Study Identifies SHIP2 Protein as Key Driver of Chemotherapy Resistance in Breast Cancer
Researchers have identified the protein SHIP2 (encoded by INPPL1) as a critical regulator of resistance to fluoropyrimidine-based chemotherapies such as 5-FU and floxuridine in breast cancer cells. SHIP2 promotes resistance by elevating levels of the enzyme thymidylate synthase (TYMS) through a signaling chain involving SRC and β-catenin, bypassing a normal tumor-suppressor-dependent control mechanism. The findings suggest that targeting SHIP2, SRC, or β-catenin could restore chemotherapy sensitivity in patients whose tumors express high levels of INPPL1.
Fluoropyrimidine chemotherapies, including 5-fluorouracil (5-FU) and floxuridine (FuDR), are among the most commonly used cancer treatments, but their effectiveness is frequently undermined by tumors that develop adaptive resistance. A new preprint study posted to bioRxiv identifies SHIP2, the protein product of the INPPL1 gene, as a previously unrecognized regulator of this resistance in breast cancer cells. The researchers found that SHIP2 drives elevated expression of thymidylate synthase (TYMS)—the primary molecular target of fluoropyrimidines—at the transcriptional level, and does so independently of its known phosphatase enzymatic activity. Mechanistically, SHIP2 increases SRC kinase levels and promotes nuclear accumulation of β-catenin, which together sustain TYMS expression even under chemotherapeutic stress. Crucially, SHIP2 appears to rewire TYMS regulation away from a P53-dependent pathway toward this β-catenin-driven program, allowing cancer cells to maintain high TYMS levels even when P53 function is engaged. Inhibiting either SRC or β-catenin was shown to suppress TYMS induction and partially restore drug sensitivity in cell models. Analysis of patient cancer datasets further supported the model, with high INPPL1 expression correlating with elevated TYMS levels and worse clinical outcomes, pointing to SHIP2 as a potential therapeutic target.
What's missing
As a preprint, this study has not yet undergone peer review, and all findings should be considered preliminary. The mechanistic work was conducted primarily in breast cancer cell lines, and it is unclear how well results will translate to in vivo models or other cancer types where fluoropyrimidines are used. The study does not report data from clinical trials or direct patient-level intervention, so the therapeutic utility of targeting SHIP2 remains undemonstrated. The correlation between INPPL1 expression and outcomes in patient datasets is associative and does not establish causality.
What different sources said
- bioRxivCenter
SHIP2-SRC-β-catenin signaling axis sustains thymidylate synthase expression and promotes fluoropyrimidine resistance.
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