Mutational Analysis of AKT1 and PIK3CA in Intraductal Papillomas of the Breast with Special Reference to Cellular Components

Radiogenomic Landscape of Metastatic Endocrine-Positive Breast Cancer Resistant to Aromatase Inhibitors

Breast cancer poses a significant global health challenge and includes various subtypes, such as endocrine-positive, HER2-positive, and triple-negative. Endocrine-positive breast cancer, characterized by estrogen and progesterone receptors, is commonly treated with aromatase inhibitors. However, resistance to these inhibitors can hinder patient outcomes due to genetic and epigenetic alterations, mutations in the estrogen receptor 1 gene, and changes in signaling pathways. Radiogenomics combines imaging techniques like MRI and CT scans with genomic profiling methods to identify radiographic biomarkers associated with resistance. This approach enhances our understanding of resistance mechanisms and metastasis patterns, linking them to specific genomic profiles and common metastasis sites like the bone and brain. By integrating radiogenomic data, personalized treatment strategies can be developed, improving predictive and prognostic capabilities. Advancements in imaging and genomic technologies offer promising avenues for enhancing radiogenomic research. A thorough understanding of resistance mechanisms is crucial for developing effective treatment strategies, making radiogenomics a valuable integrative approach in personalized medicine that aims to improve clinical outcomes for patients with metastatic endocrine-positive breast cancer.

Oncogene activated human breast luminal progenitors contribute basally located myoepithelial cells

BACKGROUND

Basal-like breast cancer originates in luminal progenitors, frequently with an altered PI3K pathway, and focally in close association with genetically altered myoepithelial cells at the site of tumor initiation. The exact trajectory behind this bi-lineage phenomenon remains poorly understood.

METHODS AND RESULTS

Here we used a breast cancer relevant transduction protocol including hTERT, shp16, shp53, and PIK3CAH1047R to immortalize FACS isolated luminal cells, and we identified a candidate multipotent progenitor. Specifically, we identified a keratin 23 (K23)+/ALDH1A3+/CALML5- ductal-like progenitor with the potential to differentiate into CALML5+ lobular-like cells. We found that the apparent luminal phenotype of these oncogene transduced progenitors was metastable giving rise to basal-like cells dependent on culture conditions. In 3D organoid culture and upon transplantation to mice the bipotent progenitor cell line organized into a bi-layered acinus-like structure reminiscent of that of the normal breast gland.

CONCLUSIONS

These findings provide proof of principle that progenitors within the human breast luminal epithelial compartment may serve as a source of correctly positioned myoepithelial cells. This may prove useful in assessing the role of myoepithelial cells in breast tumor progression.

Novel Mutations in AKT1 Gene in Prostate Cancer Patients in Jordan

The AKT1 oncogene is related to various cancers due to its critical role in the PIC3CA/AKT1 pathway; however, most of the studies screened the hotspot mutation AKT1 (E17K) with various incidences. Low frequency or lack of AKT1 (E17K) mutation was reported in prostate cancer (PC) patients. This study aims to explore genetic alterations in the AKT1 PH domain by extending the sequencing to include AKT1 gene exons 3 and 4. Genomic DNA was extracted from 84 Formalin-Fixed Paraffin-Embedded samples of PC patients in Jordan, and then subjected to PCR and sequencing for the targeted exons. This study revealed the presence of two novel mutations (N53Y and Q59K) and a high frequency of mutations in exon 4, with a lack of mutations in the E17K hotspot. Nine missense and two synonymous mutations were detected in exon 4 (Phe27Tyr, Phe27Leu, Ala58Thr, Ser56Phe, Arg41Trp, Phe35Leu, Asp32Glu, Phe35Tyr, and Gln43Lys) and (Ser56 and Glu40), respectively. Two synonymous mutations were detected in exon 3 (Leu12 and Ser2). It is concluded that there is a high frequency of AKT1 mutation in PC patients in Jordan with two novel missense mutations in the Pleckstrin homology (PH) domain. E17K hotspot mutation was not detected in any tested samples, which underlined the significant role of mutations in other AKT1 exons in PC development.

