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Hepatocellular carcinoma (HCC) is the 4th leading cause of cancer-related death worldwide. Despite therapeutic advancements, a significant proportion of patients progress, highlighting the need to improve diagnostic approaches to monitor therapy. Radiofrequency ablation (RFA), an accepted locoregional therapy for early HCC, can stimulate more aggressive tumor biology within under-treated or distant tumors. Increased glycolytic activity is a hallmark feature of cancer, but variations in metabolism and its link to tumor aggression can impact the sensitivity of HCC to therapies affecting these pathways. Tumor metabolic phenotypes can be characterized by hyperpolarized 13C MRI (h13C MRI), which can also be used to assess treatment response. In this study, we used orthotopic rat HCC models with two different cell lines N1S1 and MCA-RH7777, and analyzed their mRNA expression of glycolysis-related genes and in vivo glycolytic activity with h13C MRI. We then partially-treated tumors with radiofrequency ablation (RFA) and used h13C MRI to measure in vivo tumor metabolism before and 3 days after RFA to compare them to histologic and phenotypical measures of disease progression. N1S1 tumors grew only as single lesions, while MCA-RH7777 rapidly produced intra-hepatic and distal metastases. Glycolysis-related genes including HK2, HK3, PFKFB3, and MCT4 were highly expressed in N1S1, but not in MCA-RH7777, while GPT1 was highly expressed in MCA-RH7777 but not in N1S1. In vivo h13C MRI demonstrated significantly increased 13C lactate flux in N1S1 tumor compared to the background normal liver, while 13C lactate flux in MCA-RH7777 rat model did not, consistent with mRNA expression patterns. Tumor 13C lactate flux was significantly increased and 13C alanine flux was significantly decreased following partial RFA treatment to N1S1 tumors when compared to untreated tumors, which was associated with an increase in tumor Ki67 expression. However, no change was seen on h13C MRI between the RFA and control arms in MCA-RH7777 tumors, even though growth and total tumor burden progressed significantly more following RFA. In contrast to N1S1, there was also no difference between 13C lactate flux and 13C alanine flux within MCA-RH7777 tumors and the neighboring normal hepatic parenchyma, suggesting that glycolytic activity in these tumors did not drive RFA-stimulated progression. Targeting of glycolytic pathways as a potential therapy for HCC may therefore be limited to certain subtypes, and h13C MRI may be used to select for sensitivity. Citation Format: Qianhui Dou, Aaron K. Grant, Cody Callahan, Muneeb Ahmed, Leo L. Tsai. Variations in glycolytic activity of HCC subtypes as monitored by in vivo h 13C MRI [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2807.

Breast cancer is the most common cancer among women worldwide, yet successful treatment remains a clinical challenge. Ivermectin, a broad-spectrum antiparasitic drug, has recently been characterized as a potential anticancer agent due to observed antitumor effects. However, the molecular mechanisms involved remain poorly understood. Here, we report a role for ivermectin in breast cancer suppression by activating cytostatic autophagy both in vitro and in vivo. Mechanistically, ivermectin-induced autophagy in breast cancer cells is associated with decreased P21-activated kinase 1 (PAK1) expression via the ubiquitination-mediated degradation pathway. The inhibition of PAK1 decreases the phosphorylation level of Akt, resulting in the blockade of the Akt/mTOR signaling pathway. In breast cancer xenografts, the ivermectin-induced cytostatic autophagy leads to suppression of tumor growth. Together, our results provide a molecular basis for the use of ivermectin to inhibit the proliferation of breast cancer cells and indicate that ivermectin is a potential option for the treatment of breast cancer. Cancer Res; 76(15); 4457–69. ©2016 AACR.

