Emilio Guillén-Mancina

Selenium, zinc, copper, and manganese are essential components of antioxidant enzymes involved in the elimination of reactive oxygen species (ROS). Given that cancer cells produce high levels of ROS and the accumulation of ROS can lead to cell death, cancer cells may be susceptible to strategies that reduce ROS elimination. In this work, we prepared several artificial diets that contained normal carbohydrate, protein, and lipid levels but lacked selenium, zinc, copper, or manganese. The anticancer activity of these diets was examined in a metastatic ovarian cancer model, established by injecting ID8 Trp53^−/− murine ovarian cancer cells into the peritoneal cavity of C57BL/6JRj mice. Treatments started 15 days later and consisted of replacing a normal diet with one of the artificial diets for several weeks. A significant improvement in mice survival was observed when the normal diet was replaced with the selenium-free diet. Diets lacking zinc, copper, or manganese showed no significant impact on mice survival. All diets were very well tolerated. The anticancer efficacy of a diet lacking selenium was confirmed in mice with metastatic colon cancer and in mice with metastatic triple-negative breast cancer. These results suggest that diets lacking selenium hold potential for the treatment of metastatic cancers.

Breast cancer is the most common type of cancer in women. Although current treatments can increase patient survival, they are rarely curative when the disease is advanced (metastasis). Therefore, there is an urgent need to develop new cytotoxic drugs with a high selectivity toward cancer cells. Since repurposing approved drugs for cancer therapy has been a successful strategy in recent years, in this study, we screened a library of antiviral piperazine-derived compounds as anticancer agents. The compounds included a piperazine ring and aryl urea functions, which are privileged structures present in several anti-breast cancer drugs. The selective cytotoxic activity of a set of thirty-four 4-acyl-2-substituted piperazine urea derivatives against MCF7 breast cancer cells and MCF 10A normal breast cells was determined. Compounds 31, 32, 35, and 37 showed high selective anticancer activity against breast cancer cells and were also tested against another common type of cancer, non-small cell lung cancer (A549 lung cancer cells versus MRC-5 lung normal cells). Compounds 35 and 37 also showed selectivity against lung cancer cells. These results suggest that compounds 35 and 37 may be promising hit compounds for the development of new anticancer agents.

Patients with metastatic triple negative breast cancer (TNBC) need new therapies to improve the low survival rates achieved with standard treatments. In this work, we show for the first time that the survival of mice with metastatic TNBC can be markedly increased by replacing their normal diet with artificial diets in which the levels of amino acids (AAs) and lipids are strongly manipulated. After observing selective anticancer activity in vitro, we prepared five artificial diets and evaluated their anticancer activity in a challenging model of metastatic TNBC. The model was established by injecting 4T1 murine TNBC cells into the tail vein of immunocompetent BALB/cAnNRj mice. First-line drugs doxorubicin and capecitabine were also tested in this model. AA manipulation led to modest improvements in mice survival when the levels of lipids were normal. Reducing lipid levels to 1% markedly improved the activity of several diets with different AA content. Some mice fed the artificial diets as monotherapy lived much longer than mice treated with doxorubicin and capecitabine. An artificial diet without 10 non-essential AAs, with reduced levels of essential AAs, and with 1% lipids improved the survival not only of mice with TNBC but also of mice with other types of metastatic cancers.

