Inhibition of Fatty Acid Synthase Attenuates CD44-Associated Signaling and Reduces Metastasis in Colorectal Cancer

Fatty acid synthase (FASN) and ATP-citrate lyase, key enzymes of de novo lipogenesis, are significantly upregulated and activated in many cancers and portend poor prognosis. Even though the role of lipogenesis in providing proliferative and survival advantages to cancer cells has been described, the impact of aberrant activation of lipogenic enzymes on cancer progression remains unknown. In this study, we found that elevated expression of FASN is associated with advanced stages of colorectal cancer (CRC) and liver metastasis, suggesting that it may play a role in progression of CRC to metastatic disease. Targeted inhibition of lipogenic enzymes abolished expression of CD44, a transmembrane protein associated with metastases in several cancers including CRC. In addition, inhibition of lipogenic enzymes and reduced expression of CD44 attenuated the activation of MET, Akt, FAK, and paxillin, which are known to regulate adhesion, migration, and invasion. These changes were consistent with an observed decrease in migration and adhesion of CRC cells in functional assays and with reorganization of actin cytoskeleton upon FASN inhibition. Despite the modest effect of FASN inhibition on tumor growth in xenografts, attenuation of lipogenesis completely abolished establishment of hepatic metastasis and formation of secondary metastasis. Together, our findings suggest that targeting de novo lipogenesis may be a potential treatment strategy for advanced CRC

Molecular Landscape of Small Bowel Adenocarcinoma

Small bowel adenocarcinoma (SBA) is a rare malignancy, with lower incidence, later stage at diagnosis, and poor overall prognosis compared to other cancers of the gastrointestinal tract. Owing to the rarity of the disease along with the paucity of high-quality tissue samples and preclinical models, little is known about the molecular alterations characteristic of SBA. This is reflected by the fact that the clinical management of SBA is primarily extrapolated from colorectal cancer (CRC). Recent advances in genomic profiling have highlighted key differences between these tumors, establishing SBA as a molecularly unique intestinal cancer. Moreover, comprehensive molecular analysis has identified a relatively high incidence of potentially targetable genomic alterations in SBA, predictive of response to targeted and immunotherapies. Further advances in our knowledge of the mutational and transcriptomic landscape of SBA, guided by an increased understanding of the molecular drivers of SBA, will provide opportunities to develop novel diagnostic tools and personalized therapeutic strategies

mTORC1 and mTORC2 Regulate EMT, Motility, and Metastasis of Colorectal Cancer via RhoA and Rac1 Signaling Pathways

Activation of phosphoinositide 3-kinase (PI3K)/Akt signaling is associated with growth and progression of colorectal cancer (CRC). We have previously shown that the mTOR kinase, a downstream effector of PI3K/Akt signaling, regulates tumorigenesis of CRC. However, the contribution of mTOR and its interaction partners toward regulating CRC progression and metastasis remains poorly understood. We found that increased expression of mTOR, Raptor, and Rictor mRNA was noted with advanced stages of CRC, suggesting that mTOR signaling may be associated with CRC progression and metastasis. mTOR, Raptor, and Rictor protein levels were also significantly elevated in primary CRCs (stage IV) and their matched distant metastases compared with normal colon. Inhibition of mTOR signaling, using rapamycin or stable inhibition of mTORC1 (Raptor) and mTORC2 (Rictor), attenuated migration and invasion of CRCs. Furthermore, knockdown of mTORC1 and mTORC2 induced a mesenchymal-epithelial transition (MET) and enhanced chemosensitivity of CRCs to oxaliplatin. We observed increased cell-cell contact and decreased actin cytoskeletal remodeling concomitant with decreased activation of the small GTPases, RhoA and Rac1, upon inhibition of both mTORC1 and mTORC2. Finally, establishment of CRC metastasis in vivo was completely abolished with targeted inhibition of mTORC1 and mTORC2 irrespective of the site of colonization. Our findings support a role for elevated mTORC1 and mTORC2 activity in regulating epithelial-mesenchymal transition (EMT), motility, and metastasis of CRCs via RhoA and Rac1 signaling. These findings provide the rationale for including mTOR kinase inhibitors, which inhibit both mTORC1 and mTORC2, as part of the therapeutic regimen for CRC patients

Molecular differences with therapeutic implications in early-onset compared to average-onset cholangiocarcinoma

536 Background: Early-onset cholangiocarcinoma (eoCCA) is among early-onset cancers with the fastest rising rates, yet little is known about its biology. We sought to compare the molecular characteristics of eoCCA with average-onset CCA (aoCCA) with an age cut-off of 50 years, utilizing a real-world multi-omics dataset. Methods: The study comprised patients whose tumors underwent molecular analysis at Caris Life Sciences (Phoenix, AZ) using whole exome and whole transcriptome analyses. Patients were categorized by age as eoCCA defined as 50 years. Gene expression profiles were analyzed for transcriptional signatures predictive of immunotherapy response including the T-cell inflamed score (TIS) and interferon-gamma (IFG) score. P values (adjusted for multiple testing) were considered significant at False Discovery Rate (FDR) P<0.05 for molecular comparisons and FDR P<0.25 for Gene Set Enrichment Analysis (GSEA). Insurance claims data was used for survival comparison using Kaplan-Meier estimates. Results: The study included 5587 patients - 453 patients with eoCCA and 5134 with aoCCA (Table). Of targetable mutations ( FGFR2, IDH1, IDH2, ERBB2, BRCA, BRAF), FGFR2 fusion was significantly more prevalent in eoCCA (15.7% vs 5.9% in aoCCA, FDR P<0.001). Rates trended higher in eoCCAfor MSI-H tumors (4.1% vs 2.4%), and high tumor mutational burden (6.1% vs 5.1%) but not significantly different (FDR P=1). The IFG score (Fold Change FC: 1.1, FDR P=0.01) and TIS (FC:17.3, FDR P=0.03) were significantly higher in aoCCA vs eoCCA. On GSEA, angiogenesis was enriched in eoCCA (normalized enrichment score NES=1.51, FDR P=0.16) while IFG (NES= -1.58, FDR P =0.06) and inflammatory response (NES= -1.46, FDR P=0.18) were enriched in aoCCA. Median OS was longer in eoCCA (16.5 vs 13.3 months, Hazard Ratio (HR) 0.86, 95%CI 0.78-0.95, P=0.004). Among patients treated with immunotherapy, median OS was longer in patients with eoCCA (19.2 months, n=19) vs aoCCA (7.6 months, n=150) - HR 0.52, 95%CI 0.28-0.94, p=0.03. No survival difference was identified in patients on chemotherapy (HR 0.91, 95%CI 0.76-1.08, P=0.28). Conclusions: In the largest age-stratified analysis of molecular characteristics of CCA, we identified crucial differences, including higher prevalence of FGFR2 fusions and significant differences in immunotherapy-related markers, angiogenesis enrichment, and inflammatory response. Patients with eoCCA experienced better outcomes with immunotherapy even though immune-oncology-relevant markers favored aoCCA. Our findings, especially higher FGFR2 fusion prevalence in eoCCA, underscore the need for NGS testing and the potential for age-tailored therapeutic strategies. [Table: see text