Heterogeneity of genomic profile in patients with HER2-positive breast cancer

CDK12 is a potential biomarker for diagnosis, prognosis and immunomodulation in pan-cancer

Cell cycle-dependent protein kinase 12 (CDK12) plays a key role in a variety of carcinogenesis processes and represents a promising therapeutic target for cancer treatment. However, to date, there have been no systematic studies addressing its diagnostic, prognostic and immunological value across cancers. Here, we found that CDK12 was significantly upregulated in various types of cancers, and it expression increased with progression in ten cancer types, including breast cancer, cholangiocarcinoma and colon adenocarcinoma. Moreover, the ROC curves indicated that CDK12 showed diagnostic value in eight cancer types. High CDK12 expression was associated with poor prognosis in eight types of cancer, including low-grade glioma, mesothelioma, melanoma and pancreatic cancer. Furthermore, we conducted immunoassays to explore the exact mechanisms underlying CDK12-induced carcinogenesis, which revealed that increased expression of CDK12 allowed tumours to evade immune surveillance and upregulate immune checkpoint genes. Additionally, mutational studies have shown that amplification and missense mutations are the predominant mutational events affecting CDK12 across cancers. These findings establish CDK12 as a significant biological indicator of cancer diagnosis, prognosis, and immunotherapeutic targeting. Early surveillance and employment of CDK12 inhibitors, along with concomitant immunotherapy interventions, may enhance the clinical outcomes of cancer patients.

Inhibition of the Cyclin K-CDK12 complex induces DNA damage and increases the effect of androgen deprivation therapy in prostate cancer

Androgen deprivation therapy (ADT) is the mainstay of the current first-line treatment concepts for patients with advanced prostate carcinoma (PCa). However, due to treatment failure and recurrence investigation of new targeted therapeutics is urgently needed. In this study, we investigated the suitability of the Cyclin K-CDK12 complex as a novel therapeutic approach in PCa using the new covalent CDK12/13 inhibitor THZ531. Here we show that THZ531 impairs cellular proliferation, induces apoptosis, and decreases the expression of selected DNA repair genes in PCa cell lines, which is associated with an increasing extent of DNA damage. Furthermore, combination of THZ531 and ADT leads to an increase in these anti-tumoral effects in androgen-sensitive PCa cells. The anti-proliferative and pro-apoptotic activity of THZ531 in combination with ADT was validated in an ex vivo PCa tissue culture model. In a retrospective immunohistochemical analysis of 300 clinical tissue samples we show that Cyclin K (CycK) but not CDK12 expression correlates with a more aggressive type of PCa. In conclusion, this study demonstrates the clinical relevance of the CycK-CDK12 complex as a promising target for combinational therapy with ADT in PCa and its importance as a prognostic biomarker for patients with PCa.

Somatic mutations in a multigene panel and impact on prognosis based on TP53 status in Chinese HER2-positive patients undergoing neoadjuvant therapy: A single-institution retrospective cohort

BACKGROUND

Gene mutations play a crucial role in the occurrence and development of tumors, particularly in breast cancer (BC). Neoadjuvant therapy (NAT) has shown greater clinical benefit in HER2-positive breast cancer. However, further clinical investigation is needed to fully understand the correlation between genetic mutations and NAT efficacy and the long-term prognosis in HER2-positive BC.

METHODS

This was a retrospective cohort study of 222 patients receiving NAT between 2017 and 2021 in the Department of Breast Surgery of Fudan University Shanghai Cancer Center. Tumor samples from these patients were subjected to Next Generation Sequencing (NGS) to analyze mutations in 513 cancer-related genes. This study aimed to investigate the association between these genetic mutations and postoperative pathological complete response (pCR), as well as their impact on disease-free survival (DFS).

RESULTS

In total, 48.65% patients reached pCR, ER-negative status (p < 0.001), PR-negative status (p < 0.001), Ki67 ≥ 20 (p = 0.011), and dual-targeted therapy (p < 0.001) were all associated with enhanced pCR rates. The frequency of somatic alterations in TP53 (60%), PIK3CA (15%), and ERBB2 (11%) was highest. In the HER2+/HR- cohort, patients who achieved pCR had a significant benefit in prognosis (HR = 3.049, p = 0.0498). KMT2C (p = 0.036) and TP53 (p = 0.037) mutations were significantly increased in patients with DFS events. Moreover, TP53 mutations had prognostic significance in HER2-positive BC patients with HR-negative (HR = 3.712, p = 0.027) and pCR (HR = 6.253, p = 0.027) status and who received herceptin-only targeted therapy (HR = 4.145, p = 0.011).