Sulfur-containing amino acids methionine (Met), cysteine (Cys) and taurine (Tau) are common dietary constituents with important cellular roles. Met restriction is already known to exert in vivo anticancer activity. However, since Met is a precursor of Cys and Cys produces Tau, the role of Cys and Tau in the anticancer activity of Met-restricted diets is poorly understood. In this work, we screened the in vivo anticancer activity of several Met-deficient artificial diets supplemented with Cys, Tau or both. Diet B1 (6% casein, 2.5% leucine, 0.2% Cys and 1% lipids) and diet B2B (6% casein, 5% glutamine, 2.5% leucine, 0.2% Tau and 1% lipids) showed the highest activity and were selected for further studies. Both diets induced marked anticancer activity in two animal models of metastatic colon cancer, which were established by injecting CT26.WT murine colon cancer cells in the tail vein or peritoneum of immunocompetent BALB/cAnNRj mice. Diets B1 and B2B also increased survival of mice with disseminated ovarian cancer (intraperitoneal ID8 Tp53^−/− cells in C57BL/6JRj mice) and renal cell carcinoma (intraperitoneal Renca cells in BALB/cAnNRj mice). The high activity of diet B1 in mice with metastatic colon cancer may be useful in colon cancer therapy.

The sulfur-containing amino acids methionine (Met), cysteine (Cys) and taurine (Tau) are common dietary constituents with important cellular roles. Met restriction is already known to exert in vivo anticancer activity. However, since Met is a precursor of Cys, and Cys produces Tau, the role of Cys and Tau in the anticancer activity of Met-restricted diets is poorly understood. In this work, we screened the in vivo anticancer activity of several Met-deficient artificial diets supplemented with Cys, Tau or both. Diet B1 (6% casein, 2.5% leucine, 0.2% Cys and 1% lipids) and diet B2B (6% casein, 5% glutamine, 2.5% leucine, 0.2% Tau and 1% lipids) showed the highest activity and were selected for further studies. Both diets induced a marked anticancer activity in two animal models of metastatic colon cancer, which were established by injecting CT26.WT murine colon cancer cells in the tail vein or peritoneum of immunocompetent BALB/cAnNRj mice. Diets B1 and B2B also increased the survival of mice with disseminated ovarian cancer (intraperitoneal ID8 Tp53 -/- cells in C57BL/6JRj mice) and renal cell carcinoma (intraperitoneal Renca cells in BALB/cAnNRj mice). The high activity of diet B1 in mice with metastatic colon cancer may be useful in colon cancer therapy.

Patients with metastatic triple negative breast cancer (TNBC) need new therapies to improve the low survival rates achieved with standard treatments. In this work, we show that the survival of mice with metastatic TNBC can be markedly increased by replacing their normal diet with artificial diets in which the levels of amino acids (AAs) and lipids are strongly manipulated. After observing selective anticancer activity in vitro, we prepared five artificial diets and evaluated their anticancer activity in a challenging model of metastatic TNBC. The model was established by injecting 4T1 murine TNBC cells into the tail vein of immunocompetent BALB/cAnNRj mice. First-line drugs doxorubicin and capecitabine were used as positive controls. AA manipulation led to modest improvements in mice survival when the levels or lipids were normal. Reducing lipid levels to 1% markedly improved the activity of several diets with different AA content. Mice fed the artificial diets as monotherapy lived longer than mice treated with doxorubicin and capecitabine. An artificial diet without 10 non-essential AAs, with reduced levels of essential AAs, and with 1% lipids improved the survival not only of mice with TNBC but also of mice with other types of metastatic cancers.

Targeted therapies with antiangiogenic drugs (e.g., sunitinib) and immune checkpoint inhibitors (e.g., anti-PD-1 antibodies) are the standard of care for patients with metastatic renal cell carcinoma. Although these treatments improve patient survival, they are rarely curative. We previously hypothesized that advanced cancers might be treated without drugs by using artificial diets in which the levels of specific amino acids (AAs) are manipulated. In this work, after showing that AA manipulation induces selective anticancer activity in renal cell carcinoma cells in vitro, we screened 18 artificial diets for anticancer activity in a challenging animal model of renal cell carcinoma. The model was established by injecting murine renal cell carcinoma (Renca) cells into the peritoneum of immunocompetent BALB/cAnNRj mice. Mice survival was markedly improved when their normal diet was replaced with our artificial diets. Mice fed a diet lacking six AAs (diet T2) lived longer than mice treated with sunitinib or anti-PD-1 immunotherapy; several animals lived very long or were cured. Controlling the levels of several AAs (e.g., cysteine, methionine, and leucine) and lipids was important for the anticancer activity of the diets. Additional studies are needed to further evaluate the therapeutic potential and mechanism of action of this simple and inexpensive anticancer strategy.

