The Japanese Breast Cancer Society Clinical Practice Guidelines for systemic treatment of breast cancer, 2022 edition.

The Japanese Breast Cancer Society (JBCS) Clinical Practice Guidelines for systemic treatment of breast cancer were updated to the 2022 edition through a process started in 2018. The updated guidelines consist of 12 background questions (BQs), 33 clinical questions (CQs), and 20 future research questions (FRQs). Multiple outcomes including efficacy and safety were selected in each CQ, and then quantitative and qualitative systematic reviews were conducted to determine the strength of evidence and strength of recommendation, which was finally determined through a voting process among designated committee members. Here, we describe eight selected CQs as important updates from the previous guidelines, including novel practice-changing updates, and recommendations based on evidence that has emerged specifically from Japanese clinical trials.

Neurofibroma with adenosis in the mammary gland: a case report.

BACKGROUND: Neurofibroma of the breast is extremely rare, with only a few reported cases. Here, we report a case of solitary neurofibroma of the breast in a 95-year-old woman. CASE PRESENTATION: A 95-year-old woman presented with a palpable mass in the left breast. Mammography revealed a well-defined mass. A 1.6-cm round mass was found in the lower outer quadrant of the left breast on ultrasonography. The internal echo of the tumor was a mixture of relatively uniform hypoechoic areas with posterior enhancement and heterogeneous hyperechoic areas. She underwent a core needle biopsy. The pathological findings revealed a spindle cell lesion with no malignant findings. At 2 months follow-up, repeat breast ultrasonography showed that the mass had enlarged to be 2.7 cm in size. A repeat core needle biopsy, however, revealed no particularly new information. Because the tumor was growing and a definite diagnosis was not made, lumpectomy was performed. We found bland-spindled cells with shredded-carrot collagen bundles. Immunohistochemical antibody markers (S100, SOX10, and CD34) were positive for the spindle cells. Some of the tumors maintained the bilayer nature of luminal cells and myoepithelial cells, which might be the reason for internal heterogeneity on ultrasound. A histological diagnosis of neurofibroma with adenosis was made. At 6 months follow-up, no recurrent lesions were found. CONCLUSIONS: Ultrasound and pathological images revealed an extremely rare case of neurofibroma combined with adenosis. Tumor resection was performed because it was difficult to make a definitive diagnosis using needle biopsy. Even when a benign tumor is suspected, short-term follow-up is necessary, and if an enlargement is observed, early tumor resection is recommended.

Lipidomics-based tissue heterogeneity in specimens of luminal breast cancer revealed by clustering analysis of mass spectrometry imaging: A preliminary study.

Cancer tissues reflect a greater number of pathological characteristics of cancer compared to cancer cells, so the evaluation of cancer tissues can be effective in determining cancer treatment strategies. Mass spectrometry imaging (MSI) can evaluate cancer tissues and even identify molecules while preserving spatial information. Cluster analysis of cancer tissues' MSI data is currently used to evaluate the phenotype heterogeneity of the tissues. Interestingly, it has been reported that phenotype heterogeneity does not always coincide with genotype heterogeneity in HER2-positive breast cancer. We thus investigated the phenotype heterogeneity of luminal breast cancer, which is generally known to have few gene mutations. As a result, we identified phenotype heterogeneity based on lipidomics in luminal breast cancer tissues. Clusters were composed of phosphatidylcholine (PC), triglycerides (TG), phosphatidylethanolamine, sphingomyelin, and ceramide. It was found that mainly the proportion of PC and TG correlated with the proportion of cancer and stroma on HE images. Furthermore, the number of carbons in these lipid class varied from cluster to cluster. This was consistent with the fact that enzymes that synthesize long-chain fatty acids are increased through cancer metabolism. It was then thought that clusters containing PCs with high carbon counts might reflect high malignancy. These results indicate that lipidomics-based phenotype heterogeneity could potentially be used to classify cancer for which genetic analysis alone is insufficient for classification.

Ubiquitin-like 3 as a new protein-sorting factor for small extracellular vesicles.

