Angiogenin/Ribonuclease 5 Is an EGFR Ligand and a Serum Biomarker for Erlotinib Sensitivity in Pancreatic Cancer

An essential role of PRMT1-mediated EGFR methylation in EGFR activation by ribonuclease 5

Methylation at Arg198 and Arg200 residues of the EGFR extracellular domain by PRMT1 have been demonstrated to enhance EGFR activation by the canonical ligands, EGF and TGFα. On the other hand, RNase 5 was identified as a new ligand of EGFR recently. However, the interplay between EGFR methylation and RNase 5 in EGFR activation is still unclear. Here, we showed that RNase 5 activated EGFR and enhanced cell proliferation in colorectal cancer cells. PRMT1 positively regulated EGFR signaling activation by RNase 5. Inhibition of EGFR methylation by methylation-site mutagenesis reduced the binding affinity of RNase 5 to EGFR and abrogated RNase 5-mediated EGFR activation, suggesting that PRMT1-mediated EGFR methylation is critical for EGFR activation by RNase 5. Notably, RNase 5 diminished the inhibitory activity of cetuximab on colorectal cancer cells, implying RNase 5 is a potential biomarker to predict cetuximab response in colorectal cancer.

Distinct expression and prognostic value of members of the epidermal growth factor receptor family in ovarian cancer

Background

Increased aberrant expression or activation of the epidermal growth factor receptor (EGFR) family members has been reported in a wide range of cancers, and the EGFR family of tyrosine kinases has emerged as an important therapeutic target in malignancies. However, the expression patterns and exact roles of each distinct EGFR family member, which contribute to tumorigenesis and progression of ovarian cancer (OC), are yet to be elucidated.

Materials and methods

In the current study, we report the distinct expression and prognostic value of EGFR family members in patients with OC by analyzing a series of databases including ONCOMINE, Gene Expression Profiling Interactive Analysis, Kaplan-Meier plotter, cBioPortal, and Database for Annotation, Visualization and Integrated Discovery .

Results

It was found that in patients with OC, mRNA expression levels of ERBB2/3/4 were significantly upregulated, whereas the transcription levels of EGFR were downregulated. Aberrant EGFR expression and ERBB2/3/4 mRNA levels were associated with OC prognosis.

Conclusion

These results suggest that EGFR and ERBB3/4 are distinct prognostic biomarkers and may be potential targets for OC. These results may be beneficial to better understand the molecular underpinning of OC and may be useful to develop tools for more accurate OC prognosis and for promoting the development of EGFR-targeted inhibitors for OC treatment.

Incense burning smoke sensitizes lung cancer cells to EGFR TKI by inducing AREG expression

Incense burning is common in Asian countries due to the religious beliefs. Environmental exposure to incense burning smoke is a potential risk factor for tumor development and progression of non-small cell lung cancer (NSCLC). Eastern Asia ethnic origin is strongly associated the clinical benefits of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in NSCLC patients. However, the impact of the oriental custom of incense burning on the cancer progression and the EGFR TKI-sensitivity of NSCLC remains unclear. Our results showed that long-term exposure to incense burning extract (IBE) increases the cellular proliferation with S phase accumulation and the motility activity of NSCLCs. Interestingly, IBE enhances EGFR signaling activity without affecting its genetic status, and increases the cellular sensitivity of NSCLC cell lines to EGFR TKIs. Auramine, a yellow dye for making incense sticks, was identified as a residual composition in the burning incense smoke, and showed similar EGFR TKI-sensitizing effects. Furthermore, IBE or auramine transcriptionally induce EGFR ligand amphiregulin (AREG) expression for the enhancement of EGFR activity. Neutralization of AREG reduced the viability of IBE-treated cells. These results indicated that exposure to incent smoke may enhance NSCLC progression and their sensitivity to EGFR TKIs through increasing their oncogenic addiction to AREG-induced EGFR signaling.

