Biology subjects

Morgan, J. S.

Publications and source records attributed to Morgan, J. S..

4 recordsLinked to original sources

bioRxiv2026

Insulin receptor substrate 2 (IRS2) confers resistance to PI3K pathway inhibition in PIK3CA mutant breast cancer

Activating mutations in PI3K are one of the most frequent mutations in breast cancer and are associated with worse patient outcomes in many breast cancer subtypes. Despite intense interest, cancer treatments that target the PI3K pathway have been only modestly effective due to intrinsic and acquired resistance mechanisms which reactivate PI3K signaling. Here, we characterize a feedback mechanism by which PI3K pathway inhibitors increase insulin receptor substrate 2 (IRS2) abundance and demonstrate the role of IRS2 in promoting resistance to these drugs. In PIK3CA mutant breast tumors and cell lines, there is a significant reduction in IRS2 mRNA and protein abundance which is reversed by PI3K pathway inhibition and mediated by the transcription factor FOXO3. PIK3CA mutations do not alter IRS1 expression. IRS2 confers resistance to PI3K pathway inhibition by sustaining PI3K signaling in PIK3CA mutant, but not wild-type breast cancer cells. Increased IRS2 abundance also correlates with PI3K pathway inhibitor resistance across PI3K mutant cancer cell lines from a variety of tissues. The clinical relevance of these findings is highlighted by the frequency of PI3K mutations in cancer and the identification of a new target to address the challenges associated with prior efforts to block the reactivation of PI3K signaling during PI3K inhibition.

cancer biology↗

bioRxiv2025

Therapeutic delivery of albumin-binding siRNA targeting IRS2 to diverse cell types reduces mammary tumor growth

Oligonucleotide therapeutics are a new class of drugs that enable robust and sustained modulation of gene expression. However, achieving efficient delivery of siRNAs to tumors is a challenge for therapy. Here, we demonstrate that fully chemically modified siRNAs conjugated with an albumin-binding dendrimer are efficiently delivered to both neoplastic and stromal/immune cells within primary TNBC mammary tumors. siRNAs were designed to selectively target IRS2, a signaling adaptor of insulin and insulin-like growth factor signaling that has been implicated in aggressive breast cancers. These siRNAs reduced Irs2 expression in tumor and stromal cells without causing hyperglycemia, resulting in reduced tumor growth that was associated with decreased vascularization and alterations in macrophage polarization and the expression of EMT proteins. This work demonstrates that siRNAs can be delivered to neoplastic and specific stromal populations in mammary tumors and that they can effectively and specifically silence a driver of aggressive breast cancer.

cancer biology↗

bioRxiv2025

Interaction of IRS2 with PLK1 protects cells from mitotic stress

In this study we identify a role for IRS2 in the protection of cells from mitotic stress through its interaction with PLK1. IRS2 is an adaptor protein for the insulin and IGF-1 receptors that mediates their signaling functions. In this capacity, IRS2 is tyrosine phosphorylated to recruit signaling effectors that control cellular outcomes. A role for IRS2 in mitotic regulation has been reported, but the mechanism of IRS2 action in this regulation has not been determined. Here we report that IRS2 interacts with PLK1 in a CDK1-dependent manner, and they co-localize at centrosomes in mitotic cells. In response to mitotic stress, cells that lack IRS2 or express a PLK1-binding deficient mutant exhibit reduced centrosome separation and a shortened mitotic arrest that leads to reduced tumor cell viability. In contrast, cells expressing an IRS2 mutant that is not tyrosine phosphorylated display normal mitotic function. Together, our findings establish a mechanistic connection between IRS2 and mitotic regulation that is distinct from its function as a signaling adaptor protein.

cell biology↗

bioRxiv2023

Fluorescent tagging of endogenous IRS2 with an auxin-dependent degron to assess dynamic intracellular localization and function

Insulin Receptor Substrate 2 (IRS2) is a signaling adaptor protein for the insulin (IR) and Insulin-like Growth Factor-1 (IGF-1R) receptors. In breast cancer, IRS2 contributes to both initiation of primary tumor growth and establishment of secondary metastases through regulation of cancer stem cell (CSC) function and invasion. However, how IRS2 mediates its diverse functions is not well understood. We used CRISPR/Cas9-mediated gene editing to modify endogenous IRS2 to study the expression, localization, and function of this adaptor protein. A cassette containing an auxin inducible degradation (AID) sequence, 3X-FLAG tag and mNeon-green was introduced at the N-terminus of the IRS2 gene to provide rapid and reversible control of IRS2 protein degradation and analysis of endogenous IRS2 expression and localization. Live fluorescence imaging of these cells revealed that IRS2 shuttles between the cytoplasm and nucleus in response to growth regulatory signals, and deletion of a putative nuclear export sequence in the C-terminal tail promotes nuclear retention of IRS2. Moreover, acute induction of IRS2 degradation reduces CSC function, similar to the constitutive knockout of IRS2. Our data highlight the value of our model of endogenously tagged IRS2 as a tool to elucidate IRS2 localization and function.

cell biology↗