Motor Protein KIFC1 Fuels Cervical Cancer Radioresistance Through a Splicing-Driven Glycolytic Switch

Cervical cancer remains one of the most formidable challenges in oncology, claiming hundreds of thousands of lives worldwide each year despite decades of progress in screening, surgery and chemoradiation. For patients with locally advanced disease, radiotherapy is a cornerstone of treatment, yet its effectiveness is frequently undermined by the emergence of radioresistance, a phenomenon in which tumour cells acquire the ability to survive otherwise lethal doses of ionising radiation. A new study published in the Journal of Cellular and Molecular Medicine has now uncovered a previously hidden molecular circuit that connects intracellular transport, RNA splicing and cellular metabolism to this treatment failure, and in doing so has identified a promising target that could make cervical tumours far more vulnerable to radiation.

The research, led by investigators at Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, centres on kinesin family member C1, or KIFC1, a motor protein best known for hauling cargo along microtubules and for its role in centrosome clustering during cell division. By mining six publicly available transcriptomic datasets of cervical cancer, the team found that KIFC1 was among the most significantly dysregulated kinesin genes in tumour tissue compared with healthy cervical tissue. Pan-cancer analysis across more than twenty tumour types confirmed widespread overexpression, and examination of clinical databases linked elevated KIFC1 to lymph node metastasis. Crucially, the findings were not confined to computational correlations: immunohistochemical staining of a tissue microarray containing 115 cervical carcinoma specimens and 39 adjacent non-tumour tissues showed markedly higher KIFC1 protein levels in tumours, and patients whose tumours expressed high levels of the protein experienced significantly poorer disease-free and overall survival.

To probe what KIFC1 actually does inside cervical cancer cells, the researchers engineered HeLa and SiHa cell lines with stable KIFC1 knockdown or overexpression using lentiviral vectors. The functional consequences were striking. Depleting KIFC1 curtailed cell proliferation in cell counting and colony formation assays and impaired migration in wound healing and Transwell experiments, while forcing KIFC1 expression produced the opposite effects, enhancing growth and motility. But the most revealing clue came from RNA sequencing of KIFC1-silenced cells, which identified 2,714 differentially expressed genes. Pathway enrichment analysis pointed strongly toward metabolic reprogramming, with glycolysis and gluconeogenesis among the most significantly affected processes. Direct biochemical measurements confirmed the shift: glucose consumption, lactate production and intracellular ATP levels all fell when KIFC1 was silenced and rose when it was overexpressed, hallmarks of the Warburg effect that tumour cells exploit to fuel rapid proliferation.

The mechanistic thread connecting KIFC1 to metabolism runs through pyruvate kinase M, or PKM, the enzyme that catalyses the final, rate-limiting step of glycolysis. The PKM gene undergoes alternative splicing to yield two isoforms with opposing metabolic roles: PKM1 supports oxidative metabolism, whereas PKM2 favours aerobic glycolysis and is the dominant form in most tumours. When the researchers examined isoform expression after KIFC1 knockdown, they found PKM2 levels dropped while PKM1 rose, indicating that KIFC1 helps maintain the pro-glycolytic PKM2 balance that cervical cancer cells depend upon. The question was how a microtubule motor protein could influence a splicing decision buried in the cell’s gene-expression machinery.

The answer emerged from an unbiased proteomic approach. Using co-immunoprecipitation coupled with mass spectrometry, the team catalogued 1,067 proteins that physically associate with KIFC1, and among the enriched functional categories were spliceosome components and mRNA splicing processes. One candidate stood out: SRSF3, a serine/arginine-rich splicing factor previously shown to promote inclusion of PKM exon 10 and thereby tilt splicing toward PKM2. Co-immunoprecipitation experiments confirmed that KIFC1 and SRSF3 interact in cervical cancer cells, and database analysis revealed a robust correlation between the two genes in patient tumours. Intriguingly, KIFC1 knockdown did not change total SRSF3 abundance. Instead, nuclear and cytoplasmic fractionation combined with confocal immunofluorescence microscopy showed that depleting KIFC1 reduced the amount of SRSF3 in the nucleus and increased its cytoplasmic accumulation, suggesting that the motor protein acts as a shuttle that delivers the splicing factor to its site of action rather than as a regulator of its production.

