Alterations in p53, BRCA1, ATM, PIK3CA, and HER2 genes and their effect in modifying clinicopathological characteristics and overall survival of Bulgarian patients with breast cancer

Familial CCM Genes Might Not Be Main Drivers for Pathogenesis of Sporadic CCMs-Genetic Similarity between Cancers and Vascular Malformations

Cerebral cavernous malformations (CCMs) are abnormally dilated intracranial capillaries that form cerebrovascular lesions with a high risk of hemorrhagic stroke. Recently, several somatic "activating" gain-of-function (GOF) point mutations in PIK3CA (phosphatidylinositol-4, 5-bisphosphate 3-kinase catalytic subunit p110α) were discovered as a dominant mutation in the lesions of sporadic forms of cerebral cavernous malformation (sCCM), raising the possibility that CCMs, like other types of vascular malformations, fall in the PIK3CA-related overgrowth spectrum (PROS). However, this possibility has been challenged with different interpretations. In this review, we will continue our efforts to expound the phenomenon of the coexistence of gain-of-function (GOF) point mutations in the PIK3CA gene and loss-of-function (LOF) mutations in CCM genes in the CCM lesions of sCCM and try to delineate the relationship between mutagenic events with CCM lesions in a temporospatial manner. Since GOF PIK3CA point mutations have been well studied in reproductive cancers, especially breast cancer as a driver oncogene, we will perform a comparative meta-analysis for GOF PIK3CA point mutations in an attempt to demonstrate the genetic similarities shared by both cancers and vascular anomalies.

SHMT2 is Associated with Tumor Purity, CD8+ T Immune Cells Infiltration, and a Novel Therapeutic Target in Four Different Human Cancers

AIMS

This study was launched to identify the SHMT2 associated Human Cancer subtypes.

BACKGROUND

Cancer is the 2nd leading cause of death worldwide. Previous reports revealed the limited involvement of SHMT2 in human cancer. In the current study, we comprehensively analyzed the role of SHMT2 in 24 major subtypes of human cancers using in silico approach and identified a few subtypes that are mainly associated with SHMT2.

OBJECTIVE

We aim to comprehensively analyze the role of SHMT2 in 24 major subtypes of human cancers using in silico approach and identified a few subtypes that are mainly associated with SHMT2. Earlier, limited knowledge exists in the medical literature regarding the involvement of Serine Hydroxymethyltransferase 2 (SHMT2) in human cancer.

METHODS

In the current study, we comprehensively analyzed the role of SHMT2 in 24 major subtypes of human cancers using in silico approach and identified a few subtypes that are mainly associated with SHMT2. Pan-cancer transcriptional expression profiling of SHMT2 was done using UALCAN while further validation was performed using GENT2. For translational profiling of SHMT2, we utilized Human Protein Atlas (HPA) platform. Promoter methylation, genetic alteration, and copy number variations (CNVs) profiles were analyzed through MEXPRESS and cBioPortal. Survival analysis was carried out through Kaplan-Meier (KM) plotter platform. Pathway enrichment analysis of SHMT2 was performed using DAVID, while the gene-drug network was drawn through CTD and Cytoscape. Furthermore, in the tumor microenvironment, a correlation between tumor purity, CD8+ T immune cells infiltration, and SHMT2 expression was accessed using TIMER.

RESULTS

SHMT2 was found overexpressed in 24 different subtypes of human cancers and its overexpression was significantly associated with the reduced Overall survival (OS) and Relapse-free survival durations of Breast cancer (BRCA), Kidney renal papillary cell carcinoma (KIRP), Liver hepatocellular carcinoma (LIHC), and Lung adenocarcinoma (LUAD) patients. This implies that SHMT2 plays a significant role in the development and progression of these cancers. We further noticed that SHMT2 was also up-regulated in BRCA, KIRP, LIHC, and LUAD patients of different clinicopathological features. Pathways enrichment analysis revealed the involvement of SHMT2 enriched genes in five diverse pathways. Furthermore, we also explored some interesting correlations between SHMT2 expression and promoter methylation, genetic alterations, CNVs, tumor purity, and CD8+ T immune cell infiltrates.

