KCMF1 regulates autophagy and ion channels' function in renal cell carcinoma: a future therapeutic target

In RCC, systematic procedures such as surgery, chemo-radiation therapy, and application of target-based inhibitors increase the risk of several comorbidities such as chronic kidney disease, hemorrhage, and cardiac arrest that may increase the mortality rate. Even though immune-based checkpoint inhibitor therapies have an overall good response rate, it is restricted to only 30-40% of patients. Hence, an in-depth study of tumor pathophysiology in RCC is needed to identify the new therapeutic target. In RCC, persisted hypoxia is an essential phenomenon for tumor growth and progression. KCMF1 is a newly identified ubiquitin ligase whose domain interacts with destabilized proteins and reprogrammed the ubiquitin coding for lysosome-mediated degradation and autophagy under hypoxic conditions/oxidative stress and maintaining cellular homeostasis. But in RCC, the functional role of KCMF1 remains undefined to date.

We determined KCMF1 and its associated proteins RAD6 and UBR4 expression and their co-localization using confocal microscopy in tumor and non-tumor tissues samples. Further, immunofluorescence staining was performed to determine autophagy (LC3B, p62), hypoxia-inducible factor (HIF-1A) and ion channel markers (Kv1.3, KCNN4) in RCC patients (n-10). Inductively coupled plasma mass spectrophotometry (ICPMS) was performed to estimate the concentration of potassium (K⁺), sodium (Na⁺) and Zinc (zn²⁺) in tumor and non-tumor cells of RCC patients (n-20). Lastly, images were analyzed using ZEN3.1, and ImageJ software.

We observed a discrepancy in the formation of ubiquitin ligase, autophagosome via KCMF1, and ionic concentration in tumor cells, which might be one of the possible factors for cancer evolution. KCMF1-associated ubiquitin ligase system could be considered as a novel therapeutic target for RCC in the future.