Papillary lesions of the breast - review and practical issues

Papillary lesions of the breast represent a heterogeneous group of neoplasm featuring fibrovascular cores covered by epithelial cells with or without intervening myoepithelial cells. According to the World Health Organization classification of breast tumors, papillary lesions of the breast are further classified into intraductal papilloma (including intraductal papilloma with atypical ductal hyperplasia /ductal carcinoma in situ), papillary ductal carcinoma in situ, encapsulated papillary carcinoma, solid papillary carcinoma (in situ and invasive) and invasive papillary carcinoma. The overlapping morphological features and immunohistochemical profiles make accurate diagnosis of breast papillary lesion a challenge for pathologists. In this review, the morphological and relevant immunohistochemical features of papillary lesions are discussed, with further emphasis on some commonly encountered practical diagnostic issues. A simple diagnostic algorithm will be established. The relevant molecular characteristics will be discussed as well.

Myoepithelial progenitors as founder cells of hyperplastic human breast lesions upon PIK3CA transformation

The myoepithelial (MEP) lineage of human breast comprises bipotent and multipotent progenitors in ducts and terminal duct lobular units (TDLUs). We here assess whether this heterogeneity impacts on oncogenic PIK3CA transformation. Single cell RNA sequencing (scRNA-seq) and multicolor imaging reveal that terminal ducts represent the most enriched source of cells with ductal MEP markers including α-smooth muscle actin (α-SMA), keratin K14, K17 and CD200. Furthermore, we find neighboring CD200^high and CD200^low progenitors within terminal ducts. When sorted and kept in ground state conditions, their CD200^low and CD200^high phenotypes are preserved. Upon differentiation, progenitors remain multipotent and bipotent, respectively. Immortalized progenitors are transduced with mutant PIK3CA on an shp53 background. Upon transplantation, CD200^low MEP progenitors distinguish from CD200^high by the formation of multilayered structures with a hyperplastic inner layer of luminal epithelial cells. We suggest a model with spatially distributed MEP progenitors as founder cells of biphasic breast lesions with implications for early detection and prevention strategies.

Breast myoepithelial cells are characterised using single cell sequencing, where they are distinguished by CD200 expression. Distinct properties of CD200-low and CD200-high are found, which suggest that CD200-low cells are multipotent, whereas CD200-high cells are bipotent.

Papillary Neoplasms of the Breast: Diagnostic Features and Molecular Insights

Papillary neoplasms of the breast are a heterogeneous group of tumors characterized by fibrovascular cores lined by epithelium, with or without myoepithelial cells. Papillary neoplasms include benign, atypical, and malignant tumors that show varying histopathologic features and clinical outcomes. Appropriate pathologic classification is crucial to guide clinical treatment. Classification of papillary neoplasms is largely based on morphology, with immunohistochemistry playing an ancillary role to establish diagnoses. Recent molecular studies have provided insight into the genomics of these lesions. This review summarizes the histologic, immunohistochemical, and molecular features of papillary neoplasms of the breast that are important for diagnosis and treatment.

Papillary neoplasms of the breast-reviewing the spectrum

Papillary neoplasms of the breast encompass a wide range of tumor types ranging from the benign intraductal papilloma to in situ and invasive papillary carcinomas. In this review, we considered each tumor entity listed under the Papillary Neoplasms category in the latest WHO Classification of Breast Tumors (5th edition), namely intraductal papilloma, papillary ductal carcinoma in situ, encapsulated papillary carcinoma, solid-papillary carcinoma, and invasive papillary carcinoma. We examined their pathological features, current issues pertaining to diagnosis and prognostication, as well as the latest molecular findings. We also briefly addressed adenomyoepithelioma and the newly included tall cell carcinoma with reversed polarity, highlighting areas where they overlap with papillary neoplasms.

