1 Introduction

Prostate cancer (PCa) poses a serious challenge to men's health, characterized by malignant growth within the prostate. This disease ranks second in the global incidence of cancer in men [1]. Notably, in recent years, the incidence of PCa has gradually increased in China, with a higher prevalence observed in urban areas compared to rural regions. This demographic shift highlights the evolving trends in PCa epidemiology and emphasizes the importance of targeted screening measures to effectively meet the needs of different populations. Of concern is the higher risk faced by individuals aged 65 years and older, who often have advanced PCa at the time of diagnosis [2, 3]. This demographic vulnerability highlights the urgent need for proactive screening efforts, particularly for older men, to promote early detection and timely intervention to improve treatment outcomes and reduce mortality. Despite the availability of multiple diagnostic methods such as prostate-specific antigen (PSA) testing, clinical staging, and Gleason scoring, accurately predicting disease progression and guiding clinical treatment remain a major challenge. Although PSA level is a widely used biomarker in PCa testing, the traditional threshold of 4 ng/ml has limitations in sensitivity and may lead to missed diagnoses [4]. Therefore, there is an urgent need for more nuanced and comprehensive methods for PCa diagnosis and risk stratification. Innovative technologies such as genomic analysis and liquid biopsy are expected to improve the accuracy and reliability of PCa diagnosis. By analyzing genetic alterations and circulating tumor biomarkers, these cutting-edge approaches can provide valuable insights into tumor biology and disease progression, paving the way for more personalized therapeutic strategies based on individual patient needs.

The biological significance of miRNAs in tumorigenesis has garnered considerable attention in recent years. A burgeoning body of evidence underscores the involvement of miRNAs in the pathogenesis of various malignant tumors, including PCa [5,6,7,8]. Consequently, miRNAs play a pivotal role in facilitating the diagnosis, precision treatment, and prognosis management of these diseases. In response to the intricate molecular landscape of PCa, our research team developed the Qilan Formulation (patent No.: ZL 201310492315.8), grounded in the understanding of PCa pathogenesis characterized by the “imbalance of qi and blood, and complex coexistence of cold and heat.” We have substantiated that the Qilan Formulation exhibits notable efficacy in both the prevention and treatment of PCa. This compound formulation, derived from traditional Chinese medicine (TCM), exerts its therapeutic effects through the modulation of multiple targets, thereby achieving comprehensive regulatory effects. Building upon the recognized role of miRNAs in PCa progression, we hypothesized that TCM may influence PCa proliferation, invasion, metastasis, and apoptosis by modulating the miRNA-mediated signaling pathway. Accordingly, this article provides a concise overview of miRNA expression patterns and their applications in PCa diagnosis and TCM treatment. By synthesizing existing literature, our aim is to furnish valuable literature support for ongoing research endeavors in this domain.

2 Overview of miRNAs

MicroRNAs are short, single-stranded, noncoding RNA molecules typically comprised of 20–24 nucleotides. These molecules are encoded by endogenous genes and are ubiquitously present in eukaryotic organisms. The biogenesis of miRNAs begins with the transcription of miRNA genes into primary RNA (Pri-RNA) in the nucleus by RNA polymerase II. Subsequently, these Pri-RNAs are cleaved into precursor miRNAs (pre-miRNAs), which adopt a hairpin-like structure, by the Nuclear RNase III Drosha. The pre-miRNAs are then transported from the nucleus to the cytoplasm by the export protein exportin-5 [9]. Once in the cytoplasm, the pre-miRNAs undergo further processing by the ribonuclease Dicer, resulting in the formation of a miRNA duplex. Among these duplexes, a mature single-stranded miRNA is selectively incorporated into Argonaute (AGO) proteins within the RNA-induced silencing complex (RISC). This interaction culminates in the assembly of a functional miRNA-induced silencing complex (miRISC), which serves to modulate sequence-specific target genes [10]. This intricate regulatory mechanism underscores the pivotal role of miRNAs in post-transcriptional gene regulation and cellular homeostasis.

