Developing drugs that target KRAS, the most frequently mutated oncogene in cancer, has not been successful despite much concerted efforts dedicated towards it in the last thirty years. Considering the key role this driver oncogene plays, the pharmacological drugging of KRAS remains a key challenge for cancer research. In this review, we highlight the emerging experimental strategies for blocking KRAS function and signaling and its direct targeting. We also report on the results in this field of research produced by our group.

Identifying appropriate preclinical cancer models remains a major challenge in increasing the efficiency of drug development. A potential strategy to improve patient outcomes could be selecting the ‘right’ treatment in preclinical studies performed in patient-derived xenografts (PDXs) obtained by direct implants of surgically resected tumours in mice. These models maintain morphological similarities and recapitulate molecular profiling of the original tumours, thus representing a useful tool in evaluating anticancer drug response. In this review, we will present the state-of-art use of PDXs as a reliable strategy to predict clinical findings. The main advantages and limitations will also be discussed.

Telomeres are specialized nucleoprotein structures responsible for protecting chromosome ends in order to prevent the loss of genomic information. Telomere maintenance is required for achieving immortality by neoplastic cells. While most cancer cells rely on telomerase re-activation for linear chromosome maintenance and sustained proliferation, a significant population of cancers (10–15%) employs telomerase-independent strategies, collectively referred to as Alternative Lengthening of Telomeres (ALT). ALT mechanisms involve different types of homology-directed telomere recombination and synthesis. These processes are facilitated by loss of the ATRX or DAXX chromatin-remodeling factors and by abnormalities of the telomere nucleoprotein architecture. Although the functional consequences of telomerase and ALT up-regulation are similar in that they both prevent overall telomere shortening in tumors, these telomere maintenance mechanisms (TMMs) differ in several aspects which may account for their differential prognostic significance and response to therapy in various tumor types. Therefore, reliable methods for detecting telomerase activity and ALT are likely to become an important pre-requisite for the use of treatments targeting one or other of these mechanisms. However, the question whether ALT presence can confer sensitivity to rationally designed anti-cancer therapies is still open. Here we review the latest discoveries in terms of mechanisms of ALT activation and maintenance in human tumors, methods for ALT identification in cell lines and human tissues and biomarkers validation. Then, original results on sensitivity to rational based pre-clinical and clinical anti-tumor drugs in ALT vs hTERT positive cells will be presented.

Naphthalened iimide (NDI) dyads exhibiting ad ifferent substitution pattern and linker length have been synthesiseda nd evaluateda sG -quadruplex (G4) ligands,b yi nvestigating their cytotoxicity in selected cell lines. The dyads with the long C 7 linker exhibit extremelyl ow IC 50 values, below 10 nm,o nd ifferent cancerc ell lines.C ontrary,t he dyads with the shorter C 4 linker were much less effective, with IC valuesi ncreasing up to 1 mm.A mong the three dyads with the longest linker, small differences in the IC 50 valuese merge, suggesting that the linker length plays a more important role than the substitution pattern. We have further shown that the dyads are able to induce cellular DNA damage response, whichi sn ot limited to the telomeric regions and is likely the origin of their cytotoxicity.B oth absorptiont itration and dynamic light scattering of the most cytotoxic dyads in the presence of hTel22 highlight their abilityt oi nduce effective G4 aggregation,a cting as non-covalentc ross-linking agents.[a] Dr.Scheme1.NDI dyads 5-16 synthesised andevaluated as G4 ligands in comparisontot he reference monomericNDI units 1-4.Scheme2.Synthesis of the water-soluble NDI dyads. a) Amine (3.0 equiv), CH 3 CN, 75 8C, 5h.b )Na 2 S 2 O 4 (2 equiv) in aqueous CH 3 CN (1:1), RT,2h. c) NDI 17 (0.95equiv), DMF,m icrowave-assistedprotocol, sealed reactionv essels (M.W., 150 8C, 200 psi, 200 W, 20 min). d) Neat N 1 ,N 1 -dimethylpropane-1,3-diamine, microwave-assistedprotocol, sealed reactionv essels (M.W., 150 8C, 200 psi, 200 W, 3min). Absorption, CD and fluorescencespectraUV/Vis absorption spectra were recorded on as tandard Perkin-Elmer l650 spectrophotometer.C Ds pectra were recorded on a Jasco polarimeter J-715 accumulating four spectra with as can rate of 100 nm min À1 .F luorescence spectra were measured by using 1nms teps and 0.5-1 sd well time. Slits were kept as narrow as possible to 4-8 nm in excitation and 4-8 nm in emission. Where necessary,acut-off filter was used. Right angle detection was used. All the measurements were carried out at 295 Ki nq uartz cuvettes with ap ath length of 1cm. All fluorescence spectra have been obtained for air-equilibrated solutions absorbing less than 0.1 at all wavelengths to avoid inner filter effects and re-absorption of the emission. Furthermore, they have been corrected for wavelengthdependent response of the monochromator/PMT couple.

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