c-MET-positive circulating tumor cells and cell-free DNA as independent prognostic factors in hormone receptor-positive/HER2-negative metastatic breast cancer.

BACKGROUND: Endocrine therapy resistance in hormone receptor-positive/HER2-negative (HR+/HER2-) breast cancer (BC) is a significant clinical challenge that poses several unmet needs in the management of the disease. This study aimed to investigate the prognostic value of c-MET-positive circulating tumor cells (cMET+ CTCs), ESR1/PIK3CA mutations, and cell-free DNA (cfDNA) concentrations in patients with hormone receptor-positive (HR+) metastatic breast cancer (mBC). METHODS: Ninety-seven patients with HR+ mBC were prospectively enrolled during standard treatment at Samsung Medical Center. CTCs were isolated from blood using GenoCTC® and EpCAM or c-MET CTC isolation kits. PIK3CA and ESR1 hotspot mutations were analyzed using droplet digital PCR. CfDNA concentrations were calculated using internal control copies from the ESR1 mutation test. Immunocytochemistry was performed to compare c-MET overexpression between primary and metastatic sites. RESULTS: The proportion of c-MET overexpression was significantly higher in metastatic sites than in primary sites (p = 0.00002). Survival analysis showed that c-MET+ CTC, cfDNA concentration, and ESR1 mutations were significantly associated with poor prognosis (p = 0.0026, 0.0021, and 0.0064, respectively) in HR+/HER2- mBC. By contrast, EpCAM-positive CTC (EpCAM+ CTC) and PIK3CA mutations were not associated with progression-free survival (PFS) in HR+/HER2- mBC. Multivariate analyses revealed that c-MET+ CTCs and cfDNA concentration were independent predictors of PFS in HR+/HER2- mBC. CONCLUSIONS: Monitoring c-MET+ CTC, rather than assessing c-MET expression in the primary BC site, could provide valuable information for predicting disease progression, as c-MET expression can change during treatment. The c-MET+ CTC count and cfDNA concentration could provide complementary information on disease progression in HR+ /HER2- mBC, highlighting the importance of integrated liquid biopsy.

No evidence of delay in colorectal cancer diagnosis during the COVID-19 pandemic in Gwangju and Jeonnam, Korea

Objectives: We evaluated whether the coronavirus disease 2019 (COVID-19) pandemic caused delays in the diagnosis and treatment of colorectal cancer (CRC) in Korea, where there have been no regional or hospital lockdowns during the pandemic period. Methods: Data on CRC patients (n=1,445) diagnosed in Gwangju Metropolitan City and Jeonnam Province between January 2019 and December 2021 were assessed. The stage at the time of CRC diagnosis, route to diagnosis, time to initial cancer treatment, and length of hospital admission were compared before and during the COVID-19 pandemic. Logistic regression was also performed to identify factors associated with the risk for diagnosis in an advanced stage. Results: No negative effects indicating a higher CRC stage at diagnosis or delayed treatment during the pandemic were observed. Instead, the risk for an advanced stage at diagnosis (TNM stage III/IV) decreased in CRC patients diagnosed during the pandemic (odds ratio, 0.768; 95% confidence interval, 0.647 to 0.911). No significant differences in the interval from diagnosis to operation or chemotherapy were observed. Conclusion: No negative effects on CRC diagnosis and treatment were found until the end of 2021, which may be related to the small magnitude of the COVID-19 epidemic, the absence of a lockdown policy in Korea, and the rebound in the number of diagnostic colonoscopy procedures in 2021.

Difference of stage at cancer diagnosis by socioeconomic status for four target cancers of the National Cancer Screening Program in Korea: Results from the Gwangju and Jeonnam cancer registries.

