The Role of K-Ras and P53 in Biliary Tract Carcinoma.

OBJECTIVE: To focus mainly on the role of proto-oncogene Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (K-Ras) and tumour-suppressor gene p53 which are among the most commonly mutated genes in biliary tract carcinomas. METHODS: The systematic review comprised research articles published between 2002 and 2019 on PubMed and Google Scholar databases which were searched using the terms 'TP53', 'K-Ras', 'mutation', 'biliary tract carcinoma', 'cholangiocarcinoma', and 'murine model'. Repetitions, duplicates and irrelevant articles were excluded. No data was retrieved from posters, presentations and symposiums, and experiments involving bile aspirations were also excluded. RESULTS: Of the 72 articles reviewed, 11(15.3%) were included. Of them, 3(27.3%) studies, conducted in China, Japan and Taiwan, reported a positive correlation between K-Ras mutation and biliary tract carcinoma. Only 1(9%) study, conducted in China, showed the sole correlation between p53 inactivation and biliary tract carcinoma. Also, 4(36.4%) studies, conducted in China, Japan and Europe, showed a positive association of both K-Ras mutation and p53 inactivation with biliary tract carcinoma. CONCLUSIONS: K-Ras and p53 mutation both contribute to biliary tract carcinoma. K-Ras mutation, however, has a much higher frequency compared to p53 inactivation in such cancers.

Type of TP53 mutation influences oncogenic potential and spectrum of associated K-ras mutations in lung-specific transgenic mice.

TP53 and K-ras mutations are two of the major genetic alterations in human nonsmall cell lung cancers. The association between these two genes during lung tumorigenesis is unknown. We evaluated the potential of two common Type I (273H, contact) and Type II (175H, conformational) TP53 mutations to induce lung tumors in transgenic mice, as well as K-ras status, and other driver mutations in these tumors. Among 516 (138 nontransgenic, 207 SPC-TP53-273H, 171 SPC-TP53-175H) mice analyzed, 91 tumors, all adenocarcinomas, were observed. Type II mutants developed tumors more frequently (as compared to nontransgenics, p = 0.0003; and Type I, p = 0.010), and had an earlier tumor onset compared to Type I (p = 0.012). K-ras mutations occurred in 21 of 50 (42%) of murine lung tumors sequenced. For both the nontransgenic and the SPC-TP53-273H transgenics, tumor K-ras codon 12-13 mutations occurred after 13 months with a peak incidence at 16-18 months. However, for the SPC-TP53-175H transgenics, K-ras codon 12-13 mutations were observed as early as 6 months, with a peak incidence between the ages of 10-12 months. Codons 12-13 transversion mutations were the predominant changes in the SPC-TP53-175H transgenics, whereas codon 61 transition mutations were more common in the SPC-TP53-273H transgenics. The observation of accelerated tumor onset, early appearance and high frequency of K-ras codon 12-13 mutations in the Type II TP53-175H mice suggests an enhanced oncogenic function of conformational TP53 mutations, and gains in early genetic instability for tumors containing these mutations compared to contact mutations.

K-ras mutation promotes ionizing radiation-induced invasion and migration of lung cancer in part via the Cathepsin L/CUX1 pathway.

