CKS1B nuclear expression is inversely correlated with p27Kip1 expression and is predictive of an adverse survival in patients with multiple myeloma

Identification of CKS1B as a prognostic indicator and a predictive marker for immunotherapy in pancreatic cancer

As a regulatory subunit of cyclin kinase, CKS1B promotes cancer development and is associated with poor prognosis in multiple cancer patients. However, the intrinsic role of CKS1B in pancreatic cancer remains elusive. In our research, CKS1B expression in pancreatic tumor tissue was higher than that in normal tissue by TCGA, Oncomine and CPTAC databases analysis. Similar result was verified in our center tissues by qRT-PCR. CKS1B expression was closely relevant to histologic grading, prognosis, and TMB. GSEA showed that CKS1B mainly participated in the regulation of autophagy and T cell receptor signaling pathway. Furthermore, CIBERSORT analysis showed that there was a strong correlation between CKS1B expression and tumor immune cells infiltration. Drug sensitivity analysis showed that patients with high CKS1B expression appeared to be more sensitive to gemcitabine, 5-fluorouracil, and paclitaxel. We then investigated cell viability and migratory ability by CCK8 and transwell assay, respectively. Results indicated that CKS1B knockdown by short hairpin RNA significantly reduced pancreatic cancer cell viability and invasion via regulating PD-L1 expression. In conclusion, our research further demonstrates the role of CKS1B in pancreatic cancer and the signaling pathways involved. The association of CKS1B with immune infiltration and immune checkpoint may provide a new direction for immunotherapy of pancreatic cancer.

Increased Expression of SETDB1 Predicts Poor Prognosis in Multiple Myeloma

Several genes on chromosome 1q21 region predict a high risk of multiple myeloma (MM); however, the underlying molecular pathology remains elusive. Overexpression, amplification, or activation of SET Domain Bifurcated 1 (SETDB1), which is located on 1q21, is closely associated with poor prognosis of many human solid malignancies. In our study, upregulation of SETDB1 might indicate an unfavorable prognosis of MM using bioinformatics analysis from GEO databases and MMRF-CoMMpass. Here, increased SETDB1 expression was observed in the plasma cells from newly diagnosed multiple myeloma patients compared to those from the normal controls. Meanwhile, SETDB1 overexpression was the result of increased copy numbers of SETDB1 gene. In MM patients, the Kaplan-Meier analysis was employed to demonstrate that increased SETDB1 expression was associated with shorter overall survival (OS) and event-free survival (EFS). Besides, we conducted multifactorial cox regression analysis to state that SETDB1 expression was an independent biomarker for OS and EFS. MM patients with higher SETDB1 expression showed higher levels of beta-2 microglobulin (β2M), lactate dehydrogenase (LDH), and bone marrow biopsy plasma cells (BMPC) and lower levels of haemoglobin (HGB). Functional enrichment analysis suggested that SETDB1 could promote cell cycle progression in myeloma. Finally, we observed that SETDB1 was distinctly correlated with tumor immunity in MM. SETDB1 expression in myeloma cells was positively correlated with CD56dim natural killer cells but negatively correlated with infiltrating levels of type17 T helper cells, effector memory CD8 T cells, activated dendritic cells, and natural killer T cells from whole bone marrow (WBM) biopsies. Taken together, these results indicated that SETDB1 could be used as a novel biomarker for predicting the prognosis of MM patients.

The Clinical Significance and Potential Molecular Mechanism of Upregulated CDC28 Protein Kinase Regulatory Subunit 1B in Osteosarcoma

BACKGROUND

CDC28 Protein Kinase Regulatory Subunit 1B (CKS1B) is a member of cyclin-dependent kinase subfamily and the relationship between CKS1B and osteosarcoma (OS) remains to be explored.

METHODS

80 OS and 41 nontumor tissue samples were arranged to conduct immunohistochemistry (IHC) to evaluate CKS1B expression between OS and nontumor samples. The standard mean deviation (SMD) was calculated based on in-house IHC and tissue microarrays and exterior high-throughput datasets for further verification of CKS1B expression in OS. The effect of CKS1B expression on clinicopathological and overall survival of OS patients was measured through public high-throughput datasets, and analysis of immune infiltration and single-cell RNA-seq was applied to ascertain molecular mechanism of CKS1B in OS.

