Potential evidence of peritoneal recurrence in Stage-II colon cancer from the control arm of CALGB9581.

BACKGROUND: Relapse of early-stage colon cancer (CC) after curative-intent resection occurs. We hypothesized that known risk factors for peritoneal metastases (PM) can define a high-risk state (HRS) that predicts recurrence and mortality. METHODS: CALGB9581 trial patients receiving no adjuvant treatment after stage-II CC resection were included. Positive radial margins, T4 invasion, obstruction/perforation or lymphovascular invasion defined the HRS. Cox proportional hazard models determined association with overall (OS) and disease-free survival (DFS). RESULTS: Median follow-up in 873 included patients was 8.1 years. Five-year OS was 85.8%. HRS+ patients had lower 5-year DFS (68.7 vs. 82.4%, P = 0.003) and OS (75.5 vs. 87.8%, P = 0.001). HRS+ was independently predictive of worse DFS and OS (HR 1.52 and 1.64, P < 0.01). Among recurrences, HRS+ patients showed shorter median OS (3.3 vs. 5.3 years, P = 0.01). CONCLUSIONS: HRS criteria identify a cohort of CC patients at high-risk of recurrence and death. Studies of novel surveillance techniques in such patients are warranted.

RIG-I-Like Receptor LGP2 Is Required for Tumor Control by Radiotherapy.

Dendritic cells (DC) play an essential role in innate immunity and radiation-elicited immune responses. LGP2 is a RIG-I-like receptor involved in cytoplasmic RNA recognition and antiviral responses. Although LGP2 has also been linked to cell survival of both tumor cells and T cells, the role of LGP2 in mediating DC function and antitumor immunity elicited by radiotherapy remains unclear. Here, we report that tumor DCs are linked to the clinical outcome of patients with breast cancer who received radiotherapy, and the presence of DC correlates with gene expression of LGP2 in the tumor microenvironment. In preclinical models, host LGP2 was essential for optimal antitumor control by ionizing radiation (IR). The absence of LGP2 in DC dampened type I IFN production and the priming capacity of DC. In the absence of LGP2, MDA5-mediated activation of type I IFN signaling was abrogated. The MDA5/LGP2 agonist high molecular weight poly I:C improved the antitumor effect of IR. This study reveals a previously undefined role of LGP2 in host immunity and provides a new strategy to improve the efficacy of radiotherapy. SIGNIFICANCE: These findings reveal an essential role of LGP2 in promoting antitumor immunity after radiotherapy and provide a new strategy to enhance radiotherapy.

4-Hydroxyacetophenone modulates the actomyosin cytoskeleton to reduce metastasis.

Metastases are the cause of the vast majority of cancer deaths. In the metastatic process, cells migrate to the vasculature, intravasate, extravasate, and establish metastatic colonies. This pattern of spread requires the cancer cells to change shape and to navigate tissue barriers. Approaches that block this mechanical program represent new therapeutic avenues. We show that 4-hydroxyacetophenone (4-HAP) inhibits colon cancer cell adhesion, invasion, and migration in vitro and reduces the metastatic burden in an in vivo model of colon cancer metastasis to the liver. Treatment with 4-HAP activates nonmuscle myosin-2C (NM2C) (MYH14) to alter actin organization, inhibiting the mechanical program of metastasis. We identify NM2C as a specific therapeutic target. Pharmacological control of myosin isoforms is a promising approach to address metastatic disease, one that may be readily combined with other therapeutic strategies.

DNA Methylation Controls Metastasis-Suppressive 14q32-Encoded miRNAs.

Expression of 14q32-encoded miRNAs is a favorable prognostic factor in patients with metastatic cancer. In this study, we used genomic inhibition of DNA methylation through disruption of DNA methyltransferases DNMT1 and DNMT3B and pharmacologic inhibition with 5-Aza-2'-deoxycytidine (5-Aza-dC, decitabine) to demonstrate that DNA methylation predominantly regulates expression of metastasis-suppressive miRNAs in the 14q32 cluster. DNA demethylation facilitated CCCTC-binding factor (CTCF) recruitment to the maternally expressed gene 3 differentially methylated region (MEG3-DMR), which acts as a cis-regulatory element for 14q32 miRNA expression. 5-Aza-dC activated demethylation of the MEG3-DMR and expression of 14q32 miRNAs, which suppressed adhesion, invasion, and migration (AIM) properties of metastatic tumor cells. Cancer cells with MEG3-DMR hypomethylation exhibited constitutive expression of 14q32 miRNAs and resistance to 5-Aza-dC-induced suppression of AIM. Expression of methylation-dependent 14q32 miRNAs suppressed metastatic colonization in preclinical models of lung and liver metastasis and correlated with improved clinical outcomes in patients with metastatic cancer. These findings implicate epigenetic modification via DNA methylation in the regulation of metastatic propensity through miRNA networks and identify a previously unrecognized action of decitabine on the activation of metastasis-suppressive miRNAs. SIGNIFICANCE: This study investigates epigenetic regulation of metastasis-suppressive miRNAs and the effect on metastasis.

Obstruction predicts worse long-term outcomes in stage III colon cancer: A secondary analysis of the N0147 trial.

BACKGROUND: Patients with colon cancer often present with obstruction. Large series have reported obstruction among the high-risk features, yet prospective data on its specific prognostic influence are lacking. We hypothesized that obstruction is an independent risk factor for poor prognosis in patients with stage III colon cancer. METHODS: N0147 was a trial conducted between 2004 and 2009 that randomly assigned patients with stage III colon cancer to adjuvant regimens of folinic acid (leucovorin calcium), fluorouracil, and oxaliplatin or fluorouracil, leucovorin, and irinotecan, with or without cetuximab. Patient-level data from the control chemotherapy-only arms were obtained. Patient, tumor, and treatment characteristics were abstracted. Disease-free survival and overall survival were estimated by the Kaplan-Meier method. Proportions were compared by χ2 and Fisher exact tests. Univariable and multivariable survival analyses were performed using Cox proportional hazards models. RESULTS: Of 1,543 patients with stage III colon cancer, 250 (16.2%) presented with obstruction. Patients with obstruction were equally likely to complete 12 cycles of adjuvant chemotherapy (75.9% vs 77.1%, P = .6). With median follow-up time of 30.9 months among survivors, five-year overall survival and disease-free survival were worse among patients with obstruction (overall survival 67.7% vs 78.0%, P < .001; disease-free survival 53.9% vs 67.0%, P < .0001). On multivariable analysis, obstruction remained significantly associated with worse survival after adjusting for T stage, N stage, performance status, age, sex, histologic grade, and body mass index (overall survival hazard ratio 1.57, 95% confidence interval 1.12-2.20, P = .001; disease-free survival 1.52, 95% confidence interval 1.18-1.95, P < .001). CONCLUSION: In this prospectively followed cohort of patients with stage III colon cancer treated with adjuvant chemotherapy, obstruction was associated with recurrence and worse survival. Moreover, this effect was independent of T and N stage and histologic grade. These results suggest that obstruction should be incorporated into novel risk-stratification models.