The cytotoxicity experiment was done by incubating the cells with different treatments for 48 h. The results show that conjugate 1 is quite similar to free Dox for toxicity to MCF-7 and MDA-MB-435 cancer cells. In contrast, conjugate 2 was ?20 times less cytotoxic to breast cancerous cells compared to free Dox. This could be attributed to the stability of the amide conjugate 2 inside the cells. Furthermore, the cytotoxicity of conjugate 1 in doxorubicin-resistant cell model MDA-MB-435-MDR (IC50 = 5.4 μM) is 4 times more than free Dox (IC50 = 22 μM). In normal cells (HUVEC and MCF-10A) the two conjugates were 3540 times less toxic compared to breast cancer cells, whereas free Dox was equally cytotoxic (equal IC50) to breast cancer cells and noncancerous cells. Overall these results provide clear evidence that of the two conjugates (conjugate 1 and 2), conjugate 1 has optimal characteristics for specific Dox targeting to breast cancer cells.

The cytotoxicity experiment was done by incubating the cells with different treatments for 48 h. The results show that conjugate 1 is quite similar to free Dox for toxicity to MCF-7 and MDA-MB-435 cancer cells. In contrast, conjugate 2 was ?20 times less cytotoxic to breast cancerous cells compared to free Dox. This could be attributed to the stability of the amide conjugate 2 inside the cells. Furthermore, the cytotoxicity of conjugate 1 in doxorubicin-resistant cell model MDA-MB-435-MDR (IC50 = 5.4 μM) is 4 times more than free Dox (IC50 = 22 μM). In normal cells (HUVEC and MCF-10A) the two conjugates were 3540 times less toxic compared to breast cancer cells, whereas free Dox was equally cytotoxic (equal IC50) to breast cancer cells and noncancerous cells. Overall these results provide clear evidence that of the two conjugates (conjugate 1 and 2), conjugate 1 has optimal characteristics for specific Dox targeting to breast cancer cells.

The cytotoxicity experiment was done by incubating the cells with different treatments for 48 h. The results show that conjugate 1 is quite similar to free Dox for toxicity to MCF-7 and MDA-MB-435 cancer cells. In contrast, conjugate 2 was ?20 times less cytotoxic to breast cancerous cells compared to free Dox. This could be attributed to the stability of the amide conjugate 2 inside the cells. Furthermore, the cytotoxicity of conjugate 1 in doxorubicin-resistant cell model MDA-MB-435-MDR (IC50 = 5.4 μM) is 4 times more than free Dox (IC50 = 22 μM). In normal cells (HUVEC and MCF-10A) the two conjugates were 3540 times less toxic compared to breast cancer cells, whereas free Dox was equally cytotoxic (equal IC50) to breast cancer cells and noncancerous cells. Overall these results provide clear evidence that of the two conjugates (conjugate 1 and 2), conjugate 1 has optimal characteristics for specific Dox targeting to breast cancer cells.

The cytotoxicity experiment was done by incubating the cells with different treatments for 48 h. The results show that conjugate 1 is quite similar to free Dox for toxicity to MCF-7 and MDA-MB-435 cancer cells. In contrast, conjugate 2 was ?20 times less cytotoxic to breast cancerous cells compared to free Dox. This could be attributed to the stability of the amide conjugate 2 inside the cells. Furthermore, the cytotoxicity of conjugate 1 in doxorubicin-resistant cell model MDA-MB-435-MDR (IC50 = 5.4 μM) is 4 times more than free Dox (IC50 = 22 μM). In normal cells (HUVEC and MCF-10A) the two conjugates were 3540 times less toxic compared to breast cancer cells, whereas free Dox was equally cytotoxic (equal IC50) to breast cancer cells and noncancerous cells. Overall these results provide clear evidence that of the two conjugates (conjugate 1 and 2), conjugate 1 has optimal characteristics for specific Dox targeting to breast cancer cells.

