Newly developed preclinical models reveal broad-spectrum CDK inhibitors as potent drugs for CRPC exhibiting primary resistance to enzalutamide.

Androgen-deprivation therapy is a standard treatment for advanced prostate cancer. However, most patients eventually acquire resistance and progress to castration-resistant prostate cancer (CRPC). In this study, we established new CRPC cell lines, AILNCaP14 and AILNCaP15, from LNCaP cells under androgen-deprived conditions. Unlike most pre-existing CRPC cell lines, both cell lines expressed higher levels of androgen receptor (AR) and prostate-specific antigen (PSA) than parental LNCaP cells. Moreover, these cells exhibited primary resistance to enzalutamide. Since AR signaling plays a significant role in the development of CRPC, PSA promoter sequences fused with GFP were introduced into AILNCaP14 cells to conduct GFP fluorescence-based chemical screening. We identified flavopiridol, a broad-spectrum CDK inhibitor, as a candidate drug that could repress AR transactivation of CRPC cells, presumably through the inhibition of phosphorylation of AR on the serine 81 residue (pARSer81 ). Importantly, this broad-spectrum CDK inhibitor inhibited the proliferation of AILNCaP14 cells both in vitro and in vivo. Moreover, a newly developed liver metastatic model using AILNCaP15 cells revealed that the compound attenuated tumor growth of CRPC harboring highly metastatic properties. Finally, we developed a patient-derived xenograft (PDX) model of CRPC and DCaP CR from a patient presenting therapeutic resistance to enzalutamide, abiraterone, and docetaxel. Flavopiridol successfully suppressed the tumor growth of CRPC in this PDX model. Since ARSer81 was found to be phosphorylated in clinical CRPC samples, our data suggested that broad-spectrum CDK inhibitors might be a potent candidate drug for the treatment of CRPC, including those exhibiting primary resistance to enzalutamide.

NFYA promotes malignant behavior of triple-negative breast cancer in mice through the regulation of lipid metabolism.

Two splicing variants exist in NFYA that exhibit high expression in many human tumour types. The balance in their expression correlates with prognosis in breast cancer, but functional differences remain unclear. Here, we demonstrate that NFYAv1, a long-form variant, upregulates the transcription of essential lipogenic enzymes ACACA and FASN to enhance the malignant behavior of triple-negative breast cancer (TNBC). Loss of the NFYAv1-lipogenesis axis strongly suppresses malignant behavior in vitro and in vivo, indicating that the NFYAv1-lipogenesis axis is essential for TNBC malignant behavior and that the axis might be a potential therapeutic target for TNBC. Furthermore, mice deficient in lipogenic enzymes, such as Acly, Acaca, and Fasn, exhibit embryonic lethality; however, Nfyav1-deficient mice exhibited no apparent developmental abnormalities. Our results indicate that the NFYAv1-lipogenesis axis has tumour-promoting effects and that NFYAv1 may be a safe therapeutic target for TNBC.

Role of Cancer Stem-like Cells in the Process of Invasion and Mesenchymal Transformation by a Reconstituted Triple-negative Breast Cancer Cell Population Resistant to p53-induced Apoptosis.

We investigated the role of cancer stem cells (CSCs) in a population of triple-negative breast cancer (TNBC) cells that are resistant to apoptosis. A human breast cancer cell population capable of inducing p53 expression with doxycycline (Dox) was created and used as an untreated control (UT). After the addition of Dox to UT for 5 days, the cell population reconstituted with cells showing resistance to apoptosis was named RE. Fluorescence-activated cell sorting (FACS) and immunostaining revealed that after the addition of Dox, the ratio of cells in the S and G2/M phases decreased in UT as apoptosis proceeded, but did not markedly change in apoptosis-resistant RE. CSC-like cells in RE exhibited a cell morphology with a larger ratio of the major/minor axis than UT. FACS showed that RE had a higher proportion of CSC-like cells and contained more CD44+CD24- mesenchymal CSCs than ALDH1A3+ epithelial-like CSCs. In a Matrigel invasion assay, UT was more likely to form a three-dimensional cell population, whereas RE exhibited a planar population, higher migration ability, and the up-regulated expression of epithelial-mesenchymal transition-related genes. These results provide insights into the mechanisms by which TNBC cells acquire treatment resistance at the time of recurrence.