The mechanism of action of miRNAs exhibits notable divergence between plants and animals [11]. In plants, miRNAs typically engage in base-pairing interactions with messenger RNAs (mRNAs) that display perfect or near-perfect complementarity. This interaction facilitates the cleavage and subsequent degradation of target mRNAs through a mechanism known as RNA interference (RNAi). In mammals, most miRNAs do not exhibit complete complementarity to their mRNA targets. Instead, they predominantly exert their regulatory effects by repressing translation and inducing mRNA degradation. However, the precise mechanism underlying miRNA-mediated translational repression remains a subject of debate and controversy [12, 13]. miRNAs primarily recognize specific binding sites within the 3′-untranslated region (UTR) of their target mRNAs. They can also interact with the 5′-UTR, and intriguingly, may even upregulate translation under certain growth inhibitory conditions [14,15,16]. Due to the diverse rules governing the interaction between miRNAs and their target mRNAs, individual miRNAs have the capacity to regulate multiple target genes [17, 18]. Conversely, distinct miRNAs may also converge on regulating a specific gene, adding another layer of complexity to miRNA-mediated gene regulation [11]. This intricate network of miRNA-target interactions underscores the multifaceted role of miRNAs in modulating gene expression and cellular processes in both plants and animals (Fig. 1).

Fig. 1
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The mechanism of action of miRNAs

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2.1 The expression of miRNAs in PCa

The expression of miRNAs in prostate PCa plays a crucial role in mediating sequence-specific target genes, thereby influencing the disease's biological processes [19]. It is postulated that the oncogenic or tumor-suppressive effects of miRNAs in cancer are contingent upon their target genes. In PCa, numerous miRNAs exhibit dysregulated expression patterns and are categorized as either tumor suppressor miRNAs or oncogenic miRNAs based on their functional characteristics. These dysregulated miRNAs are implicated in various biological processes relevant to PCa, including cell proliferation, invasion, apoptosis, differentiation, and angiogenesis [20, 21]. The interplay between aberrantly expressed miRNAs and their target genes underscores the intricate molecular mechanisms underlying PCa pathogenesis and progression. Dysregulated miRNAs serve as key regulators of gene expression networks, exerting profound effects on cellular phenotypes and contributing to the complex landscape of PCa biology. Understanding the functional implications of dysregulated miRNAs in PCa holds promise for elucidating novel therapeutic targets and biomarkers, ultimately advancing precision medicine approaches for the diagnosis and treatment of this disease.

Oncogenes play a pivotal role in the development and progression of tumors by promoting abnormal cell growth and proliferation. Among these oncogenes, those exerting their effects by targeting and inhibiting tumor suppressor genes (TSGs) and genes involved in cellular differentiation and apoptosis are termed oncogenic miRNAs (Table 1). TSGs, also known as antioncogenes, constitute a crucial class of genes in normal cells and are capable of inhibiting cell growth and counteracting potential oncogenic effects. These genes function to negatively regulate cell growth, proliferation, and differentiation. Conversely, tumor suppressor miRNAs exert their oncogenic effects by targeting oncogenes (Table 1).

Table 1 Oncogenic miRNAs and TSGs
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2.2 Application of miRNAs in PCa diagnosis

PSA remains a widely used noninvasive biomarker for detecting PCa. It is a serine protease that primarily exists in two different forms in the human body. After entering the bloodstream, most PSA quickly binds to protease inhibitors, forming complex PSA (cPSA). A smaller portion is inactivated by proteases and remains in a free state, known as free PSA (fPSA). The sum of these two forms is generally used to represent the total serum PSA (tPSA) level. PSA is highly specific to prostate tissue but not specific to cancer. Therefore, men with benign prostate conditions, such as prostatitis or benign prostatic hyperplasia (BPH), often exhibit elevated serum PSA levels as well [47]. A meta-analysis [48] incorporating 11 RCTs with a total of 416,000 participants found that PSA screening in patients with PCa did not demonstrate remarkable benefits and may even lead to overdiagnosis. This overdiagnosis can result in treatment for PCa that leads to adverse events such as urinary incontinence and erectile dysfunction. Additionally, the false positive result associated with PSA testing often necessitates further procedures like biopsies, which also carry significant risks of complications. Consequently, the accuracy of using PSA levels as a criterion for PCa screening is compromised. Although multiparametric magnetic resonance imaging (mpMRI) is increasingly employed for localizing and stratifying prostate lesions, its high cost and inability to detect approximately 10% of major tumors necessitate the possibility of performing a second biopsy [49, 50].

