Rice bran nanoparticles show promise as targeted cancer therapy

Bowl of rice bran

Researchers have discovered that nanoparticles derived from rice bran are both effective and safe for the treatment of cancer.

Cancer therapies that employ nanoparticles can specifically target cancer cells, sparing healthy tissue.

Recent studies have demonstrated that plant-derived nanoparticles (pdNPs) that have therapeutic effects can be an effective alternative to traditional cancer treatments. However, no pdNPs have been approved as anticancer therapeutic agents to date.

Rice bran is a byproduct generated during rice refining processes that has limited utility and low commercial value. However, it contains several compounds with anticancer properties, such as γ-oryzanol and γ-tocotrienol.

A team of researchers led by Professor Makiya Nishikawa from Tokyo University of Science (TUS) in Japan developed nanoparticles from rice bran and tested their effectiveness in mice models.

“In recent years, an increasing number of new drug modalities are being developed. At the same time, development costs associated with novel therapies have increased dramatically, contributing to the burden of medical expenses. To address this issue, we used rice bran, an industrial waste with anticancer properties, to develop nanoparticles,” explains Professor Nishikawa.

High anticancer activity

The study evaluated the anticancer effects of rice bran-derived nanoparticles (rbNPs), which were obtained by processing and purifying a suspension of Koshihikari rice bran in water.

When a cancer cell line named colon26 was treated with rbNPs, cell division was arrested and programmed cell death was induced, indicating strong anticancer effects of the nanoparticles.

The observed anticancer activity of rbNPs can be attributed to γ-tocotrienol and γ-oryzanol, that are easily taken up by cancer cells resulting in cell cycle arrest and programmed cell death.

Additionally, rbNPs reduced the expression of proteins, such as β-catenin (a protein associated with Wnt signaling pathway involved in cell proliferation) and cyclin D1, which are known to promote cancer recurrence and metastases. Moreover, the rbNPs reduced the expression of β-catenin only in colon26 cells without affecting the non-cancerous cells.

“A key concern in the context of pdNPs is their low pharmacological activity compared to pharmaceutical drugs. However, rbNPs exhibited higher anticancer activity than Doxil, a liposomal pharmaceutical formulation of doxorubicin. Additionally, doxorubicin is cytotoxic to both cancer cells and non-cancerous cells, whereas rbNPs are specifically cytotoxic to cancer cells, suggesting that rbNPs are safer than doxorubicin,” highlights Professor Nishikawa.

No adverse effects in mice

To confirm the anticancer properties of rbNPs in the living body, the researchers injected rbNPs into mice having aggressive adenocarcinoma in their peritoneal cavity (enclosed by the diaphragm, abdominal muscles, and pelvis and houses organs like intestines, liver, and kidneys).

They observed significant suppression of tumour growth with no adverse effects on the mice. Additionally, the rbNPs significantly inhibited metastatic growth of murine melanoma B16-BL6 cells in a lung metastasis mouse model.

“By establishing a manufacturing method for rice bran nanoparticles with stable quality and confirming their safety and effectiveness, we can develop drugs for cancer treatment that are sustainable, eco-friendly, and affordable. Consequently, we may be able to help more cancer patients maintain good physical and mental health after treatment,” concludes Professor Nishikawa.

Diana Spencer, Senior Digital Content Editor, DDW

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