HER2 G776S mutation promotes oncogenic potential in colorectal cancer cells when accompanied by loss of APC function.

Clinical cancer genome sequencing detects oncogenic variants that are potential targets for cancer treatment, but it also detects variants of unknown significance. These variants may interact with each other to influence tumor pathophysiology, however, such interactions have not been fully elucidated. Additionally, the effect of target therapy for those variants also unclarified. In this study, we investigated the biological functions of a HER2 mutation (G776S mutation) of unknown pathological significance, which was detected together with APC mutation by cancer genome sequencing of samples from a colorectal cancer (CRC) patient. Transfection of the HER2 G776S mutation alone slightly increased the kinase activity and phosphorylation of HER2 protein, but did not activate HER2 downstream signaling or alter the cell phenotype. On the other hand, the HER2 G776S mutation was shown to have strong oncogenic potential when loss of APC function was accompanied. We revealed that loss of APC function increased Wnt pathway activity but also increased RAS-GTP, which increased ERK phosphorylation triggered by HER2 G776S transfection. In addition, afatinib, a pan-HER tyrosine kinase inhibitor, suppressed tumor growth in xenografts derived from HER2 G776S-transfected CRC cells. These findings suggest that this HER2 mutation in CRC may be a potential therapeutic target.

Pattern of RECK CpG methylation as a potential marker for predicting breast cancer prognosis and drug-sensitivity.

The membrane-anchored glycoprotein RECK negatively regulates multiple metalloproteinases and is frequently downregulated in tumors. Forced RECK expression in cancer cells results in suppression of tumor angiogenesis, invasion, and metastasis in xenograft models. A previous methylome study on breast cancer tissues detected inverse correlation between RECK CpG methylation (in an intron-1 region) and relapse-free survival. In this study, we focused on another region of the RECK CpG island (a promoter/exon-1 region) and found an inverse correlation between its methylation and RECK-inducibility by an HDAC inhibitor, MS275, among a panel of breast cancer cell lines (n=15). In clinical samples (n=62), RECK intron-1 methylation was prevalent among luminal breast cancers as reported previously (26 of 38 cases; 68%) and particularly enriched in tumors of the ER+PR- subclass (10 of 10 cases) and of higher histological grades (Grade 2 and 3; 28 of 43 cases; P=0.006). In about a half of these cases, promoter/exon-1 methylation was absent, and hence, RECK may be inducible by certain drugs such as MS275. Our results indicate the value of combined use of two RECK methylation markers for predicting prognosis and drug-sensitivity of breast cancers.

Sal-like 4 (SALL4) suppresses CDH1 expression and maintains cell dispersion in basal-like breast cancer.

In cell cultures, the dispersed phenotype is indicative of the migratory ability. Here we characterized Sal-like 4 (SALL4) as a dispersion factor in basal-like breast cancer. Our shRNA-mediated SALL4 knockdown system and SALL4 overexpression system revealed that SALL4 suppresses the expression of adhesion gene CDH1, and positively regulates the CDH1 suppressor ZEB1. Cell behavior analyses showed that SALL4 suppresses intercellular adhesion and maintains cell motility after cell-cell interaction and cell division, which results in the dispersed phenotype. Our findings indicate that SALL4 functions to suppress CDH1 expression and to maintain cell dispersion in basal-like breast cancer.

[The case of a patient with peritoneal metastasis from cholangiocarcinoma who responded to adoptive immunotherapy and cetuximab].

A 59-year-old female patient underwent pancreaticoduodenectomy because of bile duct cancer 4 years before the first consultation at our clinic. Because the resected bile duct margin was positive, radiation therapy was administered to the hepatic hilum, 5-fluorouraci(l 5-FU) was continuously infused, and S-1 was administered as adjuvant therapy. Three years later, cancer of the uterine body was diagnosed. At the time of hysterectomy, nodules were observed in the Douglas pouch. Biopsy confirmed the presence of peritoneal metastasis from cholangiocarcinoma (hospital A). At the time of the first consultation, ascites was observed. Symptoms improved after the administration of bevacizumab( Bmab) and gemcitabine (GEM), but recurred after 7 months. The patient was admitted to hospital B because of impaired gastrointestinal passage and massive ascites. OK-432-combined adoptive immunotherapy, in which lymphocytes from the removed ascites were cultured and transferred into the abdominal cavity after OK-432 treatment, was performed. Examination of the specimen resected in hospital A indicated that it was strongly positive for epidermal growth factor receptor (EGFR), and hence, cetuximab( Cmab) was administered both at admission and after discharge. Cmab alone was continued and the tumor marker levels normalized. The patient is currently healthy at 7 years after the onset of peritoneal recurrence (5.5 years after the initiation of Cmab therapy).

