LDM chemotherapy attenuates the treatment-induced expressions of ELR⁺ chemokines in CAFs. (A) Schematic showing doxorubicin treatment protocols that mimic MTD and LDM chemotherapy regimens. (B) The transcript levels of the ELR⁺ chemokines CXCL1, CXCL2, CXCL5, and CXCL6 in vehicle, MTD-doxorubicin–, or LDM-doxorubicin–treated BCAF-011 or BC-008 CAFs 14 d after initiation of the treatments. Data from two independent experiments (n = 3 in each group) are shown. (C) Schematic showing paclitaxel treatment protocols that mimic MTD (650 nM × 24 h) and LDM (65 nM daily × 10 d) chemotherapy regimens (n = 3 in each group). (D) The transcript levels of the ELR⁺ chemokines in vehicle-, MTD-paclitaxel–, or LDM-paclitaxel–treated BCAF-011 CAFs 14 d after initiation of the treatments. Data from three independent experiments (n = 3 in each group) are shown. (E) Schematic showing 4H-CPA treatment protocols that mimic MTD (150 nM × 1 h) and LDM (15 nM × 1 h daily for 10 d) chemotherapy regimens. (F) The transcript levels of the ELR⁺ chemokines in vehicle, MTD–4H-CPA–, or LDM–4H-CPA–treated BCAF-011 CAFs 14 d after initiation of the treatments. Data from three independent experiments (n = 3 in each group) are shown. (G) Schematic showing doxorubicin treatment protocols that recapitulate MTD (50 nM X 96 h)- or different LDM-mimetic regimens with gradually prolonged lengths of drug exposure (from LDM-R1 to LDM-R4). Note that the total accumulated doses of drug exposure, as reflected in area under curves, were the same across all the treatment groups (4,800 nM × h). (A, C, E, and G) Arrows indicate time of drug clearance by wash. (H) Fold-increases in the transcript levels of the ELR⁺-chemokines in BCAF-011 CAFs exposed to vehicle or doxorubicin using the treatment protocols described in G. Data from three independent experiments (n = 3 in each group) are shown. (I) BCAF-011 CAFs were lentivirally infected with GFP and then co-injected with BC-011 carcinoma cells into the mammary fat pads of NOG mice. 2 wk after cell inoculation, the tumors were given injections of vehicle or doxorubicin at an MTD (2 mg/kg as a single-dose intravenous injection)- or an LDM (0.2 mg/kg every day by intraperitoneal injections for 10 consecutive days)-mimetic therapy regimen and then removed for cell dissociation followed by transcript analyses. (J) The transcript levels of the ELR⁺ chemokines in the GFP⁺ CAFs isolated from the tumors in I. Data from one experiment (n = 5 in each group) are shown. (K) BCAF-011 CAFs were co-inoculated with GFP-transduced BC-011 carcinoma cells into the mammary fat pads of NOG mice. The resultant tumors were given injections of vehicle or doxorubicin at a MTD- or a LDM-mimetic regimen as described in I. The tumors were then removed for cell dissociation followed by flow cytometric analyses. (L) The percentages of GFP⁺CD44⁺CD24^−/low cells relative to the GFP⁺ carcinoma cells isolated from the tumors described in K. Data from one experiment (n = 5 in each group) are shown. Data are mean ± SEM; Student’s t test. *, P < 0.05; **, P < 0.01 versus vehicle. †, P < 0.05 versus MTD.