CONCLUSION

Our results suggested that overexpressed SHMT2 is correlated with the reduced OS and RFS of the BRCA, KIRP, LIHC, and LUAD patients and can be a potential diagnostic and prognostic biomarker for these cancers.

The prevalence of ataxia telangiectasia mutated (ATM) variants in patients with breast cancer patients: a systematic review and meta-analysis

Breast cancer is the most common cancer in women, and its high mortality has become one of the biggest health problems globally. Several studies have reported an association between breast cancer and ATM gene variants. This study aimed to demonstrate and analyze the relationship between ATM gene polymorphisms and breast cancer prevalence rate. A systematic literature review was undertaken using the following databases: Medline (PubMed), Web of sciences, Scopus, EMBASE, Cochrane, Ovid, and CINHAL to retrieve all cross-sectional studies between January 1990 and January 2020, which had reported the frequency of ATM variants in patients with breast cancer. A random-effects model was applied to calculate the pooled prevalence with a 95% confidence interval. The pooled prevalence of ATM variants in patients with breast cancer was 7% (95% CI: 5−8%). Also, the pooled estimate based on type of variants was 6% (95% CI: 4−8%; I square: 94%; P: 0.00) for total variants¸ 0% (95% CI: 0−1%; I square: 0%; P: 0.59) for deletion variants, 12% (95% CI: 7−18%; I square: 99%; P: 0.00) for substitution variants, and 2% (95% CI: 4−9%; I square: 67%; P: 0.08) for insertion variants. This meta-analysis showed that there is a significant relationship between ATM variants in breast cancer patients. Further studies are required to determine which of the variants of the ATM gene are associated with BRCA mutations.

Characterization of AKT Somatic Mutations in Chinese Breast Cancer Patients

Purpose

This study aimed to investigate AKT gene mutation status in Chinese breast cancer patients.

Methods

The study included 411 breast cancer patients hospitalized in Guangdong Provincial People’s Hospital (GDPH) from June 1, 2017 to September 27, 2018. Mastectomy or breast conserving surgery was performed, and tissue samples were subjected to next-generation sequencing (NGS) to determine AKT gene mutation status. Meanwhile, the expression of human epidermal growth factor receptor 2 (Her2), progesterone receptor (PR), and estrogen receptor (ER) was analyzed by immunohistochemistry staining. The Cancer Genome Atlas (TCGA) database was used for comparative studies.

Results

Patients in the GDPH cohort had an older age (P < 0.001), higher postmenopausal rate (P < 0.001), larger tumor size (P < 0.001), higher histologic type of infiltrating duct cancer (P < 0.001), higher metastatic rate (P < 0.001), higher expression of ER (P = 0.015) and HER2 (P < 0.001), and higher percentage of the HR/HER2 subtype (P < 0.001) than those in the TCGA cohort. The GDPH cohort displayed lower rates of overall AKT and AKT3 mutation (P < 0.001), but a higher AKT1 mutation rate (P < 0.0001) compared with the TCGA cohort. Notably, the NGS studies identified missense mutation and copy number amplification as the most common AKT variation type in the GDPH and TCGA cohorts, respectively. Specifically, E17K mutation in AKT1 was predominantly detected in GDPH cohort, while being absent in TCGA cohort. Moreover, in the GDPH cohort, AKT variation was correlated with a number of clinicopathological variables, including age over 50, HER2-, HR+/HER2-, and PR+.

Conclusion

Patients in the GDPH cohort had lower rates of AKT and AKT3 mutation and higher AKT1 mutation rate than those in the TCGA cohort, while harboring missense mutations detected predominantly as E17K mutation in AKT1. In GDPH cohort, there were correlations between AKT mutation and the clinicopathological characteristics of patients.