Next-generation sequencing revealed recurrent ZFPM1 mutations in encapsulated papillary carcinoma of the breast

Encapsulated papillary carcinoma (EPC) of the breast is a rare subtype of tumor. To date, the genetic abnormalities underlying EPC remain elusive. The purpose of this study was to gain further insight into EPC mutation profile. Forty-one EPCs diagnosed from 2015 to 2018 were included. Twenty-six EPCs were submitted to whole-exome sequencing (WES), and a 185 gene-targeted sequencing panel was designed to validate the results of the 26 EPCs that underwent WES and 15 additional cases. Recurrently mutated genes were further confirmed by Sanger sequencing. Our study revealed multiple recurrently mutated genes including PI3K-AKT-mTOR pathway genes (PIK3CA, AKT1, ULK1, MAP3K1, MAP2K4, RHOA, and PTEN) (27/41, 65.8%) and chromatin modification genes (ZFPM1, GATA3, CTCF, and KMT2C) (21/41, 51.2%) in EPC. Importantly, somatic ZFPM1 mutations existed in 9/41 (21.9%) of the EPCs. The frequency of ZFPM1 mutations in the EPCs was significantly higher than that of other tumor types. Of the nine ZFPM1 mutations, seven were frameshift mutations, and the remaining two were nonsense mutations. Moreover, a significant concurrence of ZFPM1 and PI3K-AKT-mTOR mutations were revealed in the EPCs. Of note, no TP53 mutations were detected in our EPCs, whereas it was detected in a considerable proportion of the luminal A invasive ductal carcinomas of no special type (IDC-NSTs) from TCGA. We reveal that recurrent somatic ZFPM1 mutation is characteristic of EPC and concurred with mutations in the PI3K-AKT-mTOR pathway. The distinctive genetic features of EPC might underlie its special histological structures and indolent behavior.

Significance of adenosquamous proliferation in breast lesions

Adenosquamous proliferation (ASP), characterised by ductal structures with a dual glandular and squamous phenotype within desmoplastic stroma, is essentially a hallmark of various sclerosing lesions of the breast (SL) and breast lesions with sclerosis (BLWS), not including sclerosing adenosis. In radial scar/complex sclerosing lesion (RS/CSL), clonality has been previously demonstrated in microdissected ASP. SL/BLWS encompass a diverse range of pathological entities that historically have an equally diverse list of names, often for histologically alike or identical lesions at different anatomical locations. In common they are comprised of one or more components of fibrocystic or proliferative breast disease and papillomata, which become distorted and even obliterated by a sclerosing process that appears to be associated with and/or secondary to ASP, which in an individual lesion may be inconspicuous at the time of biopsy. The histological overlap of various SL/BLWS with RS/CSL, in which a nidus containing ASP is pathognomonic of early lesions, also supports a common element of ASP across various SL/BLWS. SL/BLWS show an interesting association with low-grade metaplastic carcinoma, particularly low-grade adenosquamous carcinoma (LGASC) with which, they appear to form a histological and possible biological spectrum because ASP and LGASC share similar histological and immunophenotypical characteristics. The presentation of ASP in various SL/BLWS will be discussed.

Papillary lesions of the breast: a review

Papillary breast lesions are rare breast tumors that comprise a broad spectrum of diseases. Pathologically they present as mass-like projections attached to the wall of the ducts, supported by fibrovascular stalks lined by epithelial cells. On mammogram they appear as masses that can be associated with microcalcifications. Ultrasound is the most used imaging modality. On ultrasound papillary lesions appear as homogeneous solid lesions or complex intracystic lesions. A nonparallel orientation, an echogenic halo or posterior acoustic enhancement associated with microcalcifications are highly suggestive of malignancy. MRI has proven to be useful to establish the extent of the lesion. Core needle biopsy is the gold standard for diagnosis. Surgical excision is usually recommended, although treatment for papillomas without atypia is still controversial.

