Kristin E. Cox

Background/Objectives: Identifying novel targets to treat gastric cancer (GC) has become a focus of research in recent years. Our accelerated Helicobacter-induced gastric cancer mouse model allowed us to identify several differentially expressed genes (DEGs), including Psmb8 (proteasome subunit beta type 8, also called Lmp7), which was also found to be elevated in GC patient samples. PSMB8 encodes one of the immune subunits of the immunoproteasome, which has been associated with disease severity in multiple cancers. Methods: We identified carfilzomib from a public database as a potential drug targeting PSMB8; it effectively halts immunoproteasome activity, leading to apoptosis. We tested carfilzomib’s efficacy against gastric cancer by subcutaneously implanting nude mice with human gastric epithelial-derived tumors and treating them with carfilzomib, either alone or in combination with 5-fluorouracil (5-FU), a standard-of-care drug. The effectiveness of drug treatment was measured by tumor growth, cell proliferation, and apoptosis. Results: We observed that carfilzomib retarded tumor growth, inhibited cell proliferation, and induced apoptosis. Conclusions: These results strongly suggest that PSMB8 is a suitable candidate for targeted therapy. Moreover, with carfilzomib having robust anti-tumor activity, it has potential as a treatment option for cancers where high levels of PSMB8 are associated with poor overall survival.

Background/Purpose: The only potentially curative procedure for pancreatic cancer is R0 resection, which is difficult to achieve due to poorly defined tumor margins. In the present study, we used an anti-CA19-9 antibody conjugated to a near-infrared fluorophore in orthotopic mouse models to target and visualize pancreatic cancer. Methods: Orthotopic models of the human pancreatic cancer cell lines SW1990 and BxPC3 were established by implanting tumor fragments into the pancreas of athymic nude mice. Anti-CA19-9 and control IgG were conjugated with IRDye800CW. Mice received 50 µg of CA19-9–IRDye800CW or IgG-IRDye800CW via tail-vein injection and were imaged after 72 h. MIA PaCa-2, a CA19-9-negative cell line, was used in subcutaneous models to assess targeting specificity. Results: Using the LI-COR Pearl imaging system in the SW1990 model, the tumor-to-pancreas ratio (TPR) was 4.51 (±0.74), and the tumor to the liver ratio (TLR) was 3.05 (±0.60) with CA19-9-IRDye800CW, while the TPR was 1.67 (±0.16) and the TLR was 0.95 (±0.05) for the non-specific control IgG–IRDye800CW. Using a clinically available fluorescence laparoscope, CA19-9-1RDye800CW demonstrated a TPR of 2.34 (±0.44) and a TLR of 2.23 (±0.49), compared to 1.11 (±0.13) and 0.69 (±0.07), respectively, for IgG-IRDye800CW in the SW1990 orthotopic model. In the BxPC3 models, the TPR was 3.82 (±0.55) and the TLR was 4.13 (±0.77) for CA19-9-IRDye800CW compared to 2.40 (±0.31) and 1.49 (±0.23), respectively, for IgG-IRDye800CW. Conclusions: CA19-9-IRDye800CW provided specific in vivo targeting of two human pancreatic cancer cell lines in orthotopic nude mouse models with superior TPRs and TLRs compared to IgG-IRDye800CW. This tumor-specific fluorescent CA19-9 antibody is a promising clinical tool for improved visualization of pancreatic cancer.

Background/Objectives: Pancreatic cancer is the third leading cause of death related to cancer. The only possible cure presently is complete surgical resection; however, this is limited by difficulty in clearly defining tumor margins. Enhancement of the visualization of pancreatic ductal adenocarcinoma (PDAC) tumor margins using near-infrared dye-conjugated tumor-specific antibodies was pioneered by using anti-CEA, anti-CA19.9, and anti-MUC5AC in orthotopic mouse models of pancreatic cancer. Recently, an antibody to Mucin 4 (MUC4) conjugated to a fluorescent probe has shown promise in targeting colon tumors in orthotopic mouse models. Methods: In the present study, we targeted pancreatic cancer using an anti-MUC4 antibody conjugated to IRDye800 (anti-MUC4-IR800) in orthotopic mouse models. Two pancreatic cancer human cell lines were used, SW1990 and CD18/HPAF. Results: Anti-MUC4-IR800 targeted the two pancreatic cancer cell line tumors in orthotopic mouse models with high tumor-to-pancreas ratios and high tumor-to-liver ratios, with greater targeting seen in SW1990. Conclusions: The present results suggest anti-MUC4-IR800’s potential to be used in fluorescence-guided surgical resection of pancreatic cancer.