K-ras mutation is involved in cancer progression including invasion and migration, but the underlying mechanism is not yet clear. Cathepsin L is a lysosomal cysteine protease and has recently been associated with invasion and migration in human cancers when it is overexpressed. Our recent studies have shown that ionizing radiation (IR) enhanced expression of cathepsin L and increased invasion and migration of tumor cells, but the molecular mechanism is still unclear. In the present study, the effects of K-ras mutation and IR induced invasion and migration of lung cancer as well as the underlying mechanisms were investigated both in vitro and in vivo. Firstly, the levels of cathepsin L and epithelial mesenchymal transition (EMT) marker proteins remarkably changed in A549 (K-ras mutant) after irradiation compared with H1299 (K-ras wild), thereby promoting invasion and migration. Additionally, cathepsin L and its downstream transcription factor CUX1/p110 were increased after irradiation in A549 transfected with CUX1/p200, and the proteolytic processing of CUX1 by cathepsin L was remarkably increased after co-transfection of CUX1/p200 and cathepsin L-lentivirus in H1299. In addition, delivery of a mutant K-ras (V12) into HEK 293 cells stimulated EMT after irradiation due to the accumulation of cathepsin L. Moreover, mutated K-ras was associated with IR-induced cathepsin L and EMT in BALB/c nude mice. Finally, the level of cathepsin L expression was higher in samples carrying a K-ras mutation than in wild-type K-ras samples and the mesenchymal markers were upregulated in the samples of mutant K-ras, whereas the epithelial marker E-cadherin was downregulated in non-small cell lung cancers tissues. In conclusion, the findings demonstrated that mutated K-ras promotes cathepsin L expression and plays a pivotal role in EMT of human lung cancer. The regulatory effect of IR-induced cathepsin L on lung cancer invasion and migration was partially attributed to the Cathepsin L /CUX1-mediated EMT signaling pathway. This study will provide cathepsin L as a potential target for tumor therapy.

Inhibition of yes-associated protein suppresses brain metastasis of human lung adenocarcinoma in a murine model.

Yes-associated protein (YAP) is a main mediator of the Hippo pathway and promotes cancer development and progression in human lung cancer. We sought to determine whether inhibition of YAP suppresses metastasis of human lung adenocarcinoma in a murine model. We found that metastatic NSCLC cell lines H2030-BrM3(K-rasG12C mutation) and PC9-BrM3 (EGFRΔexon19 mutation) had a significantly decreased p-YAP(S127)/YAP ratio compared to parental H2030 (K-rasG12C mutation) and PC9 (EGFRΔexon19 mutation) cells (P < .05). H2030-BrM3 cells had significantly increased YAP mRNA and expression of Hippo downstream genes CTGF and CYR61 compared to parental H2030 cells (P < .05). Inhibition of YAP by short hairpin RNA (shRNA) and small interfering RNA (siRNA) significantly decreased mRNA expression in downstream genes CTGF and CYR61 in H2030-BrM3 cells (P < .05). In addition, inhibiting YAP by YAP shRNA significantly decreased migration and invasion abilities of H2030-BrM3 cells (P < .05). We are first to show that mice inoculated with YAP shRNA-transfected H2030-BrM3 cells had significantly decreased metastatic tumour burden and survived longer than control mice (P < .05). Collectively, our results suggest that YAP plays an important role in promoting lung adenocarcinoma brain metastasis and that direct inhibition of YAP by shRNA suppresses H2030-BrM3 cell brain metastasis in a murine model.

The effect of forced expression of mutated K-RAS gene on gastrointestinal cancer cell lines and the IGF-1R targeting therapy.

Mutation in K-RAS (K-RAS-MT) plays important roles in both cancer progression and resistance to anti-epidermal growth factor receptor (EGFR) therapy in gastrointestinal tumors. Insulin-like growth factor-1 receptor (IGF-1R) signaling is required for carcinogenicity and progression of many tumors as well. We have previously shown successful therapy for gastrointestinal cancer cell lines bearing a K-RAS mutation using an anti-IGF-1R monoclonal antibody. In this study, we sought to evaluate effects of forced K-RAS-MT expression on gastrointestinal cancer cell lines representing a possible second resistance mechanism for anti-EGFR therapy and IGF-1R-targeted therapy for these transfectants. We made stable transfectants of K-RAS-MT in two gastrointestinal cancer cell lines, colorectal RKO and pancreatic BxPC-3. We assessed the effect of forced expression of K-RAS-MT on proliferation, apoptosis, migration, and invasion in gastrointestinal cancer cells. Then we assessed anti-tumor effects of dominant negative IGF-1R (IGF-1R/dn) and an IGF-1R inhibitor, picropodophyllin, on the K-RAS-MT transfectants. Overexpression of K-RAS-MT in gastrointestinal cancer cell lines led to more aggressive phenotypes, with increased proliferation, decreased apoptosis, and increased motility and invasion. IGF-1R blockade suppressed cell growth, colony formation, migration, and invasion, and up-regulated chemotherapy-induced apoptosis of gastrointestinal cancer cells, even when K-RAS-MT was over-expressed. IGF-1R blockade inhibited the Akt pathway more than the extracellular signal-regulated kinase (ERK) pathway in the K-RAS-MT transfectants. IGF-1R/dn, moreover, inhibited the growth of murine xenografts expressing K-RAS-MT. Thus, K-RAS-MT might be important for progressive phonotype observed in gastrointestinal cancers. IGF-1R decoy is a candidate molecular therapeutic approach for gastrointestinal cancers even if K-RAS is mutated. © 2016 Wiley Periodicals, Inc.