Screening for PIK3CA mutations among Saudi women with ovarian cancer

The study aimed to screen for PIK3CA gene mutations among Saudi women with Ovarian Cancer. The study included 298 Saudi women with epithelial ovarian cancers (EOC). DNA sequence analysis was employed to screen for the mutations. DNA sequence analysis of a coding region of exon 9 and 20 of PIK3CA gene revealed mutations in 37/298 (12.4%) EOC patients. About 21/37(56.8%) somatic mutations were identified in exons 9, and 16/37(43.2%) in exon 20. All analysed mutations were missense mutations, the frequencies of which varied from 2.7% to 43.2%. PIK3CA mutation was found to be significantly associated with age (p = .023), grade (p = .001) and histological types (p = .032). Only 6.6% of serous carcinomas and 3.8% of endometrioid had PIK3CA mutation. The Mutated PIK3CA gene was significantly involved in the pathogenesis of EOC among Saudi women. PIK3CA gene mutation and overexpression represent important clinical implications for diagnosis, and prognosis, which can be utilised for better EOC management.Impact statementWhat is already known on this subject? The detailed molecular and genetic phenomenon underlying the progression of these tumours is still unclear. Recently, the pathogenesis of ovarian cancer has been attributed to mutations of PIK3CA.What do the results of this study add? Mutation in the PIK3CA gene leads to altered PI3K/AKT signalling pathways responsible for the progression of the epithelial ovarian cancer.What are the implications of these findings for clinical practice and/or further research? The Mutated PIK3CA gene was significantly involved in the pathogenesis of EOC among Saudi women. PIK3CA gene mutation and overexpression represent important clinical implications for diagnosis, and prognosis, which can be utilised for better EOC management.

Clinicopathological Features and Outcomes in Individuals with Breast Cancer and ATM, CHEK2, or PALB2 Mutations

INTRODUCTION

The moderate-penetrance germline mutations ATM, CHEK2, and PALB2 are implicated in an increased risk of the development of breast cancer. Whether these mutations provide clinical utility to guide treatment strategies and prognosis remains unknown.

METHODS

A retrospective case-control study from a tertiary institution compared patients with stage 0-III breast cancer, and positive for ATM, CHEK2, or PALB2 mutations, with a matched cohort selected by randomization and negative for mutations. Data acquisition included demographics, histopathologic, treatment, and clinical outcome variables.

RESULTS

A total of 145 patients with breast cancer (144 female and 1 male) were analyzed-74 mutation-positive patients (24 ATM, 26 CHEK2, 24 PALB2) and 71 mutation-negative patients. Mutation-positive patients compared with mutation-negative patients had increased family history of breast cancer (79.7 vs. 52.9%, p < 0.001) and tumor size > 2.0 cm (63.1% vs. 42.3%, p = 0.015). Patients with prior knowledge of mutational status were more likely to proceed with total mastectomy and prophylactic mastectomy (74.5% vs. 25.5%, p < 0.02; and 65.5% vs. 34.5%, p < 0.001, respectively). The unadjusted recurrence rate was higher in mutation-positive patients compared with mutation-negative patients (24.3 vs. 8.5%, p = 0.01), although mutation status was not predictive for recurrence in Cox regression analysis.

CONCLUSIONS

Patients positive for ATM, CHEK2, or PALB2 mutations had increased tumor size and were more likely to undergo extensive surgeries. Mutation status was not predictive of recurrence, although this lack of effect may have been mitigated by lower rates of recurrence in those who pursued total mastectomy. Further studies are needed to confirm these findings.

The distinct clinicopathological and prognostic implications of PIK3CA mutations in breast cancer patients from Central China

Purpose

The mutation status and prognostic value of PIK3CA in breast cancer were widely investigated, which showed significant difference among the patients from vast areas around the world. In this study, the frequency, distribution, bias, and burden of PIK3CA mutations and their relationships with clinicopathologic variables and prognostic significances were investigated in the breast cancer patients from Central China.