Ubiquitin-like 3 (UBL3) is a well-conserved ubiquitin-like protein (UBL) in eukaryotes and regulates the ubiquitin cascade, but the significant roles of UBL3 in cellular processes remained unknown. Recently, UBL3 was elucidated to be a post-translational modification factor that promotes protein sorting to small extracellular vesicles (sEVs). Proteins sorted into sEVs have been studied as etiologies of sEV-related diseases. Also, there have been attempts to construct drug delivery systems (DDSs) by loading proteins into sEVs. In this review, we introduce the new concept that UBL3 has a critical role in the protein-sorting system and compare structure conservation between UBL3 and other UBLs from an evolutionary perspective. We conclude with future perspectives for the utility of UBL3 in sEV-related diseases and DDS.Key words: UBL3, small extracellular vesicles, protein sorting, ubiquitin-like protein, post-translational modification.

A difficult-to-diagnose fibromatosis-like metaplastic carcinoma of the breast: a case report.

BACKGROUND: Fibromatosis-like metaplastic carcinoma (FLMCa), classified as a metaplastic carcinoma of the breast, is a very rare type of metaplastic carcinoma. We report a case of FLMCa that was difficult to diagnose. CASE PRESENTATION: The patient was a 56-year-old postmenopausal woman who presented with a left-sided breast mass. A 1.3-cm irregular mass was found in the lower outer quadrant of the left breast on breast ultrasonography. She underwent core needle biopsy and vacuum-assisted biopsy, but the pathological findings only revealed inflammatory cell infiltration and a high level of fibrosis, with no malignant findings. At 3 months follow-up, she underwent a repeat breast ultrasonography, which revealed an increase in the size of the mass to 1.8 cm, and a repeat core needle biopsy, which showed a few spindle cells and squamous cells positive for cytokeratin (CK)5/6 and AE1/AE3, leading to the suspicion of FLMCa. Since the amount of tissue was insufficient to establish a definitive diagnosis, she underwent a lumpectomy. We found low-grade and slightly atypical spindle cells and partly atypical spindle cell carcinoma and squamous cell carcinoma. CK5/6 and α-SMA were positive, thus confirming FLMCa. Because the margins on the edge of the nipple side and anterior side were "ink on tumor", she underwent a mastectomy and sentinel lymph node biopsy. After the surgery, she received adjuvant chemotherapy. At 3 years and 8 months of follow-up, no recurrent or metastatic lesions were identified in her body. CONCLUSIONS: FLMCa should be considered in the differential diagnosis when collagenous fibers are proliferating and malignancy is clinically suspected. Immunohistochemical analysis may be helpful in confirming this diagnosis.

Correction to: Trastuzumab, pertuzumab, and eribulin mesylate versus trastuzumab, pertuzumab, and a taxane as a first-line or second-line treatment for HER2-positive, locally advanced or metastatic breast cancer: study protocol for a randomized controlled, non-inferiority, phase III trial in Japan (JBCRG-M06/EMERALD).

An amendment to this paper has been published and can be accessed via the original article.

Trastuzumab, pertuzumab, and eribulin mesylate versus trastuzumab, pertuzumab, and a taxane as a first-line or second-line treatment for HER2-positive, locally advanced or metastatic breast cancer: study protocol for a randomized controlled, non-inferiority, phase III trial in Japan (JBCRG-M06/EMERALD).

BACKGROUND: Trastuzumab (Tmab), pertuzumab (Pmab), and taxane has been a standard first-line treatment for recurrent or metastatic human epidermal growth factor (HER2)-positive breast cancer (HER2+ mBC) but has some safety issues due to taxane-induced toxicities. This has led to ongoing efforts to seek less toxic alternatives to taxanes that are equally effective when used in combination with Tmab plus Pmab. This study aims to show the non-inferiority of eribulin, a non-taxane microtubule inhibitor, against taxane, as a partner for dual HER2 blockade. METHODS/DESIGN: This multicenter, randomized, open-label, parallel-group, phase III study will involve a total of 480 Japanese women with HER2+ mBC who meet the following requirements: (1) age 20-70 years; (2) no prior cytotoxic chemotherapy (excluding trastuzumab-emtansine) for mBC; (3) ≥ 6 months after prior neoadjuvant or adjuvant cytotoxic chemotherapy; (4) presence of any radiologically evaluable lesion; (5) left ventricular ejection fraction ≥ 50%; (6) Eastern Cooperative Oncology Group performance status score of 0 or 1; (7) adequate organ function; and (8) life expectancy of at least 6 months. They will be randomized 1:1 to receive eribulin (1.4 mg/m2 on days 1 and 8) or taxane (docetaxel 75 mg/m2 on day 1 or paclitaxel 80 mg/m2 on days 1, 8, and 15) in combination with Tmab (8 mg/kg then 6 mg/kg) plus Pmab (840 mg then 420 mg) on day 1 of each 21-day cycle. The treatment will be continued until disease progression or unmanageable toxicity. The primary endpoint is progression-free survival as per investigator according to RECIST v1.1 criteria. Key secondary endpoints include objective response rate, overall survival, quality of life and safety. Non-inferiority will be tested with two margins of 1.33 and 1.25 in a stepwise manner. If non-inferiority is shown with a margin of 1.25, superiority will then be tested. DISCUSSION: If this study shows the non-inferiority, or even superiority, of Tmab, Pmab, and eribulin against the existing taxane-containing regimen, this new regimen may become a standard first- or second-line treatment option for HER2+ mBC in Japan. TRIAL REGISTRATION: ClinicalTrials.gov, ID: NCT03264547. Registered on 28 June 2017.

