Philippe Bougnoux

Improving outcome of chemotherapy of metastatic breast cancer by docosahexaenoic acid: a phase II trial

Background:Breast cancer becomes lethal when visceral metastases develop. At this stage, anti-cancer treatments aim at relieving symptoms and delaying death without resulting in additional toxicity. On the basis of their differential anti-oxidant defence level, tumour cells can be made more sensitive to chemotherapy than non-tumour cells when membrane lipids are enriched with docosahexaenoic acid (DHA), a peroxidisable and oxidative-stress-inducing lipid of marine origin.Methods:This open-label single-arm phase II study evaluated the safety and efficacy (response rate), as primary end points, of the addition of 1.8 g DHA daily to an anthracycline-based chemotherapy (FEC) regimen in breast cancer patients (n=25) with rapidly progressing visceral metastases. The secondary end points were time to progression (TTP) and overall survival (OS).Results:The objective response rate was 44%. With a mean follow-up time of 31 months (range 2–96 months), the median TTP was 6 months. Median OS was 22 months and reached 34 months in the sub-population of patients (n=12) with the highest plasma DHA incorporation. The most common grade 3 or 4 toxicity was neutropaenia (80%).Conclusion:DHA during chemotherapy was devoid of adverse side effects and can improve the outcome of chemotherapy when highly incorporated. DHA has a potential to specifically chemosensitise tumours.

Conservative treatment feasibility with induction chemotherapy, surgery, and radiotherapy for patients with breast carcinoma larger than 3 cm

Background. The traditional surgical treatment for operable breast carcinoma larger than 3 cm is mastectomy. To avoid mutilating surgery, the authors administered primary chemotherapy to 158 patients with operable nonmetastatic large breast carcinoma with a TNM classification of T2 greater than 3 cm and T3 with a lymph node status of NO‐N1. Conservative treatment was proposed for patients responding to the chemotherapy and whose tumor was reduced to 3 cm or less. The purpose of the study was to evaluate the feasibility and treatment results of this strategy.

n-3 polyunsaturated fatty acids and cancer.

n-3 Polyunsaturated fatty acids are promising molecules in cancer prevention and the potentiation of cancer treatment. Recent studies have highlighted the importance of their interactions with other food components. Their effects on tumor growth depend upon background levels of n-6 polyunsaturated fatty acids and antioxidants, and this could account for previously inconsistent results in experimental carcinogenesis. Recognition of the role of lipoperoxidation in the anti-tumor effects of polyunsaturated fatty acids, which is apparent in a variety of in-vitro or in-vivo systems, has been a major advance in the field. Consequently, n-3 polyunsaturated fatty acids appear to be excellent substrates for lipid peroxidation in situations where an oxidative stress is involved, such as in the action of several cytotoxic agents in the treatment of cancer.

Triacylglycerol structure of human colostrum and mature milk

Because triacylglycerol (TAG) structure influences the metabolic fate of its component fatty acids, we have examined human colostrum and mature milk TAG with particular attention to the location of the very long chain polyunsaturated fatty acid on the glycerol backbone. The analysis was based on the formation of various diacylglycerol species from human milk TAG upon chemical (Grignard degradation) or enzymatic degradation. The structure of the TAG was subsequently deduced from data obtained by gas chromatographic analysis of the fatty acid methyl esters in the diacylglycerol subfractions. The highly specific TAG structure observed was identical in mature milk and colostrum. The three major fatty acids (oleic, palmitic and linoleic acids) each showed a specific preference for a particular position within milk TAG: oleic acid for thesn-1 position, palmitic acid for thesn-2 position and linoleic acid for thesn-3 position. Linoleic and α-linolenic acids exhibited the same pattern of distribution and they were both found primarily in thesn-3 (50%) andsn-1 (30%) positions. Their longer chain analogs, arachidonic and docosahexaenoic acids, were located in thesn-2 andsn-3 positions. These results show that polyunsaturated fatty acids are distributed within the TAG molecule of human milk in a highly specific fashion, and that in the first month of lactation the maturation of the mammary gland does not affect the milk TAG structure.