Numerous investigations have underscored the involvement of dysregulated miRNAs in the progression of cancer. For instance, oligonucleotide array-based hybridization and clustering analyses conducted by Porkka et al. revealed differential expression patterns of miRNAs in both prostate hyperplasia and cancerous tissues, with a notable predominance of downregulated miRNAs in cancer samples compared to upregulated ones [51]. This overall downregulation of miRNAs in cancer cells is indicative of the poor differentiation of tumor cells relative to normal cells [52]. Furthermore, Roa et al. conducted RT-PCR tests on a PCa cell line, which demonstrated the overexpression of miR-20, miR-21, miR-99a, miR-141, miR-182, miR-198, and let-7a, juxtaposed with the downregulation of miR-145 and miR-155 [53]. In the study by Avgeris et al., a significant correlation was identified linking reduced expression of miR-145 with various prognostic factors in PCa, including Gleason score (GS), clinical stage, tumor size, PSA level, and follow-up PSA levels. This decrease in miR-145 expression was also strongly associated with an increased risk of biochemical recurrence and a reduction in disease-free survival among PCa patients. These findings emphasize the potential of miR-145 as a biomarker for assessing disease severity and progression in PCa, suggesting that monitoring its levels could offer valuable insights into patient prognosis and treatment outcomes [54].

Research has been actively pursuing blood-based diagnostics for monitoring PCa progression and recurrence through the differential expression of serum/plasma miRNAs. In an insightful study, the miRNA levels were analyzed in both cancerous and non-malignant tissues, as well as in serum samples from PCa patients before and after prostatectomy, documenting a significant reduction in the levels of miR-16, miR-26a, miR-195, and miR-32 in PCa tissues post-radical prostatectomy. This highlighted the potential of these tumor-associated miRNAs to facilitate noninvasive discrimination of PCa [55]. Further expanding on this area, a study employed a TRAMP model to identify novel circulating miRNAs that could serve as biomarkers for male PCa. Their research revealed that four miRNAs—miR-141, miR-298, miR-346, and miR-375—showed consistent changes in serum that correlated with those in male PCa patients [56]. Additionally, Cheng et al. identified a set of miRNAs (miR-141, miR-200a, miR-200c, miR-210, and miR-375) associated with metastatic castration-resistant PCa during the screening and validation phases of their study [57]. Based on the analysis of seven miRNAs in plasma samples, Mihelich et al. proposed the miR Risk Score, a scoring system designed to predict low-grade PCa with high accuracy [58].

Moreover, the similarity between miRNAs detected in urine and those expressed in prostate neoplasia has been investigated, suggesting their potential use as markers for PCa screening [59]. Bryzgunova et al. conducted a detailed analysis using a specific miRCURY LNA miRNA qPCR Panel to compare the expression of 84 miRNAs in samples enriched with extracellular vesicles and cell-free urine supernatants from healthy males, patients with benign prostatic hyperplasia, and PCa patients. This study identified five pairs of miRNAs that could be used to detect PCa and assist in therapy optimization [60].

Furthermore, semen has also been explored as a specimen for miRNA testing. Analysis showed elevated levels of pairs of five miRNAs (miR-200b, miR-200c, miR-30a, miR-375, and miR-99a) in patients with increased PSA and biopsy-confirmed cancer, with miR-200b notably showing a notable correlation with the GS, underscoring the potential of semen-based testing for diagnostic screening of PCa [61].