The Japanese Breast Cancer Society Clinical Practice Guidelines for systemic treatment of breast cancer, 2018 edition.

PURPOSE: We present the English version of The Japanese Breast Cancer Society (JBCS) Clinical Practice Guidelines for systemic treatment of breast cancer, 2018 edition. METHODS: The JBCS formed a task force to update the JBCS Clinical Practice Guidelines, 2015 edition, according to Minds Handbook for Clinical Practice Guideline Development 2014. First, we set multiple outcomes for each clinical question (CQ). Next, quantitative or qualitative systematic review was conducted for each of the multiple outcomes, and the strength of recommendation for the CQ was taken into consideration during meetings, with the aim of finding a balance between benefit and harm. Finalized recommendations from each session were confirmed through discussion and voting at the recommendation decision meeting. RESULTS: The recommendations, the strength of recommendation and the strength of evidence were determined based on systemic literature reviews and the meta-analyses for each CQ. CONCLUSION: The JBCS updated the Clinical Practice Guidelines for systemic treatment of breast cancer.

Preoperative concurrent endocrine therapy with chemotherapy in luminal B-like breast cancer.

PURPOSE: Luminal B-like breast cancer is sensitive to both chemotherapy and endocrine therapy. We aimed to assess the safety and efficacy of concomitant chemotherapy and endocrine therapy compared with chemotherapy alone in the preoperative setting in luminal B-like breast cancer. METHODS: This two-arm randomized clinical trial enrolled patients with luminal B-like human epithelial growth factor 2-negative breast cancer, who were randomly assigned at a 1:1 ratio to receive preoperative chemotherapy alone or preoperative endocrine therapy concurrent with chemotherapy for 24 weeks before surgery. The primary endpoint was the pathological complete response (pCR) rate. The secondary endpoints included the clinical response rate, toxicity, and health-related quality of life (HRQOL). RESULTS: Overall, 70 patients were randomly assigned to the chemotherapy and chemo-endocrine therapy groups. The pCR rates were 9.7% and 3.0% (P = 0.319), and the clinical complete response rates were 5.9% and 5.6% (P = 0.745) in the chemotherapy and chemo-endocrine therapy groups, respectively. There were no clear differences in treatment-related adverse events or HRQOL between the two groups. CONCLUSIONS: In patients with luminal B-like breast cancer, the pCR, clinical response rate, toxicity, and HRQOL with the concomitant administration of endocrine therapy and chemotherapy were not superior to chemotherapy alone in the preoperative setting.

Dose-dense adjuvant chemotherapy: a systematic review and meta-analysis of the Japanese Breast Cancer Society Clinical Practice Guideline, 2018 edition.