Differential Effects of Variations at Codon 106 on Sprouty2 Functions in Lung Cancer-Derived Cells.

Sprouty2 is a modulator of receptor tyrosine kinase-mediated signalling with an important role during lung carcinogenesis. Here, we characterize a Sprouty2 variant harbouring a substitution of proline 106 with serine. Serine substitution fails to influence expression, but accumulation of slower migrating phosphatase-sensitive forms indicates that its presence facilitates phosphorylation. In normal lung cells the serine variant is slightly more potent in inhibiting proliferation and migration. Additionally non-malignant cells expressing the major Sprouty2 variant attach more effective to fibronectin, while the serine variant only weakly stimulates cell adhesion. Mechanistically, the serine variant interferes less effectively with mitogen-activated protein kinase induction in response to serum. Concerning the positive Sprouty2 effect on epidermal growth factor receptor activation the serine variant is more potent. In all lung cancer-derived cell lines proliferation is more effectively inhibited if the Sprouty2 protein harbours the serine. In contrast, an increased interference of the serine Sprouty2 variant is only observed in cells with unaltered K-Ras. In cells harbouring a K-Ras mutation the serine conversion weakens the reduction of migration velocity indicating that dependent on the status of K-Ras the serine influences Sprouty2 functions differently. Accordingly, cell adhesion in cells with unaffected K-Ras is only stimulated by a Sprouty2 protein harbouring proline, while a serine conversion improves the attachment of the cells with constitutive active Ras. In summary our studies demonstrate that substitution of proline by serine at position 106 has biological significance and that the observed effects of this conversion depend on the activation status of endogenous K-Ras. J. Cell. Biochem. 117: 1822-1832, 2016. © 2016 Wiley Periodicals, Inc.

A case of pulmonary adenocarcinoma harboring osteoclast-like giant cells: Its evaluation by immunohistochemical and genetic analyses.

Tumors harboring osteoclast-like giant cells (OGCs) at extraosseous site are extremely rare. These rare tumors have been detected most frequently in the pancreas and few pulmonary tumors harboring OGCs have been previously reported. In addition, the genetic profiles of these tumors have remained virtually unknown. Therefore, we report a case of pulmonary adenocarcinoma harboring OGCs in which k-ras mutation and immunohistochemical study of proteins associated with OGCs were examined. The case was a 70-year-old man, who demonstrated a pulmonary mass associated with unusual radiological features. Histopathologically, three different cell types, mucinous adenocarcinoma cell, OGC and mononuclear cell were detected. OGCs were immunohistochemically negative for epithelial markers and positive for histiocytic markers but mononuclear cells were immunopositive for epithelial markers. In addition, both mononuclear and adenocarcinoma cells had the same k-ras mutation profiles and mononuclear cells were immunohistochemically positive for macrophage colony-stimulating factor (M-CSF), one of the factors associated with OGC differentiation. Therefore, mononuclear cells were considered to be derived from neoplastic epithelium and OGCs could represent non-neoplastic cells. In addition, M-CSF locally produced could promote the differentiation of OGCs.

Discrepancies between the K-ras mutational status of primary colorectal cancers and corresponding liver metastases are found in codon 13.

K-ras mutation status has remained elusive in the metastatic liver tumors of colorectal cancer (CRC) in contrast to the primary CRC tumors. In this study, K-ras mutational status of the primary and corresponding liver metastatic tumors was investigated in the 43 CRC patients. Codons 12 and 13 of K-ras were directly sequenced, and a K-ras mutation was evident in 17 cases (39.5%). In 6 cases, the K-ras mutation was evident only in the liver metastasis, but not in the primary CRC, where the mutation was found in codon 13. This discrepancy between primary and metastatic lesions with regard to codon 13 of the K-ras gene may explain the clinical discrepancy of EGFR antibody therapy. In conclusion, the current data may lead to the development of personalized medicine for recurrent CRC, although further validation study is still required.

