Negative feedback regulation of ErbB4 tyrosine kinase activity by ERK-mediated non-canonical phosphorylation

Identification of genes and pathways associated with sex in Non-smoking lung cancer population

INTRODUCTION

Women represent a higher proportion than men among those with lung cancer in nonsmokers compared to smokers. The reason for this abnormally higher proportion is not yet clear, but sex differences suggest there may be a genetic component at play.

MATERIALS AND METHODS

The gene expression determined by Illumina RNA Sequencing and the relevant clinical information of lung cancer patients was download from TCGA. The differentially expressed genes (DEGs) were screened between males and females in both nonsmoking and smoking populations. The top 50 validated DEGs are represented with heatmaps. Based on the DEGs, GO functional and KEGG pathway enrichment analyses were performed. PPI networks were constructed to further illustrate the direct and indirect associations among the DEGs. Survival analysis was performed to explore whether these genes can affect lung cancer patient prognosis.

RESULTS

In non-smoking patients, there were significantly more females than males (female 73.0% vs male 27.0%, P < 0.001). Such difference was not found in smoking patients (female 50.7% vs male 49.3%, P = 0.770). A total of 898 DEGs were identified in the non-smoking population, while a total of 992 DEGs were identified in the smoking population. Of these, only 122 genes were shared by both populations. Some pathways were enriched specifical in non-smoking population, such as cAMP signaling pathway and ovarian steroidogenesis. Several proteins related to estrogen function and MAPK/PI3K signaling, such as KRT16, ERBB4 and NTF4, showed differential effects on the lung adenocarcinoma progression in non-smoking males or females.

CONCLUSIONS

Some genetic differences between male and female in non-smoking lung adenocarcinoma patients have been identified. Potentially, ER signaling and MAPK/PI3K signaling partially participated in this discrepancy.

The Yin and Yang of ERBB4: Tumor Suppressor and Oncoprotein

ERBB4 (HER4) is a member of the ERBB family of receptor tyrosine kinases, a family that includes the epidermal growth factor receptor (EGFR/ERBB1/HER1), ERBB2 (Neu/HER2), and ERBB3 (HER3). EGFR and ERBB2 are oncoproteins and validated targets for therapeutic intervention in a variety of solid tumors. In contrast, the role that ERBB4 plays in human malignancies is ambiguous. Thus, here we review the literature regarding ERBB4 function in human malignancies. We review the mechanisms of ERBB4 signaling with an emphasis on mechanisms of signaling specificity. In the context of this signaling specificity, we discuss the hypothesis that ERBB4 appears to function as a tumor suppressor protein and as an oncoprotein. Next, we review the literature that describes the role of ERBB4 in tumors of the bladder, liver, prostate, brain, colon, stomach, lung, bone, ovary, thyroid, hematopoietic tissues, pancreas, breast, skin, head, and neck. Whenever possible, we discuss the possibility that ERBB4 mutants function as biomarkers in these tumors. Finally, we discuss the potential roles of ERBB4 mutants in the staging of human tumors and how ERBB4 function may dictate the treatment of human tumors. SIGNIFICANCE STATEMENT: This articles reviews ERBB4 function in the context of the mechanistic model that ERBB4 homodimers function as tumor suppressors, whereas ERBB4-EGFR or ERBB4-ERBB2 heterodimers act as oncogenes. Thus, this review serves as a mechanistic framework for clinicians and scientists to consider the role of ERBB4 and ERBB4 mutants in staging and treating human tumors.

A Review of HER4 (ErbB4) Kinase, Its Impact on Cancer, and Its Inhibitors

HER4 is a receptor tyrosine kinase that is required for the evolution of normal body systems such as cardiovascular, nervous, and endocrine systems, especially the mammary glands. It is activated through ligand binding and activates MAPKs and PI3K/AKT pathways. HER4 is commonly expressed in many human tissues, both adult and fetal. It is important to understand the role of HER4 in the treatment of many disorders. Many studies were also conducted on the role of HER4 in tumors and its tumor suppressor function. Mostly, overexpression of HER4 kinase results in cancer development. In the present article, we reviewed the structure, location, ligands, physiological functions of HER4, and its relationship to different cancer types. HER4 inhibitors reported mainly from 2016 to the present were reviewed as well.

ERK-mediated negative feedback regulation of oncogenic EGFRvIII in glioblastoma cells

Epidermal growth factor receptor variant III (EGFRvIII) is the most common active EGFR mutant in glioblastoma multiforme (GBM). The expression of this mutant often correlates with a poor patient prognosis due to its ability to extend downstream signaling. The EGFR pathway is controlled by a negative feedback mechanism that restricts the extent and length of downstream signaling. To date, the role of negative feedback in the oncogenic EGFRvIII mutant remains undetermined. The present study indicated that activation of the MEK-ERK pathway led to the phosphorylation of Thr-402, a conserved negative feedback residue in the juxtamembrane domain corresponding to Thr-669 of wild-type EGFR (EGFRwt), which resulted in a rapid reduction in the tyrosine phosphorylation of EGFRvIII in U87MG human glioblastoma and 293 cells. Moreover, despite the incapability of EGFRvIII to bind ligands, EGF was indicated to downregulate the tyrosine phosphorylation of EGFRvIII by activating the EGFRwt-ERK pathway. These results demonstrated a conserved negative feedback mechanism in the activation of EGFRvIII, which presents a new aspect in functional interactions between EGFRvIII and EGFRwt in glioblastoma cells.