PIK3CA Mutations In Colorectal Cancer Research Articles

Abstract 4125: Exploring the efficacy of alpelisib and combined PI3Kα-S6K inhibition in LIN28B-mediated colorectal cancer metastasis

Abstract Introduction: Colorectal cancer (CRC) is the third most diagnosed cancer worldwide. LIN28B, an RNA-binding protein that regulates mRNA translation, has garnered significant interest in recent cancer research. Our lab has established that LIN28B is an oncogene and promotes CRC metastasis. However, the exact mechanisms through which LIN28B exerts these effects remain elusive. The phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway is altered in 50-70% of CRCs and is characterized by PIK3CA gene mutations in 20-30% of CRC cases. PIK3CA encodes the catalytic subunit p110α of the PI3Kα enzyme, which is critical for PI3K/AKT signaling. Activation of this pathway is associated with worse CRC prognosis. Among the components of this signaling cascade, the ribosomal protein S6 kinase (S6K) is a crucial downstream effector, playing a pivotal role in protein synthesis and cell growth. Despite the frequent occurrence of PIK3CA mutations in CRC, targeted therapies for PIK3CA-mutant CRC are lacking. Alpelisib, a PI3Kα-specific inhibitor approved by the FDA for a subset of PIK3CA-mutant breast cancers, remains largely unassessed in CRC. We hypothesize that LIN28B-mediated CRC metastasis is facilitated by the activation of the PI3K/AKT pathway, representing a potential target for Alpelisib or other related inhibitors. Results: Our data indicate that LIN28B expression in CRC cells promotes liver metastasis in mouse models of metastatic CRC (mCRC). Furthermore, LIN28B expression activates the PI3K/AKT pathway, as measured by an AKT phosphorylation array. Treatment of CRC cells with SC79, a pan-AKT activator, enhanced cell migration and invasiveness. Similarly, VillinCre;R26Pik3ca transgenic mice, expressing a constantly active mutant form of PI3Kα in the intestinal epithelium, demonstrated crypt hyperplasia and an amplified propensity for tumorigenesis, mirroring the effects of LIN28B expression in CRC. Importantly, Alpelisib effectively hinders LIN28B-driven CRC progression in cell lines, transgenic mice-derived organoids, and mCRC mouse models, as well as the growth rate of CRC patient-derived organoids (PDOs). The effects observed with Alpelisib treatment were replicated with inhibition of S6K using either LY25284702 or PF4708671. Moreover, a combination of low-dose Alpelisib with low-dose LY25284702 or PF4708671 synergistically restricted the growth of PDOs. Conclusion: Our data provide compelling evidence that the PI3K/AKT pathway regulates LIN28B-mediated CRC metastasis, and its inhibition by Alpelisib is feasible. This underscores the potential for precision medicine in CRC, offering targeted therapies to PIK3CA-mutant CRC patients who lack specific treatment options. Furthermore, our study highlights the clinical advantages of combined inhibition strategies for improved anti-metastatic outcomes, a field in dire need of interventions in mCRC. Citation Format: Alice E. Shin, Kensuke Sugiura, Secunda W. Kariuki, David A. Cohen, Christopher J. Lengner, Peter A. Sims, Joel T. Gabre, Anil K. Rustgi. Exploring the efficacy of alpelisib and combined PI3Kα-S6K inhibition in LIN28B-mediated colorectal cancer metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4125.

