Fig. 5

Expression and tumor-suppressive functions of LRIG1 in CRPC. a Heterogeneous LRIG1 expression and discordant AR/LRIG1 expression patterns in CRPC. Contiguous WM sections from a CRPC (case# indicated on left) were stained for (top) AR (mouse mAb from Santa Cruz clone 441; 1:100 dilution)) and (bottom) LRIG1 (Sigma, 1:100 dilution). AR^+/hi/LRIG1^hi, AR^−/lo/LRIG1^lo, and AR^−/lo/LRIG1^hi areas are marked by solid red, solid black, and dashed black circles, respectively (note that the AR IHC image represented part of the image in Fig. 1c of ref. ⁵¹). b Experimental scheme to generate castration-resistant (androgen-independent [AI]) xenograft tumors from the corresponding androgen-dependent (AD; androgen-sensitive) parent tumors (see Methods). c, d Reduced but persistent LRIG1 expression in experimental CRPC. Whole lysate of AD and AI tumors at the indicated passages (P) was used in WB for molecules indicated. The asterick in c represents a non-specific band detected by Sigma anti-LRIG1 antibody. e, f Reduced LRIG1 mRNA levels in LAPC9 (e) and LNCaP (f) AI tumors. Presented are the raw read counts of LRIG1 mRNA fragments in RNA-seq of AD/AI tumors (n = 5 each; ref. ⁵¹). For the LNCaP model, a condition of “AI + DHT” was added. *P < 0.05; **P < 0.01 (unpaired multiple t-test in GraphPad and statistical significance determined using the Holm-Sidak method). The centerlines in box plots e show the mean values, box edges are 25th and 75th percentiles and whiskers represent minimum and maximum values. g LRIG1 overexpression in LNCaP AI cells inhibits CRPC regeneration. LNCaP cells were freshly purified out from AI tumors and infected with control (CTL) or pLVX-LRIG1 (LRIG1) lentiviral vectors (MOI 5, 48 h), and subcutaneously (s.c) injected in castrated NSG mice. Tumor incidence, tumor weight, and P values are indicated. h Knocking down endogenous LRIG1 in LAPC9 AI cells promotes CRPC regeneration. LAPC9 AI cells were purified out from xenografts and infected with control (NS) or shLRIG1 vectors (MOI 10, 12 h), and s.c injected (at two cell doses) in castrated male NOD/SCID mice. Tumor incidence, TIF (tumor-initiating frequency), tumor weight, and P values are indicated. *Source data for Fig. 5c, d, g, h are provided as a Source Data file.