MCM3 upregulation confers endocrine resistance in breast cancer and is a predictive marker of diminished tamoxifen benefit.
Sanne LøkkegaardDaniel EliasCarla L AlvesMartin V BennetzenAnne-Vibeke LænkholmMartin BakMorten F GjerstorffLene E JohansenHenriette VeverChristina BjerreTove KirkegaardBo NordenskjöldTommy FornanderOlle StålLinda S LindströmLaura J EssermanAnne E LykkesfeldtJens S AndersenRikke Leth-LarsenHenrik Jørn DitzelPublished in: NPJ breast cancer (2021)
Resistance to endocrine therapy in estrogen receptor-positive (ER+) breast cancer is a major clinical problem with poorly understood mechanisms. There is an unmet need for prognostic and predictive biomarkers to allow appropriate therapeutic targeting. We evaluated the mechanism by which minichromosome maintenance protein 3 (MCM3) influences endocrine resistance and its predictive/prognostic potential in ER+ breast cancer. We discovered that ER+ breast cancer cells survive tamoxifen and letrozole treatments through upregulation of minichromosome maintenance proteins (MCMs), including MCM3, which are key molecules in the cell cycle and DNA replication. Lowering MCM3 expression in endocrine-resistant cells restored drug sensitivity and altered phosphorylation of cell cycle regulators, including p53(Ser315,33), CHK1(Ser317), and cdc25b(Ser323), suggesting that the interaction of MCM3 with cell cycle proteins is an important mechanism of overcoming replicative stress and anti-proliferative effects of endocrine treatments. Interestingly, the MCM3 levels did not affect the efficacy of growth inhibitory by CDK4/6 inhibitors. Evaluation of MCM3 levels in primary tumors from four independent cohorts of breast cancer patients receiving adjuvant tamoxifen mono-therapy or no adjuvant treatment, including the Stockholm tamoxifen (STO-3) trial, showed MCM3 to be an independent prognostic marker adding information beyond Ki67. In addition, MCM3 was shown to be a predictive marker of response to endocrine treatment. Our study reveals a coordinated signaling network centered around MCM3 that limits response to endocrine therapy in ER+ breast cancer and identifies MCM3 as a clinically useful prognostic and predictive biomarker that allows personalized treatment of ER+ breast cancer patients.
Keyphrases
- cell cycle
- estrogen receptor
- breast cancer cells
- cell proliferation
- poor prognosis
- clinical trial
- squamous cell carcinoma
- endoplasmic reticulum
- bone marrow
- drug delivery
- combination therapy
- signaling pathway
- study protocol
- adipose tissue
- metabolic syndrome
- dna methylation
- transcription factor
- cancer therapy
- long non coding rna
- neoadjuvant chemotherapy
- health information
- skeletal muscle
- amino acid
- dna damage response