New therapies are needed to improve the low survival rates of patients with metastatic colon cancer. Evidence suggests that amino acid (AA) restriction can be used to target the altered metabolism of cancer cells. In this work, we evaluated the therapeutic potential of selective AA restriction in colon cancer. After observing anticancer activity in vitro, we prepared several artificial diets and evaluated their anticancer activity in two challenging animal models of metastatic colon cancer. These models were established by injecting CT26.WT murine colon cancer cells in the peritoneum (peritoneal dissemination) or in the tail vein (pulmonary metastases) of immunocompetent BALB/cAnNRj mice. Capecitabine, which is a first-line treatment for patients with metastatic colon cancer, was also evaluated in these models. Mice fed diet TC1 (a diet lacking 10 AAs) and diet TC5 (a diet with 6% casein, 5% glutamine, and 2.5% leucine) lived longer than untreated mice in both models; several mice survived the treatment. Diet TC5 was better than several cycles of capecitabine in both cancer models. Cysteine supplementation blocked the activity of diets TC1 and TC5, but cysteine restriction was not sufficient for activity. Our results indicated that artificial diets based on selective AA restriction have therapeutic potential for colon cancer.

Targeted therapies with antiangiogenic drugs (e.g., sunitinib) and immune checkpoint inhibitors (e.g., anti-PD-1 antibodies) are the standard of care for patients with metastatic renal cell carcinoma. Although these treatments improve patient survival, they are rarely curative. We previously hypothesized that advanced cancers might be treated without drugs by using artificial diets in which the levels of specific amino acids (AAs) are manipulated. In this work, after showing that AA manipulation induces selective anticancer activity in renal cell carcinoma cells in vitro, we evaluated the anticancer activity of 17 artificial diets in a challenging animal model of renal cell carcinoma. The model was stablished by injecting murine renal cell carcinoma (Renca) cells into the peritoneum of immunocompetent BALB/cAnNRj mice. Mice survival was markedly improved when their normal diet was replaced with our artificial diets. Mice fed a diet lacking six AAs (diet T2) lived longer than mice treated with sunitinib or anti-PD-1 immunotherapy; several animals lived very long or were cured. Controlling the levels of several AAs (e.g., cysteine, methionine and leucine) and lipids was important for the anticancer activity of the diets. Additional studies are needed to further evaluate the therapeutic potential of this simple and inexpensive anticancer strategy.

Finding cytotoxic drugs with a high selectivity towards cancer cells is crucial to improve the low survival rates of patients diagnosed with metastatic cancers. Since plants are an important source of anticancer drugs, we have screened 65 extracts from 45 plants collected in several areas of Western Andalusia (Spain) for cytotoxic activity on lung cancer cells versus lung normal cells. An extract from the leaves of Tetraclinis articulata (Vahl) Mast. (Cupressaceae) showed a marked cytotoxicity (IC50 = 0.37 ± 0.03 μg/mL) and selectivity (selectivity index = 378.3) against the lung cancer cells; cisplatin, 5-fluorouracil, and an extract from the leaves of Taxus baccata L. (Taxaceae) were less cytotoxic and selective. Extracts from Cascabela thevetia (L.) Lippold (Apocynaceae), Frangula alnus Mill. (Rhamnaceae), Iberis ciliata subsp. contracta (Pers.) Moreno (Brassicaceae), Juniperus macrocarpa Sm (Cupressaceae), and Pancratium maritimum L. (Amaryllidaceae) also showed selective cytotoxicity (selectivity index > 10). Active extracts were also tested against a panel of cancer cell lines from a variety tissues. The plants identified in this work are potential sources of natural compounds with selective toxicity towards cancer cells.