Voltage-gated Sodium Channel Activity Promotes Cysteine Cathepsin-dependent Invasiveness and Colony Growth of Human Cancer Cells

Voltage-gated sodium channels (NaV) are functionally expressed in highly metastatic cancer cells derived from nonexcitable epithelial tissues (breast, prostate, lung, and cervix). MDA-MB-231 breast cancer cells express functional sodium channel complexes, consisting of NaV1.5 and associated auxiliary β-subunits, that are responsible for a sustained inward sodium current at the membrane potential. Although these channels do not regulate cellular multiplication or migration, their inhibition by the specific blocker tetrodotoxin impairs both the extracellular gelatinolytic activity (monitored with DQ-gelatin) and cell invasiveness leading to the attenuation of colony growth and cell spreading in three-dimensional Matrigel®-composed matrices. MDA-MB-231 cells express functional cysteine cathepsins, which we found play a predominant role (∼65%) in cancer invasiveness. Matrigel® invasion is significantly decreased in the presence of specific inhibitors of cathepsins B and S (CA-074 and Z-FL-COCHO, respectively), and co-application of tetrodotoxin does not further reduce cell invasion. This suggests that cathepsins B and S are involved in invasiveness and that their proteolytic activity partly depends on NaV function. Inhibiting NaV has no consequence for cathepsins at the transcription, translation, and secretion levels. However, NaV activity leads to an intracellular alkalinization and a perimembrane acidification favorable for the extracellular activity of these acidic proteases. We propose that Nav enhance the invasiveness of cancer cells by favoring the pH-dependent activity of cysteine cathepsins. This general mechanism could lead to the identification of new targets allowing the therapeutic prevention of metastases.

Fatty acids and breast cancer: sensitization to treatments and prevention of metastatic re-growth.

Lifestyle and nutritional factors have been recognized to influence breast cancer survival, irrespective of genomic alterations that are the hallmarks of the disease. The biological and molecular mechanisms involved in the effects of dietary polyunsaturated fatty acids and breast cancer response to treatments in clinical and preclinical studies have been reviewed. Among nutrients, rumenic acid, a naturally occurring CLA isomer and n-3 docosahexaenoic acid (DHA) a highly unsaturated fatty acid, have emerged due to their potential to increase cancer treatment efficacy without additional side effects. In this review, we analyze the literature evidence that breast cancer treatment and outcome could be improved through an adjuvant dietary supplementation. Such an original approach would involve two successive phases of breast cancer treatment: an initial sensitization of residual tumor cells to chemotherapy and to radiation therapy with dietary DHA; then a prevention of metastatic re-growth with a prolonged rumenic acid supplementation. Safety is not anticipated to be a critical issue, although it has to be assessed in the long term. Dietary supplements, used in combination to anti-cancer agents, should be provided under medical prescription. Such an original use of fatty acids in breast cancer treatment could provide the lipid field with a new avenue to impact public health.

Neoadjuvant docetaxel for operable breast cancer induces a high pathological response and breast-conservation rate

Docetaxel (Taxotere®), alone or in combination with other anticancer agents, has proven efficacy in the first- and second-line treatment of metastatic breast cancer. This phase II study investigated the efficacy and tolerability of docetaxel as neoadjuvant chemotherapy in women with stage II–III primary operable breast cancer. Patients (n=88) were treated with six cycles of docetaxel at 100 mg m−2 every 21 days, followed by definitive surgery and radiotherapy. After six cycles of docetaxel, the overall clinical response rate was 68.4% (CI 95%: 58.1–78.7%), including 19.0% complete remissions. Breast conservation was achieved in 72.4% of patients. A high pathological complete response (pCR) rate in breast was confirmed in 15 patients (19.8% (CI 95%: 10.8–28.8%)) on Chevalliers classification restricted to breast and in 27 patients (35.5% (CI 95%: 24.7–46.3%)) on Sataloffs classification. After a median follow-up of 30.8 months, 19 recurrences were documented with a median time to first recurrence of 17.3 months. Patients with stage III tumours had more recurrences than patients with stage II tumours (P=0.02). The principal toxicity of docetaxel is myelosuppression and 70.5% of patients developed grade III or IV neutropenia with 13.6% developing neutropenic sepsis. There was no case of severe cardiac toxicity, thrombocytopenia or any other serious adverse events. In conclusion, neoadjuvant docetaxel induces a high pCR and breast-conservation rate. Docetaxel monotherapy is a highly effective regimen that merits formal comparison with currently used combination regimens in a randomised phase III study.

