Differences in proliferative capacity of primary human acute myelogenous leukaemia cells are associated with altered gene expression profiles and can be used for subclassification of patients

OBJECTIVES

Proliferative capacity of acute myelogenous leukaemia (AML) blasts is important for leukaemogenesis, and we have investigated whether proliferative capacity of primary human AML cells could be used for subclassification of patients.

MATERIALS AND METHODS

In vitro proliferative capacity of AML cells derived from two independent groups was investigated. Cells were cultured under highly standardized conditions and proliferation assayed by (3) H-thymidine incorporation after seven days culture. Patients were subclassified by clustering models, and gene expression profile was examined by microarray analyses.

RESULTS

Based on proliferative capacity of the AML cells, three different patient clusters were identified: (i) autocrine proliferation that was increased by exogenous cytokines; (ii) detectable proliferation only in presence of exogenous cytokines; and (iii) low or undetectable proliferation even in presence of exogenous cytokines. Patients with highest proliferative capacity cells had no favourable prognostic impact by NPM-1 mutation. Analysis of gene expression profiles showed that the most proliferative cells generally had altered expression of genes involved in regulation of transcription/RNA functions, whereas patients with high proliferative capacity and internal tandem duplications (ITDs) in the FLT3 cytokine receptor gene had altered expression of several molecules involved in cytoplasmic signal transduction.

CONCLUSIONS

In vitro proliferative capacity of primary human AML cells was considerably variable between patients and could be used to identify biologically distinct patient subsets.

KRAS gene amplification and overexpression but not mutation associates with aggressive and metastatic endometrial cancer

BACKGROUND

Three quarter of endometrial carcinomas are treated at early stage. Still, 15 to 20% of these patients experience recurrence, with little effect from systemic therapies. Homo sapiens v-Ki-ras2 Kirsten rat sarcoma viral oncogenes homologue (KRAS) mutations have been reported to have an important role in tumorigenesis for human cancers, but there is limited knowledge regarding clinical relevance of KRAS status in endometrial carcinomas.

METHODS

We have performed a comprehensive and integrated characterisation of genome-wide expression related to KRAS mutations and copy-number alterations in primary- and metastatic endometrial carcinoma lesions in relation to clinical and histopathological data. A primary investigation set and clinical validation set was applied, consisting of 414 primary tumours and 61 metastatic lesions totally.

RESULTS

Amplification and gain of KRAS present in 3% of the primary lesions and 18% of metastatic lesions correlated significantly with poor outcome, high International Federation of Gynaecology and Obstetrics stage, non-endometrioid subtype, high grade, aneuploidy, receptor loss and high KRAS mRNA levels, also found to be associated with aggressive phenotype. In contrast, KRAS mutations were present in 14.7% of primary lesions with no increase in metastatic lesions, and did not influence outcome, but was significantly associated with endometrioid subtype, low grade and obesity.

CONCLUSION

These results support that KRAS amplification and KRAS mRNA expression, both increasing from primary to metastatic lesions, are relevant for endometrial carcinoma disease progression.

Loss of GPER identifies new targets for therapy among a subgroup of ERα-positive endometrial cancer patients with poor outcome

BACKGROUND

The G protein-coupled oestrogen receptor, GPER, has been suggested as an alternative oestrogen receptor. Our purpose was to investigate the potential of GPER as a prognostic and predictive marker in endometrial carcinoma and to search for new drug candidates to improve treatment of aggressive disease.

MATERIALS AND METHOD

A total of 767 primary endometrial carcinomas derived from three patient series, including an external dataset, were studied for protein and mRNA expression levels to investigate and validate if GPER loss identifies poor prognosis and new targets for therapy in endometrial carcinoma. Gene expression levels, according to ERα/GPER status, were used to search the connectivity map database for small molecular inhibitors with potential for treatment of metastatic disease for receptor status subgroups.

RESULTS

Loss of GPER protein is significantly correlated with low GPER mRNA, high FIGO stage, non-endometrioid histology, high grade, aneuploidy and ERα loss (all P-values ≤0.05). Loss of GPER among ERα-positive patients identifies a subgroup with poor prognosis that until now has been unrecognised, with reduced 5-year survival from 93% to 76% (P=0.003). Additional loss of GPER from primary to metastatic lesion counterparts further supports that loss of GPER is associated with disease progression.

CONCLUSION

These results support that GPER status adds clinically relevant information to ERα status in endometrial carcinoma and suggest a potential for new inhibitors in the treatment of metastatic endometrial cancers with ERα expression and GPER loss.

High BMI is significantly associated with positive progesterone receptor status and clinico-pathological markers for non-aggressive disease in endometrial cancer

BACKGROUND

Endometrial cancer incidence is increasing in industrialised countries. High body mass index (BMI, kg  m(-2)) is associated with higher risk for disease. We wanted to investigate if BMI is related to clinico-pathological characteristics, hormone receptor status in primary tumour, and disease outcome in endometrial cancer.

PATIENTS AND METHODS

In total, 1129 women primarily treated for endometrial carcinoma at Haukeland University Hospital during 1981-2009 were studied. Body mass index was available for 949 patients and related to comprehensive clinical and histopathological data, hormone receptor status in tumour, treatment, and follow-up.

