Differentiation and Elimination of Chemo-surviving Colon Tumors

描述(由申请人提供)： 尽管使用了积极的手术切除和化疗，但近50%的结直肠癌患者会复发，这突显了改进治疗的必要性。结直肠癌是美国第三大致死性癌症。结直肠癌患者未能产生长期临床缓解可能反映了无法有效地靶向癌症干细胞或干细胞样细胞(CSCs/CSLC；表达癌症干细胞标记物)，因为已知这些细胞对传统疗法具有耐药性。分化治疗导致CSLCs丧失自我更新，诱导终末分化或凋亡，可能是治疗复发性结直肠癌的有效选择。我们已经证明，miR-21是一种新的癌基因，它通过激活结肠癌细胞中的Wnt/β-catenin和EGFR信号来诱导干性，刺激肿瘤的促进、侵袭和转移。在5-FU+奥沙利铂(FUOX)耐药的结肠癌细胞中，miR-21的表达也显著升高；miR-21的下调导致这些细胞的分化，CK-20的表达和碱性磷酸酶活性的增加就是明证。此外，这种下调使得耐FUOX的结肠癌细胞不仅对FUOX敏感，而且对3，4-二氟苯并姜黄素(CDF)或二氟化姜黄素(CDF)以及CDF和FUOX的组合也敏感。CDF是一种新型的饮食成分姜黄素的类似物，比母体化合物具有更大的生物利用度和生长抑制特性。此外，我们还观察到，在CDF或CDF和FUOX的联合作用下，miR-21下调的FUOX耐药结肠癌细胞的EGFR和CD44表达减少，细胞凋亡率增加。CDF单用及CDF与FUOX联用的疗效明显优于单用FUOX。我们建议在临床前环境中推广这种分化疗法。因此，我们将使用SCID小鼠异种移植和结肠癌原位模型来验证这样的假设：在化疗中，在存活的结肠癌患者中，antagomir-21(反义miR-21)下调miR-21将导致已知富含CSCs/CSLCs的化疗耐药肿瘤细胞的分化。我们进一步假设，虽然后续的FUOX治疗在消除难治性结肠肿瘤方面只有部分有效，但CDF或CDF和FUOX的联合治疗将通过抑制Wnt/β-catenin和EGFR信号通路杀死分化的耐药结肠CSCs/CSLC，从而在导致肿瘤完全或接近完全消退方面非常有效。最后，我们将证明miR-21在结肠癌化疗耐药细胞中调节？-Wnt/catenin和EGFR信号通路。

DESCRIPTION (provided by applicant): Despite the use of aggressive surgical resection and chemotherapy, nearly 50% of patients with colorectal carcinoma, the 3rd deadliest cancer in the US, will develop recurrent disease, highlighting the need for improved therapies. The failure to produce long-term clinical remission in CRC patients could reflect the inability to target cancer stem or stem-like cells (CSCs/CSLCs; that express cancer stem cell markers) efficiently since these cells are known to be resistant to conventional therapies. Differentiation therapy, which results in loss of self-renewal and induction of terminal differentiation or apoptosis in CSLCs, may be a valid option for the treatment of recurrent colorectal cancer. We have shown that miR-21, an emerging oncogene which induces stemness by activating Wnt/¿-catenin and EGFR signaling in colon cancer cells stimulates tumor promotion, invasion and metastasis. miR-21 is also greatly elevated in 5-FU + Oxaliplatin (FUOX) resistant colon cancer cells; downregulation of miR-21 leads to differentiation of these cells, as evidenced by increased CK-20 expression and alkaline phosphatase activity. Moreover, this downregulation renders the FUOX-resistant colon cancer cells susceptible not only to FUOX but also to 3, 4-difluorobenzo-curcumin or difluorinated curcumin (CDF) and the combination of CDF and FUOX. CDF is a novel analog of the dietary ingredient curcumin with much greater bioavailability and growth inhibitory properties than the parent compound. Additionally, we have observed that in response to CDF or the combination CDF and FUOX, miR-21-downregulated FUOX-resistant colon cancer cells exhibit decreased expression of EGFR and CD44 and increased apoptosis. CDF alone and the combination of CDF and FUOX were much more effective than FUOX alone. We propose to extend this differentiation therapy in a preclinical setting. Therefore, we will use SCID mice xenograft and orthotopic models of colon cancer to test the hypothesis that down regulation of miR-21 by antagomir-21 (antisense miR-21) in chemotherapy surviving colon tumors will lead to differentiation of chemotherapy-resistant tumor cells known to be enriched in CSCs/CSLCs. We further hypothesize that while subsequent treatment with FUOX will only be partially effective in obliterating the refractory colon tumors, treatment with either CDF or the combination of CDF and FUOX will be highly effective in causing a complete or near complete regression of the tumor by killing differentiating chemo-resistant colon CSCs/CSLCs through inhibition of Wnt/¿-catenin and EGFR signaling. Finally, we will demonstrate that miR-21 regulates ¿-Wnt/catenin and EGFR signaling pathways in colon cancer chemo-resistant cells in vitro.