An arabinogalactan polysaccharide known as RN1 can be extracted from the flower (San Qi Hua) of the chinese medicine herb Panax notoginseng . In Latin, the word panax means “cure-all”. According to Chinese medicine (Figure 1) it is warm in nature, with a sweet but slightly bitter taste. A concoction incorporating Panax notoginseng was carried by the Viet Cong to deal with wounds during the Vietnam war.
|Figure 1: Yu Garden and Bazaar – Located in the heart of Old Town Shanghai, it includes a 5-acre classical Chinese garden, and the City God Daoist Temple. Credit: Lyn Gateley. No changes were made. Creative Commons Attribution 2.0 Generic (CC BY 2.0).|
RN1 is a 20.5 kDa arabinogalactan polysaccharide. A recent study found that it inhibited the growth of two commonly used pancreatic cancer cell lines but not cell lines originating from other cancers (A549, MDA-MB-231, A172, HeLa) . It also did not affect the immortalised pancreatic duct epithelial cell line HPDE6-C7. This suggests a possible synthetic lethality specific for pancreatic cancer. In addition RN1 reduced the tumour volume of both BxPC-3 cell line and pancreatic cancer patient derived mouse xenografts.
Galectin-3 (Gal-3) is upregulated in pancreatic cancer (see here). The authors found that RN1 bound to Gal-3 and down-regulated its protein expression in pancreatic cancer cell lines. Gal-3 induces the EGFR, BMPR, and Integrin signalling pathways and the authors provided evidence that RN1 modulated the activity of all three of these pathways in pancreatic cancer cell lines. Interestingly RN1 inhibited Runx2 expression which is known to mediate gemcitabine resistance in pancreatic cancer cell lines (see here). The targeting of Gal-3 is an interesting strategy for pancreatic cancer therapeutic development.
- 丁侃, 王培培, 张蕾 (2015). Arabinogalactan of flowers of panax notoginseng (burK.)F.H.Chen, and preparation method and use thereof. Chinese patent CN 104710538 A. Jun 17, 2015.
- Zhang L, Wang P, Qin Y, Cong Q, Shao C, Du Z, Ni X, Li P, Ding K. RN1, a novel galectin-3 inhibitor, inhibits pancreatic cancer cell growth in vitro and in vivo via blocking galectin-3 associated signaling pathways. Oncogene. 2016 Sep 12. Doi: 10.1038/onc.2016.306. PubMed PMID: 27617577.