RESULTS

A total of 197 OS samples and 83 nontumor samples (including tissue and cell line) were obtained from in-house IHC, microarrays, and exterior high-throughput datasets. The analysis of integrated expression status demonstrated upregulation of CKS1B in OS (SMD = 1.38, 95% CI [0.52-2.25]) and the significant power of CKS1B expression in distinguishing OS samples from nontumor samples (Area under the Curve (AUC) = 0.89, 95% CI [0.86-0.91]). Clinicopathological and prognosis analysis indicated no remarkable significance but inference of immune infiltration and single-cell RNA-seq prompted that OS patients with overexpressed CKS1B were more likely to suffer OS metastasis while MYC Protooncogene may be the upstream regulon of CKS1B in proliferating osteoblastic OS cells.

CONCLUSIONS

In this study, sufficient evidence was provided for upregulation of CKS1B in OS. The advanced effect of CKS1B on OS progression indicates a foreground of CKS1B as a biomarker for OS.

Role of 1q21 in Multiple Myeloma: From Pathogenesis to Possible Therapeutic Targets

Multiple myeloma (MM) is characterized by an accumulation of malignant plasma cells (PCs) in the bone marrow (BM). The amplification of 1q21 is one of the most common cytogenetic abnormalities occurring in around 40% of de novo patients and 70% of relapsed/refractory MM. Patients with this unfavorable cytogenetic abnormality are considered to be high risk with a poor response to standard therapies. The gene(s) driving amplification of the 1q21 amplicon has not been fully studied. A number of clear candidates are under investigation, and some of them (IL6R, ILF2, MCL-1, CKS1B and BCL9) have been recently proposed to be potential drivers of this region. However, much remains to be learned about the biology of the genes driving the disease progression in MM patients with 1q21 amp. Understanding the mechanisms of these genes is important for the development of effective targeted therapeutic approaches to treat these patients for whom effective therapies are currently lacking. In this paper, we review the current knowledge about the pathological features, the mechanism of 1q21 amplification, and the signal pathway of the most relevant candidate genes that have been suggested as possible therapeutic targets for the 1q21 amplicon.

The survival impact of CKS1B gains or amplification is dependent on the background karyotype and TP53 deletion status in patients with myeloma

Gains or amplification (amp) of chromosome 1q21/CKS1B are reported to be a high-risk factor in myeloma. In this retrospective study, we analyzed the impact of CKS1B gain/amp on overall survival in the context of other genetic aberrations, such as TP53 deletion, FGFR3-IGH, IGH-MAF, MYEOV/CCND1-IGH, and RB1, as well as karyotype. The cohort included 132 myeloma patients with CKS1B gain/amp detected by fluorescence in-situ hybridization. There were 72 men and 60 women with a median age of 65 years (range 39-88 years). A normal, simple, or complex karyotype was observed in 39.5%, 5.4%, and 55% of patients, respectively. "Double hit," defined as CKS1B gain/amp coexisting with TP53 deletion, or "triple hit," defined as double hit plus t(4;14)FGFR3-IGH or t(14;16)IGH-MAF, were identified in 25 patients (18.9%) and five patients (3.8%), respectively. Double and triple hit were highly associated with a complex karyotype (p = 0.02). Ninety-nine patients (99/128, 77.3%) received stem cell transplantation. The median follow-up time was 48.2 months (range 2-104 months); 68 patients (51.5%) died, with a median overall survival of 58.8 months. Multivariate analysis (Cox model) showed that double hit with TP53 deletion (p = 0.0031), triple hit (p = 0.01), and complex karyotype (p = 0.0009) were each independently associated with poorer overall survival. Stem cell transplantation was associated with better overall survival, mainly in patients with a double or triple hit and complex karyotype (p = 0.003). These findings indicate that the inferior outcome of myeloma patients with CKS1B gain/amp is attributable to the high number of high-risk patients in this group. The prognostic impact of CKS1B gain/amp depends on the background karyotype and TP53 status.

Skp2 inhibitor SKPin C1 decreased viability and proliferation of multiple myeloma cells and induced apoptosis