Prevalence of PIK3CA Mutation Based on Tumour Locations Among Colorectal Cancer Patients in Bali

Colorectal tumour location is important in determining therapeutic strategies because the location of the tumour will affect the histological and molecular characteristics of the cancer. Phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) is a gene known to be associated with colorectal cancer location. The prevalence of PIK3CA mutations in colorectal cancer (CRC) ranges from 10-20%. Although the prevalence is small, this gene has a potential as a predictive and prognostic biomarker in the management of CRC. 80% of PIK3CA mutations occur in exon 9 (codon 542 and 545) and exon 20 (codon 1047). This study aimed to determine the prevalence of PIK3CA gene mutations based on tumour location among colorectal cancer patients in Bali, especially in Prof. dr. I G.N.G. Ngoerah Hospital, Denpasar, Bali. DNA was isolated from formalin-fixed-paraffin embedded (FFPE) blocks of colorectal cancer samples which were stored in the Department of Pathology of Prof. dr. I G.N.G. Ngoerah Hospital. Mutation was detected using polymerase chain reaction (PCR) and direct sequencing. Data on age, gender, and tumour location were recorded from patient medical records. Our findings on 31 colorectal cancer samples showed 26 samples (96.3%) were found with heterozygous mutation in exon 9 with AC genotype, but no mutation was found on exon 20. Based on tumor location, among 26 samples with mutation, 16 samples (61.5%) were left colorectal cancer and 10 samples (38.5%) were right colorectal cancer. Further studies are needed to identify the association of this mutation with colorectal cancer location and the other clinicopathological aspects of CRC. Keywords: Colorectal cancer, PIK3CA gene mutation, PIK3CA exon 9, PIK3CA exon 20, colorectal cancer location, left-sided colorectal cancer, right-sided colorectal cancer

Solid Organ Transplantation Is Associated with an Increased Rate of Mismatch Repair Deficiency and PIK3CA Mutations in Colorectal Cancer.

Solid organ transplants are associated with a modestly increased risk of colorectal cancers (CRC). However, the molecular profile of these cancers has not been described. We hypothesized that transplant-related immunosuppression may promote development of more immunogenic tumors as suggested by a high tumor mutation burden or mismatch repair deficiency. We performed an electronic medical record search for patients seen in the Johns Hopkins University Health System (JHHS) between 2017 and 2022 who developed CRC following solid organ transplantation. A comparator cohort of patients treated for CRC at JHHS with molecular profiling data was also identified. In this case, 29 patients were identified that developed post-transplant CRC (renal transplant, n = 18; liver transplant, n = 8; kidney-liver transplantation, n = 3). Compared to the JHHS general population CRC cohort, patients who developed post-transplant CRC had a higher rate of mismatch repair deficiency (41% versus 12%, p-value = 0.0038), and elevated tumor mutation burden (median of 22 mut/Mb versus 3.5 mut/Mb, p-value = 0.033) (range 3.52-53.65). Post-transplant tumors were enriched for PIK3CA mutations (43% versus 24%, p-value = 0.042). Post-Transplant CRCs are associated with clinical and molecular features of immune sensitivity, supporting a potential role for impaired immune surveillance in shaping the landscape of CRCs. These results may help inform the management of patients with post-transplant CRC.

PIK3CA mutation affects the proliferation of colorectal cancer cells through the PI3K-MEK/PDK1-GPT2 pathway.

The phosphatidylinositol‑3‑kinase catalytic subunitα (PIK3CA) gene is mutated in numerous human cancers. This mutation promotes the proliferation of tumor cells; however, the underlying mechanism is still not clear. In the present study, it was revealed that the PIK3CA mutation in colorectal cancer(CRC) HCT116(MUT) rendered the cells more dependent on glutamine by regulating the glutamic‑pyruvate transaminase2 (GPT2). The dependence of glutamine increased the proliferation of cells in a normal environment and resistance to a suboptimal environment. Further study revealed that the mutated PIK3CA could regulate GPT2 expression not only through signal transduction molecule3‑phosphoinositide‑dependent kinase (PDK1) but also through mitogen‑activated protein kinase (MEK) molecules. In HCT116 cells, MEK inhibitor treatment could reduce the expression of GPT2 signaling molecules, thereby inhibiting the proliferation of CRC cells. A new signal transduction pathway, the PI3K/MEK/GPT2 pathway was identified. Based on these findings, MEK and PDK1 inhibitors were combined to inhibit the aforementioned pathway. It was revealed that the combined application of MEK and PDK1 inhibitors could promisingly inhibit the proliferation of MUT compared with the application of PI3K inhibitors, PDK1 inhibitors, or MEK inhibitors alone. Invivo, MEK inhibitors alone and combined inhibitors had stronger tumor‑suppressing effects. There was no significant difference between the PDK1‑inhibitor group and normal group invivo. Thus, these results indicated that mutated PI3K affected GPT2 mediated by the MEK/PDK1 dual pathway, and that the PI3K/MEK/GPT2 pathway was more important invivo. Inhibiting MEK and PDK1 concurrently could effectively inhibit the proliferation of CRC cells. Targeting the MEK and PDK1 signaling pathway may provide a novel strategy for the treatment of PIK3CA‑mutated CRC.

