González-Espinoza Alfredo, Zamora-Fuentes Jose, Hernández-Lemus Enrique, Espinal-Enríquez Jesús
Department of Biology, University of Pennsylvania, Philadelphia, PA, United States.
Computational Genomics Division, National Institute of Genomic Medicine, Mexico City, Mexico.
Front Oncol. 2021 Nov 17;11:726493. doi: 10.3389/fonc.2021.726493. eCollection 2021.
Gene regulatory and signaling phenomena are known to be relevant players underlying the establishment of cellular phenotypes. It is also known that such regulatory programs are disrupted in cancer, leading to the onset and development of malignant phenotypes. Gene co-expression matrices have allowed us to compare and analyze complex phenotypes such as breast cancer (BrCa) and their control counterparts. Global co-expression patterns have revealed, for instance, that the highest gene-gene co-expression interactions often occur between genes from the same chromosome (), meanwhile inter-chromosome () interactions are scarce and have lower correlation values. Furthermore, strength of correlations have been shown to decay with the chromosome distance of gene couples. Despite this has been clearly identified, it has been observed only in a small fraction of the whole co-expression landscape, namely the most significant interactions. For that reason, an approach that takes into account the whole interaction set results appealing. In this work, we developed a hybrid method to analyze whole-chromosome Pearson correlation matrices for the four BrCa subtypes (Luminal A, Luminal B, HER2+ and Basal), as well as adjacent normal breast tissue derived matrices. We implemented a systematic method for clustering gene couples, by using eigenvalue spectral decomposition and the -medoids algorithm, allowing us to determine a number of clusters without removing any interaction. With this method we compared, for each chromosome in the five phenotypes: Whether or not the gene-gene co-expression decays with the distance in the breast cancer subtypes the chromosome location of clusters of gene couples, and whether or not the is observed in the whole range of interactions. We found that in the correlation matrix for the control phenotype, positive and negative Pearson correlations deviate from a random null model independently of the distance between couples. Conversely, for all BrCa subtypes, in all chromosomes, positive correlations decay with distance, and negative correlations do not differ from the null model. We also found that BrCa clusters are distance-dependent, meanwhile for the control phenotype, chromosome location does not determine the clustering. To our knowledge, this is the first time that a dependence on distance is reported for gene clusters in breast cancer. Since this method uses the whole interaction geneset, combination with other -omics approaches may provide further evidence to understand in a more integrative fashion, the mechanisms that disrupt gene regulation in cancer.
基因调控和信号转导现象是细胞表型建立的重要相关因素。众所周知,此类调控程序在癌症中会被破坏,从而导致恶性表型的发生和发展。基因共表达矩阵使我们能够比较和分析诸如乳腺癌(BrCa)及其对照样本等复杂表型。例如,全局共表达模式显示,最高的基因 - 基因共表达相互作用通常发生在来自同一条染色体的基因之间(),而染色体间()相互作用较少且相关性值较低。此外,相关性强度已被证明会随着基因对的染色体距离而衰减。尽管这一点已被明确识别,但仅在整个共表达图谱的一小部分,即最显著的相互作用中被观察到。因此,一种考虑整个相互作用集的方法很有吸引力。在这项工作中,我们开发了一种混合方法来分析四种BrCa亚型(Luminal A、Luminal B、HER2 + 和基底型)以及相邻正常乳腺组织衍生矩阵的全染色体皮尔逊相关矩阵。我们通过使用特征值谱分解和 - 中位数算法实现了一种系统的基因对聚类方法,使我们能够确定聚类数量而不删除任何相互作用。使用这种方法,我们针对五种表型中的每条染色体比较了:基因 - 基因共表达在乳腺癌亚型中是否随距离衰减;基因对聚类的染色体位置;以及在整个相互作用范围内是否观察到。我们发现,在对照表型的相关矩阵中,正、负皮尔逊相关性独立于基因对之间的距离偏离随机零模型。相反,对于所有BrCa亚型,在所有染色体中,正相关性随距离衰减,而负相关性与零模型无差异。我们还发现BrCa聚类是距离依赖性的,而对于对照表型,染色体位置并不决定聚类。据我们所知,这是首次报道乳腺癌中基因聚类存在距离依赖性。由于该方法使用了整个相互作用基因集,与其他 - 组学方法相结合可能会提供进一步的证据,以便以更综合的方式理解破坏癌症中基因调控的机制。