Multiple myeloma (MM) is a malignant neoplasm of plasma, and exhibits several harmful effects including osteolytic injuries, hypercalcemia, and immune dysfunction. Many patients with MM succumb to the underlying malignancy. An S-phase kinase-related protein 2 (Skp2) inhibitor, designated SKPin C1, has been developed and confirmed to have an inhibitory effect on metastatic melanoma cells. This study aimed to determine the effect of SKPin C1 on MM. Normal B lymphocytes, THP-1 cells, and MM U266 and RPMI 8226 cells were exposed to various dosages of SKPin C1 for 48 h. Cell proliferation was determined by MTT, EdU staining, and cell cycle assays. Western blot assays were performed to assess intracellular protein levels of Skp2, p27, and cleaved caspase-3. The amount of ubiquitin attached to p27 was determined using an immunoprecipitation assay. The viability of U266 and RPMI 8226 cells was significantly inhibited by 10 μM SKPin C1 and the inhibitory effect was enhanced with increasing doses of SKPin C1. In contrast, 50 μM SKPin C1 only marginally decreased viability of normal B lymphocytes in 12 h. Skp2 and p27 expression in U266 and RPMI 8226 cells was higher and lower, respectively, than that in the normal B lymphocytes. Treatment with SKPin C1 or Skp2 knockdown increased p27 protein levels in U266 and RPMI 8226 cells by preventing p27 from being ubiquitinated, which slowed the cell cycle, inhibited cell proliferation, and triggered apoptosis. Therefore, this study suggested SKPin C1 as a potent inhibitor against aberrant proliferation and immortalization of MM.

Oncogene-induced senescence: a potential breakpoint mechanism against malignant transformation in plasma cell disorders

Oncogene-induced senescence (OIS) is a cellular tumor-suppressive mechanism present in several premalignant conditions. Here, we analyze the possible impact of OIS on malignant transformation in plasma cell disorders. Tumor samples from 125 patients with different disease stages were analyzed immunohistochemically for expression of senescence markers. Protein expression of cyclin-dependent kinase inhibitor p21^Cip1/Waf1 was significantly higher in smoldering multiple myeloma (SMM) compared to monoclonal gammopathy of undetermined significance (MGUS) (p = .02) or symptomatic multiple myeloma (MM) (p = .005). SMM plasma cells expressing p21^Cip1/Waf1 were negative for Ki67, consistent with senescence. While p27^Kip1 was highly expressed in healthy controls, MGUS and SMM, expression decreased significantly in MM (p = .02). SMM plasma cells displayed a mutually exclusive expression of p21^Cip1/Waf1/p27^Kip1 suggesting compensatory mechanisms of senescence. In conclusion, we found markers of cellular senescence differentially expressed in SMM compared to MGUS and MM supporting the hypothesis of OIS as a breakpoint mechanism against malignant transformation in plasma cell disorders.

CKS1 expression in melanocytic nevi and melanoma

Cyclin-dependent kinase subunit 1 (Cks1) regulates the degradation of p27, an important G1-S inhibitor, which is up regulated by MAPK pathway activation. In this study, we sought to determine whether Cks1 expression is increased in melanocytic tumors and correlates with outcome and/or other clinicopathologic prognostic markers. Cks1 expression was assessed by immunohistochemistry in 298 melanocytic lesions. The frequency and intensity of cytoplasmic and nuclear expression was scored as a labeling index and correlated with clinico-pathological data. Nuclear Cks1 protein was found in 63% of melanocytic nevi, 89% primary and 90% metastatic melanomas with mean labeling index of 7 ± 16, 19 ± 20, and 30 ± 29, respectively. While cytoplasmic Cks1 was found in 41% of melanocytic nevi, 84% primary and 95% metastatic melanomas with mean labeling index of 18 ± 34, 35 ± 34, and 52 ± 34, accordingly. Histologic stepwise model of tumor progression, defined as progression from benign nevi to primary melanomas, to melanoma metastases, revealed a significant increase in nuclear and cytoplasmic Cks1 expression with tumor progression. Nuclear and cytoplasmic Cks1 expression correlated with the presence of ulceration, increased mitotic rate, Breslow depth, Clark level, tumor infiltrating lymphocytes and gender. However, other well-known prognostic factors (age, anatomic site, and regression) did not correlate with any type of Cks1 expression. Similarly, increasing nuclear expression of Cks1 significantly correlated with worse overall survival. Thus, Cks1 expression appears to play a role in the progression of melanoma, where high levels of expression are associated with poor outcome. Cytoplasmic expression of Cks1 might represent high turnover of protein via the ubiquination/proteosome pathway.

[Prognostic value of 1q21 amplification in multiple myeloma]

AIM

To determine the prevalence of amp1q21 and its relationship to the clinical manifestations of multiple myeloma (MM).

SUBJECTS AND METHODS

In December 2009 to March 2016, a total 134 patients aged 30 to 81 years (median 57 years) underwent a pretreatment FISH-study of bone marrow (BM) with centromeric and locus-specific DNA probes to identify amp1q21, t(11;14), t(4;14), t(14;16), t(14;20), t(6;14), trisomies of chromosomes 5, 9, 15, del13q14, del17p13/TP53, and t(8q24)/cMYC. Induction therapy with bortezomib-containing cycles was performed. Autologous stem cell transplantation was carried out in 48 patients. The median follow-up of patients was 19.3 months (3.2-77.4 months). Disease progression was diagnosed in 69 (51.5%) patients; 12 patients also underwent FISH study during disease progression.