Correlation of PIK3CA mutation with programmed death ligand-1 (PD-L1) expression and their clinicopathological significance in colorectal cancer.

BackgroundThe prognostic significance of PIK3CA mutations in colorectal cancer (CRC) remains controversial. Recently, an association between programmed death ligand-1 (PD-L1) and PIK3CA mutations has been reported. The study presented here was conducted to investigate the effect of PIK3CA mutations on the prognosis of CRC patients and the association between PIK3CA mutations and PD-L1.MethodsPIK3CA mutations were analyzed by targeted next-generation sequencing using formalin-fixed paraffin-embedded specimens from 224 primary CRC patients. PD-L1 expression was evaluated by immunohistochemical staining.ResultsPIK3CA mutations and PD-L1 expression were detected in 21.4% and 10.3% of CRC patients, respectively. PIK3CA mutations were significantly correlated with right-side colon cancer (P=0.011) and were correlated inversely with lymph node metastasis (P=0.026), distant metastasis (P=0.047), and high TNM stage (P=0.036). In univariate analysis, PIK3CA mutations were correlated with longer relapse-free survival in CRC patients. PD-L1 expression was correlated significantly with PIK3CA mutations (P<0.001).ConclusionsPIK3CA mutations were associated with favorable prognostic factors, longer relapse-free survival, and expression of PD-L1. Further investigation is needed to identify whether PIK3CA mutations are a good prognostic factor. Additionally, further studies are needed to understand the mechanisms behind the correlation between PIK3CA mutations and PD-L1 expression.

The Landscape of PIK3CA Mutations in Colorectal Cancer

BackgroundColorectal cancer is one of the most common malignancies in both men and women. Despite progress in the treatment of the disease, metastatic colorectal cancer remains lethal with a median survival slightly surpassing 2 years and commonly for some cases a more aggressive course. New therapies are urgently needed based on a better understanding of the molecular pathogenesis of the disease. MethodsThe focus of this investigation is the PIK3CA gene, encoding the alpha catalytic subunit of the enzyme phosphatidylinositol-3 kinase (PI3K). Publicly available data from 3 extensive published series of colorectal carcinomas were analyzed to define the molecular landscape of colorectal adenocarcinomas with and without mutations of PIK3CA. An analysis for discovery of associations with alterations in other critical genes and pathways involved in colorectal cancer was performed. The total mutation burden (TMB) and copy number alteration burden of colorectal cancers with and without mutations of PIK3CA, as well as prognostic implications of alterations of the gene for survival, were examined. ResultsMutations in PIK3CA are observed in 20% to 25% of colorectal cancers. PIK3CA represents one of the most frequently mutated oncogenes in these cancers. Mutations in PIK3CA are associated with higher rates of mutations in other genes of important cancer-associated pathways such as the tyrosine kinase receptors/K-Ras/BRAF/MAPK and the Wnt/β-catenin pathway. In addition, PIK3CA mutated colorectal cancers display a higher TMB than nonmutated cancers. ConclusionFrequent mutations of PIK3CA gene in colorectal carcinomas may represent an opportunity for targeted therapy combination development inhibiting both the PI3K kinase itself and associated pathway defects. Increased TMB may additionally confer immunotherapy sensitivity, which could be augmented by other targeted therapies.