BACKGROUND: The aim of this study was to evaluate whether stage at cancer diagnosis differed according to patient economic status. METHODS: A total of 10,528 patients with cancer of the stomach, colorectum, breast, or cervix, which are target organs of the Korean National Cancer Screening Program (NCSP; fully implemented in 2005) were extracted from population-based cancer registries. The patients were classified into four groups based on socioeconomic status (SES), as determined using their National Health Insurance (NHI) monthly premium at the time of cancer diagnosis. Cancer stage at diagnosis was defined as early (in situ/local) or late stage (regional/distant) based on the Surveillance, Epidemiology, and End Results (SEER) summary stage. Multivariable logistic regression analysis was performed to estimate the risk of non-local stage using age, residential area, and community deprivation index as covariates. RESULTS: The lowest SES subjects showed significantly higher risks of being diagnosed at a later stage for stomach, colorectal, and female breast cancer, but not for cervical cancer, compared with the highest SES subjects. The estimated ORs were 1.28 (95% CI, 1.10-1.49), 1.29 (95% CI, 1.03-1.61), and 1.35 (95% CI, 1.02-1.81) in the lowest SES subjects with stomach, colorectal, and breast cancer, respectively. CONCLUSIONS: In conclusion, later stage diagnoses of stomach, colon, and female breast cancer are still associated with SES in Korea in the era of the NCSP for the lower SES population.

Genetic and expressional alterations of CHD genes in gastric and colorectal cancers.

AIMS: Chromodomain helicase DNA-binding protein (CHD) is a regulator of the chromatin remodelling process. The aim was to determine the CHD1, CHD2, CHD3, CHD4, CHD7, CHD8 and CHD9 mutational status of mononucleotide repeats in gastric and colorectal cancers with microsatellite instability (MSI). METHODS AND RESULTS: The repeats were determined in 28 gastric cancers (GCs) with high MSI (MSI-H), 45 GCs with low MSI (MSI-L)/stable MSI (MSS), 35 colorectal cancers (CRCs) with MSI-H and 45 CRCs with MSI-L/MSS by single-strand conformation polymorphism analysis. CHD4 and CHD8 expression was also examined in GCs and CRCs by immunohistochemistry. CHD1, CHD2, CHD3, CHD4, CHD7, CHD8 and CHD9 mutations were found in five, 19, three, five, seven, 10 and seven cancers, respectively. They were detected in MSI-H cancers, but not in MSI-L/MSS cancers. Loss of CHD4 expression was observed in 56.4% of the GCs and 55.7% of the CRCs, and loss of CHD8 was observed in 35.7% of the GCs and 28.6% of the CRCs. The cancers with CHD4 and CHD8 mutations showed loss of CHD4 and CHD8 expression, respectively. CONCLUSIONS: Frameshift mutation and loss of expression of CHD genes are common in GCs and CRCs with MSI-H.These alterations might contribute to cancer pathogenesis by deregulating CHD-mediated chromatin remodelling.

Mutational analysis of mononucleotide repeats in dual specificity tyrosine phosphatase genes in gastric and colon carcinomas with microsatellite instability.

Coordinated protein phosphorylation and dephosphorylation are crucial in the regulation of cell signaling, and disruption of the coordination is known to play important roles in cancer development. Recent reports revealed that classical protein tyrosine phosphatase (PTP)-encoded genes are somatically mutated in human colorectal cancer. However, data on dual specificity phosphatase (DPTP) gene mutations in human cancers are lacking. By analyzing a public genomic database, we found that five DPTP genes, CDC14A, MTM1, MTMR3, SSH1, and SSH2, have mononucleotide repeats in their coding DNA sequences. To see whether these genes are mutated in cancers with microsatellite instability (MSI), we analyzed the mononucleotide repeats in 26 gastric cancers (GC) with MSI (MSI-H), 12 GC with low MSI (MSI-L), 45 GC with stable MSI (MSS), 33 colorectal cancers (CRC) with MSI-H, 14 CRC with MSI-L, and 45 CRC with MSS by single-strand conformation polymorphism (SSCP). We found CDC14A and MTMR3 mutations in five and one cancer (s), respectively. These mutations were detected in MSI-H cancers, but not in MSI-L or MSS cancers. The GC and CRC with MSI-H harbored the mutations in 15% and 6%, respectively. The CDC14A and MTMR3 mutations detected in the GC and CRC were deletion or duplication mutations of one base in the nucleotide repeats that would result in premature stops of the amino acid syntheses. Our data show that frameshift mutations of DPTP genes in MSI-H cancers occur at moderate frequencies. The data suggested that alterations in the CDC14A and MTMR3 genes may play a role in the development of GC and CRC with MSI-H by deregulating phosphatase functions possibly together with mutations of classical PTP genes.