RESULTS

At the onset of MM, amp1q21 was detected in 53 (39.6%) patients. The overall 5-year survival rate in patients with amp1q21 was almost 2 times lower than that in those without amp1q21 (43.5 and 79.4%, respectively; p=0.07). The overall 5-year survival rate in patients with one extra copy of 1q21 (only 3 copies) was 67.3%, that in those with 2 or more extra copies of 1q21 (only 4-7 copies) was 20.9% (p=0.0016). Nine (75%) of the 12 patients examined during disease progression were found to have amp1q21: 2 cases were detected in the period of progression to have amp1q21 in its absence at disease onset; 7 cases had amp1q21 both at MM onset and progression; however, the number of copies of 1q21 was unchanged.

CONCLUSION

Аmp1q21 is one of the most common chromosomal abnormalities in patients with new-onset MM and may appear in the course of disease progression. The presence of аmp1q21 is an important prognostic factor and must have to be included in the diagnostic study both at disease onset and progression.

Combination of t(4;14), del(17p13), del(1p32) and 1q21 gain FISH probes identifies clonal heterogeneity and enhances the detection of adverse cytogenetic profiles in 233 newly diagnosed multiple myeloma

Background

Our aim was to set the FISH combination of del(17p13), t(4;14), 1q21 gain and del(1p32), four adverse cytogenetic factors rarely evaluated together, and compare our technical thresholds with those defined in the literature.

Methods

Two hundred thirty-three patients with MM at diagnosis were studied using FISH to target 4 unfavorable cytogenetic abnormalities: 17p13 deletion, t(4;14) translocation, 1p32 deletion and 1q21 gain. Technical thresholds were determined for each probe using isolated CD138-expressing PC from patients without MM.

Results

The FISH analysis identified abnormalities in 79.0% of patients. Del(17p13) was detected in 15.0% of cases, t(4;14) in 11.5%, 1q21 gain in 37.8% and del(1p32) in 8.7%. Adding 1p32/1q21 FISH probes has enabled us to identify adverse cytogenetic profiles in 39.0% of patients without del(17p13) or t(4;14). Clonal heterogeneity was observed in 51.1% of patients as well as an increase in the number of adverse abnormalities when related clones were greater than or equal to 2 (85.1% against 45.6%).

Conclusion

FISH allowed detecting accumulation of adverse abnormalities and clonal heterogeneity in MM with a combination of 4 probes. The impacts of these two parameters need to be evaluated, and could be included in future cytogenetic classifications.

The therapeutic potential of cell cycle targeting in multiple myeloma

Proper cell cycle progression through the interphase and mitosis is regulated by coordinated activation of important cell cycle proteins (including cyclin-dependent kinases and mitotic kinases) and several checkpoint pathways. Aberrant activity of these cell cycle proteins and checkpoint pathways results in deregulation of cell cycle progression, which is one of the key hallmarks of cancer. Consequently, intensive research on targeting these cell cycle regulatory proteins identified several candidate small molecule inhibitors that are able to induce cell cycle arrest and even apoptosis in cancer cells. Importantly, several of these cell cycle regulatory proteins have also been proposed as therapeutic targets in the plasma cell malignancy multiple myeloma (MM). Despite the enormous progress in the treatment of MM the past 5 years, MM still remains most often incurable due to the development of drug resistance. Deregulated expression of the cyclins D is observed in virtually all myeloma patients, emphasizing the potential therapeutic interest of cyclin-dependent kinase inhibitors in MM. Furthermore, other targets have also been identified in MM, such as microtubules, kinesin motor proteins, aurora kinases, polo-like kinases and the anaphase promoting complex/cyclosome. This review will provide an overview of the cell cycle proteins and checkpoint pathways deregulated in MM and discuss the therapeutic potential of targeting proteins or protein complexes involved in cell cycle control in MM.

