Determination of the Degradation Products of Pheomelanin as Potential Biomarker for Early-Stage Melanoma by Gas Chromatography-Mass Spectrometry (GC-MS)

Abstract

The pheomelanin precursor 5-S-cysteinyldopa (5SCD) exhibits promising potential as a urinary and serum biomarker for melanoma. Nonetheless, it is important to note that 68.8% of early-stage melanoma cases remained undetected when employing 5SCD as a biomarker, underscoring the inadequacy of its efficacy, especially in identifying stage I/II melanoma. In lieu of detecting free 5SCD, the hydrolysis products of pheomelanin, namely, 4-amino-3-hydroxyphenylalanine (4-AHP) and 3-amino-4-hydroxyphenylalanine (3-AHP) offer the prospect of achieving heightened sensitivity and broader scope in early-stage melanoma diagnosis through direct chemical processes. This study introduces an innovative gas chromatography-mass spectrometry (GC-MS) methodology to identify early-stage melanoma by comparing the concentrations of AHPs across 80 stage I/II melanoma patients against 32 healthy controls. The approach demonstrated linear response within the 0.5–20 μg/mL range for reference AHPs detection. The urine levels of AHPs were 1.3 ± 0.5 μg/mL in the control/volunteer group (n = 32), 8.1 ± 1.6 μg/mL in stage I and II melanoma patients (n = 28), and 6.3 ± 1.9 μg/mL in stage II melanoma patients (n = 52). The findings unequivocally underscore the diagnostic promise of AHPs as a robust tool for early-stage melanoma assessment in laboratory medicine.

Keywords:

• 4-Amino-3-hydroxyphenylalanine (4-AHP) and 3-amino-4-hydroxyphenylalanine (4-AHP and 3-AHP) (AHPs)
• 5-S-cysteinyldopa 5SCD
• gas chromatography-mass spectrometry (GC-MS)
• stage I/II melanoma

Acknowledgments

Sample collection was performed at the Geisinger Medical Center—Laboratory Medicine. 100 North Academy Avenue, Danville, PA 17822, and Geisinger Commonwealth School of Medicine Scranton.

Ethical approval

This clinical research and patient recruitment followed these ethics and regulations: Nuremberg Code (1947), Declaration of Helsinki (2000), Belmont Report (1979), CIOMS (2002), U.S. Common Rule (1991). There are seven main principles that have been applied for this clinical research and patient recruitment.

Reviewed by Institutional Review Board

NAME: Geisinger Institutional Review Board

IRB REGISTRATION #: 00008345

INSTITUTION: Geisinger Clinic

FWA ASSURANCE: FWA00000063

ACCREDITATION: Geisinger Health System is accredited by the Association for the Accreditation of Human Protection Programs, Inc. (AAHRPP)

ADDRESS: Geisinger Institutional Review Board, 100 North Academy Avenue. Danville, PA 17822-3069.

Informed consent was obtained from all individuals included in this study.

Author contributions

All data generation, collection and analysis were done by Wenhan Cheng. All urine samples were collected from Geisinger Medical Center - Laboratory Medicine, Pennsylvania. The sample collection was done by Dr. JianHong Lee (Geisinger Medical Center, stage I melanoma specimen, n = 28, stage II melanoma, n = 52) and Dr. Byran Jakson (Geisinger Commonwealth School of Medicine Scranton, volunteer specimens, n = 32.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

Funding was obtained from the Hematology Oncology Cancer Center GWV, 1000 E Mountain Blvd, Wilkes-Barre, PA 18711.