Discordance of Mutation Statuses of Epidermal Growth Factor Receptor and K-ras between Primary Adenocarcinoma of Lung and Brain Metastasis.

Mutations on epidermal growth factor receptor (EGFR) of adenocarcinomas of lung have been found to be associated with increased sensitivity to EGFR tyrosine kinase inhibitors and K-ras mutations may correlate with primary resistance. We aimed to explore the discordant mutation statuses of EGFR and K-ras between primary tumors and matched brain metastases in adenocarcinomas of lung. We used a sensitive Scorpion ARMS method to analyze EGFR mutation, and Sanger sequencing followed by allele-specific real-time polymerase chain reaction to analyze K-ras mutation. Forty-nine paired tissues with both primary adenocarcinoma of lung and matched brain metastasis were collected. Thirteen patients (26.5%) were discordant for the status of EGFR between primary and metastatic sites. K-ras gene could be checked in paired specimens from 33 patients, thirteen patients (39.6%) were discordant for the status of K-ras. In primary lung adenocarcinoma, there were 14 patients of mutant EGFR had mutant K-ras synchronously. This study revealed that the status of EGFR mutation in lung adenocarcinomas is relatively consistent between primary and metastatic sites compared to K-ras mutation. However, there are still a few cases of adenocarcinoma of lung showing discordance for the status of EGFR mutation. Repeated analysis of EGFR mutation is highly recommended if tissue from metastatic or recurrent site is available for the evaluation of target therapy.

Multifocal synchronous mucinous adenocarcinomas arising in congenital pulmonary airway malformation: a case report with molecular study.

AIMS: Congenital pulmonary airway malformation (CPAM) is a rare developmental anomaly of the lung. Here, we report a case of mucinous adenocarcinoma arising in CPAM. A 23-month-old boy underwent a thoracoscopic lobectomy of the left upper lobe of the lung based on a presumptive diagnosis of asymptomatic CPAM, found in antenatal sonogram. METHODS AND RESULTS: Histologically, the lesion was consistent with CPAM, Stocker type I. In addition, multiple foci ranging from mucinous epithelial hyperplasia to mucinous adenocarcinoma were detected. All lesions shared the same immunoprofile with the expression of cytokeratin (CK) 20, MUC5AC, and human epidermal growth factor receptor2 (HER2), but were negative for CK7, transcription factor 1 (TTF-1), MUC1, CDX2, BRAF (VE1) and anaplastic lymphoma kinase (ALK). K-RAS point mutation (G12V) was also detected in all micro-dissected mucinous lesions but EGFR mutation was not found. All lesions were consistent with mucinous adenocarcinoma. The patient's clinical course has been uneventful during the 12-months follow-up period. CONCLUSIONS: This interesting case demonstrated that multiple foci in CPAM can synchronously transform into malignancies.

Colorectal liver metastases patients prognostic assessment: prospects and limits of radiomics and radiogenomics.

In this narrative review, we reported un up-to-date on the role of radiomics to assess prognostic features, which can impact on the liver metastases patient treatment choice. In the liver metastases patients, the possibility to assess mutational status (RAS or MSI), the tumor growth pattern and the histological subtype (NOS or mucinous) allows a better treatment selection to avoid unnecessary therapies. However, today, the detection of these features require an invasive approach. Recently, radiomics analysis application has improved rapidly, with a consequent growing interest in the oncological field. Radiomics analysis allows the textural characteristics assessment, which are correlated to biological data. This approach is captivating since it should allow to extract biological data from the radiological images, without invasive approach, so that to reduce costs and time, avoiding any risk for the patients. Several studies showed the ability of Radiomics to identify mutational status, tumor growth pattern and histological type in colorectal liver metastases. Although, radiomics analysis in a non-invasive and repeatable way, however features as the poor standardization and generalization of clinical studies results limit the translation of this analysis into clinical practice. Clear limits are data-quality control, reproducibility, repeatability, generalizability of results, and issues related to model overfitting.