Background: The present study aimed to validate the accuracy of a tumor-specific antibody to target liver metastases of colorectal cancer. Methods: A humanized anti-CEA antibody conjugated to a fluorescent dye (M5A-IR800) was tested for targeting human colorectal cancer liver metastases (CRLMs) expressing luciferase in an orthotopic mouse model. Orthotopic mouse models of CRLMs were established by implanting fragments of a luciferase-expressing human colorectal cancer cell line, LS174T, in the liver of nude mice. Mice received 50 µg M5A-IR800 72 h prior to imaging. To test co-localization, bioluminescence imaging was performed using D-luciferin, which was given via intraperitoneal injection just prior to imaging. Results: Tumors were able to be visualized non-invasively through the skin with the luciferase–luciferin signal. Intra-abdominal imaging showed accurate labeling of CRLMs with M5A-IR800, which co-localized with the luciferase–luciferin signal. Conclusions: The present results validate the accuracy of a tumor-specific anti-CEA antibody in targeting liver metastases of colorectal cancer.

Claudins (CLDN1–CLDN24) are a family of tight junction proteins whose dysregulation has been implicated in tumorigeneses of many cancer types. In colorectal cancer (CRC), CLDN1, CLDN2, CLDN4, and CLDN18 have been shown to either be upregulated or aberrantly expressed. In the normal colon, CLDN1 and CLDN3–7 are expressed. Although a few claudins, such as CLDN6 and CLDN7, are expressed in CRC their levels are reduced compared to the normal colon. The present review outlines the expression profiles of claudin proteins in CRC and those that are potential biomarkers for prognostication.

Accurately identifying metastatic disease is critical to directing the appropriate treatment in pancreatic cancer. Mucin 5AC is overexpressed in pancreatic cancer but absent in normal pancreas tissue. The present proof-of-concept study demonstrates the efficacy of an anti-mucin 5AC antibody conjugated to an IR800 dye (MUC5AC-IR800) to preferentially label a liver metastasis of pancreatic cancer (Panc Met) in a unique patient-derived orthotopic xenograft (PDOX) model. In orthotopic models, the mean tumor to background ratio was 1.787 (SD ± 0.336), and immunohistochemistry confirmed the expression of MUC5AC within tumor cells. MUC5AC-IR800 provides distinct visualization of pancreatic cancer liver metastasis in a PDOX mouse model, demonstrating its potential utility in staging laparoscopy and fluorescence-guided surgery.

Poor visualization of polyps can limit colorectal cancer screening. Fluorescent antibodies to mucin5AC (MUC5AC), a glycoprotein upregulated in adenomas and colorectal cancer, could improve screening colonoscopy polyp detection rate. Adenomatous polyposis coli flox mice with a Cdx2-Cre transgene (CPC-APC) develop colonic polyps that contain both dysplastic and malignant tissue. Mice received MUC5AC-IR800 or IRdye800 as a control IV and were sacrificed after 48 h for near-infrared imaging of their colons. A polyp-to-background ratio (PBR) was calculated for each polyp by dividing the mean fluorescence intensity of the polyp by the mean fluorescence intensity of the background tissue. The mean 25 μg PBR was 1.70 (±0.56); the mean 50 μg PBR was 2.64 (±0.97); the mean 100 μg PBR was 3.32 (±1.33); and the mean 150 μg PBR was 3.38 (±0.87). The mean PBR of the dye-only control was 2.22 (±1.02), significantly less than the 150 μg arm (p-value 0.008). The present study demonstrates the ability of fluorescent anti-MUC5AC antibodies to specifically target and label colonic polyps containing high-grade dysplasia and intramucosal adenocarcinoma in CPC-APC mice. This technology can potentially improve the detection rate and decrease the miss rate of advanced colonic neoplasia and early cancer at colonoscopy.

Mucins (MUC1–MUC24) are a family of glycoproteins involved in cell signaling and barrier protection. They have been implicated in the progression of numerous malignancies including gastric, pancreatic, ovarian, breast, and lung cancer. Mucins have also been extensively studied with respect to colorectal cancer. They have been found to have diverse expression profiles amongst the normal colon, benign hyperplastic polyps, pre-malignant polyps, and colon cancers. Those expressed in the normal colon include MUC2, MUC3, MUC4, MUC11, MUC12, MUC13, MUC15 (at low levels), and MUC21. Whereas MUC5, MUC6, MUC16, and MUC20 are absent from the normal colon and are expressed in colorectal cancers. MUC1, MUC2, MUC4, MUC5AC, and MUC6 are currently the most widely covered in the literature regarding their role in the progression from normal colonic tissue to cancer.