Histone chaperone Spt6 is required for class switch recombination but not somatic hypermutation.

Activation-induced cytidine deaminase (AID) is shown to be essential and sufficient to induce two genetic alterations in the Ig loci: class switch recombination (CSR) and somatic hypermutation (SHM). However, it is still unknown how a single-molecule AID differentially regulates CSR and SHM. Here we identified Spt6 as an AID-interacting protein by yeast two-hybrid screening and immunoprecipitation followed by mass spectrometry. Knockdown of Spt6 resulted in severe reduction of CSR in both the endogenous Ig locus in B cells and an artificial substrate in fibroblast cells. Conversely, knockdown of Spt6 did not reduce but slightly enhanced SHM in an artificial substrate in B cells, indicating that Spt6 is required for AID to induce CSR but not SHM. These results suggest that Spt6 is involved in differential regulation of CSR and SHM by AID.

SPA-1 controls the invasion and metastasis of human prostate cancer.

Recent studies suggest that SIPA1 encoding a Rap GTPase-activating protein SPA-1 is a candidate metastasis efficiency-modifying gene in human breast cancer. In this study, we investigated the expression and function of SPA-1 in human prostate cancer (CaP). Immunohistochemical studies of tumor specimens from CaP patients revealed a positive correlation of SPA-1 expression with disease progression and metastasis. The correlation was recapitulated in human CaP cell lines; LNCaP that rarely showed metastasis in SCID mice expressed an undetectable level of SPA-1, whereas highly metastatic PC3 showed abundant SPA-1 expression. Moreover, SIPA1 transduction in LNCaP caused prominent abdominal lymph node metastasis without affecting primary tumor size, whereas shRNA-mediated SIPA1 knockdown or expression of a dominant-active Rap1 mutant (Rap1V12) in PC3 suppressed metastasis. LNCaP transduced with SPA-1 (LNCaP/SPA-1) showed attenuated adhesion to the precoated extracellular matrices (ECM) including collagens and fibronectin, due to defective ECM-medicated Rap1 activation. In addition, LNCaP/SPA-1 showed a diminished level of nuclear Brd4, which is known to bind SPA-1, resulting in reduced expression of a series of ECM-related genes. These results suggest that SPA-1 plays an important role in controlling metastasis efficiency of human CaP by regulating the expression of and interaction with ECM in the primary sites.

[A case of primary breast cancer who responded remarkably to the neoadjuvant chemotherapy with the combination of docetaxel and cyclophosphamide].

A 67-year-old woman visited our hospital with suspicion of right breast cancer. She underwent core needle biopsy, and her disease was diagnosed as breast cancer (invasive ductal carcinoma, ER- and PgR- positive, HER2-negative). We chose neoadjuvant chemotherapy, because the tumor size was over 3 cm in diameter and she wished to conserve her breast. She was elderly, and so without anthracycline base, we used a combination of docetaxel (75 mg/m(2)) and cyclophosphamide (600 mg/m(2)) q3w 6 cycles followed by breast-conserving therapy. During treatment, the patient remained very well and showed no major side effects except grade 4 neutropenia on an outpatient basis. After 6 cycles, ultrasonography and mammography indicated the residual tumor, but breast MRI did not detect any tumor. Pathological examination showed absence of invasive tumor or only focal residual tumor cells (QpCR). We concluded that the combination of docetaxel and cyclophosphamide was a good option for neoadjuvant chemotherapy for early breast cancer.

Prevalence and incidence of anemia in Japanese cancer patients receiving outpatient chemotherapy.

