**1. Introduction**

Cancer is the most common cause of death, with a high mortality rate worldwide causing 10 million fatalities per year. Cancer is characterized by unregulated cell growth and rapid proliferation [1]. Uncontrolled cell proliferation, aggregation, and an aberrant cell cycle are hallmarks of human cancer. Typically, cell division is controlled by several regulatory factors, including protein kinases [2]. Among all known protein kinases, NIMA (never in mitosis, gene A) related kinase7 (NEK7) plays a multifunctional role [3], including centrosome duplication, intracellular protein transport, mitotic spindle assembly, DNA repair, and cytokinesis [4–7].

NEK7 is a highly conserved serine/threonine kinase consisting of approximately 302 amino acids [6]. NEK7 is structurally related to NEK6, which shares 85% amino acid sequence identity. However, NEK7 is involved in critical roles that NEK6 cannot take over. NEK7 is centrosome-localized and is known to be highly expressed in a variety of vital organs such as the heart, lung, fat, brain, liver, and spleen [8]. It enhances the centrosome duplication efficiency by promoting the pericentriolar material at the centrosome during the S and G1 phases [3].

In addition, NEK7 also encourages the proliferation of resting cells, which indicates its high-level involvement in various cancer types, including non-small lung cancer, breast cancer, NLRP3-related inflammatory disease, and gastric cancer progression [9]. NEK7 also has a promising role in growth and survival. NEK9 regulates the activation of NEK7 during mitosis, which promotes spindle assembly, centrosome separation, and mitotic division of the cell [7].

Besides promoting the proliferation of various resting cells, NEK7 is also involved in the progression and development of fatal inflammatory diseases, including Alzheimer's disease, auto-immune disorders, inflammatory bowel disease, gout, and tumor formation [10]. Researchers have reported the involvement of NEK7 in the activation of NLRP3 inflammasome via ROS species formation, lysosomal destabilization, and potassium efflux. Stimulation of inflammatory mediators by NEK7 induces fibrosis and diabetic retinopathy and leads to hepatic carcinoma [10]. In brief, any mutation or atypical expression of NEK7 leads to the development of cellular oncogenesis and may provoke a fatal inflammatory response, causing tumorigenesis of multiple organs. These findings lend testimony to the involvement of NEK7 in the progression and development of numerous deadly diseases.

NEK7 is a promising target for multiple diseases, primarily cancer-related therapy research. NEK7 came into consideration two decades ago [2], but it has yet to be explored as a therapeutic target for preventing and treating NEK7-related diseases. A few medications have recently been developed to target the NEK7-mediated inflammasome pathway, but the mechanism and treatment outcomes are not specific and consistent [2].

Moreover, there is no FDA-approved medication that can selectively inhibit the expression of NEK7. Only Dabrafenib has shown activity against BRAF-mutant melanoma, which expresses more NEK9 [1]. These findings indicate that no published work has reported the selective and potent inhibitors of NEK7. As a result, the current study seeks more specific inhibitors that will provide a beneficial treatment option for NEK7-related cancer malignancies.

The current study focused on structure-based virtual screening (SBVS) of 1200 compounds library and drug repurposing of FDA-approved drug Dabrafenib. Dabrafenib demonstrated inhibitory potential against NEK9 with an IC50 value ranging from 1–9 nM [11,12]. Dabrafenib is comprised of benzene sulphonamide scaffolds. The basic sulphonamide group occurs in numerous biological active compounds [12], including anti-microbial [13], anti-tumor [14], anti-thyroid [15], antibiotics [16], and carbonic anhydrase inhibitors [17].

Clinically, sulphonamide-possessing drugs are used to treat lower urinary tract infections, whereas aromatic or hetero-aromatic sulphonamide derivatives possess a wide range of biological activities, including anti-tumor, anti-rheumatic, anti-microbial, and anti-inflammatory [18–21]. These findings have provided a strong rationale to retrieve structural analogues of Dabrafenib containing a basic sulphonamide nucleus.

The library of 1200 structural analogues of Dabrafenib was retrieved from the Pub-Chem database and subjected to the in-silico drug discovery process. The discovery of a new anti-cancer agent is an extensive and laborious process. Thus, computer-aided drug design (CADD) [22] methods could serve as an alternative drug development strategy [23]. Among in-silico approaches, drug repurposing is an advanced tool for revisiting the activities of already approved drugs [24], which can save time and money [25].

The current study was focused to revisit the activity of Dabrafenib against NEK7 protein [26]. In addition, structure-based virtual screening (SBVS) [26] of 1200 structural analogues of Dabrafenib was carried out using molecular docking [27] and deep learning models [28]. SBVS is an advanced technology for the identification of potential hits with significant pharmacological properties against multiple molecular targets. Several robust docking programs are available for docking purposes in commercial and academic settings. In the present study, the Auto Dock Vina was used for virtual screening [29,30]. Moreover, density functional theory studies were conducted to explore the chemical reactivity profile of top-ranked analogues obtained through virtual screening. The structural geometry optimization and frequency calculations were performed. In addition, frontier molecular orbital (FMO) analysis and global reactivity descriptors were also determined. The efficacy of any drug is determined by its interaction with targeted biomolecules. Deep learning algorithms [31] were used for prediction of binding affinity and pIC<sup>50</sup> values of top hits obtained via virtual screening. Predicted values of top hits were compared to in-vitro activity of Dabrafenib.

Furthermore, in-silico ADMET properties were also determined using a messagepassing neural network (MPNN). The MPNN model is widely used for prediction of molecular properties such as blood brain barriers, human intestinal absorption, and solubility profiles [32]. The molecular docking approach only provides a static view of the molecular interactions of the complex. Still, to determine the stability of the protein–ligand complex, molecular dynamic simulations (MD simulations) have been performed to determine the stability, which provide significant insight into the molecular interactions of top-ranked complexes under accelerated conditions. Top hits obtained through structure based virtual screening a shown in Figure 1. All hits shared the same pharmacophore with standard Dabrafenib.

This is the first comprehensive computational study for the identification of selective inhibitors of the NEK7 protein. The current study has utilized the latest computational approaches, suggesting identified hits as a new strategy for treatment of NEK7-associated malignancies. Findings of the current study suggest the exploration of the inhibiting potential of these hits at the molecular level using in-vitro and in-vivo experimental techniques.

**Figure 1.** Top Hits obtained through SBVS. All hits were sharing same basic Pharmacophore with standard Dabrafenib.
