PC remains a major public health problem worldwide, posing a serious threat to the health of men all over the world28. PC continues to be the number one cause of cancer-related morbidity in many countries29. As a result, early diagnosis and timely treatment are especially important in reducing prostate cancer mortality. Recently ,miRNAs have been affirmed to be dysregulated in expression in many tumor tissues30, while playing an important role in the growth, proliferation and metastasis of various tumors 31. At the same time, miRNA has been found to be a potential biological marker for various cancers due to its stable presence in the blood, its availability by non-invasive examination only, and its easily detectable expression level19. In our study, to find the serum mir with the highest diagnostic value in PC, we designed a 3-stage study. A diagnostic panel consisting of 3 miRNAs was constructed by expanding the sample step by step through screening and validation. It allows for better screening and diagnosis of prostate cancer (AUC = 0.899; 95% CI: 0.843–0.941; sensitivity = 85.37%, specificity = 82.93%).
In our diagnostic panel, let-7b-5p has the highest diagnostic value (AUC = 0.832; 95% CI: 0.766 to 0.886). Even before us, let-7b-5p was shown to be remarkable regulated in cancerous tissues compared to the adjacent normal prostate epithelium, confirming the ability of mir to be a potential biomarker32. let-7b-5p can also regulate M2 polarization through the SOCS1/STAT pathway and reverse M2 differentiation to enhance macrophage phagocytosis. Ultimately, it inhibits the proliferation of PC cells33. Therefore, let-7b-5p has the potential to be a therapeutic target for PC. A study by Jentai Lin et al. discovered that the expression level of let-7b-5p were significantly higher in the urine of patients with bladder cancer and could be a promising non-invasive biomarker to diagnose bladder cancer34. For let-7b-5p in the urine of PC patients, this is also worth exploring.
Another miRNA in our panel is miR-15a-5p. A Study Shows miR-15a-5p reverses the effects of PVT1 Interference and Inhibits the Effects of KIF23 Knockdown to affect the progression of PC35. So miR-15a-5p may be a new biomarker for the treatment of PC. Early studies have demonstrated the potential of circulating miR-15a-5p as a diagnostic biomarker for endometrial cancer36 and non-small cell lung cancer37. Our research refines the diagnostic value of miR-15a-5p in prostate cancer.
Numerous researchers have revealed that mir-15b-5p not only promotes the progression of PC cells by targeting RECK38, but also exacerbates the progression of prostate cancer by inhibiting LATS239. Thus, mir-15b-5p usually plays an oncogenic role in PC, and the expression level is remarkable upregulated in cancer tissues. This is consistent with the expression level of serum mir-15b-5p in our experiments.
To look into the potential mechanism functions of let-7b-5p, miR-15a-5p, and mir-15b-5p, we selected target genes from miRWalk3.0 that were predicted by more than two miRNAs for bioinformatic analysis. The conclusions showed that these targets of aberrantly regulated miRNAs were related to numerous important cancer-related biological processes and pathways, such as oxytocin signaling pathway, Ubiquitin mediated proteolysis, and apelin signaling pathway. A recent study showed that oxytocin can cause PC cells to migrate40. In pancreatic cancer, upregulated apelin signaling activates oncogenic signaling pathways to promote tumor development. Apelinergic system appears as a promising target for cancer therapy41. Therefore, upregulated apelin signaling also appears to be a worthwhile therapeutic target in PC.
Under the criterion of p-value < 0.01 and |log2FC| Cutoff > 2 based on the expression level, we identified FAM107A and TAF1C through GEPIA database as attainable target genes for three-miRNA panel from genes predicted by three miRNAs simultaneously. FAM107A is a protein-coding gene that inhibits proliferation and induces apoptosis in kidney cancer cells42.AS reported by Yunfei Ma et al. ,FAM107A was an independent risk factor for progression-free survival in PC, showing its value in the diagnosis and prognosis of prostate cancer43. Many investigations have demonstrated the potential of FAM107A to be a therapeutic target for colon cancer and pancreatic cancer44,45, and its value in prostate cancer remains to be explored. Currently, there is a lack of research on TAF1C in prostate cancer. A study shows that TAF1C is associated with gastric and colorectal carcinogenesis through a combination of somatic frameshift mutations and intratumorally heterogeneity46. As to whether it is related to in the development of prostate cancer there is a lack of reliable experiments.
Although the miRNA panel constructed in our study is meaningful, there are still some shortcomings. It is one-side for us to select only 10 miRNAs in the screening phase and might lead us to overlook other meaningful mir in the serum. Our study sample consisted of only 112 prostate cancer patients and was confined to one region, which may have made a difference.