Increasing the dose intensity of cytotoxic therapy by shortening the intervals between cycles may enhance efficacy. Dose-dense chemotherapy, which is adopted as adjuvant chemotherapy of high-risk breast cancer, is addressed in the Japanese Breast Cancer Society Clinical Practice Guideline for breast cancer, 2018 edition (in Japanese). To evaluate the benefits and safety of dose-dense adjuvant chemotherapy described in the guideline, we performed a systematic review and meta-analysis of data of randomized trials using the same drugs, doses, and numbers of cycles. The PubMed, Cochrane Library, and Ichushi-Web databases were searched for relevant publications reporting randomized trials published until November 2016. Overall survival (OS), disease-free survival (DFS), and toxicity were assessed. Three trials comprising 5190 patients were included. Compared with conventional chemotherapy, dose-dense chemotherapy lengthened OS (RR = 0.76; 95% CI = 0.64-0.90) and DFS (RR = 0.83; 95% CI = 0.75-0.92) and increased the risk of anemia (RR = 4.56; 95% CI = 2.01-10.34). We conclude that dose-dense chemotherapy can be highly recommended as adjuvant chemotherapy for patients with breast cancer with a high risk of recurrence risk and sufficient bone marrow function.

Efficacy of denosumab for restoring normal bone mineral density in women receiving adjuvant aromatase inhibitors for early breast cancer.

BACKGROUND: Osteoporosis is a major side effect of aromatase inhibitors (AIs), which are greatly effective in the treatment of breast cancer. However, there are no satisfactory measures against osteoporosis. In this multicenter, randomized, comparative study, we evaluate the efficacy of denosumab for preventing loss of bone mineral density (BMD) induced by adjuvant therapy with AI s in breast cancer patients with normal BMD. PATIENTS AND METHODS: The bone loss-suppressing effect of denosumab will be comparatively evaluated in postmenopausal patients scheduled to receive letrozole or anastrozole as a postoperative endocrine therapy for stage I-IIIA hormone-sensitive breast cancer and a control group. Patients will be administered letrozole 2.5 mg or anastrozole 1 mg once a day, and the treatment will be continued for 5 years unless recurrence, secondary cancer, or unacceptable toxicity develops. Patients in the denosumab group will receive a subcutaneous injection of 60 mg of denosumab every 6 months. The primary endpoint is the rate of change in the lumbar spine (L1-L4) BMD, as determined by dual-energy X-ray absorptiometry (DXA), 12 months after the start of the injection. The secondary endpoints were ETHICS AND DISSEMINATION:: The protocol was approved by the institutional review boards of Kyoto Prefectural University of Medicine and all the participating faculties. Written informed consent was obtained from all patients before registration, in accordance with the Declaration of Helsinki. Results of the study will be disseminated via publications in peer-reviewed journals. TRIAL REGISTRATION: Clinical Trials.gov Identifier: NCT03324932, Japan Registry of Clinical Trial (jRCT): CRB5180001.

Effect of denosumab on low bone mineral density in postmenopausal Japanese women receiving adjuvant aromatase inhibitors for non-metastatic breast cancer: 24-month results.

BACKGROUND: Aromatase inhibitors (AI) have been established as the gold-standard therapy for postmenopausal patients. Worldwide, adjuvant denosumab at a dose of 60 mg twice per year reduces the risk of clinical fractures in postmenopausal patients with breast cancer who received AI. However, the efficacy of denosumab in the treatment of AI-associated bone loss had not been prospectively evaluated in Japan. Previously, we reported the 12-month effect of denosumab in Japanese patients for the first time; the primary endpoint was the change in the percentage of bone mineral density (BMD) of the lumbar spine from baseline to 12 months. METHODS: This secondary follow-up study prospectively evaluated the change in the percentage of BMD of the lumbar spine from baseline to 24 months. Postmenopausal women with early-stage, histologically confirmed, hormone receptor-positive, invasive breast cancer who were receiving or scheduled to receive AI were included. Denosumab was administered subcutaneously on day 1 of the study and then 6, 12, 18, and 24 months. The lumbar spine and bilateral femoral neck BMD was measured at baseline and 6, 12, 18, and 24 months. RESULTS: At 18 and 24 months, the lumbar spine BMD increased by 5.9 and 7.0%, respectively. The femoral neck BMD also increased. Grade ≥ 2 hypocalcemia, osteonecrosis of the jaw, and atypical femoral fractures did not occur. CONCLUSIONS: Our prospective study showed that semiannual treatment with denosumab was associated with continuously increased BMD in Japanese women receiving adjuvant AI therapy for up to 24 months, regardless of prior AI treatment.

Two cases of diabetic mastopathy: MR imaging and pathological correlation.