Follow-up experiments cemented SRSF3 as the functional intermediary. Silencing SRSF3 in HeLa and SiHa cells suppressed proliferation, migration and all three glycolytic readouts, mirroring the effects of KIFC1 depletion. RNA immunoprecipitation demonstrated that SRSF3 binds directly to PKM messenger RNA, and its loss reproduced the isoform shift, raising PKM1 and lowering PKM2. Most persuasively, rescue experiments showed that restoring SRSF3 in KIFC1-depleted cells partially reversed the suppression of proliferation, migration, glucose consumption, lactate production and ATP generation, and re-established the PKM2-dominant profile. Taken together, these results delineate a coherent KIFC1–SRSF3–PKM axis in which a transport motor governs the subcellular localisation of a splicing factor, which in turn dictates a metabolic enzyme isoform switch that sustains the glycolytic appetite of the tumour.

What elevates this finding from an interesting piece of cell biology to a potentially transformative therapeutic insight is its connection to radiotherapy. Aerobic glycolysis is increasingly recognised as a driver of radioresistance because it supplies the energy and biosynthetic intermediates needed for DNA repair and helps tumour cells buffer the oxidative stress inflicted by radiation. When the researchers exposed KIFC1-silenced cells to graded doses of irradiation, clonogenic survival dropped significantly, particularly at 4 Gy and above, and radiation-induced apoptosis increased. Pharmacological activation of PKM2 with the selective activator TEPP-46 partially restored proliferative capacity and blunted the apoptotic response, demonstrating that the radiosensitising effect of KIFC1 loss depends on PKM2-driven glycolysis. Restoring SRSF3 produced a similar partial rescue, confirming the pathway’s role in the radiation response.

DNA damage assays provided a mechanistic window into why glycolytic disruption sensitises cells to radiation. After 4 Gy irradiation, KIFC1-depleted cells displayed elevated γ-H2AX fluorescence, a marker of DNA double-strand breaks, along with increased 53BP1 recruitment and reduced RAD51 foci, indicating impaired homologous recombination repair. Both SRSF3 restoration and TEPP-46 treatment partially reversed these changes, reinforcing the idea that a glycolysis-competent state is required for tumour cells to mend radiation-induced damage efficiently. The team then translated these findings into vivo using subcutaneous xenografts in nude mice. KIFC1 knockdown alone suppressed tumour growth, and combining it with a 6 Gy focal dose of irradiation produced significantly slower tumour growth than either intervention alone, accompanied by reduced Ki-67 staining and the same PKM isoform shift observed in culture. The authors candidly note that the in vivo effect was one of tumour growth delay rather than complete regression, a discrepancy they attribute to the complexity of the tumour microenvironment, including hypoxia, stromal interactions and the metabolic plasticity that allows tumours to compensate by activating alternative energy pathways.

The study does carry limitations that the authors themselves acknowledge. Validation in larger clinical cohorts will be needed to firmly establish KIFC1 as a prognostic and predictive biomarker, the precise splicing sites mediating SRSF3’s control of PKM in cervical cancer were not directly mapped, and the molecular determinants of the KIFC1–SRSF3 interaction, including possible adaptor proteins, remain to be identified. Nevertheless, the work expands the functional repertoire of KIFC1 well beyond mitosis, revealing a post-transcriptional mechanism by which intracellular transport machinery shapes metabolic adaptation and therapeutic resistance. If pharmacological inhibitors of this axis can be developed or repurposed, clinicians may one day combine them with radiotherapy to strip cervical tumours of the metabolic armour that currently lets them survive treatment, offering new hope for patients whose disease has stopped responding to conventional care.

Subject of Research: The role of the KIFC1–SRSF3–PKM splicing–metabolic axis in cervical cancer glycolysis and radiosensitivity

Article Title: Targeting the KIFC1‐SRSF3‐PKM Axis Suppresses Cervical Cancer Glycolysis and Enhances Radiosensitivity

Article References: Liu, J., Li, J., Zhou, H., Ha, W., Wu, X., Liu, X., Jiang, Y., Gong, C., Cheng, Y., Liu, Q., Chao, T., & Xiong, H. (2026). Targeting the KIFC 1‐ SRSF 3‐ PKM Axis Suppresses Cervical Cancer Glycolysis and Enhances Radiosensitivity. Journal of Cellular and Molecular Medicine, 30(18), Article e71373. https://doi.org/10.1111/jcmm.71373

Image Credits: AI Generated

DOI: 10.1111/jcmm.71373

Keywords: cervical cancer, KIFC1, SRSF3, PKM2, glycolysis, radioresistance, alternative splicing, Warburg effect, DNA damage repair, kinesin motor protein, radiosensitivity, tumour metabolism