Prognostic value of INPP4B protein immunohistochemistry in ovarian cancer.

PURPOSE OF INVESTIGATION: Ovarian cancer is associated with poor prognosis and altered protein expression patterns may be useful for identifying patients likely to have poor disease outcomes. The impact of altered INPP4B protein expression on prognosis is unclear. The aim of this study was to evaluate the implication of INPP4B expression changes in a large series of ovarian cancer tissue samples. MATERIALS AND METHODS: Tissue microarrays were constructed from 599 epithelial ovarian tumors and stained with antibodies for INPP4B, p53, and PTEN. Proportional hazard models were used to estimate survival hazard ratios (HRs) associated with altered protein expression. RESULTS: Seventy-nine percent of the ovarian cancers demonstrated loss of INPP4B, whereas 53% showed aberrant p53 expression (i.e., complete loss of p53 or over-expression of p53) and 8% showed loss of PTEN. INPP4B was frequently lost in serous and endometrioid cancer subtypes, aberrant p53 expression was most common among serous subtype, and loss of PTEN was most common among endometrioid tumors (p for all three proteins across histologic subtypes ≤ 0.0001). INPP4B loss or aberrant p53 expression were both associated with increased mortality (HR = 1.84; 95% CI 1.27 - 2.68 and HR = 3.10; 95% CI 2.33 - 4.11, respectively); however, in multivariate models, only the relationship with p53 achieved statistical significance (HR = 1.20; 95% CI 0.82 - 1.76 for INPP4B and HR = 1.73; 95% CI 1.28 - 2.34 for p53). Conclusion: The INPP4B protein is frequently lost in serous and endometrioid subtypes of ovarian cancer. A possible prognostic role of INPP4B for endometrioid ovarian tumors requires further evaluation.

INPP4B overexpression is associated with poor clinical outcome and therapy resistance in acute myeloid leukemia.

In this study, we investigated the role of inositol polyphosphate-4-phosphatase, type-II (INPP4B) in acute myeloid leukemia (AML). We observed that AML patients with high levels of INPP4B (INPP4B(high)) had poor response to induction therapy, shorter event-free survival and shorter overall survival. Multivariate analyses demonstrated that INPP4B(high) was an independent predictor of poor prognosis, significantly improving current predictive models, where it outperformed conventional biomarkers including FLT3-ITD and NPM1. Furthermore, INPP4B(high) effectively segregated relative risk in AML patients with normal cytogenetics. The role of INPP4B on the biology of leukemic cells was assessed in vitro. Overexpression of INPP4B in AML cell lines enhanced colony formation potential, recapitulated the chemotherapy resistance observed in AML patients and promoted proliferation in a phosphatase-dependent, and Akt-independent manner. These findings reveal that INPP4B(high) has an unexpected role consistent with oncogenesis in AML, in contrast to its previously reported tumor-suppressive role in epithelial cancers. Overall, we propose that INPP4B is a novel prognostic biomarker in AML that has potential to be translated into clinical practice both as a disease marker and therapeutic target.

BRCA1 mRNA levels following a 4-6-week intervention with oral 3,3'-diindolylmethane.

BACKGROUND: Haploinsufficiency may contribute to the development of breast cancer among women with a BRCA1 mutation. Thus, interventions that enhance BRCA1 expression may represent avenues for prevention. Studies have shown that 3,3'-diindolylmethane (DIM) can upregulate BRCA1 expression in breast cancer cells. This has yet to be demonstrated in vivo. METHODS: We conducted a study to evaluate the ability of oral DIM to upregulate BRCA1 mRNA expression in white blood cells. A total of 18 women were enroled in the study, including 13 BRCA1 mutation carriers who received 300 mg per day of Rx Balance BioResponse DIM for 4-6 weeks (intervention group) and 5 BRCA1 mutation carriers who did not take DIM (control group). BRCA1 mRNA expression was assessed at baseline and at 4-6 weeks by real-time, quantitative PCR and the relative change in BRCA1 mRNA expression (that is, 2(-ΔΔCT)) was calculated. RESULTS: The relative change in BRCA1 mRNA expression among women in the intervention group achieved borderline significance (P paired t-test=0.05). In the intervention group, BRCA1 mRNA expression increased in 10 of the participants, decreased in 2 and remained unchanged in 1 of the participants following DIM intervention (P sign test=0.02). On average, women in the intervention group experienced a 34% increase in BRCA1 mRNA expression (range -24 to 194%). There was no significant difference in the relative change in BRCA1 mRNA expression among women in the control group (P paired t-test=0.45). CONCLUSIONS: Under the tested conditions, oral DIM was associated with an increase in BRCA1 mRNA expression in women with a BRCA1 mutation. The possibility of mitigating the effect of an inherited deleterious BRCA1 mutation by increasing the physiologic expression of the gene and normalising protein levels represents a clinically important paradigm shift in the prevention strategies available to these high-risk women. Future studies with a larger sample size and higher doses of DIM are warranted.

