KLF5 activates ALPP to promote the proliferation of AR-null prostate cancer cells Open Access

Abstract

Prostate cancer is the second most lethal type of cancer for men in the United States, claiming almost 30,000 lives annually. Most prostate cancers initially depend on the presence of androgens for cell survival and proliferation, making them targetable by androgen deprivation therapy. However, prostate cancer at later stages often develop into androgen independent, including androgen receptor (AR) pathway-independent, variants, which are resistant to hormonal therapy and no other agents have yet been shown to be effective targets for treatment of these tumors. Ultimately, our goal is to identify prospective novel targets for the development of targeted therapies in AR pathway-independent prostate cancer to improve patient survival.Krüppel-like Factor 5 (KLF5) is a transcription factor that is expressed at lower levels but is rarely mutated in prostate cancers. In this study, we investigated the Placental Alkaline Phosphatase (ALPP) gene as a potential transcriptional target KLF5. RT-PCR and western blotting showed ALPP upregulation by KLF5. ChIP PCR and sequencing suggested that KLF5 bound directly to the promoter region of ALPP. To characterize the effects of the KLF5/ALPP axis on cell growth and chemosensitivity, we performed colony formation and cytotoxicity assays and found that ALPP was involved in cell proliferation, and that knockdown of ALPPreduced the pro-proliferative effects of KLF5. While KLF5 knockout also caused a decrease in cell proliferation and colony formation, such a decrease was rescued by ALPP overexpression. Preliminary cytotoxicity assays also suggest that ALPP expression may sensitize AR-null prostate cancer to docetaxel treatment. These results suggest that KLF5-regulated ALPP promotes cell growth and is involved in chemosensitivity. 

Table of Contents

Introduction…………………………………………………………………………………........................……..1

Results………………………………………………………………………………………..........................……..3

            Identification of candidate genes under KLF5 regulation………………..…..........…………….3

            Quantification of expression levels of 7 candidate genes………………………………..........…4

            KLF5 may bind to ALPP gene region and upregulate expression………………………............6 

            KLF5 promotes cell proliferation and contributes to maintenance of epithelial status…...9

            ALPP is necessary for cell proliferation and colony formation…………..........……………....11

            KLF5 alone does not induce docetaxel resistance..………………………….............….………..13  

            TGF-β induces docetaxel resistance mediated by KLF5 and reduces cell proliferation......15

            KLF5 mediatesTGF-β-induced chemoresistance…………………………….................……...…17 

            ALPP is involved in cell proliferation and may sensitize cells to chemoresistance….....….18

Discussion…………………………………………………………………………………............................…....21

Methods………………………………………………………………………………………................................24

Supplemental Figures……………………………………………………………………........................……...29

References……………………………………………………………………………………...........................…..30

About this Honors Thesis

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School	Emory College
Department	Biology
Degree	B.S.
Submission	Honors Thesis
Language	English
Keyword	KLF5
Committee Chair / Thesis Advisor	Dr. Jin-Tang Dong, Emory University
Committee Members	Dr. Kevin Karnes, Emory University Dr. Gregg Orloff, Emory University

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