The Incidence of Adjacent Synchronous Invasive Carcinoma and/or Ductal Carcinoma In Situ in Patients with Intraductal Papilloma without Atypia on Core Biopsy: Results from a Prospective Multi-Institutional Registry (TBCRC 034)

BACKGROUND

Available retrospective data suggest the upgrade rate for intraductal papilloma (IP) without atypia on core biopsy (CB) ranges from 0 to 12%, leading to variation in recommendations. We conducted a prospective multi-institutional trial (TBCRC 034) to determine the upgrade rate to invasive cancer (IC) or ductal carcinoma in situ (DCIS) at excision for asymptomatic IP without atypia on CB.

METHODS

Prospectively identified patients with a CB diagnosis of IP who had consented to excision were included. Discordant cases, including BI-RADS > 4, and those with additional lesions requiring excision were excluded. The primary endpoint was upgrade to IC or DCIS by local pathology review with a predefined rule that an upgrade rate of ≤ 3% would not warrant routine excision. Sample size and confidence intervals were based on exact binomial calculations. Secondary endpoints included diagnostic concordance for IP between local and central pathology review and upgrade rates by central pathology review.

RESULTS

The trial included116 patients (median age 56 years, range 24-82) and the most common imaging abnormality was a mass (n = 91, 78%). Per local review, 2 (1.7%) cases were upgraded to DCIS. In both of these cases central pathology review did not confirm DCIS on excision. Additionally, central pathology review confirmed IP without atypia in core biopsies of 85/116 cases (73%), and both locally upgraded cases were among them.

CONCLUSION

In this prospective study of 116 IPs without atypia on CB, the upgrade rate was 1.7% by local review, suggesting that routine excision is not indicated for IP without atypia on CB with concordant imaging findings.

Effect of AKT1 (p. E17K) Hotspot Mutation on Malignant Tumorigenesis and Prognosis

The substitution of the seventeenth amino acid glutamate by lysine in the homologous structural domain of the Akt1 gene pleckstrin is a somatic cellular mutation found in breast, colorectal, and ovarian cancers, named p. Glu17Lys or E17K. In recent years, a growing number of studies have suggested that this mutation may play a unique role in the development of tumors. In this review article, we describe how AKT1(E17K) mutations stimulate downstream signals that cause cells to emerge transformed; we explore the differential regulation and function of E17K in different physiological and pathological settings; and we also describe the phenomenon that E17K impedes tumor growth by interfering with growth-promoting and chemotherapy-resistant AKT1^lowQCC generation, an intriguing finding that mutants may prolong tumor patient survival by activating feedback mechanisms and disrupting transcription. This review is intended to provide a better understanding of the role of AKT1(E17K) in cancer and to inform the development of AKT1(E17K)-based antitumor strategies.

The genetic architecture of breast papillary lesions as a predictor of progression to carcinoma

Intraductal papillomas (IDP) are challenging breast findings because of their variable risk of progression to malignancy. The molecular events driving IDP development and genomic features of malignant progression are poorly understood. In this study, genome-wide CNA and/or targeted mutation analysis was performed on 44 cases of IDP, of which 20 cases had coexisting ductal carcinoma in situ (DCIS), papillary DCIS or invasive ductal carcinoma (IDC). CNA were rare in pure IDP, but 69% carried an activating PIK3CA mutation. Among the synchronous IDP cases, 55% (11/20) were clonally related to the synchronous DCIS and/or IDC, only one of which had papillary histology. In contrast to pure IDP, PIK3CA mutations were absent from clonal cases. CNAs in any of chromosomes 1, 16 or 11 were significantly enriched in clonal IDP lesions compared to pure and non-clonal IDP. The observation that 55% of IDP are clonal to DCIS/IDC indicates that IDP can be a direct precursor for breast carcinoma, not limited to the papillary type. The absence of PIK3CA mutations and presence of CNAs in IDP could be used clinically to identify patients at high risk of progression to carcinoma.