IGF2BP3 enhances lipid metabolism in cervical cancer by upregulating the expression of SCD

Cervical cancer remains a leading cause of cancer morbidity and mortality among women globally, with rising incidence in younger populations. While dysregulated metabolism, especially lipid metabolism, supports tumor growth and metastasis, the molecular links between lipid metabolic reprogramming and CC progression are not fully understood. RNA-binding proteins (RBPs) are key post-transcriptional regulators implicated in cancer biology. IGF2BP3, an RBP and m6A reader, has been associated with enhanced proliferation and migration in multiple cancers, but its role in CC and lipid metabolism is unclear. The study investigates whether IGF2BP3 is overexpressed in CC, its association with clinical stage, and tests the hypothesis that IGF2BP3 promotes CC proliferation, metastasis, and lipid metabolism by stabilizing SCD mRNA via m6A-dependent mechanisms.

The authors contextualize their work by noting that RBPs regulate RNA processing, stability, localization, and translation, and their dysregulation contributes to oncogenesis and metastasis. IGF2BP family members, including IGF2BP3, recognize m6A-modified RNAs to enhance mRNA stability and translation. Prior studies link IGF2BP3 to tumorigenesis across cancers (acute myeloid leukemia via RCC2; laryngeal squamous cell carcinoma via TMBIM6; breast cancer immune evasion via PD-L1; colon cancer cell cycle and angiogenesis via cyclin D1 and VEGF). Lipid metabolism is central to cancer cell energetics and signaling; SCD, a key desaturase converting saturated to monounsaturated fatty acids, is overexpressed in many tumors (lung, breast, colorectal, esophageal, bladder, liver). In CC specifically, multiple lipid metabolic regulators (FABP5, LNMICC, FASN, DECR1) have been implicated in progression and metastasis. However, IGF2BP3’s role in lipid metabolism and its downstream targets in CC had not been systematically studied prior to this work.

- Clinical samples and databases: IGF2BP3 and SCD expression analyzed using public databases (GEPIA, UALCAN, TNMplot, TCGA). Immunohistochemistry (IHC) performed on cervical cancer tissue microarrays (n=108) to compare tumor vs adjacent tissues, assess associations with stage, lymph node status, and grade; H-scores computed. Ki-67 and SCD IHC conducted on xenograft tumors. - Cell culture: HeLa and SiHa cervical cancer cell lines cultured in DMEM + 10% FBS, authenticated by STR and mycoplasma-negative. - Gene perturbations: siRNA-mediated knockdown of IGF2BP3, SCD, and METTL14; lentiviral shRNA for stable IGF2BP3 knockdown; SCD overexpression (rescue) in IGF2BP3-silenced cells. Selection with puromycin. - RNA-seq: Performed on IGF2BP3-knockdown vs control cells to identify differentially expressed genes; GO enrichment analyses (barplot, doughnut plots), heatmaps, and volcano plots to identify lipid metabolism-related genes and nominate SCD as a downstream target. - Proliferation and viability assays: CCK-8 viability assay; colony formation assay; EdU incorporation assay. - Migration and invasion: Transwell migration and Matrigel invasion assays; scratch wound-healing assays. - Cell cycle and apoptosis: Flow cytometry with PI staining for cell cycle and Annexin V-FITC/PI for apoptosis. - Lipid metabolism measurements: Oil Red O staining to visualize lipid droplets; triglyceride (TG) quantification with colorimetric kit; fatty acid profiling (C16:1 and C18:1 among others) by GC-MS after FAME derivatization. - RNA and protein analyses: qRT-PCR and western blot for gene and protein expression (lipid metabolism markers: Pparg, Fasn, Fabp4, C/ebpa; SCD, IGF2BP3; METTL14/METTL3). Co-immunoprecipitation (co-IP) where appropriate. - RNA binding and m6A assays: RNA immunoprecipitation (RIP) to test IGF2BP3 binding to SCD mRNA; m6A-RIP to assess m6A modification levels on SCD mRNA, including after METTL14 knockdown; RNA stability assays using actinomycin D chase to determine SCD mRNA half-life with/without IGF2BP3. - Immunofluorescence/confocal: Colocalization and expression of IGF2BP3 and SCD in cells. - In vivo studies: Subcutaneous xenografts in female BALB/c nude mice (n=5/group) with HeLa (and SiHa in supplemental) expressing shNC, shIGF2BP3+oe-NC, or shIGF2BP3+oe-SCD. Tumor volume tracking, IVIS imaging at days ~20 and ~30, tumor weight at endpoint, Ki-67 and SCD IHC, and Kaplan-Meier survival analysis. - Statistics: Student's t-test for two-group comparisons; one-way ANOVA for multiple groups; Kaplan-Meier with log-rank for survival; experiments repeated ≥3 times; significance at P<0.05.