CONCLUSIONS

The genetic mutation profiles of Chinese HER2+ patients who received NAT were discrepant with respect to HR status or DFS events. TP53 mutations have significant prognostic value in patients with NAT for HER2-positive BC and patients benefit differently depending on HR status, the neoadjuvant regimen and response, which highlights the significance of genetic factors in treatment customization based on individual genetic and clinical characteristics.

Genetic and clinical landscape of ER + /PR- breast cancer in China

BACKGROUND

Estrogen receptor-positive and progesterone receptor-negative (ER + /PR-) breast cancer comprise a special type. More than 10% breast cancer patients belonged to ER + /PR-.

METHODS

In order to better understand this patient population, we utilized a unique dataset from China, examining the clinicopathological features and genomic profiles of ER + /PR- breast cancers. Our study involved three cohorts: Cohort 1 included 2120 unselected ER-positive female patients with re-evaluated clinicopathological and survival data; Cohort 2 comprised 442 ER-positive females who underwent genetic testing; and Cohort 3 consisted of 77 ER-positive/HER2-negative females tested with MammaPrint and BluePrint.

RESULTS

Patients were stratified into four categories based on the PR/ER ratio. Clinically, ER + /PR- tumors (PR/ER ratio = 0) showed the lowest proportion of T1 tumors (10.88%) and highest proportion of HER2-positive tumors (28.36%) than did other ER + /PR + tumors groups. The ER + /PR- group contained a higher number of underweight patients (20.20%). Independently of HER2 status, ER + /PR- patients demonstrated the poorest prognosis. Genomically, the most prevalent mutations were PIK3CA (50%) in ER + /PR + tumors and TP53 (65%) in ER + /PR- tumors. ER + /PR- tumors presented more frequent mutations in TP53, ERBB2, CDK12, SPEN, and NEB, with mutation rates of 65%, 42%, 27%, 13%, and 10%, respectively. Additionally, the Tumor Mutational Burden (TMB) was higher in the ER + /PR- group compared to the ER + /PR + group. The MammaPrint score for the ER + /PR-/HER2- group was significantly lower than that of other groups. In the BluePrint analysis, only four patients were classified as Basal-Type, all of whom were ER + /PR-/HER2-.

CONCLUSIONS

In this study, we identified the clinical and genetic characteristics of ER + /PR- breast cancer patients in China. Distinct PR statuses indicated different biological processes of ER + breast cancer and survival outcomes. Future treatment strategies may need to be tailored for ER + /PR- patients.

Research progress of anticancer drugs targeting CDK12

Cyclin-dependent kinase 12 (CDK12) is a transcription-associated CDK that plays key roles in transcription, translation, mRNA splicing, the cell cycle, and DNA damage repair. Research has identified that high expression of CDK12 in organs such as the breast, stomach, and uterus can lead to HER2-positive breast cancer, gastric cancer and cervical cancer. Inhibiting high expression of CDK12 suppresses tumor growth and proliferation, suggesting that it is both a biomarker for cancer and a potential target for cancer therapy. CDK12 inhibitors can competitively bind the CDK12 hydrophobic pocket with ATP to avoid CDK12 phosphorylation, blocking subsequent signaling pathways. The development of CDK12 inhibitors is challenging due to the high homology of CDK12 with other CDKs. This review summarizes the research progress of CDK12 inhibitors, their mechanism of action and the structure-activity relationship, providing new insights into the design of CDK12 selective inhibitors.

Genomic analysis of plasma circulating tumor DNA in patients with heavily pretreated HER2 + metastatic breast cancer

