Rvival in PDAC, BxPC3, HPAF-II, and PANC1 cell lines were treated with gemcitabine or vehicle for 72 hours and assessed for cell viability by propidium iodide (PI) exclusion. Knocking-down LCN2 in the BxPC3 and HPAF-II cell lines significantly increased the number of PI-positive cells indicating cell death, while LCN2 overexpression in PANC1 cells conferred increased resistance to gemcitabine (p,0.05, 
Fig. 3G). Immunoblot analysis of cleaved caspase-3 validated the flow cytometry results. Depleting LCN2 expression increased caspase-3 cleavage by two-fold in gemcitabine treated BxPC3 and HPAF-II cell lines, while LCN2 expression in PANC1 reversed this effect (Fig. 3H). No significant differences in the expression of antiapoptotic proteins Bcl-xL and Bcl-2, and pro-apoptotic proteins Bad, Bax, and Bim were observed after altering LCN2 expression. The half maximal inhibitory concentrations (IC50) of gemcitabine dependence on LCN2 were investigated. The IC50 concentrations of the control BxPC3, HPAF-II, and PANC1 were 10 mM, 50 mM, and 20 mM, respectively. 69-25-0 Knocking down LCN2 in the BxPC3 and HPAF-II cell lines reduced the IC50 concentrations to 5 mM and 20 mM, respectively. Whereas, expression of LCN2 in PANC1 increased the IC50 to 50 mM of gemcitabine (n = 5; Fig. S1F ).LCN2 Promotes Gemcitabine Insensitivity in Resistant PDAC Cells in vivoSince LCN2 has been demonstrated to promote survival in PDAC and several cancer cell line models in vitro, we wanted to determine if LCN2 would have an effect on gemcitabine sensitivity of PDAC in vivo [10,17]. Tumor bearing mice were treated with vehicle (PBS) or 100 mg/kg gemcitabine once every seven days. BxPC3 is inherently insensitive to gemcitabine, whereas PANC1 is sensitive in vivo [24]. Gemcitabine treated BxPC3 NS mice showed no change in tumor growth compared to the vehicle treated mice. Attenuating LCN2 expression in BxPC3 cells reduced tumor growth (p,0.0001) and increased sensitivity to gemcitabine (p = 0.0003; Fig. 6A; Table S3). In PANC1 cells, LCN2 expression enhanced tumor growth (p = 0.00035; Fig. 6B), but was not correlated with increased resistance as gemcitabine (p,0.00001). Knocking down LCN2 in BxPC3 xenografts had increased cleaved caspase-3 activity by over 5-fold after treatment with gemcitabine compared mice bearing control xenografts (Fig. 6C, S2B; p,0.0001). Whereas, expressing LCN2 in the PANC1 xenografts reduced cleaved caspase-3 activity by 30 (p = 0.035). Assessment of LCN2 immunostaining PTH 1-34 revealed that the BxPC3 xenografts maintained the expression of the shRNA targeted against LCN2, and the PANC-1 xenografts retained expression of the LCN2 construct (Fig. 6D). Furthermore, Ki67 immunostaining did not demonstrate 
any differences in proliferation between high and low LCN2 expressing xenografts. Thus, LCN2 promotes gemcitabine resistance in insensitive lines. LCN2 promotes angiogenesis. HIF1A was identified as one of the significantly upregulated genes in the microarray analysis which prompted us to assess the vascularity and VEGF expression in the BxPC3 and PANC1 xenografts [25]. The quantification of CD31 positive blood vessels revealed that knocking-down LCN2 in BxPC3 cells decreased expression of HIF1A and VEGF, and vascularity by 15 (Fig. 6E ). Whereas expressing LCN2 in PANC1 cells increased vascularity by 11 and elevated expression of these angiogenic genes in vivo (p,0.05). We conclude that LCN2 promotes tumor growth, invasion, angiogenesis, and maintains resist.Rvival in PDAC, BxPC3, HPAF-II, and PANC1 cell lines were treated with gemcitabine or vehicle for 72 hours and assessed for cell viability by propidium iodide (PI) exclusion. Knocking-down LCN2 in the BxPC3 and HPAF-II cell lines significantly increased the number of PI-positive cells indicating cell death, while LCN2 overexpression in PANC1 cells conferred increased resistance to gemcitabine (p,0.05, Fig. 3G). Immunoblot analysis of cleaved caspase-3 validated the flow cytometry results. Depleting LCN2 expression increased caspase-3 cleavage by two-fold in gemcitabine treated BxPC3 and HPAF-II cell lines, while LCN2 expression in PANC1 reversed this effect (Fig. 3H). No significant differences in the expression of antiapoptotic proteins Bcl-xL and Bcl-2, and pro-apoptotic proteins Bad, Bax, and Bim were observed after altering LCN2 expression. The half maximal inhibitory concentrations (IC50) of gemcitabine dependence on LCN2 were investigated. The IC50 concentrations of the control BxPC3, HPAF-II, and PANC1 were 10 mM, 50 mM, and 20 mM, respectively. Knocking down LCN2 in the BxPC3 and HPAF-II cell lines reduced the IC50 concentrations to 5 mM and 20 mM, respectively. Whereas, expression of LCN2 in PANC1 increased the IC50 to 50 mM of gemcitabine (n = 5; Fig. S1F ).LCN2 Promotes Gemcitabine Insensitivity in Resistant PDAC Cells in vivoSince LCN2 has been demonstrated to promote survival in PDAC and several cancer cell line models in vitro, we wanted to determine if LCN2 would have an effect on gemcitabine sensitivity of PDAC in vivo [10,17]. Tumor bearing mice were treated with vehicle (PBS) or 100 mg/kg gemcitabine once every seven days. BxPC3 is inherently insensitive to gemcitabine, whereas PANC1 is sensitive in vivo [24]. Gemcitabine treated BxPC3 NS mice showed no change in tumor growth compared to the vehicle treated mice. Attenuating LCN2 expression in BxPC3 cells reduced tumor growth (p,0.0001) and increased sensitivity to gemcitabine (p = 0.0003; Fig. 6A; Table S3). In PANC1 cells, LCN2 expression enhanced tumor growth (p = 0.00035; Fig. 6B), but was not correlated with increased resistance as gemcitabine (p,0.00001). Knocking down LCN2 in BxPC3 xenografts had increased cleaved caspase-3 activity by over 5-fold after treatment with gemcitabine compared mice bearing control xenografts (Fig. 6C, S2B; p,0.0001). Whereas, expressing LCN2 in the PANC1 xenografts reduced cleaved caspase-3 activity by 30 (p = 0.035). Assessment of LCN2 immunostaining revealed that the BxPC3 xenografts maintained the expression of the shRNA targeted against LCN2, and the PANC-1 xenografts retained expression of the LCN2 construct (Fig. 6D). Furthermore, Ki67 immunostaining did not demonstrate any differences in proliferation between high and low LCN2 expressing xenografts. Thus, LCN2 promotes gemcitabine resistance in insensitive lines. LCN2 promotes angiogenesis. HIF1A was identified as one of the significantly upregulated genes in the microarray analysis which prompted us to assess the vascularity and VEGF expression in the BxPC3 and PANC1 xenografts [25]. The quantification of CD31 positive blood vessels revealed that knocking-down LCN2 in BxPC3 cells decreased expression of HIF1A and VEGF, and vascularity by 15 (Fig. 6E ). Whereas expressing LCN2 in PANC1 cells increased vascularity by 11 and elevated expression of these angiogenic genes in vivo (p,0.05). We conclude that LCN2 promotes tumor growth, invasion, angiogenesis, and maintains resist.