- IGF2BP3 overexpression in CC: Public databases (TCGA/CESC, GEPIA, GETx; microarrays GSE7803, GSE9750) and IHC on TMA (n=108) showed IGF2BP3 significantly higher in CC versus adjacent tissues. IGF2BP3 expression positively correlated with higher clinical stage and adverse clinicopathologic features. Table 1 indicates significant associations with lymph node status (P=0.0117), grade (P=0.0069), and stage (P=0.0002). - Functional impact of IGF2BP3 knockdown: In HeLa and SiHa cells, siIGF2BP3 reduced viability (CCK-8), clonogenicity, and proliferation (EdU), decreased migration and invasion (transwell, wound-healing), increased apoptosis, and induced G1 arrest (flow cytometry). - Lipid metabolism effects: RNA-seq identified significant downregulation of 138 genes (HeLa) and 397 genes (SiHa) upon IGF2BP3 knockdown with enrichment for lipid metabolic processes. IGF2BP3 depletion reduced lipid droplets (Oil Red O), decreased cellular TG, and lowered monounsaturated fatty acids (C16:1 palmitoleic acid and C18:1 oleic acid) by GC-MS. Expression of lipid metabolism markers (Pparg, Fasn, Fabp4, C/ebpa) fell at mRNA and protein levels. - SCD is a downstream effector: Heatmaps and differential expression pointed to SCD as a target of IGF2BP3. SCD is upregulated in CC (GEPIA, UALCAN, TNMplot) and correlates with worse prognosis (TCGA survival). TMA IHC (n=108) confirmed higher SCD in tumors and positive correlation with IGF2BP3. Clinicopathologic associations for SCD were significant (lymph node status P=0.0117; grade P=0.0013; stage P=0.0002; Table 2). - m6A-dependent stabilization: IGF2BP3 knockdown shortened SCD mRNA half-life (actinomycin D chase). METTL14 knockdown (but not METTL3) decreased SCD expression and lipid-metabolism-related factors. m6A-RIP showed reduced m6A-modified SCD after METTL14 silencing; RIP showed decreased IGF2BP3-bound SCD in METTL14-silenced cells, indicating IGF2BP3 stabilizes SCD mRNA via METTL14-dependent m6A recognition. - Rescue by SCD overexpression: In IGF2BP3-silenced cells, SCD overexpression restored SCD and lipid gene expression, rescued proliferation/viability (CCK-8, colony, EdU), migration/invasion, reduced apoptosis, normalized cell cycle, and reinstated lipid droplets, TG, and MUFA levels (C16:1, C18:1). - In vivo validation: HeLa xenografts with shIGF2BP3 formed significantly smaller tumors with lower weight and reduced Ki-67; survival improved versus controls. Co-expression of SCD (shIGF2BP3+oe-SCD) partially rescued tumor growth and survival to levels similar to shNC. Tumor SCD IHC decreased with IGF2BP3 knockdown and increased with SCD overexpression. Similar findings were replicated with SiHa (supplementary).

The study addresses the question of how IGF2BP3 contributes to cervical cancer progression by linking it to lipid metabolic reprogramming. The data demonstrate that IGF2BP3 is clinically upregulated in CC and correlates with advanced disease. Mechanistically, IGF2BP3 functions as an m6A reader to stabilize SCD mRNA via a METTL14-dependent pathway, thereby increasing SCD expression. Elevated SCD augments monounsaturated fatty acid synthesis, promoting lipid droplet accumulation, triglyceride content, and downstream lipid metabolic gene programs, which in turn enhance tumor cell proliferation, survival, migration, and invasion. Functional rescue with SCD overexpression and in vivo xenograft experiments corroborate the centrality of the IGF2BP3–SCD axis. These findings integrate post-transcriptional m6A regulation with lipid metabolism to explain a pathway by which CC cells acquire metabolic advantages that support aggressive phenotypes, highlighting potential therapeutic targets within this axis.

This work establishes IGF2BP3 as an oncogenic driver in cervical cancer that promotes proliferation, metastasis, and lipid metabolism by stabilizing SCD mRNA through METTL14-dependent m6A recognition. Clinically, IGF2BP3 and SCD are overexpressed and associate with adverse tumor features. Genetic suppression of IGF2BP3 inhibits tumor growth and lipid metabolism, while SCD overexpression rescues these effects in vitro and in vivo. The study proposes the IGF2BP3/SCD/lipid metabolism axis as a promising therapeutic target in CC. Future research should validate these findings in larger, independent patient cohorts with outcome data, dissect additional IGF2BP3 mRNA targets influencing lipid metabolism, clarify METTL14’s broader role, and explore pharmacologic inhibitors or RNA-targeted strategies against IGF2BP3–SCD signaling.

- Predominant reliance on in vitro cell line models and subcutaneous xenografts may limit direct clinical translatability; orthotopic or patient-derived models and clinical cohorts with survival endpoints would strengthen generalizability. - While SCD is validated as a key mediator, IGF2BP3 likely regulates additional lipid metabolism-related transcripts; the full target spectrum and pathway crosstalk were not comprehensively mapped. - Sample size calculation was not performed; tissue microarray analyses (n=108) establish associations but do not prove causality; prospective validation is needed. - METTL14 dependence was shown, but upstream regulation of METTL14 and potential contributions of other m6A writers/erasers/readers require further investigation.