MicroRNAs as Potential Predictors of Response to CDK4/6 Inhibitor Treatment

MicroRNA-based interventions in aberrant cell cycle diseases: Therapeutic strategies for cancers, central nervous system disorders and comorbidities

Malignant tumors and central nervous system (CNS) disorders are intricately linked to a process known as "aberrant cell cycle re-entry," which plays a critical role in the progression of these diseases. Addressing the dysregulation in cell cycles offers a promising therapeutic approach for cancers and CNS disorders. MicroRNAs (miRNAs) play a crucial role as regulators of gene expression in cell cycle transitions, presenting a promising therapeutic avenue for treating these disorders and their comorbidities. This review consolidates the progress made in the last three years regarding miRNA-based treatments for diseases associated with aberrant cell cycle re-entry. It encompasses exploring fundamental mechanisms and signaling pathways influenced by miRNAs in cancers and CNS disorders, particularly focusing on the therapeutic effects of exosome-derived miRNAs. The review also identifies specific miRNAs implicated in comorbidity of cancers and CNS disorders, discusses the future potential of miRNA reagents in managing cell cycle-related diseases.

Cyclin-Dependent Kinase 4/6 Inhibitors as Neoadjuvant Therapy of Hormone Receptor-Positive/HER2-Negative Early Breast Cancer: What do we Know so Far?

The introduction of cyclin-dependent kinase 4/6 (CDK4/6) inhibitors to the treatment of hormone receptor-positive and human epidermal growth factor receptor 2-negative (HR+/HER2-) metastatic breast cancer is regarded as one of the greatest achievements of the last decades in breast oncology. To date, palbociclib, abemaciclib and ribociclib are the 3 approved CDK4/6 inhibitors that combined with endocrine therapy are now considered as the standard first-line treatment of metastatic HR+/HER2- breast cancer. The great success of these drugs in the setting of metastatic disease and the need to combat the high risk of recurrence have paved the way for a number of clinical trials to explore the use of CDK4/6 inhibitors in the neoadjuvant treatment of early breast cancer. In this review, we summarize the main findings of clinical trials that examined the use of CDK4/6 inhibitors in combination with hormone therapy or chemotherapy as neoadjuvant treatment of hormone receptor-positive and HER2-negative breast cancer. Active clinical trials that investigate different treatment schemes are also briefly presented and current limitations and future goals are discussed.

Liquid biopsy utilizing miRNA in patients with advanced breast cancer treated with cyclin‑dependent kinase 4/6 inhibitors

Cyclin-dependent kinase 4/6 inhibitors (CDK4/6is) are the mainstay of treatment of hormone receptor+/human epidermal growth factor receptor 2-patients with advanced breast cancer (ABC). Despite improvements in overall survival, most patients experience disease progression. Biomarkers derived from a liquid biopsy are appealing for their potential to detect resistance to treatment earlier than computed tomography imaging. However, clinical data concerning microRNAs (miRNAs/miRs) in the context of CDK4/6is are lacking. Thus, the present study assessed the use of miRNAs in patients with ABC treated with CDK4/6is. Patients treated for ABC with CDK4/6is between June and August 2022 were eligible. miRNA expression analyses were performed using a TaqMan™ low-density miRNA array. A total of 80 consecutive patients with ABC treated with CDK4/6is at Maria Sklodowska-Curie National Research Institute of Oncology (Gliwice, Poland) were assessed, with 14 patients diagnosed with progressive disease at the time of sampling, 55 patients exhibited clinical benefit from CDK4/6i treatment and 11 patients were at the beginning of CDK4/6i treatment. Patients with disease progression had significantly higher levels of miR-21 (P=0.027), miR-34a (P=0.011), miR-193b (P=0.032), miR-200a (P=0.027) and miR-200b (P=0.003) compared with patients who benefitted from CDK4/6i treatment. Significantly higher levels of miR-34a expression were observed in patients with progressive disease than in patients beginning treatment (P=0.031). The present study demonstrated the potential innovative role of circulating miRNAs during CDK4/6i treatment. Plasma-based expression of miR-21, -34a, -193b, -200a and -200b effectively distinguished patients with ABC who responded to CDK4/6i treatment from patients who were resistant. However, longitudinal studies are required to verify the predictive and prognostic potential of miRNA.

