The increased cap-independent translation of anti-apoptotic proteins is involved in the development of drug resistance in lung cancer but signalling events regulating this are poorly understood. Fibroblast growth factor 2 (FGF-2) signalling-induced S6 kinase 2 (S6K2) activation is necessary, but the downstream mediator(s) coupling this kinase to the translational response is unknown. Here, we show that S6K2 binds and phosphorylates hnRNPA1 on novel Ser4/6 sites, increasing its association with BCL-XL and XIAP mRNAs to promote their nuclear export. In the cytoplasm, phosphoS4/6-hnRNPA1 dissociates from these mRNAs de-repressing their IRES-mediated translation. This correlates with the phosphorylation-dependent association of hnRNPA1 with 14-3-3 leading to hnRNPA1 sumoylation on K183 and its re-import into the nucleus. A non-phosphorylatible, S4/6A mutant prevented these processes, hindering the pro-survival activity of FGF-2/S6K2 signalling. Interestingly, immunohistochemical staining of lung and breast cancer tissue samples demonstrated that increased S6K2 expression correlates with decreased cytoplasmic hnRNPA1 and increased BCL-XL expression. In short, phosphorylation on novel N-term sites of hnRNPA1 promotes translation of anti-apoptotic proteins and is indispensable for the pro-survival effects of FGF-2.

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Accurate classification of nonsmall cell lung cancers is of paramount clinical relevance, as novel chemotherapeutic agents show different efficacy in adenocarcinomas (ADCs) compared with squamous cell carcinomas (SQCCs). Cyto and histomorphology may sometimes be insufficient for this distinction and immunohistochemistry may improve diagnostic accuracy. The measurement of miR-205 may be another tool for the distinction between ADC and SQCC. The aim of our study was to compare morphologic and immunohistochemical classification with the relative quantification of miR-205 and miR-21 insurgically resected and well-characterized lung tumors (25 ADCs, 24 SQCCs, 1 adenosquamous). The miR-21 relative levels were similar in SQCC and ADC, whereas the miR-205 relative levels were lower in ADC (P<0.0001). The miR-205 sample score value, determined according to Lebanony et al, was higher in ADC (range, 2.8 to 9.08) compared with SQCC (range, -4.17 to 2.445) (P<0.0001). Accordingly, 22 tumors were classified as ADC and 28 tumors as SQCC, although 8 cases (2 SQCCs and 6 ADCs) were in the range of "near cutoff values." Four cases classified as SQCC (according to the sample score method) corresponded to cases classified as ADC on the basis of morphoimmunohistochemical evaluation. In conclusion, the relative quantification of miR-205 and miR-21 seems to be a promising diagnostic tool. However, the molecular approach is still not completely satisfactory as it may misclassify a non-negligible percentage of cases. Therefore, it cannot be used as a substitute of accurate morphologic and immunophenotypical characterization of tumors, but could be used as an adjunctive diagnostic criterion in selected cases.

The purpose of this study is to evaluate whether activating mutations of the p110α catalytic subunit of class A phosphoinositide 3-kinases (PI3KCA) or complete loss of phosphatase and tensin homolog (PTEN) is associated with response to anti-human epidermal growth factor receptor 2 (Her2) treatment in breast cancer (BC). We analysed PI3KCA hot-spot mutations and PTEN immunohistochemical expression in 129 Her2-positive infiltrating BC treated with trastuzumab, including 26 cases treated with neoadjuvant therapy, 48 metastatic infiltrating breast cancer (IBC; MBC) and 55 early-stage IBC, with complete clinical information (mean follow-up 37, 66 and 32 months, respectively). PI3KCA hot-spot mutations were observed in 25 cases (19 %): 12 (9 %) in exon 9 and 13 (10 %) in exon 20. No correlations were observed between mutations and pathological and biological parameters. In patients treated with neoadjuvant therapy and in MBC, we did not observe any relationship with response to trastuzumab-based therapy. PTEN loss was observed in 24 out of 86 informative cases (28 %), 3 (13 %) of which were also mutated for PI3KCA. PI3K pathway activation, defined as PI3KCA mutation and/or PTEN loss, was not associated with response to treatment or clinical outcome in MBC. PI3KCA mutation and/or PTEN loss should not exclude patients from potentially beneficial anti-Her2 therapy.

PI3K/AKT/mTOR pathway alterations are frequent in patients with infiltrating breast cancer (IBC). Their clinical and pathological relevance has been insufficiently documented. We evaluated PI3KCA for mutations and the expression of PTEN, AKT, mTOR and p70S6K by immunohistochemistry in 246 IBC patients treated with hormone therapy (median follow-up, 97 months). A PI3KCA mutation was observed in 50 out of 229 informative cases (21.8 %), PTEN loss in 107 out of 210 (51 %), moderate/high level of expression of AKT in 133 out of 188 (71 %), moderate/high level of expression of mTOR in 173 out of 218 (79 %) and moderate/high level of expression of p70S6K in 111 out of 192 cases (58 %). PI3KCA mutation was associated with the absence of Her2/neu amplification/overexpression and a low level of MIB1/Ki-67 labelling. The expression of p70S6K was associated with a high level of mTOR immunoreactivity, and high PTEN expression was associated with high AKT expression level. Univariate analysis showed that PI3KCA mutation status was not associated with clinical outcome in the series as a whole or in the node-negative subgroup. However, in the node-positive subgroup, exon 9 PI3KCA mutation was associated with unfavourable overall survival (OS), although its impact on the final model in multivariate analysis seemed to be limited. Of the other markers, only high p70S6K expression was associated with a significantly prolonged OS. PI3KCA mutation status is of limited prognostic relevance in oestrogen receptor-positive breast cancer patients treated with hormone therapy.