Erratum to: Inhibition of TRPM7 suppresses cell proliferation of colon adenocarcinoma in vitro and induces hypomagnesemia in vivo without affecting azoxymethane-induced early colon cancer in mice

The role of transient receptor potential channels in metastasis

Metastasis is the hallmark of failed tumor treatment and is typically associated with death due to cancer. Transient receptor potential (TRP) channels affect changes in intracellular calcium concentrations and participate at every stage of metastasis. Further, they increase the migratory ability of tumor cells, promote angiogenesis, regulate immune function, and promote the growth of tumor cells through changes in gene expression and function. In this review, we explore the potential mechanisms of action of TRP channels, summarize their role in tumor metastasis, compile inhibitors of TRP channels relevant in tumors, and discuss current challenges in research on TRP channels involved in tumor metastasis.

TRPM7 Induces Tumorigenesis and Stemness Through Notch Activation in Glioma

We have reported that transient receptor potential melastatin-related 7 (TRPM7) regulates glioma stem cells (GSC) growth and proliferation through Notch, STAT3-ALDH1, and CD133 signaling pathways. In this study, we determined the major contributor(s) to TRPM7 mediated glioma stemness by further deciphering each individual Notch signaling. We first determined whether TRPM7 is an oncotarget in glioblastoma multiforme (GBM) using the Oncomine database. Next, we determined whether TRPM7 silencing by siRNA TRPM7 (siTRPM7) induces cell growth arrest or apoptosis to reduce glioma cell proliferation using cell cycle analysis and annexin V staining assay. We then examined the correlations between the expression of TRPM7 and Notch signaling activity as well as the expression of GSC markers CD133 and ALDH1 in GBM by downregulating TRPM7 through siTRPM7 or upregulating TRPM7 through overexpression of human TRPM7 (M7-wt). To distinguish the different function of channel and kinase domain of TRPM7, we further determined how the α-kinase-dead mutants of TRPM7 (α-kinase domain deleted/M7-DK and K1648R point mutation/M7-KR) affect Notch activities and CD133 and ALDH1 expression. Lastly, we determined the changes in TRPM7-mediated regulation of glioma cell growth/proliferation, cell cycle, and apoptosis by targeting Notch1. The Oncomine data revealed a significant increase in TRPM7 mRNA expression in anaplastic astrocytoma, diffuse astrocytoma, and GBM patients compared to that in normal brain tissues. TRPM7 silencing reduced glioma cell growth by inhibiting cell entry into S and G2/M phases and promoting cell apoptosis. TRPM7 expression in GBM cells was found to be positively correlated with Notch1 signaling activity and CD133 and ALDH1 expression; briefly, downregulation of TRPM7 by siTRPM7 decreased Notch1 signaling whereas upregulation of TRPM7 increased Notch1 signaling. Interestingly, kinase-inactive mutants (M7-DK and M7-KR) resulted in reduced activation of Notch1 signaling and decreased expression of CD133 and ALDH1 compared to that of wtTRPM7. Finally, targeting Notch1 effectively suppressed TRPM7-induced growth and proliferation of glioma cells through cell G1/S arrest and apoptotic induction. TRPM7 is responsible for sustained Notch1 signaling activation, enhanced expression of GSC markers CD133 and ALDH1, and regulation of glioma stemness, which contributes to malignant glioma cell growth and invasion.

A bibliometric analysis and review of recent researches on TRPM7

The transient receptor potential melastatin-subfamily member 7 (TRPM7) is a ubiquitously expressed protein that contains both an ion channel and an active kinase. TRPM7 has involved in a variety of cellular functions and critically participates in various diseases mainly including cancer and neurodegenerative disorders. However, the theme trends and knowledge structures for TRPM7 have not yet been studied bibliometrically. The main purposes of this research are to compare the scientific production in the research field of TRPM7 among countries and to evaluate the publication trend between 2004 and 2019. All publications were extracted from the Web of Science Core Collection (WoSCC) database from 2004 to 2019. Microsoft Excel 2018, Prism 6, and CiteSpace V were applied to analyze the scientific research outputs including journals, countries, territories, institutions, authors, and research hotspots. In this report, a total of 860 publications related to TRPM7 were analyzed. Biophysical Journal ranked top for publishing 31 papers. The United States of America had the largest number of publications (320) with a high citation frequency (11,298) and H-index (58). Chubanov V (38 publications) and Gudermann T (38 citations), who from Ludwig Maximilian University of Munich, were the most productive authors and had the greatest co-citation counts. Our study also combined the bibliometric study with a systematic review on TRPM7, highlighting the four research frontiers of TRPM7. This is the first study that demonstrated the trends and future development in TRPM7 publications, providing a clear and intuitive profile for the contributions in this field.

