Genetic and immunohistochemical profiling of small cell and large cell neuroendocrine carcinomas of the breast

The clinicopathological and molecular features of primary high-grade neuroendocrine tumour in the breast

AIMS

Nottingham grade for breast cancers, rather than gastro-entero-pancreatic (GEP) grade for neuroendocrine tumours (NETs), is currently applied to primary breast NETs, which need further clarification. High-grade NETs in breast also remain poorly recognised.

METHODS AND RESULTS

Among 595 breast carcinomas with diffuse synaptophysin (Syn) or chromogranin A (CgA) immunostaining (≥ 90%), 197 eligible cases were selected, including 69 NETs, 123 invasive breast carcinomas of no special type (IBC-NSTs) and five neuroendocrine carcinomas (NECs). The prognostic significance of these two grading systems in breast NETs was assessed. Furthermore, the clinicopathological features were compared in Nottingham G3 cases among three entities. Targeted sequencing and immunostaining (INSM1/p53/Rb/p16) were also performed in all Nottingham G3 NETs, NECs and 10 Nottingham G3 IBC-NSTs. All Nottingham G3 NETs (9 of 69, 13.0%) fell into GEP G3 cases (20 of 69, 29.0%). Nottingham grade provided better prognostic discrimination between G1/G2 and G3 NETs than GEP grade. Among Nottingham G3 cases, there was a trend towards reduced progression-free survival (PFS) in NETs compared with IBC-NSTs (P = 0.057), and the former were more often immunoreactive for INSM1 (44.4 versus 0%, P = 0.033). Nottingham G3 NETs were all of luminal-like phenotype (P < 0.001) and exhibited less aberrant p53 patterns (11.1 versus 80.0%, P = 0.023) as well as more favourable PFS (P = 0.012) and disease-specific survival (P = 0.002) than NECs. Rb loss (4 of 5, 80%), p16 overexpression (5 of 5, 100%) and RB1 mutation (2 of 5, 40%) were observed exclusively in NECs. Based on expression data, epithelial-mesenchymal transition and KRAS signalling pathways were significantly up-regulated in Nottingham G3 NETs (P < 0.05).

CONCLUSIONS

Nottingham grade, rather than GEP grade, holds important prognostic significance in primary breast NETs. Nottingham G3 NETs represent a small proportion of breast NETs, and may demonstrate distinct clinicopathological and molecular features from other high-grade breast carcinomas with diffuse neuroendocrine markers expression.

ZNF703 promotes Triple-Negative breast cancer cell progression and in combination with STK11 predicts disease recurrence (ZS -TNBC Model)

BACKGROUND

It is largely unidentified concerning the underlying genetic causes responsible for triple-negative breast cancers (TNBC), with unpredictable disease recurrence. This study aimed to examine the role of ZNF703 (Zinc finger 703) in the malignant behaviors of TNBC and its role in predicting disease-free survival (DFS).

METHODS

After downregulation of ZNF703 with short interfering RNA (siRNA), we examined the proliferation of TNBC cell line MDA-MB-231 by sulforhodamine B (SRB) assay, the invasion of cells by a transwell invasion model, and the migration of cells by the monolayer wound-healing experiment. mRNA-sequencing data of ZNF703, BRCA1, BRCA2, PALB2, CHEK2, CDH1, PTEN, STK11, ATM, and TP53, and corresponding clinical information were obtained from The Cancer Genome Atlas (TCGA) dataset for a total of 157 stage I-III TNBC samples. The selection of modeling features was executed using the Least Absolute Shrinkage and Selection Operator (LASSO) regression algorithm to avoid model overfitting. The TIMER 2.0 algorithm determined the associations between immune score and gene expressions. Kaplan-Meier analysis was conducted to plot survival analyses.

