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Simple Summary: Since TIM-3 on T cells or dendritic cells (DCs) has recently emerged as an attractive target for immunotherapy, we examined its expression on DCs using transcriptomic data from a public database and immunohistochemical evaluations from our cohorts of colorectal cancer. The expression of HAVCR2 (TIM-3) was strongly associated with the infiltration of DCs within the tumor microenvironment, and immunohistochemical staining of clinical tissue samples revealed that tumor-infiltrating DCs expressed TIM-3; however, their number at the tumor-invasive front significantly decreased with stage progression. Among vitro-generated DCs, TIM-3 expression was higher on immature DCs than on mature DCs, while Western blotting showed that STING expression was higher on mature DCs than on immature DCs. TIM-3 was originally identified as a negative regulator of helper T cells and is expressed on dendritic cells (DCs). Since the inhibition of TIM-3 on DCs has been suggested to enhance T cell-mediated anti-tumor immunity, we examined its expression on DCs within the tumor microenvironment (TME) in colorectal cancer (CRC) using transcriptomic data from a public database (n = 592) and immunohistochemical evaluations from our cohorts of CRC (n = 115). The expression of TIM-3 on DCs in vitro was examined by flow cytometry, while the expression of its related molecules, cGAS and STING, on immature and mature DCs was assessed by Western blotting. The expression of HAVCR2 (TIM-3) was strongly associated with the infiltration of DCs within the TME of CRC. Immunohistochemical staining of clinical tissue samples revealed that tumor-infiltrating DCs expressed TIM-3; however, their number at the tumor-invasive front significantly decreased with stage progression. TIM-3 expression was higher on immature DCs than on mature DCs from several different donors (n = 6). Western blot analyses showed that the expression of STING was higher on mature DCs than on immature DCs, which was opposite to that of TIM-3. We demonstrated that TIM-3 was highly expressed on tumor-infiltrating DCs of CRC and that its expression was higher on immature DCs than on mature DCs. [ABSTRACT FROM AUTHOR]

Simple Summary: Although the tumor cell-intrinsic cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway plays a crucial role in activating immune cells in the tumor microenvironment in colorectal cancer (CRC), its impact on the infiltration of immune cells and clinical outcomes in patients with mismatch repair proficient/microsatellite stable (pMMR/MSS) CRC has not been thoroughly investigated. In this study, we examine the expression pattern of cGAS-STING in tumor cells and its effect on the infiltrations of CD8+ and CD4+ T cells, as well as clinical outcomes including survival and recurrence in patients with pMMR/MSS CRC. Our current findings may offer novel insights and therapeutic strategies for patients with pMMR/MSS CRC. The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway plays a crucial role in activating immune cells in the tumor microenvironment, thereby contributing to a more favorable response to immune checkpoint inhibitors (ICI) in colorectal cancer (CRC). However, the impact of the expression of cGAS-STING in tumor cells on the infiltration of CD8+ T cells and clinical outcomes in mismatch repair proficient/microsatellite stable (pMMR/MSS) CRC remains largely unknown. Our findings reveal that 56.8% of all pMMR CRC cases were cGAS-negative/STING-negative expressions (cGAS−/STING−) in tumor cells, whereas only 9.9% of all pMMR CRC showed cGAS-positive/STING-positive expression (cGAS+/STING+) in tumor cells. The frequency of cGAS+/STING+ cases was reduced in the advanced stages of pMMR/MSS CRC, and histone methylation might be involved in the down-regulation of STING expression in tumor cells. Since the expression level of cGAS-STING in tumor cells has been associated with the infiltration of CD8+ and/or CD4+ T cells and the frequency of recurrence in pMMR/MSS CRC, decreased expression of cGAS-STING in tumor cells might lead to poor immune cell infiltration and worse prognosis in most pMMR/MSS CRC patients. Our current findings provide a novel insight for the treatment of patients with pMMR/MSS CRC. [ABSTRACT FROM AUTHOR]

Phosphoribosylaminoimidazole carboxylase, phosphoribosylaminoimidazole succinocarboxamide synthetase (PAICS) encodes an enzyme that catalyzes de novo purine biosynthesis. Although PAICS has been implicated as a potential therapeutic target in several cancers, its clinical and prognostic significance in colorectal cancer (CRC) is not fully understood. To elucidate the roles of PAICS in CRC, we investigated PAICS expression in four cohorts consisting of a total of 1659 samples based on quantitative RT-PCR, microarray and RNA-seq analysis. Despite upregulated PAICS levels in tumor compared to those of normal mucosa, we found a decreasing trend of PAICS expression during tumor progression and metastasis. We conducted immunohistochemistry on 252 specimens, showing that PAICS protein was strongly expressed in the majority of CRCs, but not in adjacent mucosa. Notably, 29.0% of tumors lacked PAICS staining, and PAICS-negative expression in tumor had significant prognostic impact on poor cancer-specific survival in stage III CRC. Correspondingly, decreased levels of PAICS transcript were also correlated with poor relapse-free survival particularly in stage III patients, and this finding was robustly confirmed in three microarray datasets of a total of 802 stage II-III patients. Bioinformatics analysis of CRC tissues and cell lines consistently indicated a correlation between decreased PAICS expression and copy number loss of chromosome arm 4q. In conclusion, our results suggest that PAICS expression is downregulated during tumor progression due to genetic deletion of chromosome 4q in microsatellite stable but chromosomally unstable tumors. Furthermore, decreased expression of PAICS transcript or loss of PAICS protein may provide prognostic stratification for postoperative patients with stage III CRC. [ABSTRACT FROM AUTHOR]

