Classical cadherins can be further subdivided into the type I classical cadherins consisting of CDH1 (E-cad), CDH2 (N-cad), CDH3 (P-cad), CDH4 (R-cad), and CDH15 (M-cad); the type II classical cadherins include CDH5 (VE-cad), CDH6
(K-cad), CDH7, CDH8, CDH9 (T1-cad), CDH10 (T2-cad), CDH11 (OB-cad), CDH12 (N-cad-2), CDH18, CDH19, CDH20, CDH22, and CDH24.
Data from animal models suggest that emigrating NCCs upregulate CDH7 (in birds), CDH6
(in mouse), and CDH11 (in mouse and Xenopus) (Kimura et al., 1995; Nakagawa and Takeichi, 1995, 1998; Inoue et al., 1997; Vallin et al., 1998; Strobl-Mazzulla and Bronner, 2012; McKeown et al., 2013).
All CDH genes (n = 27) screened in this study include CDH1 (E-cadherin), CDH2 (N-cadherin), CDH3 (P-cadherin), CDH4 (R-cadherin), CDH5 (VE-cadherin), CDH6 (K-cadherin), CDH7 (cadherin 7), CDH8 (cadherin 8), CDH9 (T1-cadherin), CDH10 (T2-cadherin), CDH11 (OB-cadherin), CDH12 (N-cadherin 2), CDH13 (H-cadherin), CDH15 (M-cadherin), CDH16 (KSP-cadherin), CDH17 (LI-cadherin), CDH18 (cadherin 18), CDH20 (cadherin 20), PCDHGA12 (CDH21), CDH22 CDH23 CDH24 DCHS1 (CDH19, or CDH25), CDH26 DCHS2 (CDH27), CDHR3 (CDH28), and CDHR4 (CDH29).
In TNBC, CDH1, CDH2, CDH4, CDH6, CDH17, and CDH26 also exhibited marked alterations (Figure 1(a), Supplementary Figure S2).
As for CDH4, CDH6, and CDH17, although there was rare emerging evidence to demonstrate their possible direct roles in the CSCs, a few reports demonstrated their functional roles in epithelial structure and even in regulation of EMT-like activity [57-60].
Genes with gradually increasing expression and higher passages included CXCL12, CDH6
, and FOLR3.
E-cadherin and cytokeratin 18 (CK18) are markers of mature epithelial cells; K- cadherin (CDH6) is an early marker of epithelial commitment of nephron progenitors; aquaporin 1 (Aqp1) and osteopontin (OPN) are a marker of renal tubule epithelia cells [23-26].
The RNA levels of SIX-2, Wnt4, LEF1, Axin2, PKG1, Glut1, CDH6, Aqp1, and OPN were detected with a SYBR-Green RTqPCR kit (Takara, Japan) according to the manufacturer's instructions (Sangon Biotech, China).
The RNA levels of CDH6, Aqp1, and OPN were also increased by hypoxic culture (Figures 5(f)-5(h)).
This result was confirmed by reduced expressions of E-cadherin, CDH6, Aqp1, and OPN detected by western blotting or PCR (Figures 5(e)-5(h)), which suggested that activation of the Wnt/[beta]-catenin pathway abrogated the differentiation of MMSCs induced by hypoxia.
(f)-(h) Expression of CDH6, Aqp1, and OPN was detected by qRT-PCR; the result was consistent with that of E-cadherin; * p < 0.05; ** p < 0.01; n = 3.