Diabetic mastopathy is a rare benign condition associated with long-standing diabetes mellitus and presents with breast lumps. This report describes two cases in which diffusion-weighted images (DWI) on magnetic resonance imaging were quite different from each other. In case 1, there were hyperintense lesions on DWI, and surgically removed specimens revealed ductitis with marked lymphocytic infiltration. In case 2, no abnormal intensity was depicted on DWI, and biopsy specimens showed dense stromal fibrosis with mild perivascular lymphocytic infiltration that corresponded to previous reports. Although it is reported that diabetic mastopathy is composed of dense fibrous tissue with low cellularity that results in no hyperintense lesion on DWI, in cases with marked lymphocytic infiltration, strong hyperintensity can be seen on DWI mimicking malignant breast tumors.

DNA methylation alterations of AXIN2 in serrated adenomas and colon carcinomas with microsatellite instability.

BACKGROUND: Recent work led to recognize sessile serrated adenomas (SSA) as precursor to many of the sporadic colorectal cancers with microsatellite instability (MSI). However, comprehensive analyses of DNA methylation in SSA and MSI cancer have not been conducted. METHODS: With an array-based methylation sensitive amplified fragment length polymorphism (MS-AFLP) method we analyzed 8 tubular (TA) and 19 serrated (SSA) adenomas, and 14 carcinomas with (MSI) and 12 without (MSS) microsatellite instability. MS-AFLP array can survey relative differences in methylation between normal and tumor tissues of 9,654 DNA fragments containing all NotI sequences in the human genome. RESULTS: Unsupervised clustering analysis of the genome-wide hypermethylation alterations revealed no major differences between or within these groups of benign and malignant tumors regardless of their location in intergenic, intragenic, promoter, or 3' end regions. Hypomethylation was less frequent in SSAs compared with MSI or MSS carcinomas. Analysis of variance of DNA methylation between these four subgroups identified 56 probes differentially altered. The hierarchical tree of this subset of probes revealed two distinct clusters: Group 1, mostly composed by TAs and MSS cancers with KRAS mutations; and Group 2 with BRAF mutations, which consisted of cancers with MSI and MLH1 methylation (Group 2A), and SSAs without MLH1 methylation (Group 2B). AXIN2, which cooperates with APC and ß-catenin in Wnt signaling, had more methylation alterations in Group 2, and its expression levels negatively correlated with methylation determined by bisulfite sequencing. Within group 2B, low and high AXIN2 expression levels correlated significantly with differences in size (P = 0.01) location (P = 0.05) and crypt architecture (P = 0.01). CONCLUSIONS: Somatic methylation alterations of AXIN2, associated with changes in its expression, stratify SSAs according to some clinico-pathological differences. We conclude that hypermethylation of MLH1, when occurs in an adenoma cell with BRAF oncogenic mutational activation, drives the pathway for MSI cancer by providing the cells with a mutator phenotype. AXIN2 inactivation may contribute to this tumorigenic pathway either by mutator phenotype driven frameshift mutations or by epigenetic deregulation contemporary with the unfolding of the mutator phenotype.

Increased polyamine intake inhibits age-associated alteration in global DNA methylation and 1,2-dimethylhydrazine-induced tumorigenesis.

Polyamines (spermine and spermidine) play many important roles in cellular function and are supplied from the intestinal lumen. We have shown that continuous high polyamine intake inhibits age-associated pathologies in mice. The mechanism by which polyamines elicit these effects was examined. Twenty-four week old Jc1:ICR male mice were fed one of three experimental chows containing different polyamine concentrations. Lifetime intake of high polyamine chow, which had a polyamine content approximately three times higher than regular chow, elevated polyamine concentrations in whole blood, suppressed age-associated increases in pro-inflammatory status, decreased age-associated pathological changes, inhibited age-associated global alteration in DNA methylation status and reduced the mortality in aged mice. Exogenous spermine augmented DNA methyltransferase activity in Jurkat and HT-29 cells and inhibited polyamine deficiency-induced global alteration in DNA methylation status in vitro. In addition, increased polyamine intake was associated with a decreased incidence of colon tumors in BALB/c mice after 1,2-demethylhydrazine administration; 12 mice (60%) in the low polyamine group developed tumors, compared with only 5 mice (25%) in the high polyamine group (Fisher's exact probability = 0.027, p = 0.025). However, increased polyamine intake accelerated the growth of established tumors; maximal tumor diameter in the Low and High groups was 3.85±0.90 mm and 5.50±1.93 mm, respectively (Mann-Whitney test, p = 0.039). Spermine seems to play important roles in inhibiting age-associated and polyamine-deficient induced abnormal gene methylation as well as pathological changes including tumorigenesis.

