No abstract

Background. The therapeutic resistance of pancreatic ductal adenocarcinoma (PDAC) is partly ascribed to ineffective delivery of chemotherapy to cancer cells. We hypothesized that physical properties at vascular, extracellular, and cellular scales influence delivery of and response to gemcitabine-based therapy.Methods. We developed a method to measure mass transport properties during routine contrast-enhanced CT scans of individual human PDAC tumors. Additionally, we evaluated gemcitabine infusion during PDAC resection in 12 patients, measuring gemcitabine incorporation into tumor DNA and correlating its uptake with human equilibrative nucleoside transporter (hENT1) levels, stromal reaction, and CT-derived mass transport properties. We also studied associations between CT-derived transport properties and clinical outcomes in patients who received preoperative gemcitabine-based chemoradiotherapy for resectable PDAC.Results. Transport modeling of 176 CT scans illustrated striking differences in transport properties between normal pancreas and tumor, with a wide array of enhancement profiles. Reflecting the interpatient differences in contrast enhancement, resected tumors exhibited dramatic differences in gemcitabine DNA incorporation, despite similar intravascular pharmacokinetics. Gemcitabine incorporation into tumor DNA was inversely related to CT-derived transport parameters and PDAC stromal score, after accounting for hENT1 levels. Moreover, stromal score directly correlated with CT-derived parameters. Among 110 patients who received preoperative gemcitabine-based chemoradiotherapy, CT-derived parameters correlated with pathological response and survival.Conclusion. Gemcitabine incorporation into tumor DNA is highly variable and correlates with multiscale transport properties that can be derived from routine CT scans. Furthermore, pretherapy CT-derived properties correlate with clinically relevant endpoints.Trial registration. Clinicaltrials.gov NCT01276613.

Hepatocellular carcinoma (HCC) is one of the most common fatal cancers worldwide. Other than the sorafenib treatment, no effective systemic therapy has been available thus far. Most targets in molecularly targeted therapy for cancer are receptor tyrosine kinases (RTKs). Therefore, identifying activated RTKs in HCC is critical for developing new molecularly targeted therapies. Using a phospho-RTK array, we found that Axl is one of the most frequently activated RTKs in liver cancer cell lines. The knockdown of Axl by RNA interference significantly reduced cell migration and invasion in the HCC cell lines HA22T and Mahlavu. Stimulation of HCC cell lines by Axl ligand growth arrest-specific 6 (Gas6) enhanced cell migration and invasion. The Gas6/Axl pathway enhanced the expression of the epithelial-mesenchymal transition-inducing transcription factor Slug, which is essential for the invasion-promoting activity of Axl. Treating HCC cells with the Axl inhibitor bosutinib suppressed Slug expression and decreased the invasiveness of HCC cell lines. These findings indicate that Gas6/Axl regulates tumor invasion through the transcriptional activation of Slug.

MicroRNAs (miRNAs) play critical roles in embryonic development and are frequently deregulated in human cancers. The let-7 family members are tumor-suppressing miRNAs and are frequently downregulated in cancer cells. Lin-28 and Lin-28B are RNA-binding proteins highly expressed in embryonic tissues. Lin-28 proteins block let-7 precursors from being processed to mature miRNAs by inducing terminal uridylation and degradation of let-7 precursors. Here, we report that Lin-28B, but not Lin-28, is highly expressed in hepatocellular carcinoma (HCC). Lin-28B expression was more frequently noted in high-grade HCCs with high alpha-fetoprotein levels. Knockdown of Lin-28B by RNA interference in the HCC cell line HCC36 suppressed proliferation in vitro and reduced in vivo tumor growth in NOD/SCID mice. In contrast, overexpression of Lin-28B in the HCC cell line HA22T enhanced tumorigenicity. Overexpression of Lin-28B also induced epithelial-mesenchymal transition in HA22T cells and hence, invasion capacity. Large-scale real-time PCR array analysis revealed that, among 380 miRNAs, only let-7/mir-98 family members were regulated by Lin-28B. Lin-28B overexpression enhanced the expression of the known let-7 targets c-myc and HMGA2. It was also found that Lin-28B enhanced the expression of type 1 insulin-like growth factor receptor in a let-7-dependent manner. These results indicate that Lin-28B regulates tumor formation and invasion in HCC through coordinated repression of the let-7/mir-98 family and induction of multiple oncogenic pathways.

Our study indicated that the TERT promoter mutation frequently occurred in HCV-associated HCCs. The absence of Hepatitis B infection was significantly associated with the TERT promoter mutation. These findings suggest that various etiological factors may be involved in differing mechanisms to preserve telomeres during the carcinogenesis of HCCs.