Scientists Activate NK Cells' Anti-Cancer Potential And Directly Target Key Tumor Metastasis

Data from the World Health Organization show that of the approximately 19.3 million new cancer cases worldwide each year, 10 million people die from cancer. Although immune checkpoint inhibitors (such as PD-1 antibodies) have revolutionized cancer treatment, a large number of patients still face the problem of "no response" or "drug resistance". Among them, natural killer cells (NK cells) are the first line of defense against cancer, and their activity is often inhibited by the tumor microenvironment. IL-15, as a core cytokine that regulates NK cell function, can enhance the killing ability of NK cells, but its clinical application is limited by the toxicity of systemic administration (such as cytokine storm).

The study of the Australian oNKo-innate company and the Monash University team in "Cancer Cell" revealed that tumor cells can degrade the IL-15 receptor (IL-15R) mediated by the UBE2F and ARIH2 genes, weakening the sensitivity of NK cells to IL-15. Targeting this mechanism can not only avoid systemic toxicity, but also specifically activate the anti-cancer ability of NK cells in the tumor.

In this study, the research team used CRISPR-Cas9 technology to perform whole-genome screening in human NK cells. Using low-dose IL-15 that simulates the physiological concentration in the tumor microenvironment as the screening pressure, it was found that UBE2F (NEDD8 E2 ligase) and ARIH2 (ubiquitin E3 ligase) are key factors that inhibit IL-15R signals. Moreover, after knocking out these two genes, the expression of IL-15R (CD122) on the surface of NK cells increased by 2 times, and the sensitivity to IL-15 was significantly enhanced!

By further exploring its molecular mechanism, the researchers found that UBE2F activates the CRL5 ubiquitin ligase complex by catalyzing the Neddylation modification of CUL5 protein; and ARIH2, as a key component of the CRL5 complex, directly mediates the ubiquitination degradation of IL-15R. When UBE2F or ARIH2 is missing, IL-15R is protected from degradation and continuously activates the JAK-STAT5 signaling pathway, thereby promoting NK cell proliferation, secreting cytokines such as IFN-γ and TNF-α, and upregulating the expression of killer receptors such as NKp30 and NKG2D.

Verification of the "anti-cancer superpower" of gene-edited NK cells

(1) In vitro experiments: Fighting tumor "fatigue" and immunosuppression

Anti-fatigue ability: In four consecutive rounds of tumor cell killing experiments, the killing efficiency of NK cells with UBE2F/ARIH2 knockout was 50% higher than that of the control group, and the resistance to immunosuppressive factors such as adenosine and TGF-β was significantly enhanced.

CAR-NK cell upgrade: In CAR-NK cells targeting BCMA, UBE2F was knocked out, and its killing efficiency against drug-resistant leukemia cells remained at the initial level in the third round of challenge, and IFN-γ secretion increased by 3 times.

(2) Animal model: Direct attack on primary and metastatic tumors

Lung metastasis model: In mice with Arih2/Ube2f knockout, the number of B16F10 melanoma lung metastases decreased by 60%, and NK cell activity was significantly improved.

Colorectal cancer model: The growth rate of MC38 tumors in Ube2f knockout mice was slowed by 70%, the proportion of CD122+NK cells in the tumor microenvironment increased, and the proportion of Granzyme B+ cytotoxic cells increased by 2 times.

Figure 1. In mice with knockout of Ube2f, Arih2 or Rnf7 genes, the growth of primary and metastatic tumors in vivo was significantly inhibited, with a 60% reduction in metastatic lesions in the lung metastasis model and a 70% reduction in tumor volume in the colorectal cancer model. (Nikolic, Iva, et al. 2025)

From the laboratory to the clinic

Traditional IL-15 agonists are prone to toxicity due to activation of peripheral immune cells, while targeting UBE2F/ARIH2 only selectively enhances the response of local NK cells in tumors to IL-15. Experiments show that Ube2f knockout mice do not have inflammatory responses caused by IL-15 overexpression, and their safety is significantly better than traditional therapies.

At the drug development level, UBE2F inhibitors can maintain IL-15R surface expression by blocking CUL5 activation, while ARIH2 inhibitors can directly block the ubiquitination degradation of IL-15R. Studies have shown that the NEDDylation inhibitor Pevonedistat can mimic the effects of UBE2F deficiency. Although the dose needs to be optimized to reduce cytotoxicity, it provides a clear direction for the development of small molecule drugs.

In summary, in response to the problem of "poor persistence" faced by current CAR-NK therapy, this study confirmed that knocking out UBE2F/ARIH2 can enhance the anti-fatigue ability of CAR-NK cells, and its mechanism may be related to the continuous activation of the mTOR pathway and enhanced glucose metabolism. This discovery provides a theoretical basis for the combination therapy of "gene editing and CAR-NK", which is expected to break through the bottleneck of the treatment of hematological tumors and solid tumors.