We explored accumulated genomic alterations in patients with heavily treated HER2 + metastatic breast cancer enrolled in the KCSG BR18-14/KM10B trial. Targeted sequencing was performed with circulating tumor DNAs (ctDNAs) collected before the treatment of 92 patients. ctDNAs collected at the time of disease progression from seven patients who had a durable response for > 12 months were also analyzed. Sixty-five genes were identified as pathogenic alterations in 99 samples. The most frequently altered genes were TP53 (n = 48), PIKCA (n = 21) and ERBB3 (n = 19). TP53 and PIK3CA mutations were significantly related with shorter progression free survival (PFS), and patients with a higher ctDNA fraction showed a worse PFS. The frequency of homologous recombination deficiency (HRD)-related gene mutations was higher than that in matched tumor tissues, and these mutations tended to be associated with shorter PFS. New pathogenic variants were found at the end of treatment in all seven patients, including BRCA2, VHL, RAD50, RB1, BRIP1, ATM, FANCA, and PIK3CA mutations. In conclusion, TP53 and PIK3CA mutations, as well as a higher ctDNA fraction, were associated with worse PFS with trastuzumab and cytotoxic chemotherapy. The enrichment of HRD-related gene mutations and newly detected variants in ctDNA may be related to resistance to treatment.

Metformin and HER2-positive breast cancer: Mechanisms and therapeutic implications

Due to the strong association between diabetes and cancer incidents, several anti-diabetic drugs, including metformin, have been examined for their anticancer activity. Metformin is a biguanide antihyperglycemic agent used as a first-line drug for type II diabetes mellitus. It exhibits anticancer activity by impacting different molecular pathways, such as AMP-inducible protein kinase (AMPK)-dependent and AMPK-independent pathways. Additionally, Metformin indirectly inhibits IGF-1R signaling, which is highly activated in breast malignancy. On the other hand, breast cancer is one of the major causes of cancer-related morbidity and mortality worldwide, where the human epidermal growth factor receptor-positive (HER2-positive) subtype is one of the most aggressive ones with a high rate of lymph node metastasis. In this review, we summarize the association between diabetes and human cancer, listing recent evidence of metformin's anticancer activity. A special focus is dedicated to HER2-positive breast cancer with regards to the interaction between HER2 and IGF-1R. Then, we discuss combination therapy strategies of metformin and other anti-diabetic drugs in HER2-positive breast cancer.

Transcription-associated cyclin-dependent kinase 12 (CDK12) as a potential target for cancer therapy

Cyclin-dependent kinase 12 (CDK12), a transcription-related cyclin dependent kinase (CDK), plays a momentous part in multitudinous biological functions, such as replication, transcription initiation to elongation and termination, precursor mRNA (pre-mRNA) splicing, intron polyadenylation (IPA), and translation. CDK12 can act as a tumour suppressor or oncogene in disparate cellular environments, and its dysregulation likely provokes tumorigenesis. A comprehensive understanding of CDK12 will tremendously facilitate the exploitation of novel tactics for the treatment and precaution of cancer. Currently, CDK12 inhibitors are nonspecific and nonselective, which profoundly hinders the pharmacological target validation and drug exploitation process. Herein, we summarize the newly comprehension of the biological functions of CDK12 with a focus on recently emerged advancements of CDK12-associated therapeutic approaches in cancers.

A gene expression signature in HER2+ breast cancer patients related to neoadjuvant chemotherapy resistance, overall survival, and disease-free survival

Breast cancer ranks first in terms of mortality and incidence rates worldwide among women. The HER2+ molecular subtype is one of the most aggressive subtypes; its treatment includes neoadjuvant chemotherapy and the use of a HER2 antibody. Some patients develop resistance despite positive results obtained using this therapeutic strategy. Objective. To identify prognostic markers for treatment and survival in HER2+ patients. Methods. Patients treated with neoadjuvant chemotherapy were assigned to sensitive and resistant groups based on their treatment response. Differentially expressed genes (DEGs) were identified using RNA-seq analysis. KEGG pathway, gene ontology, and interactome analyses were performed for all DEGs. An enrichment analysis Gene set enrichment analysis was performed. All DEGs were analyzed for overall (OS) and disease-free survival (DFS). Results. A total of 94 DEGs were related to treatment resistance. Survival analysis showed that 12 genes (ATF6B, DHRS13, DIRAS1, ERAL1, GRIN2B, L1CAM, IRX3, PRTFDC1, PBX2, S100B, SLC9A3R2, and TNXB) were good predictors of disease-free survival, and eight genes (GNG4, IL22RA2, MICA, S100B, SERPINF2, HLA-A, DIRAS1, and TNXB) were good predictors of overall survival (OS). Conclusion: We highlighted a molecular expression signature that can differentiate the treatment response, overall survival, and DFS of patients with HER2+ breast cancer.