Identification of SK3 channel as a new mediator of breast cancer cell migration

Potassium channels have been involved in epithelial tumorigenesis but the role of small-conductance Ca2+-activated K+ channels is unknown. We report here that small-conductance Ca2+-activated K+ channels are expressed in a highly metastasizing mammary cancer cell line, MDA-MB-435s. Patch-clamp recordings showed typical small-conductance Ca2+-activated K+ channel–mediated currents sensitive to apamin, 4-aminopyridine, and tetraethylammonium. Moreover, the cells displayed a high intracellular calcium concentration, which was decreased after 24 hours of apamin treatment. By regulating membrane potential and intracellular calcium concentration, these channels were involved in MDA-MB-435s cell migration, but not in proliferation. Only SK3 protein expression was observed in these cells in contrast to SK2, which was expressed both in cancer and noncancer cell lines. Whereas small interfering RNA directed against SK3 almost totally abolished MDA-MB-435s cell migration, transient expression of SK3 increased migration of the SK3-deficient cell lines, MCF-7 and 184A1. SK3 channel was solely expressed in tumor breast biopsies and not in nontumor breast tissues. Thus, SK3 protein channel seems to be a new mediator of breast cancer cell migration and represents a potential target for a new class of anticancer agents. [Mol Cancer Ther 2006;5(11):2946–53]

Pivotal role of the lipid raft SK3-Orai1 complex in human cancer cell migration and bone metastases

The SK3 channel, a potassium channel, was recently shown to control cancer cell migration, a critical step in metastasis outgrowth. Here, we report that expression of the SK3 channel was markedly associated with bone metastasis. The SK3 channel was shown to control constitutive Ca(2+) entry and cancer cell migration through an interaction with the Ca(2+) channel Orai1. We found that the SK3 channel triggers an association with the Orai1 channel within lipid rafts. This localization of an SK3-Orai1 complex seemed essential to control cancer cell migration. This suggests that the formation of this complex in lipid rafts is a gain-of-function, because we showed that none of the individual proteins were able to promote the complete phenotype. We identified the alkyl-lipid Ohmline as a disrupting agent for SK3-Orai1 lipid raft localization. Upon Ohmline treatment, the SK3-Orai1 complex moved away from lipid rafts, and SK3-dependent Ca(2+) entry, migration, and bone metastases were subsequently impaired. The colocalization of SK3 and Orai1 in primary human tumors and bone metastases further emphasized the clinical relevance of our observations. Targeting SK3-Orai1 in lipid rafts may inaugurate innovative approaches to inhibit bone metastases.

Effect of an a-Linolenic Acid-Rich Diet on Rat Mammary Tumor Growth Depends on the Dietary Oxidative Status

To investigate whether the oxidative status of an 18:3(n-3) polyunsaturated fatty acid (PUFA)-enriched diet could modulate the growth of chemically induced rat mammary tumors, three independent experiments were performed. Experiments I and II examined the variation of tumor growth by addition of antioxidant (vitamin E) or a prooxidant system (sodium ascorbate/2-methyl-1,4-naphthoquinone) to a 15% linseed oil diet rich in 18:3(n-3). Experiment III addressed the role of PUFA in the tumor growth modulation by vitamin E. For this purpose, we compared the effect of vitamin E in 15% fat diets containing a high level of 18:3(n-3) (linseed oil, high-PUFA diet) or devoid of 18:3(n-3) (hydrogenated palm/sunflower oil, low-PUFA diet). In Experiments I-III, tumor growth increased in the presence of vitamin E compared with control (without vitamin E). Furthermore, it decreased when prooxidant was added. In contrast, no difference was observed when the diet was low in PUFA, suggesting that sensitivity of PUFA to peroxidation may interfere with tumor growth. This observation was supported by growth kinetic parameter analysis, which indicated that tumor growth resulted from variations in cell loss but not from changes in cell proliferation. These data show that, in vivo, PUFA effects on tumor growth are highly dependent on diet oxidative status.