Lin Lu

Background: HCC is one of the most common causes of cancer-related deaths. Transient receptor potential melastatin 2 (TRPM2), a Ca²⁺-permeable cation channel, was reported to be involved in carcinogenesis and tumor growth recently. However, whether TRPM2 is involved in the pathogenesis and progression of HCC remains unclear. Herein, we systematically elucidated the functional role of TRPM2 in HCC cell cycle regulation and proliferation. Approach and Results: We determine TRPM2 expression to be strongly upregulated in the tumor tissues of HCC patients and associated with a negative prognosis. TRPM2 is highly expressed in HCC cell lines Huh-7 and HepG2 cells, rather than in normal hepatocytes. Inhibition or silencing of TRPM2, or inhibition of the downstream Ca²⁺-CaM-CaMKII signaling pathway, significantly suppressed the proliferation of Huh-7 and HepG2 cells by arresting the cell cycle at the G1/S phase, accompanied with reduced expression of G1/S checkpoint proteins. Importantly, inhibition or depletion of TRPM2 remarkably slowed down the growth of patient-derived xenografts and Huh-7 xenografts in mice. Conclusion: Our results indicate that TRPM2 promotes HCC cell proliferation via activating the Ca²⁺-CaM-CaMKII signaling pathway to induce the expression of the key G1/S regulatory proteins and accelerate the cell cycle. This study provides compelling evidence of TRPM2 involvement in a previously unrecognized mechanism that drives HCC progression and demonstrates that TRPM2 is a potential target for HCC treatment.

Cerebral ischemia‐reperfusion (I‐R) transiently increased autophagy by producing excessively reactive oxygen species (ROS); on the other hand, activated autophagy would remove ROS‐damaged mitochondria and proteins, which led to cell survival. However, the regulation mechanism of autophagy activity during cerebral I‐R is still unclear. In this study, we found that deficiency of the TRPM2 channel which is a ROS sensor significantly decreased I‐R‐induced neuronal damage. I‐R transiently increased autophagy activity both in vitro and in vivo. More importantly, TRPM2 deficiency decreased I‐R‐induced neurological deficit score and infarct volume. Interestingly, our results indicated that TRPM2 deficiency could further activate AMPK rather than Beclin1 activity, suggesting that TRPM2 inhibits autophagy by regulating the AMPK/mTOR pathway in I‐R. In conclusion, our study reveals that ROS‐activated TRPM2 inhibits autophagy by downregulating the AMPK/mTOR pathway, which results in neuronal death induced by cerebral I‐R, further supporting that TRPM2 might be a potential drug target for cerebral ischemic injury therapy.