**2.3. Transient receptor potential channels in breast cancer**

Transient receptor potential (TRP) channels have been documented to play an important role in the development and progression of cancer. TRPC1, TRPC6, TRPM7, TRPM8, and TRPV6 channels were described to be upregulated in human breast ductal adenocarcinoma in comparison with the adjacent nontumoral tissue, and correlations with the proliferative parameters or the invasiveness cell capacity have been evidenced [84]. Moreover, several studies documented the role of TRP channels in different breast cancer cell lines. In detail, TRPM7 was demonstrated by silencing experiments to contribute to the migration and invasiveness of MDA-MB-435 breast cancer cells by signaling through the MAPK, but not through Akt, pathway [85]. TRPM8 was detected in BT-474 and MDA-MB-231, but not in MCF7, breast carcinoma cells, while mentholevoked Ca2+-oscillations were recorded in all three breast cancer cell lines [86]. TRPV6 had a high level of expression in breast adenocarcinoma tissue [87]. TRPV1 is functionally expressed in SUM149PT breast cancer cells, a model for a very aggressive form of breast cancer (i.e., triplenegative breast cancer) [88], and in MCF7 breast cancer cells [89, 90].
