SerpinB7 promotes c-Myc-mediated glycolysis by interacting with ANXA2 to facilitate the progression of non-small cell lung cancer

Non-small cell lung cancer, or NSCLC, represents approximately 85% of lung cancer cases. Its major histological forms include lung adenocarcinoma and lung squamous cell carcinoma. Although targeted treatments and immunotherapies have improved outcomes for selected patients, tumor heterogeneity, metastatic progression and acquired treatment resistance remain major challenges. Reference : National Cancer Institute

One biological feature connecting many forms of NSCLC is metabolic reprogramming. Cancer cells modify the way they obtain and use nutrients to support rapid proliferation, redox balance, macromolecule synthesis and survival under stress.

A central component of this adaptation is aerobic glycolysis, commonly called the Warburg effect. In this state, cancer cells convert large quantities of glucose into lactate even when oxygen is available. Although glycolysis generates less ATP per glucose molecule than mitochondrial oxidative phosphorylation, it can provide rapidly dividing cells with metabolic intermediates required for nucleotide, lipid and amino-acid synthesis.

NSCLC metabolism is not uniform. Lung adenocarcinoma and lung squamous cell carcinoma can show different levels of glucose dependence, and substantial metabolic heterogeneity may exist among patients and even among different regions of the same tumor. Nevertheless, increased glycolytic activity is an important feature of many aggressive NSCLC tumors and is associated with proliferation, invasion, immune regulation and treatment resistance. Reference : Pubmed

SerpinB7, encoded by the SERPINB7 gene, belongs to the intracellular clade B serpin family. Serpins are traditionally known as endogenous regulators of proteases, but some members also perform non-canonical functions through protein-protein interactions.

Image Reference : Wikipedia

Before the recent NSCLC study, SerpinB7 was primarily investigated in epithelial biology and inherited skin-barrier disorders. Its role in cancer metabolism was much less clearly defined.

The 2026 investigation found that SerpinB7 was elevated in NSCLC tumor tissues and that increased expression was associated with an unfavorable prognosis. Functional experiments involving SerpinB7 knockdown and overexpression further indicated that the protein influences several malignant characteristics, including:

- Cancer-cell proliferation and colony formation

- Migration and invasion

- Glucose uptake and utilization

- Lactate and ATP production

- Glycolytic flux

- Tumor formation and metastatic progression

These observations positioned SerpinB7 as more than a conventional protease inhibitor. Instead, it appeared to function as an oncogenic regulator connecting protein stability with cancer-cell metabolism.

An important result was that the metabolic effects of SerpinB7 did not depend entirely on its conventional serpin enzymatic mechanism.

The researchers modified amino-acid residues within the reactive center associated with classical protease inhibition. Despite reduced protease-related activity, the altered SerpinB7 protein retained its ability to promote glycolysis, proliferation, migration and invasion.

This suggested that SerpinB7 operates through a protease-independent regulatory function. Protein-interaction studies, including proteomic analysis, GST pull-down experiments, immunoprecipitation and mass spectrometry, subsequently identified ANXA2 as an important SerpinB7-binding partner.

Annexin A2, encoded by ANXA2, is a calcium-dependent phospholipid-binding protein with diverse intracellular and extracellular functions. It participates in membrane organization, cytoskeletal dynamics, vesicle trafficking, fibrinolysis and RNA regulation.

ANXA2 is frequently dysregulated in cancer and has been associated with tumor-cell migration, epithelial-mesenchymal transition, invasion, treatment resistance and poor prognosis. It can also function as an RNA-binding protein and interact with regulatory regions of c-Myc mRNA.

The NSCLC study demonstrated that SerpinB7 directly interacts with ANXA2. This interaction protects ANXA2 from degradation and allows it to accumulate inside cancer cells.

Image Reference : Wikipedia

Cellular protein abundance is controlled partly through ubiquitination. During this process, ubiquitin molecules are attached to a target protein, frequently marking it for degradation by the proteasome.

The E3 ubiquitin ligase NEDD4L was identified as a regulator of ANXA2 ubiquitination. Under normal regulatory conditions, NEDD4L contributes to the removal of ANXA2. SerpinB7 interferes with this process by competing with NEDD4L for interaction with ANXA2.

Consequently:

- ANXA2 ubiquitination is reduced.

- Proteasomal degradation of ANXA2 decreases.

- ANXA2 protein stability increases.

- More ANXA2 becomes available to regulate c-Myc.

- The c-Myc glycolytic program becomes more active.

The pathway can therefore be summarized as :

SerpinB7 upregulation → reduced NEDD4L-mediated ANXA2 ubiquitination → ANXA2 stabilization → increased c-Myc activity → enhanced glycolysis and NSCLC progression.

c-Myc is a major transcriptional regulator of cancer metabolism. It supports glucose uptake and controls genes involved in glycolysis, glutamine metabolism, mitochondrial function, nucleotide synthesis and cell growth.

The study provides evidence that ANXA2 affects c-Myc at several levels.