Simultaneous p53 and KRAS mutation in a high-grade serous carcinoma with deceptive appearance of a low-grade carcinoma. A case report.

Low-grade and high-grade serous carcinomas have unique clinical, morphological, underlying molecular alterations, and vastly different biologic behavior (Prat et al., 2018, Vang et al., 2009). The differentiation into high and low-grade serous carcinoma is important for clinical management and prognosis and is easily recognized by practicing pathologists. High-grade serous carcinoma is characterized by marked nuclear atypia and pleomorphism, frequent, often atypical mitosis with papillary or three-dimensional clusters, p53 mutation, and block-like p16 staining. In contrast, low-grade serous carcinomas have a different morphologic appearance with micropapillary formation, small nests of tumor cells having low to intermediate grade nuclei, and absence of significant mitosis. Low-grade serous carcinoma is often associated with micropapillary variant of ovarian serous borderline tumor. The low-grade serous carcinoma shows wild type p53 expression, patchy p16 staining, and often K-RAS, N-RAS, and/or B-RAF mutation. Here we report a case of mullerian high grade serous with a deceptive morphology resembling low-grade serous carcinoma with micropapillary features and moderate nuclear atypia. However, the tumor is simultaneously p53 and K-RAS mutated. This case illustrates three critical issues; a) potential to be mistaken as a low-grade serous carcinoma because of morphologic appearance and relative uniform cytologic feature. b). raise the question of true progression of low-grade to high-grade serous carcinoma, a rare phenomenon as described in the literature, and c). whether the biologic behavior and/or response to therapy would differ from the classic forms.

Rapid recurrence of a ruptured mucinous borderline ovarian tumor harboring K-RAS mutation followed by progression into anaplastic carcinoma with TP53 mutation.

We describe the case of a young patient with a borderline mucinous ovarian tumor that progressed into ipsilateral ovarian anaplastic carcinoma in only 3 months with metastasis to the contralateral ovary and extensive spread in the pelvic and abdominal regions. The mucinous tumor harbored micro-foci of intraepithelial carcinoma, but no mural nodules, microinvasion, or invasive adenocarcinoma were detected. Notably, a rupture on the ovarian mass and low-grade pseudomyxoma peritonei were present. Next-generation sequencing identified an identical KRAS mutation in the mucinous tumor and anaplastic carcinoma, while the latter had KRAS gene amplification and CDKN2A, MPL and TP53 mutations. These findings indicate the anaplastic carcinoma might have arisen via recurrence, malignant transformation and dedifferentiation of the former low-grade mucinous tumor. We consider that the mass rupture and pseudomyxoma peritonei were high-risk factors for recurrence, while genetic mutations were key drivers of progression. Accordingly, such cases may benefit from active surgical treatment and early chemotherapy.

Low Cost, Easily-Assembled Centrifugal Buoyancy-Based Emulsification and Digital PCR.

Microfluidic-based droplet generation approaches require the design of microfluidic chips and a precise lithography process, which require skilled technicians and a long manufacturing time. Here we developed a centrifugal buoyancy-based emulsification (CBbE) method for producing droplets with high efficiency and minimal fabrication time. Our approach is to fabricate a droplet generation module that can be easily assembled using syringe needles and PCR tubes. With this module and a common centrifuge, high-throughput droplet generation with controllable droplet size could be realized in a few minutes. Experiments showed that the droplet diameter depended mainly on centrifugal speed, and droplets with controllable diameter from 206 to 158 µm could be generated under a centrifugal acceleration range from 14 to 171.9 g. Excellent droplet uniformity was achieved (CV < 3%) when centrifugal acceleration was greater than 108 g. We performed digital PCR tests through the CBbE approach and demonstrated that this cost-effective method not only eliminates the usage of complex microfluidic devices and control systems but also greatly suppresses the loss of materials and cross-contamination. CBbE-enabled droplet generation combines both easiness and robustness, and breaks the technical challenges by using conventional lab equipment and supplies.

