7 P/ u) g1 f9 O病理医生常看到肿瘤的死亡细胞增多。按照新说法,这可能迫使更多的周围细胞进入增殖周期," h6 H* G( p0 \& V# M
G0期细胞的比例减少,从而导致肿瘤组织的结构紊乱,病理学上称之为分化差。 + ^5 v* w4 d" B2 j$ ^+ I # l6 f" {3 `$ I( O7 L/ k. B ! _9 k3 u$ H1 _) u3 U. D
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) Q* a* D: R* Y( }/ y- V, \- n多年以来,病理医生常用细胞的有丝分裂像作为判断肿瘤增殖速度、恶性度的指标。但在实际应用中 ; ?; [- F. L# _, `这一指标的使用受到很大的限制。2 S9 H1 K+ O& x a( u
免疫组织化学解决了这一问题。5 e" @: {) E3 K. N3 M
Ki67单克隆抗体是在位于德国Kiel 8 v- h. N( O. x& M市的一所大学建立而得名。& C# S/ C- L; N
Ki67免疫组化染色可将大部分 - t S p; I% P$ W* R4 ^G0期以外的细胞标记,因而也被称为细胞的增殖指 & n! d4 j+ C- T8 r数。 ( l# p% E x& d1 V' o0 x3 R/ H8 MKi67的阳性率越高,说明处于增殖周期的细胞比例越高,肿瘤生长越快;而8 X: o4 s& H, _) G
G0期细胞自然就越少,组织分化越差。 . g: q% b A2 x 5 g' w/ k2 q5 j6 v. |+ |; F# S
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" K A, f0 q6 L. z+ T有意思的是,+ p" A o- _! Y
Ki67的阳性比例常与细胞死亡的频度成正比。那么是细胞增殖多导致了死亡多,还是细 0 s. K% }+ u, |! J胞死亡多导致了增殖多呢?如果是前者,应该是细胞死亡越多,则患者预后越好。但事实是,细胞死亡越0 V ~2 ]4 [& |7 a* b; \
多,患者的生存期常越短。所以,死亡增多导致增殖增加的推测更为合理。& F4 @" a! K+ [+ n& P
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First- and second-generation EGFR TKIs are established first line therapy for patients with NSCLC with activating mutations in EGFR. Unfortunately, patients ultimately develop disease progression with acquisition of a second-site EGFR T790M mutation in more than half of cases. This has led to the development of third generation EGFR TKIs which inhibit both the EGFRm+ and T790M mutations in preclinical models and are showing activity in TKI-resistant patients in Phase I studies. Despite the potential improvements brought by third generation EGFR-TKIs, advanced EGFRm+ tumor cells will still remain highly adaptable and the inevitability of further resistance will limit the effectiveness of these drugs. As such, the identification of resistance mechanisms to these agents is essential to guide future therapeutic strategies and identify novel:novel combinations.+ g. k+ Y! d! u W8 O; _0 }* [: x
To interrogate resistance to AZD9291, we have generated panels of EGFRm+ cell lines resistant to gefitinib (first generation TKI) and EGFRm+ and EGFRm+/T790M cell lines resistant to afatinib and AZD9291 (second and third generation TKIs, respectively). Subsequently, we characterised the cell lines using a variety of molecular profiling techniques including Next Generation Sequencing (NGS), Affymetrix gene expression analysis, and phenotypic profiling following pharmacological modulation by small molecule inhibitors of canonical signaling pathways. Y9 F% o5 r2 T/ O The effects on cell survival across the range of resistant models by a panel of pathway inhibitors indicated that resistance to the EGFR inhibitors, in particular AZD9291, is frequently associated with increased sensitivity to selumetinib (AZD6244; ARRY-142886) (MEK1/2 inhibitor), suggesting that ERK signaling is commonly reactivated to circumvent inhibition of the EGFR pathway. Molecular characterisation of the panel of cell lines suggests a range of different resistance mechanisms may be responsible for reactivation of ERK signaling, including a decrease in negative regulators of ERK such as DUSP6 or an epithelial to mesenchymal transition consistent with previous observations. + }8 G, [3 n |1 w Collectively, these data suggest that combining an EGFR TKI with a MEK inhibitor could prevent or delay resistance and drive superior duration of benefit from these agents. + }, }: L0 \( ~1 S4 T1 S5 g f x$ i2 S $ k* u. J6 A- s P Y总结:“总的来说,这些数据表明,联合EGFR和MEK抑制剂可以防止或推迟AZD9291的耐药,使患者从药物的获益时间增长。”" M6 i: r* z5 ^+ t& ^; Y
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