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Protein expression levels in immunohistochemistry and molecular biomarkers have been reported for their ability to predict recurrence, progression, development of metastases, and patient survival. The molecular features in low- and high-grade prostate cancer can differ and influence treatment decision and prognosis. The objective of the current study was to compare the expression of exosomal biomarkers CD63 and mismatch repair proteins (MSH2, MSH6, MLH1, and PMS2) by immunohistochemistry (IHC) in tissue of patients with prostate cancer and benign hyperplasia. Altogether, 62 patients with prostate acinar adenocarcinoma and 20 patients with prostate benign hyperplasia were enrolled in this retrospective study. CD63, MSH2, MSH6, MLH1, and PMS2 expression was analysed by immunohistochemistry. The obtained results showed that CD63 expression was significantly higher in patients with Grade III–V prostate cancer compared to Grade I–II, respectively; 2.23 (1–3) vs 0.92 (0–2) score, p = 0.001. In addition, a significant positive correlation between CD63 expression and grade groups was revealed (Rho = +0.54; p < 0.0001). Furthermore, progression-free survival was significantly higher in patients with low CD63 expression, compared to high CD63 expression (p = 0.0007). MMR expression was absent in 14 patients (four patients with Grade I–II cancer and 10 patients with Grade III–cancer). MMR was present in all cases of benign prostate hyperplasia (mild to moderate staining). The conclusion was that high grade prostate cancer (Grade groups III–V) was characterised by increased CD63 expression, which correlated with progression-free survival.

DNA mismatch repair (MMR) is an essential physiological process for correcting mutations occurring during DNA replication. Deficient MMR (dMMR) leads to increased tumour mutational burden, with a heightened risk of neoplasia. Demonstration of dMMR via the immunohistochemical assessment of MMR proteins is useful when screening for inherited cancer syndromes (especially Lynch syndrome) and for the prediction of clinical cancer response to conventional chemotherapy and novel immunotherapies. Identification of dMMR may also be helpful in other situations e.g. when considering a diagnosis of conventional dysplasia in sessile serrated lesions of the large intestine. This article provides a practical illustrated guide to DNA MMR interpretation, using a series of clinical examples.

The frequency of microsatellite instability (MSI) is reportedly extremely low in breast cancer, despite widespread clinical expectations that many patients would be responsive to immune‐checkpoint inhibitors (ICI). Considering that some triple‐negative breast cancers (TNBC) responded well to ICI in a clinical trial and that a high density of tumor‐infiltrating lymphocytes (TILs) is frequently observed in other cancers with high levels of microsatellite instability (MSI‐H), we hypothesized that some TNBC with a high density of TILs would be MSI‐H. Medullary carcinoma (MedCa) of the breast, a rare histological type, is characterized by a high density of TILs. Considering that MedCa of the colon is often MSI‐H, we suspected that MedCa in breast cancer might also include MSI‐H tumors. Therefore, we conducted MSI tests on such breast cancers with a high density of TILs. The MSI status of 63 TIL‐high TNBC and 38 MedCa tumors, all from Asian women who had undergone curative surgery, were determined retrospectively. DNA mismatch repair (MMR) proteins and PD‐L1 expression were also investigated immunohistochemically. All samples were microsatellite stable, being negative for all microsatellite markers. TIL‐high TNBC with low MLH1 protein had higher levels of PD‐L1 in stromal immune cells (P = .041). MedCa tumors showed significantly higher PD‐L1 expression in immune cells than in TIL‐high TNBC (, We revealed that MSI‐H breast cancers do not correspond to TIL‐high tumors. Furthermore, MLH1 protein expression in triple‐negative breast cancer was inversely correlated with PD‐L1 expression in stromal immune cells. Therefore, we believe that the examination of MMR proteins may merit additional study, as these proteins might provide information for predicting which patients would are likely to benefit from immune‐checkpoint inhibitors.