Outcome of Patients with Multiple Myeloma and CKS1B Gene Amplification after Autologous Hematopoietic Stem Cell Transplantation

The gain/amplification of the CKS1B gene on chromosome 1q21 region is associated with a poor outcome in patients with multiple myeloma (MM). However, there are limited data on the outcome of patients with CKS1B amplification after a single high-dose chemotherapy and autologous hematopoietic stem cell transplantation (auto-HCT). We retrospectively evaluated the outcome of patients with CKS1B amplification who received an auto-HCT between June 2012 and July 2014 at our institution. We identified 58 patients with MM and CKS1B gene amplification detected by fluorescent in situ hybridization (FISH). We compared their outcomes with a propensity score-matched control group of 58 patients without CKS1B amplification who were treated at approximately the same time. The primary objective was to compare the progression-free (PFS) and overall survival (OS) between the CKS1B and the control groups. Stratified log-rank test with the matched pairs as strata and double robust estimation under the Cox model were used to assess the effect of CKS1B gene amplification on PFS or OS in the matched cohort. Patients in the CKS1B and control groups were well matched for age, gender, disease status, year of auto-HCT, response to pretransplantation therapy, and baseline hemoglobin level. In both groups, 57% patients were in first remission and 43% had relapsed disease at auto-HCT. Twenty-seven (47%) patients with CKS1B amplification had concurrent monosomy 13 or 13q deletion; 6 (10%) by conventional cytogenetics only, 16 (28%) by FISH only, and 5 (9%) by both. Median follow-up after auto-HCT was 25.4 months. The median PFS of the CKS1B and the control groups were 15.0 months and 33.0 months (P = .002), respectively. The median OS have not been reached yet. The 2-year OS rates in the CKS1B and the control groups were 62% and 91% (P = .02), respectively. In conclusion, Patients with CKS1B amplification are more likely to have additional high-risk cytogenetic abnormalities and a shorter PFS and OS after an auto-HCT.

FOXM1 is a therapeutic target for high-risk multiple myeloma

The transcription factor forkhead box M1 (FOXM1) is a validated oncoprotein in solid cancers, but its role in malignant plasma cell tumors such as multiple myeloma (MM) is unknown. We analyzed publicly available MM data sets and found that overexpression of FOXM1 prognosticates inferior outcome in a subset (~15%) of newly diagnosed cases, particularly patients with high-risk disease based on global gene expression changes. Follow-up studies using human myeloma cell lines (HMCLs) as the principal experimental model system demonstrated that enforced expression of FOXM1 increased growth, survival and clonogenicity of myeloma cells, whereas knockdown of FOXM1 abolished these features. In agreement with that, constitutive upregulation of FOXM1 promoted HMCL xenografts in laboratory mice, whereas inducible knockdown of FOXM1 led to growth inhibition. Expression of cyclin-dependent kinase 6 (CDK6) and NIMA-related kinase 2 (NEK2) was coregulated with FOXM1 in both HMCLs and myeloma patient samples, suggesting interaction of these three genes in a genetic network that may lend itself to targeting with small-drug inhibitors for new approaches to myeloma therapy and prevention. These results establish FOXM1 as high-risk myeloma gene and provide support for the design and testing of FOXM1-targeted therapies specifically for the FOXM1(High) subset of myeloma.

Jumping Translocations in Myeloid Malignancies Associated With Treatment Resistance and Poor Survival

BACKGROUND

Jumping translocations (JT) are uncommon cytogenetic abnormalities involving nonreciprocal translocations of a single donor chromosome onto 2 or more chromosomes. The clinical characteristics and prognosis of JTs in patients with myeloid malignancies are not well described.

MATERIALS AND METHODS

We searched our cytogenetic database from 2003 to 2014 to identify cases of myeloid malignancies associated with a JT. These cases were cross-referenced with our clinical databases to determine patient characteristics, response to treatment and overall survival.

RESULTS

We identified 10 patients with myeloid malignancies and a JT: 4 cases of acute myeloid leukemia with myelodysplastic syndrome-related changes, 4 cases of myelodysplastic syndrome, and 2 cases of postpolycythemia myelofibrosis. The donor segment was derived from chromosome 1 in every case. The acquisition of a JT was a late occurrence, with a median time to JT development of 24.9 months (range, 0-248 months) from diagnosis. The overall response to treatment was poor, with no patients experiencing a response to conventional chemotherapy or hypomethylating agents. The median overall survival for the group was 9 months (95% confidence interval, 2.5-15.5) after identification of a JT.

CONCLUSION

The acquisition of a JT in patients with myeloid malignancies appears to be a late event and is associated with myelodysplasia. In our series, this was associated with a poor prognosis with a poor response to treatment, disease transformation to acute myeloid leukemia, and short overall survival.

The impact of clone size on the prognostic value of chromosome aberrations by fluorescence in situ hybridization in multiple myeloma

PURPOSE

Accumulating evidence indicates that intratumor heterogeneity is prevalent in multiple myeloma and that a collection of multiple, genetically distinct subclones are present within the myeloma cell population. It is not clear whether the size of clonal myeloma populations harboring unique cytogenetic abnormalities carry any additional prognostic value.