Oncogenic NRF2 mutations in squamous cell carcinomas of oesophagus and skin.

Nuclear factor erythroid-related factor 2 (NRF2) encodes a transcription factor that induces expression of cytoprotective proteins upon oxidative stress and oncogenic NRF2 mutations have been found in lung and head/neck cancers that inactivate KEAP1-mediated degradation of NRF2. The aim of this study was to catalogue NRF2 mutations in other human cancers. For this, we analysed 1145 cancer tissues from carcinomas from oesophagus, skin, uterine cervix, lung, larynx, breast, colon, stomach, liver, prostate, urinary bladder, ovary, uterine cervix, and kidney, and meningiomas, multiple myelomas, and acute leukaemias by single-strand conformation polymorphism (SSCP) assay. We detected NRF2 mutations in oesophagus (8/70; 11.4%), skin (1/17; 6.3%), lung (10/125; 8.0%), and larynx (3/23; 13.0%) cancers. Of note, all of the 22 mutations except one were found in squamous cell carcinomas (SCCs) (95.5%). The mutations were observed within or near DLG and ETGE motifs that are important in NRF2 and KEAP1 interaction. All of the oesophageal SCCs and skin SCCs with the NRF2 mutations showed increased NRF2 expression in the nuclei. However, none of the SCCs from oesophagus and skin harboured KEAP1 mutation. Our study demonstrated here that NRF2 mutation occurs not only in lung and head/neck cancers, but also in oesophageal and skin cancers. Our data suggest that the NRF2 mutation plays a role in the development of SCC and is a feature of SCC.

Expression of CARD6, an NF-kappaB activator, in gastric, colorectal and oesophageal cancers.

AIMS: Activation of nuclear factor-kappa B (NF-kappaB) signalling is considered a crucial mechanism in the development of cancers. Caspase-associated recruitment domain 6 (CARD6) is a protein that activates NF-kappaB signalling evoked by RIP1, RIP2, Bcl-10 and MEKK. In this study, we analysed tissue expression of CARD6 protein in oesophageal squamous cell carcinoma (ESCC), gastric adenocarcinomas (GC) and colorectal adenocarcinomas (CRC). METHODS: We analysed the expression of CARD6 protein in 58 ESCC, 100 GC and 103 CRC patients' tissues by immunohistochemistry using a tissue microarray (TMA) approach. RESULTS: We found CARD6 immunostaining in cancer cells of ESCC (41/58; 70.7%), GC (45/100; 45.0%) and CRC (81/103; 78.6%). In the GC, intestinal-type GC (77.8%) showed higher expression of CARD6 than diffuse-type GC (20.0%) and mixed-type GC (50.0%). By contrast, corresponding normal epithelial cells of oesophagus (0%), stomach (8.0%) and colon (5.0%) displayed lower frequencies of CARD6 immunostaining. The CARD6 immunostaining was observed in nucleus/cytoplasm (ESCC) or cytoplasm (GC and CRC). The CARD6 expression was evident from an early TNM stage (stage I). CONCLUSION: The increased expression of CARD6 in ESCC, GC and CRC tissues compared to their corresponding normal cells suggested that neoexpression of CARD6 might be related to activation of NF-kappaB pathway in the cancers and might play a role in the development of most types of gastrointestinal cancers.

Novel somatic frameshift mutations of genes related to cell cycle and DNA damage response in gastric and colorectal cancers with microsatellite instability.

