BACKGROUND The pathological complete response(ypCR)rate following neoadjuvant chemotherapy for advanced gastric cancer remains low and lacks a universally accepted treatment protocol.Immunotherapy has achieved breakth...BACKGROUND The pathological complete response(ypCR)rate following neoadjuvant chemotherapy for advanced gastric cancer remains low and lacks a universally accepted treatment protocol.Immunotherapy has achieved breakthrough progress.CASE SUMMARY We report two female patients with gastric cancer defined as clinical stage cT4N1-2M0.Detection of mismatch repair protein showed mismatch repair function defect,and perioperative treatment with programmed death protein 1 inhibitor combined with S-1+oxaliplatin achieved ypCR.Surprisingly,the patients underwent clinical observation after surgery but developed different degrees of metastasis at~6 mo after surgery.CONCLUSION PD-1 inhibitor combined with chemotherapy provides a more strategic choice for comprehensive perioperative treatment of gastric cancer.展开更多
The MutS protein plays an important role in the DNA mismatch repair system. Mutations in the mutS gene can lead to genome instability and ultimately cell malfunction. Here we have established a method for identifying ...The MutS protein plays an important role in the DNA mismatch repair system. Mutations in the mutS gene can lead to genome instability and ultimately cell malfunction. Here we have established a method for identifying functional defective mutants of MutS by random mutation and rifampicin screening. Some novel functional sites in MutS were identified. The MutS mutant strains were analyzed using surface plasmon resonance, gel filtration and far-western methods to determine the molecular mechanisms behind the DNA mismatch repair function of MutS.展开更多
Functional deficiency of mismatch repair(MMR) system is one of the mechanisms of tumorigenesis.With the development of the investigation and the requirement from the clinical diagnosis and treatment it is necessary to...Functional deficiency of mismatch repair(MMR) system is one of the mechanisms of tumorigenesis.With the development of the investigation and the requirement from the clinical diagnosis and treatment it is necessary to build up a method to evaluate the functional status of the whole MMR system in the concerned tumors. The original ssDNA and dsDNA from wild type (wt) bacteriophage M13mp2 and its three derivates with mutation points in the lacZa gene have been used to construct two kinds of heteroduplex DNA molecules. One named del(2) has two bases deleted in the negative strand, the other has a G-G mismatch base pair in the negative strand too. Introducing this heteroduplex DNA into E. coli NR9162 (routS^-) without the MMR ability on the indicator plate with x-gal and IPTG,there are three kinds of plaques, mixture plaque as the charaeteristie phenotype of heteroduplex DNA, blue and clearplaques. If the cell extract is mismatch repair competent the percentage of the mixture plaque will decrease after incubation with these heteroduplex DNA, the repair efficiency is expressed in percentage as 100x (1 minus the ratio of percentages of mixture plaque obtained from the extract-treated sample and untreated samples), which can imply the functionai status of MMR system of certain samples. After large T-antigen-dependent SV-40 DNA replication assay cell extract from TK6, a human lymphoblastoid B-cell lymphoma cell line with MMR ability, and Lovo, a human colonic carcinoma cell line with MMR deficiency have incubated with these heteroduplex DNA. The repair efficiency of TK6 to del(2) is more than 60%, to G-G is more than 50%. The Lovo efficiency to