ARL4C is associated with epithelial-to-mesenchymal transition in colorectal cancer

BACKGROUND

ADP-ribosylation factor-like protein 4 C (ARL4C) is a member of the ARF small GTP-binding protein subfamily. The ARL4C gene is highly expressed in colorectal cancer (CRC). ARL4C protein promotes cell motility, invasion, and proliferation.

METHODS

We investigated the characteristics of ARL4C by comparing its expression at the invasion front and relationships with clinicopathological data using RNAscope, a highly sensitive RNA in situ method.

RESULTS

In all cases, ARL4C expression was observed in cancer stromal cells and cancer cells. ARL4C expression in cancer cells was localized at the invasion front. In cancer stromal cells, ARL4C expression was significantly stronger in cases with high-grade tumor budding than in cases with low-grade tumor budding (P = 0.0002). Additionally, ARL4C expression was significantly increased in patients with high histological grade compared with those with low histological grade (P = 0.0227). Furthermore, ARL4C expression was significantly stronger in lesions with the epithelial-to-mesenchymal transition (EMT) phenotype compared with the non-EMT phenotype (P = 0.0289). In CRC cells, ARL4C expression was significantly stronger in cells that had the EMT phenotype compared with those with a non-EMT phenotype (P = 0.0366). ARL4C expression was significantly higher in cancer stromal cells than in CRC cells (P < 0.0001).

CONCLUSION

Our analysis reinforces the possibility that ARL4C expression worsens the prognosis of patients with CRC. Further elucidation of the function of ARL4C is desired.

IgG4 expression and IgG4/IgG ratio in the tumour invasion front predict long-term outcomes for patients with intrahepatic cholangiocarcinoma

IgG4-positive plasma cells are reportedly increased in the tumour microenvironment, and a high number of these cells in tumours is a poor prognostic factor in several cancers. However, there are no reported analyses of IgG4 expression in intrahepatic cholangiocarcinoma (ICC). This study aimed to analyse the correlations between prognosis-related clinicopathological features of patients with ICC and IgG4 expression. We identified 37 ICC patients who underwent surgical resection between January 2010 and December 2020. The number of IgG-positive and IgG4-positive plasma cells in the tumour, invasion front, and stroma near the tumour was analysed by immunostaining. Furthermore, we examined the association of prognosis-related clinicopathological data with the number of IgG4-positive plasma cells and IgG4/IgG ratio in ICC patients. The IgG4-positive plasma cell percentages for the intra-tumour area, invasion front, and non-cancerous area (NCA) near the tumour were 91.9%, 56.8%, and 81.1%, respectively. IgG-positive plasma cells were observed in each region for all cases, except for NCA tissue in one case. A high IgG4 expression level and IgG4/IgG ratio in the invasion front were significantly associated with poor overall survival (OS) (log-rank test p=0.0438 and p=0.0338, respectively). Multivariate analysis for OS revealed that high IgG4 expression (p=0.0140), lymph node metastasis (p=0.0205), and positive surgical margin (p=0.0009) or a high IgG4/IgG ratio (p=0.0051), lymph node metastasis (p=0.0280), and positive surgical margin (p=0.0009) were independent poor prognostic factors. In conclusion, a high IgG4 expression level and IgG4/IgG ratio in the invasion front are independent poor prognostic factors for ICC. Targeted therapy for IgG4 may improve the prognosis for patients with ICC.

LGR5-Expressing Cells in the Healing Process of Post-ESD Ulcers in Gastric Corpus

BACKGROUND

LGR5 is a promising stem cell marker in gastric pylorus, but there are few reports on its expression in human gastric corpus.

AIMS

To investigate the involvement of LGR5 expression in gastric corpus ulcer regeneration in humans.

METHODS

LGR5 expression was analyzed in five post-ESD ulcers during the healing process of regenerating epithelial cells of the gastric corpus. LGR5 expression was detected by mRNA in situ hybridization using an RNA scope kit. Immunohistochemistry of MUC6, HIK1083, and pepsinogen 1 (PG1) was performed to identify cell differentiation.