EXPERIMENTAL DESIGN

We analyzed the prognostic impact of cytogenetic aberrations by fluorescence in situ hybridization at different cutoff values in a cohort of 333 patients with newly diagnosed myeloma and 92 patients with relapsed myeloma.

RESULTS

We found that nearly all IgH-related arrangements were observed in a large majority of the purified plasma cells; however, 13q deletion, 17p deletion, and 1q21 amplification appeared in different percentages within the malignant plasma cell population. Based on the size of subclones carrying these cytogenetic aberrations, the patients were divided into four groups: 0%-10%, 10.5%-20%, 20.5%-50%, and >50%. Receiver-operating characteristics analysis was applied to determine the optimal cutoff value with the greatest differential survival and showed that the most powerful clone sizes were 10% for 13q deletion, 50% for 17p deletion, and 20% for 1q21 gains, which provided the best possible cutoffs for predicting poor outcomes.

CONCLUSIONS

Our study indicated that the impact of clone size on prognostic value varies between specific genetic abnormalities. Prognostic value was observed for even a subgroup of plasma cells harboring the cytogenetic aberration of 13q deletion and 1q21 gains; however, 17p deletion displayed the most powerful cutoff for predicting survival only if the predominant clones harbored the abnormality.

Cks1 proteasomal degradation is induced by inhibiting Hsp90-mediated chaperoning in cancer cells

PURPOSE

Cks1, a conformationally heterogenous 9 kDa protein, is markedly overexpressed in cancer cells and contributes to tumor development. Cks1 is an essential component of the SCF-Skp2 ubiquitin ligase complex that targets the Cdk inhibitors p27(Kip1) and p21(Cip1). Cks1 is known to interact with the Hsp90-Cdc37 chaperone machinery, although whether this facilitates its conformational maturation and stability is not known. To test whether abrogating the chaperone function of Hsp90 could destabilize Cks1, we examined the effects of treating different cancer cell lines with the benzoquinone ansamycin 17-allylamino geldanamycin (17-AAG), a compound that selectively binds Hsp90 and potently inhibits its ATP-dependent chaperone activity.

METHODS

The effect of Hsp90 inhibition using 17-AAG on Cks1 protein and associated cell cycle proteins including Skp2, p27(Kip1), p21(Cip1), and Cdk1 in cancer cells was determined by Western blotting. Ubiquitination analysis was carried out by transfecting cells with an HA-ubiquitin plasmid and specifically immunoprecipitating Cks1 to examine polyubiquitinated species. Flow cytometry was utilized to examine the effects of Hsp90 inhibition on cell cycle profiles.

RESULTS

Here, we demonstrate for the first time that inhibition of Hsp90 utilizing 17-AAG destabilizes Cks1 in cancer cells by promoting its ubiquitination and proteasomal degradation. 17-AAG-induced Cks1 depletion was accompanied by concomitant decreases in Skp2 and Cdk1. 17-AAG treatment also induced G2/M accumulation in MCF-7 breast carcinoma cells, and G1 accumulation in the colon carcinoma lines HCT116 and SW620.

CONCLUSIONS

We conclude that perturbing the Hsp90 pathway could provide a useful therapeutic strategy in tumors driven by Cks1 overexpression.

Prognostic value and efficacy evaluation of novel drugs for cytogenetic aberrations in multiple myeloma: a meta-analysis

Cytogenetic abnormalities have emerged as the major novel prognostic factors in multiple myeloma (MM) patients. This meta-analysis comprehensively investigates the association between the cytogenetic abnormalities and survival of MM patients. We searched the PubMed, EMBASE, SCOPUS, and Cochrane databases for articles published until February, 2014. Thirty eligible studies involving 10276 patients were included to examine the association of three chromosomal abnormalities, t (4; 14), del (17p), and Amp (1q21), with survival in MM patients. The main outcome measures were progression-free survival (PFS) and overall survival (OS). Individuals with t (4; 14), del (17p), and Amp (1q21) had low OS and PFS. In a subgroup analysis for therapy regimen, lenalidomide- and bortezomib-based therapies increased the PFS of patients with Amp (1q21) (HR=1.50, 95% CI=0.95-2.36, p=0.084) and t (4; 14) (HR=1.38, 95% CI=0.90-2.11, p=0.143). The presence of del (17p) elicited no significant influence on the prognosis of patients under different therapy regimens. Our meta-analysis provides globally quantifiable confirmation of the adverse prognostic value of t (4; 14), del (17p), and Amp (1q21) in OS and PFS for MM patients. Lenalidomide- and bortezomib-based therapies were partly conducive to improve the prognosis of individuals with t (4; 14). Bortezomib-based therapy can partly improve the PFS of patients with Amp (1q21).