3 Application of miRNAs in the treatment of PCa with TCM

3.1 miRNAs and TCM syndrome differentiation

TCM syndrome differentiation is a method that encapsulates the pathological attributes of a disease at a specific stage of its progression, relying on the Four Diagnostic Methods: observation, auscultation and olfaction, inquiry, and pulse feeling/palpation. These traditional methods enable practitioners to assess the pathogenesis of diseases from a macroscopic perspective, adhering to the principle that internal imbalances are reflected externally. This approach to TCM embodies the dynamic evolution of a disease from cellular (microscopic) disruptions to the external symptoms (macroscopic) observed. In the realm of modern research, miRNAs have emerged as a significant area of study, particularly in how they relate to TCM deficiency syndromes through their roles in immune and metabolic regulation [62]. miRNAs have demonstrated potential as biomarkers for the classification and tracking of the evolutionary trends of TCM syndromes in various diseases. For instance, research has identified distinct miRNA profiles associated with TCM syndromes in conditions such as non-small cell lung cancer (NSCLC) [63] and aplastic anemia [64]. These findings offer a molecular foundation for understanding the various TCM syndromes present in these diseases. Additionally, disparities in serum miRNA expression levels among patients with different TCM syndromes across various diseases have prompted extensive studies. These studies aim to integrate macroscopic TCM syndrome differentiation with microscopic miRNA indicators, providing a scientific basis for elucidating TCM syndromes and addressing the limitations of traditional macroscopic methods of differentiation [65]. This holistic approach merges ancient diagnostic techniques with contemporary molecular science, enhancing the precision and understanding of TCM practices.

3.2 miRNAs and the physical constitution in TCM

In the context of modern medicine, a tumor is defined as a neoplasm that arises from the abnormal proliferation of local tissue cells due to various carcinogenic factors. TCM, however, interprets tumors through the lens of symptomatology, classifying them as “a lump,” “a mass,” or “a rock-like mass”. According to TCM theory, the pathogenesis of tumors primarily involves a combination of deficiency of Ben (root cause) and excess of Biao (manifested symptoms), such as kidney yang deficiency underpinning the condition, with qi stagnation, sputum retention, blood stasis, and accumulation of dampness manifesting as symptomatic expressions [66]. From the classical TCM text, “Su Wen” (Plain Questions), particularly in the section “Yin Yang Ying Xiang Da Lun” (Great Treatise on the Corresponding Manifestations of Yin and Yang), it is posited that the transformation of yang into qi and yin into material substance underlies the physiological processes. This text suggests that deficiencies in yang qi can lead to the condensation of cold, which is viewed as a fundamental cause of tumor development. This concept is further elaborated with the idea that “evil qi” invades primarily due to a deficiency in healthy qi, indicating that a lack of yang qi facilitates the invasion of cold, leading to fluid accumulation and blood stasis which together may foster the formation of tangible tumors. In a modern scientific context, a previous study explored these traditional concepts through contemporary biomedical research methodologies. Utilizing high-throughput sequencing technology, the study examined the relationship between physical constitution and exosomal miRNAs. It was discovered that 28 miRNAs exhibited altered expressions in a yang-deficient constitution compared to a moderate constitution. These miRNAs are implicated in causing diseases through cytokine signaling pathways among other mechanisms, thereby providing a molecular basis for understanding how traditional concepts of yang deficiency relate to disease pathogenesis, including tumor formation [67].

3.3 miRNAs and the mechanism of action of TCM

TCM possesses unique advantages such as minimal adverse reactions and synergistic effects in enhancing efficacy while reducing toxicity. The application of TCM in the treatment of PCa can mitigate the adverse effects associated with modern medical treatments. TCM also significantly contributes to immune regulation, prolonging survival, and improving the quality of life for patients [68]. The combination of the “syndrome differentiation and treatment” theory with the unique pharmacological advantages of TCM has shown significant efficacy in the treatment of PCa. The role of miRNAs in the development and progression of malignant tumors has become a research focus in recent years. miRNAs are involved in regulating tumor cell proliferation, apoptosis, and invasion/metastasis mechanisms, with different miRNAs exerting either oncogenic or tumor-suppressive effects in various malignancies [69]. Various studies have confirmed that TCM can exert anti-tumor effects by modulating the expression of PCa-related miRNAs (Table 2).