Materials and methods

Somatic mutations in exon 9 and exon 20 of PIK3CA gene were analyzed using Sanger sequencing combining with targeted next generation sequencing in 494 breast cancer patients from Central China. The correlations between PIK3CA mutations and clinicopathological characteristics and the prognostic values of multiple PIK3CA mutation statuses were evaluated.

Results

PIK3CA mutations were found in 38% of the patients and associated with estrogen receptor-positive, progesterone receptor-positive, low Ki67 labeling index, and luminal/human epidermal growth factor receptor 2-enriched subtypes. Meanwhile, the prognosis of the total patients and the patients in old diagnostic age, progesterone receptor-negative, low Ki67 labeling index, and luminal/human epidermal growth factor receptor 2-enriched subgroups was significantly related to PIK3CA mutations. Most interestingly, the distribution, bias, and burden of PIK3CA mutations were correlated with different clinical, pathological, and molecular features as well as distinct prognostic implications in multiple breast cancer subgroups.

Conclusion

The frequency, distribution, bias, and burden of PIK3CA mutations were associated with various clinical, pathological, and molecular characteristics in the breast cancer patients from Central China. These different mutation statuses can be used as potential indicators of prognosis in multiple breast cancer subgroups.

Systematic identification of mutations and copy number alterations associated with cancer patient prognosis

Successful treatment decisions in cancer depend on the accurate assessment of patient risk. To improve our understanding of the molecular alterations that underlie deadly malignancies, we analyzed the genomic profiles of 17,879 tumors from patients with known outcomes. We find that mutations in almost all cancer driver genes contain remarkably little information on patient prognosis. However, CNAs in these same driver genes harbor significant prognostic power. Focal CNAs are associated with worse outcomes than broad alterations, and CNAs in many driver genes remain prognostic when controlling for stage, grade, TP53 status, and total aneuploidy. By performing a meta-analysis across independent patient cohorts, we identify robust prognostic biomarkers in specific cancer types, and we demonstrate that a subset of these alterations also confer specific therapeutic vulnerabilities. In total, our analysis establishes a comprehensive resource for cancer biomarker identification and underscores the importance of gene copy number profiling in assessing clinical risk.

ATM in breast and brain tumors: a comprehensive review

The ATM gene is mutated in the syndrome, ataxia-telangiectasia (AT), which is characterized by predisposition to cancer. Patients with AT have an elevated risk of breast and brain tumors Carrying mutations in ATM, patients with AT have an elevated risk of breast and brain tumors. An increased frequency of ATM mutations has also been reported in patients with breast and brain tumors; however, the magnitude of this risk remains uncertain. With the exception of a few common mutations, the spectrum of ATM alterations is heterogeneous in diverse populations, and appears to be remarkably dependent on the ethnicity of patients. This review aims to provide an easily accessible summary of common variants in different populations which could be useful in ATM screening programs. In addition, we have summarized previous research on ATM, including its molecular functions. We attempt to demonstrate the significance of ATM in exploration of breast and brain tumors and its potential as a therapeutic target.

Somatic mutations in breast and serous ovarian cancer young patients: a systematic review and meta-analysis

OBJECTIVE

our aim was to evaluate whether somatic mutations in five genes were associated with an early age at presentation of breast cancer (BC) or serous ovarian cancer (SOC).

METHODS

COSMIC database was searched for the five most frequent somatic mutations in BC and SOC. A systematic review of PubMed was performed. Young age for BC and SOC patients was set at ≤ 35 and ≤ 40 years, respectively. Age groups were also classified in < 30 years and every 10 years thereafter.

