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p21-Activated Kinases 1, 2 and 4 in Endometrial Cancers: Effects on Clinical Outcomes and Cell Proliferation

Michelle K Y Siu1, Daniel S H Kong2, Sheila Y P Ngai2

  • 1Department of Pathology, The University of Hong Kong, Hong Kong, HKSAR, China; Department of Obstetrics and Gynaecology, The University of Hong Kong, Hong Kong, HKSAR, China.

Plos One
|July 29, 2015
PubMed

Insights

p21-activated kinases (Paks) are key in tumor progression. Pak1 and Pak4 show altered expression in endometrial cancer, with Pak1 promoting proliferation and cytoplasmic Pak4 serving as a potential prognostic marker.

Area of Science:

  • Oncology
  • Molecular Biology
  • Cell Biology

Background:

  • p21-activated kinases (Paks) are serine/threonine protein kinases implicated in malignant tumor progression.
  • Understanding the role of specific Paks in endometrial cancer pathogenesis is crucial for developing targeted therapies.

Purpose of the Study:

  • To investigate the expression of Pak1, p-Pak2, Pak4, and p-Pak4 in normal endometrium, hyperplastic endometrium, and endometrial cancer.
  • To correlate Pak expression with clinicopathological parameters and patient survival.
  • To elucidate the functional role of Pak1 in endometrial cancer cell proliferation and its downstream targets.

Main Methods:

  • Immunohistochemistry was used to assess the expression of Pak1, p-Pak2 Ser20, Pak4, and pPak4 Ser474 in endometrial tissue samples.
  • Expression levels were correlated with clinicopathological parameters such as histological grade, myometrial invasion, and patient survival.
  • Functional studies involved knockdown of Pak1 and Pak4 in an endometrial cancer cell line to assess effects on cell proliferation and downstream targets like cyclin D1, ERα, and PR.

Main Results:

  • Pak1, cytoplasmic and nuclear Pak4, and nuclear p-Pak4 were significantly overexpressed in endometrial cancer compared to atrophic endometrium.
  • Type I endometrioid carcinomas exhibited higher Pak1 expression than type II non-endometrioid carcinomas.
  • Pak1, Pak4, and p-Pak4 expression negatively correlated with histological grade, while p-Pak2 and cytoplasmic Pak4 inversely correlated with myometrial invasion.
  • Lower cytoplasmic Pak4 expression was associated with poorer patient survival, identifying it as an independent prognostic factor.
  • Knockdown of Pak1 reduced cell proliferation and the expression of cyclin D1, ERα, and PR in endometrial cancer cells.

Conclusions:

  • Pak1 and cytoplasmic p-Pak2 may drive normal endometrial proliferation during the menstrual cycle.
  • Pak1, Pak4, and p-Pak4 are involved in endometrial cancer pathogenesis, particularly in postmenopausal women.
  • Pak1 promotes endometrial cancer cell proliferation, especially in type I endometrioid carcinoma.
  • Cytoplasmic Pak4 is a potential prognostic marker for endometrial cancer.

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