Table 2 miRNAs in the treatment of PCa with TCM
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The distinct active components of single TCM have demonstrated significant potential in the treatment of PCa. For example, curcumin, an active anti-tumor compound derived from Curcumae Longae Rhizoma (turmeric), has been shown to play a significant anti-tumor role by inhibiting the activation of β-catenin/c-Myc proteins and cell proliferation through the upregulation of miR-34a in PCa cells [70]. Curcumin can also curb PCa proliferation and invasion by enhancing the expression of tumor suppressor miR-145, which subsequently inhibits the expression of lncRNA-ROR and Oct4[71]. Curcumin can upregulate the expression of miR-199a-3p, thereby inhibiting the proliferation, migration, and invasion of prostate cancer C4-2 cells [72]. Curcumin also inhibits PC3 cell proliferation, promotes apoptosis, and reduces tumor weight in xenograft models of nude mice, with the underlying mechanism possibly involving the downregulation of miR-210 expression, which subsequently suppresses the TLR4 signaling pathway and decreases the expression of inflammatory cytokines [73]. In addition, it can inhibit the development and progression of PCa by targeting the LINC00491/miR-532-3p axis, which suppresses the expression of KI67, MMP-2, and MMP-9, and promotes the expression of Caspase 3 [74]. A recent study [75] indicated that curcumin inhibits PCa by upregulating miR-483-3p and inhibiting UBE2C. Astragalus polysaccharides (APS) is one of the main active components of the TCM Astragalus, and can inhibit the proliferation, invasion, and migration of DU145 cells by upregulating miR-133a [76]. Other findings suggested that APS inhibits tumorigenesis and lipid metabolism in PCa through miR-138-5p/SIRT1/SREBP1 pathways [77].

Moreover, compound preparations from TCM, known for their multi-target and multi-pathway therapeutic actions, hold significant potential in disease treatment. An example is the Guben Sanjie Formula, which includes ingredients such as Hedyotis diffusa, Lobelia chinensis, Salvia miltiorrhiza, Ficus hirta, Fritillaria thunbergii Miq., and Glycyrrhizae Radix et Rhizoma (licorice). This formula has been shown to modulate miRNA expression, specifically downregulating miR-188 and upregulating Caspase-3 & Bax, which are involved in the apoptotic pathway. This modulation leads to decreased expression of Ki-67 and Bcl-2, thereby supporting the treatment of PCa by replenishing qi, strengthening vital qi, promoting blood circulation, and dissipating masses [78]. Yishen Tonglong Decoction can promote apoptosis in prostate cancer PC-3 cells by upregulating the expression of miR-145-5p, which inhibits the TLR4/p38 MAPK/NF-κB signaling pathway [79]. Qilan Formulation may inhibit the proliferation of DU145 cells and promote apoptosis by downregulating the expression of miR-1297, increasing PTEN expression, and reducing PI3K/AKT phosphorylation, thereby regulating the expression of cell cycle and apoptosis-related factors (Cyclin D1, Bcl-2, Bax, Cleaved-caspase 3) in downstream pathways [80].

4 Other miRNA-based interventions for PCa

miRNAs possess the ability to bind to multiple targets and regulate various cancer-related gene networks, making them potent tools for developing new therapies aimed at targeting PCa. It was discovered that androgen ablation therapy is highly effective in treating advanced PCa, and miR-133a-5p has been identified as inhibiting the proliferation of androgen receptor (AR)-positive PCa cells by targeting the FUS/AR interaction, which enhances resistance to androgen ablation therapy [81]. Additionally, RNA interference technology has been shown to regulate the post-transcriptional expression of cancer genes and interfere with related protein expression, demonstrating significant anti-cancer effects [82]. However, miRNAs face significant challenges in efficiently penetrating tumor tissues and are prone to rapid degradation and elimination during blood circulation [83, 84]. To overcome these challenges, research into nanoparticle encapsulation of RNA has shown that nanoparticles often face endosomal/lysosomal disruption after cellular internalization. A study introduced a PMPC complex where the outer layer dissolves in low-pH environments, triggering the rapid release of the PMPC polymer from endosomes/lysosomes and enhancing the cytoplasmic delivery of miR146a. This method has proven effective in inhibiting the expression of the epidermal growth factor receptor (EGFR) in androgen-independent prostate cancer (AIPC) [85, 86]. Furthermore, radiotherapy, while a standard treatment for PCa, has associated adverse reactions that are a significant clinical concern. A recent study confirmed that a hypothetical treatment involving miR-1272 recombination combined with ionizing radiation could improve the response of PCa to conventional radiotherapy, suggesting a promising direction for enhancing treatment efficacy while mitigating side effects [87].