Prevalence and characteristics of PIK3CA mutation in mismatch repair-deficient colorectal cancer.

Background: Chromosomal instability (CIN) and microsatellite instability (MSI) account for the major causes of colorectal cancer (CRC). As an important component of the CIN pathway, PIK3CA mutation is a negative prognostic factor in CRC. However, the relationship between PIK3CA mutation and mismatch repair (MMR) status has not been well clarified.Methods: MMR status was determined by immunohistochemical assay. KRAS, NRAS, BRAF, PIK3CA and TP53 mutations were comparatively analyzed in 424 MMR-proficient (pMMR) and 104 MMR-deficient (dMMR) CRC tumors using next-generation sequencing (NGS).Results: PIK3CA mutation was more commonly mutated in dMMR tumors. PIK3CA mutation less commonly coexisted with KRAS/NRAS/BRAF and TP53 mutations, but more likely coexisted with HER2 and PTCH1 mutations in dMMR tumors compared with pMMR tumors. In tumors with concurrent RAS/BRAF and PIK3CA mutations, PIK3CA and RAS/BRAF mutant allele frequencies (MAFs) were highly concordant in dMMR tumors, whereas PIK3CA MAFs were significantly lower than the corresponding RAS/BRAF MAFs in pMMR tumors, implying that PIK3CA mutation may occur in the early stage of dMMR CRC.Conclusions: The molecular pathogenesis is different between dMMR and pMMR tumors with PIK3CA mutation in CRC. PIK3CA mutation may act as a clonally dominant truncal mutation in dMMR CRC. Thus, combination of PIK3CA mutation and MMR status might determine a specific group of CRC to select treatment or elevate prognosis.

Abstract 2733: Novel mouse model carrying APC and PIK3CA mutations in colorectal cancer

Abstract Colorectal cancer (CRC) is the third leading cause of cancer-related deaths in the United States, despite substantial development in its early diagnosis and treatment. The animal models of CRC have been immensely useful for understanding CRC pathogenesis, investigating the effects of genetic modifications on CRC, and for the development of new chemopreventive/chemotherapeutic drugs. Most (&amp;gt;80%) CRC carry mutations in the APC gene and many (15-20%) carry mutations in the PIK3CA gene, encoding the p110 catalytic subunit of the PI3K kinase. We sought to better understand the interaction between APC and PIK3CA mutations in the mammalian intestine. To examine the effect of mutations in APC and PIK3CA on tumorigenesis, Min mice were crossed with the FC13K1 (FC13K1ApcMin/+). This cross resulted in a murine model with the loss of one allele of Apc throughout the intestine and the expression of a dominant active PI3K (3K1) in the distal small intestine and colon due to the expression of Cre under the control of the rat fatty acid binding protein-1 promoter (FC1). There was increased tumor multiplicity, size and a more aggressive and poorly differentiated phenotype as a consequence of synergy between APC and PIK3CA mutations. Tumors form as adenomas, but quickly progress to invasive adenocarcinomas that eventually metastasize to regional lymph nodes. Using this mouse model, we have recently shown that fisetin, a dietary flavonoid could be used as a preventive agent and an adjuvant with 5-fluorouracil (FU) for the treatment of PIK3CA-mutant CRC. Tumor incidence was markedly lower in fisetin-treated FC13K1ApcMin/+ mice in distal small intestine and colon, as compared to control animals, indicating that fisetin is a strong preventive agent. In addition, the combination of fisetin and 5-FU also reduced the total number of intestinal tumors. We extended our work by demonstrating that the effect of drugs on tumorigenesis was impacted by the mutation profile of the tumor and intratumoral heterogeneity. We developed the mouse model in which intestinal tumors were composed entirely of PIK3CA wild-type cells, entirely of PIK3CA-mutant cells, or a mixture of both. We demonstrated that low dose aspirin blocked the development of heterogeneous tumors composed of PIK3CA wild-type and PIK3CA-mutant cells but not the development of homogenous tumors composed entirely of PIK3CA wild-type cells. Thus, this new model of CRC recapitulates the effect of aspirin that was observed in humans. Sustained exposure to low dose aspirin reduced the recurrence the PIK3CA-mutant CRC cancers in humans. This aggressive murine model is an exciting model of human CRC that has the potential to be instrumental in the development of targeted chemoprevention and therapeutics. Citation Format: Naghma Khan, Farah Jajeh, Emily L. Eberhardt, Devon D. Miller, Dawn M. Albrecht, Rachel Van Doorn, Melissa D. Hruby, Morgan E. Maresh, Linda Clipson, Hasan Mukhtar, Richard B. Halberg. Novel mouse model carrying APC and PIK3CA mutations in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2733.