Anemia in cancer patients has been under-recognized and little studied in Japan. To gain some insight into cancer-related anemia in Japanese patients undergoing outpatient chemotherapy, we performed a single-center retrospective study of the prevalence and incidence of anemia in 148 patients with solid tumors treated at the Kyoto University Hospital Outpatient Oncology Unit. We classified the cases of anemia in accordance with the National Cancer Institute Common Terminology Criteria for Adverse Events (version 3.0). Of 148 patients, 65 (44%) were anemic at the start of chemotherapy, 19 (13%) of whom had anemia of grade 2 or higher. Chemotherapy further increased the number of anemic patients, with 125 (84%) being anemic at some point during chemotherapy, and 61 (41%) of these having anemia of grade 2 or higher. Among the 83 patients without anemia at the start of chemotherapy, 60 (72%) developed anemia during chemotherapy, 15 (18%) of whom had anemia of grade 2 or higher. This is the first report showing a high prevalence and incidence of anemia in Japanese patients undergoing outpatient chemotherapy. Better recognition and management of cancer-related anemia are required in Japan. To this end, randomized controlled trials evaluating the effects of erythropoietic agents on patients' survival and quality of life are necessary.

[Evaluation of therapeutic regimens for taxane-resistant recurrent/metastatic breast cancer].

Taxanes (TX) were administered to 246 of 292 patients with recurrent/metastatic breast cancer (MBC) who were treated in Hiei Hospital between January 2001 and May 2006. Recently, TX has been increasingly prescribed for preoperative treatment and postoperative adjuvant therapy. To improve the prognosis of MBC, regimens effective for TX-resistant cancer patients should be developed. In this study, with respect to hormone receptor (HR) and Her 2/neu (HER 2), we retrospectively investigated whether our series responded to the regimens used after TX resistance was acquired. As post TX-resistance therapy (trastuzumab was combined in HER2-positive patients), 387 treatment regimens were administered to 166 patients. The following regimens achieved a response rate (patients achieving PR or CR/patients who could be evaluated) of 10% or more: combination therapy with TX and capecitabine (11/61, 18%), CPT-11 (10/57, 17.5%), vinorelbine (5/46, 10.9%), MFL-P (continuous treatment with MTX, 5-FU, LV, and CDDP) (12/47, 25.5%), and DMpC (5'-DFUR, MPA, CPA p.o.) (5/16, 31.2%). The latter 2 regimens achieved a high response rate,and some HR (-) and HER 2 (-) patients also responded to these regimens. In HR (+) or HER 2 (+) patients who responded to TX, survival was longer than that of non-responders. However, there was no difference in the treatment responsiveness of post-TX regimens between TX-responders and non-responders, suggesting the survival-prolonging effect of TX.

Retrospective analysis of 27 consecutive patients treated with docetaxel/nedaplatin combination therapy as a second-line regimen for advanced esophageal cancer.

BACKGROUND: The aim of this study was to evaluate the efficacy and safety of combination therapy with docetaxel and nedaplatin in advanced esophageal cancer as a second-line regimen in an outpatient setting. METHODS: Twenty-seven consecutive patients with advanced esophageal cancer who received docetaxel/nedaplatin combination therapy as a second-line regimen were retrospectively evaluated. The combination therapy consisted of intravenous administration of docetaxel 30 mg/m(2) and nedaplatin 40 mg/m(2) every 2 weeks. RESULTS: The patients received a median of 7.4 cycles of treatment (range, 2-25 cycles ). No complete response was observed, and 3 of the 27 patients (11%) achieved partial responses. The disease control rate (partial response + stable disease) was 52%. The median survival time (MST) was 11.4 months. Severe hematological adverse events (grade 3-4) were: neutropenia (n = 10; 37%) and anemia (n = 5; 19%); there was neither febrile neutropenia nor grade 3-4 thrombocytopenia. Furthermore, no severe nonhematological adverse events or treatment-related deaths were observed. CONCLUSION: Combination therapy of docetaxel with nedaplatin was safe and well tolerated; however, the development of more effective therapy is warranted to improve the prognosis of esophageal cancer.

Single-agent gemcitabine for biliary tract cancers. Study outcomes and systematic review of the literature.