AIMS AND BACKGROUND: Microsatellite instability (MSI) in sporadic gastric cancer (GC) and colorectal cancer (CRC) causes frameshift mutations in gene sequences that contribute to cancer pathogenesis. Many mutations have already been identified in these two cancer types, but some are still undiscovered. METHODS: We analyzed seven genes (cell cycle control and DNA damage signaling/repair-related genes) with seven or more mononucleotide repeats in 30 GC samples with high MSI (MSI-H), 15 GC samples with low MSI (MSI-L), 45 GC samples that were microsatellite stable (MSS), 33 CRC samples with MSI-H, 15 CRC samples with MSI-L, and 45 CRC samples that were MSS. Single-strand conformation polymorphism (SSCP) and DNA sequencing were used for the analysis. RESULTS: We found somatic frameshit mutations of the KNTC1 (6.7% GC, 12.1% CRC), ZC3H13 (3.3% GC, 15.2% CRC), CENPH (6.7% GC), TOPBP1 (3.0% CRC), NDCO80 (3.0% CRC), RIF1 (6.7% GC), and NBS1 (3.3% GC, 3.0% CRC) genes in the cancers with MSI-H. Mutations were detected in MSI-H, but not in MSI-L or MSS samples. CONCLUSIONS: Novel frameshift mutations occurred in seven genes in GC and CRC with MSI-H. The results of our study suggest that the mutations might contribute to the development of GC and CRC with MSI by deregulation of the cell cycle and DNA damage signaling/repair.

NF-kappaB signalling proteins p50/p105, p52/p100, RelA, and IKKepsilon are over-expressed in oesophageal squamous cell carcinomas.

AIMS: Nuclear factor-kappa B (NF-kappaB) activation has been recognised as an important mechanism in the development of cancers. However, expression status of NF-kappaB-related proteins in oesophageal squamous cell carcinoma (ESCC) tissues is largely unknown. In this study, we analysed expressions of NF-kappaB members (p50/105, p52/p100 and RelA) and IKKepsilon in ESCC tissues. METHODS: We analysed the expression of p50/105, p52/p100, RelA and IKKepsilon in 58 ESCC patients' tissues by immunohistochemistry using a tissue microarray (TMA) method. RESULTS: Normal oesophageal squamous cells expressed p50/105, p52/p100 and RelA in 5%, 79% and 10% of the tissues in cytoplasm, respectively; however, only p52/p100 was expressed in the nuclei (12%). The cancer tissues expressed p50/105, p52/p100 and RelA in 93%, 95% and 95% in cytoplasm and/or nuclei, respectively. Nuclear immunostainings of NF-kappaB members p50/105, p52/p100 and RelA, which are considered activation of NF-kappaB signalling, were observed in 34%, 60% and 26% of the cancers, respectively. IKKepsilon is expressed in cytoplasm in 50% of the normal squamous tissues and 84% of the cancer tissues. However, none of the expression of p50/105, p52/p100, RelA or IKKepsilon was associated with pathological characteristics, including differentiation, depth of invasion and TNM stage. CONCLUSION: The increased nuclear expressions of p50/105, p52/p100 and RelA as well as increased cytoplasmic expression of IKKepsilon in the ESCC tissues compared to the normal squamous cells suggested that over-expression of these proteins may be related to activation of the NF-kappaB pathway and might play a role in the development of ESCC.

Immunohistochemical analysis of NF-kappaB signaling proteins IKKepsilon, p50/p105, p52/p100 and RelA in prostate cancers.

Activation of nuclear factor-kappa B (NF-kappaB) signaling is considered an important mechanism in the development of prostate cancers. A recent study revealed that IkappaB kinase epsilon (IKKepsilon), an activator of NF-kappaB, was overexpressed in breast cancers and acted as an oncogene. Expression of NF-kappaB members has been reported in prostate cancer tissues, but expression of IKKepsilon has not yet been studied in prostate cancers. In this study, we attempted to explore as to whether expressions of IKKepsilon and NF-kappaB members p50/105, p52/p100 and RelA are altered in prostate cancers. We analyzed the expression of IKKepsilon, p50/105, p52/p100 and RelA in 107 prostate adenocarcinoma tissues by immunohistochemistry using a tissue microarray (TMA) method. In the TMA, IKKepsilon is expressed in basal cells, but not in alveolar cells in normal prostate glands. IKKepsilon is expressed in 60.0% of prostate intraepithelial neoplasm (PIN) and 70.1% of the prostate cancers in the cytoplasm. Nuclear immunostainings of NF-kappaB members p50/105, p52/p100 and RelA, which are considered activation of NF-kappaB signaling, were observed respectively in 28.0%, 18.7% and 37.4% of the cancers. Nuclear staining was detected neither in normal alveolar cells nor in PIN. However, none of the expression of p50/105 nor p52/p100 nor RelA nor IKKepsilon was associated with pathologic characteristics, including size of the cancers, age, Gleason score and stage. The increased cytoplasmic expression of IKKepsilon as well as the increased nuclear expressions of p50/105, p52/p100 and RelA in the prostate cancers compared to normal alveolar cells suggested that overexpression of these proteins may be related to activation of the NF-kappaB pathway and might play a role in tumorigenesis of prostate cancers.