Distinct clinical and somatic mutational features of breast tumors with high-, low-, or non-expressing human epidermal growth factor receptor 2 status

BACKGROUND

HER2-low breast cancers were reported to have distinct clinicopathological characteristics from HER2-zero; however, the difference in their genetic features remains unclear. This study investigated the clinical and molecular features of breast tumors according to HER2 status.

METHODS

We analyzed the clinicopathological and genomic data of 523 Chinese women with breast cancer. Genomic data was generated by targeted next-generation sequencing (NGS) of breast tumor samples using a commercial 520 gene panel. The cohort was stratified according to HER2 status as HER2-zero (n = 90), HER2-low (n = 231), and HER2-positive (n = 202) according to their immunohistochemistry and fluorescence in situ hybridization results.

RESULTS

HER2-low breast tumors were enriched with hormone receptor-positive tumors, and who had lower Ki67 expression levels. Genes were differentially mutated across HER2 subgroups. HER2-low tumors had significantly more mutations involved in PI3K-Akt signaling than HER2-positive (p < 0.001) and HER2-zero breast tumors (p < 0.01). HER2-zero tumors had more mutations in checkpoint factors (p < 0.01), Fanconi anemia (p < 0.05), and p53 signaling and cell cycle pathway (p < 0.05) compared to HER2-low breast tumors. Compared with HER2-zero tumors, HER2-low tumors had significantly lower pathological complete response rates after neoadjuvant therapy (15.9% vs. 37.5%, p = 0.042) and proportion of relapsed/progressed patients across follow-up time points (p = 0.031), but had comparable disease-free survival (p = 0.271).

CONCLUSION

Our results demonstrate the distinct clinical and molecular features and clinical outcomes of HER2-low breast tumors.

First-in-human HER2-targeted Bispecific Antibody KN026 for the Treatment of Patients with HER2-positive Metastatic Breast Cancer: Results from a Phase I Study

PURPOSE

KN026 is a novel bispecific antibody that simultaneously binds to two distinct HER2 epitopes. This first-in-human phase I study evaluated the safety/tolerability, pharmacokinetics, preliminary efficacy, and potential predictive biomarker activity of KN026 administered as monotherapy to patients with HER2-positive metastatic breast cancer (MBC).

PATIENTS AND METHODS

Female patients with HER2-positive MBC who had progressed on prior anti HER2 therapies received intravenous KN026 monotherapy at 5 mg/kg (once weekly), 10 mg/kg (once weekly), 20 mg/kg (once every 2 weeks), or 30 mg/kg (once every 3 weeks). Dose escalation was guided by a "3+3" dose escalation rule followed by dose expansion.

RESULTS

Sixty-three patients were enrolled. The most common treatment-related adverse events (TRAE) were pyrexia (23.8%), diarrhea (22.2%), aspartate aminotransferase increased (22.2%), alanine aminotransferase increased (22.2%). Only 4 patients reported grade 3 TRAEs. Results from exposure-response analysis supported the selection of the recommended phase II doses at 20 mg/kg once every 2 weeks or 30 mg/kg once every 3 weeks, which had objective response rates (ORR) of 28.1% and median progression-free survival (PFS) of 6.8 months (95% confidence interval: 4.2-8.3) in 57 patients. Translational research in 20 HER2-amplified patients further confirmed that co-amplification (vs. no co-amplification) of CDK12 was a promising biomarker in predicting better response to KN026 (ORR of 50% vs. 0% and median PFS of 8.2 vs. 2.7 months, P = 0.05 and 0.04, respectively).

CONCLUSIONS

KN026, a HER2 bispecific antibody, was well tolerated and achieved comparable efficacy as trastuzumab and pertuzumab doublet even in the more heavily pretreated patients. Co-amplification of HER2/CDK12 may define patients who benefit more from KN026.

Genetic and immune characteristics of sentinel lymph node metastases and multiple lymph node metastases compared to their matched primary breast tumours

BACKGROUND

Patients with breast cancer presenting with single lymph node metastasis (from a sentinel node) experience prolonged survival compared to patients with multiple lymph node metastases (≥3). However, little information is available on the genetic and immunological characteristics of breast cancer metastases within the regional lymph nodes as they progress from the sentinel lymph node (SLN) downstream to multiple regional lymph nodes (MLNs).

METHODS

Genomic profiling was performed using a next-generation sequencing panel covering 520 cancer-related genes in the primary tumour and metastatic lymph nodes of 157 female patients with breast cancer. We included primary tumours, metastatic lymph nodes and adjacent clinically normal lymph nodes (20 patients from the SLN group and 28 patients from the MLNs group) in the whole transcriptome analysis.