RESULTS

twenty six (1,980 patients, 111 younger) and 16 studies (598, 41 younger), were analyzed for BC and SOC, respectively. In BC, PIK3CA wild type tumor was associated with early onset, not confirmed in binary regression with estrogen receptor (ER) status. In HER2-negative tumors, there was increased frequency of PIK3CA somatic mutation in older age groups; in ER-positive tumors, there was a trend towards an increased frequency of PIK3CA somatic mutation in older age groups. TP53 somatic mutation was described in 20% of tumors from both younger and older patients; PTEN, CDH1 and GATA3 somatic mutation was investigated only in 16 patients and PTEN mutation was detected in one of them. In SOC, TP53 somatic mutation was rather common, detected in more than 50% of tumors, however, more frequently in older patients.

CONCLUSION

frequency of somatic mutations in specific genes was not associated with early-onset breast cancer. Although very common in patients with serous ovarian cancer diagnosed at all ages, TP53 mutation was more frequently detected in older women.

PI3K mutations in breast cancer: prognostic and therapeutic implications

The PI3K pathway is the most frequently enhanced oncogenic pathway in breast cancer. Among mechanisms of PI3K enhancement, PIK3CA mutations are most frequently (∼30%) observed, along with protein loss of PTEN. Since the first discovery of PIK3CA mutations in solid malignancies in 2004, numerous studies have revealed the prognostic and therapeutic implications of these mutations. Although many issues remain unconfirmed, some have been carved in stone by the level of consistency they have shown among studies: 1) PIK3CA mutations are most likely to be observed in ER-positive/HER2-negative tumors, and are associated with other good prognostic characters; 2) PIK3CA mutations can coexist with other PI3K-enhancing mechanisms, such as HER2 amplification and PTEN protein loss; 3) PIK3CA mutations are potentially a good prognostic marker; 4) PIK3CA may predict a poorer tumor response to trastuzumab-based therapies, but its impact on disease-free survival and overall survival is uncertain; and 5) based on reports of early clinical trials, PIK3CA mutations do not guarantee a dramatic response to PI3K inhibitors. Collectively, there is currently no sufficient evidence to recommend routine genotyping of PIK3CA in clinical practice. Given that PIK3CA-mutant breast cancer appears to have a distinct tumor biology, development of more individualized targeted therapies based on the PIK3CA genotype is awaited.

Deregulation of the EGFR/PI3K/PTEN/Akt/mTORC1 pathway in breast cancer: possibilities for therapeutic intervention

The EGFR/PI3K/PTEN/Akt/mTORC1/GSK-3 pathway plays prominent roles in malignant transformation, prevention of apoptosis, drug resistance and metastasis. The expression of this pathway is frequently altered in breast cancer due to mutations at or aberrant expression of: HER2, ERalpha, BRCA1, BRCA2, EGFR1, PIK3CA, PTEN, TP53, RB as well as other oncogenes and tumor suppressor genes. In some breast cancer cases, mutations at certain components of this pathway (e.g., PIK3CA) are associated with a better prognosis than breast cancers lacking these mutations. The expression of this pathway and upstream HER2 has been associated with breast cancer initiating cells (CICs) and in some cases resistance to treatment. The anti-diabetes drug metformin can suppress the growth of breast CICs and herceptin-resistant HER2+ cells. This review will discuss the importance of the EGFR/PI3K/PTEN/Akt/mTORC1/GSK-3 pathway primarily in breast cancer but will also include relevant examples from other cancer types. The targeting of this pathway will be discussed as well as clinical trials with novel small molecule inhibitors. The targeting of the hormone receptor, HER2 and EGFR1 in breast cancer will be reviewed in association with suppression of the EGFR/PI3K/PTEN/Akt/mTORC1/GSK-3 pathway.