CD95 apoptosis resistance in certain cells can be overcome by noncanonical activation of caspase-8.

CD95 apoptosis resistance of tumor cells is often acquired through mutations in the death domain (DD) of one of the CD95 alleles. Furthermore, Type I cancer cells are resistant to induction of apoptosis by soluble CD95 ligand (CD95L), which does not induce efficient formation of the death-inducing signaling complex (DISC). Here, we report that tumor cells expressing a CD95 allele that lacks a functional DD, splenocytes from heterozygous lpr(cg) mice, which express one mutated CD95 allele, and Type I tumor cells stimulated with soluble CD95L can all die through CD95 when protein synthesis or nuclear factor kappa B is inhibited. This noncanonical form of CD95-mediated apoptosis is dependent on the enzymatic activity of procaspase-8 but does not involve fully processed active caspase-8 subunits. Our data suggest that it is possible to overcome the CD95 apoptosis resistance of many tumor cells that do not efficiently form a DISC through noncanonical activation of the caspase-8 proenzyme.

Role of proteasomal degradation in the cell cycle-dependent regulation of DNA topoisomerase IIalpha expression.

1DNA topoisomerase II (topo II) is a nuclear enzyme that modifies DNA topology and also serves as a target to mediate the cytotoxicity of several antineoplastic agents. Several reports have demonstrated that a reduction of topo II is associated with reduced sensitivity to these agents. Topo II exists as two isoforms in mammalian cells: topo IIalpha and topo IIbeta. In MCF-7 cells, the half-life (mean +/- SEM) values of topo IIalpha and topo IIbeta in situ were 6.6 +/- 0.3 and 17.6 +/- 2.3 hr, respectively, as determined by [(35)S]methionine/cysteine pulse-chase analysis. Degradation of topo IIalpha in situ was abrogated by the presence of proteasome inhibitors, and the relative activities were carbobenzoxy-leucyl-leucyl-leucinal (MG132) > carbobenzoxy-leucyl-leucyl-norvalinal (MG115) > ALLN congruent with lactacystin. ATP-dependent degradation of topo IIalpha, but not topo IIbeta, was observed in extracts of asynchronously dividing HeLa and MCF-7 cells. Furthermore, degradation of topo IIalpha was abrogated by the proteasome inhibitors MG132 and MG115, but not by lactacystin, in extracts of asynchronously dividing MCF-7 cells. Finally, degradation of topo IIalpha, but not topo IIbeta, was observed to occur in a cell cycle-dependent fashion, in extracts of synchronized HeLa cells, with maximal loss of the alpha isoform occurring 2 hr after release from mitotic arrest. This degradation of topo IIalpha appeared to be facilitated by an ATP-dependent activity. Furthermore, high molecular weight bands (>200 kDa), which may represent polyubiquitinated-topo IIalpha conjugates, were also detected in extracts of synchronized HeLa cells. This study provides evidence for a role of the ubiquitin-proteasome pathway in the cell cycle-dependent regulation of topo IIalpha expression.

p53 gene status and chemosensitivity of childhood acute lymphoblastic leukemia cells to adriamycin.

The role of p53 as a determinant of sensitivity of ten childhood acute lymphoblastic leukemia (ALL) cell lines to Adriamycin (ADR) was investigated. ADR-sensitive cell lines were found to have wild-type (wt) p53, whereas resistant cell lines contained point mutations in the gene. The basal level of wt p53 protein in sensitive cells was lower than that of mutant p53 in resistant cells, however, after ADR treatment a 6- to 20-fold dose-dependent increase in wt p53 was observed, whereas mutant p53 increased only twofold. The percentage of apoptotic cells in ADR-sensitive lines with wt p53 ranged from 43 to 93% following ADR treatment, whereas that in resistant lines with mutant p53 was only 8-13%. The ratio of constitutive levels of Bax/Bcl-2 was significantly higher in cells containing wt p53 than in cells with mutant p53. These results suggest that p53 gene status and the ability of p53 to induce apoptosis may be determinants of sensitivity to ADR in childhood ALL cells.