FINDINGS

The downstream metastatic lymph nodes (P = 0.029) and the primary breast tumours (P = 0.011) had a higher frequency of PIK3CA mutations compared to the SLN metastasis. We identified a distinct group of 14 mutations from single sentinel node metastasis and a different group of 15 mutations from multiple nodal metastases. Only 4 distinct mutations (PIK3CA, CDK4, NFKBIA and CDKN1B) were conserved in metastases from both lymph node settings. The tumour mutational burden (TMB) was significantly lower in single nodal metastasis compared to the paired primary breast cancer (P = 0.0021), while the decline in TMB did not reach statistical significance in the MLNs group (P = 0.083). In the gene set enrichment analysis, we identified 4 upregulated signatures in both primary tumour and nodal metastases from the MLNs group, including 3 Epithelial-mesenchymal transition(EMT) signatures and 1 angiogenesis signature. Both the CD8/Treg ratio and the CD8/EMT ratio were significantly higher in adjacent normal lymph nodes from patients with a single metastasis in the SLN compared with samples from the MLNs group (P = 0.045 and P = 0.023, respectively). This suggests that the immune defence from the MLNs patients might have a less favourable microenvironment, thus permitting multiple lymph nodes metastasis.

INTERPRETATION

Single lymph node metastases and multiple lymph node metastases have significant differences in their molecular profiles and immune profiles. The findings are associated with more aggressive tumour characteristics and less favourable immune charactoristics in patients with multiple nodal metastases compared to those with a single metastasis in the sentinel node.

FUNDING

This work was supported by funds from High-level Hospital Construction Project (DFJH201921), the National Natural Science Foundation of China (81902828 and 82002928), the Fundamental Research Funds for the Central Universities (y2syD2192230), and the Medical Scientific Research Foundation of Guangdong Province (B2019039).

Integrated analysis of cell cycle-related genes in HR+/HER2- breast cancer

PURPOSE

This study aimed to explore the mutational characteristics and significance of cell cycle-related genes (CCGs) in hormone-receptor positive, human epidermal growth factor receptor 2 negative breast cancer (HR+/HER2- BC).

METHODS

A total of 1668 HR+/HER2- BC patients from the Guangdong Provincial People's Hospital (GDPH) cohort (n = 321) and METABRIC cohort (n = 1347) were included. Tumor samples from HR+/HER2- BC patients were collected for a next-generation sequencing assay in GDPH cohort, including 15 key CCGs. The association between CCGs alterations and overall survival were identified via the Cox regression analysis. The functional roles of the CCGs were explored via the Metascape database.

RESULTS

Based on multivariate Cox regression analysis, a set of five key CCGs (CDK4, CCND1, CDKN1A, CDKN1C, and CHEK2) were identified as independent prognostic variables in HR+/HER2- BC patients. Besides, the five-CCGs-based risk score was used to effectively classify patients into the low-risk and high-risk groups (P < 0.0001). The potential functional pathways of the CCGs included cell cycle, cyclin D associated events in G1, and regulation of G1/S transition of mitotic cell cycle.

CONCLUSION

We performed the integrated analysis of the CCGs in HR+/HER2- BC patients. It has the potential to guide individualized precision oncology therapeutic schemes in HR+/HER2- BC patients.

Mutational Landscape of PI3K-AKT-mTOR Pathway in Breast Cancer: Implications for Targeted Therapeutics

