IRE1alpha controls cyclin A1 expression and promotes cell proliferation through XBP-1

Area of Science:

• Molecular Biology
• Cancer Research
• Cellular Stress Response

Background:

• IRE1 (inositol-requiring enzyme 1) is a key regulator of the endoplasmic reticulum (ER) stress response in various organisms.
• Its precise functions in mammalian systems, particularly in cancer, remain incompletely understood.

Purpose of the Study:

• To investigate the role of IRE1alpha activity in prostate cancer cell lines.
• To determine the impact of IRE1alpha modulation on gene transcription, cell survival, and proliferation.

Main Methods:

• Utilized molecular and chemical genetic approaches to control IRE1alpha activity in prostate cancer cells.
• Examined gene transcription, cell survival, and proliferation.
• Employed siRNA to repress XBP-1 levels.
• Conducted genome-wide differential mRNA expression analysis.

Main Results:

• IRE1alpha activity did not affect the transcription of classical ER stress-response genes (Grp78, CHOP) or cell survival under ER stress.
• IRE1alpha activity positively correlated with cancer cell proliferation.
• Repressing XBP-1 levels significantly slowed proliferation.
• IRE1alpha induction enriched for ER-Golgi, plasma membrane, and secretory gene products.
• Cyclin A1 was the only differentially expressed cell cycle gene, with increased protein levels dependent on IRE1alpha and XBP-1.

Conclusions:

• IRE1alpha controls a specific subset of the ER stress response.
• IRE1alpha mediates prostate cancer cell proliferation through XBP-1 splicing.
• This pathway represents a potential therapeutic target in prostate cancer.