Prognostic role of PIK3CA mutations and their association with hormone receptor expression in breast cancer: a meta-analysis

The phosphatidylinositol-4, 5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA) gene is frequently mutated in breast cancer (BCa). Sex hormone receptors (HRs), including estrogen receptor (ER) and progesterone receptor (PR) play pivotal roles in BCa. In this study, we evaluated the association between PIK3CA mutations and ER/PR expression and the prognostic role of PIK3CA mutations in BCa patients, and in particular, HR-positive BCa. Thirty-two studies involving 5719 cases of BCa obtained from database searches were examined. PIK3CA gene mutations correlated significantly with ER/PR expression (p < 0.00001) and relapse-free survival (RFS) (hazard ratio [HR] 0.76, 95% confidence interval [CI] 0.59-0.98, p = 0.03) but not overall survival (OS) (HR 1.14, 95%CI 0.72-1.82, p = 0.57) in unsorted BCa patients. PIK3CA mutations were not associated with OS (HR 1.06, 95%CI 0.67-1.67, p = 0.81) or RFS (HR 0.86, 95%CI 0.53-1.40, p = 0.55) in HR-positive BCa patients. In conclusion, PIK3CA mutations were significantly related to ER/PR expression and RFS in unsorted BCa patients. However, the clinical implications of PIK3CA mutations may vary according to different mutant exons. And PIK3CA mutations alone may have limited prognostic value for HR-positive BCa patients.

PIK3CA mutations define favorable prognostic biomarkers in operable breast cancer: a systematic review and meta-analysis

Background

Mutations of the p110α catalytic subunit of phosphatidylinositol 3-kinase (PIK3CA) are among the most common genetic aberrations in human breast cancer. At present, controversy exists concerning the prognostic value of the mutations.

Methods

We performed a systematic review and meta-analysis to clarify the association between PIK3CA mutations and survival outcomes. A comprehensive, computerized literature search of PubMed, Web of Science databases, the Chinese Biomedical Literature Database, and Wangfang Data until August 27, 2013 was carried out. Eligible studies were included according to specific inclusion criteria. Pooled hazard ratio was estimated by using the fixed effects model or random effects model according to heterogeneity between studies.

Results

Eight eligible studies were included in the analysis, all of which were retrospective cohort studies. The overall meta-analysis demonstrated that the PIK3CA mutations were associated with better clinical outcomes (hazard ratio 0.72; 95% confidence interval: 0.57–0.91; P=0.006). None of the single studies materially altered the original results and no evidence of publication bias was found. Further subgroup analysis of mutations in exons 9 and 20 did not show statistical significance.

Conclusion

PIK3CA mutations in operable primary breast cancer indicate a good prognosis. Further studies should be conducted to investigate the effect of PIK3CA mutations on clinical outcomes in different histologic types, different molecular subtypes of breast cancer, and different exons of PIK3CA.

Chromogenic in situ hybridization compared with other approaches to evaluate HER2/neu status in breast carcinomas

Human epidermal growth factor receptor 2 (HER2) has been evaluated in breast cancer patients to identify those most likely to benefit from herceptin-targeted therapy. HER2 amplification, detected in 20-30% of invasive breast tumors, is associated with reduced survival and metastasis. The most frequently used technique for evaluating HER2 protein status as a routine procedure is immunohistochemistry (IHC). HER2 copy number alterations have also been evaluated by fluorescence in situ hybridization (FISH) in moderate immunoexpression (IHC 2+) cases. An alternative procedure to evaluate gene amplification is chromogenic in situ hybridization (CISH), which has some advantages over FISH, including the correlation between HER2 status and morphological features. Other methodologies have also been used, such as silver-enhanced in situ hybridization (SISH) and quantitative real-time RT-PCR, to determine the number of HER2 gene copies and expression, respectively. Here we will present a short and comprehensive review of the current advances concerning HER2 evaluation in human breast cancer.

Frequent alterations of MCPH1 and ATM are associated with primary breast carcinoma: clinical and prognostic implications

BACKGROUND

MCPH1 is a proximal regulator of DNA damage response pathway that is involved in recruitment of phosphorylated ATM to double-stranded DNA breaks.

METHODS

To understand the importance of MCPH1 and ATM in deregulation of DNA damage response pathway in breast carcinoma, we studied m-RNA expression and genetic/epigenetic alterations of these genes in primary breast carcinoma samples.