RNase A Promotes Proliferation of Neuronal Progenitor Cells via an ERK-Dependent Pathway

Members of the ribonuclease A (RNase A) superfamily regulate various physiological processes. RNase A, the best-studied member of the RNase A superfamily, is widely expressed in different tissues, including brains. We unexpectedly found that RNase A can trigger proliferation of neuronal progenitor cells (NPC) both in vitro and in vivo. RNase A treatment induced cell proliferation in dissociated neuronal cultures and increased cell mass in neurosphere cultures. BrdU (5-Bromo-2'-Deoxyuridine) labeling confirmed the effect of RNase A on cell proliferation. Those dividing cells were Nestin- and SOX2-positive, suggesting that RNase A triggers NPC proliferation. The proliferation inhibitor Ara-C completely suppressed the effect of RNase A on NPC counts, further supporting that RNase A increases NPC number mainly by promoting proliferation. Moreover, we found that RNase A treatment increased ERK phosphorylation and blockade of the ERK pathway inhibited the effect of RNase A on NPC proliferation. Intracerebroventricular injection of RNase A into mouse brain increased the population of 5-ethynyl-2'-deoxyuridine (EdU) or BrdU-labeled cells in the subventricular zone. Those RNase A-induced NPCs were able to migrate into other brain areas, including hippocampus, amygdala, cortex, striatum, and thalamus. In conclusion, our study shows that RNase A promotes proliferation of NPCs via an ERK-dependent pathway and further diversifies the physiological functions of the RNase A family.

The Immunomodulatory and Antimicrobial Properties of the Vertebrate Ribonuclease A Superfamily

The Ribonuclease A Superfamily is composed of cationic peptides that are secreted by immune cells and epithelial tissues. Although their physiological roles are unclear, several members of the vertebrate Ribonuclease A Superfamily demonstrate antimicrobial and immune modulation activities. The objective of this review is to provide an overview of the published literature on the Ribonuclease A Superfamily with an emphasis on each peptide’s regulation, antimicrobial properties, and immunomodulatory functions. As additional insights emerge regarding the mechanisms in which these ribonucleases eradicate invading pathogens and modulate immune function, these ribonucleases may have the potential to be developed as a novel class of therapeutics for some human diseases.

A novel ligand-receptor relationship between families of ribonucleases and receptor tyrosine kinases

Pancreatic ribonuclease is known to participate in host defense system against pathogens, such as parasites, bacteria, and virus, which results in innate immune response. Nevertheless, its potential impact to host cells remains unclear. Of interest, several ribonucleases do not act as catalytically competent enzymes, suggesting that ribonucleases may be associated with certain intrinsic functions other than their ribonucleolytic activities. Most recently, human pancreatic ribonuclease 5 (hRNase5; also named angiogenin; hereinafter referred to as hRNase5/ANG), which belongs to the human ribonuclease A superfamily, has been demonstrated to function as a ligand of epidermal growth factor receptor (EGFR), a member of the receptor tyrosine kinase family. As a newly identified EGFR ligand, hRNase5/ANG associates with EGFR and stimulates EGFR and the downstream signaling in a catalytic-independent manner. Notably, hRNase5/ANG, whose level in sera of pancreatic cancer patients, serves as a non-invasive serum biomarker to stratify patients for predicting the sensitivity to EGFR-targeted therapy. Here, we describe the hRNase5/ANG-EGFR pair as an example to highlight a ligand-receptor relationship between families of ribonucleases and receptor tyrosine kinases, which are thought as two unrelated protein families associated with distinct biological functions. The notion of serum biomarker-guided EGFR-targeted therapies will also be discussed. Furthering our understanding of this novel ligand-receptor interaction will shed new light on the search of ligands for their cognate receptors, especially those orphan receptors without known ligands, and deepen our knowledge of the fundamental research in membrane receptor biology and the translational application toward the development of precision medicine.

Current Therapeutic Options for Pancreatic Ductal Adenocarcinoma

Pancreatic cancer remains the fourth most common cause of cancer-related mortality and is a major health threat. The majority of cases are diagnosed at advanced disease stages, limiting the chances of long-term survival. Several new therapeutic regimens have been introduced into routine clinical practice in recent years and a plethora of novel approaches is currently undergoing preclinical and early clinical evaluation. This review discusses the current standards of care for systemic therapy of pancreatic cancer and gives a brief outlook on ongoing clinical trials.

RNase moonlights as a cancer instigator

RNase 5 is a bona fide EGFR ligand that promotes oncogenic transformation in pancreatic cancer.