TRPM7 promotes the epithelial-mesenchymal transition in ovarian cancer through the calcium-related PI3K / AKT oncogenic signaling

BACKGROUND

The epithelial-mesenchymal transition (EMT) is crucial for metastasis and positively regulated by calcium-related signaling. The melastatin-related transient receptor potential 7 (TRPM7) regulates a non-selective cation channel and promotes cancer metastasis. However, the mechanisms underlying the action of TRPM7 in ovarian cancer are unclear.

METHODS

The expression of TRPM7 and EMT markers (Vimentin, N-cadherin, Twist and E-cadherin) in ovarian cancer samples was detected. TRPM7was knockdown by shRNA in Ovarian cancer cell lines to examine calcium [Ca2+]i, EMT markers and PI3K/AKT markers. Various cellular assays, such as invasion and migration, were performed in vitro, and further confirmed in vivo.

RESULTS

TRPM7 expression is negatively correlated with E-cadherin, but positively with N-cadherin, Vimentin and Twist expression in ovarian cancer samples. TRPM7 depletion inhibited the migration and invasion in SKOV3 and OVCAR3 cells. In addition, TRPM7 silencing decreased the lung metastasis of SKOV3 tumors and prolonged the survival of tumor-bearing mice. Similar to that of TRPM7 silencing, treatment with MK886, a potent 5-lipoxygenase inhibitor to reduce TRPM7 expression, and/or BAPTA-AM, an intracellular calcium chelator, significantly mitigated the Epidermal growth factor (EGF) or Insulin-like growth factors (IGF)-stimulated migration, invasion, and the EMT in ovarian cancer cells by decreasing the levels of intracellular calcium [Ca2+]i. Furthermore, treatment with LY2904002, a PI3K inhibitor, also inhibited the migration, invasion, and treatment with both LY2904002 and BAPTA-AM further enhanced their inhibition in ovarian cancer cells. Moreover, treatment with BAPTA-AM mitigated the IGF-stimulated migration, invasion, particularly in TRPM7-silenced ovarian cancer cells. Finally, TRPM7 silencing attenuated the PI3K/AKT activation, which was enhanced by BAPTA-AM, MK886 or LY2904002 treatment in ovarian cancer cells.

CONCLUSIONS

TRPM7 silencing inhibited the EMT and metastasis of ovarian cancer by attenuating the calcium-related PI3k/AKT activation. Our findings suggest that TRPM7 may be a therapeutic target for intervention of ovarian cancer.

TGF-β1-Induced Airway Smooth Muscle Cell Proliferation Involves TRPM7-Dependent Calcium Influx via TGFβR/SMAD3

BACKGROUND

TRPM7 in mast cells plays a key role in asthma. However, the effect of TRPM7 on TGF-β1-induced airway smooth muscle cell (ASMC) proliferation remains unclear. Therefore, we designed this study to explore whether TRPM7 is involved in TGF-β1-induced ASMC proliferation.

METHODS

An asthmatic mouse model was established, and the expressions of TGF-β1 and TRPM7 in mice lungs were detected using enzyme-linked immunosorbent assay (ELISA) and western blotting. In addition, murine ASMCs were cultured and stimulated with TGF-β1. Possible TGF-β1 and TRPM7 interactions were examined using RT-PCR and western blotting analyses with ASMCs. The effect of TRPM7 knockdown on ASMC calcium influx was assessed by the fluorescent indicator indo-1. MTT and flow cytometry were applied to evaluate the effects of TRPM7 knockdown on ASMC proliferation and apoptosis.

RESULTS

TGF-β1 elevated the expression of TRPM7 via TGFβR/SMAD3. Knocking down TRPM7 decreased the intracellular Ca²⁺ concentration and cellular proliferation of ASMCs, although apoptosis remained unaffected.

CONCLUSIONS

Our initial findings suggest that TRPM7 inhibition may prevent asthma-induced airway remodeling.