Multiple organs exhibit exacerbated cachexia in male mice with colon cancer than females

Cachexia is a lethal syndrome with massive muscle wasting that occurs in 60 % of colon cancer patients. Several studies in humans and mice show that males are more prone than females to muscle atrophy caused by colorectal cancer. Understanding whether muscle atrophy precedes or follows other organ alterations may unravel the sex-specific drivers of cachexia.

In two mouse models of colon cancer, we explored when cachexia affects multiple organs in both sexes and their sex development, if/how sex hormone may affect in vitro the inflammatory state of colon adenocarcinoma C26, HCT116 and human primary colorectal cancer cells and in vivo the progression of cachexia in C26-carriers.

We compared tumor growth and cachexia-related responses in C26 males and females and C57BL/6J-Apc^Min/+ mice of both sexes. C26, HCT116 and human primary colorectal cancer cells exposed to 17β-estradiol or the antagonist fulvestrant were analysed for Il-6 expression and secretion. β-estradiol 3-benzoate was given to C26 males.

In both models, cancer-bearing males display more/earlier muscle wasting than females. Muscle proteasome activity is enhanced only in cachectic males and only when they are sexually mature. During cachexia hypogonadism appears earlier in males than females of both models. Tumor-bearing females as long as they are "cycling" are more preserved from cachexia than males. Circulating levels of IL-6 increased more in C26 males than C26 females and spleens were bigger in C26 males also displaying more atrophic and inflamed muscles. 17β-estradiol halved the expression of Il-6 and abrogated the secretion of IL-6 from C26 cells, while fulvestrant surprisingly highly enhanced Il-6 expression, supporting an anti-inflammatory effect of estrogens directly on C26 cells. Similar data were obtained from human (primary) colorectal cancer cells. In vivo β-estradiol 3-benzoate prevented some signs of cachexia in C26 carriers.

Overall, we herein report a novel direct role of 17β-estradiol on colon cancer cells explaining why multiple tissues from males display more signs of cachexia than females.