Expression of STK11 gene and its promoter activity in MCF control and cancer cells

Asma Alkaf,Somaya Alqattan,Seema Zargar,Abdulaziz Al-Jafari,Tanveer A Wani

doi:10.1007/s13205-017-1000-6

Abstract

Serine/threonine kinase gene (STK11) is identified as tumor suppressor gene whose mutation can lead to Peutz–Jeghers syndrome (PJS). STK11 is emerging as a multifunctional protein, it activates 14 different AMP-activated protein kinase (AMPK) family members, important in the regulation of cell polarity, cell cycle arrest, energy and hemostasis. Present study was designed to evaluate STK11 mRNA expression in MCF-7 cancer and MCF-10 normal breast cells lines. mRNA expression was studied by real-time PCR. Further, human STK11 promoter construct was fused to a luciferase reporter and transfected into both MCF-7 and MCF-10 cells to identify the promoter activity in these cells. STK11 mRNA was found significantly higher in MCF-7 compared to MCF-10 cells (p value < 0.0005) indicating its role in the onset of breast cancer. Interestingly, it was found that the promoter activity of STK11 gene in MCF-7 cells was also significantly higher when compared to MCF-10 cells (p value < 0.005). Positive correlation was observed in promoter activity and gene expression (p = 0.048, r2 = 0.587). This study for the first time relates the altered STK11 gene expression in breast cancer cells with altered promoter activity. The present finding may shed light on the new therapeutic approaches against breast cancer by targeting gene or its promoter.

Highlights

Breast cancer is the most common cancer in women with approximately 1.15 million new cases diagnosed annually and increase in death rate with passing years becoming a significant problem worldwide
It was found that the promoter activity of STK11 gene in MCF-7 cells was significantly higher when compared to MCF-10 cells (p value \ 0.005)
Evaluation of STK11 mRNA levels in MCF-7 and MCF-10 cells showed that STK11 transcript was significantly more abundant in MCF-7 cells when compared to MCF-10 cells by reverse transcription PCR

Summary

Introduction

Breast cancer is the most common cancer in women with approximately 1.15 million new cases diagnosed annually and increase in death rate with passing years becoming a significant problem worldwide. STK11 protein, known as LKB1, is one of the protein kinase that encodes from STK11 gene and acts as a tumor suppressor. STK11 was discovered as a mutant gene in patients with Peutz–Jeghers syndrome (PJS) (Peutz 1921). The risk of developing breast cancer in PJS patients is 8% at the age of 40 and reaches 45% by the age of 70 (Hearle et al 2006). Mutations in STK11 gene have been found in patients of breast cancer without PJS. Loss of STK11 expression leads to papillary breast carcinoma (Esteller et al 2000). This shows that STK 11 gene is an important candidate to explore in breast cancer studies

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Conclusion