RESULTS

High BMI was significantly associated with low International Federation of Gynaecology and Obstetrics (FIGO) stage, endometrioid histology, low/intermediate grade, and high level of progesterone receptor (PR) mRNA by qPCR (n=150; P=0.02) and protein expression by immunohistochemistry (n=433; P=0.003). In contrast, oestrogen receptor (ERα) status was not associated with BMI. Overweight/obese women had significantly better disease-specific survival (DSS) than normal/underweight women in univariate analysis (P=0.035). In multivariate analysis of DSS adjusting for age, FIGO stage, histological subtype, and grade, BMI showed no independent prognostic impact.

CONCLUSION

High BMI was significantly associated with markers of non-aggressive disease and positive PR status in a large population-based study of endometrial carcinoma. Women with high BMI had significantly better prognosis in univariate analysis of DSS, an effect that disappeared in multivariate analysis adjusting for established prognostic markers. The role of PR in endometrial carcinogenesis needs to be further studied.

Highly infiltrative brain tumours show reduced chemosensitivity associated with a stem cell-like phenotype

AIMS

Cancer stem-like cells might have important functions in chemoresistance. We have developed a model where highly infiltrative brain tumours with a stem-like phenotype were established by orthotopic transplantation of human glioblastomas to immunodeficient rats. Serial passaging gradually transformed the tumours into a less invasive and more angiogenic phenotype (high-generation tumours). The invasive phenotype (low-generation tumours) was characterized by an increase in stem cell markers and increased phosphorylation of kinases in the phosphatidylinositol 3-kinase (PI3K)/AKT pathway. These markers were reduced in the serially passaged vascular tumours. The present study was aimed at investigating how the two phenotypes responded in vitro to doxorubicin, a clinically potent cytotoxic drug for solid tumours.

METHODS

Biopsy spheroids were implanted and passaged intracranially in nude rats. Gene expression and protein analyses were performed, and drug sensitivity was assessed.

RESULTS

Microarray analysis revealed gene ontology categories connected to developmental aspects and negative regulators of differentiation, especially in the infiltrative stem cell-like tumours. The highly invasive stem-like phenotype was chemoresistant compared with the angiogenic phenotype. By interfering with the PI3K it was possible to sensitize tumour spheroids to chemotherapy. Real-time quantitative polymerase chain reaction showed downregulation of the stem cell markers Nestin and Musashi-1 in low-generation biopsy spheroids following PI3K inhibition.

CONCLUSIONS

Highly invasive tumours with a stem-like phenotype are more chemoresistant than angiogenic tumours derived from the same patients. We suggest that treatment resistance in glioblastomas can be related to PI3K/AKT activity in stem-like tumour cells, and that targeted interference with the PI3K/AKT pathway might differentiate and sensitize this subpopulation to chemotherapy.

Integrated genomic profiling of endometrial carcinoma associates aggressive tumors with indicators of PI3 kinase activation

Although 75% of endometrial cancers are treated at an early stage, 15% to 20% of these recur. We performed an integrated analysis of genome-wide expression and copy-number data for primary endometrial carcinomas with extensive clinical and histopathological data to detect features predictive of recurrent disease. Unsupervised analysis of the expression data distinguished 2 major clusters with strikingly different phenotypes, including significant differences in disease-free survival. To identify possible mechanisms for these differences, we performed a global genomic survey of amplifications, deletions, and loss of heterozygosity, which identified 11 significantly amplified and 13 significantly deleted regions. Amplifications of 3q26.32 harboring the oncogene PIK3CA were associated with poor prognosis and segregated with the aggressive transcriptional cluster. Moreover, samples with PIK3CA amplification carried signatures associated with in vitro activation of PI3 kinase (PI3K), a signature that was shared by aggressive tumors without PIK3CA amplification. Tumors with loss of PTEN expression or PIK3CA overexpression that did not have PIK3CA amplification also shared the PI3K activation signature, high protein expression of the PI3K pathway member STMN1, and an aggressive phenotype in test and validation datasets. However, mutations of PTEN or PIK3CA were not associated with the same expression profile or aggressive phenotype. STMN1 expression had independent prognostic value. The results affirm the utility of systematic characterization of the cancer genome in clinically annotated specimens and suggest the particular importance of the PI3K pathway in patients who have aggressive endometrial cancer.

Low BMI-1 expression is associated with an activated BMI-1-driven signature, vascular invasion, and hormone receptor loss in endometrial carcinoma

We studied the expression of polycomb group (PcG) protein BMI-1 in a large population-based patient series of endometrial carcinomas in relation to clinical and molecular phenotype. Also, 57 fresh frozen endometrial carcinomas were studied for the relationship between BMI-1 protein expression, BMI-1 mRNA level, and activation of an 11-gene signature reported to represent a BMI-1-driven pathway. BMI-1 protein expression was significantly weaker in tumours with vascular invasion (P<0.0001), deep myometrial infiltration (P=0.004), and loss of oestrogen receptor (ER) (P<0.0001) and progesterone receptors (PR) (P=0.03). Low BMI-1 protein expression was highly associated with low BMI-1 mRNA expression (P=0.002), and similarly low BMI-1 mRNA expression correlated significantly with vascular invasion, ER and PR loss, and histologic grade 3. In contrast, activation of the reported 11-gene signature, supposed to represent a BMI-1-driven pathway, correlated with low mRNA expression of BMI-1 (P<0.001), hormone receptor loss, presence of vascular invasion, and poor prognosis. We conclude that BMI-1 protein and mRNA expression are significantly correlated and that BMI-1 expression is inversely associated with activation of the 11-gene signature. Loss of BMI-1 seems to be associated with an aggressive phenotype in endometrial carcinomas.