Human breast cancer tissues contain abundant phosphatidylcholine(36∶1) with high stearoyl-CoA desaturase-1 expression.

Breast cancer is the leading cause of cancer and mortality in women worldwide. Recent studies have argued that there is a close relationship between lipid synthesis and cancer progression because some enzymes related to lipid synthesis are overexpressed in breast cancer tissues. However, lipid distribution in breast cancer tissues has not been investigated. We aimed to visualize phosphatidylcholines (PCs) and lysoPCs (LPCs) in human breast cancer tissues by performing matrix assisted laser desorption/ionization-imaging mass spectrometry (MALDI-IMS), which is a novel technique that enables the visualization of molecules comprehensively. Twenty-nine breast tissue samples were obtained during surgery and subjected to MALDI-IMS analysis. We evaluated the heterogeneity of the distribution of PCs and LPCs on the tissues. Three species [PC(32∶1), PC(34∶1), and PC(36∶1)] of PCs with 1 mono-unsaturated fatty acid chain and 1 saturated fatty acid chain (MUFA-PCs) and one [PC(34∶0)] of PCs with 2 saturated fatty acid chains (SFA-PC) were relatively localized in cancerous areas rather than the rest of the sections (named reference area). In addition, the LPCs did not show any biased distribution. The relative amounts of PC(36∶1) compared to PC(36∶0) and that of PC(36∶1) to LPC(18∶0) were significantly higher in the cancerous areas. The protein expression of stearoyl-CoA desaturase-1 (SCD1), which is a synthetic enzyme of MUFA, showed accumulation in the cancerous areas as observed by the results of immunohistochemical staining. The ratios were further analyzed considering the differences in expressions of the estrogen receptor (ER), human epidermal growth factor receptor 2 (HER2), and Ki67. The ratios of the signal intensity of PC(34:1) to that of PC(34:0) was higher in the lesions with positive ER expression [corrected]. The contribution of SCD1 and other enzymes to the formation of the observed phospholipid composition is discussed.

The accumulation of DNA demethylation in Sat α in normal gastric tissues with Helicobacter pylori infection renders susceptibility to gastric cancer in some individuals.

Helicobacter pylori (HP) infection is widely recognized as a risk factor for gastric cancer, but only a minority of infected individuals develop gastric cancer. The aim of this study was to determine whether DNA demethylation in non-cancerous gastric mucosa (NGM) significantly enhances susceptibility to gastric cancer. A total of 165 healthy volunteers, including 83 HP-positive and 82-negative individuals, as well as 83 patients with single and 18 with synchronous double gastric cancer (GC) were enrolled in this study. The relative demethylation levels (RDLs) of repetitive sequences, including Alu, LINE-1 and Sat α, were quantified by real-time methylation-specific polymerase chain reaction. The Alu RDL did not exhibit any differences within each respective group, whereas LINE-1 RDL was significantly elevated in cancer tissues compared with the NGM in the other groups (P<0.001). Our results indicated that a gradual increase in Sat α RDL correlated with HP infection and cancer development. Sat α RDL was significantly elevated in the NGM in HP-positive compared with HP-negative (P<0.001), and significantly elevated in cancer tissues (P<0.001). Although the Sat α RDL of the NGM in the total population increased in an age-dependent manner, it was significantly increased in a fraction of younger GC patients (<45 years) compared with all of the others (45 years or older, P=0.0391). In addition, double GC exhibited a significantly higher Sat α RDL in the NGM compared with single GC (P=0.0014). In these two fractions, Sat α RDL in the NGM exhibited an inverse correlation with age. In conclusion, the present study demonstrated that the accumulation of DNA demethylation in Sat α RDL in the NGM with HP infection potentially renders susceptibility to gastric cancer in a fraction of GC patients younger than 45 years or in patients with multiple cancers.

