2.1 Data extraction
The original datasets comparing the gene expression profiles of the granulosa cells between PCOS patients and normal controls were downloaded from NCBI GEO databases (Table 1). The accession number was GSE34526(https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE34526), GSE80432 (https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE80432), GSE137684(https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE137684) respectively. The microarray data of GSE34526 was based on GPL570 ([HG-U133_Plus_2] Affymetrix Human Genome U133 Plus 2.0 Array), GSE80432 were based on GPL6244 and GSE137684 ([HuGene-1_0-st] Affymetrix Human Gene 1.0 ST Array [transcript (gene) version]) were based on GPL17077 (Agilent-039494 SurePrint G3 Human GE v2 8x60K Microarray 039381). The chip contains 23 PCOS patients and 15 healthy individuals. This study will examine the mRNA in ovarian granulosa cells from PCOS patients and healthy persons. The analytic workflow was shown in Figure 1.
Table 1: The basic backgrounds of the datasets included.
|
Platforms
|
Country
|
Year
|
NP
|
NC
|
GSE34526
|
[HG-U133_Plus_2] Affymetrix Human Genome U133 Plus 2.0 Array
|
China
|
2011
|
7
|
3
|
GSE80432
|
[HuGene-1_0-st] Affymetrix Human Gene 1.0 ST Array
|
China
|
2021
|
8
|
8
|
GSE137684
|
Agilent-039494 SurePrint G3 Human GE v2 8x60K Microarray 039381
|
China
|
2019
|
8
|
4
|
1. Number of PCOS Sample(NP);2. Number of Control Sample(NC)
2.2 Data pre-processing
The three raw datasets were pre-processed by “limma”, “sva” in R, including merge, background calibration, normalization.
2.3 Immune Infiltration Analysis
We investigated for a correlation between the hub gene expression and immune infiltration in PCOS. By ssGSEA in R, the infiltration of 29 immune cells that were obtained by GSEA download (https://www.gsea-msigdb.org/gsea/index.jsp)was analysed, with the ssGSEA score set as the standard and visualized using heat map generated by the “pheatmap” package. The “corrplot” package was employed to reveal the correlation among immune cells and immune cell functions regulators. The immune cells and immune cell functions between PCOS and normal groups were visualized by “ggpubr” package. Analyze the original data and take p<0.05 and | logFC |>0.5 as the screening conditions
2.3 Bioinformatics Analysis of curoptosis and m7G
We found 29 m7G-related genes and 13 curoptosis-related genes from previous systematic reviews [6, 11, 12]. The correlation between immune related gene matrix, curoptosis genes matrix and m7G related gene matrix was analyzed by "ggcorrplot", "ROCR" package, and a clinical prediction model was constructed and drew a correlation heat map.
2.4 Functional Enrichment Analyses
Since the number of key genes we obtained is small, we chose to conduct online analysis of KEGG and GO Enrichr database (https://maayanlab.cloud/Enrichr/). The difference was statistically significant at p < 0.05.
2.5 Experimental Validation
The Chengdu Xinan Women's Hospital provided the follicular fluid for this validation test, and three patients with polycystic ovary syndrome and three healthy volunteers signed an informed consent form. By centrifuging granular cells from the follicular fluid, quantitative real-time PCR (qRT-PCR) was utilized to confirm the expression of two sets of important genes.
2.5.1 Inclusion Criteria
1. The PCOS group met the Rotterdam diagnostic criteria[13]: ①. Rare ovulation and / or no ovulation;②. There is clinical and / or biochemical evidence of androgen excess; ③. Ultrasound showed polycystic ovary [12 or more follicles with a diameter of 2-9mm and/or ovarian volume increased (>10mL) in one ovary; calculation formula: 0.5 × high × wide × Thick)]. (2 of the 3 standards need to be satisfied).
2. In the normal group, patients with blocked fallopian tubes and normal ovarian function were selected.
3. Patients aged 20-35 years who need artificial assisted reproductive technology
(ART).
4. Patients using an antagonist regimen during the stimulation cycle.
2.5.2 Exclusion Criteria
1. The patients at the post refused to sign consent forms;
2. Patients with cardiovascular, immune, nervous system and other diseases;
3. Patients with ovarian cancer, ovarian cysts, and other ovarian disorders.
2.5.3 Granular Cells (GCs) Extraction
At the Chengdu Southwest Gynecological Hospital, follicular fluid from patients undergoing controlled ovulation induction was collected and centrifuged at 1500 rpm for five minutes. Follicular fluid makes up the supernatant, and GCs, red blood cells, and white blood cells make up the precipitate. Generating and mixing the precipitate with a tiny amount of follicular fluid is followed by centrifuging it at 3000 rpm for 10 minutes, absorbing the upper white layer as GCS after centrifugation, and then washing it twice with PBS.
2.5.4 Quantitative Real-Time PCR
In preparation for further analysis, the GCs from PCOS and normal individuals were extracted, added to RNA protection solution, and then frozen at -80°C. The total RNA was extracted by the TRIzol method. All reagents are purchased from Beijing Baori Medical Biotechnology Co., Ltd. TRIzol reagent was used to extract the total RNA from granulosa cells. Total RNA was reverse transcribed into cDNA using a template of 1μG. 40 °C for 60 min, 25 °C for 5 min, and 75 °C for 5 min were the reaction temperatures. GAPDH was utilized as an internal control after 1 L of cDNA was setup using an RTFQ-PCR system, and the RT-PCR amplification settings were set to 95 °C for 3 minutes, 40 cycles at 95 °C for 5s, and 60 °C for 32s. The primers used are as follows: NUDT16 (forward 5′- TCCCAATTTCCTCTTCTCCCAAAGC -3′, reverse 5′- GATCACGATCCCAACTCCACCAAG -3′) and DATL (forward 5′- GGGTTATTGCACAGCGATTAAT -3′, reverse 5′- GAAGAATTTGCTTCGGGAACTT -3′). After amplification, the relative expression amount is 2- ΔΔ Ct method calculation.
2.6 Statistical analysis
All statistical analyses were performed in the R language (Version 4.1.3). All statistical tests were bilateral, and p< 0.05 was considered statistically significant.