The Hippo/YAP pathway interacts with EGFR signaling and HPV oncoproteins to regulate cervical cancer progression.
Bottom Line: The Hippo signaling pathway controls organ size and tumorigenesis through a kinase cascade that inactivates Yes-associated protein (YAP).Our results suggest that YAP expression is associated with a poor prognosis for cervical cancer.Our study indicates that combined targeting of the Hippo and the ERBB signaling pathways represents a novel therapeutic strategy for prevention and treatment of cervical cancer.
Affiliation: Olson Center for Women's Health, Department of Obstetrics & Gynecology, University of Nebraska Medical Center, Omaha, NE, USA College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, China.Show MeSH
Related in: MedlinePlus
Mentions: Since YAP is overexpressed in cervical cancer, we used ME180 (HPV positive) and HT3 (HPV negative) cervical cancer cell lines to clarify the role of YAP in cervical cancer cell proliferation. We established six cell lines with differential YAP protein levels and activities: ME180-YAPS127A and HT3-YAPS127A cell lines expressing constitutively activated YAP; ME180-YAP and HT3-YAP overexpressing wild-type YAP; and ME180-MXIV and HT3-MXIV cells transfected with control vectors (MXIV). As expected, YAP was overexpressed in ME180-YAP, HT3-YAP, ME180-YAPS127A, and HT3-YAPS127A cells (Fig2A and C, Appendix Fig S3A and B). An increase in phosphorylated YAP was observed in the ME180-YAP and HT3-YAP cells, but not in ME180-YAPS127A and HT3-YAPS127A cells, consistent with the mutation of serine 127 to alanine (Fig2A and C, Appendix Fig S3A and B), which results in constitutive YAP activity (Pan, 2010). We observed that in the presence of complete medium (10% serum for HT3, 2.5% serum for ME180), the growth rate of the ME180 and HT3 cell lines was similar prior to reaching confluence. After reaching confluence (> 4 days after cell plating), cells in the control groups almost stopped proliferating. However, cells overexpressing YAP or YAPS127A continued to proliferate (Fig2B and D), with the highest growth rates observed in ME180-YAPS127A and HT3-YAPS127A cells. Interestingly, when examined under serum-reduced conditions (1% FBS), the growth rate of the ME180-YAPS127A cells was significantly higher than that of the ME180-YAP cells, while growth rate of the ME180-YAP cells was significantly higher than that of ME180-MXIV cells, even before the cell cultures reach confluence (Appendix Fig S3C). We then analyzed cell cycle progression in these cell lines after they reached confluence. The results showed that overexpression or constitutive activation of YAP increased the percentage of cells in S and G2/M phases, and reduced the proportion of cells in G1 phase in both ME180 and HT3 cervical cancer cells (Appendix Fig S4).
Affiliation: Olson Center for Women's Health, Department of Obstetrics & Gynecology, University of Nebraska Medical Center, Omaha, NE, USA College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, China.