Aberrant methylation of the Pleckstrin and Sec7 domain-containing gene is implicated in ulcerative colitis-associated carcinogenesis through its inhibitory effect on apoptosis.

The Pleckstrin and Sec7 domain-containing (PSD) gene, which regulates skeletal rearrangements, has been found to be more frequently methylated both in ulcerative colitis (UC)-associated colorectal cancer tissues (5 of 7; 71.4%) and matched normal epithelia (4 of 7; 57.1%) compared to non-neoplastic UC epithelia (6 of 22; 27.3%) and sporadic colorectal cancer tissues (6 of 32; 18.8%). The levels of PSD mRNA were positively correlated with the methylation status of PSD, as shown by both MSP and bisulfite sequencing. To determine the potential role of PSD silencing in the mechanisms underlying UC-associated carcinogenesis, the levels of senescence, proliferation and apoptosis were evaluated in a normal human fibroblast cell line (NHDF) in which 93% of PSD expression was knocked down by a small-interfering RNA (si-RNA). Although there were no significant differences in the levels of senescence and proliferation caused by PSD knockdown, the level of apoptosis was significantly decreased by PSD knockdown (5.3% in siControl-treated cells vs. 0.67% in siPSD-treated cells, p=0.0001). In addition, reactive oxygen species inducers accelerated apoptosis in NHDF and a neutrophil-like cell line, which was significantly reduced by PSD knockdown. To verify the effect of PSD methylation in tissue sections including 21 samples from UC patients with or without tumors, we elucidated PSD promoting accumulation of filamentous-actin (F-actin) and apoptosis by immunohistochemistry and TUNEL assay, respectively. Both levels of accumulation of F-actin and apoptosis were significantly decreased in specimens from UC patients with PSD methylation compared to those without PSD methylation (F-actin: 0.69±0.86 with vs. 1.57±0.51 without, p=0.0031, apoptotic index: 0.31±0.63 with vs. 1.0±0.88 without, p=0.0277). In conclusion, our results indicate that PSD methylation plays a significant role in the mechanisms underlying UC-associated carcinogenesis through its inhibitory effect on apoptosis in the interaction between colorectal mucosa and neutrophils.

Aberrant methylation of PSD disturbs Rac1-mediated immune responses governing neutrophil chemotaxis and apoptosis in ulcerative colitis-associated carcinogenesis.

We previously reported that the Pleckstrin and Sec7 domain-containing (PSD) gene is preferentially methylated in patients with ulcerative colitis (UC) who developed colorectal cancer (CRC), and is implicated in UC-associated carcinogenesis through its inhibition of apoptosis. This study aimed to determine the potential effect of PSD methylation on its downstream molecule, Ras-related C3 botulinum toxin substrate 1 (Rac1), which governs neutrophil chemotaxis and apoptosis signaling. PSD was knocked down in a normal human fibroblast cell line (HNDF) and a neutrophil-like cell line (HL-60). Both NHDF and HL-60 cells exhibited numerous filamentous-actin (F-actin) rich membrane extensions, resulting in the activation of Rac1; this activation was hampered by PSD silencing. Lipopolysaccharide, a reactive oxygen species (ROS) inducer, stimulated NHDF cells to release ROS and activated caspase­3/7 in the presence of neutrophils, which was inhibited by PSD knockdown. Migration assays demonstrated that chemotaxis of HL-60 cells was affected by PSD silencing in NHDF cells. Tissue sections from 6 UC patients with CRC and 15 UC patients without CRC were examined. To verify Rac1-mediated chemotaxis in tissue sections, we evaluated the grade of neutrophil infiltration by histological assessment and assessed F-actin and PSD expression by immunohistochemistry. Neutrophil infiltration, F-actin and PSD expression were significantly decreased in specimens from UC patients with PSD methylation compared with those without. Decreased levels of F-actin expression were observed in colorectal mucosa, as well as in infiltrating cells with PSD methylation. PSD expression was preferentially inhibited in colorectal mucosa by PSD methylation, whereas PSD expression was rarely observed in infiltrating cells, regardless of PSD methylation status. These data indicate that aberrant methylation of PSD occurs in UC-associated colorectal mucosa, enabling circumvention of Rac1-mediated immune responses governing neutrophil chemotaxis and apoptosis, and thus plays a pivotal role in the mechanisms underlying UC-associated carcinogenesis.