Biology subjects

Aaltonen, L. A.

Publications and source records attributed to Aaltonen, L. A..

9 recordsLinked to original sources

bioRxiv2026

A phosphorylation switch in PAGE4 drives MED12-mutant fibroid pathogenesis

Recurrent somatic mutations in MED12, found in [~]70% of uterine leiomyomas (ULs), define the dominant molecular subtype of these highly prevalent tumors, yet the downstream effector mechanisms remain poorly understood. Using an integrated multi-omics workflow, encompassing discovery-phase DDA proteomics of matched leiomyoma-myometrium pairs, validation-phase DIA proteomics across genetically stratified cohorts (MED12 p.G44D, RAD51B-HMGA2, IRS4/FH subtypes), phosphoproteomics, immunohistochemistry, and AP-MS interactomics, we identify prostate-associated gene 4 (PAGE4) as a central effector of MED12-mutant UL pathogenesis. PAGE4 emerged as one of the most significantly upregulated proteins in MED12-mutant ULs and harbored the highest-occupancy hyperphosphorylation sites (T51, T85) in the tumor phosphoproteome, a pattern confirmed by immunohistochemistry and orthogonal phosphoproteomics. Kinase-substrate enrichment nominated HIPK2 as the primary upstream kinase, with supporting evidence from the broader CMGC family. Subsequent analysis revealed that phosphorylation acts as a molecular switch, fundamentally restructuring the PAGE4 interactome to favor the Mediator complex and RNA Pol II transcriptional machinery. This rewiring was functionally validated by ChIP-seq and luciferase reporter assays, which demonstrated corresponding shifts in transcription factor occupancy and downstream pathway activity. Collectively, these data establish phospho-PAGE4 as a critical mechanistic node downstream of MED12 mutation, expand PAGE4 biology from prostate cancer to female reproductive tumors, and nominate it as a mechanistic biomarker and candidate therapeutic vulnerability in the most prevalent molecular subtype of uterine leiomyomas.

systems biology↗

bioRxiv2025

OMIDIENT: Multiomics Integration for Cancer by Dirichlet Auto-Encoder Networks

To achieve a more comprehensive understanding of cancer, novel computational methods are required for the integrative analysis of data from different molecular layers, such as genomics, transcriptomics, and epigenomics. Here, we present a novel multi-omics integrative method that performs unsupervised representation learning, referred to as OMIDIENT: multiOMics Integration for cancer by DIrichlet auto-ENcoder neTworks. OMIDIENT provides a natural framework for modeling sparse and compositional latent representations by employing a deep generative model, where the latent space is distributed as the product of Dirichlet distributions. Applied to five different cancers, we demonstrate that OMIDIENT outperforms the top state-of-the-art unsupervised multi-omics integrative analysis approaches in clustering, classification, and reconstruction of missing data using mRNA expression data, DNA methylation data, and microRNA expression data. Furthermore, we provide interpretability analyses for OMIDIENT that not only support its improved performance, but also offer valuable insights into the underlying structure captured by the learned representations.

bioinformatics↗

bioRxiv2023

The origin of intestinal cancer in the context of inflammation

According to conventional views, colon cancer originates from stem cells. However, inflammation, a key risk factor for colon cancer, was shown to suppress intestinal stemness. Here, we employed Paneth cells (PCs) as a model to assess the capacity of differentiated lineages to trigger tumorigenesis in the context of inflammation. Upon inflammation, PC-specific Apc mutations led to intestinal tumors reminiscent not only of those arising in inflammatory bowel disease (IBD) patients but also of a larger fraction of sporadic colon cancers. The latter is likely due to the inflammatory consequences of Western-style dietary habits, the major colon cancer risk factor. Computational methods designed to predict the cell-of-origin of cancer confirmed that, in a substantial fraction of sporadic colon cancers the cells-of-origin are secretory lineages and not stem cells. One-Sentence SummarySecretory cell lineages trigger tumor formation in the context of the major etiologic colon cancer risk factors.

cancer biology↗

bioRxiv2019

Colibactin DNA damage signature indicates causative role in colorectal cancer

Colibactin, a potent genotoxin of Escherichia coli, causes DNA double strand breaks (DSBs) in human cells. We investigated if colibactin creates a particular DNA damage signature in infected cells by identifying DSBs in colon cells after infection with pks+ E.coli. Interestingly, genomic contexts of DSBs were enriched for AT-rich penta-/hexameric sequence motifs, exhibiting a particularly narrow minor groove width and extremely negative electrostatic potential. This corresponded with the binding characteristics of colibactin to double-stranded DNA, as elucidated by docking and molecular dynamics simulations. A survey of somatic mutations at the colibactin target sites of several thousand cancer genomes revealed significant enrichment of the identified motifs in colorectal cancers. Our work provides direct evidence for a role of colibactin in the etiology of human cancer.\n\nOne sentence summaryWe identify a mutational signature of colibactin, which is significantly enriched in human colorectal cancers.

microbiology↗

bioRxiv2019

Mutational processes of distinct POLE exonuclease domain mutants drive an enrichment of a specific TP53 mutation in colorectal cancer