OBJECTIVE: The aim of this study was to investigate the outcomes of gemcitabine-treated patients with inoperable biliary tract cancers. METHODS: We conducted a retrospective study of consecutively treated 22 inoperable biliary tract cancer patients with gemcitabine (500-1,000 mg/m(2) on days 1, 8, 15 every 4 weeks) as first-line, and 17 patients as second- or third-line treatment. RESULTS: The response rate of patients treated with gemcitabine as first-line and second- or third-line treatment was 5.3 and 28.5%, respectively. The median overall survival time in the first-, and second- or third-line treatment groups was 8.3 and 17.0 months, and the 1-year survival rate was 44.0 and 50.9%, respectively. The present study also suggests the possibility that the prognosis of patients with high levels of C-reactive protein and total bilirubin, or a low level of albumin might be worse. CONCLUSIONS: Our results indicate that the treatment of inoperable biliary tract cancers with gemcitabine is feasible. There was no difference in the response rate and overall survival between biliary tract cancer patients in the first- and second- or third-line treatment groups. We also present the systematic review of literature of the recent treatment results of biliary tract cancers treated with gemcitabine.

RNA-editing cytidine deaminase Apobec-1 is unable to induce somatic hypermutation in mammalian cells.

Antibody diversification by somatic hypermutation, gene conversion, and class switch recombination is completely dependent on activation-induced cytidine deaminase (AID). A recent report showing induction of DNA mutations in Escherichia coli by overexpression of AID, Apobec-1, and related members of the RNA-editing cytidine deaminase family suggested that they may directly modify deoxycytidine in DNA in mammalian cells (DNA-editing model). We therefore examined whether Apobec-1 bona fide RNA-editing enzyme could show somatic hypermutation and class switching activities in murine B lymphocytes and fibroblasts. Unlike AID, Apobec-1 was unable to induce somatic hypermutation or class switching. The results force a reevaluation of the physiological significance of the DNA deaminase activities of AID and Apobec-1 in E. coli and in vitro.

Activation-induced cytidine deaminase links class switch recombination and somatic hypermutation.

Activation-induced cytidine deaminase (AID), a putative RNA-editing cytidine deaiminase that is expressed strictly in activated B cells, is indispensable in three apparently distinct genetic alterations of immunoglobulin genes-namely, class switch recombination, somatic hypermutation, and gene conversion. Recent findings led us to propose a common DNA cleaving mechanism, in which the transient secondary structure of the S and V region DNA is recognized by a nicking enzyme regulated by the putative RNA-editing activity of AID.

AID enzyme-induced hypermutation in an actively transcribed gene in fibroblasts.

Activation-induced cytidine deaminase (AID), a putative RNA-editing enzyme, is indispensable for somatic hypermutation (SHM), class switch recombination, and gene conversion of immunoglobulin genes, which indicates a common molecular mechanism for these phenomena. Here we show that ectopic expression of AID alone can induce hypermutation in an artificial GFP substrate in NIH 3T3 murine fibroblast cells. The frequency of mutations was closely correlated with the level of transcription of the target gene, and the distribution of mutations in NIH 3T3 cells was similar to those of SHM in B lymphocytes. These results indicate that AID is sufficient for the generation of SHM in an actively transcribed gene in fibroblasts, as well as B cells, and that any of the required cofactors must be present in these fibroblasts.

The AID enzyme induces class switch recombination in fibroblasts.

The switch of the immunoglobulin isotype from IgM to IgG, IgE or IgA is mediated by class switch recombination (CSR). CSR changes the immunoglobulin heavy chain constant region (CH) gene from Cmu to one of the other CH genes. Somatic hypermutation introduces massive numbers of point mutations in the immunoglobulin variable (V) region gene, giving rise to immunoglobulin with higher affinity. Activation-induced cytidine deaminase (AID), a putative RNA-editing cytidine deaminase, is expressed strictly in activated B cells and is indispensable in both CSR and somatic hypermutation. But the exact function of AID is unknown. Here we show that ectopic expression of AID induces CSR in an artificial switch construct in fibroblasts at a level comparable to that in stimulated B cells. Sequences around recombination junctions in the artificial substrate have features similar to endogenous CSR junctions. Furthermore, AID-induced CSR in fibroblasts is dependent on transcription of the target S region, as shown in endogenous CSR in B cells. The results show that AID is the only B-cell-specific factor required for initiation of the CSR reaction in the activated locus.