RESULTS

We defined MUC6+/HIK1083-/PG1-, MUC6+/HIK1083+/PG1-, MUC6+/HIK1083+/PG1+, MUC6+/HIK1083-/PG1+, and MUC6-/HIK1083-/PG1+cells as pseudopyloric mucosa (PPM) phase 1 (PPM1), PPM phase 2 (PPM2), PPM phase 3 (PPM3), immature chief cells (ICC), and mature chief cells (MCC) in order from the ulcer center, respectively. In the regenerated mucosa around post-ESD ulcers, LGR5 expression was observed throughout the gland in PPM1-PPM3, but it was limited to the bottom of the gland in ICC and MCC. Furthermore, LGR5 expression was not identified in the normal gastric corpus. The H-score of PPM2 was significantly higher than that of PPM3 (P = 0.0313). The H-score of PPM3 was significantly higher than that of ICC (P = 0.0313). The LGR5 H-score was higher at the immature stage, which decreased gradually with progression of the differentiation stage.

CONCLUSIONS

LGR5 expression appears to contribute to mucosal regeneration in the human gastric corpus. The application of LGR5 expression analysis to mucosal regeneration and fundic gland-type gastric tumors is expected.

LGR5 expression and clinicopathological features of the invasive front in the fat infiltration area of pancreatic cancer

Background

Leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5) is a strong cancer stem cell marker in colorectal cancer; however, there are many unclear aspects of LGR5 expression in pancreatic cancer. It has been reported that the interaction between tumor cells and stroma at the fat infiltration site has a significant effect on pancreatic cancer prognosis. Therefore, we report a clinicopathological study of LGR5 expression at the fat invasion front in pancreatic cancer.

Methods

LGR5 expression was analyzed in 40 pancreatic ductal adenocarcinoma cases with RNAscope, which is a newly developed high-sensitivity in situ hybridization method. Epithelial-mesenchymal transition (EMT) was analyzed by the expression of E-cadherin and vimentin via immunohistochemistry.

Results

LGR5-positive dots were identified in all cases, especially with glandular formation. In the fat invasion front, a high histological grade showed significantly reduced LGR5 expression compared with a low histological grade (p=0.0126). LGR5 expression was significantly higher in the non-EMT phenotype group than in EMT phenotype group (p=0.0003). Additionally, LGR5 expression was significantly lower in cases with high vascular invasion than in those with low vascular invasion (p=0.0244).

Conclusions

These findings suggest that decreased LGR5 expression in the fat invasion front is associated with more aggressive biological behavior in pancreatic ductal adenocarcinoma, with higher tumor grade, EMT phenotype, and higher vascular invasion.

Impact of DNA double-strand breaks on pancreaticobiliary maljunction carcinogenesis

BACKGROUND

Pancreaticobiliary maljunction (PBM) is a condition characterized by chronic inflammation due to refluxed pancreatic juice into the biliary tract that is associated with an elevated risk of biliary tract cancer. DNA double-strand breaks (DSBs) are considered the most serious form of DNA damage. DSBs are provoked by inflammatory cell damage and are recognized as an important oncogenic event in several cancers. This study used γ-H2AX, an established marker of DSB formation, to evaluate the impact of DNA damage on carcinogenesis in PBM.

METHODS

We investigated γ-H2AX expression immunohistochemically in gallbladder epithelium samples obtained from 71 PBM cases and 19 control cases.

RESULTS

Fourteen PBM cases with gallbladder adenocarcinoma were evaluated at non-neoplastic regions. A wide range of nuclear γ-H2AX staining was detected in all PBM and control specimens. γ-H2AX expression was significantly higher in PBM cases versus controls (median γ-H2AX-positive proportion: 14.4 % vs. 4.4 %, p = 0.001). Among the PBM cases, γ-H2AX expression was significantly higher in patients with carcinoma than in those without (median γ-H2AX-positive proportion: 21.4 % vs. 11.0 %, p = 0.031).

CONCLUSIONS

DSBs occurred significantly more abundantly in the PBM gallbladder mucosa, especially in the context of cancer, indicating an involvement in PBM-related carcinogenesis.

IL-6 expression helps distinguish Castleman's disease from IgG4-related disease in the lung

Background

It is difficult to distinguish between multicentric Castleman’s disease (MCD) and IgG4-related lung disease (IgG4-LD), an IgG4-related disease (IgG4-RD) in the lung.