RESULTS

The aggressive tumor morphology, cell proliferation, cell migration, and cell invasion were partly reversed by the siRNA knockdown of ZNF703 in MDA-MB-231 cells. ZNF703 knockdown markedly enhanced the killing ability of cisplatin These phenomena were verified by another TNBC cell line BT-549. Patients with high expression of ZNF703 had an inferior DFS for TNBC patients at 8 years [Hazard ratio (HR) for high expression vs. low expression was 2.71; 95 %CI, 1.03 to 7.14, P = 0.044]. Receiver Operating Characteristic (ROC) curve was also developed, indicating the area under the curve (AUC) was 0.744 (95 %CI, 0.628 to 0.861) at 5 years and 0.738 (95 %CI, 0.552 to 0.924) at 8 years, respectively. In addition, LASSO regression results showed that the optimal penalization parameter corresponds to two prognostic genes - ZNF703 and STK11. The risk score was computed as Risk Score (RS) = 0.1033*ZNF703 + 0.2131*STK11 (named "ZS -TNBC model"). The high expression of both ZNF703 and STK11 had as high as 7.035 HR in comparison to the low-expression category (95 %CI, 2.044 to 24.206, P = 0.00197).

CONCLUSION

ZNF703 is required for the growth, invasion, and migratory behavior of TNBC cells. Downregulation of ZNF703 increases cisplatin efficacy. This study suggests that either ZNF703 alone or in conjunction with STK11 can be utilized to predict DFS in TNBC.

Primary neuroendocrine tumor of the breast: A case report

Primary neuroendocrine neoplasm of the breast (PNENB) is a rare subtype of breast cancer, accounting for <1% of all breast tumors. The morphological features of PNENB are similar to those of neuroendocrine tumors originating in the lungs or gastrointestinal system, with tumor cells exhibiting the strong expression of neuroendocrine markers, including chromogranin A and synaptophysin. Since this type of cancer was first reported, the definition, classification and diagnostic criteria of PNENB have evolved and changed. However, accurate diagnostic criteria and standard treatment guidelines are lacking. The present report describes a specific case of PNENB, which was consistent with the morphological and molecular features of other cases in most previous studies. In addition, the current body of literature on PNENB, including its development, diagnosis, molecular features, treatment and prognosis is reviewed.

Diagnostic relevance of p53 and Rb status in neuroendocrine tumors G3 from different organs: an immunohistochemical study of 465 high-grade neuroendocrine neoplasms

The double inactivation of TP53 and RB1 is considered typical of neuroendocrine carcinomas (NECs) but is assumed to be rare in high-grade neuroendocrine tumors (NETs). The immunohistochemical determination of the p53 and Rb status has therefore been proposed as a diagnostic tool. We studied this status in a large series of high-grade neuroendocrine neoplasms, from multiple origins, in order to (a) assess the patterns observed in the different histopathological categories, (b) compare them between the various anatomic sites, and (c) evaluate their possible diagnostic relevance. Four hundred sixty-five cases from 9 organ systems (142 high-grade NETs -NET-G3-, 162 large-cell NECs -LCNEC-, 144 small-cell NECs -SCNEC-) and 60 cases of NET G1/G2 were included. The expression of both proteins was normal in 96.7% of NET G1/G2, 76.7% of NET-G3, and 5.8% of all NECs. p53 expression was abnormal in 12.7% of NET-G3 and 91.5% of NECs. Rb expression was lost in 10.6% of NET-G3 and 68.3% of NECs. Rb loss was significantly less frequent in LCNEC than in SCNEC (57.3% versus 80.6%); abnormal p53 expression was comparable in the two categories. Patterns were comparable between primary sites, except for head and neck NECs. For diagnostic purposes, taking into account, Rb status improved, but only marginally, the performances of p53 status. In conclusion, our study underlines the molecular heterogeneity of NET-G3 and LCNEC, irrespectively of the primary, and provides further insight on the diagnostic relevance of p53/Rb immunodetection in high-grade neuroendocrine neoplasms.

