GSK923295 as a Potential Antihepatocellular Carcinoma Agent Causing Delay on Liver Regeneration After Partial Hepatectomy
Hepatocellular carcinoma (HCC) remains a leading cause of cancer-related mortality worldwide, with surgical resection serving as the primary treatment for resectable cases. However, postoperative challenges such as rapid tumor recurrence and insufficient liver regeneration underscore the need for adjuvant therapies that balance antitumor efficacy with preservation of hepatic regenerative capacity. GSK923295, a selective inhibitor of centromere-associated protein E (CENP-E), has emerged as a promising antimitotic agent with potential advantages over traditional microtubule-targeting chemotherapeutics, particularly in minimizing neurotoxicity. This study comprehensively evaluates the dual effects of GSK923295 on HCC suppression and liver regeneration post-partial hepatectomy (PH), providing critical insights into its therapeutic applicability.
Anticancer Activity of GSK923295 in HCC Models
GSK923295 exhibited potent antiproliferative effects across multiple HCC cell lines (HepG2, MHCC-LM3, and HUH7), with half-maximal inhibitory concentrations (IC50) of 7.5 µM, 5.9 µM, and 2.9 µM, respectively, after 96 hours of exposure (Figure 1A). The variability in sensitivity among cell lines suggested factors beyond proliferation rate influence drug response. Cell cycle analysis revealed G2/M-phase arrest, characterized by elevated levels of mitotic markers cyclin B1 and phosphorylated histone H3 (pHH3) (Figure 1B). Prolonged exposure (48–96 hours) triggered apoptosis, evidenced by poly-(ADP-ribose) polymerase (PARP) cleavage.
In vivo validation using subcutaneous xenografts of MHCC-LM3 cells demonstrated delayed tumor growth upon intraperitoneal administration of 125 mg/kg GSK923295, though complete regression was not observed (Figure 1C–D). Tumor volume reduction correlated with increased mitotic figures, confirming mitotic arrest as the primary mechanism (Figure 1E). A patient-derived tumor xenograft (PDTX) model further substantiated these findings, albeit with attenuated efficacy, likely due to complexities in the tumor microenvironment (Figure 1F–G).
Mechanistic Insights into GSK923295-Induced Mitotic Arrest
GSK923295 disrupts chromosome alignment by inhibiting CENP-E, a kinetochore-associated motor protein essential for metaphase plate formation. In AML12 hepatocytes, treatment with 5 µM GSK923295 induced prolonged mitotic arrest (41.23% vs. 62.05% of cells in G2/M phase at 8 hours compared to controls), followed by apoptotic cell death at 48–96 hours (Figure 2A–E). Immunofluorescence imaging revealed misaligned chromosomes near spindle poles or scattered across the metaphase plate (Figure 2F), phenotypes recapitulated by CENP-E siRNA knockdown (Figure 2G–I). These results underscore CENP-E’s critical role in mitotic fidelity and validate GSK923295’s mechanism of action.
Impact of GSK923295 on Liver Regeneration Post-PH
Partial hepatectomy (70% liver resection) in C57BL/6 mice induced robust hepatic regeneration, peaking at 72 hours. Microarray analysis identified dynamic upregulation of CENP-E mRNA (41.3-fold increase at 48 hours post-PH) and protein, paralleling regenerative hyperplasia (Figure 3B–E). GSK923295 administration significantly impaired regeneration, reducing the liver-to-body weight ratio (L/BW) from 3.509% ± 0.129% (vehicle) to 2.888% ± 0.251% at 72 hours (Figure 4A). Immunohistochemical staining for proliferation markers Ki-67 and proliferating cell nuclear antigen (PCNA) confirmed diminished hepatocyte proliferation in treated mice (Figure 4B–F), while albumin expression remained unaffected, indicating preserved hepatic function (Figure 4G).
Notably, pHH3 levels surged transiently at 24 hours post-treatment, reflecting mitotic arrest, before declining as cells exited mitosis or underwent apoptosis (Figure 4H). The delayed regeneration coincided with suppressed BubR1 kinase expression, a CENP-E interactor critical for mitotic checkpoint signaling (Figure 4I–J). The strong correlation between CENP-E and BubR1 mRNA levels (linear coefficients: 0.7057 for vehicle, 0.6678 for GSK923295) suggested interdependent roles in coordinating hepatocyte division during regeneration.
Therapeutic Implications and Safety Considerations
GSK923295’s antitumor efficacy in HCC models aligns with its antimitotic mechanism, though the absence of complete tumor regression highlights potential limitations in monotherapy. The compound’s comparable inhibition of HCC cells and regenerating hepatocytes raises concerns about post-resection liver recovery. However, the temporal dissociation between peak CENP-E expression (48 hours post-PH) and maximal regenerative activity (72 hours) suggests a window for timed drug administration to minimize hepatic toxicity.
The study further identifies pHH3 as a potential pharmacodynamic biomarker for GSK923295 activity, given its correlation with mitotic arrest and subsequent apoptosis. Clinical translation will require optimizing dosing schedules to exploit differential proliferation rates between tumors and regenerating liver tissue, thereby enhancing therapeutic specificity.
Conclusion
GSK923295 demonstrates significant antineoplastic activity against HCC by inducing mitotic arrest and apoptosis, validated across cell lines, xenografts, and PDTX models. However, its potent inhibition of CENP-E also delays liver regeneration post-PH, necessitating careful consideration of treatment timing and monitoring of hepatic function. These findings position GSK923295 as a promising yet dual-edged therapeutic candidate, warranting further investigation into strategies to balance its antitumor efficacy with regenerative safety.
doi.org/10.1097/CM9.0000000000000053
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