99Tc-MDP 对OPG/RANKL/RANK系统在颌骨成釉细胞瘤中的调节机制研究

Jaw ameloblastoma (Ameloblastoma, AM) is the most common odontogenic tumors in the oral and maxillofacial region, accounted for more than 60% odontogenic tumors. AM is benign, but with local aggressive characteristics that severely affect the quality of life of patients after radical resection, particularly in young patients. On the contrary, the bone continuity can be maintained if conservative treatment including marsupialization and curettage is performed in AM, but easy to relapse after operation, the recurrence rate ranged from 17% up to 38% in unicystic and multicystic ameloblastoma entity type, respectively. Therefore, how to control AM recurrence after the conservative treatment is the challenge for the oral and maxillofacial surgeons. According to the previous literatures, OPG/RANKL/RANK system is regulated by bisphosphonates through osteoclasts, and many diseases related to bone resorption, which was mediated by osteoclasts, can also be significantly controlled by bisphosphonates. Moreover, OPG/RANKL/RANK system also plays a key role in the development of AM, it has resorption characteristics. Our previous study found that technetium-99m methylene diphosphonate (99Tc-MDP) concentrated in all lesions of the jaw AM among the newly patients and recurrent patients following the conservative treatment. Based on the above considerations, we hypothesize that 99Tc-MDP owns some effects on OPG/RANKL/RANK system and therapeutic action in AM. To confirm the hypothesis, we will explore that the effect of 99Tc-MDP on OPG, RANKL and RANK in AM through AM cell, RAW264.7 cell strains and skull bone cell strains in vitro, and removal teeth model in SD mice, explore the relationship between 99Tc-MDP dose and both osteoblasts and osteoclasts, and analysize phosphorus elements of content and the distribution comparation in order to reveal jaw absorption mechanism in AM. Our results may provide the theoretical basis for the conservative treatment of AM.

文献报道二磷酸盐通过破骨细胞对OPG/RANKL/RANK系统调控,对其引起的相关性骨吸收疾病有治疗作用。OPG/RANKL/RANK系统在颌骨成釉细胞瘤(Ameloblastoma, AM)发展过程中起重要作用，AM也具有骨吸收特性。我们前期研究发现所有行锝亚甲基二磷酸盐(99Tc-MDP)核素扫描的AM患者，病变部位均显示99Tc-MDP浓聚。因此我们推测99Tc-MDP对AM中OPG/RANKL/RANK系统具有影响，对AM可能有治疗作用。本课题拟通过细胞培养及SD大鼠拔牙创模型，观测99Tc-MDP对AM细胞、破骨细胞前体RAW264.7细胞和人颅骨成骨细胞及颌骨拔牙创愈合的影响，探讨99Tc-MDP对成骨细胞和破骨细胞影响的正负关系，分析颌骨中磷等元素的含量及分布比，以期揭示99Tc-MDP对OPG、RANKL及RANK在AM中的骨吸收机制，为开窗刮治的方法治疗AM提供依据。

颌骨成釉细胞瘤(Ameloblastoma, AM)是口腔颌面部最常见的牙源性肿瘤。AM虽为良性肿瘤,但具有局部侵袭性特点，治疗以外科手术根治切除为主，但术后严重影响患者的生活质量，尤其是青少年患者。近年国内外学者用开窗刮治的方法治疗AM，可以保留颌骨的连续性，取得了明显的临床疗效，但术后容易复发，在单囊型与实体型和多囊型中，其复发率分别高达17%和38%，而根治切除术复发率分别仅为4%和8%。因此，如何降低开窗刮治术后AM的复发率是口腔颌面外科医师面临的难题。AM开窗刮治术后复发不仅与未能完全刮除肿瘤有关，也与其侵袭性生长特性相关，该特性必然同时伴随周围骨质的破坏吸收。在该过程中OPG/RANKL/RANK系统对破骨细胞分化、成熟起到至关重要的作用，二膦酸盐对OPG/RANKL/RANK系统具有调控作用，可明显的抑制破骨细胞。本课题通过临床标本观测颌骨成釉细胞瘤中OPG、RANKL及RANK蛋白的表达情况，包括术前行锝亚甲基二磷酸盐(99mTc-MDP)核素扫描的患者标本，探讨OPG、RANKL、RANK的表达与颌骨成釉细胞瘤开窗刮治术后复发之间的关系。通过体内外实验，探讨99Tc-MDP对OPG、RANKL、RANK表达的影响以及99Tc-MDP和唑来膦酸剂量对成骨和破骨细胞影响的正负关系，明确安全使用剂量。 在本研究中，核素扫描均显示颌骨成釉细胞瘤病变部位99mTc-MDP浓聚。本项目初步证明99mTc-MDP核素在所有颌骨相关破骨细胞引起的骨吸收性病变中均显影浓聚。黄磷性颌骨骨髓炎和二膦酸盐颌骨骨髓炎二者临床表现极为相似，病变组织细微结构和主要成分也相似，这为99Tc-MDP（云克）治疗颌骨成釉细胞瘤时预防并发症提供临床依据。体外研究表明99Tc-MDP对RAW264.7细胞有抑制作用，且随浓度和作用时间的增加而增大，诱导其凋亡和降低RANK的表达。低浓度99Tc-MDP对MC3T3-E1细胞作用有促增值作用，并增加OPG 和RANKL的表达。该研究为99Tc-MDP治疗颌骨成釉细胞瘤提供了理论依据临床依据，99Tc-MDP对AM中OPG/RANKL/RANK系统具有调控作用，使用开窗刮治保守方法术治疗颌骨AM，再辅以二磷酸盐类药物，可防治术后复发。另外，该研究也为99Tc-MDP治疗其它相关破骨细胞引起的颌骨骨吸收性病变提供临床依据，如SAPHO综合征等