Publication Date

2023

Document Type

Thesis

Committee Members

Weiwen Long, Ph.D. (Advisor); Kwang-Jin Cho, Ph.D. (Committee Member); Michael Craig, Ph.D. (Committee Member)

Degree Name

Master of Science (MS)

Abstract

Extracellular signal related kinase 3 (ERK3) is one of the atypical mitogen activated protein kinases (MAPK). It is expressed ubiquitously and plays a role in a variety of cellular processes, including cell growth and differentiation. ERK3’s role in promoting migration and invasion in various cancers has been well established. ERK3 is upregulated in non-small cell lung cancers (NSCLCs) and has been shown to promote NSCLC tumor growth and progression. However, the regulation of ERK3 in lung cancers remains largely unclear. A recent study indicates that ERK3 phosphorylation at S189, an indicator of ERK3 activity, is upregulated by KRAS in NSCLCs. KRAS is one of the most commonly mutated oncogenes in lung cancers. To study the KRAS dependent regulation of ERK3, knockdown of KRAS was performed and it resulted in a remarkable reduction in ERK3 phosphorylation as well as total ERK3 protein level confirming the regulation of ERK3 by KRAS. Upon knockdown of KRAS a significant reduction of ERK3 mRNA level was observed indicating that KRAS regulates ERK3 at transcriptional level. Further, we found that the regulation of ERK3 by KRAS may be through the transcription factor c-Jun, that is well-known to be activated by KRAS signalling. Our data indicates that c-Jun positively regulates ERK3 transcription in LUAD cell lines. Further, we have found that KRAS upregulates c-Jun activating phosphorylations in LUAD cells, suggesting that KRAS regulates ERK3 through c-Jun. Given the discrepancy regarding the role of ERK3 in NSCLC cell growth reported in previous studies, we have thoroughly investigated the role of ERK3 in cell growth by stable knockdown of ERK3 using shRNA targeting different regions of ERK3 mRNA, as well as by using ERK3 inhibitors in a variety of NSCLS cell lines. While knockdown of ERK3 via targeting the coding region did not affect cell proliferation, targeting the 3’UTR of ERK3 or treatment with ERK3 inhibitors reduced the proliferation of LUAD cells.

Page Count

65

Department or Program

Department of Biochemistry and Molecular Biology

Year Degree Awarded

2023

Download


Share

COinS