An Msh2 conditional knockout mouse for studying intestinal cancer and testing anticancer agents.

BACKGROUND & AIMS: Mutations in the DNA mismatch repair (MMR) gene MSH2 cause Lynch syndromes I and II and sporadic colorectal cancers. Msh2(null) mice predominantly develop lymphoma and do not accurately recapitulate the colorectal cancer phenotype. METHODS: We generated and examined mice with a conditional Msh2 disruption (Msh2(LoxP)), permitting tissue-specific gene inactivation. ECMsh2(LoxP/LoxP) mice carried an EIIa-Cre transgene, and VCMsh2(LoxP/LoxP) mice carried a Villin-Cre transgene. We combined the VCMsh2(LoxP) allele with either Msh2(Delta7null) (VCMsh2(LoxP/null)) or Msh2(G674D) mutations (VCMsh2(LoxP/G674D)) to create allelic phase mutants. These mice were given cisplatin or 5-fluorouracil/leucovorin and oxaliplatin (FOLFOX), and their tumors were measured by magnetic resonance imaging. RESULTS: Embryonic fibroblasts from ECMsh2(LoxP/LoxP) mice do not express MSH2 and are MMR deficient. Reverse transcription, polymerase chain reaction, and immunohistochemistry from VCMsh2(LoxP/LoxP) mice demonstrated specific loss of Msh2 messenger RNA and protein from epithelial cells of the intestinal tract. Microsatellite instability was observed in all VCMsh2 strains and limited to the intestinal mucosa. Resulting adenomas and adenocarcinomas had somatic truncation mutations to the adenomatous polyposis coli (Apc) gene. VCMsh2(LoxP/LoxP) mice did not develop lymphoma. Comparison of allelic phase tumors revealed significant differences in multiplicity and size. When treated with cisplatin or FOLFOX, tumor size was reduced in VCMsh2(LoxP/G674D) but not VCMsh2(LoxP/null) tumors. The apoptotic response to FOLFOX was partially sustained in the intestinal mucosa of VCMsh2(LoxP/G674D) animals. CONCLUSIONS: Msh2(LoxP/LoxP) mice in combination with appropriate Cre recombinase transgenes have excellent potential for preclinical modeling of Lynch syndrome, MMR-deficient tumors of other tissue types, and use in drug development.

Loss of Rb1 in the gastrointestinal tract of Apc1638N mice promotes tumors of the cecum and proximal colon.

To examine the role of Rb1 in gastrointestinal (GI) tumors, we generated mice with an Apc(1638N) allele, Rb(tm2brn) floxed alleles, and a villin-cre transgene (RBVCA). These animals had exon 19 deleted from Rb1 throughout the GI tract. We have shown previously that Rb1 deficiency is insufficient for GI tumor initiation, with inactivation of an Apc allele capable of overcoming the insufficiency. In this study we demonstrate that RBVCA mice have reduced median survival because of an increase in tumor incidence and multiplicity in the cecum and the proximal colon. Large intestinal tumors are predominantly adenomas, whereas the tumors of the small intestine are a mixture of adenomas and adenocarcinomas. We find truncation mutations to the second Apc allele in tumors of both the large and small intestine. Expression profiles of duodenal and cecal tumors relative to each other show unique gene subsets up and down regulated. Substantial expression patterns compare to human colorectal cancer, including recapitulation of embryonic genes. Our results indicate that Rb1 has significant influence over tumor location in the GI tract, and that both cecal and duodenal tumors initiate through inactivation of Apc. Expression profile analysis indicates the two tumor types differentially regulate distinct sets of genes that are over-expressed in a majority of human colorectal carcinomas.

Acupuncture for chemotherapy-induced neutropenia in patients with gynecologic malignancies: a pilot randomized, sham-controlled clinical trial.

OBJECTIVES: The objective of this study was to investigate the effect of acupuncture administered during myelosuppressive chemotherapy on white blood cell (WBC) count and absolute neutrophil count (ANC) in patients with ovarian cancer. DESIGN: This study is a pilot, randomized, sham-controlled clinical trial. Patients received active acupuncture versus sham acupuncture while undergoing chemotherapy. A standardized acupuncture protocol was employed with manual and electrostimulation. The frequency of treatment was 2-3 times per week for a total of 10 sessions, starting 1 week before the second cycle of chemotherapy. SETTING: The setting was two outpatient academic centers for patients with cancer. SUBJECTS: Twenty-one (21) newly diagnosed and recurrent ovarian cancer patients were the subjects. OUTCOME MEASURES: WBC count, ANC, and plasma granulocyte colony-stimulating factor (G-CSF ) were assessed weekly. RESULTS: The median leukocyte value in the acupuncture arm at the first day of the third cycle of chemotherapy was significantly higher than in the control arm after adjusting for baseline value (8600 cells/microL, range: 4800-12,000 versus 4400 cell/microL, range: 2300-10,000) (p = 0.046). The incidence of grade 2-4 leukopenia was less in the acupuncture arm than in the sham arm (30% versus 90%; p = 0.02). However, the median leukocyte nadir, neutrophil nadir, and recovering ANC were all higher but not statistically significantly different (p = 0.116-0.16), after adjusting for baseline differences. There were no statistically significant differences in plasma G-CSF between the two groups. CONCLUSIONS: We observed clinically relevant trends of higher WBC values during one cycle of chemotherapy in patients with ovarian cancer, which suggests a potential myeloprotective effect of acupuncture. A larger trial is warranted to more definitively determine the efficacy of acupuncture on clinically important outcomes of chemotherapy-induced neutropenia.