Methods

We focused on IL-6, which is elevated in MCD, to distinguish between MCD and IgG4-LD by RNAscope, a highly sensitive RNA in situ method. Six cases of MCD and four cases of IgG4-LD were selected.

Results

In all cases of MCD and IgG4-LD, 10 or more IgG4-positive cells were found in one high-power field. All MCD cases were inconsistent with the pathological IgG4-related comprehensive diagnostic criteria, but 2 of 6 cases had an IgG4/IgG ratio greater than 40%. In all IgG4-LD cases, histological features were consistent with the pathological IgG4-RD comprehensive diagnostic criteria. IL-6 expression was observed in all MCD and IgG4-LD cases except for one IgG4-LD biopsy. IL-6-expressing cells were mainly identified in the stroma. Sites of IL-6 expression were not characteristic and were sparse. IL-6 expression tended to be higher in MCD compared with IgG4-LD. A positive correlation was found between the IL-6 H-score and serum IL-6 level.

Conclusion

Differences in IL-6 expression may help distinguish between MCD and IgG4-LD. In addition, the presence of high IL-6 levels may help elucidate the pathological mechanisms of IgG4-LD.

Colitis-associated colorectal adenocarcinomas frequently express claudin 18 isoform 2: implications for claudin 18.2 monoclonal antibody therapy

AIMS

Claudin 18 (CLDN18) is a member of the claudin family of cell surface proteins, which are widely expressed in epithelial cells and play a role in cell-cell adhesion. CLDN18 isoform 2 (CLDN18.2) is specifically expressed in gastric epithelial cells, and is frequently expressed at high levels in gastric adenocarcinoma. On the basis of this, zolbetuximab, a targeted monoclonal antibody, has been developed for patients with CLDN18.2-positive gastro-oesophageal adenocarcinoma. Colitis-associated colorectal adenocarcinomas (CACs) tend to lose intestinal markers and show aberrant gastric mucin expression. Furthermore, clinical trials of human epidermal growth factor receptor 2 (HER2) inhibitor therapy for colorectal carcinoma are ongoing. However, the expression profile of CLDN18.2 and HER2 has not been described in a series of human CACs.

METHODS AND RESULTS

We performed immunohistochemistry for CLDN18 and HER2 on 56 consecutive CACs from 55 inflammatory bowel disease patients, and compared the expression profile with that of a control group of 56 sporadic colorectal adenocarcinomas (CRCs). CLDN18.1 expression and CLDN18.2 expression were validated by reverse transcription polymerase chain reaction (PCR) in paraffin-embedded CRC tissues. CLDN18 was positive in 27% (15/56) of CACs and in 5% (3/56) of sporadic CRCs (P = 0.004), and CLDN18-positive CACs were more likely to have lymph node metastasis than CLDN18-negative CACs (67% versus 36%; P = 0.017). CLDN18 expression was significantly associated with MUC5AC expression (P < 0.001) and loss of special AT-rich sequence-binding protein 2 expression (P = 0.005) in CACs. CLDN18.2 was expressed in CRCs that were immunoreactive for CLDN18. Only 4% of CACs were immunoreactive for HER2, and no differences were identified in sporadic CRCs.

CONCLUSIONS

These findings suggest that certain CAC cases may be candidates for targeted zolbetuximab therapy.

LGR5 expression is associated with prognosis in poorly differentiated gastric adenocarcinoma

Background

Leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5) is an important cancer stem cell marker in gastric cancer. However, no detailed studies are available on LGR5 expression in poorly differentiated gastric adenocarcinoma (PD-AC). Therefore, we investigated the relationship between LGR5 expression and clinicopathological data in PD-AC.

Methods

LGR5 mRNA expression levels were quantified in 41 PD-AC specimens using a highly sensitive RNAscope in situ hybridization technique. Epstein–Barr virus (EBV) infection was also detected by EBV in situ hybridization.

Results

LGR5 expression levels were measured in 38 of 41 PD-AC cases, and 17 cases were identified as LGR5 high. The frequency of EBV positivity tended to be higher in the LGR5-low group than in the LGR5-high group (P = 0.0764). Furthermore, the frequency of vascular invasion tended to be higher in the LGR5-high group than in the LGR5-low group (P = 0.0764). The overall survival of PD-AC patients in the LGR5-high group was significantly lower than in the LGR5-low group (log-rank test, P = 0.0108). The Cox proportional hazard regression model revealed that the LGR5-low group (HR = 0.29; 95% CI: 0.11–0.74; P = 0.01) showed independently better OS for PD-AC.