Background: Comprehensive analysis of PI3K-AKT-mTOR pathway gene alterations in breast cancer may be helpful for targeted therapy. Methods: We performed targeted sequencing using a panel of 520 cancer-related genes to investigate gene alterations in the PI3K-AKT-mTOR pathway from 589 consecutive Chinese women diagnosed with stage I-III breast cancer. Analyses of overall survival (OS) were performed using the publicly available clinical and genomic data from METABRIC. Results: PI3K-AKT-mTOR pathway gene alterations were detected in 62.6% (369/589) of our cohort. The most commonly altered genes were PIK3CA (45%), PTEN (7.5%), AKT1 (5.9 %), PIK3R1 (2.7%), and PIK3CG (2%). Four PIK3CA mutations (E545K, H1047R, E542K, and H1047L) were detected in all the breast cancer molecular subtypes. Seven PIK3CA mutations (E545G, E418_L422delinsV, E726K, E110del, G1049R, G118D, and D350G) were only detected in HR+ subtypes. Two PIK3CA mutations (C420R and N345K) were only detected in non-triple-negative subtypes. Most cases with PTEN mutation were HR+/HER2- subtype (77.3%), followed by triple-negative subtype (18.2%). In the METABRIC breast cancer dataset, no significant OS difference was observed between the PIK3CA-mutant and wild-type groups. However, patients with multiple PIK3CA mutations (mOS: 131 vs. 159 months, P= 0.029), or PIK3CA mutations located in the C2 domain had significantly shorter OS (mOS, 130 vs. 154 months, P=0.020) than those without the mutations. Conclusions: Our study reveals the heterogeneity in PI3K-AKT-mTOR pathway among the breast cancer molecular subtypes in our cohort. Moreover, the number and specific sites of PIK3CA mutations have distinct prognostic impact.

Characterization of Frequently Mutated Cancer Genes and Tumor Mutation Burden in Chinese Breast Cancer

Objectives

Various genomic alterations and genomic signatures, including ERBB2 amplification, mutations in PIK3CA, AKT1, and ESR1, and tumor mutational burden (TMB), have become important biomarkers for treatment selection in breast cancer (BC). This study aimed to investigate the mutational features of Chinese early-stage BC patients.

Methods

Tumors and matched blood samples collected from 589 Chinese patients with early-stage BC were sequenced using a commercial gene panel consisting of 520 cancer-related genes to analyze all types of genomic alterations and estimate the TMB status.

Results

A total of 18 genes were found to be more frequently mutated (P<0.05) or amplified (P<0.05) in stage T3-4 tumors as compared with T1-2 tumors. A total of 18 genes were found to be differentially mutated (P<0.05) or amplified (P<0.05) in patients with lymph node metastasis than those without lymph node metastasis. Younger patients (≤35 years) were more frequently identified with mutations or gene amplifications in eleven genes (P<0.05). TMB >10mutations/Mb were found in 5.7% of our cohort. Although the TMB was similar for various molecular subtypes between our cohort and the BC cohort of The Cancer Genome Atlas (TCGA) study, the TMB were statistically different for HR+/HER-, HR+/HER2+, and triple-negative subtypes between our cohort and African Americans in the TCGA study. As compared to the TCGA BC cohort, our cohort had a much earlier median age of diagnosis (48 vs. 58 years, P<0.001), and had significantly lower frequency of triple-negative subtype (11.5% vs. 18.4%, P<0.001) and invasive lobular BC (2.4% vs. 19.0%, P<0.001). Further subgroup analyses revealed that mutation rates in various genes including TP53, ERBB2, and PIK3CA were distinct for patients who were younger (≤35 years), had triple-negative or invasive lobular BC in our cohort than in the TCGA cohort.

Conclusions

This study revealed distinct mutational features of various molecular subtypes of early-stage BC among Chinese patients. Moreover, we provide new insights into the differences in early-stage BC between the East and West.

Association of Body Mass Index With Somatic Mutations in Breast Cancer

Background

The relationship between body mass index (BMI) and the prognosis or treatment response in patients with breast cancer has been demonstrated in previous studies, but the somatic mutation profiles in breast cancer patients with different BMIs have not been explored.

Methods

In the present study, the somatic mutation profiles in 421 female breast cancer patients who were stratified into three subgroups based on BMI (normal weight, overweight/obese, and underweight) were investigated. Capture-based targeted sequencing was performed using a panel comprising 520 cancer-related genes.

Results

A total of 3547 mutations were detected in 390 genes. In breast cancer patients with different BMI statuses, the tumors exhibited high mutation frequency and burden. TP53 was the most common gene in the three groups, followed by PIK3CA, ERBB2, and CDK12. Meanwhile, the mutation hotspots in TP53 and PIK3CA were the same in the three BMI groups. More JAK1 mutations were identified in underweight patients than those in normal patients. Except for JAK1, differentially mutated genes in postmenopausal patients were completely different from those in premenopausal patients. The distribution of mutation types was significantly different among BMI groups in the postmenopausal group. Underweight patients in the postmenopausal group harbored more TP53 mutations, more amplifications, and more mutations in genes involved in the WNT signaling pathway.

