It is well known that high-risk human papilloma virus (HR-HPV) infection is strongly associated with cervical cancer and E7 was identified as one of the key initiators in HPV-mediated carcinogenesis. Here we show that lactate dehydrogenase A (LDHA) preferably locates in the nucleus in HPV16-positive cervical tumors due to E7-induced intracellular reactive oxygen species (ROS) accumulation. Surprisingly, nuclear LDHA gains a non-canonical enzyme activity to produce α-hydroxybutyrate and triggers DOT1L (disruptor of telomeric silencing 1-like)-mediated histone H3K79 hypermethylation, resulting in the activation of antioxidant responses and Wnt signaling pathway. Furthermore, HPV16 E7 knocking-out reduces LDHA nuclear translocation and H3K79 tri-methylation in K14-HPV16 transgenic mouse model. HPV16 E7 level is significantly positively correlated with nuclear LDHA and H3K79 tri-methylation in cervical cancer. Collectively, our findings uncover a non-canonical enzyme activity of nuclear LDHA to epigenetically control cellular redox balance and cell proliferation facilitating HPV-induced cervical cancer development.

Background/Aim: Surgery and chemotherapy treatments of human laryngeal squamous cell carcinoma (HLSCC) may fail due to metastasis, in which epithelial-mesenchymal transition (EMT) plays an important role. TRPP2, a nonselective cation channel, is expressed in various cell types and participates in many biological processes. Here, we show that TRPP2 enhanced metastasis by regulating EMT. Methods: We used immunohistochemistry, western blotting, Ca²⁺ imaging, transwell and wound healing assays to investigate TRPP2 expression levels in HLSCC tissue, and the role of TRPP2 in invasion and metastasis of a human laryngocarcinoma cell line (Hep2 cell). Results: We found that TRPP2 protein expression levels were significantly increased in HLSCC tissue; higher TRPP2 levels were associated with decreased patient survival time and degree of differentiation and advanced clinical stage. Knockdown of TRPP2 by transfection with TRPP2 siRNA markedly suppressed ATP-induced Ca²⁺ release, wound healing, and cell invasion in Hep2 cells. Moreover, TRPP2 siRNA significantly decreased vimentin expression but increased E-cadherin expression in Hep2 cells. In the EMT signalling pathway, TRPP2 siRNA significantly decreased Smad4, STAT3, SNAIL, SLUG and TWIST expression in Hep2 cells. Conclusion: We revealed a previously unknown function of TRPP2 in cancer development and a TRPP2-dependent mechanism underlying laryngocarcinoma cell invasion and metastasis. Our results suggest that TRPP2 may be used as a biomarker for evaluating patient prognosis and as a novel therapeutic target in HLSCC.

The flow-stimulated intracellular Ca2+ concentration ([Ca2+]i) rise in endothelial cells is an important early event leading to flow-induced blood vessel dilation. Transient receptor potential vanilloid subtype 4 (TRPV4), a Ca2+-permeable cation channel, facilitates the flow-stimulated [Ca2+]i rise. To determine whether TRPV4 is involved in age-related flow-induced blood vessel dilation impairment, we measured blood vessel diameter and nitric oxide (NO) levels and performed Ca2+ imaging, immunoblotting, and immunostaining assays in rats. We found that the flow-induced and TRPV4 activator 4α-PDD-induced dilation of mesenteric arteries from aged rats were significantly decreased compared with those from young rats. The flow- or 4α-PDD-induced [Ca2+]i rise was also markedly reduced in primary cultured mesenteric artery endothelial cells (MAECs) from aged rats. Immunoblotting and immunostaining results showed an age-related decrease of TRPV4 expression levels in MAECs. Additionally, the 4α-PDD-induced NO production was significantly reduced in aged MAECs. Compared with lentiviral GFP-treated aged rats, lentiviral vector delivery of TRPV4 increased TRPV4 expression level in aged MAECs and restored the flow- and 4α-PDD-induced vessel dilation in aged mesenteric arteries. We concluded that impaired TRPV4-mediated Ca2+ signaling causes endothelial dysfunction and that TRPV4 is a potential target for clinical treatment of age-related vascular system diseases.

Phospholipid scramblase 1 (PLSCR1), a lipid-binding and Ca2+-sensitive protein located on plasma membranes, is critically involved in phosphatidylserine (PS) externalization, an important process in cell apoptosis. Transient receptor potential canonical 5 (TRPC5), is a nonselective Ca2+ channel in neurons that interacts with many downstream molecules, participating in diverse physiological functions including temperature or mechanical sensation. The interaction between TRPC5 and PLSCR1 has never been reported. Here, we showed that PLSCR1 interacts with TRPC5 through their C-termini in HEK293 cells and mouse cortical neurons. Formation of TRPC5-PLSCR1 complex stimulates PS externalization and promotes cell apoptosis in HEK293 cells and mouse cerebral neurons. Furthermore, in vivo studies showed that PS externalization in cortical neurons induced by artificial cerebral ischemia-reperfusion was reduced in TRPC5 knockout mice compared to wild-type mice, and that the percentage of apoptotic neurons was also lower in TRPC5 knockout mice than in wild-type mice. Collectively, the present study suggested that TRPC5-PLSCR1 is a signaling complex mediating PS externalization and apoptosis in neurons and that TRPC5 plays a pathological role in cerebral-ischemia reperfusion injury.

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