Conclusions

Quantifying the levels of LGR5 expression may facilitate defining prognosis in Japanese patients with PD-AC. Further study of LGR5 in this context is warranted.

Leucine-rich repeat-containing G-protein-coupled receptor 5 expression and clinicopathological features of colorectal neuroendocrine neoplasms

LGR5 is expressed in various tumors and has been identified as a putative intestinal stem cell marker. Here we investigated LGR5 expression in colorectal neuroendocrine neoplasms and analyzed the correlation with pathological characteristics. We evaluated the clinicopathological features of 8 neuroendocrine tumor (NET) grade 1 (NET G1), 4 NET Grade 2 (NET G2), and 8 NET Grade 3 (NET G3; also termed neuroendocrine carcinoma, or NEC) cases. We examined LGR5 expression using an RNAscope, a newly developed RNA in situ hybridization technique, with a tissue microarray of the neuroendocrine neoplasm samples. LGR5 staining in individual tumor cells was semi-quantitatively scored using an H-score scale. We also performed a combination of LGR5 RNA in situ hybridization and synaptophysin immunohistochemistry. All cases contained tumor cells with some LGR5-positive dots. For all cases, H-scores showed a positive correlation with nuclear beta-catenin expression. In the NEC group, there was a strong positive correlation between H-score and beta-catenin expression. Our findings suggest that LGR5 may serve as a stem cell marker in NEC, as is the case in colon adenocarcinoma. The positive correlation between H-score and beta-catenin expression suggests that LGR5 expression might be affected by beta-catenin expression in neuroendocrine neoplasms and especially in NEC.

Promoter hypomethylation of SKI in autoimmune pancreatitis

The relationship between methylation abnormality and autoimmune pancreatitis (AIP)-a representative IgG4-related disease-has not yet been elucidated. We identified SKI might have a significant methylation abnormality in AIP through methylation array analysis using the Illumina Infinium Human Methylation 450K BeadChip array, and investigated the relationship of SKI with AIP clinicopathological features. The methylation rate of SKI was assessed by quantitative SYBR green methylation-specific PCR, and the degree of SKI expression in tissue specimens was assessed by immunohistochemistry in 10 AIP cases, 14 cases of obstructive pancreatitis area in pancreatic ductal adenocarcinoma (PDA) without a history of AIP, and 9 normal pancreas (NP) cases. The SKI methylation ratio was significantly lower in AIP than in PDA and NP. Additionally, the immunohistochemical staining-index (SI) score for SKI was significantly higher in AIP than NP, although there was no significant difference between AIP and PDA. There was a strong negative correlation between SI score and SKI methylation ratio, and between the serum concentrations of IgG4 and the SKI methylation ratio. There was a moderate positive correlation between the serum concentrations of IgG4 and SI. SKI is thought to be an oncogene indicating that SKI hypomethylation and carcinogenesis might be linked to AIP. Furthermore, the correlation between serum concentrations of IgG4 and SKI methylation levels suggest SKI might be involved in the pathogenesis of AIP. However, the role of SKI has not been clearly elucidated. Further studies are needed to understand further the function of SKI.

Pathological changes of finger and toe in patients with vibration syndrome

Pathological findings of the fingers and toes were studied in finger and toe skin specimens from 21 male patients with vibration syndrome and 13 referent male cadavers. Thickening of the medial muscle layer of small arteries or arterioles, and increase of collagen fibers in the connective tissues, especially in perivascular regions, were noted in not only the finger but also the toe in patients with vibration syndrome. The ratio of the media/external diameter in the finger and toe was significantly greater in the patients than in the referents, even in the patients who had operated chain saws, bush cutters or grinders and had not been exposed to vibration of the foot directly. And the ratio in the finger was approximately parallel with that in the toe in the same subject. The present findings pathohistologically confirmed the existence of circulatory disturbances in the feet as well as the hands. The medial thickening of arteries and perivascular fibrosis in the toe can result from not only direct vibration exposure of the foot, but also long-term repeated vasoconstriction and circulatory disturbances in the foot through the activation of the sympathetic nerve system caused by hand-arm vibration.