Metastasis is a major cause of death in patients with colorectal cancer, and increasing evidence supports the contribution of the epithelial–mesenchymal transition (EMT) to cancer progression. The dissociation of the E-cadherin/β-catenin adhesion complex represents a key step in EMT and promotes cancer invasion and metastasis, but the upstream signaling pathways regulating this interaction are poorly understood. Here, we show that PDLIM1, a member of the PDZ and LIM protein family, was downregulated in highly metastatic colorectal cancer cells and liver metastases from colorectal cancer patients. We found that loss of PDLIM1 promoted the expression of EMT markers and increased the invasive and migratory properties of multiple colorectal cancer cell lines. Furthermore, PDLIM1 knockdown increased colon-derived liver metastasis in an orthotopic colorectal cancer model and promoted distant metastatic colonization in an experimental lung metastasis model. Mechanistic investigations revealed that PDLIM1 interacted with and stabilized the E-cadherin/β-catenin complex, thereby inhibiting the transcriptional activity of β-catenin and preventing EMT. Accordingly, PDLIM1 overexpression attenuated EMT of colorectal cancer cells. Moreover, the downregulation of PDLIM1 in colorectal cancer samples correlated with reduced E-cadherin and membrane β-catenin levels, and was associated with shorter overall survival. In conclusion, our study demonstrates that PDLIM1 suppresses EMT and metastatic potential of colorectal cancer cells by stabilizing β-catenin at cell–cell junctions, and its loss in metastatic tissues may represent a potential prognostic marker of aggressive disease. Cancer Res; 76(5); 1122–34. ©2015 AACR.

Thermal ablation (TA) is an accepted therapy for early HCC and hepatic metastases from colorectal and breast cancers. However, suboptimal TA is a risk factor for early HCC recurrence and has been associated with a reduction in overall survival. This effect has been attributed to hypoxic response in periablative tissue mediated by HIF-1. Malignant transformation leads to increased anaerobic glycolysis even under normoxic conditions. This process is detectable by hyperpolarized 13C MRI (h13C MRI), which enables real-time high-resolution imaging of the conversion from pyruvate to lactate and may be used as a potential predictor for therapeutic response in HCC. We have identified two potential metabolic regulators and therapeutic targets with a direct link to lactate flux which may be monitored with h13C MRI. PFKFB3 has been identified as a crucial metabolic factor in several cancer types, encoding for inducible 6-phosphofructo-2-kinase and enhancing production of F2,6P2, consequently activating PK1 and glycolysis. Expression levels of PFKFB3 have been found to be higher in malignancies than in normal tissues, attributed to loss of glycolytic control and accelerating neoplastic activity. Hexokinase 3 (HK3), a key catalyst in the first committed steps in glucose metabolism, is also a key promoter involved in epithelial-mesenchymal transition. When we exposed an HCC rat cell line, N1S1, to heat stress, simulating the marginal zone of TA therapy, 20%-90% of cells survived at 40°C-50°C and there was no survival by 55°C. 5-8 days following this treatment, cell proliferation and mRNA expression of glycolysis-related genes were analyzed. Cellular proliferation rate was significantly higher in the heat-treated groups. mRNA expression of PFKFB3 was increased after thermal treatment, while HK3 expression was significantly decreased. We then developed an in vivo orthotopic rat model of a solitary N1S1 HCC and used h13C MRI to measure in vivo tumor lactate flux in response to radiofrequency ablation (RFA), a type of thermal ablation, of adjacent normal hepatic tissue, simulating local treatment of a distant lesion. h13C MRI demonstrated significantly increased tumor 13C lactate flux in the RFA arm relative to the control group (change in lactate-to-pyruvate ratio of 0.236±0.278 vs -0.035±0.107, p=0.0465, n=6), while background liver lactate flux was unchanged. We found that this correlated with mRNA expression of PFKFB3 and HK3, which was statistically significantly greater within tumors from the RFA group compared to control tumors (PFKFB3, 1.052±0.091 vs 0.655±0.294, p=0.0004, n=6; HK3, 0.751±0.130 vs 0.501±0.163, p=0.0036, n=6). The PFKFB3 expression patterns were concordant between in vitro and in vivo experiments. Our data shows that PFKFB3 may be an attractive treatment target for HCC, and h13C MRI may be a noninvasive technique well-suited to monitor treatment response. Citation Format: Qianhui Dou, Aaron K. Grant, Cody Callahan, David Mwin, Muneeb Ahmed, Leo L. Tsai. 13C-MRI detects increased lactate flux in HCC following hepatic thermal A\ablation and correlates with PFKFB3 Expression [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2785.