del(2) is less than 10%, to G-G is less than 20%.Therefore, in this in vitro model used for functional analysis of mismatch repair of heteroduplex DNA as the repair target,TK6 can serve as the control for MMR proficiency and Lovo as the control for MMR deficiency. Using this model the tumor tissue from a case of hereditary nonpolyposis colorectal cancer (microsatellite instability high, MSI-H) was measured and lack of MMR ability was shown. And a case of sporadic rectal cancer (SRC) (mierosatellite stability, MSS) maintains MMR proficiency. The results indicate that the model is sensitive and dependable. It could be used to measure the funetion status of MMR system in tumor cell and/or tissues. This is a reliable method to investigate the mechanic of tumorigenesis. It is meaningful in the observation of the role of MMR in the initiation and progression of concerned tumors.展开更多
1文献来源Le D T,Kim T W,Van Cutsem E,et al.PhaseⅡopen⁃label study of pembrolizumab in treatment⁃refractory,microsatellite instability⁃high/mismatch repair⁃deficient metastatic colorectal cancer:KEYNOTE⁃164[J].J Clin ...1文献来源Le D T,Kim T W,Van Cutsem E,et al.PhaseⅡopen⁃label study of pembrolizumab in treatment⁃refractory,microsatellite instability⁃high/mismatch repair⁃deficient metastatic colorectal cancer:KEYNOTE⁃164[J].J Clin Oncol,2019,38(1):11-19.2证据水平2a。3背景•微卫星高度不稳定性(microsatellite instability high,MSI⁃H)或错配修复功能缺陷(mismatch repair⁃deficient,dMMR)结直肠癌患者的预后比微卫星稳定(microsatellite stability,MSS)结直肠癌患者的预后差。展开更多
免疫检查点抑制剂的出现,增加了许多实体肿瘤的治疗选择。尽管在黑素瘤和肺癌的治疗中效果良好,但大多数转移性结直肠癌患者无法从免疫治疗中获益。免疫检查点抑制剂在错配修复功能缺失转移性结直肠癌患者中明确有显著和持久的临床反应...免疫检查点抑制剂的出现,增加了许多实体肿瘤的治疗选择。尽管在黑素瘤和肺癌的治疗中效果良好,但大多数转移性结直肠癌患者无法从免疫治疗中获益。免疫检查点抑制剂在错配修复功能缺失转移性结直肠癌患者中明确有显著和持久的临床反应,即使在既往多线治疗失败的群体中也是如此。然而,这种临床获益仅限于小部分肿瘤患者,约占转移性结直肠癌的4%。事实上抗程序性死亡受体1(programmed cell death protein 1,PD-1)单抗对错配修复功能缺失转移性结直肠癌患者是无效的。迫切需要新颖的治疗策略使这些肿瘤具有免疫应答。破坏肿瘤的疗法(化学疗法,放射疗法和靶向疗法),从而释放肿瘤抗原,是免疫检查点抑制和其他疗法相结合的最直接的策略。这些标准疗法远没有像曾经担心的那样削弱免疫反应,反而还可以增强免疫应答。展开更多
基金Supported by This work was sponsored by Tianjin Key Medical Discipline(Specialty)Construction Project,No.TJYXZDXK-035ATianjin Science and Technology Project,No.21JCYBJC01590.
文摘BACKGROUND The pathological complete response(ypCR)rate following neoadjuvant chemotherapy for advanced gastric cancer remains low and lacks a universally accepted treatment protocol.Immunotherapy has achieved breakthrough progress.CASE SUMMARY We report two female patients with gastric cancer defined as clinical stage cT4N1-2M0.Detection of mismatch repair protein showed mismatch repair function defect,and perioperative treatment with programmed death protein 1 inhibitor combined with S-1+oxaliplatin achieved ypCR.Surprisingly,the patients underwent clinical observation after surgery but developed different degrees of metastasis at~6 mo after surgery.CONCLUSION PD-1 inhibitor combined with chemotherapy provides a more strategic choice for comprehensive perioperative treatment of gastric cancer.
基金supported by the National Natural Science Foundation of China (Grant No. 30670443)the Chinese Academy of Sciences (Grant Nos. KSCX1-YW-R-63, KSCX2-YW-G-017 and KZCX2-YW-420)
文摘The MutS protein plays an important role in the DNA mismatch repair system. Mutations in the mutS gene can lead to genome instability and ultimately cell malfunction. Here we have established a method for identifying functional defective mutants of MutS by random mutation and rifampicin screening. Some novel functional sites in MutS were identified. The MutS mutant strains were analyzed using surface plasmon resonance, gel filtration and far-western methods to determine the molecular mechanisms behind the DNA mismatch repair function of MutS.