Ovarian mucinous tumors with mural nodules: immunohistochemical and molecular analysis of 3 cases.

BACKGROUND: Primary ovarian mucinous tumors with mural nodules are very rare. The histogenesis of the mural nodules remains unclear. METHODS: We investigated the clincopathological and molecular features in 3 cases with mural nodules. RESULTS: Patient 1 was diagnosed as mucinous carcinoma with mural nodules of anaplastic carcinoma that was composed of CK+ and CK7+ spindled cells and polygonal cells with marked pleomorphism. Aberrant p53 staining was found in the mural nodules rather than in the mucinous components. A concordant KRAS mutation (c.35G > A p.G12A) was identified in both mucinous tumors and mural nodules. She died of disease at 44 months. The mural nodule in patient 2 was interpreted as a sarcoma, no other specified. The uniform short spindle cells were separated by abundant myxoid matrix. They were CD10 + , CCND1-, SMA-, and negative for break-apart BCOR, PHF1, and JAZF1 FISH assay. The adenocarcinomatous component harbored LOH at D18S51 and FGA loci while the sarcomatous component had LOH at D19S433. She had lung metastasis at 18 months and was alive without evidence of disease for 40 months. Patient 3 harbored multiple mural nodules that were composed of vimentin+, focal CK+, atypical spindle cells. A diagnosis of sarcoma-like mural nodules was rendered. She was alive with no evidence of disease for 13 months. No hotspot mutant AKT1, KRAS, HRAS, and PI3KCA alleles were found in patients 2 and 3. CONCLUSIONS: Mural nodules with anaplastic carcinoma or with true sarcomas may represent the dedifferentiation form of mucinous tumors or collision tumors, respectively. The worrisome histology in sarcoma-like mural nodules necessitates meticulous treatment for these patients.

An albumin­binding domain and targeting peptide­based recombinant protein and its enediyne­integrated analogue exhibit directional delivery and potent inhibitory activity on pancreatic cancer with K­ras mutation.

Efficient enrichment and transmembrane transport of cytotoxic reagents are considered to be effective strategies to increase the efficiency and selectivity of antitumor drugs targeting solid tumors. In the present study, a recombinant protein ABD­LDP­Ec consisting of the albumin­binding domain (ABD), the apoprotein (LDP) of lidamycin (LDM) and an EGFR­targeting oligopeptide (Ec) was prepared by DNA recombination and bacterial fermentation, and was integrated with the enediyne chromophore (AE) of lidamycin to generate its enediyne­integrated analogue ABD­LDP­Ec­AE. ABD­LDP­Ec exhibited high binding capacity to both albumin and EGFR­positive pancreatic cancer cells, and was internalized into the cytoplasm through receptor­mediated endocytosis and albumin­driven macropinocytosis of K­ras mutant cells. In animal experiments, ABD­LDP­Ec demonstrated notable selective distribution in pancreatic carcinoma xenografts by passive targeting of albumin captured in the blood and was retained in the tumor for 48 h. ABD­LDP­Ec and ABD­LDP­Ec­AE exhibited inhibitory activity in cell proliferation and AsPC­1 xenograft growth, and ABD­LDP­Ec­AE increased the tumor growth inhibition rate by 20% compared with natural LDM. The results indicated that the introduction of ABD­based multi­functional drug delivery may be an effective approach to improve the efficacy of antitumor drugs, especially for K­ras mutant cancers.

Impact of smoking on frequency and spectrum of K-RAS and EGFR mutations in treatment naive Indonesian lung cancer patients.

Background: Indonesia has the highest cigarette consumption in the world. We explored the clinical impact of smoking on the prevalence of EGFR and K-RAS mutations and survival in this prospective study. Methods: 143 treatment naive lung cancer patients were recruited from Persahabatan Hospital, a national tertiary hospital. DNA from cytological specimens had been extracted and genotyped for both EGFR and K-RAS mutations using a combination of PCR high resolution melting, restriction fragment length polymorphism (RFLP) and direct DNA sequencing. Results: EGFR mutation frequency in never smokers (NS) and ever smokers (ES) were 75% and 56% (p = 0.0401), respectively. In this cohort, the overall K-RAS mutation rate was 7%. Neither gender nor smoking history were associated with K-RAS mutation significantly. However, K-RAS transversion mutations were more common in male ES than transition mutations. Smoking history did not affect EGFR and K-RAS mutation frequencies in women. Concurrent EGFR/K-RAS mutation rate was 2.8% (4 of 143 patients). Four out of 91 EGFR mutation positive patients (4.4%) had simultaneous K-RAS mutation. Conclusions: In region where cigarette consumption is prevalent, smoking history affected frequencies of EGFR and K-RAS mutations, mainly in males.