The cytotoxicity experiment was done by incubating the cells with different treatments for 48 h. The results show that conjugate 1 is quite similar to free Dox for toxicity to MCF-7 and MDA-MB-435 cancer cells. In contrast, conjugate 2 was ?20 times less cytotoxic to breast cancerous cells compared to free Dox. This could be attributed to the stability of the amide conjugate 2 inside the cells. Furthermore, the cytotoxicity of conjugate 1 in doxorubicin-resistant cell model MDA-MB-435-MDR (IC50 = 5.4 μM) is 4 times more than free Dox (IC50 = 22 μM). In normal cells (HUVEC and MCF-10A) the two conjugates were 3540 times less toxic compared to breast cancer cells, whereas free Dox was equally cytotoxic (equal IC50) to breast cancer cells and noncancerous cells. Overall these results provide clear evidence that of the two conjugates (conjugate 1 and 2), conjugate 1 has optimal characteristics for specific Dox targeting to breast cancer cells.

The results showed that the cytotoxicity of both conjugates 1 and 2 (IC50 = 1.3 and 2.2 uM, respectively), as well as the free Dox (IC50 = 1.5 uM) on MDA-MB-231 breast cancer cell line, were in the low micromolar range (Figure 4). For the breast cancer cell line MDA-MB-468, the free Dox (IC50 = 0.35 uM) was slightly more toxic compared to conjugates 1 (4.7 uM) and 2 (1.2 uM). For the non-cancerous cell line MCF 10A, the free Dox was highly toxic (IC50 = 0.24 uM) whereas conjugates 1 and 2 displayed much-reduced toxicity (IC50 = 38.6 and 15.1 uM, respectively).

Several PDCs have been prepared with peptide 18-4 and doxorubicin (Dox) using different linker chemistries such as ester, amide, succinimidyl thioether, or acyl hydrazone. In vitro results showed that these PDCs were highly specific toward breast cancer cells. PDCs displayed similar toxicity as free Dox toward the breast cancer cells and several-fold (7-40 times) less toxicity toward the non-cancerous cells such as MCF-10A and human umbilical vein endothelial cells (HUVECs). A peptide 18-4-Dox conjugate with amide/succinimidyl thioether linkage showed high selective toxicity toward triple negative breast cancer (TNBC) cell lines, i.e., MDA-MB-231 cells (IC50 1.3 ± 0.2 uM) and MDA-MB-468 cells (IC50 4.7 ± 0.3 uM) compared to the normal breast MCF10A cells (IC50 38.6 ± 1.1 uM). The linkage between the drug and the peptide was stable as the degradation half-life of peptide 18-4-Dox conjugate in the presence of human serum was found to be ˜18 h. Herein, we describe the first in vivo evidence for improved efficacy of this PDC targeting K1 receptor in an orthotopic TNBC mouse model. We also show a higher accumulation of PDC in TNBC tumors in mice, in accord with K1 overexpression in tumor over non-tumor tissues in MDA-MB-231 xenografted mice.

The results showed that the cytotoxicity of both conjugates 1 and 2 (IC50 = 1.3 and 2.2 uM, respectively), as well as the free Dox (IC50 = 1.5 uM) on MDA-MB-231 breast cancer cell line, were in the low micromolar range (Figure 4). For the breast cancer cell line MDA-MB-468, the free Dox (IC50 = 0.35 uM) was slightly more toxic compared to conjugates 1 (4.7 uM) and 2 (1.2 uM). For the non-cancerous cell line MCF 10A, the free Dox was highly toxic (IC50 = 0.24 uM) whereas conjugates 1 and 2 displayed much-reduced toxicity (IC50 = 38.6 and 15.1 uM, respectively).

Several PDCs have been prepared with peptide 18-4 and doxorubicin (Dox) using different linker chemistries such as ester, amide, succinimidyl thioether, or acyl hydrazone. In vitro results showed that these PDCs were highly specific toward breast cancer cells. PDCs displayed similar toxicity as free Dox toward the breast cancer cells and several-fold (7-40 times) less toxicity toward the non-cancerous cells such as MCF-10A and human umbilical vein endothelial cells (HUVECs). A peptide 18-4-Dox conjugate with amide/succinimidyl thioether linkage showed high selective toxicity toward triple negative breast cancer (TNBC) cell lines, i.e., MDA-MB-231 cells (IC50 1.3 ± 0.2 uM) and MDA-MB-468 cells (IC50 4.7 ± 0.3 uM) compared to the normal breast MCF10A cells (IC50 38.6 ± 1.1 uM). The linkage between the drug and the peptide was stable as the degradation half-life of peptide 18-4-Dox conjugate in the presence of human serum was found to be ˜18 h. Herein, we describe the first in vivo evidence for improved efficacy of this PDC targeting K1 receptor in an orthotopic TNBC mouse model. We also show a higher accumulation of PDC in TNBC tumors in mice, in accord with K1 overexpression in tumor over non-tumor tissues in MDA-MB-231 xenografted mice.