Quantitative analysis of CKS1B mRNA expression and copy number gain in patients with plasma cell disorders

In this study, we have examined CKS1B gene expression and copy number in a total of 114- patients at diagnosis: 83 with multiple myeloma (MM) and 31 with monoclonal gammopathy of undetermined significance (MGUS). Results were correlated with cytogenetics, FISH and clinical characteristic. Significant CKS1B mRNA levels in MM compared to MGUS cases (p<0.048) were detected. In MM, the frequency of 1q21 (CKS1B) copy gain was significantly higher in cases with abnormal karyotype compared to patients with normal karyotype (p=0.021). Global analysis showed a positive correlation between CKS1B expression and 1q21 copy number (p<0.0001). No association between CKS1B mRNA expression and clinical parameters was found. However, a significantly higher level of β2 microglobulin in cases with 1q21 gains than those without (p=0.0094) was observed. Overall survival was shorter in cases with 1q21 gain compared to those with normal 1q21 region (p=0.0082). Our results suggest a role for CKS1B in the multiple step process of progression of MGUS to MM and show that CKS1B copy gain has a more significant prognostic value than its overexpression. This adverse impact on survival probably reflects the genetic instability associated to chromosome 1q alterations resulting in a more aggressive behavior of the disease.

Cks1: Structure, Emerging Roles and Implications in Multiple Cancers

Deregulation of the cell cycle results in loss of normal control mechanisms that prevent aberrant cell proliferation and cancer progression. Regulation of the cell cycle is a highly complex process with many layers of control. One of these mechanisms involves timely degradation of CDK inhibitors (CKIs) like p27^Kip1 by the ubiquitin proteasomal system (UPS). Cks1 is a 9 kDa protein which is frequently overexpressed in different tumor subtypes, and has pleiotropic roles in cell cycle progression, many of which remain to be fully characterized. One well characterized molecular role of Cks1 is that of an essential adaptor that regulates p27^Kip1 abundance by facilitating its interaction with the SCF-Skp2 E3 ligase which appends ubiquitin to p27^Kip1 and targets it for degradation through the UPS. In addition, emerging research has uncovered p27^Kip1-independent roles of Cks1 which have provided crucial insights into how it may be involved in cancer progression. We review here the structural features of Cks1 and their functional implications, and also some recently identified Cks1 roles and their involvement in breast and other cancers.

Additional genetic abnormalities significantly worsen poor prognosis associated with 1q21 amplification in multiple myeloma patients

We investigated the prognostic value of amp(1q21) alone and in combination with other abnormalities in newly diagnosed myeloma patients. The study group consisted of 104 patients treated with various induction regimens, mostly thalidomide based (87 patients). Amp(1q21) was detected in 49 (47.1%) of patients; in 26 (25.0%) cases, it was combined with del(13q14), in 7 (6.7%) with del(17p13) and in 15 (14.4%) with t(4;14)(p16;q32). The response rate was significantly better in amp(1q21)-negative than in amp(1q21)-positive patients (74.5% vs 55.1%, p = 0.025; complete response 18.2% vs 4.1%, p = 0.024). The median progression-free survival (PFS) was 33.9 months in patients without amp(1q21) and 10.3 months with this aberration (p = 0.002). The presence of additional abnormalities resulted in significantly shortened PFS when compared with patients with isolated amp(1q21): coexisting del(13q14) resulted in 7.8 vs 29.0 months of PFS (p = 0.024) and del(17p13) resulted in 4.0 vs 24.9 months of PFS (p = 0.034). The presence of amp(1q21) significantly influenced overall survival (OS) as well as PFS resulting in the median OS of 26.6 vs 62.4 months (p = 0.018) in patients without amp(1q21). The presence of additional genetic abnormalities significantly affected OS when compared with patients carrying isolated amp(1q21): for del(13q14) 18.9 vs 58.4 months (p = 0.004) and for del(17p13) 12.0 vs 46.5 months (p = 0.036). On multivariate analysis amp(1q21), del(13q14) and del(17p13) were found to be an independent adverse predictors of shorter PFS and OS. Our results showed that the presence of amp(1q21) was associated with poor prognosis. Moreover additional genetic abnormalities made PFS and OS further shortened.

