Loss of expression of the PTEN gene protein product is associated with poor outcome in breast cancer.

INTRODUCTION: The PTEN gene, a candidate tumor suppressor, is localized to chromosome 10q23 and shares extensive homology with cytoskeletal proteins auxilin and tensin. A high frequency of mutations at the PTEN locus has been described in a variety of neoplasms including breast cancer. However, the role of PTEN alternations and its association with outcome variables in breast neoplasia is not well established. DESIGN: Formalin-fixed paraffin embedded tissues from 151 women (mean age 62 years, range 26-98) with primary diagnosis of invasive breast cancer were evaluated for PTEN protein expression by automated immunohistochemical methods. Slides were scored semi-quantitatively based on staining intensity and distribution, and results were compared with clinical pathologic parameters. The mean follow-up was 56 months (range 1-169). RESULTS: Seventy-three (48%) of 151 breast tumors had loss of PTEN protein expression. On univariate analysis, loss of PTEN expression (P =.034), stage (P <.0001), node positive (P <.0001), and tumor grade (P =.002) were associated with disease-related death. Loss of PTEN expression also predicted lymph node metastasis (P <.0001), and correlated with loss of estrogen receptor staining (P =.040). Loss of PTEN did not correlate with stage, tumor grade, disease recurrence, or loss of progesterone receptor [although a trend was seen (P =.092). On multivariate analysis, stage (P <.0001), lymph node metastasis (P <.0001), and tumor grade (P =.002) correlated with survival. CONCLUSION: Loss of PTEN protein expression occurs commonly in breast cancer and correlates with disease related death, lymph node metastasis, and loss of estrogen receptor staining. Our results support the proposed role of PTEN as a candidate tumor suppressor in breast cancer and suggest a need for further study of this marker.

Topoisomerase IIalpha expression in breast cancer: correlation with outcome variables.

Topoisomerase IIalpha (topo IIalpha) plays a key role in DNA replication and is a target for multiple chemotherapeutic agents. In breast cancer, topo II expression has been linked to cell proliferation and HER2/neu protein overexpression. However, its relationship with outcome variables is not well established. Formalin-fixed, paraffin-embedded primary breast cancers from 184 women (mean age, 60 years) were stained for topo II by automated immunohistochemistry. A topo II expression index (TI) was determined by counting the number of positive cells per high-power field and calculating an overall mean number of positive cells per high-power field. Tumors with a TI of more than 1 were considered positive, and those with a TI of 1 or less were considered negative. A cell proliferation index was determine d by automated immunohistochemistry using the MIB-1 antibody in an identical technique. HER-2/neu gene amplification (HER-2 amp) was determined by automated fluorescence in situ hybridization using the Ventana unique sequence probe. Fifty-nine (32%) of the tumors had a TI greater than 1. On univariate analysis, increased topo II expression correlated with decreased patient survival (p = .001), advanced tumor stage (p = .034), lymph node metastasis (p = .018), and HER-2 amp (p = .016). Tumor stage (p < .0001), node-positive status (p < .0001), tumor grade (p = .025), HER-2 amp (p < .0001), and MIB-1 overexpression (p = .002) also correlated with survival on univariate analysis. Topo II expression did not correlate with tumor size, grade, estrogen receptor/progesterone receptor status, or disease recurrence. On multivariate analysis, stage (p < .0001), lymph node metastasis (p < .0001), and tumor grade (p = .002) all independently predicted disease-related death. Increased topo II expression is associated with an aggressive form of breast cancer featuring HER-2 amp and predicts disease-related death, lymph node metastasis, and advanced tumor stage.

Photosynthetic decline and pigment loss during autumn foliar senescence in western larch (Larix occidentalis).

We measured needle pigment content and photosynthetic rates of 1-year-old western larch (Larix occidentalis Nutt.) during autumn foliar senescence. Chlorophyll (Chl) and carotenoid (xanthophyll + b-carotene) contents of needles declined 11 and 17%, respectively, before CO(2) assimilation rate began to decline. Chlorophyll a/b ratio, Chl/carotenoid ratio, photochemical efficiency (F(v)/F(m)), and photochemical quenching did not begin to decline until late in senescence. Internal CO(2)/ambient CO(2) did not change during needle yellowing. In seedlings in warmed soil (average 3 degrees C above natural conditions), the decline in needle chlorophyll content was delayed by 10 days and the decline in CO(2) assimilation rate was delayed by 5 days, compared with seedlings in soil at ambient temperature. In seedlings exposed to an extended 16-h photoperiod, the decline in needle chlorophyll content was delayed by 32 days, and the decline in CO(2) assimilation rate was delayed by 21 days, compared with seedlings exposed to natural day lengths. In addition to delaying the onset of needle senescence, the treatments affected the sequence of events during senescence. Differences among treatment groups provide evidence that the onset of pigment loss and photosynthetic decline and the sequence of events during needle senescence are affected by soil temperature and day length.

Effect of photon flux density on carbon assimilation and chlorophyll a fluorescence of cold-stored white spruce and lodgepole pine seedlings.

White spruce (Picea glauca (Moench.) Voss) and lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) seedlings previously held in dark, frozen storage (-2 degrees C) for 2.5 or 6 months, and nursery-grown white spruce seedlings lifted in summer were exposed to photon flux densities (PFDs) similar to those that might be encountered at planting. Photosynthetic gas exchange and chlorophyll a (chl a) fluorescence were examined in cold-stored and summer-lifted seedlings before and after a 9 h-exposure to artificial illumination of high PFD (2000 micro mol m(-2) s(-1)) or low PFD (ca. 500 micro mol m(-2) s(-1)), and during exposure to 400 micro mol m(-2) s(-1) for 4-9 days. In the 2.5-month-stored and summer-lifted seedlings, the high-PFD treatment caused a small decrease in carbon fixation and a large decrease in the ratio of variable to maximum fluorescence (F(v)/F(m)) relative to the effect of the low-PFD treatment. In contrast, in the 6-month-stored seedlings the high-PFD treatment caused a significant decrease in rate of light-saturated carbon fixation but little decrease in F(v)/F(m) relative to the effect of the low-PFD treatment, indicating that the mechanisms for maintaining integrity of the photochemical apparatus had changed during the storage interval.