5 miRNAs and PCa prognosis

While the GS is the premier prognostic indicator in PCa management, several challenges compromise its reliability. These include the fact that only 2% of prostate tumor samples can be obtained by puncture [88], discrepancies between GS in aspiration biopsy and prostatectomy specimens [89], and the variability in the clinical judgment of observers as well as sampling errors [90,91,92]. Furthermore, the stability and specific roles of miRNAs in cancer have generated considerable interest in their potential for PCa prognosis.

It has been observed that nearly 30% of PCa patients undergoing radical prostatectomy (RP) experience clinical recurrence, marked by increased PSA levels [93]. The search for reliable predictors of PCa recurrence is therefore critical. Molecular changes in miRNAs have been linked to the initiation and progression of PCa [94]. A meta-analysis of five studies, comprising six miRNA datasets, indicated that in recurrent PCa samples, miRNAs such as miR-125A, miR-199A-3P, miR-28-5P, miR-301B, miR-324-5B, miR-361-5P, miR-363, miR-449A, miR-484, miR-498, miR-579, miR-637, miR-720, miR-874, and miR-98 were typically upregulated, while miR-639, miR-661, miR-760, miR-890, and miR-939 were usually downregulated, marking them as candidate predictive markers of recurrent PCa after RP [95]. Furthermore, genome-wide miRNA expression profiling of PCa tissue samples from 123 men who received RP showed a correlation between poor prognosis after RP and relatively high expression of miR-10b-5p/miR-23a-3p or relatively low expression of miR-133a/miR-374b-5p. The four-miRNA prognostic ratio model, MiCaP (miR-23a-3p × miR-10b-5p)/(miR-133a × miR-374b-5p), was identified as a prognostic marker for predicting postoperative biochemical recurrence (BCR) and prostate cancer-specific survival (CSS) [96].

Additionally, the role of plasma exosomal miRNAs in predicting the prognosis of castration-resistant prostate cancer (CRPC) was evaluated in a screening cohort of 23 cases. RNA sequencing was used to identify candidate exosomal miRNAs associated with overall survival (OS), and Cox regression analysis identified miR-1290, miR-1246, and miR-375 as significant. In these populations, higher miR-1290 and miR-375 levels were significantly associated with lower overall survival. Further clinical prognostic assessment in 100 patients using real-time qPCR showed that the time-dependent area under the curve (AUC) improved from 0.66 to 0.73, significantly enhancing predictive performance [97].

6 Conclusion and Outlook

Addressing the challenge of performing predictive examinations at the early stages of cancer development and intervening in the treatment process is crucial in modern medicine. Although PSA is commonly used for screening in clinical practice, it lacks sufficient specificity, underscoring the urgent need to identify effective biological markers for clinical application. PCa typically progresses slowly and is not detectable in its early stages by conventional instrumental analytical methods such as X-ray scanning, MRI, and ultrasonography. The clonal and heterogeneous nature of cancer also means its phenotype cannot always be comprehensively characterized by biopsy.

Tumor-derived miRNAs, detectable in the extracellular space (ECS) and various biological fluids, offer a promising avenue for non-invasive cancer diagnostics and phenotyping through liquid biopsies98. Additionally, there has been progress in the application of miRNAs in the treatment of PCa using TCM. Future efforts should focus on further analyzing the gene expression profiles of miRNAs in different types of PCa compared to normal control populations, screening for differential genes associated with each syndrome of PCa, and exploring the nature of each syndrome of PCa and the underlying pathological mechanisms at the genetic level. As research on the mechanism of miRNA action in tumor biology deepens, and with the advancement of high-throughput technologies such as miRNA microarrays, new methods for treating PCa have emerged. In conclusion, miRNAs play a significant role in the occurrence, development, diagnosis, treatment, and prognosis of PCa, and they may become a new target for PCa intervention.