Biology subjects

Tay, Y.

Publications and source records attributed to Tay, Y..

4 recordsLinked to original sources

bioRxiv2023

An isoform-resolution transcriptomic atlas of colorectal cancer from long-read single-cell sequencing

Colorectal cancer (CRC) is the second leading cause of cancer death worldwide. In recent years, short-read single-cell RNA sequencing (scRNA-seq) has been instrumental in deciphering tumor cell heterogeneities. However, these studies only enable gene-level expression quantification but neglect alterations in transcript structures, which arise from alternative end processing or splicing, and are frequently observed in cancer. In this study, we integrated short- and long-read scRNA-seq of CRC patient samples to build the first isoform-resolution CRC transcriptomic atlas. We identified 394 dysregulated transcript structures in tumor epithelial cells, including 299 resulting from various combinations of multiple splicing events. Secondly, we characterized genes and isoforms associated with epithelial lineages and subpopulations that exhibit distinct prognoses. Finally, we built an algorithm that integrated novel peptides derived from predicted ORFs of recurrent tumor-specific transcripts with mass spectrometry data and identified a panel of recurring neoepitopes that may aid the development of neoantigen-based cancer vaccines.

cancer biology↗

bioRxiv2020

Pseudogene-mediated DNA demethylation leads to oncogene activation

Despite being one of the leading causes of cancer-related deaths, there is an unmet clinical need for hepatocellular carcinoma (HCC) patients. The lack of effective treatment is, at least in part, due to our lack of understanding of the molecular pathogenesis of this disease. Oncofetal protein SALL4 is re-activated in patients with aggressive HCC along with other solid tumors and hematologic malignancies. This study identifies a previously unrecognized mechanism of SALL4 reactivation which is mediated by pseudogene-induced demethylation. Using a locus-specific demethylating technology, we identified the critical CpG region for SALL4 expression. We showed that SALL4 pseudogene 5 hypomethylates this region through interaction with DNMT1, resulting in SALL4 upregulation. Intriguingly, pseudogene 5 is significantly upregulated in a hepatitis B virus (HBV) model prior to SALL4 induction, and both are increased in HBV-HCC patients. Our results suggest that pseudogene-mediated demethylation represents a unique mechanism of oncogene activation in cancer. SignificanceOur study provides a mechanistic link between HBV infection, activation of the oncogene SALL4, and HCC. We reveal a previously undescribed capability of a pseudogene to epigenetically activate an oncogene by demethylation in a locus-specific manner.

cancer biology↗

bioRxiv2020

TIP60 acetylates H2AZ and regulates doxorubicin-induced DNA damage sensitivity through RAD51 transcription

TIP60, a lysine acetyltransferase and H2AZ, a histone H2A variant are involved in transcription and DNA repair. Recent studies suggest that H2AZ acetylation is dependent on TIP60. Here, we show that TIP60 acetylates both isoforms of H2AZ in vitro and in cells. Utilizing ChIP-seq and RNA-seq to identify the genes regulated by TIP60-dependent acetylation of H2AZ, we find that TIP60-dependent acetylation of H2AZ correlates with the expression of genes involved in DNA damage repair, amongst several other pathways. In line with this, TIP60-depleted cells exhibit increased sensitivity to the DNA damage-inducing drug doxorubicin. Restoring the expression level of RAD51, one of the genes involved in the DNA damage repair pathway, partially rescues the doxorubicin sensitivity due to TIP60 depletion. Overall, our study uncovers a role for TIP60 in regulating doxorubicin-induced DNA damage sensitivity in a manner dependent on RAD51 transcription.

molecular biology↗

bioRxiv2018

Pan-cancer analysis of RNA binding proteins (RBPs) reveals the involvement of the core pre-mRNA splicing and translation machinery in tumorigenesis

RNA binding proteins (RBPs) are key regulators of posttranscriptional processes such as RNA maturation, transport, localization, turnover and translation. Despite their dysregulation in various diseases including cancer, the landscape of RBP expression and regulatory mechanisms in human cancer has not been well characterized. Here, we analyzed mRNA expression of 1487 RBPs in ~6700 clinical samples across 16 human cancer types and found that there were significantly more upregulated RBPs than downregulated ones in tumors when compared to their adjacent normal tissues. Across almost all of the 16 cancer types, 109 RBPs were consistently upregulated (cuRBPs) while only 41 RBPs were consistently downregulated (cdRBPs). Integrating expression with the copy number and DNA methylation data, we found that the overexpression of cuRBPs is largely associated with the amplification of copy number, whereas the downregulation of cdRBPs may be a result of epigenetic silencing mediated by DNA methylation. Furthermore, our results indicated that cuRBPs could work together to promote cancer progression potentially through the involvement of splicing and translation machinery, while cdRBPs might function independently to suppress tumorigenesis. Additionally, we focused on colon cancer and identified several novel potential oncogenic RBPs, such as PABPC1L which might promote cancer development via regulating the core splicing machinery. In summary, we showed distinct expression landscapes, regulatory mechanisms and characteristics of cuRBPs and cdRBPs and implicated several novel RBPs in cancer pathogenesis. Moreover, our results suggest that the involvement of the core pre-mRNA splicing and translation machinery could be critical in tumorigenesis.

systems biology↗