Mutational analysis of IDH1 codon 132 in glioblastomas and other common cancers.

Missense somatic mutations in IDH1 gene affecting codon 132 have recently been reported in glioblastoma multiforme (GBM) and other gliomas. The recurrent nature of the IDH1 mutations in the same amino acid strongly suggests that the mutations may play important roles in the pathogenesis of glial tumors. The aim of this study was to see whether the IDH1 codon 132 mutations occur in other human cancers besides glial tumors. We also attempted to confirm the occurrence of the IDH1 mutations in GBM of Korean patients. We have analyzed 1,186 cancer tissues from various origins, including carcinomas from breast, colon, lung, stomach, esophagus, liver, prostate, urinary bladder, ovary, uterine cervix, skin and kidney, and malignant mesotheliomas, primary GBM, malignant meningiomas, multiple myelomas and acute leukemias by single-strand conformation polymorphism analysis. We found four IDH1 codon 132 mutations in the GBM (4/25; 16.0%), two in the prostate carcinomas (2/75; 2.7%) and one in the B-acute lymphoblastic leukemias (B-ALL) (1/60; 1.7%), but none in other cancers. The IDH1 mutations consisted of five p.R132H and two p.R132C mutations. The data indicate that IDH1 codon 132 mutations occur not only in GBM, but also in prostate cancers and B-ALL. This study suggests that despite the infrequent incidence of the IDH1 mutations in prostate cancers and B-ALL, mutated IDH1 could be therapeutically targeted in these cancers and in glial tumors with the IDH1 mutations.

Frameshift mutations of autophagy-related genes ATG2B, ATG5, ATG9B and ATG12 in gastric and colorectal cancers with microsatellite instability.

Mounting evidence indicates that alterations of autophagy processes are directly involved in the development of many human diseases, including cancers. Autophagy-related gene (ATG) products are main players in the autophagy process. In humans there are 16 known ATG genes, of which four (ATG2B, ATG5, ATG9B and ATG12) have mononucleotide repeats with seven or more nucleotides. Frameshift mutations of genes with mononucleotide repeats are features of cancers with microsatellite instability (MSI). It is not known whether ATG genes with mononucleotide repeats are altered by frameshift mutations in gastric and colorectal carcinomas with MSI. For this, we analysed the mononecleotide repeats in ATG2B, ATG5, ATG9B and ATG12 in 32 gastric carcinomas with high MSI (MSI-H), 13 gastric carcinomas with low MSI (MSI-L), 43 colorectal carcinomas with MSI-H and 15 colorectal carcinomas with MSI-L by a single-strand conformation polymorphism (SSCP) analysis. We found ATG2B, ATG5, ATG9B and ATG12 mutations in 10, 2, 13 and 0 cancers, respectively. The mutations were detected in MSI-H cancers but not in MSI-L cancers. Gastric and colorectal cancers with MSI-H harboured one or more ATG mutations in 28.1% and 27.9%, respectively. Our data indicate that frameshift mutations in ATG genes with mononucleotide repeats are common in gastric and colorectal carcinomas with MSI-H, and suggest that these mutations may contribute to cancer development by deregulating the autophagy process.

Regulation of telomeric repeat binding factor 1 binding to telomeres by casein kinase 2-mediated phosphorylation.

