Mutations in epigenetic regulator KMT2C detected by liquid biopsy are associated with worse survival in prostate cancer patients

Background:KMT2(lysine methyltransferase)family enzymes are epigenetic regulators that activate gene transcription.KMT2C is mainly involved in enhancer-associated H3K4me1,and is also one of the top mutated genes in cancer(6.6%in pan-cancer).Currently,the clinical significance of KMT2C mutations in prostate cancer is understudied.Methods:We included 221 prostate cancer patients diagnosed between 2014 and 2021 in West China Hospital of Sichuan University with cell-free DNA-based liquid biopsy test results in this study.We investigated the association between KMT2C mutations,other mutations,and pathways.Furthermore,we evaluated the prognostic value of KMT2C mutations,measured by overall survival(OS)and castration resistance-free survival(CRFS).Also,we explored the prognostic value of KMT2C mutations in different patient subgroups.Lastly,we investigated the predictive value of KMT2C mutations in individuals receiving conventional combined anti-androgen blockade(CAB)and abiraterone(ABI)as measured by PSA progression-free survival(PSA-PFS).Results:The KMT2C mutation rate in this cohort is 7.24%(16/221).KMT2C-mutated patients showed worse survival than KMT2C-wild type(WT)patients regarding both CRFS and OS(CRFS:mutated:9.9 vs.WT:22.0 months,p=0.015;OS:mutated:71.9 vs.WT 137.4 months,p=0.012).KMT2C mutations were also an independent risk factor in OS[hazard ratio:3.815(1.461,9.96),p=0.006]in multivariate analyses.Additionally,we explored the association of KMT2C mutations with other genes.This showed that KMT2C mutations were associated with Serine/Threonine-Protein Kinase 11(STK11,p=0.004)and Catenin Beta 1(CTNNB1,p=0.008)mutations.In the CAB treatment,KMT2C-mutated patients had a significantly shorter PSA-PFS compared to KMT2C-WT patients.(PSA-PFS:mutated:9.9 vs.WT:17.6 months,p=0.014).Moreover,KMT2C mutations could effectively predict shorter PSA-PFS in 10 out of 23 subgroups and exhibited a strong trend in the remaining subgroups.Conclusions:KMT2C-mutated patients showed worse survival compared to KMT2C-WT patients in terms of both CRFS and OS,and KMT2C mutations were associated with STK11 and CTNNB1 mutations.Furthermore,KMT2C mutations indicated rapid progression during CAB therapy and could serve as a potential biomarker to predict therapeutic response in prostate cancer.

KMT2C通过c-Myc/CDK4信号通路调控胃癌细胞的生长与增殖

目的探究赖氨酸特异性甲基转移酶2C(lysine specific methyltransferase 2C,KMT2C)在胃癌发生发展中的作用及机制。方法通过TCGA数据库分析KMT2C在胃癌与癌旁的表达差异。采用Western blot检测KMT2C在胃癌与癌旁临床样本中的表达差异。通过Kaplan-Meier Plotter数据库分析KMT2C对胃癌患者预后的影响。采用细胞实验(克隆形成、EdU及CCK-8检测)及皮下瘤负荷模型检测KMT2C在体内外对胃癌细胞增殖能力的影响。结果KMT2C在胃癌中高表达。胃癌患者中KMT2C高表达组相对于KMT2C低表达组预后较差。敲减KMT2C在体内外均有抑制胃癌细胞增殖的作用。基因集富集分析(GSEA)发现KMT2C影响c-Myc信号通路。敲减KMT2C后,H3K4me1蛋白表达水平降低,同时,CDK4的mRNA与蛋白表达水平降低。KMT2C与c-Myc核内结合促进了c-Myc与CDK4的启动子区域的结合。结论KMT2C通过影响c-Myc/CDK4信号通路促进胃癌细胞增殖。

RNA干扰下调KMT2C基因表达对肝癌细胞HepG2增殖的影响及其机制

目的探讨组蛋白甲基化转移酶基因KMT2C对肝癌细胞HepG2的增殖影响及其可能的机制。方法采用shRNA基因干扰技术抑制HepG2细胞中KMT2C基因的表达,采用细胞计数、CCK-8细胞增殖实验以及平板克隆形成实验检测细胞增殖能力,流式细胞仪检测细胞周期变化情况;Western blotting和qRT-PCR检测KMT2C基因干扰前后HepG2细胞中EGFR的表达情况。结果甲基化转移酶KMT2C基因干扰成功后,HepG2细胞的增殖能力受到明显抑制(P<0.05),细胞周期阻滞在S期;同时细胞内的EGFR蛋白表达量显著下降(P<0.05)。结论干扰KMT2C基因的表达可以显著抑制肝癌细胞HepG2的增殖,其作用机制可能和EGFR信号通路有关。

MLL3/KMT2C突变介导肿瘤发生发展的生物学机制及其临床意义

髓样/淋巴或混合谱系白血病蛋白3(myeloid/lymphoid or mixed lineage leukemia3,MLL3),又名赖氨酸甲基转移酶2C(lysine methyltransferase 2C,KMT2C),为KMT2家族的成员之一,位于7q36.1,具有65个外显子,编码一种核蛋白,是对组蛋白3赖氨酸4(histone 3 lysine 4,H3K4)进行甲基化修饰的酶,H3K4甲基化通常与转录活性相关,二甲基和三甲基化的H3K4与基因启动子的激活有关,而单甲基化则与基因增强子^([1,2])有关。MLL家族基因被认为与组织的生长调控、肿瘤发生有关。

抑癌基因Kmt2c杂合缺失对小鼠造血系统的影响

目的:探究组蛋白甲基转移酶Kmt2c基因杂合缺失对小鼠血液系统的影响。方法:使用CRISPR/Cas9技术构建Kmt2c基因杂合缺失的模型小鼠,血常规连续监测小鼠全血细胞计数的变化;通过体外集落形成实验探究骨髓细胞的克隆性扩增能力;流式细胞术分析突变小鼠体内原始造血细胞群(长期造血干细胞、短期造血干细胞、多能祖细胞)的比例变化。结果:成功构建Kmt2c基因杂合缺失小鼠(Kmt2c^(+/-))模型,其Kmt2c mRNA表达水平是C57BL/6J小鼠的28%。Kmt2c^(+/-)小鼠骨髓细胞体外集落形成能力随着传代次数的增加而增强,并在第四代时集落数显著高于对照组(P <0.05)。Kmt2c^(+/-)小鼠原始造血细胞群中的长期造血干细胞和短期造血干细胞比例分别为19.6%±3.3%及28.9%±4.9%较对照组的16.9%±2.6%及18.9%±2.5%有增高趋势,但差异无统计学意义(P>0.05)。Kmt2c^(+/-)小鼠的白细胞计数在监测的第12周后逐渐上升在第14周时为(9.8±1.0)×10~9/L,显著高于对照组的(7.3±1.4)×10~9/L(P <0.05)。结论:Kmt2c^(+/-)小鼠的骨髓细胞具有克隆性扩增的潜能。