Increased c-Myc mRNA stability :

=> ANXA2 can bind regulatory regions of c-Myc mRNA. Stabilization of ANXA2 by SerpinB7 was associated with an extended c-Myc mRNA half-life, reducing the rate at which the transcript was degraded.

Enhanced c-Myc translation :

=> Polysome-profiling experiments showed that SerpinB7 overexpression shifted c-Myc mRNA toward heavier polysome fractions. This is consistent with increased translational efficiency and greater production of c-Myc protein.

Increased transcription of glycolytic genes :

Higher c-Myc activity increased its association with the promoters of several glycolysis-related genes, including:

- LDHA, which supports the conversion of pyruvate into lactate

- PKM2, which participates in the final ATP-generating stage of glycolysis

- ENO1, which catalyzes the conversion of 2-phosphoglycerate into phosphoenolpyruvate

- TPI1, which interconverts glycolytic triose-phosphate intermediates

The experiments showed that c-Myc overexpression could restore glycolysis and malignant behavior after ANXA2 suppression. Conversely, c-Myc knockdown reduced the tumor-promoting effects caused by ANXA2 overexpression.

These rescue experiments support a causal model in which the ANXA2-c-Myc pathway mediates the glycolytic and oncogenic effects of SerpinB7.

Activation of the SerpinB7-ANXA2-c-Myc axis produced measurable changes in glucose metabolism.

ANXA2 overexpression increased glucose consumption, 2-NBDG glucose uptake, lactate production, ATP abundance, extracellular acidification and glycolytic proton-efflux measurements. ANXA2 knockdown produced the opposite pattern.

SerpinB7 manipulation influenced these metabolic measurements through ANXA2. Restoring ANXA2 expression after SerpinB7 knockdown rescued much of the lost glycolytic activity. Suppressing ANXA2 in SerpinB7-overexpressing cells reduced glycolysis and malignant behavior.

The metabolic phenotype was accompanied by changes in:

- Clonogenic growth

- Cell proliferation

- Migration

- Extracellular-matrix invasion

- Apoptotic cell death

- Orthotopic lung tumor growth

- Metastatic dissemination

These findings indicate that glycolysis is not simply correlated with SerpinB7 expression. It appears to be a functional component of the malignant phenotype generated by the SerpinB7-ANXA2 pathway.

SerpinB7 may represent an attractive experimental target because it acts upstream of several metabolic outputs. Instead of inhibiting an individual glycolytic enzyme, SerpinB7 suppression could simultaneously reduce ANXA2 stability, c-Myc activity and the expression of multiple glycolytic genes.

The researchers developed a SerpinB7-targeting siRNA enclosed within an engineered ferritin nanocarrier. Ferritin nanocages possess an internal cavity capable of carrying molecular cargo and can interact with transferrin receptor 1, which is frequently elevated in cancer cells.

In orthotopic mouse models, the siRNA-containing ferritin construct accumulated in lung tumor tissue, reduced SerpinB7 expression and suppressed tumor growth and metastasis. The evaluated organs did not show obvious short-term histopathological injury under the reported experimental conditions.

However, this remains a preclinical therapeutic strategy. Important questions still need to be resolved:

- Is SerpinB7 consistently elevated across genetically diverse human NSCLC tumors?

- Which patients are most likely to depend on the SerpinB7–ANXA2 axis?

- Could tumors bypass SerpinB7 inhibition by activating HIF-1α, PI3K–AKT–mTOR or alternative metabolic pathways?

- How selective would SerpinB7 inhibition be for tumor cells relative to normal epithelial tissues?

- Is systemic siRNA delivery safe after repeated or long-term administration?

- Would SerpinB7 suppression improve responses to chemotherapy, targeted therapy or immunotherapy?

The study itself notes that the long-term biosafety of the ferritin-based siRNA formulation requires further investigation. The published version was also identified as an early, unedited article-in-press manuscript at the time of its release.

Metabolic inhibition does not automatically demonstrate cancer-cell death. A reduction in ATP, glucose uptake or colony formation may result from growth arrest, senescence, metabolic adaptation or apoptosis. Researchers studying SerpinB7, ANXA2 or c-Myc should therefore combine metabolic measurements with direct cell-death assays.

A useful experimental workflow may include :

1- Suppression of SERPINB7, ANXA2 or MYC using siRNA, shRNA or CRISPR-based approaches.

2- Confirmation of target knockdown by quantitative PCR and western blotting.

3- Measurement of glucose uptake, lactate production, ATP and extracellular acidification.

4- Analysis of LDHA, PKM2, ENO1, TPI1 and other metabolic targets.

5- Quantification of proliferation, colony formation, migration and invasion.

6- Flow-cytometric measurement of early and late apoptosis.

7- Rescue experiments in which ANXA2 or c-Myc is restored.

8- Validation in organoid, xenograft or orthotopic NSCLC models.

For apoptosis analysis, the Annexin V-APC/7-AAD Apoptosis Kit available from Gentaur can be integrated into cell-based pathway studies.