Recent Advances in Developing K-Ras Plasma Membrane Localization Inhibitors.

The Ras proteins play an important role in cell growth, differentiation, proliferation and survival by regulating diverse signaling pathways. Oncogenic mutant K-Ras is the most frequently mutated class of Ras superfamily that is highly prevalent in many human cancers. Despite intensive efforts to combat various K-Ras-mutant-driven cancers, no effective K-Ras-specific inhibitors have yet been approved for clinical use to date. Since K-Ras proteins must be associated to the plasma membrane for their function, targeting K-Ras plasma membrane localization represents a logical and potentially tractable therapeutic approach. Here, we summarize the recent advances in the development of K-Ras plasma membrane localization inhibitors including natural product-based inhibitors achieved from high throughput screening, fragment-based drug design, virtual screening, and drug repurposing as well as hit-to-lead optimizations.

Erlotinib for Patients with EGFR Wild-Type Metastatic NSCLC: a Retrospective Biomarkers Analysis.

Erlotinib is approved for the treatment of patients with EGFR mutation positive, metastatic NSCLC. It is also approved as second/third line therapy for EGFR mutation negative patients, but in this setting the benefit of erlotinib is modest and there is no validated biomarker for selecting EGFR wild-type patients who may benefit the most from the treatment. We retrospectively assessed EGFR and K-RAS mutational status, and EGFR, c-MET and IGF1-R expression in tumor samples of 72 patients with metastatic NSCLC treated with erlotinib after at least one prior line of chemotherapy, from 2008 to 2012. We analyzed the association between biomarkers and outcome (RR, PFS, and OS). EGFR mutated patients achieved a better RR (56% vs 8%, p = .002), PFS (10 vs 3 months, HR 0.53, p = 0.48) and OS (20 vs 6 months, HR 0.55, p = .07), compared to EGFR wild-type patients. Among 63 EGFR wild-type patients, those with EGFR high-expression had a better outcome in terms of RR (40% vs 2%, p = .002), PFS (7.5 vs 2 months, HR 0.45, p = .007) and OS (30 vs 5 months, HR 0.34, p < .001) compared to patients with EGFR intermediate or low/negative-expression. IGF1-R expression, c-MET expression and K-RAS mutational status did not significantly affect the outcome; however, no patients with K-RAS mutation or c-MET high-expression achieved an objective response. In patients with metastatic, chemo-refractory EGFR wild-type NSCLC, EGFR high-expression may represent a positive predictor of activity for erlotinib, whereas K-RAS mutation and c-MET high-expression may predict lack of activity. These findings deserve further prospective evaluation.

K-ras Mutations as the Earliest Driving Force in a Subset of Colorectal Carcinomas.

K-ras oncogene is a key factor in colorectal cancer. Based on published and our data we propose that K-ras could be the oncogene responsible for the inactivation of the tumor-suppressor gene APC, currently considered as the initial step in colorectal tumorigenesis. K-ras fulfills the criteria of the oncogene-induced DNA damage model, as it can provoke well-established causes for inactivating tumor-suppressors, i.e. DNA double-strand breaks (causing allele deletion) and ROS production (responsible for point mutation). The model we propose is a variation of the currently existing model and hypothesizes that, in a subgroup of colorectal carcinomas, K-ras mutation may precede APC inactivation, representing the earliest driving force and, probably, an early biomarker of colorectal carcinogenesis. This observation is clinically useful, since it may modify the preventive colorectal cancer strategy, restricting numerically patients undergoing colonoscopies to those bearing K-ras mutation in their colorectum, either in benign polyps or the normal accompanying mucosa.