Homeobox A (HOXA) cluster genes, members of the HOX family, perform an important role in normal organ development. It has previously been reported that HOXA gene expression in various types of cancer is associated with poor patient outcomes. However, the role of HOXA genes, as well as their expression, in colorectal cancers (CRC) remains unknown. Therefore, the present study investigated HOXA gene expression in patients with CRC and revealed that HOXA9 expression was significantly increased in tumor tissues compared with non‑tumor tissues. Additionally, the functional role of HOXA9 was assessed by knocking down the HOXA9 gene in CRC cells and by evaluating cell growth. Regarding gene expression, cases with positive HOXA9 expression (as detected by immunohistochemical staining) were significantly associated with higher TNM stage and positive lymph node metastasis, although no association was observed between increased HOXA9 levels and the rate of overall survival in the present cohort. Regarding the functional role, HOXA9 expression was demonstrated to be upregulated in patients with CRC and was associated with lymph node metastasis. [ABSTRACT FROM AUTHOR]

Kinesin family member 4A (KIF4A) is a member of the kinesin 4 subfamily of kinesin-related proteins and serves an important role in cell division. The expression levels of KIF4A have been investigated in numerous types of cancer, including cervical, lung, oral, and breast cancer, and are established to be associated with poor patient prognosis. However, the role of KIF4A, as well as its expression in colorectal cancer (CRC), remains to be elucidated. Therefore, the current study investigated KIF4A expression levels in patients with CRC and demonstrated that its levels were increased in tumor tissues compared with non-tumor tissues. To investigate the functional role of KIF4A, KIF4A was knocked down in CRC cells and cell viability was evaluated. CRC cells with KIF4A knockdown exhibited lower cell proliferation compared with control cells. In addition, KIF4A expression levels, as determined by immunohistochemistry, were compared with the expression of Ki-67, but no significant associations were observed in the patients with CRC. Therefore, KIF4A was found to be upregulated in patients with CRC and downregulation of KIF4A reduced cell proliferation in CRC cells. These results suggest that KIF4A may be a potential therapeutic target, which may improve the outcomes of patients with CRC. [ABSTRACT FROM AUTHOR]

Solute carrier (SLC) drug transporters exchange various molecules without energy from adenosine triphosphate hydrolysis, indicating an association with anticancer drug resistance. However, the expression and role of SLC transporters in malignant tumors has not yet been fully elucidated. Therefore, in the current study, the expression of SLC37A family genes was evaluated in patients with colorectal cancer (CRC), and it was revealed that SLC family 37 member 1 (SLC37A1) expression was significantly increased in tumorous tissues compared with that in non-tumorous tissues. The cases with upregulated expression of SLC37A1 by immunohistochemical staining were significantly associated with positive venous invasion and liver metastasis. Furthermore, upregulated SLC37A1 expression was associated with poor overall survival time in the present cohort. These results indicated that SLC37A1 is involved in the hematogenous metastasis of CRC. To investigate whether SLC37A1 is associated with hematogenous metastasis and glycolipid metabolism, SLC37A1 was knocked down in colon cancer cells, and the expression of sialyl Lewis A and sialyl Lewis X was observed to be decreased. In summary, upregulation of SLC37A1 was observed in patients with CRC, and was associated with poor patient outcomes and survival. To the best of our knowledge, the present study is the first to propose a key role of SLC37A1 in CRC, and additional studies are warranted to reveal the functional role of SLC37A1 in CRC development. [ABSTRACT FROM AUTHOR]

Colorectal cancer (CRC) cells often express Tn antigen, a tumor-associated truncated immature O-glycan (GalNAcα-O-Ser/Thr) that can promote tumor progression. Immunotherapies against Tn antigen have been developed and are being evaluated in clinical trials. Tn antigen can also be considered a novel immune checkpoint that induces immunosuppressive signaling through glycan-biding lectins to lead effector T cell apoptosis. We evaluated the correlation of Tn antigen expression by immunohistochemistry with mismatch-repair (MMR) status, tumor-infiltrating lymphocytes, tumor cell PD-L1 expression, and clinicopathological characteristics in 507 CRC patients. Although 91.9% of CRCs showed negative or weak Tn antigen staining (Tn-negative/weak), we identified a small subset of CRCs (8.1%) that displayed particularly intense and diffuse distribution of Tn antigen immunoreactivity (Tn-strong) that closely related to deficient MMR (dMMR). Moreover, 40 dMMR CRCs were stratified into 24 Tn-negative/weak dMMR tumors (60.0%) exhibiting dense CD8+ lymphocyte infiltrate concomitant with a high rate of PD-L1 positivity, and 16 Tn-strong dMMR tumors (40.0%) that demonstrated CD8+ T cell exclusion and a lack of PD-L1 expression, which was comparable to those of proficient MMR. Our finding suggests that the immune cold subset of patients with Tn-strong dMMR CRC may be effectively treated with immune checkpoint blockade therapy or cellular immunotherapy targeting Tn antigen. [ABSTRACT FROM AUTHOR]