lncRNA BCAS1-4靶向维生素D代谢关键酶CYP24A1影响肿瘤细胞的增殖和迁移

Some observational, preclinical and clinical studies suggest that vitamin D deficiency increases the risk of developing multiple malignancies. A long non-coding RNA (lncRNA) can play a critical role in various biological functions and disease processes including cancer. However, there are few reports describing that lncRNA regulates vitamin D system on prevention and therapy of cancer. CYP24A is strongly induced by 1α,25 dihydroxyvitamin D [1α,25(OH)2D3] to produce the less active of vitamin D metabolites 1α,24,25(OH)2D3 and 24,25(OH)2D3. Our preliminary results showed that reduced CYP24A1 suppressed the proliferation and migration of ovarian cancer cells. We found that CYP24A1interacted with FUS by mediating ZEB1 to inhibit EMT of ovarian cancer cells. Interestingly, the level of lncBCAS1-4 was also raised up to 1491 fold after treated by 1α,25(OH)2D3. Both CYP24A1 and lncBCAS1-4 are located on 20q13.2 of chromosome 20. The full-length of lncBCAS1-4 is 320 nt, and 75% of it is consistent to sequence of CYP24A1. Moreover, reduced lncBCAS1-4 promotes the anti-proliferation and anti-migration in ovarian cancer cells. We propose that lncBCAS1-4 interacts with CYP24A1 to promote the anti-cancer function of vitamin D. Therefore, in the current project, we are aiming to systematically investigate the effects of lncBCAS1-4 on the proliferation and migration of lung and ovarian cancer cells. We plan to reveal the mechanism underlying the interaction of lncBCAS1-4 with CYP24A1. The patient tumor derived xenograft (PDX) and tumor tissue array will be used to verify that reduced lncBCAS1-4 can enhance the anti-tumor effect of 1α,25(OH)2D3. Our results will be expected to clarify that lncRNA may play a crucial role of vitamin D reducing cancer risk and progression.

维生素D与肿瘤的关系倍受关注，机制研究也逐渐深入。维生素D代谢酶CYP24A1不仅使活性维生素D降解、失活，课题组前期研究发现其还具有癌基因样作用，即增加CYP24A1表达促进卵巢癌细胞增殖和迁移；反之，则降低细胞增殖和迁移。长链非编码RNA(long non coding RNA, lncRNA)不仅参与肿瘤细胞调控编码基因的转录、翻译及修饰，也可能是肿瘤发生的标志物以及治疗靶点。课题组前期研究结果证实，活性维生素D处理后lncRNA BCAS1-4上调高达1491.58±519.42倍，与活性维生素D诱导CYP24A1上调（1127.452±893.32）的现象一样，对活性维生素D处理都非常敏感。lncRNA BCAS1-4位于染色体20q13.2，全长380 nt，其中75%序列与CYP24A1序列一致。lncRNA BCAS1-4的转录结构与CYP24A1非常相似。但是有关lncRNA BCAS1-4对肿瘤细胞增殖和迁移能力的影响及其调控的靶分子还没有报道，减少lncRNA BCAS1-4是否可以提高维生素D抗肿瘤效果，还需要在多种肿瘤细胞以及体内研究体系验证。为了解决这些科学问题，本课题选定两类肿瘤，即发病率最高也是癌症死因之首的肺癌细胞，以及女性病死率最高的卵巢癌细胞。从lncRNA BCAS1-4靶向维生素D代谢关键酶CYP24A1影响肺癌和卵巢癌细胞增殖和迁移展开研究。首先研究lncRNA BCAS1-4对肿瘤细胞增殖和迁移的影响，分析减少lncRNA BCAS1-4和CYP24A1提高活性维生素D抗肿瘤效果的异同点；利用lncRNA研究技术，研究lncRNA BCAS1-4与CYP24A1相互作用关系；最后通过PDX模型和人肿瘤组织等研究体系，评价BCAS1-4提高维生素D抗肿瘤效果，本项目有望揭示长链非编码RNA参与维生素D非经典作用的分子理论。

课题组前期实验结果发现，活性维生素D处理卵巢癌细胞后长链非编码RNA(long non coding RNA, lncRNA) CYP24A1-6_7上调高达1491.58±519.42倍。本研究证实lncCYP24A1-6_7具有癌基因样功能，过表达lncCYP24A1-6_7促进卵巢癌和肺癌细胞的增殖、迁移和侵袭；减少lncCYP24A1-6_7表达抑制肿瘤细胞增殖、迁移和侵袭。这可能与lncCYP24A1-6_7和肿瘤细胞磷酸戊糖途径的TKT、ALDOA酶、糖酵解途径的HK2、LDHA酶以及EMT相关蛋白Vimentin直接相互作用，并上调这些蛋白表达相关。进一步研究发现，lncCYP24A1-6_7减弱活性维生素D抑制卵巢癌和肺癌细胞增殖和迁移的作用。本研究发现lncCYP24A1-6_7拮抗活性维生素D的抗肿瘤作用，与其上调导致肿瘤细胞代谢酶升高无关，但是与EMT转录因子升高相关，其机制值得进一步探讨。lncCYP24A1-6_7位于染色体20q13.2，全长380 nt，和维生素D代谢酶CYP24A1的转录结构有75%相同序列，在肿瘤细胞内有相似表型，即癌基因样功能和部分拮抗活性维生素D抗肿瘤作用，但是两者作用机制并不完全一样。因此，设计lncCYP24A1-6_7的特异性抑制剂，以及组装在活性维生素D的纳米材料内，并靶向肿瘤细胞，有望提高维生素D抗肿瘤作用。