The assay combines APC-labelled Annexin V with 7-AAD. Annexin V detects phosphatidylserine exposure on the outer surface of apoptotic cells, while 7-AAD identifies cells that have lost plasma-membrane integrity. This combination supports discrimination among viable cells, early apoptotic cells and late apoptotic or membrane-compromised cells by flow cytometry.

ANXA2, or Annexin A2, is the signaling and RNA-binding protein involved in the SerpinB7–c-Myc pathway.

Annexin V is a separate phosphatidylserine-binding protein used as a laboratory reagent for apoptosis detection.

An Annexin V apoptosis kit does not directly quantify ANXA2 expression. Instead, it measures a functional downstream outcome whether experimental disruption of SerpinB7, ANXA2 or c-Myc increases apoptotic cell death.

Proper experiments should include untreated controls, a positive apoptosis control, single-stain controls, fluorescence-compensation controls and collection of both attached and floating cells. Excluding floating cells can underestimate treatment-induced apoptosis.

The discovery of the SerpinB7-ANXA2-c-Myc axis expands the understanding of metabolic reprogramming in non-small cell lung cancer in three important ways.

First, it assigns a previously underrecognized oncogenic function to SerpinB7. The protein promotes NSCLC through a non-canonical mechanism rather than solely through classical protease inhibition.

Second, it identifies control of protein stability as an upstream regulator of cancer glycolysis. By preventing ANXA2 ubiquitination, SerpinB7 indirectly amplifies a broad c-Myc-dependent metabolic program.

Third, it suggests a possible therapeutic strategy for simultaneously disrupting tumor metabolism and malignant behavior. Targeting SerpinB7 may affect glucose utilization, proliferation, invasion and metastatic competence rather than inhibiting only one downstream enzyme.

These findings also reinforce the importance of examining metabolic pathways as interconnected regulatory networks. Glycolysis in cancer is controlled not only by metabolic enzymes but also by ubiquitin ligases, RNA-binding proteins, transcription factors and protein–protein interactions.

SerpinB7 has emerged as a potential driver of metabolic reprogramming in non-small cell lung cancer. By interacting with ANXA2 and limiting its NEDD4L-mediated ubiquitination, SerpinB7 stabilizes ANXA2 and strengthens c-Myc-dependent glycolytic signaling.

The resulting increase in glucose uptake, lactate production, ATP generation and glycolytic-gene expression supports NSCLC proliferation, invasion and metastasis. Genetic suppression of SerpinB7 reduced these malignant phenotypes, while ferritin-mediated delivery of SerpinB7 siRNA showed antitumor activity in preclinical mouse models.

The SerpinB7–ANXA2–c-Myc pathway therefore represents a promising metabolic vulnerability. Nevertheless, clinical translation will require independent patient-cohort validation, biomarker development, long-term safety testing and evidence that SerpinB7 inhibition can produce durable benefits across heterogeneous NSCLC subtypes.

What does SerpinB7 do in non-small cell lung cancer?

=> SerpinB7 binds to ANXA2 and protects it from NEDD4L-mediated ubiquitination and degradation. The accumulated ANXA2 enhances c-Myc expression and activity, leading to increased glycolysis, proliferation, invasion and tumor progression.

How does ANXA2 regulate c-Myc?

=> ANXA2 functions as an RNA-binding protein. In the reported NSCLC model, it promoted c-Myc mRNA stability and translational efficiency. Increased c-Myc subsequently enhanced the transcription of glycolytic genes such as LDHA, PKM2, ENO1 and TPI1.

Why do NSCLC cells increase glycolysis?

=> Increased glycolysis provides rapidly proliferating cancer cells with ATP and metabolic intermediates needed for biosynthesis. It may also support redox regulation, adaptation to hypoxia, metastatic behavior and resistance to anticancer treatment.

Is SerpinB7 already a validated NSCLC treatment target?

=> No. SerpinB7 is currently an experimental target. SerpinB7-directed siRNA reduced tumor growth in preclinical mouse models, but no approved SerpinB7-targeted therapy has been established for patients with NSCLC.

Does an Annexin V apoptosis kit measure ANXA2?

=> No. Annexin V and Annexin A2 are different proteins. Annexin V detects phosphatidylserine exposure during apoptosis. ANXA2 is the signaling and RNA-binding protein stabilized by SerpinB7.

How can apoptosis be measured after SerpinB7 knockdown?

=> Cells can be stained with APC-labelled Annexin V and 7-AAD and analyzed by flow cytometry. Annexin V-positive/7-AAD-negative cells are generally classified as early apoptotic, while double-positive cells are generally associated with late apoptosis or loss of membrane integrity.

1- Zhao F, Zeng F, Zhou P, et al. SerpinB7 promotes c-Myc-mediated glycolysis by interacting with ANXA2 to facilitate the progression of non-small cell lung cancer

2- NCBI Gene: SERPINB7

3- NCBI Gene: ANXA2

4- Targeting glycolysis in non-small cell lung cancer: promises and challenges

5- NCI overview of lung cancer treatment

6- Annexin V-APC/7-AAD Apoptosis Kit for flow-cytometric cell-death analysis