Relationship between MLH1, PMS2, MSH2 and MSH6 gene-specific alterations and tumor mutational burden in 1057 microsatellite instability-high solid tumors

Microsatellite instability-high (MSI-H) and tumor mutational burden (TMB) are predictive biomarkers for immune-checkpoint inhibitors (ICIs). Still, the relationship between the underlying cause(s) of MSI and TMB in tumors remains poorly defined. We investigated associations of TMB to mismatch repair (MMR) protein expression patterns by immunohistochemistry (IHC) and MMR mutations in a diverse sample of tumors. Hypothesized differences were identified by the protein/gene affected/mutated and the tumor histology/primary site. Overall, 1057 MSI-H tumors were identified from the 32 932 tested. MSI was examined by NGS using 7000+ target microsatellite loci. TMB was calculated using only nonsynonymous missense mutations sequenced with a 592-gene panel; a subset of MSI-H tumors also had MMR IHC performed. Analyses examined TMB by MMR protein heterodimer impacted (loss of MLH1/PMS2 vs. MSH2/MSH6 expression) and gene-specific mutations. The sample was 54.6% female; mean age was 63.5 years. Among IHC tested tumors, loss of co-expression of MLH1/PMS2 was more common (n = 544/705, 77.2%) than loss of MSH2/MSH6 (n = 81/705, 11.5%; P < .0001), and was associated with lower mean TMB (MLH1/PMS2: 25.03 mut/Mb vs MSH2/MSH6 46.83 mut/Mb; P < .0001). TMB also varied by tumor histology: colorectal cancers demonstrating MLH1/PMS2 loss had higher TMBs (33.14 mut/Mb) than endometrial cancers (20.60 mut/Mb) and other tumors (25.59 mut/Mb; P < .0001). MMR gene mutations were detected in 42.0% of tumors; among these, MSH6 mutations were most common (25.7%). MSH6 mutation patterns showed variability by tumor histology and TMB. TMB varies by underlying cause(s) of MSI and tumor histology; this heterogeneity may contribute to differences in response to ICI.     

Managing the cervical spine in multiple myeloma patients

Discuss the relevant literature on surgical and nonsurgical treatments for multiple myeloma (MM) and their complementary effects on overall treatment. Existing surgical algorithms designed for neoplasia of the spine may not suit the management of spinal myeloma. Less than a fifth of metastatic, including myelomatous lesions, occur in the cervical spine but have a poorer prognosis and surgery in this area carries a higher morbidity. With the advances of chemotherapy, early access to radiotherapy, early orthosis management, and high definition imaging, including CT and MRI, surgical indications in MM have changed. Medical decompression (or oncolysis), including in the presence of neurological deficit and orthotic stabilization, are proving viable nonsurgical options to manage MM. A key to decision making is the assessment and monitoring of biomechanical spinal stability as part of a multidisciplinary approach.     

Surgical management of the rheumatoid hand and wrist

Management of the patient with rheumatoid arthritis of the hand and wrist demands a methodical approach. Multidisciplinary assessment and treatment in conjunction with a rheumatologist and dedicated hand therapist are essential. Initial treatment should be conservative. However, when patients develop severe deformities refractory to medical treatment, or there is impending tendon rupture or nerve compression, surgical intervention is required. This article aims to provide a current review of the principles and common conditions in surgery for rheumatoid arthritis of the hand and wrist.     

扁塑藤素调控Notch信号通路诱导人肺癌条件重编程细胞死亡的作用机制研究

目的：应用条件性重编程细胞（conditionally reprogrammed cells，CRCs）技术建立人肺癌细胞体外长期培养体系，研究扁塑藤素对人肺癌CRCs增殖和迁移能力的影响，并探讨相关作用机制。方法：免疫组化法检测Notch 1、HES1和Cyclin D3在肿瘤组织和癌旁组织中的表达水平；使用CRCs技术分离培养非小细胞肺癌原代细胞；使用2，4，8，16 μmol·L^-1的扁塑藤素处理人肺癌CRCs，MTS法检测细胞活力，Annexin V/PI流式细胞术检测细胞凋亡，Transwell法检测细胞迁移能力，Western Blot检测细胞中Notch信号通路相关蛋白Notch 1、HES1和Cyclin D3的表达水平。结果：在非小细胞肺癌患者肿瘤组织中Notch 1、HES1和Cyclin D3的表达水平高于癌旁组织；扁塑藤素能够诱导人肺癌CRCs死亡，并在一定范围内呈现时间和浓度依赖性（P<0.05）；随着扁塑藤素作用浓度的增高，人肺癌CRCs凋亡率明显增高（P<0.05），细胞迁移能力下降（P<0.05）；扁塑藤素能够下调人肺癌CRCs中Notch 1、HES1和Cyclin D3的蛋白表达水平。结论：扁塑藤素可能通过调控Notch信号通路相关蛋白的表达水平，抑制人肺癌CRCs的增殖和迁移，并诱导其凋亡，为肺癌的治疗提供新的实验数据和理论依据。