Cks1 is required for tumor cell proliferation but not sufficient to induce hematopoietic malignancies

The Cks1 component of the SCF(Skp2) complex is necessary for p27(Kip1) ubiquitylation and degradation. Cks1 expression is elevated in various B cell malignancies including Burkitt lymphoma and multiple myeloma. We have previously shown that loss of Cks1 results in elevated p27(Kip1) levels and delayed tumor development in a mouse model of Myc-induced B cell lymphoma. Surprisingly, loss of Skp2 in the same mouse model also resulted in elevated p27(Kip1) levels but exhibited no impact on tumor onset. This raises the possibility that Cks1 could have other oncogenic activities than suppressing p27(Kip1). To challenge this notion we have targeted overexpression of Cks1 to B cells using a conditional retroviral bone marrow transduction-transplantation system. Despite potent ectopic overexpression, Cks1 was unable to promote B cell hyperproliferation or B cell malignancies, indicating that Cks1 is not oncogenic when overexpressed in B cells. Since Skp2 overexpression can drive T-cell tumorigenesis or other cancers we also widened the quest for oncogenic activity of Cks1 by ubiquitously expressing Cks1 in hematopoetic progenitors. At variance with c-Myc overexpression, which caused acute myeloid leukemia, Cks1 overexpression did not induce myeloproliferation or leukemia. Therefore, despite being associated with a poor prognosis in various malignancies, sole Cks1 expression is insufficient to induce lymphoma or a myeloproliferative disease in vivo.

Cyclin kinase subunit 1B nuclear expression predicts an adverse outcome for patients with relapsed/refractory multiple myeloma treated with bortezomib

Amplification of cyclin kinase subunit 1B gene on chromosome 1q21 resulting in overexpression of cyclin kinase subunit 1B has been associated with disease progression in multiple myeloma. Bortezomib is a proteasome inhibitor that induces apoptosis in various cancer cells and has been shown to be effective as a salvage therapy for relapsed/refractory multiple myeloma. Our group has recently reported the adverse effect of 1q21 gains in relapsed and refractory multiple myeloma treated with bortezomib. However, whether nuclear cyclin kinase subunit 1B protein expression correlates with 1q21 gains and has prognostic value in patients with multiple myeloma receiving bortezomib regimen remains unclear. We, therefore, evaluated the nuclear expression of cyclin kinase subunit 1B protein in patients with relapsed/refractory multiple myeloma undergoing bortezomib therapy by immunohistochemistry. The 1q21 amplification status of the same cohort was examined by interphase cytoplasmic immunoglobulin fluorescence in situ hybridization. Of 60 cases, 19 (32%) were positive for cyclin kinase subunit 1B nuclear expression by immunohistochemistry. Seventeen (89%) of the immunohistochemistry-positive cases had 1q21 gain detected by cytoplasmic immunoglobulin fluorescence in situ hybridization, and 17 (77%) of the 22 cases with 1q21 gain showed increased cyclin kinase subunit 1B protein expression. cyclin kinase subunit 1B expression and 1q21 gain were strongly correlated (P < .0001). There was no significant difference in response rate between patients with and without cyclin kinase subunit 1B nuclear expression. However, patients with cyclin kinase subunit 1B expression had a significantly shorter progression-free survival (1.9 versus 5.6 months; P < .0001) and overall survival (4.9 versus 22.4 months; P = .012) compared with those without cyclin kinase subunit 1B expression. Our results indicated that cyclin kinase subunit 1B nuclear expression detected by immunohistochemistry is an adverse prognostic factor for patients with multiple myeloma treated with bortezomib therapy.

Clinical impact of chromosomal aberrations in multiple myeloma

Chromosomal aberrations are frequently found in multiple myeloma cells and play a major role in patient outcome and management of the disease. The most important chromosomal aberrations associated with poor outcome are del(17p), t(4;14), t(14;16) and t(14;20). Others that may be associated with adverse prognosis include amp(1)(q21), del(1p32), del(13), del(8p21) and hypodiploidy. Many chromosomal aberrations have no or uncertain impact; for example, t(11;14), t(8;14) and hyperdiploidy. Attempts have been made to overcome the negative prognostic impact of chromosomal aberrations using autologous or allogeneic transplantation or new immunomodulatory drugs such as thalidomide, lenalidomide and the proteasome inhibitor bortezomib, but the results are controversial. Data suggest that allogeneic transplantation and treatment with bortezomib or lenalidomide may help to overcome the negative effect of del(13) on prognosis, whereas bortezomib may have some influence on reducing the impact of del(17p), t(4;14) and t(14;16). Chromosome analysis should always be performed at diagnosis of multiple myeloma to improve the prediction of outcome and to aid treatment decision-making.