p38gamma MAPK signaling promotes intestinal tumorigenesis

结直肠癌（CRC）是美国恶性相关死亡的第二大原因， 炎症是其发展、生长和进展的关键驱动力。p38 p38的成员 丝裂原活化蛋白激酶（p38 MAPK激酶和p38 MAPK激酶），是致癌的，促炎的， 在临床CRC中过度表达，但上皮p38 β在CRC肿瘤发生中的作用尚未得到证实。- 连环蛋白是Wnt转录的关键辅因子，在90%的CRC中被异常激活。然而，β-连环蛋白是 因此迫切需要鉴定可药用的β-连环蛋白激活剂用于治疗 干预在这里，我们提出肠上皮细胞（IEC）中的p38 MAPK驱动CRC 通过刺激致癌的β-连环蛋白磷酸化来促进肿瘤发生。 这一假设是基于我们的初步研究表明：1）炎症协调刺激 p38 β和β-连环蛋白在CRC细胞中的磷酸化; 2）p38 β在S605处直接磷酸化β-连环蛋白， 增加β-连环蛋白稳定性、β-连环蛋白-TCF 4相互作用、Wnt转录和CRC生长; 3） 炎症激活小鼠肠组织中的p38 β，但不激活p38 β，IEC特异性p38 β敲除（KO） 降低促炎细胞因子表达并减轻结肠炎严重程度; 4）IEC p38 K50抑制结肠炎 氧化偶氮甲烷（AOM）/葡聚糖硫酸钠（DSS）中的肿瘤发生和β-catenin/S605/Wnt信号转导 结肠炎相关癌症（CAC）小鼠模型; 5）p38 β药理学抑制剂吡非尼酮（PFD） 在野生型（WT）小鼠中抑制β-连环蛋白/细胞因子表达和结肠肿瘤发生，但在p38 β KO中不抑制 小鼠，并进一步与β-连环蛋白-TCF 4相互作用拮抗剂LF 3和化疗药物合作 5 FU抑制CRC生长，以及6）p38 β在临床CAC样本和大肠癌患者的肠组织中上调。 Apcmin和白细胞介素-10敲除（IL-10-/-）小鼠。这些结果共同表明，IEC p38要求 通过刺激致癌β-连环蛋白磷酸化导致CAC和散发性CRC的肿瘤发生。 使用遗传学和药理学方法，我们将通过确定（1）如果p38突变， 诱导的β-catenin/S605磷酸化刺激β-catenin核转位，β-catenin-TCF 4 相互作用、Wnt转录和CRC生长;（2）如果IEC特异性p38 PKO阻断IL-10中的肿瘤发生， 10-/-和Apcmin小鼠，并且如果p38 β对于β-连环蛋白/TCF 4/Wnt信号传导是必需的，则促进恶性肿瘤的发生。 CRC发病机制的进展;和（3）如果p38 β药理学抑制剂吡非尼酮（PFD） 阻断CRC肿瘤发生，并通过破坏 p38 β/β-catenin/TCF 4/Wnt通路。完成后，这些研究将证明上皮p38是否能抑制 通过刺激致癌β-连环蛋白/S605磷酸化和Wnt转录促进CRC肿瘤发生。 证明PFD通过靶向抑制Wnt信号传导和CRC肿瘤发生的有效性 肠上皮p38基因的表达将揭示p38基因药物化在结肠癌靶向治疗中具有巨大的潜力。

Colorectal cancer (CRC) is the second leading cause of malignant-associated death in the USA with inflammation as a key driving force for its development, growth, and progression. p38, a member of p38 mitogen-activated protein kinases (p38 MAPK  , and ), is oncogenic, pro-inflammatory, and overexpressed in clinical CRC but the role of epithelial p38 in CRC tumorigenesis has not been tested. - catenin, a critical cofactor of Wnt transcription, is aberrantly activated in 90% of CRC. And yet, -catenin is undruggable and there is thus an urgent need to identify druggable -catenin activators for therapeutic intervention. Here we propose that p38 MAPK in intestinal epithelial cells (IEC) drives CRC tumorigenesis by stimulating oncogenic -catenin phosphorylation. This hypothesis is based on our preliminary studies showing that: 1) inflammation coordinately stimulates p38 and -catenin phosphorylation in CRC cells; 2) p38 directly phosphorylates -catenin at S605, which increases -catenin stability, the -catenin-TCF4 interaction, Wnt transcription and CRC growth; 3) inflammation activates p38, but not p38, in intestinal tissues of mice, and IEC-specific p38 knockout (KO) reduces pro-inflammatory cytokine expression and attenuates colitis severity; 4) IEC p38 KO inhibits colon tumorigenesis and p--catenin/S605/Wnt signaling in the azoxymethane (AOM)/dextran sodium sulfate (DSS) mouse model of colitis-associated cancer (CAC); 5) the p38 pharmacological inhibitor pirfenidone (PFD) suppresses -catenin/cytokine expression and colon tumorigenesis in wild-type (WT) mice, but not in p38 KO mice, and further collaborates with the -catenin-TCF4 interaction antagonist LF3 and chemotherapeutic drug 5FU to inhibit CRC growth, and 6) p38 is upregulated in clinical CAC specimens and in intestinal tissues of Apcmin and interleukin-10 knockout (IL-10-/-) mice. These results together indicate that IEC p38 is required for tumorigenesis of both CAC and sporadic CRC by stimulating oncogenic -catenin phosphorylation. Using genetic and pharmacological approaches, we will test this hypothesis by determining (1) if p38- induced -catenin/S605 phosphorylation stimulates -catenin nuclear translocation, -catenin-TCF4 interaction, Wnt transcription and CRC growth; (2) if IEC-specific p38 KO blocks tumorigenesis in IL- 10-/- and Apcmin mice and if p38 is essential for the -catenin/TCF4/Wnt signaling to promote malignant progression in CRC pathogenesis; and (3) if the p38 pharmacological inhibitor pirfenidone (PFD) blocks CRC tumorigenesis and increases the growth-inhibitory activity of LF3 and 5FU by disrupting the p38/-catenin/TCF4/Wnt pathway. Upon completion, these studies will demonstrate if epithelial p38 promotes CRC tumorigenesis by stimulating oncogenic -catenin/S605 phosphorylation and Wnt transcription. Demonstrating the effectiveness of PFD in inhibiting Wnt signaling and CRC tumorigenesis by targeting intestinal epithelial p38 will reveal that drugging p38 has a great potential for colon cancer targeted therapy.