RESULTS

Our study revealed reduced expression (mRNA/protein) and high alterations (deletion/methylation) (96 %, 121 of 126) of MCPH1 and ATM. Mutation was, however, rare in inactivation of MCPH1. In immunohistochemical analysis, reduced protein expression of MCPH1, ATM and p-ATM were concordant with their molecular alterations (P = 0.03-0.01). Alterations of MCPH1 and deletion of ATM were significantly high in estrogen/progesterone receptor-negative than estrogen/progesterone receptor-positive breast carcinoma samples compared to early or late age of onset tumors, indicating differences in pathogenesis of the molecular subtypes (P = 0.004-0.01). These genes also showed differential association with tumor stage, grade and lymph node status in different subtypes of breast carcinoma (P = 0.00001-0.01). Their coalterations showed significant association with tumor progression and prognosis (P = 0.003-0.05). Interestingly, patients with alterations of these genes or MCPH1 alone had poor outcome after treatment with DNA-interacting drugs and/or radiation (P = 0.01-0.05).

CONCLUSIONS

Inactivation of MCPH1-ATM-associated DNA damage response pathway might have an important role in the development of breast carcinoma with diagnostic, prognostic and therapeutic implications.

Phosphatidylinositol-3-kinase pathway mutations are common in breast columnar cell lesions

The phosphatidylinositol-3-kinase pathway is one of the most commonly mutated pathways in invasive breast carcinoma, with PIK3CA mutations in ∼25% of invasive carcinomas, and AKT1 mutations in up to 5%. Ductal carcinoma in situ, and benign papillomas harbor similar mutations. However, activating point mutations in breast columnar cell lesions have been infrequently studied. Twenty-three breast resection specimens containing columnar cell lesions were identified; 14 with associated invasive carcinoma or carcinoma in situ. DNA extracts were prepared from formalin-fixed paraffin-embedded tissue and screened for a panel of point mutations (321 mutations in 30 genes) using a multiplex PCR panel with mass-spectroscopy readout. PIK3CA mutations were identified in 13/24 columnar cell lesions (54%) and 3/8 invasive carcinomas (37%). The mutation status of columnar cell lesions and associated carcinoma was frequently discordant. Of the 14 cases, only 5 demonstrated the same genotype in matched samples of columnar cell lesions and carcinoma (4 wild type, 1 PIK3CA H1047R). Interestingly, five patients had mutations in columnar cell lesions with wild-type carcinoma; two patients had different point mutations in columnar cell lesions and carcinoma. Only three cases had wild-type columnar cell lesion and mutated carcinoma. The 50% PIK3CA mutation prevalence in columnar cell lesions is greater than reported in most studies of invasive breast cancer. Further, columnar cell lesions and carcinoma were frequently discordant for PIK3CA/AKT1 mutation status. These findings raise interesting questions about the role of PIK3CA/AKT pathway in breast carcinogenesis, and the biologic/precursor potential of columnar cell lesions.

Physiological levels of Pik3ca(H1047R) mutation in the mouse mammary gland results in ductal hyperplasia and formation of ERα-positive tumors

PIK3CA, the gene coding for the p110α subunit of phosphoinositide 3-kinase, is frequently mutated in a variety of human tumors including breast cancers. To better understand the role of mutant PIK3CA in the initiation and/or progression of breast cancer, we have generated mice with a conditional knock-in of the common activating mutation, Pik3ca(H1047R), into one allele of the endogenous gene in the mammary gland. These mice developed a ductal anaplasia and hyperplasia by 6 weeks of age characterized by multi-layering of the epithelial lining of the mammary ducts and expansion of the luminal progenitor (Lin(-); CD29(lo); CD24(+); CD61(+)) cell population. The Pik3ca(H1047R) expressing mice eventually develop mammary tumors with 100% penetrance but with a long latency (>12 months). This is significantly longer than has been reported for transgenic models where expression of the mutant Pik3ca is driven by an exogenous promoter. Histological analysis of the tumors formed revealed predominantly ERα-positive fibroadenomas, carcinosarcomas and sarcomas. In vitro induction of Pik3ca(H1047R) in immortalized mammary epithelial cells also resulted in tumor formation when injected into the mammary fat pad of immunodeficient recipient mice. This novel model, which reproduces the scenario of a heterozygous somatic mutation occurring in the endogenous PIK3CA gene, will thus be a valuable tool for investigating the role of Pik3ca(H1047R) mutation in mammary tumorigenesis both in vivo and in vitro.

