Retnlb, also known as resistin-like molecule beta (RELMbeta), is a bioactive molecule synthesized by intestinal goblet cells [1]. It is involved in the innate host defense of the gastrointestinal tract, as part of the mucus layer which acts as the front line of this defense mechanism.

In a study on hookworm infection using Retnlb -/- mice, it was found that Retnlb can promote the expulsion of the hookworm Nippostrongylus brasiliensis, indicating its role in immunity against such infections [3]. In the context of oral squamous cell carcinoma, data from The Cancer Genome Atlas database showed that Retnlb was upregulated in the tissues and cells of this cancer type. Knockdown of Retnlb significantly reduced the viability, mobility, and invasiveness of cells, suggesting that downregulation of Retnlb may restrain the progression of oral squamous cell carcinoma by inactivating the TLR/2/4/ERK pathway [2]. In colorectal cancer patients, a microarray analysis showed a significant reduction of Retnlb expression in CRC biopsies compared to healthy mucosa, and this reduction was associated with the TNM grade, patients' age, and mutations in KRAS, TP53, and BRAF. Low levels of Retnlb were associated with an unfavorable prognosis [4].

In conclusion, Retnlb plays important roles in immunity and in the progression of certain cancers. The use of gene knockout mouse models has been crucial in revealing its functions in these biological processes and disease conditions, providing valuable insights into its potential as a therapeutic target in oral and colorectal cancers.

References:

1. Kim, Young S, Ho, Samuel B. . Intestinal goblet cells and mucins in health and disease: recent insights and progress. In Current gastroenterology reports, 12, 319-30. doi:10.1007/s11894-010-0131-2. https://pubmed.ncbi.nlm.nih.gov/20703838/

2. Jin, Hong, Miao, Hui, Nie, Yuan-Wen, Lin, Yang-Yang. 2021. Investigating resistin like beta (RETNLB) as a tumor promoter for oral squamous cell carcinoma. In Head & face medicine, 17, 20. doi:10.1186/s13005-021-00272-4. https://pubmed.ncbi.nlm.nih.gov/34158059/

3. Chen, Gang, Wang, Spencer H, Jang, Jessica C, Odegaard, Justin I, Nair, Meera G. 2016. Comparison of RELMα and RELMβ Single- and Double-Gene-Deficient Mice Reveals that RELMα Expression Dictates Inflammation and Worm Expulsion in Hookworm Infection. In Infection and immunity, 84, 1100-1111. doi:10.1128/IAI.01479-15. https://pubmed.ncbi.nlm.nih.gov/26831469/

4. Di Rosa, Michelino, Di Cataldo, Antonio, Broggi, Giuseppe, Raciti, Giuseppina, Li Volti, Giovanni. 2023. Resistin-like beta reduction is associated to low survival rate and is downregulated by adjuvant therapy in colorectal cancer patients. In Scientific reports, 13, 1490. doi:10.1038/s41598-023-28450-1. https://pubmed.ncbi.nlm.nih.gov/36707698/