A Small Cog in a Big Wheel: PIK3CA Mutations in Colorectal Cancer

A Small Cog in a Big Wheel: PIK3CA Mutations in Colorectal Cancer

Aspirin Use, Tumor PIK3CA Mutation, and Colorectal-Cancer Survival

BackgroundRegular use of aspirin after a diagnosis of colon cancer has been associated with a superior clinical outcome. Experimental evidence suggests that inhibition of prostaglandin-endoperoxide synthase 2 (PTGS2) (also known as cyclooxygenase-2) by aspirin down-regulates phosphatidylinositol 3-kinase (PI3K) signaling activity. We hypothesized that the effect of aspirin on survival and prognosis in patients with cancers characterized by mutated PIK3CA (the phosphatidylinositol-4,5-bisphosphonate 3-kinase, catalytic subunit alpha polypeptide gene) might differ from the effect among those with wild-type PIK3CA cancers.MethodsWe obtained data on 964 patients with rectal or colon cancer from the Nurses' Health Study and the Health Professionals Follow-up Study, including data on aspirin use after diagnosis and the presence or absence of PIK3CA mutation. We used a Cox proportional-hazards model to compute the multivariate hazard ratio for death. We examined tumor markers, including PTGS2, phosphorylated AKT, KRAS, BRAF, microsatellite instability, CpG island methylator phenotype, and methylation of long interspersed nucleotide element 1.ResultsAmong patients with mutated-PIK3CA colorectal cancers, regular use of aspirin after diagnosis was associated with superior colorectal cancer–specific survival (multivariate hazard ratio for cancer-related death, 0.18; 95% confidence interval [CI], 0.06 to 0.61; P<0.001 by the log-rank test) and overall survival (multivariate hazard ratio for death from any cause, 0.54; 95% CI, 0.31 to 0.94; P=0.01 by the log-rank test). In contrast, among patients with wild-type PIK3CA, regular use of aspirin after diagnosis was not associated with colorectal cancer–specific survival (multivariate hazard ratio, 0.96; 95% CI, 0.69 to 1.32; P=0.76 by the log-rank test; P=0.009 for interaction between aspirin and PIK3CA variables) or overall survival (multivariate hazard ratio, 0.94; 95% CI, 0.75 to 1.17; P=0.96 by the log-rank test; P=0.07 for interaction).ConclusionsRegular use of aspirin after diagnosis was associated with longer survival among patients with mutated-PIK3CA colorectal cancer, but not among patients with wild-type PIK3CA cancer. The findings from this molecular pathological epidemiology study suggest that the PIK3CA mutation in colorectal cancer may serve as a predictive molecular biomarker for adjuvant aspirin therapy. (Funded by The National Institutes of Health and others.)