Associations of miRNA polymorphisms and female physiological characteristics with breast cancer risk in Chinese population

mircoRNAs (miRNAs) play important roles on regulation of gene expressions. Aberrant expression of miRNAs was involved in various biological and pathological processes, including tumorigenesis of breast cancer. Single-nucleotide polymorphisms (SNPs) were implicated in altered expression or biological functions of mature miRNAs. To explore the relevance of miRNA polymorphisms and female physiological characteristics to breast cancer risk, SNPs located within hsa-miR-605 (rs2043556), hsa-miR-149 (rs2292832), hsa-miR-27a (rs895819), hsa-miR-196a-2 (rs11614913) and hsa-miR-618 (rs2682818) were selected, and their associations with breast cancer risk were analysed. In addition, associations between physiological characteristics-related factors and breast cancer risk were estimated too. We found that the ones with menarche age less than 16 years had increased breast cancer risk (OR = 2.10, 95% CI: 1.23-3.60). Marginally significant association between rs11614913 CT/CC genotypes and reduced breast cancer risk was observed (OR = 0.65, 95% CI: 0.40-1.06), while no significance was detected about the other miRNA polymorphisms. We concluded that menarche at less than 16 years old increased breast cancer risk, while the genetic variants in miR-196-a-2 might decrease the risk.

The phosphatidyl inositol 3-kinase/AKT signaling pathway in breast cancer

The phosphatidyl inositol 3-kinase (PI3K)/Akt pathway mediates the effects of a variety of extracellular signals in a number of cellular processes including cell growth, proliferation, and survival. The alteration of integrants of this pathway through mutation of its coding genes increases the activation status of the signaling and can thus lead to cellular transformation. The frequent dysregulation of the PI3K/Akt pathway in breast cancer (BC) and the mediation of this pathway in different processes characteristically implicated in tumorigenesis have attracted the interest of this pathway in BC; however, a more comprehensive understanding of the signaling intricacies is necessary to develop clinical applications of the modulation of this pathway in this pathology. We review a series of experiments examining the contribution of alteration of integrants of this signaling network to human BC and we make an update of the information about the effect of the modulation of this pathway in this cancer.

Reinventing diagnostics for personalized therapy in oncology

Human cancers are still diagnosed and classified using the light microscope. The criteria are based upon morphologic observations by pathologists and tend to be subject to interobserver variation. In preoperative biopsies of non-small cell lung cancers, the diagnostic concordance, even amongst experienced pulmonary pathologists, is no better than a coin-toss. Only 25% of cancer patients, on average, benefit from therapy as most therapies do not account for individual factors that influence response or outcome. Unsuccessful first line therapy costs Canada CAN$1.2 billion for the top 14 cancer types, and this extrapolates to $90 billion globally. The availability of accurate drug selection for personalized therapy could better allocate these precious resources to the right therapies. This wasteful situation is beginning to change with the completion of the human genome sequencing project and with the increasing availability of targeted therapies. Both factors are giving rise to attempts to correlate tumor characteristics and response to specific adjuvant and neoadjuvant therapies. Static cancer classification and grading systems need to be replaced by functional classification systems that not only account for intra- and inter- tumor heterogeneity, but which also allow for the selection of the correct chemotherapeutic compounds for the individual patient. In this review, the examples of lung and breast cancer are used to illustrate the issues to be addressed in the coming years, as well as the emerging technologies that have great promise in enabling personalized therapy.