Muscarinic receptor subtype-3 gene ablation and scopolamine butylbromide treatment attenuate small intestinal neoplasia in Apcmin/+ mice

Abstract

M3 subtype muscarinic receptors (CHRM3) are over-expressed in colon cancer. In this study, we used Apc(min/+) mice to identify the role of Chrm3 expression in a genetic model of intestinal neoplasia, explored the role of Chrm3 in intestinal mucosal development and determined the translational potential of inhibiting muscarinic receptor activation. We generated Chrm3-deficient Apc(min/+) mice and compared intestinal morphology and tumor number in 12-week-old Apc(min/+)Chrm3(-/-) and Apc(min/+)Chrm3(+/+) control mice. Compared with Apc(min/+)Chrm3(+/+) mice, Apc(min/+)Chrm3(-/-) mice showed a 70 and 81% reduction in tumor number and volume, respectively (P < 0.01). In adenomas, β-catenin nuclear staining was reduced in Apc(min/+)Chrm3(-/-) compared with Apc(min/+)Chrm3(+/+) mice (P < 0.02). Whereas Apc gene mutation increased the number of crypt and Paneth cells and decreased villus goblet cells, these changes were absent in Apc(min/+)Chrm3(-/-) mice. To determine whether pharmacological inhibition of muscarinic receptor activation attenuates intestinal neoplasia, we treated 6-week-old Apc(min/+) mice with scopolamine butylbromide, a non-subtype-selective muscarinic receptor antagonist. After 8 weeks of continuous treatment, scopolamine butylbromide-treated mice showed a 22% reduction in tumor number (P = 0.027) and a 36% reduction in tumor volume (P = 0.004) as compared with control mice. Compared with Chrm3 gene ablation, the muscarinic antagonist was less efficacious, most probably due to shorter duration of treatment and incomplete blockade of muscarinic receptors. Overall, these findings indicate that interplay of Chrm3 and β-catenin signaling is important for intestinal mucosal differentiation and neoplasia and provide a proof-of-concept that pharmacological inhibition of muscarinic receptor activation can attenuate intestinal neoplasia in vivo.

Microangiopathy triggers, and inducible nitric oxide synthase exacerbates dextran sulfate sodium-induced colitis

“…Briefly, mice were given 2% (wt/vol) DSS in their drinking water. At 30 h of DSS administration, an osmotic minipump (1007D; Alzet, Cupertino, CA, USA) that had been filled with PBS containing butylscopolamine (also known as scopolamine N-butylbromide, 5 μg/g body weight/day; S7882-1G; Sigma-Aldrich) was embedded in the subcutaneous tissue of the back 29 under isoflurane inhalation anesthesia. The DAI of each mouse was calculated each day from the beginning of DSS administration.…”

Bedside to Bench: Role of Muscarinic Receptor Activation in Ultrarapid Growth of Colorectal Cancer in a Patient With Pheochromocytoma

“…8 Collectively, these findings provide evidence that muscarinic receptor agonists may be important growth factors in colon cancer. Indeed, in mouse models of intestinal neoplasia, deficiency of CHRM3 , the gene encoding M3R, robustly attenuates intestinal tumor formation, 9,10 whereas treatment with a muscarinic receptor agonist promotes tumorigenesis. 11 …”

Animal Models of Colorectal Cancer in Chemoprevention and Therapeutics Development

“…Mouse models with loss of function of MMR genes have been generated and mice lacking Mlh1, Msh2 and Msh6 develop tumors in stomach, small intestine, and colon. However, these mice also develop cancers of the lymphatic system, skin and lung (Reitmair et al, 1996;Edelmann et al, 1997Edelmann et al, , 2000. Enhanced development of adenomas was observed in the APC Min/+ mice lacking Msh2 with increase in colonic adenoma numbers.…”

“…Enhanced development of adenomas was observed in the APC Min/+ mice lacking Msh2 with increase in colonic adenoma numbers. Interestingly, these mice show normal growth and can reproduce but have reduced life span (Reitmair et al, 1996). Although loss of Msh3 is not associated with increased tumors, loss of both the Msh3 and Msh6 leads to an increase in GI tumors at a younger age, similar to Mlh1 or Msh2-deficient mice (Edelmann et al, 2000).…”

“…Mice bearing mutations in the Msh6 gene have a life span of 18 months and develop GI tumors within one year. The MMR mouse models carrying one functional copy of APC showed increasing mutation of APC and an enhanced frequency of intestinal neoplasia (Reitmair et al, 1996;Kuraguchi et al, 2001). Furthermore, mice lacking Mlh1 in APC1638N model have a 40-fold increase in adenomas compared to APC1638N mice alone .…”