The results showed that the cytotoxicity of both conjugates 1 and 2 (IC50 = 1.3 and 2.2 uM, respectively), as well as the free Dox (IC50 = 1.5 uM) on MDA-MB-231 breast cancer cell line, were in the low micromolar range (Figure 4). For the breast cancer cell line MDA-MB-468, the free Dox (IC50 = 0.35 uM) was slightly more toxic compared to conjugates 1 (4.7 uM) and 2 (1.2 uM). For the non-cancerous cell line MCF 10A, the free Dox was highly toxic (IC50 = 0.24 uM) whereas conjugates 1 and 2 displayed much-reduced toxicity (IC50 = 38.6 and 15.1 uM, respectively).

Several PDCs have been prepared with peptide 18-4 and doxorubicin (Dox) using different linker chemistries such as ester, amide, succinimidyl thioether, or acyl hydrazone. In vitro results showed that these PDCs were highly specific toward breast cancer cells. PDCs displayed similar toxicity as free Dox toward the breast cancer cells and several-fold (7-40 times) less toxicity toward the non-cancerous cells such as MCF-10A and human umbilical vein endothelial cells (HUVECs). A peptide 18-4-Dox conjugate with amide/succinimidyl thioether linkage showed high selective toxicity toward triple negative breast cancer (TNBC) cell lines, i.e., MDA-MB-231 cells (IC50 1.3 ± 0.2 uM) and MDA-MB-468 cells (IC50 4.7 ± 0.3 uM) compared to the normal breast MCF10A cells (IC50 38.6 ± 1.1 uM). The linkage between the drug and the peptide was stable as the degradation half-life of peptide 18-4-Dox conjugate in the presence of human serum was found to be ˜18 h. Herein, we describe the first in vivo evidence for improved efficacy of this PDC targeting K1 receptor in an orthotopic TNBC mouse model. We also show a higher accumulation of PDC in TNBC tumors in mice, in accord with K1 overexpression in tumor over non-tumor tissues in MDA-MB-231 xenografted mice.

The cytotoxicity experiment was done by incubating the cells with different treatments for 48 h. The results show that conjugate 1 is quite similar to free Dox for toxicity to MCF-7 and MDA-MB-435 cancer cells. In contrast, conjugate 2 was ?20 times less cytotoxic to breast cancerous cells compared to free Dox. This could be attributed to the stability of the amide conjugate 2 inside the cells. Furthermore, the cytotoxicity of conjugate 1 in doxorubicin-resistant cell model MDA-MB-435-MDR (IC50 = 5.4 μM) is 4 times more than free Dox (IC50 = 22 μM). In normal cells (HUVEC and MCF-10A) the two conjugates were 3540 times less toxic compared to breast cancer cells, whereas free Dox was equally cytotoxic (equal IC50) to breast cancer cells and noncancerous cells. Overall these results provide clear evidence that of the two conjugates (conjugate 1 and 2), conjugate 1 has optimal characteristics for specific Dox targeting to breast cancer cells.

The cytotoxicity experiment was done by incubating the cells with different treatments for 48 h. The results show that conjugate 1 is quite similar to free Dox for toxicity to MCF-7 and MDA-MB-435 cancer cells. In contrast, conjugate 2 was ?20 times less cytotoxic to breast cancerous cells compared to free Dox. This could be attributed to the stability of the amide conjugate 2 inside the cells. Furthermore, the cytotoxicity of conjugate 1 in doxorubicin-resistant cell model MDA-MB-435-MDR (IC50 = 5.4 μM) is 4 times more than free Dox (IC50 = 22 μM). In normal cells (HUVEC and MCF-10A) the two conjugates were 3540 times less toxic compared to breast cancer cells, whereas free Dox was equally cytotoxic (equal IC50) to breast cancer cells and noncancerous cells. Overall these results provide clear evidence that of the two conjugates (conjugate 1 and 2), conjugate 1 has optimal characteristics for specific Dox targeting to breast cancer cells.