Cancer genomes with mutations in the exonuclease domain of Polymerase Epsilon (POLE) present with an extraordinarily high somatic mutation burden. In vitro studies have shown that distinct POLE mutants exhibit different polymerase activity and yet, how these POLE mutants generate mutations across cancer genomes and influence driver events remains poorly understood. Here we analyzed 7,345 colorectal cancer samples, including nine whole genome sequenced samples harboring POLE mutations. Our analysis identified differential mutation spectra across the mutants including methylation-independent enrichment of C>T mutations in POLE V411L. In contrast, analysis of other genomic regions showed similar mutation profiles across the different POLE mutants. Notably, we found that POLE mutants with the TP53 R213* mutation, caused by a TT[C>T]GA substitution, have significantly higher relative frequency of this mutational context compared with samples without this mutation. This finding demonstrates that variations in underlying mutation spectra can increase the likelihood of specific driver mutation formation.

genomics↗

bioRxiv2018

Retrotransposon insertions can initiate colorectal cancer and are associated with poor survival

Genomic instability pathways in colorectal cancer (CRC) have been extensively studied, but the role of retrotransposition in colorectal carcinogenesis remains poorly understood. Although retrotransposons are usually repressed, they become active in several human cancers, in particular those of the gastrointestinal tract. Here we characterize retrotransposon insertions in 202 colorectal tumor whole genomes and investigate their associations with molecular and clinical characteristics. We found highly variable retrotransposon activity among tumors and identified recurrent insertions in 15 known cancer genes. In approximately 1% of the cases we identified insertions in APC, likely to be tumor-initiating events. Insertions were positively associated with the CpG island methylator phenotype and the genomic fraction of allelic imbalance. Clinically, high number of insertions was independently associated with poor disease-specific survival.

genomics↗

bioRxiv2018

ESR1, WT1, WNT4, ATM and TERT loci are major contributors to uterine leiomyoma predisposition

Uterine leiomyomas (ULs) are benign tumors that are a major burden to womens health. A genome-wide association study on 5,417 UL cases and 331,791 controls was performed, followed by replication of the genomic risk in two cohorts. Effects of the identified risk alleles were evaluated in view of molecular and clinical features.\n\nFive loci displayed a genome-wide significant association; the previously reported TNRC6B, and four novel loci ESR1 (ER), WT1, WNT4, and ATM. The sixth hit TERT is also a conceivable target. The combined polygenic risk contributed by these loci was associated with MED12 mutation-positive tumors. The findings link genes for uterine development and genetic stability to leiomyomagenesis. While the fundamental role of sex hormones in UL aetiology has been clear, this work reveals a connection to estrogen receptor alpha on genetic level and suggests that determinants of UL growth associated with estrogen exposure have an inherited component.

genomics↗

bioRxiv2017

Germline determinants of the somatic mutation landscape in 2,642 cancer genomes

Cancers develop through somatic mutagenesis, however germline genetic variation can markedly contribute to tumorigenesis via diverse mechanisms. We discovered and phased 88 million germline single nucleotide variants, short insertions/deletions, and large structural variants in whole genomes from 2,642 cancer patients, and employed this genomic resource to study genetic determinants of somatic mutagenesis across 39 cancer types. Our analyses implicate damaging germline variants in a variety of cancer predisposition and DNA damage response genes with specific somatic mutation patterns. Mutations in the MBD4 DNA glycosylase gene showed association with elevated C>T mutagenesis at CpG dinucleotides, a ubiquitous mutational process acting across tissues. Analysis of somatic structural variation exposed complex rearrangement patterns, involving cycles of templated insertions and tandem duplications, in BRCA1-deficient tumours. Genome-wide association analysis implicated common genetic variation at the APOBEC3 gene cluster with reduced basal levels of somatic mutagenesis attributable to APOBEC cytidine deaminases across cancer types. We further inferred over a hundred polymorphic L1/LINE elements with somatic retrotransposition activity in cancer. Our study highlights the major impact of rare and common germline variants on mutational landscapes in cancer.

genomics↗

bioRxiv2017

BasePlayer: Versatile Analysis Software For Large-Scale Genomic Variant Discovery

Next-generation sequencing (NGS) is being routinely applied in life sciences and clinical practice, where the interpretation of the resulting massive data has become a critical challenge. Computational workflows, such as the Broad GATK, have been established to take raw sequencing data and produce processed data for downstream analyses. Consequently, results of these computationally demanding workflows, consisting of e.g. sequence alignment and variant calling, are increasingly being provided for customers by sequencing and bioinformatics facilities. However, downstream variant analysis, whole-genome level in particular, has been lacking a multi-purpose tool, which could take advantage of rapidly growing genomic information and integrate genetic variant, sequence, genomic annotation and regulatory (e.g. ENCODE) data interactively and in a visual fashion. Here we introduce a highly efficient and user-friendly software, BasePlayer (http://baseplayer.fi), for biological discovery in large-scale NGS data. BasePlayer enables tightly integrated comparative variant analysis and visualization of thousands of NGS data samples and millions of variants, with numerous applications in disease, regulatory and population genomics. Although BasePlayer has been designed primarily for whole-genome and exome sequencing data, it is well-suited to various study settings, diseases and organisms by supporting standard and upcoming file formats. BasePlayer transforms an ordinary desktop computer into a large-scale genomic research platform, enabling also a non-technical user to perform complex comparative variant analyses, population frequency filtering and genome level annotations under intuitive, scalable and highly-responsive user interface to facilitate everyday genetic research as well as the search of novel discoveries.

bioinformatics↗