Inhibition of IGF-1R: A Therapeutic Strategy for Colon Cancer Stem-like Cells

抑制 IGF-1R：结肠癌干细胞样细胞的治疗策略

• 批准号: 8600841
• 负责人: Bhaumik B Patel
• 金额: --
• 依托单位: VA VETERANS ADMINISTRATION HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-04-01 至 2015-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8600841
• 关键词: ABCG2 gene; Age-Years; Aging; Cancer Diagnostics; Cells; Clinic; Colon; Colon Carcinoma; Colorectal; Colorectal Cancer; Disease; Dose; Effectiveness; Embryo; Fluorouracil; Gene Expression; Gene Targeting; Genes; Goals; Growth; Health; Human; In Vitro; Incidence; Insulin-Like Growth Factor II; Integrin alphaV; Investigation; Lead; Ligands; Malignant Neoplasms; Measures; MicroRNAs; Myeloid Cells; Neoplasm Metastasis; Outcome; Pathway interactions; Phenotype; Play; Population; Process; Recurrent disease; Regulator Genes; Resistance; Role; Stem cells; Testing; Therapeutic; Thymidylate Synthase; Time; Treatment outcome; Tyrosine Kinase Inhibitor; Vertebral column; Veterans; Xenograft procedure; base; cancer cell; cancer stem cell; cell growth; cell type; chemotherapy; improved; in vivo; killings; leukemia; mortality; overexpression; oxaliplatin; patient population; preclinical study; research study; self-renewal; stem; tumor

Despite recent advances in therapeutics, colorectal cancer remains the third deadliest cancer in the USA. This is mainly attributable to survival of a small population of cancer cells called stem cells (CSCs) with the ability to self-renew, resist chemotherapy killing and metastasize (broadly speaking CSC phenotype). We have generated cells resistant to a combination of 5-flurouracil (5-FU) and oxaliplatin (FUOX), the backbone of colorectal cancer chemotherapeutics. These FUOX-resistant cells are enriched in CSCs and show increased expression of total and activated form of IGF-1R as well as its ligand IGF-2. Inhibition of IGF-1R by a tyrosine kinase inhibitor, GSK1904529A, results in a dose dependant decrease in colonosphere formation (a measure of CSCs growth) which is especially pronounced in p53 wild type cells. Moreover, combination of FUOX with GSK1904529A results in not only synergistic inhibition of primary colonosphere formation but also secondary sphere formation suggesting IGF-1R may play a role in CSCs self-renewal. MicroRNAs (miRs) have been identified as important negative regulators of gene expression in embryonic and cancer stem cell growth. We hypothesized that IGF-1R inhibition would lead to a change in expression of specific miRs. Indeed, we identified miR-363, a non p53 regulated miR, and miR-215, a p53 regulated miR, to be highly overexpressed (28-fold and 6-fold respectively) following IGF-1R inhibition. More importantly, we found that expression of miR-363 and -215 is decreased several fold in FUOX-resistant cells that are enriched in CSCs. At the same time, expression of thymidylate synthase (TS), the putative target of miR-215, as well as integrin alpha-V (CD51) and myeloid cell leukemia-1 (MCL-1), both targets of miR-363 and regulator of CSC phenotype, were highly overexpressed in FUOX-resistant cells. Moreover, both miRs and their respective targets can be favorably modulated by IGF-1R inhibition. Based on the above observation we hypothesize, that IGF-1R inhibition alters the cancer stem cell phenotype thus enhancing effectiveness of chemotherapy in FUOX-resistant colorectal cells. We further hypothesize that this enhanced efficacy is due, in part, to induction of p53 dependent (miR-215) and independent (miR-363) microRNAs. To test this hypothesis, we will examine the effect of IGF-1R inhibition in primary human colon cancer cells (propagated as colonospheres) on CSC phenotype in vitro and the role of miR-215 and miR-363 in the process (Aim 1). We will also test the effect of IGF-1R depletion/inhibition on tumor formation and xenograft growth (with and without FUOX) in vivo (Aim 2). Lastly, we will delineate the role of specific miR-215 (TS and ABCG2) as well as miR-363 (CD51 and MCL-1) target genes in modulating CSC phenotype (Aim 3). The results from the proposed experiments would expand our understanding of mechanisms of colon CSCs growth and chemotherapy resistance resulting in a paradigm shift in treatment of colorectal cancer improving outcome for this deadly disease.

尽管最近在治疗方面取得了进展，但结直肠癌仍然是美国第三大致命癌症。这主要是由于一小部分被称为干细胞（CSC）的癌细胞的存活，它们具有自我更新、抵抗化疗杀伤和转移的能力（广义上讲CSC表型）。我们已经产生了对5-氟尿嘧啶（5-FU）和奥沙利铂（FUOX）联合耐药的细胞，这是结直肠癌化疗药物的支柱。这些富氧耐药细胞在CSCs中富集，并表现出IGF-1R及其配体IGF-2的总和活化形式的表达增加。酪氨酸激酶抑制剂GSK1904529A对IGF-1R的抑制导致结肠圈形成（CSCs生长的一个指标）的剂量依赖性减少，这在p53野生型细胞中尤其明显。此外，FUOX与GSK1904529A联合使用不仅可以协同抑制初级结肠圈的形成，还可以抑制次级结肠圈的形成，这表明IGF-1R可能在CSCs的自我更新中发挥作用。MicroRNAs （miRs）已被确定为重要的阴性