Conclusions

Our next-generation sequencing (NGS)-based gene panel analysis revealed the gene expression profiles of breast cancer patients with different BMI statuses. Although genes with high mutation frequency and burden were found in different BMI groups, some subtle differences could not be ignored. JAK1 mutations might play a vital role in the progression of breast cancer in underweight patients, and this needs further analysis. Postmenopausal underweight patients with breast cancer have more aggressive characteristics, such as TP53 mutations, more amplifications, and more mutations in genes involved in the WNT signaling pathway. This study provides new evidence for understanding the characteristics of breast cancer patients with different BMIs.

PARPBP is a prognostic marker and confers anthracycline resistance to breast cancer

BACKGROUND

PARPBP (PARP1 binding protein) is an important suppressor of homologous recombination during DNA repair, but the expression and function of PARPBP in breast cancer remain unclear.

METHODS

PARPBP expression was analyzed in breast cancer patient samples and public datasets for its correlation with clinical outcome. The function of PARPBP in breast cancer cell proliferation and anthracycline treatment response were studied both in vitro and in vivo.

RESULTS

PARPBP was upregulated significantly at both mRNA and protein levels in breast cancer tissues compared with normal breast tissues. PARPBP high expression group had poorer overall survival (OS) than the PARPBP low expression group. Knockdown of PARPBP suppressed breast cancer cell proliferation and colony formation while overexpression of PARPBP did the opposite. We found that transcription factor forkhead box M1 (FOXM1) could activate PARPBP expression by directly binding to the promoter of PARPBP. In addition, high expression of PARPBP related with anthracycline resistance in breast cancer. Depletion of PARPBP increased breast cancer cell apoptosis and DNA damage caused by epirubicin. Moreover, tumor xenograft experiments further demonstrated that PARPBP was involved in breast cancer anthracycline resistance.

CONCLUSION

Taken together, our results highlight that PARPBP is a prognostic marker and confers anthracycline resistance on breast cancer.

Targeting DNA Damage Response in Prostate and Breast Cancer

Steroid hormone signaling induces vast gene expression programs which necessitate the local formation of transcription factories at regulatory regions and large-scale alterations of the genome architecture to allow communication among distantly related cis-acting regions. This involves major stress at the genomic DNA level. Transcriptionally active regions are generally instable and prone to breakage due to the torsional stress and local depletion of nucleosomes that make DNA more accessible to damaging agents. A dedicated DNA damage response (DDR) is therefore essential to maintain genome integrity at these exposed regions. The DDR is a complex network involving DNA damage sensor proteins, such as the poly(ADP-ribose) polymerase 1 (PARP-1), the DNA-dependent protein kinase catalytic subunit (DNA-PKcs), the ataxia-telangiectasia-mutated (ATM) kinase and the ATM and Rad3-related (ATR) kinase, as central regulators. The tight interplay between the DDR and steroid hormone receptors has been unraveled recently. Several DNA repair factors interact with the androgen and estrogen receptors and support their transcriptional functions. Conversely, both receptors directly control the expression of agents involved in the DDR. Impaired DDR is also exploited by tumors to acquire advantageous mutations. Cancer cells often harbor germline or somatic alterations in DDR genes, and their association with disease outcome and treatment response led to intensive efforts towards identifying selective inhibitors targeting the major players in this process. The PARP-1 inhibitors are now approved for ovarian, breast, and prostate cancer with specific genomic alterations. Additional DDR-targeting agents are being evaluated in clinical studies either as single agents or in combination with treatments eliciting DNA damage (e.g., radiation therapy, including targeted radiotherapy, and chemotherapy) or addressing targets involved in maintenance of genome integrity. Recent preclinical and clinical findings made in addressing DNA repair dysfunction in hormone-dependent and -independent prostate and breast tumors are presented. Importantly, the combination of anti-hormonal therapy with DDR inhibition or with radiation has the potential to enhance efficacy but still needs further investigation.

Targeting CDK12 for Cancer Therapy: Function, Mechanism, and Drug Discovery

Cyclin-dependent kinase 12 (CDK12) is a member of the CDK family of proteins (CDK) and is critical for cancer development. Years of study into CDK12 have generated much information regarding the intricacy of its function and mechanism as well as inhibitors against it for oncological research. However, there remains a lack of understanding regarding the role of CDK12 in carcinogenesis and cancer prevention. An exhaustive comprehension of CDK12 will highly stimulate the development of new strategies for treating and preventing cancer. Here, we review the literature of CDK12, with a focus on its function, its role in signaling, and how to use it as a target for discovery of novel drugs for cancer prevention and therapy.

