Cancer Res Treat.  2019 Jan;51(1):313-325. 10.4143/crt.2018.105.

Diagnostic Significance of p38 Isoforms (p38α, p38β, p38γ, p38δ) in Head and Neck Squamous Cell Carcinoma: Comparative Serum Level Evaluation and Design of Novel Peptide Inhibitor Targeting the Same

• Sahu V
• Nigam L
• Agnihotri
• Gupta A
• Shekhar S
• Subbarao N
• Bhaskar S
• Dey S

• KMID: 2437622
• DOI: http://doi.org/10.4143/crt.2018.105

Abstract

PURPOSE
The p38 mitogen-activated protein kinase (MAPKs) play a crucial role in the production of pro-inflammatory cytokines and over-expression of it increase cytokines which promote cancer. Among four isoforms, p38α has been well studied in head and neck squamous cell carcinoma (HNSCC) and other cancers as a therapeutic target. p38δ has recently emerged as a potential disease-specific drug target. Elevated serum p38α level in HNSCC was reported earlier from our lab. This study aims to estimate the levels of p38 MAPK-isoforms in the serum of HNSCC and design peptide inhibitor targeting the same.
MATERIALS AND METHODS
Levels of p38 MAPK isoforms in the serum of HNSCC and healthy controls were quantified by surface plasmon resonance technology. The peptide inhibitor for p38 MAPK was designed by molecular modeling using Grid-based Ligand Docking with Energetics tools and compared with known specific inhibitors.
RESULTS
We have observed highly elevated levels of all four isoforms of p38 MAPK in serum of HNSCC patients compared to the control group. Further, serum p38α, p38β, and p38δ levels were down regulated after therapy in follow-up patients, while p38γ showed no response to the therapy. Present study screened designed peptide WFYH as a specific inhibitor against p38δ. The specific inhibitor of p38δ was found to have no effect on p38α due to great structural difference at ATP binding pocket.
CONCLUSION
In this study, first time estimated the levels of p38 MAPK isoforms in the serum of HNSCC. It can be concluded that p38 MAPK isoforms can be a diagnostic and prognostic marker for HNSCC and p38δ as a therapeutic target.

Keyword

Head and neck squamous cell carcinoma; Surface plasmon resonance; p38 isoforms; Peptide inhibitor; Serum; Molecular docking

MeSH Terms

Adenosine Triphosphate
Carcinoma, Squamous Cell*
Cytokines
Epithelial Cells*
Follow-Up Studies
Head*
Humans
Models, Molecular
Neck*
p38 Mitogen-Activated Protein Kinases
Protein Isoforms*
Protein Kinases
Surface Plasmon Resonance
Adenosine Triphosphate
Cytokines
Protein Isoforms
Protein Kinases
p38 Mitogen-Activated Protein Kinases

Figure

• 

  Fig. 1. Standard curve of pure recombinant p38 mitogen-activated protein kinase by surface plasmon resonance. (A) p38α. (B) p38β. (C) p38γ. (D) p38δ. Concentration of protein in control and head and neck squamous cell carcinoma (HNSCC) patient. Histogram of p38α (E), p38β (F), p38γ (G), and p38δ (H). Receiver operating characteristic analysis showing the area under curve (AUC) for p38α (I), p38β (J), p38γ (K), and p38δ (L) to distinguish HNSCC to healthy control subjects.

• 

  Fig. 2. Liginteraction of WFYH showing hydrogen bonding (dashed arrow) and hydrophic residue (green). (A) p38δ Lys-54, Pro-108, Met-110 (2), Lys116, Asp-168 and a π-π interaction between Trp of WFYH tera-peptide and Phe-169 of p38δ is shown by green solid arrow. (B) p38α hydrogen bonding residues are Gly-110, Asp-112, Asp-168 (2). (C) p38β: Asp-124, Glu-125 (4), Gln-128, Gly-276. (D) p38γ no hydrogen forming residue present.

• 

  Fig. 3. Docked pose of tera-peptide WFYH (green) with p38δ (white). (A) Surface structure of p38δ (white) with active site (yellow) and WFYH tera-peptide. (B) Ribbon structure of p38δ with tera-peptide WFYH; residues forming hydrogen bonds are labeled pink and hydrogen bonds are represented by red lines and corresponding distances in blue.

• 

  Fig. 4. Sensorgram showing concentration dependent binding of WFYH peptide with recombinant GST tag p38δ protein (resonance unit on y-axis and time in second on x-axis).

Reference

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