Evaluating RB1 and p53 as diagnostic markers in treatment-related neuroendocrine prostate cancer through immunohistochemistry and genomic analysis of RB1 and TP53

BACKGROUND

The diagnosis of treatment-related neuroendocrine prostate cancer (t-NEPC) often involves a pathological assessment and immunohistochemistry (IHC) for neuroendocrine markers. Genomic alterations in RB1 and TP53 are frequently observed in NEPC and are believed to play a crucial role in the transformation of adenocarcinoma to NEPC. In this study, we examined the clinicopathologic, immunohistochemical, and genetic features of patients with t-NEPC to better understand their prognosis and diagnostic utility.

METHODS

This retrospective study reviewed the records of patients diagnosed with t-NEPC at Kobe University Hospital between October 2018 and December 2022. Clinical data, including age, serum neuroendocrine marker levels, and treatment history, were collected. IHC was performed for conventional neuroendocrine markers (synaptophysin, chromogranin A, and CD56) and RB1 and p53 expression. Next-generation sequencing (NGS) was conducted using FoundationOne® CDx to identify mutations in RB1 and TP53.

RESULTS

This study included 20 patients with t-NEPC. The median time from ADT initiation to development was 42.8 months. IHC revealed RB1 loss in 75% of cases and p53 abnormalities in 75% of cases. NGS identified RB1 mutations in 55% and TP53 mutations in 75% of cases. The concordance between NGS and IHC results was high, with 70% (14/20) agreement for RB1/RB1 and 80% (16/20) for p53/TP53. The immunostaining and genomic analysis of RB1/RB1 and p53/TP53 showed abnormal findings for the four negative cases for conventional neuroendocrine markers.

CONCLUSIONS

This study indicated high concordance between IHC and NGS findings for RB1/RB1 and p53/TP53 in t-NEPC. We provide a comprehensive benchmark of NGS performance compared with IHC, and these findings may help increase the diagnostic sensitivity of t-NEPC.

Neuroendocrine Neoplasms of the Breast: Current Insights and Future Directions

BACKGROUND

The breast neuroendocrine neoplasms (NENs) represent a heterogeneous group of tumors and account for less than 1% of all NENs. The 5th edition of the WHO Classification of Breast Tumors in 2019 introduced a more stringent definition for breast NENs including neuroendocrine tumors (NETs) (G1, G2) and neuroendocrine carcinomas (NECs) (small cell carcinoma, large cell neuroendocrine carcinoma). While the diagnostic criteria and treatment of breast NENs still have some unsolved issues.

OBJECTIVE

We aim to discuss the diagnosis, treatment progress, existing problems, and future development direction of breast NENs.

METHODS

We provide a comprehensive review and evaluation of the diagnostic criteria, pathological features, utilization of immunohistochemical markers, molecular characteristics, pathogenesis, clinical significance, treatment options for breast NENs.

RESULTS

(1) Under the new definition, "pure" breast NENs are extremely rare. (2) Breast NETs are graded according to Nottingham grading System. Grading criteria utilized in other systems for NENs, such as mitotic count, ki67 proliferation index, and necrosis, have not been applied to breast NENs. (3) The WHO has not yet acknowledged the existence of NET G3 clearly. (4) The expression of NE markers may differ in breast NECs. (5) The treatment of breast NENs is still based on IBCs-NST, and without any difference from invasive carcinoma with NE features. (6) The prognosis of breast NENs remains unclear, while the prognosis for NECs is significantly poorer than invasive breast carcinomas of no special type (IBCs-NST) has been confirmed.

CONCLUSION

Strict adherence to criteria is the key to correctly diagnose breast NENs with the exclusion of metastasis from other sites. Further exploration is required to determine the tissue origin of breast NENs and understand the pathogenesis. Efforts are still needed to establish unified diagnostic criteria and a unique diagnosis and treatment consensus for breast NENs.