CDK12: A Potent Target and Biomarker for Human Cancer Therapy

Cyclin-dependent kinases (CDKs) are a group of serine/threonine protein kinases and play crucial roles in various cellular processes by regulating cell cycle and gene transcription. Cyclin-dependent kinase 12 (CDK12) is an important transcription-associated CDK. It shows versatile roles in regulating gene transcription, RNA splicing, translation, DNA damage response (DDR), cell cycle progression and cell proliferation. Recently, increasing evidence demonstrates the important role of CDK12 in various human cancers, illustrating it as both a biomarker of cancer and a potential target for cancer therapy. Here, we summarize the current knowledge of CDK12, and review the research advances of CDK12's biological functions, especially its role in human cancers and as a potential target and biomarker for cancer therapy.

Breast Cancer: A Molecularly Heterogenous Disease Needing Subtype-Specific Treatments

Breast cancer is the most commonly occurring cancer in women. There were over two-million new cases in world in 2018. It is the second leading cause of death from cancer in western countries. At the molecular level, breast cancer is a heterogeneous disease, which is characterized by high genomic instability evidenced by somatic gene mutations, copy number alterations, and chromosome structural rearrangements. The genomic instability is caused by defects in DNA damage repair, transcription, DNA replication, telomere maintenance and mitotic chromosome segregation. According to molecular features, breast cancers are subdivided in subtypes, according to activation of hormone receptors (estrogen receptor and progesterone receptor), of human epidermal growth factors receptor 2 (HER2), and or BRCA mutations. In-depth analyses of the molecular features of primary and metastatic breast cancer have shown the great heterogeneity of genetic alterations and their clonal evolution during disease development. These studies have contributed to identify a repertoire of numerous disease-causing genes that are altered through different mutational processes. While early-stage breast cancer is a curable disease in about 70% of patients, advanced breast cancer is largely incurable. However, molecular studies have contributed to develop new therapeutic approaches targeting HER2, CDK4/6, PI3K, or involving poly(ADP-ribose) polymerase inhibitors for BRCA mutation carriers and immunotherapy.

Comparison of BRCA versus non-BRCA germline mutations and associated somatic mutation profiles in patients with unselected breast cancer

The data on the phenotypes associated with some rare germline mutations in Chinese breast cancer patients are limited. The difference in somatic mutation profiles in breast cancer patients with germline BRCA and non-BRCA mutations remains unexplored. We interrogated the germline and somatic mutational profile of 524 Chinese breast cancer patients with various stages unselected for predisposing factors using a panel consisting of 520 cancer-related genes including 62 cancer susceptibility genes. We divided the patients into three groups according to germline mutations: Germline-BRCA1/2, Germline-others (non-BRCA) and Others (non-carriers). A total of 58 patients (11.1%) carried 76 likely pathogenic or pathogenic (LP/P) germline variants in 15 cancer predisposition genes. Germline BRCA1/2 mutations were detected from 29 (5.53%) patients; with 11 (2.10%) BRCA1 carriers and 18 (3.44%) BRCA2 carriers. In addition, LP/P germline mutations were detected in other genes including MUTYH (n=4), PALB2 (n=4), ATM (n=3), BRIP1 (n=3), CDH1 (n=3), RAD51C (n=3), CHEK2 (n=2), FANCA (n=2), PMS2 (n=2), TP53 (n=2), FANCI (n=1), FANCL (n=1) and PTEN (n=1). At least one variant of uncertain significance (VUS) was identified in 490 (93.5%) patients. Young age (P=0.011), premenopausal status (P=0.013), and breast/ovarian cancer family history (P=0.001) were correlated with germline mutations. Germline-BRCA1/2 group was detected with more missense (P=0.02) and less copy-number amplification (P=0.04) than Germline-others group. Meanwhile, Germline-others group and Others group are very similar (P>0.05). The mutation rates of AKT1, CCND1, FGFR1, and PIK3CA were different among the three groups. By investigating all breast and ovarian cancer-related genes listed in the US genetic guidelines, we identified 15 cancer susceptibility genes frequently mutated in the germline of our population and must be included in cancer predisposition screening. Our study contributed a better understanding of the tumor characteristics of patients with LP/P germline mutations.