The relationship between the expression of the SATB2, CDX2, and p53 proteins and common molecular changes in colorectal cancer (CRC) has rarely been studied. Recent literature suggests that the loss of SATB2 and CDX2 expression is more frequently observed in cases of colon cancer with DNA mismatch repair (MMR) protein deficiency and BRAF mutation. We collected 1180 cases of CRC and explored the association between the expression of SATB2, CDX2, and p53 and clinicopathological characteristics and molecular alterations of CRC using whole-slide immunohistochemistry. Our results showed that negative expression of SATB2 and CDX2 was more common in MMR-protein-deficient CRC than in MMR-protein-proficient CRC (15.8% vs. 6.0%, P = 0.001; 14.5% vs. 4.0%, P = 0.000, respectively). Negative expression of SATB2 and CDX2 was more common in BRAF-mutant CRC than in BRAF wild-type CRC (17.2% vs. 6.1%, P = 0.003; 13.8% vs. 4. 2%; P = 0.004, respectively). There was no relationship between SATB2 and/or CDX2 negative expression and KRAS, NRAS, and PIK3CA mutations. The expression of p53 was not associated with MMR protein status or BRAF, KRAS, NRAS and PIK3CA mutations. In addition, the lack of expression of SATB2, CDX2, and p53 was associated with poor histopathological features of CRC. In conclusion, the lack of SATB2 and CDX2 expression in CRC was associated with MMR protein deficiency and BRAF mutation, but not with KRAS, NRAS and PIK3CA mutation. The expression of p53 protein was not related to the common molecular changes of CRC.

Objective: Many familial and sporadic endometrial carcinomas have microsatellite instability (MSI) due to mutations in the DNA mismatch repair (MMR) genes. Immunohistochemistry (IHC) for M...

Background: Colorectal cancer (CRC) with mucinous component is associated with distinct characteristics and controversial prognosis. Patients & methods: A total of 1800 CRC patients were retrospectively enrolled and grouped by the mucinous content of the primary tumors. The clinicopathological characteristics and overall survival rate were compared between groups. Results: Mucinous adenocarcinoma (MAC) and adenocarcinoma with mucinous component (AMC) had higher frequencies of DNA mismatch repair protein deficiency, KRAS, BRAF and PIK3CA mutations as compared to those of conventional adenocarcinoma (CAC). MAC had worse prognosis than CAC. However, MAC was not an independent prognostic factor in multivariable analysis. Conclusion: Molecular features of AMC and MAC were similar, which were different from those of CAC. Neither MAC nor AMC were independent prognostic factors for CRC.

Sebaceous neoplasms with an organoid pattern (rippled, labyrinthine/sinusoidal, carcinoid-like, and petaloid) are rare. Previous studies suggested that the above patterns likely represent variations along a morphological continuum. The objectives of this study were to (1) validate this proposition by studying a large number of cases, (2) determine whether there are specific associations with clinical features, (3) establish their frequency, and (4) determine whether they have any association with Muir-Torre syndrome. Fifty-seven sebaceous neoplasms (54 sebaceomas and 3 sebaceous carcinomas) with organoid growth patterns were studied. These occurred in 36 men and 18 women (sex unknown in 3), with ages at diagnosis ranging from 22 to 89 years (mean, 63 years). All patients presented with a solitary nodule (mean size, 11 mm) on the head and neck area. Of the 57 tumors, 24 manifested a single growth pattern, 23 had a combination of 2 patterns, and 10 a combination of 3 patterns, indicating that these patterns are part of a morphological continuum of changes. The carcinoid-like pattern was the most frequent in the "monopatterned" neoplasms (13 cases), whereas the labyrinthine/sinusoidal pattern comprised most of the "polypatterned" lesions, in which various combinations occurred. Immunohistochemically, mismatch repair protein deficiency was detected in 3 of the 22 cases studied, whereas 5 of the 33 patients with available follow-up had an internal malignancy/premalignancy. In conclusion, sebaceous neoplasms with organoid growth patterns are predominantly sebaceomas having a predilection for the scalp, occurring as solitary lesions in elderly patients (male to female ratio of 2:1). Such patterns are expected to be found in a quarter of sebaceomas. In most cases, more than one of the organoid patterns is present. These lesions do not appear to be associated with internal malignancy or mismatch repair deficiency in most cases. However, confirmation of the absence of any significant association with Muir-Torre syndrome syndrome will require genetic studies.