Characteristics and prevalence of KRAS, BRAF, and PIK3CA mutations in colorectal cancer by high-resolution melting analysis in Taiwanese population

BackgroundThe identification of KRAS, BRAF, and PIK3CA mutations before the administration of anti-epidermal growth factor receptor therapy of colorectal cancer has become important. The aim of the present study was to investigate the occurrence of KRAS, BRAF, and PIK3CA mutations in the Taiwanese population with colorectal cancer. This study was undertaken to identify BRAF and PIK3CA mutations in patients with colorectal cancer by high-resolution melting (HRM) analysis. HRM analysis is a new gene scan tool that quickly performs the PCR and identifies sequence alterations without requiring post-PCR treatment. MethodsIn the present study, DNAs were extracted from 182 cases of formalin-fixed, paraffin-embedded (FFPE) colorectal cancer samples for clinical KRAS mutational analysis by direct sequencing. All the samples were also tested for mutations within BRAF V600E and PIK3CA (exons 9 and 20) by HRM analysis. ResultsThe results were confirmed by direct sequencing. The frequency of BRAF and PIK3CA mutations is 1.1%, and 7.1%, respectively. Intriguingly, we found that nine patients (4.9%) with the KRAS mutation were coexistent with the PIK3CA mutation. Four patients (2.2%) without the KRAS mutation were existent with the PIK3CA mutation. Two patients (1.1%) without the KRAS mutation were existent with the BRAF mutation. ConclusionsIn the current study, we suppose that HRM analysis is rapid, feasible, and powerful diagnostic tool for the detection of BRAF and PIK3CA mutations in a clinical setting. Additionally, our results indicated the prevalence of KRAS, BRAF, and PIK3CA mutational status in the Taiwanese population.

4E-BP1 Is a Key Effector of the Oncogenic Activation of the AKT and ERK Signaling Pathways that Integrates Their Function in Tumors

PIK3CA and PTEN alterations are common in human cancer, but only a fraction of such tumors are dependent upon AKT signaling. AKT independence is associated with redundant activation of cap-dependent translation mediated by convergent regulation of the translational repressor 4E-BP1 by the AKT and ERK pathways. This provides mechanistic bases for the limited activity of AKT and MEK inhibitors in tumors with comutation of both pathways and the profound synergy observed with combined inhibition. Whereas such tumors are sensitive to a dominant active 4E-BP1 mutant, knockdown of 4E-BP1 expression reduces their dependence on AKT/ERK signaling for translation or survival. Thus, 4E-BP1 plays a prominent role in mediating the effects of these pathways in tumors in which they are activated by mutation.

PIK3CA Mutation in Colorectal Cancer: Relationship with Genetic and Epigenetic Alterations

Somatic PIK3CA mutations are often present in colorectal cancer. Mutant PIK3CA activates AKT signaling, which up-regulates fatty acid synthase (FASN). Microsatellite instability (MSI) and CpG island methylator phenotype (CIMP) are important molecular classifiers in colorectal cancer. However, the relationship between PIK3CA mutation, MSI and CIMP remains uncertain. Using Pyrosequencing technology, we detected PIK3CA mutations in 91 (15%) of 590 population-based colorectal cancers. To determine CIMP status, we quantified DNA methylation in eight CIMP-specific promoters [CACNA1G, CDKN2A (p16), CRABP1, IGF2, MLH1, NEUROG1, RUNX3, and SOCS1] by real-time polymerase chain reaction (MethyLight). PIK3CA mutation was significantly associated with mucinous tumors [P = .0002; odds ratio (OR) = 2.44], KRAS mutation (P < .0001; OR = 2.68), CIMP-high (P = .03; OR = 2.08), phospho–ribosomal protein S6 expression (P = .002; OR = 2.19), and FASN expression (P = .02; OR = 1.85) and inversely with p53 expression (P = .01; OR = 0.54) and β-catenin (CTNNB1) alteration (P = .004; OR = 0.43). In addition, PIK3CA G-to-A mutations were associated with MGMT loss (P = .001; OR = 3.24) but not with MGMT promoter methylation. In conclusion, PIK3CA mutation is significantly associated with other key molecular events in colorectal cancer, and MGMT loss likely contributes to the development of PIK3CA G>A mutation. In addition, Pyrosequencing is useful in detecting PIK3CA mutation in archival paraffin tumor tissue. PIK3CA mutational data further emphasize heterogeneity of colorectal cancer at the molecular level.