Telomere maintenance is essential for continued cell proliferation and chromosome stability. Telomeres are maintained by telomerase and a collection of associated proteins. The telomeric protein telomeric repeat binding factor 1 (TRF1) negatively regulates telomere length by inhibiting access of telomerase at telomere termini. Here we report that TRF1 interacts with the beta subunit of casein kinase 2 (CK2) and serves as a substrate for CK2. CK2-mediated phosphorylation is required for the efficient telomere binding of TRF1 in vitro and in vivo. Inhibition of CK2 by the CK2 inhibitor 5,6-dichloro-1-beta-d-ribofuranosylbenzimidazole decreased the ability of TRF1 to bind telomeric DNA. The resulting telomere-unbound form of TRF1 was then ubiquitinated and degraded by the proteasome. Partial knockdown of CK2 by small interfering RNA resulted in removal of TRF1 from telomeres and subsequent degradation of TRF1. Mapping of the CK2 target site identified threonine 122 as a substrate in TRF1. A threonine to alanine change at this position led to a diminished DNA binding due to reduced dimerization of TRF1. In addition, phosphorylation of threonine 122 seemed critical for TRF1-mediated telomere length control. Our findings suggest that CK2-mediated phosphorylation of TRF1 plays an important role in modulating telomere length homeostasis by determining the levels of TRF1 at telomeres.

Telomeric DNA damage by topoisomerase I. A possible mechanism for cell killing by camptothecin.

Topoisomerase I adjusts torsional stress in the genome by breaking and resealing one strand of the helix through a transient covalent coupling between enzyme and DNA. Camptothecin, a specific topoisomerase I poison, traps this covalent intermediate, thereby damaging the genome. Here we examined the activity of topoisomerase I at telomeric repeats to determine whether telomere structures are targets for DNA damage. We show that topoisomerase I is catalytically active in cleaving the G-rich telomeric strand in vitro in the presence of camptothecin but not in cleaving the C-rich strand. The topoisomerase I cleavage site is 5'-TT (downward arrow) AGGG-3' (cleavage site marked by the downward arrow). We also show that endogenous topoisomerase I can access telomeric DNA in vivo and form camptothecin-dependent covalent complexes. Therefore, each telomeric repeat represents a potential topoisomerase I cleavage site in vivo. Because telomere structures are comprised of a large number of repeats, telomeres in fact represent a high concentration of nested topoisomerase I sites. Therefore, more telomeric DNA damage by camptothecin could occur in cells with longer telomeres when cells possess equivalent levels of topoisomerase I. The evidence presented here suggests that DNA damage at telomeric repeats by topoisomerase I is a prominent feature of cell killing by camptothecin and triggers camptothecin-induced apoptosis.

Down-regulation of DNA topoisomerase IIalpha in human colorectal carcinoma cells resistant to a protoberberine alkaloid, berberrubine.

Berberrubine, a protoberberine alkaloid that exhibits antitumor activity in animal models, has been identified as a specific poison of DNA topoisomerase II in vitro. To better understand the mechanisms of cellular response to berberrubine, human colorectal carcinoma cells (AMC5) were selected for resistance to berberrubine. The resulting cell line (AMC5/B1) was 5.3-fold resistant to berberrubine in the absence of MDR1 overexpression. The AMC5/B1 line was cross-resistant to topoisomerase II-targeted drugs but showed no cross-resistance to other antitumor drugs. The patterns of cross-resistance to various drugs led us to examine the cellular contents of topoisomerase II. Topoisomerase II activity was approximately 2.8-fold lower in AMC5/B1 cells compared with parental cells. The AMC5/B1 line contained approximately 5-fold decrease in topoisomerase IIalpha protein level and approximately 2.5-fold decrease in topoisomerase IIalpha mRNA level. A comparison of the degradation kinetics of topoisomerase IIalpha mRNA demonstrated that there was no difference in mRNA stability between the two cell lines. Furthermore, the activity of topoisomerase IIalpha promoter in AMC5/B1 cells was about 25% of that in AMC5 parental cells when transient transfection experiments were performed with the promoter-luciferase reporter gene. These results indicate that down-regulation of topoisomerase IIalpha in AMC5/B1 cells occurs at the transcriptional level. Nucleotide sequencing of the topoisomerase IIalpha promoter regions revealed no mutations in AMC5/B1 cells. In summary, resistance to berberrubine in AMC5 cells is associated with decreased level of catalytically active topoisomerase IIalpha, suggesting that topoisomerase IIalpha is the cellular target of berberrubine in vivo.