Identification of a Panel of miRNAs Associated with Resistance to Palbociclib and Endocrine Therapy

We investigated whether we could identify a panel of miRNAs associated with response to treatment in tumor tissues of patients with Hormone Receptor-positive/HER2-negative metastatic breast cancer treated with endocrine therapy (ET) and the CDK4/6 inhibitor (CDK4/6i)i palbociclib. In total, 52 patients were evaluated, with 41 receiving treatment as the first line. The overall median PFS was 20.8 months (range 2.5-66.6). In total, 23% of patients experienced early progression (<6 months). Seven miRNAs (miR-378e, miR-1233, miR-99b-5p, miR-1260b, miR-448, -miR-1252-5p, miR-324-3p, miR-1233-3p) showed a statistically significant negative association with PFS. When we considered PFS < 6 months, miR-378e, miR-99b-5p, miR-877-5p, miR-1297, miR-455-5p, and miR-4536-5p were statistically associated with a poor outcome. In the multivariate analysis, the first three miRNAs confirmed a significant and independent impact on PFS. The literature data and bioinformatic tools provide an underlying molecular rationale for most of these miRNAs, mainly involving the PI3K/AKT/mTOR pathway and cell-cycle machinery as cyclin D1, CDKN1B, and protein p27Kip1 and autophagy. Our findings propose a novel panel of miRNAs associated with a higher likelihood of early progression in patients treated with ET and Palbociclib and may contribute to shed some light on the mechanisms of de novo resistance to CDK4/6i, but this should be considered exploratory and evaluated in larger cohorts.

Regulation of the Cell Cycle by ncRNAs Affects the Efficiency of CDK4/6 Inhibition

Cyclin-dependent kinases (CDKs) regulate cell division at multiple levels. Aberrant proliferation induced by abnormal cell cycle is a hallmark of cancer. Over the past few decades, several drugs that inhibit CDK activity have been created to stop the development of cancer cells. The third generation of selective CDK4/6 inhibition has proceeded into clinical trials for a range of cancers and is quickly becoming the backbone of contemporary cancer therapy. Non-coding RNAs, or ncRNAs, do not encode proteins. Many studies have demonstrated the involvement of ncRNAs in the regulation of the cell cycle and their abnormal expression in cancer. By interacting with important cell cycle regulators, preclinical studies have demonstrated that ncRNAs may decrease or increase the treatment outcome of CDK4/6 inhibition. As a result, cell cycle-associated ncRNAs may act as predictors of CDK4/6 inhibition efficacy and perhaps present novel candidates for tumor therapy and diagnosis.

Biomarkers of Response and Resistance to CDK4/6 Inhibitors in Breast Cancer: Hints from Liquid Biopsy and microRNA Exploration

New evidence on the impact of dysregulation of the CDK4/6 pathway on breast cancer (BC) cell proliferation has led to the development of selective CDK4/6 inhibitors, which have radically changed the management of advanced BC. Despite the improved outcomes obtained by CDK4/6 inhibitors, approximately 10% of tumors show primary resistance, whereas acquired resistance appears to be an almost ubiquitous occurrence, leading to treatment failure. The identification of differentially expressed genes or genomic mutational signatures able to predict sensitivity or resistance to CDK4/6 inhibitors is critical for medical decision making and for avoiding or counteracting primary or acquired resistance against CDK4/6 inhibitors. In this review, we summarize the main mechanisms of resistance to CDK4/6 inhibitors, focusing on those associated with potentially relevant biomarkers that could predict patients' response/resistance to treatment. Recent advances in biomarker identification are discussed, including the potential use of liquid biopsy for BC management and the role of multiple microRNAs as molecular predictors of cancer cell sensitivity and resistance to CDK4/6 inhibitors.

Mir-29b in Breast Cancer: A Promising Target for Therapeutic Approaches

The miR-29 family comprises miR-29a, miR-29b, and miR-29c, and these molecules play crucial and partially overlapped functions in solid tumors, in which the different isoforms are variously de-regulated and mainly correlated with tumor suppression. miR-29b is the most expressed family member in cancer, in which it is involved in regulating gene expression at both transcriptional and post-transcriptional levels. This review focuses on the role of miR-29b in breast cancer, in which it plays a controversial role as tumor suppressor or onco-miRNA. Here we have highlighted the dual effect of miR-29b on breast tumor features, which depend on the prevailing function of this miRNA, on the mature miR-29b evaluated, and on the breast tumor characteristics. Remarkably, the analyzed miR-29b form emerged as a crucial element in the results obtained by various research groups, as the most abundant miR-29b-3p and the less expressed miR-29b1-5p seem to play distinct roles in breast tumors with different phenotypes. Of particular interest are the data showing that miR-29b1-5p counteracts cell proliferation and migration and reduces stemness in breast tumor cells with a triple negative phenotype. Even if further studies are required to define exactly the role of each miR-29b, our review highlights its possible implication in phenotype-specific management of breast tumors.

