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Single nucleotide polymorphism of IGF-1R (rs2229765) in acne and/or its severity
* Corresponding author: Dr. Dipankar De, Department of Dermatology, Venereology and Leprology, Postgraduate Institute of Medical Education and Research, Sector 12, Chandigarh-160012, India. dr_dipankar_de@yahoo.in
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Received: ,
Accepted: ,
How to cite this article: Kamboj P, Arora AK, Kaur R, Banerjee S, Dhawan G, Gupta N, et al. Single nucleotide polymorphism of IGF-1R (rs2229765) in acne and/or its severity. Ann Natl Acad Med Sci (India) 2024;60:294-6. doi: 10.25259/ANAMS-2023-4-11-(855)
Abstract
Acne vulgaris is a common inflammatory disease of pilosebaceous glands diagnosed by dermatologists in teenagers. During puberty, a peak in the levels of hormones (growth factors and its terminal mediator insulin-like growth factor-1 (IGF-1)) is observed that plays a vital role in acne pathogenesis. IGF-1 and its polymorphism are known to positively correlate with acne and/or its severity. However, the role of polymorphism of IGF-1 receptor (IGF-1R) in acne and/or its severity has not yet been elucidated. Therefore, the study aimed to assess the association of IGF-1R polymorphism with the occurrence of acne and its severity. IGF-1R polymorphism was analyzed in acne patients (n = 100) and controls (n = 100) by the restriction fragment length polymorphism. IGF-1R polymorphism was found to be evenly distributed among the controls and patients. Although IGF-1 polymorphism positively correlates with acne and/or its severity, the polymorphism of its receptor IGF-1R was not significantly associated with acne. Furthermore, no significant association was observed between IGF-1R polymorphism and IGF-1R expression at messenger ribonucleic acid (mRNA) and protein level. A similar study with a larger study populations may be planned to validate or refute the observed findings.
Keywords
Acne
genotype
IGF-1 receptor (IGF-1R)
Insulin like growth factor -1 (IGF-1)
single nucleotide polymorphism
INTRODUCTION
Acne vulgaris is a common inflammatory skin disease among adolescents.1 It is associated with elevated insulin-like growth factor-1 (IGF-1) level that exerts a wide range of biological effects1 via activation of its tyrosine kinase receptor (IGF-1R).2 IGF-1 level and its polymorphism positively correlate with acne and/or its severity.3 Studies in various carcinomas and autoimmune diseases have shown an important role of single nucleotide polymorphism (SNP) of IGF-1R (rs2229765).4 The role of IGF-1 in acne pathogenesis has been suggested by various studies, but the role of IGF-1R polymorphism in acne and/or its severity is still not established. In this study, we tried to assess whether an association exists between IGF-1R polymorphism and occurrence of acne or its severity.4
MATERIAL AND METHODS
The case–control study was conducted after approval from the Ethics Committee (Ref no. NK/2606/Study/116 dated 10.03.2016). Written informed consent was obtained from all the recruited patients and controls. Clinically confirmed patients with acne vulgaris (n = 100) were recruited after proper examination by an experienced dermatologist in daylight. An equal number of age and gender matched controls (n = 100), patients attending our outpatient department for another disease and not having acne, were recruited.
To study the polymorphism of IGF-1R, 2 ml venous blood sample was collected under aseptic precautions from all study participants in ethylenediaminetetraacetic acid (EDTA) vial for deoxyribonucleic acid (DNA) isolation using NucleoSpin® Blood DNA kits (Macherey-Nagel, Germany, REF 740951.250). The isolated DNA was amplified and digested overnight at 37°C by 1U Mn1I restriction enzyme (Thermo Scientific; Cat no-ER1071). Polyacrylamide gel electrophoresis (15%) was used to visualize the digested products on the Gel DOC System (Alpha Imager, USA) [Supplementary Figure 1].
For expression studies, two biopsies (2 mm) from any two facial acne lesions of acne patients (n = 100) were taken under local anesthesia. One of the biopsy samples was used to study the expression of IGF-1R at gene level and the other one was used to study the expression of IGF-1R at protein level. From healthy controls (n = 20), one facial skin biopsy was taken under local anesthesia to study the gene expression of IGF-1R. For gene expression studies, ribonucleic acid (RNA) was isolated by TRIzol (Thermo Invitrogen, Cat no. 15596026) and converted to complementary DNA (cDNA) (Verso cDNA synthesis kit by Thermo Scientific; Cat no. #AB-1453/A) followed by Real Time-Plymerase chain reaction (RT-PCR) (Thermo Scientific; Cat no–F-416X) using SYBR green. Protein expression was analyzed by immunohistochemistry using a primary antibody against IGF-1R in formalin-fixed sample (Biorad, Cat no. MCA2344) [Supplementary Figure 2].
