Combinatorial treatment with natural compounds leads to smaller prostate tumor size and key modulations of cell metabolism
Authors: Tiziani Stefano , Wang Bo , Saha Achinto , Lu Xiyuan , Sentandreu Enrique , Lodi Alessia , DiGiovanni John 
Published: November 2023

Prostate cancer is one of the three most relevant cancer types in men, ranking second in death rate and first in newly diagnosed cancer cases according to the US cancer statistics in 2015. In recent years, the impact of nutrition on cancer prevention has been increasingly recognized. Accordingly the study of natural compounds for cancer prevention and treatment has drawn attention, mainly for the low toxicity to normal tissues.

In this study, a natural compound library of 140 compounds was screened on prostate cancer cells from the HiMyc mice model (HMVP‐2 cells). Following treatment with the individual library compounds, ATP and reactive oxygen species (ROS) bioluminescence measurements were performed to select the top hit compound. Following the individual screen, the identified top hit compound was screened again in combination with all the library compounds to select a natural compound combinations to be further investigated for the in vivo effect on tumor growth. The effects on cell metabolism of the combination treatments proven effective on tumor growth in vivo were then investigated using a combination of high‐resolution liquid chromatography mass spectrometry (HPLC‐MS) and magnetic resonance spectroscopy (MRS) for large scale untargeted metabolic and lipidomic profiling of intra‐ and extracellular prostate cancer cells.

Based on the individual screen, ursolic acid (UA) was selected as the top hit compound inducing relevant drops in cell growth and a favorable Z‐factor value. UA administered in combination with all the natural compounds led to the selection of curcumin (CUR) as top hit for the combinatorial treatment. We next performed an in vivo study on an allograft mouse model of prostate cancer by injecting HMVP‐2 spheroids into FVB/N mice. After obtaining palpable tumors, we treated the animals with UA and CUR alone and in combination. The individual treatments did not induce a significant improvement on tumor size; however, the combination treatment resulted in smaller tumors than in untreated animals. Moreover both tumor size and weight indicated a synergistic effect (according to the Bliss independence theory method) of the combined agents. The metabolic analysis indicated that the combination of UA and CUR exerts very profound, synergistic effect on cell metabolism of HMVP‐2 cells by altering metabolic pathways associated with alanine, aspartate, proline and glutamate metabolism. Moreover, key intermediates in glycerophospholipid and ceramide metabolism were highly perturbed in CUR+UA indicating a relevant response of lipid metabolism.

In summary, amongst the 140 screened compounds, UA and CUR exerted the most prominent metabolic effects on prostate cancers cells. The combination CUR+UA resulted in synergistic effects on tumor size in vivo and on cell metabolism by significantly affecting key metabolic pathways active in mitochondria, most likely via lipid metabolisms.