文摘Functional deficiency of mismatch repair(MMR) system is one of the mechanisms of tumorigenesis.With the development of the investigation and the requirement from the clinical diagnosis and treatment it is necessary to build up a method to evaluate the functional status of the whole MMR system in the concerned tumors. The original ssDNA and dsDNA from wild type (wt) bacteriophage M13mp2 and its three derivates with mutation points in the lacZa gene have been used to construct two kinds of heteroduplex DNA molecules. One named del(2) has two bases deleted in the negative strand, the other has a G-G mismatch base pair in the negative strand too. Introducing this heteroduplex DNA into E. coli NR9162 (routS^-) without the MMR ability on the indicator plate with x-gal and IPTG,there are three kinds of plaques, mixture plaque as the charaeteristie phenotype of heteroduplex DNA, blue and clearplaques. If the cell extract is mismatch repair competent the percentage of the mixture plaque will decrease after incubation with these heteroduplex DNA, the repair efficiency is expressed in percentage as 100x (1 minus the ratio of percentages of mixture plaque obtained from the extract-treated sample and untreated samples), which can imply the functionai status of MMR system of certain samples. After large T-antigen-dependent SV-40 DNA replication assay cell extract from TK6, a human lymphoblastoid B-cell lymphoma cell line with MMR ability, and Lovo, a human colonic carcinoma cell line with MMR deficiency have incubated with these heteroduplex DNA. The repair efficiency of TK6 to del(2) is more than 60%, to G-G is more than 50%. The Lovo efficiency to del(2) is less than 10%, to G-G is less than 20%.Therefore, in this in vitro model used for functional analysis of mismatch repair of heteroduplex DNA as the repair target,TK6 can serve as the control for MMR proficiency and Lovo as the control for MMR deficiency. Using this model the tumor tissue from a case of hereditary nonpolyposis colorectal cancer (microsatellite instability high, MSI-H) was measured and lack of MMR ability was shown. And a case of sporadic rectal cancer (SRC) (mierosatellite stability, MSS) maintains MMR proficiency. The results indicate that the model is sensitive and dependable. It could be used to measure the funetion status of MMR system in tumor cell and/or tissues. This is a reliable method to investigate the mechanic of tumorigenesis. It is meaningful in the observation of the role of MMR in the initiation and progression of concerned tumors.
文摘1文献来源Le D T,Kim T W,Van Cutsem E,et al.PhaseⅡopen⁃label study of pembrolizumab in treatment⁃refractory,microsatellite instability⁃high/mismatch repair⁃deficient metastatic colorectal cancer:KEYNOTE⁃164[J].J Clin Oncol,2019,38(1):11-19.2证据水平2a。3背景•微卫星高度不稳定性(microsatellite instability high,MSI⁃H)或错配修复功能缺陷(mismatch repair⁃deficient,dMMR)结直肠癌患者的预后比微卫星稳定(microsatellite stability,MSS)结直肠癌患者的预后差。
文摘免疫检查点抑制剂的出现,增加了许多实体肿瘤的治疗选择。尽管在黑素瘤和肺癌的治疗中效果良好,但大多数转移性结直肠癌患者无法从免疫治疗中获益。免疫检查点抑制剂在错配修复功能缺失转移性结直肠癌患者中明确有显著和持久的临床反应,即使在既往多线治疗失败的群体中也是如此。然而,这种临床获益仅限于小部分肿瘤患者,约占转移性结直肠癌的4%。事实上抗程序性死亡受体1(programmed cell death protein 1,PD-1)单抗对错配修复功能缺失转移性结直肠癌患者是无效的。迫切需要新颖的治疗策略使这些肿瘤具有免疫应答。破坏肿瘤的疗法(化学疗法,放射疗法和靶向疗法),从而释放肿瘤抗原,是免疫检查点抑制和其他疗法相结合的最直接的策略。这些标准疗法远没有像曾经担心的那样削弱免疫反应,反而还可以增强免疫应答。