The cytotoxicity experiment was done by incubating the cells with different treatments for 48 h. The results show that conjugate 1 is quite similar to free Dox for toxicity to MCF-7 and MDA-MB-435 cancer cells. In contrast, conjugate 2 was ?20 times less cytotoxic to breast cancerous cells compared to free Dox. This could be attributed to the stability of the amide conjugate 2 inside the cells. Furthermore, the cytotoxicity of conjugate 1 in doxorubicin-resistant cell model MDA-MB-435-MDR (IC50 = 5.4 μM) is 4 times more than free Dox (IC50 = 22 μM). In normal cells (HUVEC and MCF-10A) the two conjugates were 3540 times less toxic compared to breast cancer cells, whereas free Dox was equally cytotoxic (equal IC50) to breast cancer cells and noncancerous cells. Overall these results provide clear evidence that of the two conjugates (conjugate 1 and 2), conjugate 1 has optimal characteristics for specific Dox targeting to breast cancer cells.

The cytotoxicity experiment was done by incubating the cells with different treatments for 48 h. The results show that conjugate 1 is quite similar to free Dox for toxicity to MCF-7 and MDA-MB-435 cancer cells. In contrast, conjugate 2 was ?20 times less cytotoxic to breast cancerous cells compared to free Dox. This could be attributed to the stability of the amide conjugate 2 inside the cells. Furthermore, the cytotoxicity of conjugate 1 in doxorubicin-resistant cell model MDA-MB-435-MDR (IC50 = 5.4 μM) is 4 times more than free Dox (IC50 = 22 μM). In normal cells (HUVEC and MCF-10A) the two conjugates were 3540 times less toxic compared to breast cancer cells, whereas free Dox was equally cytotoxic (equal IC50) to breast cancer cells and noncancerous cells. Overall these results provide clear evidence that of the two conjugates (conjugate 1 and 2), conjugate 1 has optimal characteristics for specific Dox targeting to breast cancer cells.

The cytotoxicity experiment was done by incubating the cells with different treatments for 48 h. The results show that conjugate 1 is quite similar to free Dox for toxicity to MCF-7 and MDA-MB-435 cancer cells. In contrast, conjugate 2 was ?20 times less cytotoxic to breast cancerous cells compared to free Dox. This could be attributed to the stability of the amide conjugate 2 inside the cells. Furthermore, the cytotoxicity of conjugate 1 in doxorubicin-resistant cell model MDA-MB-435-MDR (IC50 = 5.4 μM) is 4 times more than free Dox (IC50 = 22 μM). In normal cells (HUVEC and MCF-10A) the two conjugates were 3540 times less toxic compared to breast cancer cells, whereas free Dox was equally cytotoxic (equal IC50) to breast cancer cells and noncancerous cells. Overall these results provide clear evidence that of the two conjugates (conjugate 1 and 2), conjugate 1 has optimal characteristics for specific Dox targeting to breast cancer cells.

The internalization of nanoparticles in cancer cells is the foremost step in PDT. Targeting ligand decoration and reducing nanoparticle size have been intensively explored to enhance the intracellular uptake of nanoparticles. Therefore, the PPC nanoparticles were designed to offer the appropriate size and targeting ability for delivery of Ce6 to tumor tissues via active and passive targeting mechanisms. The cellular internalization of free Ce6 and PPC into various cancer cells, i.e., MDA-MB-231, MKN-28, and HeLa, was assessed by fluorescence-activated cell sorting (FACS) analysis using a flow cytometer. When compared with free Ce6, the higher cellular internalization of PPC was observed in all cancer cells tested. In particular, the fluorescence intensity due to the intracellular uptake of PPC in MDA-MB-231 cells increased more dramatically than in the other cancer cells.