RB1 Genetic Alterations in Estrogen Receptor-Positive Breast Carcinomas: Correlation With Neuroendocrine Differentiation

Genetic alterations in the retinoblastoma susceptibility gene (RB1) are present in up to 40% of triple-negative breast cancers (BCs) and frequent in tumors with neuroendocrine differentiation, including small cell neuroendocrine carcinoma. Data on RB1 genetic alterations in estrogen receptor (ER)-positive BCs are scarce. In this study, we sought to define the morphologic, immunohistochemical, and genetic features of ER-positive BCs harboring somatic alterations in RB1, with emphasis on neuroendocrine differentiation. ER-positive BCs with pathogenic RB1 genetic alterations were identified in <1% of cases (N = 55) from a cohort of 6026 BCs previously subjected to targeted next-generation sequencing, including 23 primary BCs (pBCs) and 32 recurrent/metastatic BCs (mBCs). In cases where loss of heterozygosity of the wild-type RB1 allele could be assessed (93%, 51/55), most pBCs (82%, 18/22) and mBCs (90%, 26/29) exhibited biallelic RB1 inactivation, primarily through loss-of-function mutation and loss of heterozygosity (98%, 43/44). Upon histologic review, a subset of RB1-altered tumors exhibited neuroendocrine morphology (13%, 7/55), which correlated with expression of neuroendocrine markers (39%, 9/23) in both pBCs (27%, 3/11) and mBCs (50%, 6/12). Loss of Rb protein expression was observed in BCs with biallelic RB1 loss only, with similar frequency in pBCs (82%, 9/11) and mBCs (75%, 9/12). All cases with neuroendocrine marker expression (n = 9) and/or neuroendocrine morphology (n = 7) harbored biallelic genetic inactivation of RB1 and exhibited Rb loss of expression. TP53 (53%, 29/55) and PIK3CA (45%, 25/55) were the most frequently comutated genes across the cohort. Overall, these findings suggest that ER-positive BCs with biallelic RB1 genetic alterations frequently exhibit Rb protein loss, which correlates with neuroendocrine differentiation in select BCs. This study provides insights into the molecular and phenotypic heterogeneity of BCs with RB1 genetic inactivation, underscoring the need for further research into the potential clinical implications associated with these tumors.

Defining triple-negative breast cancer with neuroendocrine differentiation (TNBC-NED)

Primary breast neuroendocrine (NE) neoplasms are uncommon, and definitions harbor controversy. We retrospectively collected 73 triple-negative breast cancers (TNBC) and evaluated NE biomarker expression along with p53 aberrant staining (which correlates with TP53 gene mutation) and Rb protein loss by immunohistochemistry. In the study cohort, we found 11 (15%) cases of TNBC with neuroendocrine differentiation (TNBC-NED) showing positivity for one or more NE markers (synaptophysin/chromogranin/insulinoma-associated protein 1 [INSM1]). We also identified one separate small cell neuroendocrine carcinoma. Histologic types for these 11 TNBC-NED cases were as follows: 8 invasive ductal carcinoma (IDC) not otherwise specified (NOS), 2 IDC with apocrine features, 1 IDC with solid papillary features. INSM1 had the highest positivity and was seen in all 11 carcinomas. Seven (64%) cases showed p53 aberrant staining, 6 (55%) had Rb protein loss, while 6 (55%) had p53/Rb co-aberrant staining/protein loss. TNBC-NED was associated with Rb protein loss (p < 0.001), as well as p53/Rb co-aberrant staining/protein loss (p < 0.001). In 61 cases negative for NE markers, 37 (61%) showed p53 aberrant staining, while 5 (8%) had Rb protein loss. We also analyzed genomic and transcriptomic data from The Cancer Genome Atlas (TCGA) PanCancer Atlas of 171 basal/TNBC patients. Transcriptomic analysis revealed mRNA expression of RB1 to be correlated negatively with SYN1 mRNA expression (p = 0.0400) and INSM1 mRNA expression (p = 0.0106) in this cohort. We would like to highlight the importance of these findings. TNBC-NED is currently diagnosed as TNBC, and although it overlaps morphologically with TNBC without NED, the unique p53/Rb signature highlights a genetic overlap with NE carcinomas of the breast.