Upregulated Polo-Like Kinase 1 Expression Correlates with Inferior Survival Outcomes in Rectal Cancer

PLoS One. 2015 Jun 5;10(6):e0129313. doi: 10.1371/journal.pone.0129313. eCollection 2015.


Background: Human polo-like kinase 1 (PLK1) expression has been associated with inferior outcomes in colorectal cancer. Our aims were to analyse PLK1 in rectal cancer, and its association with clinicopathological variables, overall survival as well as tumour regression to neoadjuvant treatment.

Methods: PLK1 expression was quantified with immunohistochemistry in the centre and periphery (invasive front) of rectal cancers, as well as in the involved regional lymph nodes from 286 patients. Scores were based on staining intensity and percentage of positive cells, multiplied to give weighted scores from 1-12, dichotomised into low (0-5) or high (6-12).

Results: PLK1 scores in the tumour periphery were significantly different to adjacent normal mucosa. Survival analysis revealed that low PLK1 score in the tumour periphery had a hazard ratio of death of 0.59 in multivariate analysis. Other predictors of survival included age, tumour depth, metastatic status, vascular and perineural invasion and adjuvant chemotherapy. There was no statistically significant correlation between PLK1 score and histological tumour regression in the neoadjuvant cohort.

Conclusion: Low PLK1 score was an independent predictor of superior overall survival, adjusting for multiple clinicopathological variables including treatment.

MeSH terms

  • Aged
  • Cell Cycle Proteins / metabolism*
  • Chemoradiotherapy / methods
  • Female
  • Humans
  • Immunohistochemistry
  • Kaplan-Meier Estimate
  • Logistic Models
  • Male
  • Multivariate Analysis
  • Neoadjuvant Therapy / methods
  • Neoplasm Staging
  • Outcome Assessment, Health Care / methods*
  • Outcome Assessment, Health Care / statistics & numerical data
  • Prognosis
  • Proportional Hazards Models
  • Protein-Serine-Threonine Kinases / metabolism*
  • Proto-Oncogene Proteins / metabolism*
  • Rectal Neoplasms / metabolism*
  • Rectal Neoplasms / pathology
  • Rectal Neoplasms / therapy
  • Survival Analysis
  • Up-Regulation*


  • Cell Cycle Proteins
  • Proto-Oncogene Proteins
  • Protein-Serine-Threonine Kinases
  • polo-like kinase 1

Grant support

The authors have no support or funding to report.