Statistical tests were carried out using SPSS version 16.
RESULTS
The mean age of controls and cases were 24.24 ± 4.8 and 23.09 ± 5.8 years, respectively. The genotypic distribution of IGF-1R polymorphism in controls and cases was nearly the same, that is, 16.7% of controls and 16.3 % of cases exhibited homozygous AA genotype; 52.2% of controls and 57% of cases had homozygous GG genotype; and 26.7% and 31.1% controls and cases had heterozygous GA genotype respectively [Supplementary Figure 3]. The association between the genotypes and acne or its severity was analyzed using the Chi-square test. It was observed that none of the genotypes were associated with acne (likelihood ratio 0.476, p = 0.788) and/or its severity (p = 0.965). The mRNA expression of IGF-1R was found to be significantly decreased (p = 0.0418) in cases (0.46 ± 0.82, 95% CI 0.25–0.67) as compared to controls (1.52 ± 2.11, 95% CI 0.53 – 2.57) [Figure 1]. At the protein level, 66.6% of the acne cases showed IGF-1R positivity of grade 2+ and 3+. However, the effect of polymorphism on the expression of IGF-1R at the mRNA level (spearman correlation, r = 0.135, p = 0.25) or protein level (spearman correlation, r = 0.17, p = 0.11) in acne patients was not found to be significantly correlated.
DISCUSSION
IGF-1 interaction with IGF-1R initiates a downstream cascade that leads to the regulation of genes/factors required in acne pathogenesis.1,2 All three genotypes (homozygous AA and GG and heterozygous AG) were equally distributed between controls and cases, suggesting that IGF-1R polymorphism is not associated with acne or its severity. However, discrepancy observed at mRNA and protein levels suggests that transcript levels alone might not be sufficient to determine the protein expression.5 Furthermore, IGF-1R expression at mRNA and protein level was not associated with its polymorphism. Overall, it was inferred that IGF-1R polymorphism was not associated with acne and/or its severity, and IGF-1R genotype did not have an effect on the expression of IGF-1R at mRNA or tissue level. A formal sample size calculation was not done because of absence of data to do so. Sample size was limited by funds available. Results of this pilot study do not project a signal toward an association between IGF-1R polymorphism and acne or its severity. A similar study may be planned in a larger study population to validate or refute the observed findings.
CONCLUSION
IGF-1 and its polymorphism is known to play an important role in pathogenesis of acne and/or determines its severity. Binding of IGF-1 to its receptor (IGF-1R) initiates cascade of events that regulate genes/factors affecting acne pathogenesis. In our study, we observed that single nucleotide polymorphism (SNP) of IGF-1R was evenly distributed in controls and cases and was not associated with acne or its severity. Furthermore, no effect of IGF-1R polymorphism was observed at genetic and protein level. These findings suggest that IGF-1R polymorphism does not play any significant role in acne and/or its severity.
Authors’ contributions
PK: Data collection, analysis and interpretation, manuscript drafting; AKA: Recruitment of patients and healthy controls; NG: Sample collection; RK, SB and GD: Data collection; DD: Conceptualization, funding acquisition, patient recruitment, supervision, manuscript editing.
Acknowledgment
We acknowledge contribution of Dr. Arnab Pal (genetic analysis), Dr. Uma Nahar Saikia (immunohistochemistry) and Dr. Sanjeev Handa (patient recruitment).
Ethical approval
The research/study approved by the Review Board at Postgraduate Institute of Medical Education and Research, number NK/2606/Study/116, dated 10th March 2016.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent.
Financial support and sponsorship
Intramural Research Grant of Postgraduate Institute of Medical Education and Research, Chandigarh, India (Grant approval: 71/8-Edu-15/583 dated 05/04/2016).
Conflicts of interest
There are no conflicts of interest.
Use of artificial intelligence (AI)-assisted technology for manuscript preparation
The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.
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