Interval colorectal cancers may arise from missed or incompletely excised precursors or from a unique rapid progression pathway. We compared the clinicopathologic and molecular profiles of interval and matched non-interval colorectal cancer to determine whether interval colorectal cancers harbor any unique genetic characteristics. Fifty one of 982 colorectal cancer (5.2%) were categorized as interval colorectal cancer, defined as colorectal cancer detected in a diagnostic examination prior to the next recommended colonoscopy and at least 1 year after the last colonoscopy. Clinicopathologic characteristics of interval colorectal cancer were compared to non-interval colorectal cancer matched 1:1 on age, gender, and tumor location. Molecular profile of a subset of interval colorectal cancer (n = 20) and matched (1:2) non-interval colorectal cancer (n = 40) were evaluated using next generation sequencing. Interval colorectal cancer were more likely to occur in the right colon (55% vs. 35%; p = 0.02) and in patients > 70 years of age (55% vs. 34%; p = 0.002). Clinicopathologic features and aberrant DNA mismatch repair protein expression were not significantly different between interval and matched non-interval colorectal cancer. The frequency and spectrum of genetic alterations was also similar in interval and matched non-interval colorectal cancer. Similar findings were seen when analysis was restricted to interval colorectal cancer diagnosed

Purpose Tumor screening for Lynch syndrome is recommended in all or most patients with colorectal cancer (CRC). In metastatic CRC, sequencing of RAS/BRAF is necessary to guide clinical management. We hypothesized that a next-generation sequencing (NGS) panel that identifies RAS/BRAF and other actionable mutations could also reliably identify tumors with DNA mismatch repair protein deficiency (MMR-D) on the basis of increased mutational load. Methods We identified all CRCs that underwent genomic mutation profiling with a custom NGS assay (MSK-IMPACT) between March 2014 and July 2015. Tumor mutational load, with exclusion of copy number changes, was determined for each case and compared with MMR status as determined by routine immunohistochemistry. Results Tumors from 224 patients with unique CRC analyzed for MMR status also underwent MSK-IMPACT. Thirteen percent (n = 28) exhibited MMR-D by immunohistochemistry. Using the 341-gene assay, 100% of the 193 tumors with < 20 mutations were MMR-proficient. Of 31 tumors with ≥ 20 mutations, 28 (90%) were MMR-D. The three remaining tumors were easily identified as being distinct from the MMR-D tumors with > 150 mutations each. Each of these tumors harbored the P286R hotspot POLE mutation consistent with the ultramutator phenotype. Among MMR-D tumors, the median number of mutations was 50 (range, 20 to 90) compared with six (range, 0 to 17) in MMR-proficient/POLE wild-type tumors (P < .001). With a mutational load cutoff of ≥ 20 and < 150 for MMR-D detection, sensitivity and specificity were both 1.0 (95% CI, 0.93 to 1.0). Conclusion A cutoff for mutational load can be identified via multigene NGS tumor profiling, which provides a highly accurate means of screening for MMR-D in the same assay that is used for tumor genotyping.

Lynch syndrome accounts for roughly 1 of every 35 patients with colorectal carcinoma, making it the most common hereditary form of colorectal carcinoma. Identifying patients at risk for Lynch syndrome is essential, as these patients can develop additional Lynch syndrome-related tumors, and patients and their relatives benefit from genetic counseling. The hallmark of Lynch syndrome-associated neoplasms is DNA mismatch repair protein deficiency. In most instances, the pathologist is the first to identify patients at risk for Lynch syndrome and is tasked with communicating these results to treating clinicians and genetics counselors. This review will attempt to provide the tools for pathologists to identify patients at risk for Lynch syndrome through evaluation of tumors of the gastrointestinal tract and provide up-to-date knowledge on evaluating mismatch repair protein deficiency in tumors of the gastrointestinal tract.

Due to several interesting findings on both adaptive survival responses (ASRs) and DNA mismatch repair (MMR), this grant was separated into two discrete Specific Aim sets (each with their own discrete hypotheses). The described experiments were simultaneously performed.

Mutations to proteins involved in DNA mismatch repair (MMR) have been linked to hereditary colorectal cancer. Understanding the mechanism by which these proteins participate in repair (and how these mutations inactivate the repair pathway) is key in furthering our understanding of cancer.We seek to understand the mechanism behind the initiation step of mismatch repair in eukaryotes: binding of MutSα (Msh2 - Msh6) to mismatched DNA. Following mismatch recognition, MutSα then starts a signaling cascade that ultimately leads to repair. Despite knowing that mismatch recognition by MutSα is responsible for initiating repair, the mechanistic steps remain a mystery.We are using single molecule FRET to study the protein:DNA interactions involved in MutSα initiation of MMR. FRET pairs attached to the DNA reveal dynamic bending of DNA by MutSα. In other experiments we want to use single molecule FRET between dyes attached to the damaged DNA and dyes on MutSα - which requires site-specific labeling of the protein. Towards that end, we report progress using unnatural amino acid labeling approaches.