逆转肿瘤细胞的耐药性。假设GCS是癌症治疗的潜在靶点。最近，我们发现GCS在乳腺癌、卵巢癌、结肠癌、黑色素瘤和上皮癌等耐药细胞系中均存在过表达。通过使用反义寡核苷酸抑制GCS表达逆转了这些癌细胞系中的阿霉素耐药性。与正常乳腺组织相比，GCS过度表达在超过70%的乳腺癌转移中检测到，而在纤维增生中未检测到。GCS过度表达在87%的淋巴结阳性和77%的ER阳性乳腺癌中检测到。白血病化疗无反应组GCS mRNA水平是完全反应组的2.4倍。硫代磷酸寡核苷酸抑制GCS基因选择性增敏乳腺癌细胞阿霉素。目前，我们正在研究第二代寡核苷酸，包括混合骨架寡核苷酸，锁核酸，旨在开发一种有效的药物来逆转耐药性，改善体内化疗。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. More than 500,000 Americans die every year from cancer, mostly due to a failure at their chemotherapy. Drug-resistance of cancer cells is the biological basis of chemotherapy failure. Improvement of cancer treatment requires adopting the state-of-art technologies to identify target for the reversal of drug-resistance. Glucosylceramide synthase catalyzes ceramide glycosylation, converting ceramide into glucosylceramide. This process deactivates ceramideinduced apoptosis which is involved in the action of anticancer drugs. Our previous works showed that enforced GCS overexpression conferred cancer cells resistance to anticancer drugs, and disrupting GCS gene expression with antisense gene transfection reversed drug resistance via enhancing drug-uptake and sensitizing apoptosis. It is hypothesized that GCS is a potential target for cancer treatment. Recently, we found that GCS overexpression is detected in drug-resistant cell lines including breast cancer, ovarian cancer, colon cancer, melanoma and epithelia cancer. Suppressing GCS expression by using antisense oligonucleotide reversed doxorubicin-resistance in these cancer cell lines. GCS overexpression was detected in more than 70% of metastasis of breast cancer, not detected in fibroplasias, compared to normal breast tissues. GCS overexpression is detected in 87% lymph nodes positive, and 77% ERpositive breast cancer samples. In chemotherapy of patients with leukemia, GCS mRNA levels in non-response group are 2.4-fold higher than that in complete-response group. Suppressing GCS gene by phosphorothioate oligonucleotide selectively sensitizes breast cancer cellsdoxorubicin. Currently, we are examining the second generation of oligonucleotides, including mixed-backbone oligonucleotide, locked nucleic acid, aiming to develop an effective agent to reverse drug-resistance and improve chemotherapy in vivo.