MiR-4284 inhibits sensitivity to paclitaxel in human ovarian carcinoma SKOV3ip1 and HeyA8 cells by targeting DMC1

An increasing number of studies have confirmed that microRNAs (miRNAs) are involved in various biological processes, including tumor growth and drug resistance. MiR-4284 has been proved to be abnormally regulated in several cancers, but the function of miR-4284 in ovarian carcinoma (OC) is unclear. Paclitaxel resistance is a key obstacle in OC treatment. Here, the role of miR-4284 in cell sensitivity to paclitaxel in OC was investigated. Two OC cell lines (SKOV3ip1 and HeyA8) were utilized for the establishment of paclitaxel-resistant cell lines. Reverse transcription-quantitative PCR (RT-qPCR) was applied to analyze the levels of miR-4284 and potential mRNAs in OC cell lines. Western blotting was performed to evaluate the levels of DNA meiotic recombinase 1 (DMC1) protein and cell cycle-associated proteins. Identification of the relationship between miR-4284 and DMC1 was achieved by luciferase reporter assay. CCK-8 and flow cytometry assays were utilized for evaluating the impact of miR-4284 on the malignant characteristics of paclitaxel-resistant OC cells. MiR-4284 was upregulated in paclitaxel-resistant OC cell lines and correlated with an adverse prognosis in OC patients. Depletion of miR-4284 suppressed cell proliferation and cell cycle progression of paclitaxel-resistant OC. MiR-4284 targeted DMC1 which was downregulated in paclitaxel-resistant cells and reversed the inhibitory influence of miR-4284 silencing on the malignant characters of paclitaxel-resistant OC cells. MiR-4284 targets DMC1 to suppress sensitivity to paclitaxel in human OC cells.

The Role of CDK Pathway Dysregulation and Its Therapeutic Potential in Soft Tissue Sarcoma

Soft tissue sarcomas (STSs) are tumors that are challenging to treat due to their pathologic and molecular heterogeneity and their tumor biology that is not yet fully understood. Recent research indicates that dysregulation of cyclin-dependent kinase (CDK) signaling pathways can be a strong driver of sarcogenesis. CDKs are enzyme forms that play a crucial role in cell-cycle control and transcription. They belong to the protein kinases group and to the serine/threonine kinases subgroup. Recently identified CDK/cyclin complexes and established CDK/cyclin complexes that regulate the cell cycle are involved in the regulation of gene expression through phosphorylation of critical components of transcription and pre-mRNA processing mechanisms. The current and continually growing body of data shows that CDKs play a decisive role in tumor development and are involved in the proliferation and growth of sarcoma cells. Since the abnormal expression or activation of large numbers of CDKs is considered to be characteristic of cancer development and progression, dysregulation of the CDK signaling pathways occurs in many subtypes of STSs. This review discusses how reversal and regulation can be achieved with new therapeutics and summarizes the current evidence from studies regarding CDK modulation for STS treatment.

CDK4/6 inhibitors: mechanisms of resistance and potential biomarkers of responsiveness in breast cancer

Hormone receptor (HR)-positive, HER2-negative tumors represent the most common form of metastatic breast cancer (MBC), and endocrine therapy has been the mainstay treatment for several decades. Recently, a novel drug class called CDK4/6 inhibitors in combination with endocrine therapy have remarkably improved the outcome of patients with HR-positive, HER2-negative MBC by targeting the cell cycle machinery and overcoming aspects of endocrine resistance. Several potential cell-cycle-specific and nonspecific mechanisms of resistance to CDK4/6 inhibitors have been reported in recent studies. This review discusses potential resistance mechanisms to CDK4/6 inhibitors, the use of biomarkers to guide treatment for HR-positive, HER2-negative MBC and possible approaches to overcome resistance to CDK4/6 inhibitors.

Advances in the Application of Exosomes Identification Using Surface-Enhanced Raman Spectroscopy for the Early Detection of Cancers

Exosomes are small nanoscale vesicles with a double-layered lipid membrane structure secreted by cells, and almost all types of cells can secrete exosomes. Exosomes carry a variety of biologically active contents such as nucleic acids and proteins, and play an important role not only in intercellular information exchange and signal transduction, but also in various pathophysiological processes in the human body. Surface-enhanced Raman Spectroscopy (SERS) uses light to interact with nanostructured materials such as gold and silver to produce a strong surface plasmon resonance effect, which can significantly enhance the Raman signal of molecules adsorbed on the surface of nanostructures to obtain a rich fingerprint of the sample itself or Raman probe molecules with ultra-sensitivity. The unique advantages of SERS, such as non-invasive and high sensitivity, good selectivity, fast analysis speed, and low water interference, make it a promising technology for life science and clinical testing applications. In this paper, we briefly introduce exosomes and the current main detection methods. We also describe the basic principles of SERS and the progress of the application of unlabeled and labeled SERS in exosome detection. This paper also summarizes the value of SERS-based exosome assays for early tumor diagnosis.