The Human Intermediate Prolactin Receptor I-tail Contributes Breast Oncogenesis by Targeting Ras/MAPK Pathway

Area of Science:

• Molecular Biology
• Oncology
• Cell Biology

Background:

• Prolactin receptor (PRLr) and its variants are implicated in breast cancer.
• The intermediate form of human PRLr (hPRLrI) possesses a unique 13 amino acid I-tail.
• Coexpression of hPRLrL and hPRLrI is crucial for mammary epithelial transformation.

Purpose of the Study:

• To elucidate the functional role of the hPRLrI I-tail in prolactin receptor-mediated mammary oncogenesis.
• To investigate the I-tail's involvement in signaling pathways and gene expression.

Main Methods:

• Utilized MCF10AT cells engineered to express hPRLrL/hPRLrI or a mutant lacking the I-tail (hPRLrIΔ13).
• Assessed cell proliferation, anchorage-independent growth, and migration.
• Employed Western blot for signaling pathway analysis (Ras/MAPK, PI3K/Akt) and RNA-sequencing for gene expression profiling.

Main Results:

• Deletion of the I-tail significantly reduced cell proliferation, anchorage-independent growth, and attenuated cell migration.
• The I-tail was found to be involved in Ras/MAPK signaling, specifically impacting ERK activity, and influenced hPRLrI stability.
• RNA-sequencing revealed differential gene expression induced by prolactin upon I-tail removal; ERK1/2 inhibition decreased proliferation and colony formation.

Conclusions:

• The hPRLrI I-tail is a key contributor to breast oncogenesis, promoting proliferation, growth, and migration.
• Targeting the I-tail or its associated signaling pathways, such as ERK, presents a potential therapeutic strategy for breast cancer.
• Further research into the I-tail's mechanisms could lead to novel breast cancer treatments.